Home Physical Sciences Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids
Article Open Access

Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids

  • Xiaoling Hu , Xingang Jia EMAIL logo , Kehe Su and Xuefan Gu
Published/Copyright: June 9, 2020
Download Article (PDF)
Open Chemistry
From the journal Open Chemistry Volume 18 Issue 1

Abstract

Electronic structural properties of the three different imidazolium-based ionic liquids, namely, 1-butyl-3-methyl imidazolium bromide (C4mimBr), 1-(4-hydroxybutyl)-3-methylimidazolium bromide (C4OHmimBr), and 1-(4-aminobutyl)-3-methylimidazolium bromide (C4NH2mimBr), were investigated with density functional theory at the B3LYP/6-311++G(d,p) level. The conformations of the mentioned cations were fully studied first using CONFLEX 8.A program. The quantum theory of atoms in molecules was used to investigate the nature of intramolecular interactions. The counterpoise-corrected ion pairs binding energies were obtained at the same level of theory. Natural bond orbital analyses show that the largest intra-molecular interaction comes from the orbital overlap between n(N1) and π* (N4–C5) in the mentioned compounds. The energy levels of frontier molecular orbitals (FMOs) are displayed. The global quantum chemical descriptors are also calculated based on the energy values of FMOs.

Keywords: ionic liquids; conformations; frontier molecular orbitals; intramolecular interactions

1 Introduction

Ionic liquids (ILs) are usually defined as salts with a melting point below 100°C, commonly having a large organic cation and a small inorganic or organic anion [1,2,3]. ILs have unique physicochemical properties including high thermal stability, negligible vapor pressure, non-flammability, and good solving ability to inorganic and organic substances [4]. Therefore, ILs are considered as suitable alternatives in numerous applications, especially as green solvents in chemical processes such as synthesis, catalysis, biocatalysis, and separation [5,6,7,8,9,10]. However, due to the possible combinations of cation and anion, it was estimated that the number of ILs could be up to 1018 from the statistical point of view [11]. It is a good way to design the novel task-specific ILs by using a quantum calculation. More interests have been focused on the relationship between the structure and properties [12,13,14]. Currently, the most widely used imidazolium-based ILs have been studied both experimentally and theoretically [15,16,17]. The introduction of the amino/hydroxyl group into the alkyl side chain of cation can lead to some interesting modifications to the behavior of the conventional imidazolium-based ILs. For example, Sun et al. [18] found that hydroxyl-functional ILs showed high catalytic activity in the coupling reaction of carbon dioxide and epoxide. Yue et al. [19] used dual amino-functionalized ILs as a catalyst for the synthesis of carbonate. It is of practical importance to develop a molecule-level understanding of the properties of ILs to design or utilize them for future applications. Furthermore, the results of ab initio calculations could be used to develop suitable force fields and models for molecular dynamics simulations that would allow accurate theoretical predictions of ILs [20,21]. In the present work, the molecular structure and electronic properties of three different imidazolium-based ILs, namely, 1-butyl-3-methyl imidazolium bromide (C4mimBr), 1-(4-hydroxybutyl)-3-methylimidazolium bromide (C4OHmimBr), and 1-(4-aminobutyl)-3-methylimidazolium bromide (C4NH2mimBr), were studied with density functional theory (Figure 1).

Figure 1 Scheme of three different imidazolium-based ILs.
Figure 1

Scheme of three different imidazolium-based ILs.

2 Computational section

To predict the possible conformations of the cations, the CONFLEX conformational search method [22,23,24] using strategies designed to exhaustively search the conformational space of the target molecule as implemented in the CONFLEX 8.A [25] program was used. The energy of the predicted conformations was estimated using the MMFF94s force field [26]. To get more accurate geometry and energy order of the predicted conformations, further ab initio computations were performed by Gaussian 16 software package [27]. The predicted conformations were geometry optimized at the B3LYP [28,29] level using the 6-311++G(d,p) basis set. The level of B3LYP/6-311++G(d,p) used to predict the geometry and electronic properties of ILs had been successful during the past few years [30,31,32]. The MP2 energy was calculated at the B3LYP optimized geometry using the same basis set. Vibration analyses were proceeded to confirm the optimized structure corresponding to the minimum on the potential energy surface by verifying the absence of imaginary frequency and to obtain the zero-point vibrational energy. The basis sets superposition error (BSSE) is calculated with the counterpoise (CP) correction method [33]. Natural population analyses [34] were also carried out at the same level of theory. The analysis of the noncovalent interactions involved in the molecules was performed with Bader’s quantum theory of atoms in molecules (QTAIM [35]) as implemented in Multiwfn 3.6 [36]. The topological graphs were drew using VMD 1.9.3 [37].

  1. Ethical approval: The conducted research is not related to either human or animal use.

3 Results and discussion

3.1 Conformation and geometry analysis of cations

As a constituent of IL, cation in ILs is usually organic asymmetric ion. Due to the high flexibility of the alkyl side chains, the conformers of cations are complexed. To obtain the most stable conformer of the cation, the conformational search was first carried out within 10 kcal/mol energy cutoff using CONFLEX 8.A software. After the first conformation searching, 9, 44, and 73 conformations were predicted for C4mim+, C4OHmim+, and C4NH2mim+, respectively. The ls4 file, one of the output files after searching, contains a list of conformers in order of free energy. If there is F indicated in the INIT row, it means that some conformational isomers derived from this structure still have not been obtained. Higher energy cutoff value was again set to 20 kcal/mol for C4OHmim+ and C4NH2mim+. Their ls4 files were included in the Supporting information. Finally, there are 9, 46, and 74 conformations for C4mim+, C4OHmim+, and C4NH2mim+, respectively. Among the generated conformations, 6, 2, and 9 conformations were selected, the sum of their distribution was above 90%, for C4mim+, C4OHmim+, and C4NH2mim+, respectively. The ab initio calculations were used to get more accurate geometry and energy order of the selected conformations at the B3LYP and MP2 levels in the gas phase. The relative energies based on the molecular mechanics and ab initio calculations are listed in Table 1.

Table 1

Relative energies of the selected conformations of cations a,b,c,d

ItemsNo.MMFF94s (kcal/mol)B3LYP (kcal/mol)MP2 (kcal/mol)Dihedral angles (°)
D (3,4,7,8)D (4,7,8,9)D (7,8,9,10)
C4mim+10.000.260.00−70.9−60.4−177.3
20.050.660.4495.7−64.6−176.8
30.360.000.9074.6179.9179.9
40.641.100.23−70.8−64.3−65.5
50.701.470.6795.5−64.9−65.1
61.110.811.37−75.9−178.7−66.3
C4OHmim+10.000.000.00−89.01−62.48−63.01
20.000.000.00−89.02−62.48−62.99
C4NH2mim+10.000.000.00−85.69−68.02−57.78
21.180.871.29−150.53−105.8563.33
31.190.871.29−150.54−105.8563.37
41.230.000.00−85.73−68.05−57.76
51.310.962.3571.09177.14−76.07
61.391.811.29−85.45−174.3753.67
71.471.572.5999.27113.99−77.88
81.481.572.5999.25113.99−77.87
91.541.192.57−82.88177.82−75.55
  1. a

    No, B3LYP, and MP2 stand for conformational number, B3LYP/6-311++G(d, p), and MP2/6-311++G(d, p).

  2. b

    Energy of conformation 1 of C4mim+ at the MMFF94s, B3LYP, and MP2 is 26.19 kcal/mol, −423.062830 a.u., and −421.773144 a.u., respectively; energy of conformation 1 of C4OHmim+ at the MMFF94s, B3LYP, and MP2 is 18.10 kcal/mol, −498.304494 a.u, and −496.851973 a.u, respectively; energy of conformation 1 of C4NHmim+ at the MMFF94s, B3LYP, and MP2 is 15.82 kcal/mol, −478.415974 a.u, and −476.984135 a.u., respectively.

  3. c

    Qualitative description of the dihedral angles is based on the B3LYP/6-311++G(d, p) geometry.

  4. d

    Dihedral angles are for optimized conformers at the B3LYP/6-311++G(d,p) level, and atom numbering is shown in Figure 2.

Note that in Table 1, the dihedral angles are also displayed and provided some information on the molecular structure. The number of conformations of C4NH2mim+ was reduced to 6 after geometry optimization because the geometry of No. 2 and 3, No. 7 and 8, and No. 1 and 4 is the same. Although the energy order at the B3LYP and MP2 levels is little different from that at the MMFF94s level, the biggest energy gap between the conformations of the mentioned cations is less than 3 kcal/mol. Taking C4NH2mim as an example at the MP2 level, the conformation 7/8, the fifth-lowest energy, is higher in energy than the conformation 1 by 2.59 kcal/mol.

3.2 Geometry and QTAIM analysis of ion pairs

The previous work showed that the anion could locate on different places around the cation [38]. When the Br anion is located near the hydrogen atom attached to the C5 atom in the planar imidazolium ring, the most stable structure on the potential energy surface is confirmed. Figure 2 displays the molecular topological graphs based on their gas-phase optimized geometries at the B3LYP/6-311++G(d, p) level.

Figure 2 Topological graphs of (a) C4mimBr, (b) C4NH2mimBr, and (c) C4OHmimBr. H atoms are in white, C atoms are in cyan, N atoms are in blue, O atoms are in red, and Br atoms are in ochre.
Figure 2

Topological graphs of (a) C4mimBr, (b) C4NH2mimBr, and (c) C4OHmimBr. H atoms are in white, C atoms are in cyan, N atoms are in blue, O atoms are in red, and Br atoms are in ochre.

We further employed a QTAIM study on the ion pairs to show X⋯H interactions which were identified as bond paths (shown in Figure 2 as an orange line) between atoms (atom critical points) and bond critical points (BCPs, shown in Figure 2 as an orange point). Topological parameters, such as the electron density and the Laplacian of electron density at the BCP, have been computed and listed in Table 2.

Table 2

Topological parameters of the QTAIM in C4mimBr, C4NH2mimBr, and C4OHmimBr

Ion pairsIntramolecular interactionsρ(r)∇2ρ(r)G(r)V(r)−G(r)/V(r)Eint (kcal/mol)
C4mimBrH13⋯Br260.0340.0630.019−0.0220.8646.903
H15⋯Br260.0110.0280.006−0.0051.2001.569
C4NH2mimBrH14⋯Br280.0260.0580.014−0.0141.0044.520
H25⋯Br280.0130.0330.007−0.0061.2321.767
H27⋯Br280.0150.0390.009−0.0071.1822.267
H20⋯Br280.0030.0080.002−0.0011.3100.405
H15⋯N110.0170.0490.011−0.0091.1672.910
C4OHmimBrH14⋯Br280.0150.0880.019–0.0151.2214.768
H24⋯Br280.0100.0390.008−0.0025.1610.501
H25⋯Br280.0150.0910.020−0.0161.1955.123
H14⋯O110.0050.0210.005−0.0041.1911.205
H15⋯O110.0150.0640.014−0.0121.1403.919

G(r) is the kinetic energy density at the BCP (always positive), and V(r) is the potential energy density at the BCP (always negative). Generally, the value of ρ(r) greater than 0.20 a.u. is for covalent bonding interactions and less than 0.10 a.u. is for closed-shell interactions [39]. The parameters (ρ and ∇2ρ) can also be used to distinguish between covalent and ionic bonding, hydrogen bonding, and van der Waals interactions. A negative value of ∇2ρ stands for a concentration of electron density. For BCP, positive ∇2ρ indicates noncovalent bonding. Eint is determined by 0.5 V(r) and used to estimate weak interatomic interaction energies, particularly for hydrogen bonds [40]. It is obvious from Table 2 that all ∇2ρ values are positive and the ρ(r) values are all less than 0.10 a.u. The interaction energies listed in Table 2 can be classified as weak (0–4 kcal/mol) or medium (4–14 kcal/mol) according to Jeffrey’s classification of hydrogen bonds [41]. It is noted that more hydrogen bonds are formed when amino or hydroxyl functional groups are introduced. Compared with C4mim+, the introduction of the amino/hydroxyl functional group has a great effect on the spatial distribution of the alkyl side chain.

3.3 Ion-pair binding energy

The binding energy of the ion pairs is defined as the difference between the total energy of the ion pair and the sum of the energies of the isolated ions:

ΔE(AB)=EAB−[EA+EB]

where EA or EB is the energy of isolated cation or anion and EAB is the energy of the ion pair. Each of the energies has been corrected with the zero-point energy. The binding energy is further corrected with the BSSE with the CP correction method. The CP corrected ion-pair binding energies are calculated using the following equation:

ΔECP(AB)=ΔE(AB)+δABBSSE.

The results are listed in Table 3.

Table 3

Ion-pair binding energies, BSSEs, and CP-corrected binding energies (kcal/mol), calculated at the B3LYP/6-311+G(d,p) level

EntryIon-pair binding energyBSSECP-corrected binding energy
C4mimBr−85.630.17−85.46
C4OHmimBr−87.500.23−87.27
C4NH2mimBr−85.940.20−85.74

The values of binding energy in Table 3 show that the introduction of the amino/hydroxyl group has a little effect on the increase of the binding energy compared with C4mimBr.

3.4 NBO analysis

Natural bond orbital (NBO) analysis provides a convenient method for interpreting intra- and intermolecular bonding and interactions among bonds in the molecule. For a better understanding of the orbital interactions, the stabilization energy E(2) is calculated according to the second-order perturbation theory [42]. For each donor NBO(i) and acceptor NBO(j), the stabilization energy associated with delocalization i, j orbitals is estimated as

E(2)=qi(Fi,j)2Ei−Ej

where qi is the donor orbital occupancy, Ei and Ej are diagonal elements (orbital energies), and Fi,j is the off-diagonal NBO Fock matrix element. Some major donor–acceptor NBO interactions and the second-order perturbation stabilization energies are listed in Table 4. In NBO analysis, the larger the E(2) value, the more intensive the interaction between electron donors and electron acceptors and the greater the extent of conjugation of the whole system.

Table 4

The major interactions and the stabilization energies at the B3LYP/6-311++G(d, p) level

Donor NBO(i)Bond typeOccupancyAcceptor NBO(j)Bond typeOccupancyE(2) kcal/molE(j)–E(i) a.uF(i,j) a.u
C4mimBr
LP (4)Brn1.8578BD*(2) N4–C5π*0.554218.610.140.050
LP (1)N1n1.5264BD*(2) C2–C3π*0.257131.510.280.089
LP (1)N1n1.5264BD*(2) N4–C5π*0.554275.500.220.118
BD(2)N4–C5π1.8913BD*(2)C2–C3π*0.257117.400.370.074
BD*(2)N4–C5π*0.5542BD*(2)C2–C3π*0.257119.120.060.047
C4OHmimBr
LP(4)Brn1.8598BD*(2) N4–C5π*0.554018.170.140.050
LP(1)N1n1.5246BD*(2) C2–C3π*0.257331.620.280.089
LP(1)N1n1.5246BD*(2) N4–C5π*0.554075.910.220.118
LP(2)O11n1.9657BD*(1)C10–H24σ*0.02244.460.740.051
LP(2)O11n1.9657BD*(1)C10–H25σ*0.02606.590.720.062
BD(2)N4–C5π1.8914BD*(2)C2–C3π*0.257317.380.370.074
BD*(2)N4–C5π*0.5540BD*(2)C2–C3π*0.257319.110.060.047
C4NH2mimBr
LP(4)Brn1.8595BD*(2) N4–C5π*0.553418.330.140.050
LP(1)N1n1.5258BD*(2)C2–C3π*0.257231.520.280.089
LP(1)N1n1.5258BD*(2) N4–C5π*0.553475.690.220.118
LP(1)N11n1.9650BD*(1)C10–H25σ*0.02646.520.740.062
BD(2)N4–C5π1.8913BD*(2)C2–C3π*0.257217.400.370.074
BD*(2)N4–C5π*0.5534BD*(2)C2–C3π*0.257219.160.060.047

Due to the structural similarity of the three imidazolium-based compounds, a similar trend of interaction is observed. Taking C4NH2mimBr as an example, the most strongest intra-molecular hyper conjugative interaction is formed by the orbital overlap between n(N1) and π*(N4–C5). The interaction of n(N1) and π*(N4–C5) results in the increases of electron density (0.5534e) in π*(N4–C5) that weakens the respective bonds leading to stabilization of about 75.69 kcal/mol. Another intra-molecular hyper conjugative interaction between n(N1) and π*(C2–C3) ca. uses the increases of electron density (0.2572e) in π*(C2–C3) and leads to stabilization of about 31.52 kcal/mol. The interaction of n(4)Br and π*(N4–C5) contributes to the stabilization with the value of 18.33 kcal/mol. These major interactions are also observed for C4mimBr and C4OHmimBr. The NBO analysis also shows the natural hybrids on atoms in the molecule. The hybridization of n(N1) has considerable p-character (99.88%) with a low occupation number (1.5258e). The hybridization of n(4)Br has a high p-character (96.60%) with a high occupation number (1.8595e). The π(N4–C5) bond is formed from sp4.16 on nitrogen with a mixture of 0.17% s, 99.78% p, and 0.04% d atomic orbitals. The information about the hybridization on the atom and the bonding configuration shows the strong delocalization and hyperconjugative interactions in the molecule. As for C4OHmimBr, the stabilization energy caused by the interaction of n(2)O and σ*(C10–H25) is 6.59 kcal/mol. As for C4NH2mimBr; it is similar that the interaction between n(1)N11 and σ*(C10–H25) resulted in the decreasing energy with a value of 6.52 kal/mol.

To understand the distribution of electron density and the electron transfer between cation and anion, the natural population atom charges of ion pairs were also computed. Most of the negative charge is located on the Br atom. They are −0.856e, −0.850e, and −0.866e for C4mimBr, C4OHmimBr, and C4NH2mimBr, respectively. The electron transfer from the Br anion to cation is 0.144e, 0.150e, and 0.134e for C4mimBr, C4OHmimBr, and C4NH2mimBr, respectively.

3.5 Frontier molecular orbitals

The frontier molecular orbitals (FMOs) are mainly at the “frontier” of electron occupation, especially the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO). The 3D plots of FMOs are drawn at 0.05 a.u. by using the program Multiwfn [36] and VMD1.9.3 [37]. FMOs of ion pairs are displayed in Figure 3.

Figure 3 HOMO (lower) and LUMO (upper) orbital plots at the B3LYP/6-311++G (d, p) level: (a) C4mimBr, (b) C4OHmimBr, and (c) C4NH2mimBr
Figure 3

HOMO (lower) and LUMO (upper) orbital plots at the B3LYP/6-311++G (d, p) level: (a) C4mimBr, (b) C4OHmimBr, and (c) C4NH2mimBr

The blue color reflects a positive phase, whereas the red color refers to a negative phase. It is observed that the HOMO in C4mimBr, C4OHmimBr, and C4NH2mimBr is the non-bonding orbital (lone pair of Br anion). The energy values of HOMO for them are −4.96, −5.42, and −5.16 eV, respectively. LUMO is anti-bonding in nature π*(N4–C5) in the ring. The energy values of LUMO are −3.65, −3.07, and −3.88 eV, respectively. The energy levels of HOMO and LUMO give information on electronic properties. The energy gap between LUMO and HOMO is also an important parameter for chemical reactivity and stability.

According to Koopmans’ theorem, the ionization potential (IP) and electron affinity (EA) can be estimated from the HOMO and LUMO energy values. The global reactivity descriptors such as hardness, softness, electrophilicity, and chemical potential, electronegativity are related to the energy values of HOMO and LUMO. They were also calculated using HOMO and LUMO energy values and listed in Table 5. The values of IP and EA in parentheses were also calculated according to the difference between the total energies of the N − 1 electron and N electron states, while EA is the difference between the total energies of the N electron and N + 1 electron states [43].

Table 5

Chemical reactivity descriptors (unit: eV)

EntriesC4mim+C4mimBrC4OHmim+C4OHmimBrC4NH2mim+C4NH2mimBr
Hardness (η)3.331.833.241.542.841.94
Softness (σ)0.150.270.150.330.180.26
Electrophilicity (ω)10.752.579.854.2710.042.63
Chemical potential (μ)−8.46–3.14−7.99–3.89−7.55–3.22
Electronegativity (χ)8.463.147.993.897.553.22
Ionization potential (I)11.794.9611.235.4210.395.16
(13.67)(7.59)(13.17)(7.81)(12.58)(7.50)
Electron affinity (A)5.131.314.752.354.711.28
(3.23)(0.11)(2.93)(0.13)(2.92)(0.06)

The hardness of a given species shows the extent of its electron cloud distortion in the electric field. The hardness order is shown below. The softness order was opposite to the hardness order.

C4mim+>C4OHmim+>C4NH2mim+>C4NH2mimBr>C4mimBr>C4OHmimBr

Cations are harder than ion pairs. Cations implied higher stability and opposing charge transfer. Ion pairs are more reactive than cations.

4 Conclusions

According to our results, the following conclusions could be drawn. The conformations of C4mim+, C4OHmim+, and C4NH2mim+ were fully searched by using the CONFLEX method. The introduction of the amino/hydroxyl group changes the special distributions of the alkyl chain. The Br anion is flexible around the cation. When Br is in the planar place with the ring, the geometry has the most stable structure. QTAIM analysis shows the nature of intramolecular interactions, particularly for hydrogen bonds. The computed values of ion-pair bonding energy show that the introduction of the amino/hydroxyl group attached to the butyl side chain in the cation has a little effect on the value of the binding energy. The NBO analysis displays the strong electron delocalization on the imidazolium ring. The largest intramolecular interaction comes from the orbital overlap between n(N1) and π*(N4–C5) as for the studied compounds. The second-largest interaction comes from the orbital overlap between n(N1) and π*(C2–C3). It is worth noting that the interaction of n(2)O and σ* (C10–H25), n(1)N11 and σ*(C10–H25) is 6.59 and 6.52 kcal/mol, respectively. The energy values of FMOs are related to the molecular global quantum descriptors. To design the task-specific ILs, the introduction of the functional group such as amino/hydroxyl is a good way at the starting point.

  1. Conflict of interest: The authors declare no conflict of interest.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 21505103) and Shaanxi Provincial Education Department (No. 17JK0606). The authors also appreciate the modern analysis and testing center of Xi’an Shiyou University for its hypercomputation.

References

[1] Wilkes JS. A short history of ionic liquids – from molten salts to neoteric solvents. Green Chem. 2002;4(2):73–80.10.1039/b110838gSearch in Google Scholar

[2] Brennecke JF, Maginn EJ. Ionic liquids: innovative fluids for chemical processing. AIChE J. 2002;47(11):2384–9.10.1002/aic.690471102Search in Google Scholar

[3] Marzouk AA, Vagif MA, Avtandil HT, Shaaban KM. Synthesis of 2,4,5-triphenyl imidazole derivatives using diethyl ammonium hydrogen phosphate as green, fast and reusable catalyst. World J Org Chem. 2013;1(1):6–10.Search in Google Scholar

[4] Welton T. Room-temperature ionic liquids: solvents for synthesis and catalysis. Chem Rev. 1999;99(8):2071–83.10.1021/cr980032tSearch in Google Scholar

[5] Rogers RD, Seddon KR. Ionic liquids–solvents of the future? Science. 2003;302(5646):792–3.10.1126/science.1090313Search in Google Scholar

[6] Plechkova NV, Seddon KR. Applications of ionic liquids in the chemical industry. Chem Soc Rev. 2008;37(1):123–7.10.1039/B006677JSearch in Google Scholar

[7] Olivier-Bourbigou H, Magna L, Morvan D. Ionic liquids and catalysis: recent progress from knowledge to applications. Appl Catal A. 2010;373(1–2):1–55.10.1016/j.apcata.2009.10.008Search in Google Scholar

[8] Zhao H, Malhotra S. Applications of ionic liquids in organic synthesis. Aldrichimica Acta. 2002;35(3):75–83.10.1016/S0003-2670(01)01543-4Search in Google Scholar

[9] Jared LA, Daniel WA, Wei GT. Ionic liquids in analytical chemistry. Anal Chem. 2006;78(9):2892–902.10.1021/ac069394oSearch in Google Scholar PubMed

[10] Pate DD, Lee JM. Applications of ionic liquids. Chem Rec. 2012;12(3):329–55.10.1002/tcr.201100036Search in Google Scholar PubMed

[11] Holbrey JD, Seddon KR. Ionic liquids. Clean Products Process. 1999;1:223–6.10.1007/s100980050036Search in Google Scholar

[12] Davis JH. Task-specific ionic liquids. Chem Lett. 2004;33(9):1072–7.10.1002/chin.200501222Search in Google Scholar

[13] Deetlefs M, Seddon KR, Shara M. Predicting physical properties of ionic liquids. Phys Chem Chem Phys. 2006;8(5):642–9.10.1039/B513453FSearch in Google Scholar

[14] Zhang SJ, Sun N, He XZ, Lu XM, Zhang XP. Physical properties of ionic liquids: database and evaluation. J Phys Chem Ref Data. 2006;35(4):1475.10.1063/1.2204959Search in Google Scholar

[15] Morrow TI, Maginn EJ. Molecular dynamics study of the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate. J Phys Chem B. 2002;106(49):12807–13.10.1021/jp0267003Search in Google Scholar

[16] Hanke CG, Lynden-BellR MA. A simulation study of water−dialkylimidazolium ionic liquid mixtures. J Phys Chem B. 2003;107(39):10873–7.10.1021/jp034221dSearch in Google Scholar

[17] Wang Y, Li H, Han S. The chemical nature of the C–H⊕⋯ X−(X = Cl or Br) interaction in imidazolium halide ionic liquids. J Chem Phys. 2006;124(4):044504.10.1063/1.2161174Search in Google Scholar PubMed

[18] Sun J, Zhang SJ, Cheng WG, Ren JY. Hydroxyl-functionalized ionic liquid: a novel efficient catalyst for chemical fixation of CO2 to cyclic carbonate. Tetrahedron Lett. 2008;49(22):3588–91.10.1016/j.tetlet.2008.04.022Search in Google Scholar

[19] Yue S, Wang PP, Hao XJ, Zang SL. Dual amino-functionalized ionic liquids as efficient catalysts for carbonate synthesis from carbon dioxide and epoxide under solvent and cocatalyst-free conditions. J CO2 Utilization. 2017;21:238–46.10.1016/j.jcou.2017.07.017Search in Google Scholar

[20] Nataša VA, Radha DB, Robert S, Christian RW, Daniel B, Mario UG, et al. Insights form molecular simulations on structural organization and diffusive dynamics of an ionic liquid at solid and vacuum interfaces. J colloid interface Sci. 2019;553(1):350–63.10.1016/j.jcis.2019.06.017Search in Google Scholar PubMed

[21] Dmitry B, Jean-Philip P, Oleg B, Alexander Jr DM, Benoît R, Christian S. Molecular dynamics simulations of ionic liquids and electrolytes using polarizable force fields. Chem Rev. 2019;119(13):7940–45.10.1021/acs.chemrev.8b00763Search in Google Scholar PubMed PubMed Central

[22] Goto H, Osawa EJ. Corner flapping: a simple and fast algorithm for exha.ustive generation of ring conformations. J Am Chem Soc. 1989;111(24):8950–1.10.1021/ja00206a046Search in Google Scholar

[23] Goto H, Osawa EJ. An efficient algorithm for searching low-energy conformers of cyclic and acyclic molecules. J Chem Society Perkin Trans 2. 1993;2:187–98.10.1039/P29930000187Search in Google Scholar

[24] “Why Use CONFLEX”. Available from http://www.conflex.net/conflex_algorithm.htmlSearch in Google Scholar

[25] Goto H, Ohta K, Kamakura T, Obata S, Nakayama N, Matsumoto T, et al. Conflex Corp., Tokyo, Japan, 2018.Search in Google Scholar

[26] Halgren TA. Merck molecular force field. I. Basis, form, scope, parameterization, and performance of MMFF94. J Comput Chem. 1996;17(5–6):490–519.10.1002/(SICI)1096-987X(199604)17:5/6<490::AID-JCC1>3.0.CO;2-PSearch in Google Scholar

[27] Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR, et al. Gaussian 16, Revision B.01. Gaussian, Inc., Wallingford CT, 2016.Search in Google Scholar

[28] Becke AD. A new mixing of Hartree–Fock and local density‐functional theories. J Chem Phys. 1993;98(2):1372.10.1063/1.464304Search in Google Scholar

[29] Becke AD. Density-functional exchange-energy approximation with correct asymptotic behavior. Phys Rev A. 1988;38(6):3098.10.1103/PhysRevA.38.3098Search in Google Scholar

[30] Zhao YS, Pan MG, Kang XJ, Tu WH, Gao HS, Zhang XP. Gas separation by ionic liquids: a theoretical study. Chem Eng Sci. 2018;189:43–55.10.1016/j.ces.2018.05.044Search in Google Scholar

[31] Dong K, Cao Y, Yang Q, Zhang S, Xing H, Ren Q. Role of hydrogen bonds in ionic-liquid-mediated extraction of natural bioactive homologues. Ind Eng Chem Res. 2012;51(14):5299–308.10.1021/ie203044mSearch in Google Scholar

[32] Parveen F, Patra T, Upadhyayula S. Hydrolysis of microcrystalline cellulose using functionalized Bronsted acidic ionic liquids – a comparative study. Carbohydr Polym. 2016;135:280–4.10.1016/j.carbpol.2015.08.039Search in Google Scholar

[33] Boys SF, Bernardi F. The calculation of small molecular interactions by the differences of separate total energies some procedures with reduced errors. Mol Phys. 1970;19(4):553–66.10.1080/00268977000101561Search in Google Scholar

[34] Glendening ED, Reed AE, Carpenter JE, Weinhold F. NBO Version 3.1. Pittsburgh, PA: Gaussian Inc.Search in Google Scholar

[35] Bader RFW. A quantum theory of molecular structure and its applications. Chem Rev. 1991;91(5):893–928.10.1021/cr00005a013Search in Google Scholar

[36] Lu T, Chen FW. Multiwfn: a multifunctional wavefuntion analyzer. J Comput Chem. 2012;33(5):580–92.10.1002/jcc.22885Search in Google Scholar

[37] Humphrey W, Dalke A, Schulten K. VMD – visual molecular dynamics. J Mol Graph Model. 1996;14(1):33–8.10.1016/0263-7855(96)00018-5Search in Google Scholar

[38] Jia XG, Hu XL, Su KH, Wang WZ, Gu XF. Analysis of the electronic structure of 1-(4-aminobutyl)-3-methyl imidazolium chloride via DFT method. Chin J Struct Chem. 2019;38(1):53–7.Search in Google Scholar

[39] Bayat M, Yaghoobi F, Salehzadeh S. A theoretical study on the interaction of [Al(H2O)6]3+ and [Mg(H2O)6]2+ cations with fullerene (C60), coronene and benzene π-systems. Polyhedron. 2011;30(17):2809.10.1016/j.poly.2011.08.017Search in Google Scholar

[40] Espinosa E, Molins E, Lecomte C. Hydrogen bond strength revealed by topological analyses of experimentally observed electron densities. Chem Phys Lett. 1998;285(3–4):170–3.10.1016/S0009-2614(98)00036-0Search in Google Scholar

[41] Jeffrey GA. An Introduction to Hydrogen Bonding. Oxford, UK: Oxford University Press; 1997.Search in Google Scholar

[42] Miehlich B, Savin A, Stoll H, Preuss H. Results obtained with the correlation energy density functionals of becke and Lee, Yang and Parr. Chem Phys Lett. 1989;157(3):200–6.10.1016/0009-2614(89)87234-3Search in Google Scholar

[43] Bredas JL. Mind the gap. Mater Horiz. 2014;1:17–9.10.1039/C3MH00098BSearch in Google Scholar

Received: 2020-02-03
Revised: 2020-04-01
Accepted: 2020-04-08
Published Online: 2020-06-09

© 2020 Xiaoling Hu et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Regular Articles
  2. Electrochemical antioxidant screening and evaluation based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE)
  3. Kinetic models of the extraction of vanillic acid from pumpkin seeds
  4. On the maximum ABC index of bipartite graphs without pendent vertices
  5. Estimation of the total antioxidant potential in the meat samples using thin-layer chromatography
  6. Molecular dynamics simulation of sI methane hydrate under compression and tension
  7. Spatial distribution and potential ecological risk assessment of some trace elements in sediments and grey mangrove (Avicennia marina) along the Arabian Gulf coast, Saudi Arabia
  8. Amino-functionalized graphene oxide for Cr(VI), Cu(II), Pb(II) and Cd(II) removal from industrial wastewater
  9. Chemical composition and in vitro activity of Origanum vulgare L., Satureja hortensis L., Thymus serpyllum L. and Thymus vulgaris L. essential oils towards oral isolates of Candida albicans and Candida glabrata
  10. Effect of excess Fluoride consumption on Urine-Serum Fluorides, Dental state and Thyroid Hormones among children in “Talab Sarai” Punjab Pakistan
  11. Design, Synthesis and Characterization of Novel Isoxazole Tagged Indole Hybrid Compounds
  12. Comparison of kinetic and enzymatic properties of intracellular phosphoserine aminotransferases from alkaliphilic and neutralophilic bacteria
  13. Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
  14. Ducrosia ismaelis Asch. essential oil: chemical composition profile and anticancer, antimicrobial and antioxidant potential assessment
  15. DFT calculations as an efficient tool for prediction of Raman and infra-red spectra and activities of newly synthesized cathinones
  16. Influence of Chemical Osmosis on Solute Transport and Fluid Velocity in Clay Soils
  17. A New fatty acid and some triterpenoids from propolis of Nkambe (North-West Region, Cameroon) and evaluation of the antiradical scavenging activity of their extracts
  18. Antiplasmodial Activity of Stigmastane Steroids from Dryobalanops oblongifolia Stem Bark
  19. Rapid identification of direct-acting pancreatic protectants from Cyclocarya paliurus leaves tea by the method of serum pharmacochemistry combined with target cell extraction
  20. Immobilization of Pseudomonas aeruginosa static biomass on eggshell powder for on-line preconcentration and determination of Cr (VI)
  21. Assessment of methyl 2-({[(4,6-dimethoxypyrimidin-2-yl)carbamoyl] sulfamoyl}methyl)benzoate through biotic and abiotic degradation modes
  22. Stability of natural polyphenol fisetin in eye drops Stability of fisetin in eye drops
  23. Production of a bioflocculant by using activated sludge and its application in Pb(II) removal from aqueous solution
  24. Molecular Properties of Carbon Crystal Cubic Structures
  25. Synthesis and characterization of calcium carbonate whisker from yellow phosphorus slag
  26. Study on the interaction between catechin and cholesterol by the density functional theory
  27. Analysis of some pharmaceuticals in the presence of their synthetic impurities by applying hybrid micelle liquid chromatography
  28. Two mixed-ligand coordination polymers based on 2,5-thiophenedicarboxylic acid and flexible N-donor ligands: the protective effect on periodontitis via reducing the release of IL-1β and TNF-α
  29. Incorporation of silver stearate nanoparticles in methacrylate polymeric monoliths for hemeprotein isolation
  30. Development of ultrasound-assisted dispersive solid-phase microextraction based on mesoporous carbon coated with silica@iron oxide nanocomposite for preconcentration of Te and Tl in natural water systems
  31. N,N′-Bis[2-hydroxynaphthylidene]/[2-methoxybenzylidene]amino]oxamides and their divalent manganese complexes: Isolation, spectral characterization, morphology, antibacterial and cytotoxicity against leukemia cells
  32. Determination of the content of selected trace elements in Polish commercial fruit juices and health risk assessment
  33. Diorganotin(iv) benzyldithiocarbamate complexes: synthesis, characterization, and thermal and cytotoxicity study
  34. Keratin 17 is induced in prurigo nodularis lesions
  35. Anticancer, antioxidant, and acute toxicity studies of a Saudi polyherbal formulation, PHF5
  36. LaCoO3 perovskite-type catalysts in syngas conversion
  37. Comparative studies of two vegetal extracts from Stokesia laevis and Geranium pratense: polyphenol profile, cytotoxic effect and antiproliferative activity
  38. Fragmentation pattern of certain isatin–indole antiproliferative conjugates with application to identify their in vitro metabolic profiles in rat liver microsomes by liquid chromatography tandem mass spectrometry
  39. Investigation of polyphenol profile, antioxidant activity and hepatoprotective potential of Aconogonon alpinum (All.) Schur roots
  40. Lead discovery of a guanidinyl tryptophan derivative on amyloid cascade inhibition
  41. Physicochemical evaluation of the fruit pulp of Opuntia spp growing in the Mediterranean area under hard climate conditions
  42. Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids
  43. New Schiff bases of 2-(quinolin-8-yloxy)acetohydrazide and their Cu(ii), and Zn(ii) metal complexes: their in vitro antimicrobial potentials and in silico physicochemical and pharmacokinetics properties
  44. Treatment of adhesions after Achilles tendon injury using focused ultrasound with targeted bFGF plasmid-loaded cationic microbubbles
  45. Synthesis of orotic acid derivatives and their effects on stem cell proliferation
  46. Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis
  47. Fe3O4@urea/HITh-SO3H as an efficient and reusable catalyst for the solvent-free synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives
  48. Adsorption kinetic characteristics of molybdenum in yellow-brown soil in response to pH and phosphate
  49. Enhancement of thermal properties of bio-based microcapsules intended for textile applications
  50. Exploring the effect of khat (Catha edulis) chewing on the pharmacokinetics of the antiplatelet drug clopidogrel in rats using the newly developed LC-MS/MS technique
  51. A green strategy for obtaining anthraquinones from Rheum tanguticum by subcritical water
  52. Cadmium (Cd) chloride affects the nutrient uptake and Cd-resistant bacterium reduces the adsorption of Cd in muskmelon plants
  53. Removal of H2S by vermicompost biofilter and analysis on bacterial community
  54. Structural cytotoxicity relationship of 2-phenoxy(thiomethyl)pyridotriazolopyrimidines: Quantum chemical calculations and statistical analysis
  55. A self-breaking supramolecular plugging system as lost circulation material in oilfield
  56. Synthesis, characterization, and pharmacological evaluation of thiourea derivatives
  57. Application of drug–metal ion interaction principle in conductometric determination of imatinib, sorafenib, gefitinib and bosutinib
  58. Synthesis and characterization of a novel chitosan-grafted-polyorthoethylaniline biocomposite and utilization for dye removal from water
  59. Optimisation of urine sample preparation for shotgun proteomics
  60. DFT investigations on arylsulphonyl pyrazole derivatives as potential ligands of selected kinases
  61. Treatment of Parkinson’s disease using focused ultrasound with GDNF retrovirus-loaded microbubbles to open the blood–brain barrier
  62. New derivatives of a natural nordentatin
  63. Fluorescence biomarkers of malignant melanoma detectable in urine
  64. Study of the remediation effects of passivation materials on Pb-contaminated soil
  65. Saliva proteomic analysis reveals possible biomarkers of renal cell carcinoma
  66. Withania frutescens: Chemical characterization, analgesic, anti-inflammatory, and healing activities
  67. Design, synthesis and pharmacological profile of (−)-verbenone hydrazones
  68. Synthesis of magnesium carbonate hydrate from natural talc
  69. Stability-indicating HPLC-DAD assay for simultaneous quantification of hydrocortisone 21 acetate, dexamethasone, and fluocinolone acetonide in cosmetics
  70. A novel lactose biosensor based on electrochemically synthesized 3,4-ethylenedioxythiophene/thiophene (EDOT/Th) copolymer
  71. Citrullus colocynthis (L.) Schrad: Chemical characterization, scavenging and cytotoxic activities
  72. Development and validation of a high performance liquid chromatography/diode array detection method for estrogen determination: Application to residual analysis in meat products
  73. PCSK9 concentrations in different stages of subclinical atherosclerosis and their relationship with inflammation
  74. Development of trace analysis for alkyl methanesulfonates in the delgocitinib drug substance using GC-FID and liquid–liquid extraction with ionic liquid
  75. Electrochemical evaluation of the antioxidant capacity of natural compounds on glassy carbon electrode modified with guanine-, polythionine-, and nitrogen-doped graphene
  76. A Dy(iii)–organic framework as a fluorescent probe for highly selective detection of picric acid and treatment activity on human lung cancer cells
  77. A Zn(ii)–organic cage with semirigid ligand for solvent-free cyanosilylation and inhibitory effect on ovarian cancer cell migration and invasion ability via regulating mi-RNA16 expression
  78. Polyphenol content and antioxidant activities of Prunus padus L. and Prunus serotina L. leaves: Electrochemical and spectrophotometric approach and their antimicrobial properties
  79. The combined use of GC, PDSC and FT-IR techniques to characterize fat extracted from commercial complete dry pet food for adult cats
  80. MALDI-TOF MS profiling in the discovery and identification of salivary proteomic patterns of temporomandibular joint disorders
  81. Concentrations of dioxins, furans and dioxin-like PCBs in natural animal feed additives
  82. Structure and some physicochemical and functional properties of water treated under ammonia with low-temperature low-pressure glow plasma of low frequency
  83. Mesoscale nanoparticles encapsulated with emodin for targeting antifibrosis in animal models
  84. Amine-functionalized magnetic activated carbon as an adsorbent for preconcentration and determination of acidic drugs in environmental water samples using HPLC-DAD
  85. Antioxidant activity as a response to cadmium pollution in three durum wheat genotypes differing in salt-tolerance
  86. A promising naphthoquinone [8-hydroxy-2-(2-thienylcarbonyl)naphtho[2,3-b]thiophene-4,9-dione] exerts anti-colorectal cancer activity through ferroptosis and inhibition of MAPK signaling pathway based on RNA sequencing
  87. Synthesis and efficacy of herbicidal ionic liquids with chlorsulfuron as the anion
  88. Effect of isovalent substitution on the crystal structure and properties of two-slab indates BaLa2−xSmxIn2O7
  89. Synthesis, spectral and thermo-kinetics explorations of Schiff-base derived metal complexes
  90. An improved reduction method for phase stability testing in the single-phase region
  91. Comparative analysis of chemical composition of some commercially important fishes with an emphasis on various Malaysian diets
  92. Development of a solventless stir bar sorptive extraction/thermal desorption large volume injection capillary gas chromatographic-mass spectrometric method for ultra-trace determination of pyrethroids pesticides in river and tap water samples
  93. A turbidity sensor development based on NL-PI observers: Experimental application to the control of a Sinaloa’s River Spirulina maxima cultivation
  94. Deep desulfurization of sintering flue gas in iron and steel works based on low-temperature oxidation
  95. Investigations of metallic elements and phenolics in Chinese medicinal plants
  96. Influence of site-classification approach on geochemical background values
  97. Effects of ageing on the surface characteristics and Cu(ii) adsorption behaviour of rice husk biochar in soil
  98. Adsorption and sugarcane-bagasse-derived activated carbon-based mitigation of 1-[2-(2-chloroethoxy)phenyl]sulfonyl-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl) urea-contaminated soils
  99. Antimicrobial and antifungal activities of bifunctional cooper(ii) complexes with non-steroidal anti-inflammatory drugs, flufenamic, mefenamic and tolfenamic acids and 1,10-phenanthroline
  100. Application of selenium and silicon to alleviate short-term drought stress in French marigold (Tagetes patula L.) as a model plant species
  101. Screening and analysis of xanthine oxidase inhibitors in jute leaves and their protective effects against hydrogen peroxide-induced oxidative stress in cells
  102. Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease
  103. A study of in vitro metabolism and cytotoxicity of mephedrone and methoxetamine in human and pig liver models using GC/MS and LC/MS analyses
  104. A new phenyl alkyl ester and a new combretin triterpene derivative from Combretum fragrans F. Hoffm (Combretaceae) and antiproliferative activity
  105. Erratum
  106. Erratum to: A one-step incubation ELISA kit for rapid determination of dibutyl phthalate in water, beverage and liquor
  107. Review Articles
  108. Sinoporphyrin sodium, a novel sensitizer for photodynamic and sonodynamic therapy
  109. Natural products isolated from Casimiroa
  110. Plant description, phytochemical constituents and bioactivities of Syzygium genus: A review
  111. Evaluation of elastomeric heat shielding materials as insulators for solid propellant rocket motors: A short review
  112. Special Issue on Applied Biochemistry and Biotechnology 2019
  113. An overview of Monascus fermentation processes for monacolin K production
  114. Study on online soft sensor method of total sugar content in chlorotetracycline fermentation tank
  115. Studies on the Anti-Gouty Arthritis and Anti-hyperuricemia Properties of Astilbin in Animal Models
  116. Effects of organic fertilizer on water use, photosynthetic characteristics, and fruit quality of pear jujube in northern Shaanxi
  117. Characteristics of the root exudate release system of typical plants in plateau lakeside wetland under phosphorus stress conditions
  118. Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River
  119. Composition and diurnal variation of floral scent emission in Rosa rugosa Thunb. and Tulipa gesneriana L.
  120. Preparation of a novel ginkgolide B niosomal composite drug
  121. The degradation, biodegradability and toxicity evaluation of sulfamethazine antibiotics by gamma radiation
  122. Special issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  123. Insight into the cadmium and zinc binding potential of humic acids derived from composts by EEM spectra combined with PARAFAC analysis
  124. Source apportionment of soil contamination based on multivariate receptor and robust geostatistics in a typical rural–urban area, Wuhan city, middle China
  125. Special Issue on 13th JCC 2018
  126. The Role of H2C2O4 and Na2CO3 as Precipitating Agents on The Physichochemical Properties and Photocatalytic Activity of Bismuth Oxide
  127. Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization
  128. Topical Issue on Agriculture
  129. Size-dependent growth kinetics of struvite crystals in wastewater with calcium ions
  130. The effect of silica-calcite sedimentary rock contained in the chicken broiler diet on the overall quality of chicken muscles
  131. Physicochemical properties of selected herbicidal products containing nicosulfuron as an active ingredient
  132. Lycopene in tomatoes and tomato products
  133. Fluorescence in the assessment of the share of a key component in the mixing of feed
  134. Sulfur application alleviates chromium stress in maize and wheat
  135. Effectiveness of removal of sulphur compounds from the air after 3 years of biofiltration with a mixture of compost soil, peat, coconut fibre and oak bark
  136. Special Issue on the 4th Green Chemistry 2018
  137. Study and fire test of banana fibre reinforced composites with flame retardance properties
  138. Special Issue on the International conference CosCI 2018
  139. Disintegration, In vitro Dissolution, and Drug Release Kinetics Profiles of k-Carrageenan-based Nutraceutical Hard-shell Capsules Containing Salicylamide
  140. Synthesis of amorphous aluminosilicate from impure Indonesian kaolin
  141. Special Issue on the International Conf on Science, Applied Science, Teaching and Education 2019
  142. Functionalization of Congo red dye as a light harvester on solar cell
  143. The effect of nitrite food preservatives added to se’i meat on the expression of wild-type p53 protein
  144. Biocompatibility and osteoconductivity of scaffold porous composite collagen–hydroxyapatite based coral for bone regeneration
  145. Special Issue on the Joint Science Congress of Materials and Polymers (ISCMP 2019)
  146. Effect of natural boron mineral use on the essential oil ratio and components of Musk Sage (Salvia sclarea L.)
  147. A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent
  148. A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study
  149. Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study
  150. Special Issue on Chemistry Today for Tomorrow 2019
  151. Diabetes mellitus type 2: Exploratory data analysis based on clinical reading
  152. Multivariate analysis for the classification of copper–lead and copper–zinc glasses
  153. Special Issue on Advances in Chemistry and Polymers
  154. The spatial and temporal distribution of cationic and anionic radicals in early embryo implantation
  155. Special Issue on 3rd IC3PE 2020
  156. Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications
  157. Special Issue on IC3PE 2018/2019 Conference
  158. Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production
  159. Advancing biodiesel production from microalgae Spirulina sp. by a simultaneous extraction–transesterification process using palm oil as a co-solvent of methanol
  160. Topical Issue on Applications of Mathematics in Chemistry
  161. Omega and the related counting polynomials of some chemical structures
  162. M-polynomial and topological indices of zigzag edge coronoid fused by starphene
https://doi.org/10.1515/chem-2020-0068
Keywords for this article
ionic liquids; conformations; frontier molecular orbitals; intramolecular interactions
Creative Commons
BY 4.0

Articles in the same Issue

  1. Regular Articles
  2. Electrochemical antioxidant screening and evaluation based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE)
  3. Kinetic models of the extraction of vanillic acid from pumpkin seeds
  4. On the maximum ABC index of bipartite graphs without pendent vertices
  5. Estimation of the total antioxidant potential in the meat samples using thin-layer chromatography
  6. Molecular dynamics simulation of sI methane hydrate under compression and tension
  7. Spatial distribution and potential ecological risk assessment of some trace elements in sediments and grey mangrove (Avicennia marina) along the Arabian Gulf coast, Saudi Arabia
  8. Amino-functionalized graphene oxide for Cr(VI), Cu(II), Pb(II) and Cd(II) removal from industrial wastewater
  9. Chemical composition and in vitro activity of Origanum vulgare L., Satureja hortensis L., Thymus serpyllum L. and Thymus vulgaris L. essential oils towards oral isolates of Candida albicans and Candida glabrata
  10. Effect of excess Fluoride consumption on Urine-Serum Fluorides, Dental state and Thyroid Hormones among children in “Talab Sarai” Punjab Pakistan
  11. Design, Synthesis and Characterization of Novel Isoxazole Tagged Indole Hybrid Compounds
  12. Comparison of kinetic and enzymatic properties of intracellular phosphoserine aminotransferases from alkaliphilic and neutralophilic bacteria
  13. Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
  14. Ducrosia ismaelis Asch. essential oil: chemical composition profile and anticancer, antimicrobial and antioxidant potential assessment
  15. DFT calculations as an efficient tool for prediction of Raman and infra-red spectra and activities of newly synthesized cathinones
  16. Influence of Chemical Osmosis on Solute Transport and Fluid Velocity in Clay Soils
  17. A New fatty acid and some triterpenoids from propolis of Nkambe (North-West Region, Cameroon) and evaluation of the antiradical scavenging activity of their extracts
  18. Antiplasmodial Activity of Stigmastane Steroids from Dryobalanops oblongifolia Stem Bark
  19. Rapid identification of direct-acting pancreatic protectants from Cyclocarya paliurus leaves tea by the method of serum pharmacochemistry combined with target cell extraction
  20. Immobilization of Pseudomonas aeruginosa static biomass on eggshell powder for on-line preconcentration and determination of Cr (VI)
  21. Assessment of methyl 2-({[(4,6-dimethoxypyrimidin-2-yl)carbamoyl] sulfamoyl}methyl)benzoate through biotic and abiotic degradation modes
  22. Stability of natural polyphenol fisetin in eye drops Stability of fisetin in eye drops
  23. Production of a bioflocculant by using activated sludge and its application in Pb(II) removal from aqueous solution
  24. Molecular Properties of Carbon Crystal Cubic Structures
  25. Synthesis and characterization of calcium carbonate whisker from yellow phosphorus slag
  26. Study on the interaction between catechin and cholesterol by the density functional theory
  27. Analysis of some pharmaceuticals in the presence of their synthetic impurities by applying hybrid micelle liquid chromatography
  28. Two mixed-ligand coordination polymers based on 2,5-thiophenedicarboxylic acid and flexible N-donor ligands: the protective effect on periodontitis via reducing the release of IL-1β and TNF-α
  29. Incorporation of silver stearate nanoparticles in methacrylate polymeric monoliths for hemeprotein isolation
  30. Development of ultrasound-assisted dispersive solid-phase microextraction based on mesoporous carbon coated with silica@iron oxide nanocomposite for preconcentration of Te and Tl in natural water systems
  31. N,N′-Bis[2-hydroxynaphthylidene]/[2-methoxybenzylidene]amino]oxamides and their divalent manganese complexes: Isolation, spectral characterization, morphology, antibacterial and cytotoxicity against leukemia cells
  32. Determination of the content of selected trace elements in Polish commercial fruit juices and health risk assessment
  33. Diorganotin(iv) benzyldithiocarbamate complexes: synthesis, characterization, and thermal and cytotoxicity study
  34. Keratin 17 is induced in prurigo nodularis lesions
  35. Anticancer, antioxidant, and acute toxicity studies of a Saudi polyherbal formulation, PHF5
  36. LaCoO3 perovskite-type catalysts in syngas conversion
  37. Comparative studies of two vegetal extracts from Stokesia laevis and Geranium pratense: polyphenol profile, cytotoxic effect and antiproliferative activity
  38. Fragmentation pattern of certain isatin–indole antiproliferative conjugates with application to identify their in vitro metabolic profiles in rat liver microsomes by liquid chromatography tandem mass spectrometry
  39. Investigation of polyphenol profile, antioxidant activity and hepatoprotective potential of Aconogonon alpinum (All.) Schur roots
  40. Lead discovery of a guanidinyl tryptophan derivative on amyloid cascade inhibition
  41. Physicochemical evaluation of the fruit pulp of Opuntia spp growing in the Mediterranean area under hard climate conditions
  42. Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids
  43. New Schiff bases of 2-(quinolin-8-yloxy)acetohydrazide and their Cu(ii), and Zn(ii) metal complexes: their in vitro antimicrobial potentials and in silico physicochemical and pharmacokinetics properties
  44. Treatment of adhesions after Achilles tendon injury using focused ultrasound with targeted bFGF plasmid-loaded cationic microbubbles
  45. Synthesis of orotic acid derivatives and their effects on stem cell proliferation
  46. Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis
  47. Fe3O4@urea/HITh-SO3H as an efficient and reusable catalyst for the solvent-free synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives
  48. Adsorption kinetic characteristics of molybdenum in yellow-brown soil in response to pH and phosphate
  49. Enhancement of thermal properties of bio-based microcapsules intended for textile applications
  50. Exploring the effect of khat (Catha edulis) chewing on the pharmacokinetics of the antiplatelet drug clopidogrel in rats using the newly developed LC-MS/MS technique
  51. A green strategy for obtaining anthraquinones from Rheum tanguticum by subcritical water
  52. Cadmium (Cd) chloride affects the nutrient uptake and Cd-resistant bacterium reduces the adsorption of Cd in muskmelon plants
  53. Removal of H2S by vermicompost biofilter and analysis on bacterial community
  54. Structural cytotoxicity relationship of 2-phenoxy(thiomethyl)pyridotriazolopyrimidines: Quantum chemical calculations and statistical analysis
  55. A self-breaking supramolecular plugging system as lost circulation material in oilfield
  56. Synthesis, characterization, and pharmacological evaluation of thiourea derivatives
  57. Application of drug–metal ion interaction principle in conductometric determination of imatinib, sorafenib, gefitinib and bosutinib
  58. Synthesis and characterization of a novel chitosan-grafted-polyorthoethylaniline biocomposite and utilization for dye removal from water
  59. Optimisation of urine sample preparation for shotgun proteomics
  60. DFT investigations on arylsulphonyl pyrazole derivatives as potential ligands of selected kinases
  61. Treatment of Parkinson’s disease using focused ultrasound with GDNF retrovirus-loaded microbubbles to open the blood–brain barrier
  62. New derivatives of a natural nordentatin
  63. Fluorescence biomarkers of malignant melanoma detectable in urine
  64. Study of the remediation effects of passivation materials on Pb-contaminated soil
  65. Saliva proteomic analysis reveals possible biomarkers of renal cell carcinoma
  66. Withania frutescens: Chemical characterization, analgesic, anti-inflammatory, and healing activities
  67. Design, synthesis and pharmacological profile of (−)-verbenone hydrazones
  68. Synthesis of magnesium carbonate hydrate from natural talc
  69. Stability-indicating HPLC-DAD assay for simultaneous quantification of hydrocortisone 21 acetate, dexamethasone, and fluocinolone acetonide in cosmetics
  70. A novel lactose biosensor based on electrochemically synthesized 3,4-ethylenedioxythiophene/thiophene (EDOT/Th) copolymer
  71. Citrullus colocynthis (L.) Schrad: Chemical characterization, scavenging and cytotoxic activities
  72. Development and validation of a high performance liquid chromatography/diode array detection method for estrogen determination: Application to residual analysis in meat products
  73. PCSK9 concentrations in different stages of subclinical atherosclerosis and their relationship with inflammation
  74. Development of trace analysis for alkyl methanesulfonates in the delgocitinib drug substance using GC-FID and liquid–liquid extraction with ionic liquid
  75. Electrochemical evaluation of the antioxidant capacity of natural compounds on glassy carbon electrode modified with guanine-, polythionine-, and nitrogen-doped graphene
  76. A Dy(iii)–organic framework as a fluorescent probe for highly selective detection of picric acid and treatment activity on human lung cancer cells
  77. A Zn(ii)–organic cage with semirigid ligand for solvent-free cyanosilylation and inhibitory effect on ovarian cancer cell migration and invasion ability via regulating mi-RNA16 expression
  78. Polyphenol content and antioxidant activities of Prunus padus L. and Prunus serotina L. leaves: Electrochemical and spectrophotometric approach and their antimicrobial properties
  79. The combined use of GC, PDSC and FT-IR techniques to characterize fat extracted from commercial complete dry pet food for adult cats
  80. MALDI-TOF MS profiling in the discovery and identification of salivary proteomic patterns of temporomandibular joint disorders
  81. Concentrations of dioxins, furans and dioxin-like PCBs in natural animal feed additives
  82. Structure and some physicochemical and functional properties of water treated under ammonia with low-temperature low-pressure glow plasma of low frequency
  83. Mesoscale nanoparticles encapsulated with emodin for targeting antifibrosis in animal models
  84. Amine-functionalized magnetic activated carbon as an adsorbent for preconcentration and determination of acidic drugs in environmental water samples using HPLC-DAD
  85. Antioxidant activity as a response to cadmium pollution in three durum wheat genotypes differing in salt-tolerance
  86. A promising naphthoquinone [8-hydroxy-2-(2-thienylcarbonyl)naphtho[2,3-b]thiophene-4,9-dione] exerts anti-colorectal cancer activity through ferroptosis and inhibition of MAPK signaling pathway based on RNA sequencing
  87. Synthesis and efficacy of herbicidal ionic liquids with chlorsulfuron as the anion
  88. Effect of isovalent substitution on the crystal structure and properties of two-slab indates BaLa2−xSmxIn2O7
  89. Synthesis, spectral and thermo-kinetics explorations of Schiff-base derived metal complexes
  90. An improved reduction method for phase stability testing in the single-phase region
  91. Comparative analysis of chemical composition of some commercially important fishes with an emphasis on various Malaysian diets
  92. Development of a solventless stir bar sorptive extraction/thermal desorption large volume injection capillary gas chromatographic-mass spectrometric method for ultra-trace determination of pyrethroids pesticides in river and tap water samples
  93. A turbidity sensor development based on NL-PI observers: Experimental application to the control of a Sinaloa’s River Spirulina maxima cultivation
  94. Deep desulfurization of sintering flue gas in iron and steel works based on low-temperature oxidation
  95. Investigations of metallic elements and phenolics in Chinese medicinal plants
  96. Influence of site-classification approach on geochemical background values
  97. Effects of ageing on the surface characteristics and Cu(ii) adsorption behaviour of rice husk biochar in soil
  98. Adsorption and sugarcane-bagasse-derived activated carbon-based mitigation of 1-[2-(2-chloroethoxy)phenyl]sulfonyl-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl) urea-contaminated soils
  99. Antimicrobial and antifungal activities of bifunctional cooper(ii) complexes with non-steroidal anti-inflammatory drugs, flufenamic, mefenamic and tolfenamic acids and 1,10-phenanthroline
  100. Application of selenium and silicon to alleviate short-term drought stress in French marigold (Tagetes patula L.) as a model plant species
  101. Screening and analysis of xanthine oxidase inhibitors in jute leaves and their protective effects against hydrogen peroxide-induced oxidative stress in cells
  102. Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease
  103. A study of in vitro metabolism and cytotoxicity of mephedrone and methoxetamine in human and pig liver models using GC/MS and LC/MS analyses
  104. A new phenyl alkyl ester and a new combretin triterpene derivative from Combretum fragrans F. Hoffm (Combretaceae) and antiproliferative activity
  105. Erratum
  106. Erratum to: A one-step incubation ELISA kit for rapid determination of dibutyl phthalate in water, beverage and liquor
  107. Review Articles
  108. Sinoporphyrin sodium, a novel sensitizer for photodynamic and sonodynamic therapy
  109. Natural products isolated from Casimiroa
  110. Plant description, phytochemical constituents and bioactivities of Syzygium genus: A review
  111. Evaluation of elastomeric heat shielding materials as insulators for solid propellant rocket motors: A short review
  112. Special Issue on Applied Biochemistry and Biotechnology 2019
  113. An overview of Monascus fermentation processes for monacolin K production
  114. Study on online soft sensor method of total sugar content in chlorotetracycline fermentation tank
  115. Studies on the Anti-Gouty Arthritis and Anti-hyperuricemia Properties of Astilbin in Animal Models
  116. Effects of organic fertilizer on water use, photosynthetic characteristics, and fruit quality of pear jujube in northern Shaanxi
  117. Characteristics of the root exudate release system of typical plants in plateau lakeside wetland under phosphorus stress conditions
  118. Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River
  119. Composition and diurnal variation of floral scent emission in Rosa rugosa Thunb. and Tulipa gesneriana L.
  120. Preparation of a novel ginkgolide B niosomal composite drug
  121. The degradation, biodegradability and toxicity evaluation of sulfamethazine antibiotics by gamma radiation
  122. Special issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  123. Insight into the cadmium and zinc binding potential of humic acids derived from composts by EEM spectra combined with PARAFAC analysis
  124. Source apportionment of soil contamination based on multivariate receptor and robust geostatistics in a typical rural–urban area, Wuhan city, middle China
  125. Special Issue on 13th JCC 2018
  126. The Role of H2C2O4 and Na2CO3 as Precipitating Agents on The Physichochemical Properties and Photocatalytic Activity of Bismuth Oxide
  127. Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization
  128. Topical Issue on Agriculture
  129. Size-dependent growth kinetics of struvite crystals in wastewater with calcium ions
  130. The effect of silica-calcite sedimentary rock contained in the chicken broiler diet on the overall quality of chicken muscles
  131. Physicochemical properties of selected herbicidal products containing nicosulfuron as an active ingredient
  132. Lycopene in tomatoes and tomato products
  133. Fluorescence in the assessment of the share of a key component in the mixing of feed
  134. Sulfur application alleviates chromium stress in maize and wheat
  135. Effectiveness of removal of sulphur compounds from the air after 3 years of biofiltration with a mixture of compost soil, peat, coconut fibre and oak bark
  136. Special Issue on the 4th Green Chemistry 2018
  137. Study and fire test of banana fibre reinforced composites with flame retardance properties
  138. Special Issue on the International conference CosCI 2018
  139. Disintegration, In vitro Dissolution, and Drug Release Kinetics Profiles of k-Carrageenan-based Nutraceutical Hard-shell Capsules Containing Salicylamide
  140. Synthesis of amorphous aluminosilicate from impure Indonesian kaolin
  141. Special Issue on the International Conf on Science, Applied Science, Teaching and Education 2019
  142. Functionalization of Congo red dye as a light harvester on solar cell
  143. The effect of nitrite food preservatives added to se’i meat on the expression of wild-type p53 protein
  144. Biocompatibility and osteoconductivity of scaffold porous composite collagen–hydroxyapatite based coral for bone regeneration
  145. Special Issue on the Joint Science Congress of Materials and Polymers (ISCMP 2019)
  146. Effect of natural boron mineral use on the essential oil ratio and components of Musk Sage (Salvia sclarea L.)
  147. A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent
  148. A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study
  149. Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study
  150. Special Issue on Chemistry Today for Tomorrow 2019
  151. Diabetes mellitus type 2: Exploratory data analysis based on clinical reading
  152. Multivariate analysis for the classification of copper–lead and copper–zinc glasses
  153. Special Issue on Advances in Chemistry and Polymers
  154. The spatial and temporal distribution of cationic and anionic radicals in early embryo implantation
  155. Special Issue on 3rd IC3PE 2020
  156. Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications
  157. Special Issue on IC3PE 2018/2019 Conference
  158. Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production
  159. Advancing biodiesel production from microalgae Spirulina sp. by a simultaneous extraction–transesterification process using palm oil as a co-solvent of methanol
  160. Topical Issue on Applications of Mathematics in Chemistry
  161. Omega and the related counting polynomials of some chemical structures
  162. M-polynomial and topological indices of zigzag edge coronoid fused by starphene
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 19.12.2025 from https://www.degruyterbrill.com/document/doi/10.1515/chem-2020-0068/html
Scroll to top button