Volume 77, Issue 9

The crystal structures of sildenafil nitrate trihydrate, (HSild)NO 3 ·3H 2 O ( 1 ), and of the complex salt [Zn(HCit) 2 ]⋅(H 2 Sild) 2 ·2EtOH·6H 2 O ( 2 ) (where Sild = sildenafil, (HSild) and (H 2 Sild) are the mono and doubly charged sildenafil captions, and HCit is the triply deprotonated citric acid) have been determined by single-crystal X-ray diffraction. The compounds have been characterized by FTIR spectroscopy and the cations studied by Hirshfeld surfaces calculations. In compound 2 , the Zn atom is octahedrally coordinated by two tridentate citrate anions. Doubly charged (H 2 Sild) 2+ cations, solvate EtOH and water molecules of crystallization fill the voids of the crystal structure.

Three new lead(II) complexes containing the 1,10-phenanthroline ligand, [Pb(phen) 2 (3,5-DNB) 2 ] ( 1 ), [Pb(phen) 2 (3,5-DNB)(NO 3 )] 2 ·H 2 O ( 2 ), and [Pb(phen)(HCOO)(NO 3 )(H 2 O)] n ( 3 ) (phen = 1,10-phenanthroline, 3,5-DNB = 3,5-dinitrobenzoate anion) have been synthesized and characterized by elemental analyses, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyses (TGA), and single-crystal X-ray diffraction. The complexes 1 and 2 are monomeric species, whereas complex 3 is a one-dimensional polymer. In the three complexes, the ligand phen creates a number of π···π stacking interactions and hydrogen bonds, which play an important role in extending complexes 1 – 3 to supramolecular architectures. The Pb(II) ion of complexes 1 and 2 shows hemidirected geometry with noncovalent Pb···O/C tetrel bonds formed which further stabilize the supramolecular structures.

A new fluorescent sensor, N -allyl-4-[(2-(3-methoxysalicylaldimino)ethylamino]-1,8-naphthalimide (HL), for Hg 2+ has been developed where the Schiff base substituent acts as a recognition group. This sensor shows a large Stokes shift of 3535–4042 cm −1 and a general fluorescence quantum yield of 0.05, 249–0.11, 866 in organic solvents of different polarity as expected. It also exhibits highly selective and a sensitive response to Hg 2+ ( Ф Hg+HL / Ф HL  = 2.28) over other metal ions (Na + , K + , Ca 2+ , Mg 2+ , Al 3+ , Pb 2+ , Fe 3+ , Ni 2+ , Zn 2+ , Cu 2+ , Ag + , Co 2+ , Cr 3+ , Mn 2+ and Cd 2+ ) in solution (DMF/Tris-HCl buffer, 1:1, v / v , pH = 7.2). The Hg 2+ -induced fluorescence enhancement at 526 nm is proportional to the concentration of Hg 2+ in the range of 0.5–4.0 µ m with a detection limit of 0.18 µ m . Based on the fluorescence titration and a Job’s plot analysis, the metal-to-ligand ratio of the complex is 2:1 with a binding constant of 1.56 × 10 12   m −1 .

The one-pot reaction of dimethyl N -cyanodithioiminocarbonate, [(MeS) 2 C=N–C≡N] with n -butyltin trichloride, Sn( n -Bu)Cl 3 led to a dinuclear complex [Sn( n -Bu)Cl 2 (OH)(H 2 O)] 2 which co-crystallized with two [(MeS) 2 C=N–C≡N] molecules ( 1 ). The product was investigated by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the triclinic space group P 1 ‾ $P\bar{1}$ with a  = 6.8048(6), b  = 11.0645(9), c  = 12.4240(10) Å, α  = 66.3120(10), β  = 75.6070(10), γ  = 72.2940(10)°, V  = 807.42(12) Å 3 , Z  = 1 and Z ′ = 0.5. In the complex, two aqua- n -butyltin dichloride, [Sn( n -Bu)Cl 2 (H 2 O)] + , moieties are bridged by two hydroxide OH − ions. Two inner O2–H2OB⋯Cl2 hydrogen bonds strengthen the dinuclear component which is connected to its neighbours through a O1–H1O⋯Cl1 hydrogen bond pattern giving rise to a network of infinite chains running parallel to the (100) direction. The dimethyl N -cyanodithioiminocarbonate molecules are linked to these infinite chains through O2–H2OA⋯N1 hydrogen bonding interactions of D type. The [(MeS) 2 C=N–CN] molecules exhibits a minor positional disorder. These hydrogen bonding interactions lead to cyclic patterns generating R 1 1 ( 6 ) ${\text{R}}_{1}^{1}\left(6\right)$ and R 2 2 ( 8 ) ${\text{R}}_{2}^{2}\left(8\right)$ rings. Weak C–H⋯Cl hydrogen bonds also contribute to the stability of the crystal structure.

Sixteen serjanic acid derivatives were synthesized by modification of the A-ring of the triterpenoid skeleta. Fischer indolization of intermediate 2 with the requisite aromatic hydrazines afforded the indolo-triterpenes 8 – 13 . Also, reaction of 2 with hydroxylamine hydrochloride in pyridine provided the desired C-3 oxime 14 , while pyrazine 15 was obtained by condensation of 2 in the presence of ethylenediamine and sulphur in morpholine. Finally, the Claisen-Schmidt condensation of intermediate 2 with corresponding substituted benzaldehydes 16 – 23 , afforded benzylidine ketones 24 – 31 . All compounds were elucidated on the basis of NMR and HR-MS spectroscopic data and evaluated for their in-vitro cytotoxicity to the Brine Shrimp Lethality Assay (BSLA). As a result, the compounds exhibited medium to good cytotoxic potential and this activity was as high as eight times that of serjanic acid ( 1 ) on the tested zoophytes.

The electron density of a 1:2 complex of valinomycin with calcium triflate consisting of 10 substructures and a total of 279 atoms was examined using the invariom formalism. In addition to geometric properties, sites and strengths of hydrogen bonds were identified from bond topological properties and from electron density concentrations mapped onto Hirshfeld surfaces. In contrast to free valinomycin and corresponding complexes with potassium the hydrogen bonds are all intermolecular and evenly distributed over the complex. A series of electrostatic potential (ESP) surfaces show the mutual influence in the ensemble of this high Z′ structure.

Two coordination polymers, [Zn 2 (bipmo) 2 (1,4-nda) 2 ] n ( 1 ), {[Cd(bipmo)(1,4-nda)]·(H 2 O)} n ( 2 ), (bipmo = bis(4-(1 H -imidazol-1-yl)phenyl)methanone, H 2 (1,4-nda) = naphthalene-1,4-dicarboxylic acid), were synthesized under solvothermal conditions. The complexes have been characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 possesses 3D 2-fold interpenetrating nets with the Schläfli symbol {6 5 ·8}. Complex 2 consists a 3D net with the Schläfli symbol {4 4 ·6 10 ·8}. The luminescent properties of complexes 1 and 2 have been investigated.

Hydrophilic single-wall carbon nanohorns (SWNHs) are produced by using the arc-in-water method. These hydrophilic SWNHs are easily formed in clusters with a diameter of ∼30–40 nm. The XRD pattern features a peak at around 26°, which is typical for SWCNHs. There are evidences of C–C, C=C, C–O, C=O and O=C–O – bonding units based on the XPS spectra of hydrophilic SWNHs. The Raman spectra show that the hydrophilic SWNHs have a high number of defects. Furthermore, stretching vibration bands of C–O, C=C, O=C–O – , C–H and O–H units have been observed by FTIR measurements. All these spectroscopic results are consistent with the structural concepts.

In this paper, we present the crystal structure of the novel compound Sm 3 SiO 5 F 3 . Single crystals were obtained using a high-pressure/high-temperature approach. Sm 3 SiO 5 F 3 crystallizes in the triclinic space group P 1 ‾ $\overline{1}$ ( aP 24) with a  = 6.1894(2), b  = 7.1315(2), c  = 7.3997(3) Å, α  = 103.66(1), β  = 98.06(1), γ  = 90.16(1)°, V  = 314.03(2) Å 3 , Z  = 2 at T  = 300 K and, to the best of our knowledge, presents a new structure type. BLBS and CHARDI calculations were used to assign oxidation states to the atoms, thus allowing us to differentiate between fluorine and oxygen atoms within the crystal structure. MAPLE calculations were carried out to support the structure solution. Electron microprobe measurements corroborate the ratio of Sm to Si and unequivocally prove the presence of Si within the compound. Despite various attempts, bulk synthesis of the compound could not be realized.

A Zn(II) coordination polymer, [Zn 3 (4,4′-BMIBP) 3 (SIP) 2 ] n ( 1 ) (4,4′-BMIBP = 4,4′-bis(2-methyl-imidazolyl)biphenyl, H 3 SIP = 5-sulfoisophthalic acid) was hydrothermally synthesized and structurally characterized. Complex 1 has a (3,4)-connected binodal four-fold three-dimensional topology with a point symbol of {4·6 2 ·8 2 ·10} 2 {4·6 2 } 2 {6 4 ·10 2 }. It shows strong fluorescence emission in the solid state and efficient photocatalytic performances to degrade methylene blue (MB) under UV irradiation, the degradation of MB reaching 88% after 50 min.

Two new cationic four-coordinate Cu(I) complexes supported by different chelating N -heterocyclic carbene ligands and the diphosphine ligand bis[2-(diphenylphosphino)phenyl]ether (POP) have been synthesized. The chemical structures of both complexes have been characterized by 1 H NMR, 13 C NMR, 31 P NMR, and mass spectroscopy, and the crystal structure of one complex has been determined by single-crystal X-ray diffraction. Results of theoretical calculations indicate that the lowest energy electronic transitions of these complexes are mainly the metal-to-ligand charge transfer and ligand-to-ligand charge transfer transitions. The complexes in solid state show intense emissions with high photoluminescence quantum yields. The photophysical behavior at 298 and 77K shows that emissions of these complexes at room temperature are thermally activated delayed fluorescence mixed with phosphorescence.

Although bishydroxylamines have been widely used in chemistry, very little has been reported on corresponding chiral representatives. In this paper, we present the synthesis of two chiral binaphthyl-based bishydroxylamines with different substitution patterns at their NOH functions. The key step of the synthesis involves the reduction of the corresponding dinitrone compounds. The molecular structure in the solid state of one of the nitrone precursors is presented.