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Dispersion control by using a bulky surfactant medium in the LB films for the enhancement of linearly polarized luminescence of Eu complexes

  • Keiichiro Ozawa , Hideyuki Tanaka , Hitomi Ohmagari ORCID logo , Megumi Ishii , Shinya Kimura , Kenta Goto , Shogo Kawaguchi , Masamichi Yamanaka ORCID logo EMAIL logo and Miki Hasegawa ORCID logo EMAIL logo
Published/Copyright: August 21, 2023
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Pure and Applied Chemistry
From the journal Pure and Applied Chemistry Volume 95 Issue 6

Abstract

The ff transition of lanthanide ions such as Eu in the complex appears as unique energy relaxation process as luminescence after the intramolecular energy transfer from the photo-excitation of the ligand with π-electronic system. The Langmuir-Blodgett (LB) film consisting of Eu and amphiphilic naphtoic acids (NaphC15) induced the linearly polarized luminescence (LPL) with a medium, stearic acid (SA), to isolate the luminescence component by the layer structure and to keep the softness at the monolayer depositions on the quartz substrate as reported previously. Here, we used a bulky medium, 3-methyl-4-penthadecyl benzoic acid (MPBA), instead of SA, and found the Eu-NaphC15 in the LB film places more independently resulting in the 4-fold high quantum yields compared with previous system. The structures of LB films of Eu-NaphC15 with MPBA were elucidated by the measurement of synchrotron XRD and XPS. Various electronic spectra were quantitatively observed to discuss the effect molecular aggregation through much/less ππ-interaction of NaphC15 for the intensified LPL in the films.

Keywords: Europium; inorganic chemistry; Langmuir-Blodgett films; linearly polarized luminescence; luminescence; Mary L. Good

Introduction

The Langmuir-Blodgett (LB) technique is a method for accumulating molecular films with periodicity in the out-of-plane direction and aligning the transition dipole moments of the molecules in the films. The monolayer is transferred from the water/air interface to a solid substrate.

Lanthanide (Ln) ions such as europium (Eu), terbium (Tb), neodymium (Nd) are known to show narrow electronic bands originated from the ff transitions [1]. Their ff-emissions are able to enhance through the intramolecular energy transfer in their complexes with the photo-excitation of π-electronic ligand moieties, so called a photo-antenna effect [2, 3]. Organic ligands have advantage to change the characters of molecules even in metal complexes, for example, amphiphilicity to make self-aggregation systems [4], water-solubility to keep the function in bio-friendly systems [5], [6], [7], chirality to induce circularly polarized photo-functions [8], [9], [10], [11]. Here, we focus on the linearly polarized luminescence (LPL) of Eu complexes in the LB films.

Kitchen et al. reported a series of amphiphilic chiral compounds with Ln luminesces, and also succeeded to induce their circularly polarized luminescence (CPL) in the LB films [4, 12, 13]. They provided the new possibilities to use the CPL in the rigid state enhanced through the energy transfer from the chiral ligand. LPL of Ln complexes were observed in the polymer films [14, 15] and LB films [16], [17], [18], [19], [20], but the number of the reports are quite small still now [21]. Heegar et al. predicted that the appearance of LPL of Eu in a polymer system [14] may be interpreted and enhanced by the direction of electronic dipole moment of the energy donor, the π-electronic ligand.

Naphthoic acid derivative with 15C-alkyl group (abbreviated to NaphC15) formed the LB films with stearic acid (SA) as a medium for keeping the softness to transport from water/air interface to the solid substrate [22]. Naphthalene skeleton acts as a suitable energy donor to Eu-luminescence with the absorption band at 317 and 327 nm of NaphC15 in chloroform. Then, the Eu-containing LB film of NaphC15 and SA (abbreviated to the Eu-NaphC15-SA film) luminesces at 579, 593, 612.5, 649 and 698 nm as 5D0 → 7F0, 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, 5D0 → 7F4 and 5D0 → 7F5 transitions, respectively. It takes a layer structure in 49.8 Å periodicity to the out-of-plane in the 10-layer Eu-NaphC15-SA films. From the measurement of LPL, the film clearly showed the luminescence intensity differences by changing the angles of polarizer in front of detectors. The molecular concentration in the films is much higher than that in solution by 109-times, and it was no way to know the ππ-interaction of NaphC15 themselves. If the ππ-interaction of NaphC15 occurs in the in-plane, the energy donor ability decreases due the donor levels of NaphC15 will be to a lower energy than the initial state. The efficient Eu emission needs to design the well-fitting between the energy donor level of the ligand and acceptor of Eu ion.

Here, we controlled to prohibit the ππ-interaction of NaphC15 themselves to keep the energy donor level of photo-antenna moieties in the film by using bulky medium, 3-methyl-4-penthadecyl benzoic acid (MPBA), newly synthesized (Fig. 1). The film formation with layer-structure were clarified by the measurement of a synchrotron X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and polarized optical waveguide spectroscopy. The luminescence spectra, lifetimes and quantum yields were observed to discuss the medium effects in LPLs of the Eu-NaphC15-MPBA films with the comparison to the previous results.

Fig. 1: Schematic representation of LB films of emissive Eu complexes with NaphC15 using different surfactants illustrating as media (SA and MPBA) to enhance the energy transfer efficiency and ff emissions.
Fig. 1:

Schematic representation of LB films of emissive Eu complexes with NaphC15 using different surfactants illustrating as media (SA and MPBA) to enhance the energy transfer efficiency and ff emissions.

Experimental

Synthesis

3-Methyl-4-pentadecylbenzoic acid (MPBA) was synthesized in three steps from commercially available methyl 4-bromo-3-methylbenzoate (1) (Scheme 1, Fig. S1 and ESI). Sonogashira coupling reaction between 1 and 1-pentadecyne afforded alkylated product 2 in moderate yield. Hydrogenation of alkyne of 2 gave 3 in quantitative yield. Alkaline hydrolysis of ester of 3 yielded desired MPBA as a white solid.

Scheme 1: Synthesis of MPBA. (a) 1-pentadecyne, Pd(PPh3)2Cl2, CuI, PPh3, triethylamine, THF, Δ, 50 %; (b) H2, Pd/C, EtOAc, rt, 98 %; (c) KOH, H2O, THF, MeOH, rt, then HCl aq., rt, 93 %.
Scheme 1:

Synthesis of MPBA. (a) 1-pentadecyne, Pd(PPh3)2Cl2, CuI, PPh3, triethylamine, THF, Δ, 50 %; (b) H2, Pd/C, EtOAc, rt, 98 %; (c) KOH, H2O, THF, MeOH, rt, then HCl aq., rt, 93 %.

LB film deposition

The LB film was accumulated using a mixed chloroform solution containing NaphC15 and MPBA in a 1:7 M ratio, as previously reported [23]. The films were accumulated on hydrophobic quartz substrates by vertical deposition at surface pressure of 15, 20 or 25 mN m−1.

Apparatus

XPS measurements were performed on a KRATOS AXIS ULTRA DLD (Shimadzu) equipped with a monochromatic Al–Ka X-ray source (1253.6 eV); the binding energies were calibrated at the Au 4f level (84.0 eV). Synchrotron XRPD patterns were recorded by a large Debye-Scherrer camera installed at a beamline BL02B2 in SPring-8 (JASRI/SPring-8) using an imaging plate as a detector [24]. Powder samples were prepared in capillaries with 0.3 mm radius and observed in an automatically recording system.

Electronic absorption spectra in the solid state and in the solution were obtained using the diffused reflection method with conversion of the y-axis by UV-3100 and UV-3600S (Shimadzu), respectively. Polarized electronic absorption spectra using optical waveguide system was obtained using a modified SIS-5100 attached with a Glan-Taylor polarizer prism (System Instruments Co.) [25]. Linearly polarized luminescence, steady luminescence and excitation spectra were recorded on a Fluorolog 3–22 (Horiba Jobin Yvon). Absolute luminescence quantum yields and luminescence lifetimes were determined using C9920-02 and Quantaurus τ, C11367-12 with pulsed excitation light sources (Hamamatsu Photonics K. K.), respectively.

Results and discussion

The LB film formations and their structures

Figure 2 shows the π–A isotherm of the film of NaphC15-MPBA (a 1:7 mixing ratio), and the film-deposition ratios on the quartz substrate. From the measurement of π–A isotherms composed in various concentration ratios (Fig. S2) of NaphC15 and MPBA, it was determined the 1:7 mixing ratios is suitable for the deposition. The π–A curve of the film without Eu ion shown in Fig. 2a becomes much clearly when Eu ion was added in the water traf. Then, the suitable surface pressure for the film deposition was determined a region of 15–25 mN m−1. From the similar experimental, the suitable surface pressure to deposit the Eu-MPBA film was 20 mN m−1. The film compression-speed was also considered (Fig. S3), and used at 15 mm min−1 in this investigation. When the 10 layers deposition of the LB film with Eu ion, the deposition ratios on the substrate were stable around 60 % at each up/down stroke (Fig. 2b and S4). The deposition type was a Y-type, which takes a face-on connection between two alkylchains or two carboxylate skeleton among neighbor monolayers. It is expected that Eu ions will be coordinate to the carboxylate sites in the film.

Fig. 2: The L and LB film formations. (a) (left) The π–A isotherm of the films of MPBA, NaphC15-MPBA with (solid line)/without (dotted line) Eu ion in water of subphase, and (right) the film-deposition ratios of Eu-NaphC15-MPBA on the quartz substrate at 20 mN m−1.
Fig. 2:

The L and LB film formations. (a) (left) The π–A isotherm of the films of MPBA, NaphC15-MPBA with (solid line)/without (dotted line) Eu ion in water of subphase, and (right) the film-deposition ratios of Eu-NaphC15-MPBA on the quartz substrate at 20 mN m−1.

Synchrotron XRD, XPS and polarized absorption spectra using a waveguide system of the LB film were observed (Fig. 3). From the XRD patterns of the LB film deposited at 20 mN m−1, the layers take a periodicity in 64 Å. The assumed molecular length of the Eu-NaphC15 was calculated as 36 Å, meaning that the components of the monolayer deposition in the Y-type will be slanted, not perpendicular. The number of peaks differ in other LB films deposited at 15 and 25 mN m−1. Especially, the XRD pattern of the film at 15 mN m−1 show additional peaks, indicating that at least two independently periodical layers will formed and will be more bulky than that at 20 mN m−1.

Fig. 3: Molecular arrangements in the LB films. (a) Synchrotron XRD for out-of-plane of the Eu-NaphC15-MPBA LB film deposited at 20 mN m−1. (b) Eu 3d XPS bands of the LB film (red), Eu-MPBA powder (black) and europium nitrate powder (blue). (c) Polarized absorption spectrum of the LB film recorded on waveguide system. D p and D s are the primary and secondary polarized spectrum, respectively. (d) Schematic representation of inter-layer distance (d) between Eu layers and the tilt angles (ω) localized on the π-electronic systems of the LB film.
Fig. 3:

Molecular arrangements in the LB films. (a) Synchrotron XRD for out-of-plane of the Eu-NaphC15-MPBA LB film deposited at 20 mN m−1. (b) Eu 3d XPS bands of the LB film (red), Eu-MPBA powder (black) and europium nitrate powder (blue). (c) Polarized absorption spectrum of the LB film recorded on waveguide system. D p and D s are the primary and secondary polarized spectrum, respectively. (d) Schematic representation of inter-layer distance (d) between Eu layers and the tilt angles (ω) localized on the π-electronic systems of the LB film.

Eu 3d XPS bands of a powder of Eu(NaphC15)3 were observed at 1135.2 and 1165.8 eV as the Eu 3d 5/2 and 3/2 band, respectively, and that of Eu(MPBA)3 at 1133.8 and 1165.0 eV. The corresponding bands slightly shifted to a low energy side and appear at 1133.0 and 1163.9 eV in the Eu-NaphC15-MPBA film. It suggests that Eu ions certainly coordinate to the surfactant molecules after the film formation. Actually, there are no signal of N 1s of nitrate of Eu(NO3)3, after the film formation (Fig. S5). The C 1s band-shape differences for the complexes, LB films and surfactants themselves means the molecular arrangement of organic components in the film surely changed from each crystalline state. It is also supported from the XRD patterns of the powders.

Owing to estimate the averaged tilt angle (ω) of the π-electronic systems in the LB films, polarized absorption spectra were observed (Fig. 3c) from the transition dipole moment localized on the ligand moieties by using a waveguide system (ESI, Section 10). Here, the primary (D p) and secondary (D s) polarized absorption bands are observed with the perpendicular and horizontal light, respectively, by using a polarizer in front of the light source. The absorbances at 315 nm are 0.22 for D p and 1.64 for D s in the Eu-NaphC15-MPBA film resulting to the tilt angle as approximately 26°. The angle of the films with MPBA was smaller than that of the film with SA previously we reported.

Luminescence properties of the LB films

The 1:7 mixed solution of NaphC15 and MPBA in chloroform shows the absorption bands at 310, 290 and 245 nm (Fig. S6) assigned to the ππ transitions of NaphC15 with the comparison of previous report [22]. Their band position and shape keep even in the 10-layer LB films.

Figure 4 shows the luminescence spectra of the Eu-NaphC15-MPBA film and the Eu-MPBA film deposited at 20 mN m−1 (λ ex = 310 nm) with each phosphorescence spectra using gadolinium (Gd) ion. It is useful to know the triplet band position localized on the π-electronic systems in the lanthanide complexes by using Gd ion due to no energy accepter level in the ion and no ff emission band [26].

Fig. 4: Luminescence spectra. (a) Luminescence spectra (λ ex = 310 nm) of the Eu-NaphC15-MPBA LB film (black) at rt and the Gd-NaphC15-MPBA film at 77 K (blue). (b) Solid state-luminescence spectra (λ ex = 290 nm) of MPBA complexes with Eu (solid line) at rt and Gd (dotted line) at 77 K. *: Due to impulities.
Fig. 4:

Luminescence spectra. (a) Luminescence spectra (λ ex = 310 nm) of the Eu-NaphC15-MPBA LB film (black) at rt and the Gd-NaphC15-MPBA film at 77 K (blue). (b) Solid state-luminescence spectra (λ ex = 290 nm) of MPBA complexes with Eu (solid line) at rt and Gd (dotted line) at 77 K. *: Due to impulities.

The luminescence bands of the Eu-NaphC15-MPBA film are observed at 579, 591.5, 614.0, 651.0 and 699.0 nm are assigned to the 5D0 → 7F0, 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, 5D0 → 7F4 and 5D0 → 7F5 transitions, respectively. The excitation bands monitored at 615 nm correspond to the absorption bands. The band position of phosphorescence band of NaphC15 in the Gd-NaphC15-MPBA film is around 500–600 nm. The main band at 507 nm (19 700 cm−1) is suitable to act as an energy donor to Eu, because the accepter level of Eu is around 17 200 cm−1 for 5D0 or 19 000 cm−1 for 5D1 within the permissible differences (ca. 3000 cm−1) for energy transfer. Thus, the ff emission of Eu in the film is induced by the π electronic systems of NaphC15 through the energy transfer. Interestingly the red emission of Eu ion is so strong that it can be seen by our naked eyes. Similar spectra were observed in both films deposited at 15 and 25 mN m−1 (Fig. S7).

Luminescence lifetimes (τ) and total luminescence quantum yields by ligand excitation (φ ff) are summarized in Table 1 with the photophysical parameters calculated by equations in ESI. The τ values are estimated from the decay profiles (Fig. S8). The φ ff of the Eu-NaphC15-MPBA LB film deposited at 20 mN m−1 is three-fold greater than that of previous data using SA instead of MPBA. It may depend on the less ππ interaction between neighbor naphthalene moieties as designed. The φ ff values of other two films deposited at 15 and 25 mN m−1 are comparably small. The luminescence of the solid state MPBA complex with Eu also observed and estimated their photo-physical parameters (φ ff = 0.75 and η EnT = 11.1 %). Interestingly, the luminescence bands of the Eu-MPBA film are also observed at 579.5, 592.0, 615.0, 651.5 and 699.0 nm assigned to the 5D0 → 7F0, 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, 5D0 → 7F4 and 5D0 → 7F5 transitions, respectively, meaning that MPBA also acts as energy donor to the Eu emission. The φ ff value and η EnT of the Eu-MPBA film were 4.6 %, and 17.1 %, respectively, and comparably lower than those of the Eu-NaphC15-MPBA film (14.8 % and 46.2 %, respectively). The phosphorescence band at 435 nm localized on MPBA of the Gd-MPBA film support their energy transfer possibility, but less contribution more than that with NaphC15 systems. Additionally, the η EnT value of Eu-NaphC15-MPBA LB film (20 mN m−1) corresponds to that of Eu-NaphC15-SA LB film. However, the quantum yield of Eu-NaphC15-MPBA LB film (20 mN m−1) drastically increases three folds of that of Eu-NaphC15-SA LB film [22] due to the worthy differences of their K R and K NR. Thus, the steric hindrance of MPBA surely influences the energy relaxation process with luminescence in the LB films compared with that in SA.

Table 1:

Photophysical parameters of Eu complexes in the films and powders.

φ ff τ 1 [ms] (amp.) τ 2 [ms] (amp.) τ 3 [ms] (amp.) τ av [ms] K R [s−1] K NR [s−1] η EnT
Eu-NaphC15/MPBA LB film (15 mN m−1) 4.9 % 0.34 (30 %) 0.68 (70 %) – 0.62 573 1040 13.8 %
Eu-NaphC15/MPBA LB film (20 mN m−1) 14.8 % 0.33 (29 %) 0.62 (71 %) – 0.57 562 1192 46.2 %
Eu-NaphC15/MPBA LB film (25 mN m−1) 6.0 % 0.22 (39 %) 0.56 (61 %) – 0.49 472 1569 26.0 %
Eu-MPBA LB film 4.6 % 0.26 (37 %) 0.61 (63 %) – 0.54 499 1353 17.1 %
Eu-MPBA powder 0.75 % 3.9 × 10−10 (78 %) 0.025 (17 %) 0.29 (5.0 %) 0.24 285 3881 11.1 %
Eu-NaphC15/SA LB film 5.8 % [22] 0.26 (48 %) 0.08 (39 %) 0.56 (13 %) 0.33 490 2500 49.0 %

Other LB films composed with Eu-NaphC15-MPBA at various surface pressure at 15 and 25 mN m−1 also show their luminescence of Eu, but their φ ff values were quite low, 4.9 % and 6.0 %, respectively with the low η EnT of 13.8 % and 26.0 %. It means that the film deposited at 20 mN m−1 is suitable molecular aggregation for the efficient luminescence, actually it also shows the drastic LPL changes compared with others as described later.

Figure 5 shows the LPL spectra of the Eu-NaphC15-MPBA LB films deposited at various surface pressure with the set-up of the measurement. The polarizer in front of the excitation light and a detector are fixed at 0° and mobile from 90 to 0° with 10° each, respectively. Due to the directional behavior of excitation light, each LPL spectrum of the film was corrected by using isotropic sample such as solutions showing no LPL spectra. It worth to note that the LB film deposited at 20 mN m−1 clearly demonstrates the LPL compared with other two LB films. The relative intensity at 620 nm increases with the turning of a polarizer from 90° to 0°. From the structure aspects above described, it was also suggested the surface pressure condition will affect the molecular aggregation in the LB films. For instance, in our previous work it noted that clearly well-ordered molecular sequences have been found to express LPL, which corresponds to an optimum surface pressure [22]. Thus, the 20 mN m−1 is the suitable surface pressure to align the layer structure. Additionally, the contrast of the LPL phenomena in the Eu-NaphC15-MPBA LB film is obvious more than that in the Eu-NaphC15-SA LB film. The φ ff value also indicated the less ππ interaction between neighbor naphthalene moieties in the Eu-NaphC15-MPBA LB film, then the NaphC15 moiety will independently exist and affect for the interpretation of its electronic dipole moment for LPL of Eu emission. No LPL spectrum was observed in the Eu-MPBA LB film (Fig. S9), meaning that LPL phenomena of the Eu-NaphC15-SA LB film is surely enhanced by NaphC15 independently existed.

Fig. 5: Linearly polarized luminescence spectra of the LB films deposited under the surface pressure of 15 (a), 20 (b) and 25 (c) mN m−1. (d) Set-up of two polarizers for the measurement; α 0 and α are the angle of polarizer in front of the excitation light source and the detector, respectively.
Fig. 5:

Linearly polarized luminescence spectra of the LB films deposited under the surface pressure of 15 (a), 20 (b) and 25 (c) mN m−1. (d) Set-up of two polarizers for the measurement; α 0 and α are the angle of polarizer in front of the excitation light source and the detector, respectively.

Conclusions

The LB films have a roughly periodic arrangement of molecules with Ln ions. The method of forming such flexible films at the air–water interface has a positive impact on the environment. With this method, it was able to use very small amounts of lanthanides to develop characteristic optical functions and to find conditions to control these in the in-plane and out-of-plane directions of the membrane. In particular, the method in which the energy donor NaphC15 inhibits its own intermolecular interactions with the bulky surfactant MPBA reflected well the characteristics of molecular self-assembly. The correlation between structure and luminescence was proved by LPL statements. Such a system provides an impetus for new production methods of polarized luminescent materials, and is also expected to be applied to sensors and other applications.

Corresponding authors: Miki Hasegawa, Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 252-5258 Kanagawa, Japan; and Masamichi Yamanaka, Department of Pharmacy and Health Sciences, Faculty of Pharmaceutical Sciences, Meiji Pharmaceutical University, 204-8588 Tokyo, Japan, e-mail: (M. Hasegawa), (M. Yamanaka)
Article note: A special issue of PAC in honor of Dr. Mary L. Good (1931–2019), a leader and pioneer in the field of inorganic chemistry. In addition to a distinguished career in academia, industry, and government.

Funding source: Tokuyama Science Foundation

Funding source: Japan Synchrotron Radiation Research Institute

Award Identifier / Grant number: 2020A1451

Award Identifier / Grant number: 2022B0571

Funding source: Research Institute, Aoyama Gakuin University

Award Identifier / Grant number: Early Eagle

Funding source: Ministry of Education, Culture, Sports, Science and Technology

Award Identifier / Grant number: 17H06374

Award Identifier / Grant number: 20201320

Award Identifier / Grant number: 20211314

Award Identifier / Grant number: 20221164

Award Identifier / Grant number: 20K15041

Award Identifier / Grant number: 23K13561

Funding source: Network Joint Research Center for Materials and Devices

Award Identifier / Grant number: 20201320

Award Identifier / Grant number: 20211314

Award Identifier / Grant number: 20221164

  1. Research funding: This work was supported by JSPS KAKENHI, Japan, for Scientific Research on Innovative Areas “Soft Crystals (Area Number 2903),” under Grant No. 17H06374 (MH); the Grant-in-Aid for Early-Career Scientists, under Grant No. 20K15041 and 23K13561 (HO); Aoyama Gakuin University Research Institute’s “Early Eagle” grant program for promotion of research by early career researchers (HO); the Tokuyama Science Foundation, Japan (HO); and the Cooperative Research Program of “Network Joint Research Center for Materials and Devices,” under Grant Nos. 20201320, 20211314, and 20221164. The synchrotron radiation experiments were performed at the BL02B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (Proposal No. 2020A1451 and 2022B0571).

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Supplementary Material

This article contains supplementary material (https://doi.org/10.1515/pac-2023-0403).

Published Online: 2023-08-21
Published in Print: 2023-06-27

© 2023 IUPAC & De Gruyter

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  1. Frontmatter
  2. In this issue
  3. Editorial
  4. Special issue in honour of Dr. Mary Lowe Good
  5. Special topic papers
  6. Metal ion-assisted supramolecular gelation
  7. Synthesis and optical properties of phosphorus doped ZnO: X-ray absorption, X-ray emission, and X-ray excited optical luminescence studies
  8. A facile preparation of graphene hydrogel-supported bimetallic RuM (M: Co, Ni, Cu) nanoparticles as catalysts in the hydrogen generation from ammonia borane
  9. How to get deeper insights into the optical properties of lanthanide systems: a computational protocol from ligand to complexes
  10. Heuristic algorithms for understanding chemistry via simple quantities
  11. A NiII–WV(CN)8 layer magnet showing metamagnetic behavior
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  13. Dispersion control by using a bulky surfactant medium in the LB films for the enhancement of linearly polarized luminescence of Eu complexes
https://doi.org/10.1515/pac-2023-0403
Keywords for this article
Europium; inorganic chemistry; Langmuir-Blodgett films; linearly polarized luminescence; luminescence; Mary L. Good

Articles in the same Issue

  1. Frontmatter
  2. In this issue
  3. Editorial
  4. Special issue in honour of Dr. Mary Lowe Good
  5. Special topic papers
  6. Metal ion-assisted supramolecular gelation
  7. Synthesis and optical properties of phosphorus doped ZnO: X-ray absorption, X-ray emission, and X-ray excited optical luminescence studies
  8. A facile preparation of graphene hydrogel-supported bimetallic RuM (M: Co, Ni, Cu) nanoparticles as catalysts in the hydrogen generation from ammonia borane
  9. How to get deeper insights into the optical properties of lanthanide systems: a computational protocol from ligand to complexes
  10. Heuristic algorithms for understanding chemistry via simple quantities
  11. A NiII–WV(CN)8 layer magnet showing metamagnetic behavior
  12. Transition metal complexes for electrochromic and electrofluorochromic devices
  13. Dispersion control by using a bulky surfactant medium in the LB films for the enhancement of linearly polarized luminescence of Eu complexes
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