Recent Advances in the Synthesis and Luminescence Properties of Metal Complexes

A special issue of Inorganics (ISSN 2304-6740). This special issue belongs to the section "Coordination Chemistry".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 19364

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A. V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia
Interests: pyridyl phosphines; organophosphorus chemistry; Group 11 metal-based coordination complexes; coordination polymers; photoluminescence; stimuli-responsive luminescence; thermally activated delayed fluorescence
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Dear Colleagues,

Over the last decade, luminescent metal complexes have been extensively studied all over the world because of their real and potential applications in a diverse variety of high-tech areas. Nowadays, these compounds find wide applications as emitters for organic light-emitting diode (OLED) and light-emitting electrochemical cell (LEEC) devices, as well as optical sensors and probes, bioimaging agents, photocatalysts, and “smart” materials, etc. For this reason, intensive research is now being carried out for stable and low-cost metal complexes that exhibit effective room temperature phosphorescence and thermally activated delayed florescence (TADF). Such complexes are now considered as very promising emitters for energy-efficient OLEDs of the second (PhOLEDs) and third generation (TADF OLEDs), respectively, featuring 100% internal quantum efficiency. Another actively growing area is the design of metal complexes, the emission of which has a reversible response to external physical (temperature, pressure, mechanical stress) or chemical stimuli. Such compounds are crucially important for the creation of highly sensitive sensors, and “smart” materials that can reversibly change their optical properties under external physical/chemical actions.

In this Special Issue, we wish to cover the recent advances in the design, synthesis and investigation of metal complexes and coordination polymers exhibiting photo-, electro- or/and triboluminescence.

Dr. Alexander Artem’ev
Guest Editor

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Keywords

  • coordination metal complexes
  • coordination polymers
  • synthesis
  • room temperature phosphorescence
  • thermally activated delayed fluorescence
  • stimuli-responsive luminescence
  • electroluminescence

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Published Papers (9 papers)

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Research

16 pages, 4655 KiB  
Article
Photophysical Properties of Eu3+ β-Diketonates with Extended π-Conjugation in the Aromatic Moiety
by Vladislav M. Korshunov, Alisia V. Tsorieva, Victoria E. Gontcharenko, Sergey R. Zanizdra, Mikhail T. Metlin, Trofim A. Polikovskiy and Ilya V. Taydakov
Inorganics 2023, 11(1), 15; https://doi.org/10.3390/inorganics11010015 - 28 Dec 2022
Cited by 7 | Viewed by 2003
Abstract
The influence of the degree of π-conjugation in biaroylmethane ligands upon Eu3+ luminescence efficiency in corresponding neutral tris-complexes was investigated in depth. The data obtained by both steady-state and time-resolved luminescence measurements gave an inside into electronic energy transfer mechanisms in the [...] Read more.
The influence of the degree of π-conjugation in biaroylmethane ligands upon Eu3+ luminescence efficiency in corresponding neutral tris-complexes was investigated in depth. The data obtained by both steady-state and time-resolved luminescence measurements gave an inside into electronic energy transfer mechanisms in the abovementioned complexes. It was shown that extension of the π-system in the naphthalene moiety in comparison to the phenyl one lead to a substantial decrease of both the S1 and T1 energy of the corresponding symmetrical β-diketones, which, in turn, led to a decrease of the total quantum yield of respective Eu3+ complexes. The obtained results are of interest for the rational design of highly luminescent complexes with NIR-emitting lanthanides, as the resonant levels energies are low and can hardly be sensitized by common ligands. Full article
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12 pages, 4959 KiB  
Article
Manganese(II) Bromide Compound with Diprotonated 1-Hydroxy-2-(pyridin-2-yl)-4,5,6,7-tetrahydrobenzimidazole: Dual Emission and the Effect of Proton Transfers
by Alexey S. Berezin, Boris Selivanov, Andrey Danilenko, Aleksandr Sukhikh and Andrey Komarovskikh
Inorganics 2022, 10(12), 245; https://doi.org/10.3390/inorganics10120245 - 6 Dec 2022
Cited by 8 | Viewed by 1966
Abstract
An organic–inorganic cation–anion manganese(II) tetrabromide compound with diprotonated 1-hydroxy-2-(pyridin-2-yl)-4,5,6,7-tetrahydrobenzimidazole, [H3L][MnBr4][H2O], has been synthesized and investigated. The compound has a few possible pathways for proton transfers, which play an important role in the observed luminescence, optical, and magnetic [...] Read more.
An organic–inorganic cation–anion manganese(II) tetrabromide compound with diprotonated 1-hydroxy-2-(pyridin-2-yl)-4,5,6,7-tetrahydrobenzimidazole, [H3L][MnBr4][H2O], has been synthesized and investigated. The compound has a few possible pathways for proton transfers, which play an important role in the observed luminescence, optical, and magnetic properties. The proton transfers result in the appearance of two-band luminescence. One band is caused by the Mn(II) d-d transitions. The other band is caused by the transition from the triplet state of organic cation and the d-d transition of manganese(II) coupled through {[H3L]}-{[MnBr4]}-{[H2O]} vibrations. The optical absorption spectra of [H3L][MnBr4][H2O] indicate the presence of two direct and one indirect band transitions. The reason for the two-band luminescence and complex optical absorption in [H3L][MnBr4][H2O] were additionally considered using the DFT calculations. Full article
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14 pages, 2111 KiB  
Article
Composites Based on Polylactide Doped with Amorphous Europium(III) Complex as Perspective Thermosensitive Luminescent Materials
by Andrey A. Knyazev, Aleksandr S. Krupin and Yuriy G. Galyametdinov
Inorganics 2022, 10(12), 232; https://doi.org/10.3390/inorganics10120232 - 30 Nov 2022
Cited by 2 | Viewed by 1787
Abstract
This work reports fabrication of polylactide (PLA) films doped with various additives of an amorphous Eu(III) complex. We study the temperature behavior of the luminescence intensity and lifetime of the PLA-Eu(III) composites in the range of 298–353 K and investigate the mechanism of [...] Read more.
This work reports fabrication of polylactide (PLA) films doped with various additives of an amorphous Eu(III) complex. We study the temperature behavior of the luminescence intensity and lifetime of the PLA-Eu(III) composites in the range of 298–353 K and investigate the mechanism of luminescence temperature quenching. The peak relative sensitivity of the films reaches 20.1 %×K−1 and exceeds the respective characteristics of all known lanthanide-containing thermosensors designed for the range of physiological temperatures. The produced films can be potential novel materials for luminescent thermosensors. Full article
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13 pages, 4628 KiB  
Article
Stabilization of {Ag20(StBu)10} and {Ag19(StBu)10} Toroidal Complexes in DMSO: HPLC-ICP-AES, PL, and Structural Studies
by Victoria V. Volchek, Alexey S. Berezin, Maxim N. Sokolov and Pavel A. Abramov
Inorganics 2022, 10(12), 225; https://doi.org/10.3390/inorganics10120225 - 26 Nov 2022
Cited by 1 | Viewed by 1504
Abstract
The presence of DMSO provides a unique ability to stabilize silver toroidal complexes in the direct reaction between AgStBu and AgNO3 at 80 °C. Slow cooling results in large crystals of [NO3@Ag19.2(StBu)10(DMSO) [...] Read more.
The presence of DMSO provides a unique ability to stabilize silver toroidal complexes in the direct reaction between AgStBu and AgNO3 at 80 °C. Slow cooling results in large crystals of [NO3@Ag19.2(StBu)10(DMSO)5.2(NO3)8.2]·3DMSO (1), which were isolated and characterized by single crystal X-ray diffraction (SCXRD) analysis. The crystal structure contains both {Ag20(StBu)10} and {Ag19(StBu)10} clusters. The solution of these material in DMSO was studied with HPLC techniques, which demonstrated the presence of both complexes in solution. The use of [SiW12O40]4– as counter anion gives crystals of a double complex salt [Ag17.8(NO3)3.8(StBu)10][SiW12O40]·30DMSO (2) under the same conditions. Temperature-dependent photoluminescence (PL) was studied. Full article
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12 pages, 2583 KiB  
Article
Aurophilic Interactions of Dimeric Bisphosphine Gold(I) Complexes Pre-Organized by the Structure of the 1,5-Diaza-3,7-Diphosphacyclooctanes
by Irina R. Dayanova, Adelina I. Fayezova, Igor D. Strelnik, Igor A. Litvinov, Daut R. Islamov, Ilya E. Kolesnikov, Tatiana P. Gerasimova, Elvira I. Musina and Andrey A. Karasik
Inorganics 2022, 10(12), 224; https://doi.org/10.3390/inorganics10120224 - 25 Nov 2022
Cited by 4 | Viewed by 1508
Abstract
The dimeric gold(I) chloride and gold(I) iodide complexes ([L2Au]Cl2 and L2AuI2) on the scaffold of the cyclic bisphosphine, namely 1,5-diaza-3,7-diphosphacyclooctane containing α-phenylbenzyl (benzhydryl) substituents at the nitrogen atoms, were synthesized. The obtained complexes were isolated as [...] Read more.
The dimeric gold(I) chloride and gold(I) iodide complexes ([L2Au]Cl2 and L2AuI2) on the scaffold of the cyclic bisphosphine, namely 1,5-diaza-3,7-diphosphacyclooctane containing α-phenylbenzyl (benzhydryl) substituents at the nitrogen atoms, were synthesized. The obtained complexes were isolated as white crystalline powders. The single crystal XRD of the obtained complexes revealed the strong aurophilic interactions between two gold(I) atoms with the AuAu distance values of 2.9977(6) and 3.1680(5) Å. The comparison of the gold complexes, based on the N,N-diaryl- and N,N-dibenzhydryl substituted 1,5-diaza-3,7-diphosphacyclooctanes, allowed to reveal the strong impact of the initial heterocycle conformation on the realization of the aurophilic interactions, where the geometry of N,N-dibenzhydryl substituted 1,5-diaza-3,7-diphosphacyclooctane, is pre-organized for the intramolecular aurophilic interactions of the complexes. The obtained complexes exhibit a bluish-green phosphorescence (λem 505 (-Cl) and 530(-I)) in the solid state at room temperature, originated by the metal-halide centered transitions, which was confirmed by the TDDFT calculations. It was found that the aurophilic interactions are realized in the ground and in the triplet excited states of the complexes. The slighter change of the geometry of the N,N-dibenzhydryl substituted gold(I) iodide complexes, under the transition from the ground state to the excited state, in comparison with their N,N-diaryl substituted analogues, results in the reduced values of the Stokes shift of luminescence (ca. 150 nm vs. 175 nm). Full article
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16 pages, 3694 KiB  
Article
Synthesis, Structure and Photoluminescence Properties of Cd and Cd-Ln Pentafluorobenzoates with 2,2′:6′,2′-Terpyridine Derivatives
by Maxim A. Shmelev, Julia K. Voronina, Maxim A. Evtyukhin, Fedor M. Dolgushin, Evgenia A. Varaksina, Ilya V. Taydakov, Aleksey A. Sidorov, Igor L. Eremenko and Mikhail A. Kiskin
Inorganics 2022, 10(11), 194; https://doi.org/10.3390/inorganics10110194 - 1 Nov 2022
Cited by 11 | Viewed by 2272
Abstract
Six new complexes [Cd(tpy)(pfb)2] (1, tpy = 2,2′:6′,2″-terpyridine), [Ln2Cd2(tpy)2(pfb)10] (Ln = Eu (2Eu), Tb (2Tb)), [Ln2Cd2(tbtpy)2(pfb)10]·2MeCN (Ln = Eu (3Eu [...] Read more.
Six new complexes [Cd(tpy)(pfb)2] (1, tpy = 2,2′:6′,2″-terpyridine), [Ln2Cd2(tpy)2(pfb)10] (Ln = Eu (2Eu), Tb (2Tb)), [Ln2Cd2(tbtpy)2(pfb)10]·2MeCN (Ln = Eu (3Eu), Tb (3Tb), tbtpy = 4,4′,4″-tri-tert-butyl-2,2′:6′,2″-terpyridine), [Eu2Cd2(tppz)(pfb)10]n (4, tppz = 2,3,5,6-tetra-(pyridin-2-yl)pyrazine) based on pentafluorobenzoic acid (Hpfb) have been prepared and investigated. The effect of tridentate ligands on geometry heterometallic scaffolds synthesized complexes is discussed. The supramolecular crystal structures of the new compounds are stabilized by π-π, C-F···π, C-H···O, C-H...F, F….F interactions. Non-covalent interactions have been studied using Hirschfeld surface analysis. The obtained compounds were characterized by single-crystal and powder X-ray diffraction, luminescence spectroscopy, IR spectroscopy, CHN analysis. Complexes 2Ln and 3Ln exhibit metal-centered photoluminescence, but the presence of ligand luminescence bands indicates incomplete energy transfer from the d-block to the lanthanide ion. Full article
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13 pages, 2410 KiB  
Article
Aliphatic-Bridged Early Lanthanide Metal–Organic Frameworks: Topological Polymorphism and Excitation-Dependent Luminescence
by Pavel A. Demakov, Alexey A. Ryadun and Vladimir P. Fedin
Inorganics 2022, 10(10), 163; https://doi.org/10.3390/inorganics10100163 - 1 Oct 2022
Cited by 8 | Viewed by 2123
Abstract
Six new three-dimensional metal–organic frameworks based on early lanthanide(III) cations and trans-1,4-cyclohexanedicarboxylic acid (H2chdc) were obtained. Their crystal structures were determined by single-crystal X-ray diffraction analysis. The structure of [La2(H2O)4(chdc)3]·2DMF·H2O [...] Read more.
Six new three-dimensional metal–organic frameworks based on early lanthanide(III) cations and trans-1,4-cyclohexanedicarboxylic acid (H2chdc) were obtained. Their crystal structures were determined by single-crystal X-ray diffraction analysis. The structure of [La2(H2O)4(chdc)3]·2DMF·H2O (1; DMF = N,N-dimethylformamide) contains one-dimensional infinite La(III)-carboxylate chains interconnected by cyclohexane moieties to form a highly porous polymeric lattice with 30% solvent accessible volume. Compounds [Ln2(phen)2(chdc)3]·0.75DMF (2Ln; Ln3+ = Ce3+, Pr3+, Nd3+ and Sm3+; phen = 1,10-phenanthroline) are based on binuclear carboxylate building blocks, which are decorated by chelate phenanthroline ligands and interconnected by cyclohexane moieties to form more dense isostructural coordination frameworks with primitive cubic pcu topology. Compound [Nd2(phen)2(chdc)3]·2DMF·0.67H2O (3) is based on secondary building units similar to 2Ln and contains a coordination lattice isomeric to 2Ln with a rare hexagonal helical snz topology. Thermal stability and luminescent properties were investigated. For 2Sm, a strong and nonmonotonous dependence of the luminescence color on the variation of excitation wavelength was revealed, changing its emission from pinkish red at λex = 340 nm to white at λex = 400 nm, and then to yellow at lower excitation energies. Such nonlinear behavior was rationalized in terms of the contribution of several different luminescence mechanisms. Thus, 2Sm is a rather rare example of a highly tunable monometallic lanthanide-based luminophore with possible applications in light-emitting devices and optical data processing. Full article
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10 pages, 2022 KiB  
Article
Luminescent Zn Halide Complexes with 2-(2-Aminophenyl)benzothiazole Derivatives
by Taisiya S. Sukhikh, Dmitry S. Kolybalov, Ekaterina K. Pylova and Sergey N. Konchenko
Inorganics 2022, 10(9), 138; https://doi.org/10.3390/inorganics10090138 - 15 Sep 2022
Cited by 5 | Viewed by 1851
Abstract
We report a comparative study of coordination behaviour of 2-(2-aminophenyl)benzothiazole (NH2-pbt) and its phosphorus-containing derivative, α-aminophosphine oxide (PCNH-pbt), towards zinc halides. The corresponding coordination compounds [Zn(L)2Hal2] (L = PCNH-pbt, Hal = [...] Read more.
We report a comparative study of coordination behaviour of 2-(2-aminophenyl)benzothiazole (NH2-pbt) and its phosphorus-containing derivative, α-aminophosphine oxide (PCNH-pbt), towards zinc halides. The corresponding coordination compounds [Zn(L)2Hal2] (L = PCNH-pbt, Hal = Cl, 1 and Hal = Br, 2) and [Zn(L’)Hal2] (L’ = NH2-pbt, Hal = Cl, 3 and Hal = Br, 4) were obtained as single phases. As evidenced by single-crystal X-ray diffraction analysis, L’ ligand coordinates to Zn in a chelate manner via two N atoms. Despite a similar coordination mode in complexes 3 and 4, the spatial geometry of the ligand differs notably, which implies a relatively high flexibility of NH2-pbt. The L ligand exhibits another coordination mode, binding with Zn only via the oxygen of the P=O group. The differences in the structures of NH2-pbt, 3 and 4, and their counterparts, PCNH-pbt, 1 and 2, induce differences in their solid-state photoluminescence properties. The former group of the compounds exhibits conventional single-band emission, while the latter group reveals two bands. The minor band at 450 nm is ascribed to a radiative transition for the regular amine species, while the major band at 520–550 nm can be associated either with the proton-transferred imine species (ESIPT mechanism) or with a charge transfer state (TICT) with a different geometry. Full article
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17 pages, 8959 KiB  
Article
New Carboxylate Anionic Sm-MOF: Synthesis, Structure and Effect of the Isomorphic Substitution of Sm3+ with Gd3+ and Tb3+ Ions on the Luminescent Properties
by Anna A. Ivanova, Victoria E. Gontcharenko, Alexey M. Lunev, Anastasia V. Sidoruk, Ilya A. Arkhipov, Ilya V. Taydakov and Yuriy A. Belousov
Inorganics 2022, 10(8), 104; https://doi.org/10.3390/inorganics10080104 - 25 Jul 2022
Cited by 15 | Viewed by 3352
Abstract
Two new compounds, namely {(NMe2H2)}[Ln(TDA)(HCOO)] 0.5H2O, Ln = Sm3+ (Sm-TDA) and Gd3+ (Gd-TDA), where TDA3− is the anion of 1H-1,2,3-triazole-4,5-dicarboxylic acid (H3TDA), were synthesized by the [...] Read more.
Two new compounds, namely {(NMe2H2)}[Ln(TDA)(HCOO)] 0.5H2O, Ln = Sm3+ (Sm-TDA) and Gd3+ (Gd-TDA), where TDA3− is the anion of 1H-1,2,3-triazole-4,5-dicarboxylic acid (H3TDA), were synthesized by the solvothermal method in a DMF:H2O mixture. According to single-crystal X-ray diffraction data, the compounds are 3d-MOFs with an anionic lattice and dimethylammonium cations occupying part of the cavities. Based on these compounds, two series of mixed-metal complexes, [NMe2H2][SmxLn1-x(TDA)(HCOO)], (x = 0.9 (Sm0.9Ln0.1-TDA), x = 0.8 (Sm0.8-Ln0.2-TDA)…Sm0.02Ln0.98-TDA, Ln = Tb, Gd), were also obtained and characterized by powder XRD. The luminescent properties of the compounds were studied and it was shown that the resulting compounds are two- or three-component emitters with the possibility of fine color tuning by changing the intensities of fluorescence and phosphorescence of the ligand, as well as the luminescence of Sm3+ and Tb3+ f-ions. Full article
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