Konstantin A. Brylev

Coordination polymers based on the [{Mo ₆ I ₈ }(CN) ₆ ] ²⁻ cluster exhibit bright photo- and X-ray induced luminescence in the red and near-infrared regions.

First metal–organic coordination polymer based on the [{Mo₆I₈}(CN)₆]²⁻ cluster anion was obtained using the salts Cs_1.3Na_0.7[{Mo₆I₈}(CN)₆]·2H₂O (1) and K[Ag(CN)₂], as well as bis(diphenylphosphino)methane (dppm), as precursors. In contrast to the previously reported coordination polymers based on octahedral cyanide cluster complexes, the 1D polymer [{Ag₂(dppm)₂}{Mo₆I₈}(CN)₆] (2) demonstrated an order of magnitude increase in the cluster-centred photoluminescence quantum yield (Φ_em) in the solid state at 300 K in comparison with the ionic salt 1. Moreover, 2 exhibits bright X-ray-induced emission, which is two orders of magnitude more intense than that of 1 and is characterized by a light yield of 10 800 photons per MeV. Therefore, 2 represents the first effective scintillating compound based on octahedral molybdenum clusters. The polymer has exceptional thermal, photo- and hydrolytic stability and exhibits minimal degradation upon X-ray irradiation, retaining its emission intensity following exposure to the dose of 2.2 × 10⁵ rad. It should be noted that this level of radiation resistance is superb even for inorganic scintillation materials. The high light yield and exceptional stability of the compound enabled us to use it to manufacture scintillation screens for X-ray visualisation. These screens provide a spatial resolution of up to 9 line pairs per mm, representing the first example of a scintillation device based on molybdenum clusters.

Unprecedented Cu^I, Ag^I and Au^I clusters with pronounced metallophilic Au–X (X = Cu, Ag, Au) or Ag–Ag contacts have been assembled using 1,2-bis[bis(pyridin-2-ylmethyl)phosphino]ethane (L), an innovative P,P′(N,N′)₂-ligand. Its interaction with AuCl/KPF₆, AuI or (AuCCPh)_n yields complexes of the type [Au₂L₂]²⁺, [Au₂I₂L₂] and [Au₂(CCPh)₂L]_x (x = 2 or n), respectively. The reaction of L with AgPF₆ affords a [Ag₄L₂]⁴⁺ cluster, while the treatment with AgNO₃ leads to a nine-nuclear [Ag₉L₃(NO₃)₃]⁶⁺ cluster. The latter was transformed into a heterometallic [Au₂Ag₄L₂(NO₃)₂(H₂O)]⁴⁺ cluster by treatment with [Au(tht)Cl]. Sequential reaction of L with Au(I) halides and [Cu(MeCN)₄]PF₆ provides heterometallic [Au₂Cu₄(μ₂-Cl)₂L₂]⁴⁺ and [Au₂Cu₄L₂I₂(MeCN)₄]⁴⁺ ensembles. Most of the title clusters exhibit a charge transfer photoluminescence in the green to orange region with the quantum efficiencies up to an impressive 77%. Surprisingly, the [Au₂Cu₄L₂I₂(MeCN)₄]⁴⁺ cluster shows an abnormal (negative) thermal quenching of the luminescence, which is unprecedented for Au(I) derivatives. The practical utility of the designed clusters was demonstrated by their application as innovative vapor-responsive emission inks for advanced anticounterfeiting.

Tungsten trioxide can be used as a readily available source in the one-step preparation of a variety of cyanide and chalcocyanide mononuclear and cluster complexes of tungsten. In our study of phase formation in the system 6WO₃ + 8Q + 32NaCN (Q = S, Se or Te) in the temperature range of 250–700 °C, we determined which soluble complex compounds are formed, the temperature limits of their existence and the influence of synthesis time on the composition of the products. As the temperature increases, the process begins with the formation of mononuclear and then cluster complexes and ends with the formation of tungsten dichalcogenides: [W(CN)₈]⁴⁻ → [WS₄]²⁻/[WS₃O]²⁻ → [{W₃Q₄}(CN)₉]⁵⁻ (Q = S or Se), [{W₃S₃O}(CN)₉]⁵⁻ → [{W₄Q₄}(CN)₁₂]⁶⁻ (Q = S, Se or Te) → WQ₂ (Q = S or Se). Depending on the synthesis conditions, these complexes can either coexist in a mixture or one of them becomes the main product of the reaction. The obtained trinuclear and tetranuclear cluster complexes were studied by ¹³C, ⁷⁷Se and ¹⁸³W NMR spectroscopy using DFT calculations to assign the spectral signals. The crystal structures of the salts Cs₅Na₃[W(CN)₈]₂·2H₂O (1), Cs_2.8Na_2.2[{W₃S₄}(CN)₉]·2.2H₂O (2), Cs₅[{W₃S₃O}(CN)₉]·2H₂O·0.5CsCl (3) and Cs_3.5Na_1.5[{W₃Se₄}(CN)₉]·6.5H₂O (4) were determined by single-crystal X-ray diffraction analysis. It was also revealed that the quantitative ratio of trinuclear complexes [{W₃S₃O}(CN)₉]⁵⁻ and [{W₃S₄}(CN)₉]⁵⁻ with different cluster core compositions formed in the 6WO₃ + 8S + 32NaCN system at 300 °C depends on the synthesis time. Dynamics of the observed transformation of the initially dominant complex with a heteroleptic cluster core {W₃(μ₃-S)(μ-S)₂μ-O} into the complex with a homoleptic core {W₃(μ₃-S)(μ-S)₃} was studied using ¹³C NMR spectroscopy.

Tetraphosphine-carbene Cu(i), Ag(i) and Au(i) complexes, synthesized via a symmetry-based design strategy, exhibit cyan to yellow TADF with excellent quantum yields (58–89%) and reduced lifetimes.

A supramolecular hybrid organic–inorganic framework is generated by combining a blue fluorescent tetraphenylethylene-based dication and a red-NIR phosphorescent octahedral rhenium cluster tetra-anion.

Blue-emitting anthracene derivatives are associated via hydrogen bonds to a red-emitting [Mo₆I₈(OCOC₂F₅)₆]²⁻ anion leading, once embedded in PMMA, to films whose emission color depends on the irradiation power and time.

This review analyzes literature on polymeric transition metal polychalcogenides of group IV–VII This review systematizes literature data on polymeric polychalcogenides of group IV–VII transition metals (TiS3, VS4, NbSe3, MoSx, ReS4, etc.). It covers the structural characteristics of crystalline compounds and the proposed structural models of amorphous phases. The latest advances in the synthesis of these low-dimensional materials at the nanoscale are presented. Their chemical properties are discussed, in particular, those arising from the presence of the dichalcogenide bonds. It is emphasized that the properties of the S–S (or Se–Se) groups largely determine the distinctive features of polychalcogenides and the unusual phenomena observed in them. In particular, these groups play an important role in the performance of electrode materials in metal-ion batteries, photo- and electrocatalysts for hydrogen evolution reaction, and mercury vapour sorbents based on transition metal polychalcogenides, which is also addressed in this review. The bibliography includes 304 references.

Two-dimensional black phosphorus (BP) has attracted great attention as a perspective material for various applications. The chemical functionalization of BP is an important pathway for the preparation of materials with improved stability and enhanced intrinsic electronic properties. Currently, most of the methods for BP functionalization with organic substrates require either the use of low-stable precursors of highly reactive intermediates or the use of difficult-to-manufacture and flammable BP intercalates. Herein we report a facile route for simultaneous electrochemical exfoliation and methylation of BP. Conducting the cathodic exfoliation of BP in the presence of iodomethane makes it possible to generate highly active methyl radicals, which readily react with the electrode’s surface yielding the functionalized material. The covalent functionalization of BP nanosheets with the P–C bond formation has been proven by various microscopic and spectroscopic methods. The functionalization degree estimated by solid-state ³¹P NMR spectroscopy analysis reached 9.7%.

A series of eight new octahedral rhenium cluster complexes with the general formula trans-[{Re₆Q₈}L₄X₂] (Q = S or Se; L = 1,2-Bis(4-pyridyl)ethylene (bpe) or 1,3-Bis(4-pyridyl)propane (bpp); X = Cl or Br) was synthesized and investigated. While bpe is a ligand with a conjugated aromatic system, bpp represents a molecule of opposite type and has independent aromatic systems of the two pyridine rings. It was shown that this difference in the electronic structure of the ligands has a fundamental effect on the electronic structure, electrochemical and luminescent properties of the corresponding cluster complexes. Specifically, the [{Re₆Q₈}(bpe)₄X₂] complexes in solutions show multiple quasi-reversible electrochemical transitions associated with reduction of the organic ligands. At the same time, the trans-[{Re₆Q₈}(bpp)₄X₂] complexes show multielectron quasi-irreversible reduction processes, which correlate with the mixed character of the lowest unoccupied molecular orbitals of these complexes. All the obtained new compounds exhibit red photoluminescence. The photophysical parameters (emission lifetimes and quantum yields) measured for the bpp complexes exceed those revealed for bpe complexes by more than an order of magnitude.