Russian Journal of Coordination Chemistry最新文献

A series of mononuclear complexes [Ln(Py₃PO)₂(NO₃)₃]·1.5Me₂CO (Ln = Sm, Eu, Gd, Tb, Dy) and [Ln(Py₃PO)(TTA)₃] (Ln = Eu, Tb; TTA^‒ is thenoyltrifluoroacetonate ion) based on tris(2-pyridyl)phosphine oxide (Py₃PO) is synthesized and studied. In the synthesized compounds, Py₃PO acts as a N,O-chelating ligand resulting in the formation of coordination polyhedra N₂O₈ and NO₇ of the Ln atom in complexes [Ln(Py₃PO)₂(NO₃)₃]·1.5Me₂CO and [Ln(Py₃PO)(TTA)₃], respectively. The complexes of Sm³⁺, Eu³⁺, Tb³⁺, and Dy³⁺ ions exhibit lanthanide-centered photoluminescence in the solid phase at 300 K. The energy of the T₁ triplet level of Py₃PO is determined to be 21 900 cm^‒1 from the ligand-centered phosphorescence spectrum of the Gd(III) complex at 77 K. Among the complexes with the ({text{NO}}_{3}^{ - }) ions, Py₃PO exhibits the highest sensitizing ability toward Tb³⁺, whereas the ligand environment in the complexes with the TTA^‒ ions most efficiently sensitizes the Eu³⁺ ion luminescence.

Complexes of various metals have a broad scope of applicability as luminescent materials. These compounds are used both as components of displays, batteries, and semiconductors and in the fields of biology and medicine. This review describes complexes containing group 13, 14, and 15 elements in the molecules, which can be considered as promising luminophores. Their photophysical properties and some aspects of physiological activity are presented.

An approach to the synthesis of polydentate ligands in which the NH-pyrazole cycle is connected by the hydrazone group to the azine fragment (pyridine or pyrimidine) is developed. In the reactions with zinc(II) chloride, the synthesized bis(heterocyclic) compounds act as tridentate ligands with the formation of mononuclear complexes [Zn(L)Cl₂] (CIF files CCDC nos. 2352630 (I) and 2352631 (II)). The absolute quantum yield (QY = 12%) and fluorescence lifetime (τ = 2.64 ns) are measured for complex II containing the pyridine cycle as the azine fragment.

The nickel(II) complex Ni(L)Py (I) (L is 1,3-bis(3,5-di-tert-butyl-2-phenolato)-5,5-dimethyl-(4,6-dihydropyrimidin-2-ylidene)) containing the dianionic bonded N-heterocyclic carbene (NHC) bis(phenolate) ligand is synthesized. In the presence of a stronger base (4-dimethylaminopyridine (DMAP)), the exchange reaction occurs with the replacement of pyridine in complex I by the DMAP molecule to form complex Ni(L)(DMAP) (II), the crystal structure of which is determined by XRD. The synthesized compounds are characterized by elemental analysis, mass spectrometry, and NMR spectroscopy. The spectral characteristics of the compounds are studied.

Two Cd/Co complexes, namely, {[Cd(Bcp)(2,2'-Bpy)(H₂O)]·H₂O}_n (I) and {[Co(Bce)(2,2'-Bpy)]}_n (II) (H₂Bcp = 1,2-bis(4-carboxy-phenoxy)ethane, H₂Bce = 1,3-bis(4-carboxy-phenoxy)propane, 2,2'-Bpy = 2,2'-bipyridine), have been synthesized and structurally elucidated by single crystal X-ray diffraction and thermogravimetric analysis (TGA). Both complexes feature 1D zig-zag chains decorated with 2,2'-Bpy, and the whole supramolecular architectures are stabilized by extensive π···π, C–H···π and H-bonding weak interactions. Complex I shows dual fluorescence sensing towards Fe³⁺ and ({text{C}}{{{text{r}}}_{2}}{text{O}}_{7}^{{2 - }}). The fluorescence quenching mechanism was further investigated.

The reactions of cobalt(II) nitrate with 4,7-di(1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole (Tr₂btd) and aromatic dicarboxylic acids (terephthalic (H₂bdc), 2,6-naphthalenedicarboxylic (2,6-H₂ndc), and 2,5‑furandicarboxylic (2,5-H₂fdc) acids) afford metal-organic frameworks [Co(Tr₂btd)(bdc)]_n (I) and {[Co₂(Tr₂btd)(DMF)(2,6-ndc)₂]·DMF}_n (II) with the layered structures and chain metal-organic framework [Co(Tr₂btd)₂(H₂O)(2,5-fdc)]_n (III). Compounds I and III are paramagnetic in a temperature range of 1.77–300 K without exchange interactions between the Co²⁺ cations, and compound II exhibits the antiferromagnetic interaction between the Co²⁺ cations in the binuclear building blocks with the exchange interaction constant J ≈ −100 K. Single crystals of the phase of compound IIIa with the identical composition but different structure are found when taking samples for X-ray diffraction (XRD) analysis. The molecular structures of metal-organic frameworks I, II, III, and IIIa are determined by XRD (CIF files CCDC nos. 2343141 (I), 2343297 (II), 2343296 (III), and 2343140 (IIIa)).

The reaction of 1,3-diketone containing 1-methyl-1H-pyrazol-4-yl and perfluoropropyl fragments with TbCl₃·6H₂O in the presence of NaOH in ethanol is studied. The molecular and crystal structures of the complex are studied by single-crystal X-ray diffraction (XRD). Compound [Tb(L)₃(EtOH)₂] crystallizes in the triclinic crystal system with the space group (Pbar {1}). The geometry of the coordination polyhedron {LnO₈} corresponds to a square antiprism. Intermolecular interactions N…H–O, C–H…O, and C–H…F leading to the formation of supramolecular chains are observed in crystals of the complex. The UV-irradiated complex exhibits green luminescence caused by transitions ⁵D₄ → ⁷F_j (j = 2–6) characteristic of the Tb³⁺ ion. The main photophysical luminescence parameters are determined, and the scheme of energy transfer in the complex is proposed. The synthesized compound can be of interest as an independent luminophore or as the initial substance for the synthesis of heteroligand complexes by the substitution of ethanol molecules in the internal coordination sphere.

The reactions of salts of cluster anions [Re₆Q₈(CN)₆]^4– with the [Ag(CN)₂]^– dicyanoargentate anion in the presence of 1,2-bis(diphenylphosphino)ethane are studied. Two new coordination polymers, [{(Ag(Dppe))₂(µ-Dppe)}₂{Re₆S₈(CN)₆}]·H₂O (I) and [{(Ag(Dppe))₂(µ-Dppe)}₂{Re₆Se₈(CN)₆}]_0.85-[{(Ag(Dppe))(Ag(DppeSe))(µ-Dppe)}₂{Re₆Se₈(CN)₆}]_0.15 (II), are prepared by the solvothermal synthesis. The XRD study of single crystals of the compounds (CIF files CCDC nos. 2341356 (I) and 2341355 (II)) shows their layered structures. The XRD study of crystalline powders of the compounds shows that the synthesis of compound II leads to the formation of two crystalline phases, one of which is isostructural to compound I. The luminescence parameters of the solid-state compounds (quantum yields, emission lifetimes) resemble the parameters of other coordination polymers based on the [Re₆Q₈(CN)₆]^4– ions.

The development of quantum bits (qubits) is crucial for the progress of quantum technologies. Among various approaches, the qubits based on paramagnetic centers have decent advantages, including their diversity and possibilities of regular ordering, for example, within the structure of metal-organic frameworks (MOFs). In the present work a simple and scalable approach to obtain qubit candidates based on stable organic radical 3-carboxy-proxyl and MOF-808 framework has been demonstrated. Investigation of the obtained compounds with different radical amounts using electron paramagnetic resonance (EPR) demonstrates the presence of two fractions of radicals, which is supported by simulations. Sufficiently long phase memory time at room temperature for the radicals adsorbed into MOF (0.39 μs), as well as the observed Rabi nutations, allow considering this material as a platform for qubits design. The developed approach is capable of incorporating various amounts of paramagnetic centers into the MOF structure and can be employed to obtain other spin qubit candidates.

A new redox-active cobalt(III) complex with a catechol dianion and two 4,4'-dimethoxy-2,2'-bipyridine ligands was synthesized. The reduction of the complex with ascorbic acid in an inert atmosphere was studied by NMR spectroscopy in situ. The reaction followed the first-order kinetics with respect to the starting complex, had a rate constant of 1.1 × 10^–3 s^–1, and was accompanied by the release of catechol, which served as a model drug.