Publications by authors named "Victor Kravtsov"

The development of organic/inorganic metal halide perovskites has seen unprecedent growth since their first recognition for applications in optoelectronic devices. However, their thermodynamic stability and toxicity remains a challenge considering wide-scale deployment in the future. This spurred an interest in search of perovskite-inspired materials which are expected to retain the advantageous material characteristics of halide perovskites, but with high thermodynamic stability and composed of earth-abundant and low toxicity elements.

View Article and Find Full Text PDF

2-Hydroxybenzaldehyde 4,S-diallylisothiosemicarbazone (HL) was synthesized and characterized by 1H, 13C NMR and FTIR spectroscopies. It exists in solution in two isomeric forms: cis (~25%) and trans (~75%). Six stable complexes were obtained by interaction of HL with copper(II), nickel(II), cobalt(III) and iron(III) salts: [Cu(L)Cl] (1), [Cu(L)NO3] (2), [Cu(3,4-Lut)(L)NO3] (3), [Ni(L)OAc] (4), [Co(L)2]Cl (5), [Fe(L)2]NO3 (6).

View Article and Find Full Text PDF

Reaction of the polypyridyl ligand 2,4,6-tris(2-pyridyl)--triazine (tpt) with mono- and polynuclear Fe(iii) or Mn(ii) precursors, specifically tri- or hexanuclear Fe(iii) pivalates (piv), [MnO(piv)(Hpiv)] and Mn(ii) isobutyrate (ib), in various solvents and under various reaction conditions showcase the ligand's surprising coordination characteristics. The reactions result in mononuclear [Fe(tpt)(tptH)][FeCl]·2(thf)·0.23(HO) (1), [Fe(piv)(tpt)Cl] (2), [Fe(tpt)Cl]·2(HO) (3a), dinuclear [Fe O(tpt)Cl] (3), and heptanuclear [Fe O(piv)(tpt-O)]·A [A = MeCN (4a) or 4(dioxane) (4b)] and [Fe O(piv)(tpt-O)(i-PrO)(i-PrOH)]·0.

View Article and Find Full Text PDF

Interaction of 2-, 3-, 4-carboxyethylpyridines (L1, L2, L3) with fluorosilicic acid results in the corresponding bis(pyridinium) hexafluorosilicates I-III, characterized by elemental analysis, IR, H, F nuclear magnetic resonance (NMR), and mass spectrometry, solubility data, and X-ray crystallography. Crystallographic data: Fdd2, Z = 8, a = 28.610(2) Å, b = 18.

View Article and Find Full Text PDF

Eight mixed-ligand coordination networks, [Cd(2-aba)(NO)(4-bphz)]·n(dmf) (), [Cd(2-aba)(4-bphz)]·0.75n(dmf) (), [Cd(seb)(4-bphz)]·n(HO) (), [Cd(seb)(4-bpmhz)]·n(HO) (), [Cd(hpa)(3-bphz)] (), [Zn(1,3-bdc)(3-bpmhz)]·n(MeOH) (), [Cd(1,3-bdc)(3-bpmhz)] ·0.5n(HO)·0.

View Article and Find Full Text PDF

1,2,4-Triazole is a very important scaffold in medicinal chemistry due to the wide spectrum of biological activities and mainly antifungal activity of 1,2,4-triazole derivatives. The main mechanism of antifungal action of the latter is inhibition of 14-alpha-demethylase enzyme (CYP51). The current study presents synthesis and evaluation of eight triazole derivatives for their antimicrobial activity.

View Article and Find Full Text PDF

Four coordination compounds [Zn (CH COO) (H O) ](TT) [Cd(H O) ](ClO ) (TT) , [Cd(H O) ](BF ) (TT) , [Zn(H O) ](BF ) (TT) (1-4) accommodating the crystallization induced emissive triimidazo[1,2-a:1',2'-c:1'',2''-e][1,3,5]triazine (TT) as a guest in their crystal lattice are isolated and fully photophysically and structurally characterized. Their emission properties are compared with those of afterglow TT and interpreted taking into account the heavy atom effect and crystal packing similarities and differences. In the case of 1, due to the closeness of the TT H-aggregates arrangement with that of the phosphor's pure phase, the observed intensification of the phosphorescent emission at the expense of the prompt one is attributed to the extrinsic heavy atom effect of Zn.

View Article and Find Full Text PDF

On the way to copper(I) iodide coordination polymers with specific luminescent properties, the in situ reduction of Cu(II) in the presence of KI and bidentate N-heteroatomic ligand, either pyrazine (pyz) or 4,4'-bipyridine (bpy), resulted in one two-dimensional and two three-dimensional new coordination networks. Starting from Cu(NO)·3HO in the presence of pyz, successive precipitation of known yellow [(CuI)(pyz)], new orange [CuI(pyz)], and new dark blue {[Cu(pyz)]·I} polymeric solids was observed. Starting from the same salt in the presence of bpy resulted in the successive precipitation of known yellow [(CuI)(bpy)] and new brown {[Cu(NO)(bpy)]·I·(dmf·HO)} coordination polymers.

View Article and Find Full Text PDF

New tetranuclear and octanuclear mixed-valent cobalt(II/III) pivalate clusters, namely, [NaCo(OCCMe)(HOCCMe)(teaH)(N)]·2HO (in two polymorphic modifications, 1 and 1a) and [Co(OCCMe)(teaH)(N)](MeCCO)·MeCN·HO (2) have been synthesized by ultrasonic treatment of a dinuclear cobalt(II) pivalate precursor with sodium azide and triethanolamine (teaH) ligand in acetonitrile. The use of Dy(NO)·6HO in a similar reaction led to the precipitation of a tetranuclear [NaCo(OCCMe)(teaH)(N)(NO)(HO)]·HO (3) cluster and a heterometallic hexanuclear [CoDy(OH)(OCCMe)(teaH)(HO)](NO)·HO (4) cluster. Single-crystal X-ray analysis showed that 1 (1a) and 3 consist of a tetranuclear pivalate/teaH mixed-ligand cluster [CoCo(OCCMe)(teaH)(N)] decorated with sodium pivalates [Na(OCCMe)(HOCCMe)] (1 or 1a) or sodium nitrates [Na(NO)] (3) to form a square-pyramidal assembly.

View Article and Find Full Text PDF

A family of wheel-shaped charge-neutral heterometallic {FeLn}- and {FeM}-type coordination clusters demonstrates the intricate interplay of solvent effects and structure-directing roles of semiflexible bridging ligands. The {FeLn}-type compounds [FeLn(OCCMe)(N)(Htea)]·2(EtOH), Ln = Dy (1a), Er (1b), Ho (1c); [FeTb(OCCMe)(N)(Htea)] (1d); [FeLn(OCCMe)(N)(Htea)]·2(CHCl), Ln = Dy (2a), Er (2b); [FeLn(OCCMe)(N)(Htea)]·2(EtOH)·2(CHCl), Ln = Dy (3a), Er (3b) and the {FeM}-type compounds [FeM(OCCHMe)(Htea)(tea)(N)]·n(solvent), M = Dy (4, 4a), Gd (5), Tb (6), Ho (7), Sm (8), Eu (9), and Y (10) form in ca. 20-40% yields in direct reaction of trinuclear Fe pivalate or isobutyrate clusters, lanthanide/yttrium nitrates, and bridging triethanolamine (Htea) and azide ligands in different solvents: EtOH for the smaller {FeLn} wheels and MeOH/MeCN or MeOH/EtOH for the larger {FeM} wheels.

View Article and Find Full Text PDF

A series of 2-piperazin-1-yl-quinazolines were synthesized and evaluated for their antiaggregative activity. The synthesized small molecule compounds have potently inhibited platelet aggregation in vitro and blocked FITC-Fg binding to αIIbβ3 integrin in a suspension of washed human platelets. The key αIIbβ3 protein-ligand interactions were determined in docking experiments and some correlations have been observed between values of the affinity and docking scores.

View Article and Find Full Text PDF

A series of new octanuclear propeller-like aminoalcohol-supported Fe(III) oxocarboxylate coordination clusters, [Fe8O3(O2CCHMe2)9(tea)(teaH)3]·MeCN·2(H2O) (1), [Fe8O3(O2CCHMe2)6(N3)3(tea)(teaH)3] (2), [Fe8O3(O2CCMe3)6(N3)3(tea)(teaH)3]·0.5(EtOH) (3), and [Fe8O3(O2CCHMe2)6(N3)3(mdea)3(MeO)3] (4) (where teaH3 = triethanolamine; mdeaH2 = N-methyldiethanolamine) has been isolated and magnetochemically analyzed combining the programs wxJFinder and CONDON in an approach to avoid overparameterization issues that are common to larger spin polytopes. Dominant antiferromagnetic exchange interactions exist in all clusters along the edges of the propellers, while moderate ferromagnetic interactions are found along the propeller axes in their {Fe8O3} metallic cores.

View Article and Find Full Text PDF

Bulk crystals of Cu(2)ZnSiTe(4) (CZSiTe) have been prepared by modified Bridgman method and have been investigated by single crystal X-ray method, Energy Dispersive X-Ray analysis and Raman scattering techniques. The structural studies revealed that the CZSiTe compounds crystallizes in the tetragonal space group I4¯2m, with a = b = 5.9612(1) Å and c = 11.

View Article and Find Full Text PDF

Five oxonium tetrahalogenaurate(III) (Hal = Cl, Br) benzo-crown ether (BCE) complexes are prepared and reported. The new compounds are [(H3O)(B18C6)(0.58)(4'-Cl-B18C6)0.

View Article and Find Full Text PDF

A series of novel RGD mimetics containing phthalimidine fragment was designed and synthesized. Their antiaggregative activity determined by Born's method was shown to be due to inhibition of fibrinogen binding to αIIbβ₃. Molecular docking of RGD mimetics to αIIbβ₃ receptor showed the key interactions in this complex, and also some correlations have been observed between values of biological activity and docking scores.

View Article and Find Full Text PDF

A straightforward approach to heterometallic Mn-Fe cluster-based coordination polymers is presented. By employing a mixed-valent μ(3)-oxo trinuclear manganese(II/III) pivalate cluster, isolated as [Mn(II)Mn(III)(2)O(O(2)CCMe(3))(6)(hmta)(3)]·(solvent) (hmta = hexamethylenetetramine; solvent = n-propanol (1), toluene (2)) in the reaction with a μ(3)-oxo trinuclear iron(III) pivalate cluster compound, [Fe(3)O(O(2)CCMe(3))(6)(H(2)O)(3)]O(2)CCMe(3)·2Me(3)CCO(2)H, three new heterometallic {Mn(II)Fe(III)(2)} cluster-based coordination polymers were obtained: the one-dimensional polymer chain compounds {[MnFe(2)O(O(2)CCMe(3))(6)(hmta)(2)]·0.5MeCN}(n) (3) and {[MnFe(2)O(O(2)CCMe(3))(6)(hmta)(2)]·Me(3)CCO(2)H·(n-hexane)}(n) (4) and the two-dimensional layer compound {[MnFe(2)O(O(2)CCMe(3))(6)(hmta)(1.

View Article and Find Full Text PDF

A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g.

View Article and Find Full Text PDF

Three isostructural cyanido-bridged heptanuclear complexes, [{Cu(II)(saldmen)(H₂O)}₆{M(III)(CN)₆}]-(ClO₄)₃·8H₂O (M= Fe(III) 2; Co(III), 3; Cr(III) 4), have been obtained by reacting the dinuclear copper(II) complex, [Cu₂(saldmen)₂(μ-H₂O)(H₂O)₂](ClO₄)₂·2H₂O 1, with K₃[Co(CN)₆], K₄[Fe(CN)₆], and K₃[Cr(CN)₆], respectively (Hsaldmen is the Schiff base resulting from the condensation of salicylaldehyde with N,N-dimethylethylenediamine). A unique octameric water cluster, with bicyclo[2,2,2]octane-like structure, is sandwiched between the heptanuclear cations in 2, 3 and 4. The cryomagnetic investigations of compounds 2 and 4 reveal ferromagnetic couplings of the central Fe(III) or Cr(III) ions with the Cu(II) ions (J(CuFe) = +0.

View Article and Find Full Text PDF

The bridging of hexanuclear mixed-valent carboxylate coordination clusters of the type [Mn(6)O(2)(O(2)CR)(10)] (R = CMe(3); CHMe(2)) featuring a {Mn(II)(4)Mn(III)(2)(mu(4)-O)(2)} core by geometrically rigid as well as flexible spacer ligands such as pyrazine (pyz), nicotinamide (na), or 1,2-bis(4-pyridyl)ethane (bpe) results exclusively in one-dimensional (1D) coordination polymers. The formation of {[Mn(6)O(2)(O(2)CCMe(3))(10)(Me(3)CCO(2)H)(EtOH)(na)] x EtOH x H(2)O}(n) (1), {[Mn(6)O(2)(O(2)CCHMe(2))(10)(pyz)(3)] x H(2)O}(n) (2), and {[Mn(6)O(2)(O(2)CCHMe(2))(10)(Me(2)CHCO(2)H)(EtOH)(bpe)] x Me(2)CHCO(2)H}(n) (3) illustrates a surprising preference of the interlinked {Mn(6)} units toward 1D coordination chains. In the solid-state, the observed chain propagation axes are either colinear (1 and 3) or perpendicular (2), whereby crystal packing is further influenced by solvent molecules.

View Article and Find Full Text PDF

Two zeolite-like metal-organic frameworks (ZMOFs) with lta- and ast- topologies, zeolitic nets that can be interpreted as augmented edge-transitive 8-connected nets, are targeted through directed self-assembly of metal-organic cubes (MOCs) as supermolecular building blocks (SBBs).

View Article and Find Full Text PDF

Herein we detail a novel approach for targeting zeolite-like metal-organic frameworks (ZMOFs) that utilizes metal-organic cubes, which are regarded as double four-membered rings (d4Rs) and are composite building units (BUs) in traditional inorganic zeolites. Accordingly, we outline the successful implementation of this strategy by reporting two ZMOFs with ACO and AST zeolite-like topologies, which were constructed from d4R BUs exclusively held together by hydrogen bonds. Their porosity was evaluated, delineating high hydrogen uptake and exceptional stability for the two hydrogen-bonded materials.

View Article and Find Full Text PDF

Two novel porous zeolitelike metal-organic frameworks (ZMOFs) were constructed via the single metal ion-based molecular building block approach from rigid and directional tetrahedral building units and pyrimidinecarboxylate bridging ligands; their ion exchange and hydrogen sorption properties were evaluated.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Warning

Message: fopen(/var/lib/php/sessions/ci_session1norudb0fo289d7622nccgrlhlr1cs8q): Failed to open stream: No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 177

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_start(): Failed to read session data: user (path: /var/lib/php/sessions)

Filename: Session/Session.php

Line Number: 137

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once