卷 67, 编号 7 (2018)
- 年: 2018
- 文章: 27
- URL: https://journals.rcsi.science/1066-5285/issue/view/15007
Reviews
Design of molecular switches based on transition metal bis(dicarbollide) complexes
摘要
The paper presents a review of the state of the art and prospects for the development of rotary molecular switches based on transition metal bis(dicarbollide) complexes.
Article
Graphene oxide supported tin dioxide: synthetic approaches and electrochemical characterization as anodes for lithium- and sodium-ion batteries
摘要
The review addresses synthetic approaches to composite materials based on graphene oxide and nano tin dioxide and their electrochemical properties as anodes for lithium- and sodiumion batteries. The introduction of a carbon matrix into the composite material improves the electrochemical characteristics of the anodes. In most methods, the synthesis of graphene oxide–tin dioxide composites is based on the use of tin(II,IV) chlorides as the starting compounds, and the most efficient electrode materials were obtained by the hydrothermal or solvothermal routes. Thermal processing is much more economic than the gas phase deposition protocols but requires heating of a large volume of dilute tin oxide dispersions in an autoclave. Mechanochemistry (ball milling) is also economically unfavorable for the synthesis of composite materials. In addition, large volumes of acidic wastes that should be neutralized and safely discarded are formed when tin chlorides are used. An alternative environmentally friendly technique based on the use of aqueous peroxide solutions can be applied for the production of efficient anode materials based on graphene oxide and tin dioxide. This process does not involve acidic wastes, uses hydrogen peroxide and ethanol as reagents, and accomplishes film deposition (coating) at room temperature. Final thermal treatment is required only for the active material, which minimizes energy expenses and equipment costs.
Spin crossover in homo- and heteroligand iron(II) complexes with tris(pyrazol-1-yl)methane derivatives
摘要
The studies concerning coordination compounds of various salts of iron(II) with tris(pyrazol-1-yl)methane derivatives (HC(pz)3) are discussed. The results of a number of studies on the synthesis and investigation of the homo- and heteroligand iron(II) complexes with tris(3,5- dimethylpyrazol-1-yl)methane (HC(3,5-Me2pz)3) are considered. The study of the temperature dependence μeff (T) showed that the spin crossover (SCO) 1A1↔5T2 observed in a series of the compounds discussed is accompanied by thermochromism (color change pink (purple) ↔ colorless). Specific features of the SCO and their dependence on the outer-sphere anion in the iron(II) complexes are discussed. The data of the recently published work devoted to the synthesis of the iron(II) complexes with three N-substituted HC(pz)3 derivatives (general formula xL, where x = H, CH2C6H5 (Bn) and p-SO3C6H4CH3 (Ts)) are considered.
Influence of non-bridging donor atoms on the value of exchange interaction in binuclear CuII complexes with bis-hydrazones based on 2,6-diformylphenol
摘要
The quantum chemical simulation of exchange interaction according to the broken symmetry approach was performed for a series of binuclear CuII complexes containing the asymmetric exchange moiety based on bis-hydrazones of 2,6-diformylphenol. The calculated values were compared between themselves and with the experimental values of the exchange parameter 2J for the binuclear copper(II) complexes with bis-hydrazones based on 2,6-diformylphenol in order to reveal the influence pattern of the nature of nonbridging donor atoms X (O, N, S, and Se) onto the exchange interaction. The strength of exchange interaction of the antiferromagnetic type depends significantly on the nature of nonbridging donor atoms, increasing in the series of X = O, NH, S, and Se.
Quantum chemical study of formation of CuII–YIII metallamacrocyclic complexes based on glycinehydroximate ligands
摘要
The process of solution-phase formation of the CuII–YIII 15-metallacrown-5 complexes bearing the glycinehydroximate ligands has been for the first time investigated by methods of quantum chemistry. The DFT modeling at the B3LYP/DGDZVP (PCM) level was carried out for mono-, bi-, and tri-nuclear copper(II) complexes and also for heteronuclear CuII–YIII derivatives as the metallamacrocycle precursors. The dependence of relative stability of these complexes on the CuII and YIII coordination surroundings and also on the mutual positions of ligands was found. The structural (variations of interatomic distances and valence angles), electronic (changes in the atomic charges and electron density), and thermodynamical (enthalpies and Gibbs free energies) regularities of 15-metallacrown-5 formation were revealed. The key role of YIII cation was established for the process of formation of the polynuclear metallamacrocyclic compound (15-metallacrown-5).
Ambidentate and redox-properties of 4,7-phenanthroline-5,6-dione in cobalt complexes: a quantum chemical study
摘要
Mono- and dinuclear adducts of cobalt diketonates with tetradentate 4,7-phenanthroline- 5,6-dione were modeled within the framework of DFT UB3LYP*/6-311++G(d,p) approximation. A competitive coordination of the metal ion to different donor centers of the redox-active ligand was studied. Variation of substituents in the diketone moieties allowed one to reveal compounds than can undergo thermally initiated one- and two-step valence tautomeric rearrangements. The calculated energy and magnetic characteristics of the dinuclear complexes give reasons to consider them as potential basis of molecular electronics and spintronics devices.
Role of macrocyclic effect in complex formation of palladium(II) with ligands anchored on a solid support
摘要
The method for grafting dithiacrown ether and its linear analogue to the silica surface using preliminary prepared organosilicon derivative is developed. The importance of the acylation step in the process of grafting is underlined. The acylation is required to prevent sorption of platinum metals complex anions by the anion exchange mechanism, the probability of which increases due to protonation of the spacer in an acidic medium. The interaction of palladium(II) with anchored ligands in hydrochloric acid media was studied in details. The comparative study of two sorbents revealed that the macrocyclic effect plays a negligible role in binding of palladi um(II) ions. Therefore, linear ligands are preferred for the development of sorbents for molecular recognition of platinum metals ions.
Reactions of Pd-PEPPSI complexes with protic acids
摘要
The Pd-PEPPSI complexes widely used to catalyze numerous reactions eliminate the pyridine ligand on treatment with protic acids to give binuclear complexes [Pd(NHC)X2]2 with the Pd–X–Pd (X = Cl, Br, I) bridging bonds. The reaction proceeds with high yields (78–98%) and can be regarded as a preparative approach to binuclear complexes. A prolonged heat treatment of either Pd-PEPPSI complexes or binuclear [Pd(NHC)X2]2 complexes in the presence of strong protic acids results in the Pd–NHC bond cleavage to give azolium salts (proligands) and palladium salts.
Polynuclear NiII and CoII hexafluoroacetylacetonates
摘要
Hydrolysis of [M4(hfac)4(MeO)4(MeOH)4] (М = Сo, Ni and hfac is hexafluoroacetylaceton ate) is a convenient way of obtaining polynuclear complexes [Ni7(hfac)6(OH)8(H2O)6]•2H2O, [Co12(hfac)10(OH)14(H2O)8]•2H2O•2MePh, [Co12(hfac)10(OH)14(H2O)4(Me2CO)4]•3PhMe, and [Co12(hfac)10(OH)14(H2O)6(Me2CO)2]•2H2O•2Me2CO, whose structures were confirmed by X-ray analysis.
Synthesis of water-soluble bis-N,O-chelate nickel(II) complexes based on new ligands – P-pyridyl-containing phospholane oxides
摘要
A series of new N,O-hybrid ligands was synthesized by oxidation of pyridyl-substituted phospholanes. These ligands were employed in the first synthesis of water-soluble mononuclear nickel(II) complexes [NiL2(H2O)2](BF4)2 and [NiL2(MeCN)2](BF4)2. Physicochemical properties and crystalline structures of the synthesized compounds were thoroughly studied.
Synthesis, structure, and properties of Schiff base iodobismuthate and its alteration in DMSO solution
摘要
New hybrid iodobismuthates (C12H18N2)(BiI4)2 (1, C12H18N2 is N,N´-bis(1- methylethylidene)-1,4-benzоdiammonium dication) and (C6H4(NH3)2) [Bi2I8•2DMSO]•4DMSO (2, C6H4(NH3)2 is p-phenylenediammonium dication) were synthesized and their crystal structures were established. Compound 1 crystallizes in the space group P21/n, a = 7.632(4), b = 13.471(6), c = 14.556(5) Å, β = 93.57(4)°; compound 2 crystallizes in the space group P\(\overline 1 \) , a = 9.208(4), b = 12.203(5), c = 13.600(5) Å, α = 110.20(3)°, β = 97.28(4)°, γ = 110.04(4)°. In the crystal structure of compound 1, one-dimensional infinite BiI4– polyanions are linked into a three-dimensional structure by N,N'-bis(1-methylethylidene)- 1,4-benzоdiammonium dications through N–H…I and C–H…I hydrogen bonds. Compound 1 is stable up to 200 °С, optical studies showed that it has a band gap of 2.15 eV. The recrystallization of compound 1 from DMSO is accompanied by the transformation of chain BiI4–anions to binuclear [Bi2I8•2DMSO]2– anions, while the azomethine cation decomposes to form a p-phenylenediammonium dication.
Interface effects and relaxation processes in nanocomposites based on CdSe/ZnS semiconductor quantum dots and porphyrin molecules
摘要
Controllable self-assembly and properties of nanocomposites based on CdSe/ZnS semiconductor quantum dots (QDs) and tetrapyridylporphyrin molecules (H2P) as well as the dynamics of relaxation processes in these systems were studied for solutions and single nanoobjects in the temperature range of 77–295 K. It was proved that the formation of surface states of different nature is crucial to nonradiative relaxation of exciton excitation in QDs. The efficiency of QD→Н2Р energy transfer was shown to be at most 10–15%. Regularities of photoluminescence (PL) quenching for QDs in nanocomposites in solutions of different polarity correlate with the dependences of PL blinking for single QDs. A scheme was proposed of excited states and main relaxation channels of exciton excitation energy in semiconductor QDs and QD–Н2Р nanocomposites.
Cadmium(II) complexes with monoiodo- and dibromodipyrromethenes: synthesis, molecular structure, spectral-luminescent properties, and stability in solutions
摘要
Cadmium(II) chelates with 4-iodo-, 5,5´-, and 4,4´-dibromo-2,2´-dipyrromethenes (HL1, HL2, and HL3, respectively) with the composition of [CdL2] were synthesized. The influence of structural features of their molecules and properties of the medium on the characteristics of absorption and fluorescence spectra, and also on the thermodynamic stability constants in solutions was evaluated. The results of quantum chemical calculations revealed that the additional coordination interactions between the bromine atoms at the α-positions of dipyrromethene ligands and the complexing atom are possible in the molecular structure of α,α´- dibromosubstituted dipyrromethenate [Cd(L2)2] in contrast with β-halogenated analogues [Cd(L1)2] and [Cd(L3)2].
Spectral study of the reactions of dimethyl sulfoxide with the nitrite complexes of Co-porphyrins
摘要
It is revealed by FTIR and electron absorption spectroscopy that the reactions of dimethyl sulfoxide with the nitro complexes of Co-porphyrins both in the solid phase and an inert solvent afford six-coordinate complexes with the general formula (DMSO)Со(Por)(NO2) (Por is meso-tetraphenyl- and meso-tetra-p-tolylporphyrinato dianions). These compounds are stable in the solid state, whereas they partially decompose in an inert solvent to form five- and six-coordinate complexes. The ambident nitrite and dimethyl sulfoxide ligands are coordinated to the metal atom through the N and O atoms, respectively, which was confirmed by the application of isotope-containing compounds 15NO2 and DMSO-d6.
New ruthenocene-based ruthenium pincer complex bearing the C5Me4CF3 ligand
摘要
The first (trifluoromethyl)tetramethylruthenocene-based ruthenium pincer complex RuCl(CO)[{2,5-(Bu2tPCH2)2C5H2}Ru(C5Me4CF3)] was synthesized by cyclometallation of the bisphosphine ligand {1,3-(Bu2tPCH2)2C5H2}Ru(C5Me4CF3) with RuCl2(DMSO)4 in 2-methoxyethanol in the presence of NEt3. The new complex was fully characterized by 1H, 19F, 31P{1H}, 13C{1H} NMR and IR spectroscopy.
Synthesis and structures of CuI,II complexes with a 2,2´-bipyridine derivative bearing a (+)-3-carene moiety
摘要
The complex salt {[CuL2][Cu4I6]•MeCN}n (1) and the compound [Cu4L3I4]•3 MeCN (2) (L is a chiral ligand bearing a natural monoterpene (+)-3-carene moiety) were synthesized. The crystal structures of compounds 1 and 2 were determined by X-ray diffraction. The structure of compound 1 consists of complex cations [CuL2]2+ (N3O2 polyhedron is a trigonal bipyramid) and CuI coordination polymers (CuI4 polyhedron is a tetrahedron) as anions. The experimental magnetic moment μeff at 300 K is 1.90 μB, which is consistent with the X-ray diffraction data and the assumption that compound 1 is mixed-valence. The structure of compound 2 comprises a tetranuclear CuI complex, in which three Cu atoms are coordinated by two N atoms of the ligand L and two I atoms, and the fourth Cu atom is coordinated by four I atoms (coordination polyhedra are distorted tetrahedra). Compounds L and 2 were found to influence the viability of human laryngeal carcinoma cells (Hep2). The IC50 value for complex 2 (13.0±1.7 μM) is substantially smaller than IC50 for compound L (30.5±0.5 μM).
Synthesis, structure, and luminescent properties of lanthanide complexes containing 1,10-phenanthroline and perfluorinated 2-mercaptobenzothiazolate ligands
摘要
Mononuclear terbium and erbium complexes of the composition Ln(mbtF)3phen and the dinuclear complex Tb2(mbtF)4(OH)2(phen)2 (mbtF is 4,5,6,7-tetrafluoro-2-mercaptobenzothiazolate, phen is 1,10-phenanthroline) were synthesized. The structures of the complexes Er(mbtF)3phen and Tb2(mbtF)4(OH)2(phen)2 were determined by X-ray diffraction. In the solid state, the terbium and erbium complexes exhibit intense metal-centered photoluminescence. Based on the complexes Ln(mbtF)3phen, double-layer organic light-emitting diodes (OLEDs) were assembled. These OLEDs exhibit electroplex emission with a band maximum at 630 nm.
Chiral guest in a chiral framework: X-ray diffraction study
摘要
The inclusion compound of zinc lactate terephthalate with R-butan-2-ol, [Zn2(R-BusOH) (bdc)(S-lac)]•(R-BusOH) (BusOH is butan-2-ol, H2bdc is terephthalic acid, S-H2lac is lactic acid), was prepared by soaking crystals of [Zn2(dmf)(bdc)(S-lac)]•DMF in pure R-butan-2-ol. The positions of chiral alcohol molecules in voids of the chiral framework and the host–guest contacts were determined by X-ray diffraction. These data provide an explanation for the origin of chiral discrimination of zinc lactate terephthalate toward the R-isomer of butan-2-ol.
Association of hydrophilic derivatives of chlorophyll a in ethanol–water and ethanol–water–solubilizer systems
摘要
Electronic absorption spectroscopy and fluorescence spectroscopy were used to study conditions for the formation of associates of amphiphilic phorbins and chlorins in an ethanol–water system. The conditions and degree of disaggregation in the presence of solubilizing additives of nonionic surfactants (Tween 80) and biocompatible polymers (polyethylene glycol and polyvinylpyrrolidone) were also investigated. The propensity of the macroheterocycles based on chlorophyll a to association in water-alcoholic solutions decreases on going from covalently bound dimeric structures to monomeric ones, on going from phorbins to chlorins and on accumulating hydrophilic glycol or positively charged alkylammonium fragments in the molecule. Among the considered solubilizers, the nonionic surfactant Tween 80 emerged as the most efficient means for destroying chlorin associates in water–alcohol solutions with a high content of water.
The synthesis and properties of homologous series of surfactants containing the pyrrolidinium head group with hydroxyethyl moiety
摘要
The surface activity, micelle formation, and solubilization ability towards hydrophobic compounds were estimated for the series of new cationic surfactants belonging to the type of 1-alkyl-1-(2-hydroxyethyl)pyrrolidinium bromides. The presence of 2-hydroxyethyl group in these surfactants leads to the twofold increase in their micelle-forming ability as compared to unsubstituted analogs. The critical micelle concentration for the investigated series of pyrrolidinium surfactants is lower at the same hydrophobicity than that for the analogs belonging to the alkylpyridinium, alkylimidazolium, and alkylmorpholinium types. The data acquired for the studied surfactants on their solubilization ability, antimicrobial activity, and hemolytic efficiency indicate their prospective applications to encapsulate hydrophobic biologically active molecules and as the promising bactericidal agents.
Micellar coordination clusters based on nonionic surfactant Triton Х-114: stability, possibilities of modification, and peculiarities of reactions with cyclodextrins
摘要
New micellar coordination clusters (MCCs) were prepared by the introduction of a hydrophobic chelator onto the interface of nonionic surfactant Triton X-114 followed by “crosslinking” of the structures by metal ions. Their resistance to changes in ionic strength, pH of the solution, and temperature was investigated. Regularities in the interaction of MCCs with α-, β-, and γ-cyclodextrins (CD) were revealed. It was shown that the variation of the type and concentration of CD allowed one to control the mechanism of MCC synthesis and to affect their stability. The involvement of molecular modeling (molecular docking) made possible to elucidate the most energetically favorable structures of complexes of CD with components of MCCs.
Synthesis and structural features of new pentacoordinated monofluorosilanes containing C,O-chelate ligands based on 2-amino acid N-methylamides
摘要
Pentacoordinated monofluorosilanes R1SO2NHCHR2C(O)N(Me)CH2SiMe2F containing moieties of N′-methyl-N-(organosulfonyl)-2-amino acid amides of glycine, alanine, and leucine as C,O-chelating ligands were synthesized via the reaction of corresponding disiloxanes with BF3•Et2O. The structures of obtained compounds were investigated by single-crystal X-ray diffraction analysis.
Influence of aging of poly[(trimethylsilyl)prop-1-yne] on the thermodynamics of sorption of light hydrocarbons
摘要
Changes in the properties of the poly[(trimethylsilyl)prop-1-yne] (PTMSP) film deposited on the walls of a quartz capillary under the action of high temperatures were studied by chromatographic methods. The change in the thermodynamic parameters of sorption of light hydrocarbons related to both physical aging of the PTMSP film and, possibly, its chemical destruction was examined.
Quantitative studies of DNA binding with trans complexes of PtII and PdII featuring tetrazolylacetic acids and their derivatives as ligands
摘要
The interaction of calf thymus DNA (CT DNA) with trans-[PtCl2L2] and trans-[PdCl2L2] complexes (L–5-methyl-1H-tetrazol-1-ylacetic acid and its ethyl, butyl, and isobutyl esters; ethyl esters of 2-R-2H-tetrazol-5-ylacetic acids, R = But, CH2CH2OH) have been quantitatively studied by a spectrophotometric method. The binding constants (Kb) of the tetrazolecontaining coordination compounds with CT DNA at pH 7.2 and 298 K are in the range of (3.67–5.93)•105 mol L–1 for the PdII complexes and (7.82–13.30)•105 mol L–1 for and the PtII complexes, respectively. The Kb values, as well as negative values of ΔGb (–(31.7–34.9) kJ mol–1) indicate the effective binding between the studied complexes and CT DNA.
VII International Conference and Scientific School for Young Scientists “Functional Nanomaterials and High-Purity Substances” October 1–5, 2018, Suzdal
Full Articles
Boron chelate complexes: X-ray and UV photoelectron spectra and electronic structure
摘要
Published data on the electronic structure of boron chelates are summarized for the first time. Ultraviolet photoelectron spectra of vapors, X-ray photoelectron spectra of molecular crystals, and results of modeling within the framework of the density functional theory are analyzed. Data on the effect of substituents on the electronic structure of complexes are systematized.
Brief Communications
Electrically conductive composites of collagen and graphene
摘要
New composite materials of collagen with electrical conductivity up to 6.1•10–4 S cm–1 were obtained using colloidal dispersions of polyvinylpyrrolidone-stabilized graphene.