Search

The coordination diversity of a novel N4-ligand and its sodium complex toward cobalt(ii) ions was studied.

The present work describes an efficient reaction of electrochemical phosphorylation of phenylacetylene controlled by the composition of catalytic nanoparticles based on non-noble-metals. The sought-after products are produced via the simple synthetic protocol based on room temperature, atom-economical reactions, and silica nanoparticles (SNs) loaded by one or two d-metal ions as nanocatalysts. The redox and catalytic properties of SNs can be tuned with a range of parameters, such as compositions of the bimetallic systems, their preparation method, and morphology. Monometallic SNs give phosphorylated acetylene with retention of the triple bond, and bimetallic SNs give a bis-phosphorylation product. This is the first example of acetylene and phosphine oxide C-H/P-H coupling with a regenerable and recyclable catalyst.

A series of D-π-A, D-π-D'-π-A, D-π-A'-π-A nonlinear optical chromophores with vinylene π-electron bridges or bridges with π-deficient/π-excessive heterocyclic moieties along with the corresponding precursors D-vinylene, D-π-D', D'-π-A, D-π-A' and A'-π-A are synthesized and studied both experimentally and computationally. The effect of the heterocycle in the π-electron bridge on the oxidation/reduction potentials and the energy gap (ΔEel ) is investigated in detail. The properties of the D-π-A'(D')-π-A chromophores are shown to correlate with those of building blocks: the oxidation potential is determined by the D-vinylene, and the reduction potential is determined by A'(D')-π-A truncated compounds. The contribution of the acceptor to the oxidation potential of chromophores in comparison with those of the precursors was estimated and analyzed in terms of electronic communication between the end groups. A good correlation between the ΔEel and the chromophores' first hyperpolarizability is revealed.

Redox properties of monoiminoacenaphthenes (MIANs) were studied using various electrochemical techniques. The potential values obtained were used for calculating the electrochemical gap value and corresponding frontier orbital difference energy. The first-peak-potential reduction of the MIANs was performed. As a result of controlled potential electrolysis, two-electron one-proton addition products were obtained. Additionally, the MIANs were exposed to one-electron chemical reduction by sodium and NaBH4. Structures of three new sodium complexes, three products of electrochemical reduction, and one product of the reduction by NaBH4 were studied using single-crystal X-ray diffraction. The MIANs reduced electrochemically by NaBH4 represent salts, in which the protonated MIAN skeleton acts as an anion and Bu4N+ or Na+ as a cation. In the case of sodium complexes, the anion radicals of MIANs are coordinated with sodium cations into tetranuclear complexes. The photophysical and electrochemical properties of all reduced MIAN products, as well as neutral forms, were studied both experimentally and quantum-chemically.

Nowadays, hydrogen has become not only an extremely important chemical product but also a promising clean energy carrier for replacing fossil fuels. Production of molecular H2 through electrochemical hydrogen evolution reactions is crucial for the development of clean-energy technologies. The development of economically viable and efficient H2 production/oxidation catalysts is a key step in the creation of H2-based renewable energy infrastructure. Intrinsic limitations of both natural enzymes and synthetic materials have led researchers to explore enzyme-induced catalysts to realize a high current density at a low overpotential. In recent times, highly active widespread numerous electrocatalysts, both homogeneous or heterogeneous (immobilized on the electrode), such as transition metal complexes, heteroatom- or metal-doped nanocarbons, metal-organic frameworks, and other metal derivatives (calix [4] resorcinols, pectates, etc.), which are, to one extent or another, structural or functional analogs of hydrogenases, have been extensively studied as alternatives for Pt-based catalysts, demonstrating prospects for the development of a “hydrogen economy”. This mini-review generalizes some achievements in the field of development of new electrocatalysts for H2 production/oxidation and their application for fuel cells, mainly focuses on the consideration of the catalytic activity of M[P2N2]2 2+ (M = Ni, Fe) complexes and other nickel structures which have been recently obtained.

Nickel anions [(MeCN)Ni(CF3)3]− and [Ni(CF3)4]2– were prepared by the formal addition of 3 and 4 equiv, respectively, of AgCF3 to [(dme)NiBr2] in the presence of the [PPh4]+ counterion. Detailed in...

The key intermediate palladacycles (mono-, bi-, and tetranuclear) with phosphonate, acetate, and other counterions in C(sp2)–H phosphonation are analyzed in terms of their redox properties, mutual ...

The synthesis, crystal structure, thermal stability, porosity and magnetic properties of three new layered coordination polymers [(M2(pQ)3)·4DMAA]n (M3+ = La3+ (1), Pr3+ (2), Nd3+ (3); pQ2− – the dianionic form of 2,5-dihydroxy-3,6-di-tert-butyl-para-quinone; DMAA = N,N′-dimethylacetamide) are reported. The coordination polymers obtained were investigated by solid-state electrochemistry which demonstrates multistep one-electron transformations caused by the presence of redox-active dioxolene ligands.

The reaction of (R)-1-(1-phenyl)ethyl-3-(O,O-diethylthiophosphoryl)thiourea with Cu(II) acetate is accompanied by copper reduction and leads to the formation of a chiral polynuclear Cu6L6 complex. In the crystalline phase the complex consists of six Cu(I) ions alternating with sulfur atoms in the central core, with all six ligands exhibiting similar 1,5-S,S-coordination modes. This structural multinuclear arrangement is preserved in solutions, while at the same time partial disproportionation is observed with the formation of complexes of lower dimensionality. Synchronous redox processes are observed for all six copper ions in the complex in the solid state. The mechanism of copper reduction with the ligand itself as a reducing agent is proposed.

The reaction between aryl substituted sodium 1,2,3-triphospholides or disodium bis(1,2,3-triphospholide) and [Fe(η6-(C6H5CH3)Cp]+[PF6]- in boiling diglyme results in pure 1,2,3-triphosphaferrocenes 1-3 or bis(1,2,3-triphosphaferrocene) 4, respectively, in good yields. The structure of all obtained 1,2,3-triphosphaferrocenes 1-4 has been extensively studied experimentally (NMR, UV-Vis spectroscopy, and X-ray analysis for 1 and 4) and quantum chemically. The electrochemical properties of 1,2,3-triphosphaferrocenes 1-4 in the solid state were studied for the first time and a reversible one-electron oxidation (E1/2 = 0.52-0.92 V vs. Fc+/Fc) was demonstrated for 1, 3, and 4. In the case of 1,4-bis(5-phenyl-4-(1,2,3-triphospaferrocenyl))benzene 4, consecutive oxidation in the solid state is observed in contrast to other 1,2,3-triphosphaferrocenes 1-3. According to the ESR data, the g-factor of the oxidized bis(1,2,3-triphosphaferrocene), 4 (g = 2.12) is different from the g-factors of oxidized 1,2,3-triphosphaferrocenes 1-3 (g = 2.01). This is the first example of multi(ferrocenyl) systems based on the phosphaferrocene motif, which in turn opens up a new fundamental platform for the preparation of compounds with stimuli-responsive properties.

Rational design and synthesis of efficient metal-organic frameworks (MOFs) as electrode modifiers for energy-related electrocatalytic applications are crucial for the development of clean-energy technologies. The present review focuses on recent work on robust earth-abundant heterogeneous catalysts based on pristine MOFs for the hydrogen evolution reaction (HER) and overall water splitting. These catalysts have been extensively studied as alternatives for noble metal-based ones, demonstrating "hydrogen economy" development prospects. In addition, novel strategies to enhance the conductivity, chemical stability and efficiency of MOF-based electrocatalysts are discussed. The best electrocatalysts even surpass the achievements of the platinum group of metals and MOF-derived catalysts in catalytic performance. The electrolytic cells with MOF-modified electrodes demonstrated excellent catalytic activity and can deliver a high current density at a voltage lower than that using the precious metal-based Pt/C cathodes and IrO2 anodes. In this review article, current approaches to design such MOF and MOF-modified electrode materials are summarized and analyzed.

A mild, efficient electrochemical approach to the site-selective direct C–H amidation of benzene and its derivatives with acetonitrile and benzonitrile has been developed. It has been shown that joint electrochemical oxidation of various arenes in the presence of a copper salt as a catalyst and nitriles leads to the formation of N-phenylacetamide from benzene and N-benzylacetamides from benzyl derivatives (up to 78% yield). A favorable feature of the process is mild conditions (room temperature, ambient pressure, no strong oxidants) that meet the criteria of green chemistry.

A selective noble-metal-free molecular catalyst has emerged as a fruitful approach in the quest for designing efficient and stable catalytic materials for CO2 reduction. In this work, we report that a sodium pectate complex of copper (PG-NaCu) proved to be highly active in the electrocatalytic conversion of CO2 to CH4 in water. Stability and selectivity of conversion of CO2 to CH4 as a product at a glassy carbon electrode were discovered. The copper complex PG-NaCu was synthesized and characterized by physicochemical methods. The electrochemical CO2 reduction reaction (CO2RR) proceeds at −1.5 V vs. Ag/AgCl at ~10 mA/cm2 current densities in the presence of the catalyst. The current density decreases by less than 20% within 12 h of electrolysis (the main decrease occurs in the first 3 h of electrolysis in the presence of CO2). This copper pectate complex (PG-NaCu) combines the advantages of heterogeneous and homogeneous catalysts, the stability of heterogeneous solid materials and the performance (high activity and selectivity) of molecular catalysts.

The title complexes were prepared, and their redox and catalytic properties in hydrogen evolution reaction were examined. The catalytic current increases in the presence of a proton source near the potential of the nickel(I/0) couple for a mixture of nickel(II) complexes with different ligands. Moreover, the catalytic activity of mixed-ligand complexes in the hydrogen evolution reaction was higher than that of a bis-chelated diphosphine nickel(II) complex.

The interest in organophosphorus compounds with a C-P bond is due to their wide use in various fields, especially in medicine and agrochemistry. Prominent examples of anti-cancer, antibacterial, and anti-HIV agents are therapeutic candidates containing a phosphonic acid group fragment. This review provides modern synthetic methods for obtaining phosphorylated aromatic and heteroaromatic compounds with the participation of complexes and salts of various metals developed in recent years as well modern protocol - electrochemical synthesis which allows carrying out reactions at room temperature and normal pressure with no additional oxidants or bases. Herein, we demonstrate new trends and evolution of phosphorylation reactions in catalysis.

Copper or silver-catalyzed direct C(sp2)–H/N–H electrochemical cross-coupling of phthalimide and heterocyclic arenes (2-phenylpyridine, benzo[h]quinoline, benzoxazole, and benzothiazole, etc.) for ...

Unusual application of ionic liquids as the promoter for selective white phosphorus tetrahedron opening and reagent in the electrochemical reaction was described. New single-stage electrochemical synthesis of esters of phosphoric acids from white phosphorus in the presence of ionic liquid in alcohol medium has been proposed in mild conditions. One hundred percent conversion of P4 to soluble organophosphorus derivatives was observed. Ionic liquid promotes the opening of a tetrahedron of white phosphorus, acting as an electrophilic reaction component, as well as an electrolyte and a reagent. The dialkylimidazole diethylphosphonate with C–P bond, difficult of access by other approaches, was prepared with good yields.

Metal-organic frameworks [M2L3]n have been synthesized using ferrocene-based ligand bearing phosphinic groups L = 1,1’-ferrocenediyl-bis(H-phosphinic acid)) and M(III) = Eu, Dy. Structures of compl...

The work describes the synthesis of the 2D[Mn(H2O)2(Fc(PHOO)2)⋅2H2O]n using manganese nitrate. The energy of Li-Fc interaction has been estimated quantum-chemically. It was shown that substituent o...

The deprotonation of N-2,6-diisopropylphenyl-substituted benzoxazolium tetrafluoroborate 1 with NaH results in the formation of electron-rich diaminodioxaethylene 2. The radical cation salt 2·+·BF4– is found to be an intermediate product in the redox reaction leading from 1 to 2.

The present work introduces a facile synthetic route for efficient doping of [NiII(bpy)x] into silica nanoparticles with various sizes and architectures. Variation of the latter results in different concentrations of the NiII complexes at the interface of the composite nanoparticles. The UV-Vis analysis of the nanoparticles reveals changes in the inner-sphere environment of the NiII complexes when embedded into the nanoparticles, while the inner-sphere of NiII is invariant for the nanoparticles with different architecture. Comparative analysis of the electrochemically generated redox transformations of the NiII complexes embedded in the nanoparticles of various architectures reveals the latter as the main factor controlling the accessibility of NiII complexes to the redox transitions which, in turn, controls the electrochemical behavior of the nanoparticles. The work also highlights an impact of the nanoparticulate architecture in catalytic activity of the NiII complexes within the different nanoparticles in oxidative C–H fluoroalkylation of caffeine. Both low leakage and high concentration of the NiII complexes at the interface of the composite nanoparticles enables fluoroalkylated caffeine to be obtained in high yields under recycling of the nanocatalyst five times at least.

The interaction of manganese(II) phthalocyanine with 7,7,8,8-tetracyanoquinodimethane and its perfluoro derivative proceeds with the oxidation of Mn and the reduction of the acceptor molecules to give the first mixed single crystals of manganese(III) phthalocyanine with TCNQ/F4-TCNQ radical anions. The crystals have unusual structures with C–H⋯π interactions between the ions and their orthogonal arrangement, as well as remarkable redox properties. The charge transfer was proved by spectroscopic and magnetic studies.

Transition metal-catalyzed C-H activation has emerged as a powerful tool in organic synthesis and electrosynthesis as well as in the development of new methodologies for producing fine chemicals. In order to achieve efficient and selective C-H functionalization, different strategies have been used to accelerate the C-H activation step, including the incorporation of directing groups in the substrate that facilitate coordination to the catalyst. In this review, we try to underscore that the understanding the mechanisms of the catalytic cycle and the reactivity or redox activity of the key metal cyclic intermediates in these reactions is the basis for controlling the selectivity of synthesis and electrosynthesis. Combination of the electrosynthesis and voltammetry with traditional synthetic and physico-chemical methods allows one to achieve selective transformation of C-H bonds to functionalized C-C or C-X (X=heteroatom or halogen) bonds which may encourage organic chemists to use it in the future more often. The possibilities and the benefits of electrochemical techniques are analyzed and summarized.

The present work introduces both synthesis of silica nanoparticles doped with CoII ions by means of differently modified microemulsion water-in-oil (w/o) and St&ouml, ber techniques and characterization of the hybrid nanoparticles (CoII@SiO2) by TEM, DLS, XRD, ICP-EOS, SAXS, UV-Vis, and UV-Vis/DR spectroscopy and electrochemical methods. The results reveal the lack of nanocrystalline dopants inside the hybrid nanoparticles, as well as no ligands, when CoII ions are added to the synthetic mixtures as CoII(bpy)3 complexes, thus pointing to coordination of CoII ions with Si-O- groups as main driving force of the doping. The UV-Vis/DR spectra of CoII@SiO2 in the range of d-d transitions indicate that St&ouml, ber synthesis in greater extent than the w/o one stabilizes tetrahedral CoII ions versus the octahedral ions. Both cobalt content and homogeneity of the CoII distribution within CoII@SiO2 are greatly influenced by the synthetic technique. The electrochemical behavior of CoII@SiO2 is manifested by one oxidation and two reduction steps, which provide the basis for electrochemical response on glyphosate and HP(O)(OEt)2 with the LOD = 0.1 &mu, M and the linearity within 0.1&ndash, 80 &mu, M. The St&ouml, ber CoII@SiO2 are able to discriminate glyphosate from HP(O)(OEt)2, while the w/o nanoparticles are more efficient but nonselective sensors on the toxicants.

New 3D Ni and Co redox-active metal–organic frameworks based on ferrocenyl diphosphinate and 4,4′-bipyridine ligands have been synthesized, characterized by single crystal X-ray diffraction and spectroscopic techniques and explored as stable electrocatalysts capable of meeting two important parameters: the overpotential and Tafel slope (TS) in the hydrogen evolution reaction (HER). The electrochemical studies suggest that the reaction kinetics of a Ni-MOF (1) catalyst is more favorable than that of a Co-MOF (2) catalyst. Particularly, Ni-MOF exhibits better HER performance with an overpotential of 350 mV at a current density of 10 mA cm−2, a small TS of 60 mV dec−1 and superior long-term durability (of up to 10 000 cycles), ranking it among the most active non-noble metal-based molecular electrocatalysts. The introduction of a 4,4′-bpy linker in 2 significantly changes the catalytic properties in an organic or aqueous environment compared to 1D cobalt polymers based on ferrocenyl diphosphinate. For Co-MOF 2, there is a significant decrease in the overvoltage by ∼440 mV in comparison with the 1D Co polymer in an organic medium and by 50 mV in an aqueous medium. The TS changes from 120 to 65 mV dec−1 when moving from 1D CofcdHp to a 3D structure of 2. Thus, a 4,4′-bpy linker reduces the overvoltage and gives more favorable HER kinetics (lower TS). These results provide important guidelines for the rational design of non-precious metal electrocatalysts.

The temperature and substrate dependent luminescence of terbium complexes with calix[4]arene derivatives makes them promising building blocks of nanosensors. Thus, calix[4]arene 1,3-diketones in 1,3-alternate and cone isomeric forms bearing buthyl, dodecyl, nonyl and bromine substituents are introduced as ligands forming luminescent Tb3+ complexes in basified DMF solutions. The structure variation of the ligands allows to highlight buthyl-substituted derivative of calix[4]arene 1,3-diketone in 1,3-alternate isomeric form as the optimal structure. The detailed studies of the complex stoichiometry by means of UV-Vis and H1 NMR diffusion spectroscopy methods reveal 2:2 stoichiometry as the main for the calix[4]arene 1,3-diketones in 1,3-alternate isomeric form. The predominance of 2:2 over 1:1 and 1:2 (Tb:L) complex stoichiometries for the buthyl-substituted ligand was confirmed by comparison of the quantum chemically calculated thermochemical parameters of their complex formation. However, the 2:2 complex formation is either restricted for their dodecyl-substituted derivative or interferes with the 1:2 stoichiometry for the bromo-substituted counterpart. The conversion of the Tb3+ complexes from the DMF solutions to the PSS-stabilized colloids through the solvent-exchange procedure reveals the unfavorable effect of the nonyl- and dodecyl-substituted ligands on aggregation behavior of the colloids. Thus, 2:2 terbium complex with buthyl-substituted ligand in 1,3-alternate isomeric form is the optimal basis for production of the luminescent PSS-colloids with high colloid stability. The Tb3+- luminescence of the colloids exhibit the enhanced sensitivity to both environmental pollutant glyphosate with LOD = 1.97 nM and temperature changes within the physiological temperature range with SI = −4.67 K-% at 323 K.

Catalyst capable to operate in cathode and anode spaces simultaneously was found. Electrochemical regeneration of active form of catalyst Co2+bpy (1%) under oxidative as well as reductive condition...

Recent achievements of electrochemical efficient and atom-economical catalytic methods for the formation of aromatic carbon-phosphorus bonds are summarized in this mini-review. Electrochemical reac...

The chemistry of organoelemental compounds including carbon-phosphorus derivatives is now one of the most rapidly developing fields of research, regarding both fundamental science and solution of applied problems. Extensive opportunities for the synthesis of organophosphorus compounds are opened up by the use of unconventional methods, first of all, electrochemical ones, which combine the benefits of usual homogeneous chemistry in solution and electrochemistry, where reactants are generated at the electrodes directly in the reaction system. The interest in the organic electrosynthesis is caused by several factors, including mild conditions (room temperature, atmospheric pressure), the possibility of conducting reactions in a closed system with a low concentration of the catalyst, which is readily regenerated. This mini-review generalizes the achievements in the field of development of new electrochemical, efficient and atom-economical, catalytic methods for the formation of aromatic carbon – phosphorus bonds and some historical background of these approaches.

This paper elucidates the redox properties and reactivity of a number of cyclometalated nickel(II) complexes in oxidation processes. Original and robust procedures for the synthesis of nickelacycles with two cyclometalated moieties and halogenated nickelacycles were developed. The complexes were studied by means of electrochemical, ESR, DFT, and single-crystal XRD methods. Notable features of the nickelacycles are unusually low oxidation potentials. Upon electrochemical oxidation the complexes produce carbon–carbon and carbon–heteroatom coupled products, the ratio of which can be tuned by the conditions applied.

For the first time the nonlinear optical (NLO) activity of indolizine-based push-pull chromophores with different acceptor moieties was studied and compared. All the chromophores demonstrate strong absorption band in the visible (orange-red) part of the spectrum, with e of ca. 105 L∙cm−1∙M−1 notably dependent on medium polarity. Replacement of Ph-TCF acceptor by Hex-TCP one results in twofold increase of the first hyperpolarizability value. Energy gaps estimated by electrochemical methods decrease in the series ΔE1a,b>ΔE3a,b>ΔE2a,b for compounds with Ph-TCF, DCM and Hex-TCP acceptors, respectively, good agreement with DFT estimations is obtained. The nonlinear optical coefficient for poled PMMA-based films, containing 20 wt% of isomeric indolizine chromophores with weaker dicyanomethylene (DCM) acceptor and with π- bridge expanded by isophorone moiety, achieves 36 pm/V, thus exceeding those for materials containing chromophores with stronger Ph-TCF or Hex-TCP acceptors and with short vinylene π-bridge.

Four chromophores belonging to a new class of push-pull chromophores with divinylphenylquinoxaline moieties have been designed and synthesized. The structure-property relationship was systematically investigated; the effect of the conformation on the value of chromophores first hyperpolarizability is found to be inessential. Quinoxaline-based chromophore with TCF acceptor and 7-dimethylanilinovinyl moiety displays the combination of favorable characteristics: the high value of the first hyperpolarizability, the small HOMO-LUMO energy gap, the blue shift of the absorption maximum relative to the chromophores with other divinylhetaryl or polyene π-bridges and ultrahigh thermal stability. This chromophore may be considered as a perfect candidate for the development of effective electro-optic materials.

Palladium nanoparticles–polypyrrole composite (Pd/PPy) catalyzes the addition of perfluoroalkyl halides to olefins to produce a variety of products with good yields. An effective fluoroalkylation technique tested with various olefins, fluoroalkyl halides and Pd/PPy was developed. The reaction proceeds highly efficient under mild phosphine-free reaction conditions with different substrates, easy catalyst recycling and provides a general and straightforward access to fluoroalkylated products. Furthermore, we were able to control whether the addition of perfluoroalkyl occurs with various monomer (fluoroalkylated alkene or alkane with RF and OH moieties) or dimer formation (under electrochemical conditions).

Joined electrolysis of arenes (benzene or coumarin derivatives) and diethyl-H-phosphonate (EtO)2P(O)H in the presence of [CoCl2(bpy)] catalyst (5%) in an ethanol-aqueous solution in reductive conditions allows obtaining the desired products in a single step by aromatic C–H bonds phosphonation with yields up to 70%. The only by-product is hydrogen; the reaction proceeds at room temperature and does not require specially added reducing agents and oxidants or other initiators. Radical mechanism has been confirmed for the catalytic reaction proceeding via bicobalt phosphonates with Co–P bond, the structure of which also has been identified.

New (2-(4-methylpyrazol-1-yl)phenyl) platinum(II) (dibenzoylmethane) Pt(mpp)(dbm) complex based on 4-methylpyrazole was synthesized using a simple scheme. Its crystal structure, spectral and electrochemical properties were studied. The extra pure green (CIE chromacity coordinates X = 0.1419, Y = 0.7444) electroluminescence for OLED structures was obtained.

The present work considers main achievements and modern trends in methods of synthesis of organophosphorus heterocyclic compounds through mainly radical phosphorylation of the C(sp2)–H bonds of unsaturated compounds catalyzed by metal salts and complexes. It also summarizes new ways of obtaining both phosphorous cycles (P-cycles) and heterocycles with another heteroatom (N, O, etc.) containing an external organophosphorus substituent. The most important and promising areas of recent years including the synthesis of 1-benzophospholes, arylphosphonates, phosphines, and phosphine oxides are highlighted. The reactions of phosphorylation/cyclization with acetylene, 2-isocyanobiphenyl, alkynoates, and olefins are analyzed. The assumed mechanisms and intermediates in the reactions of formation of the C–P bond are considered. New 1-benzophosphole oxides possessing photochromic, fluorescent, and some other optical properties are described. The work draws attention to the potential of this intensively developed direction of the organoelemental chemistry in last 5 years.