Bis Metal Complexes Research Articles

A Fluorescent Sensor Array for the Discrimination of Nucleotide Phosphates

AbstractChemosensors that can discriminate between nucleotide phosphates are difficult to prepare. Here we describe the use of a sensing array comprising metal complexes of bis(dipicolylamino)‐functionalised linear peptide based fluorescent sensors for the discrimination of nucleotide phosphates. We demonstrate that through the rational incorporation of additional sensor elements the discriminatory power of the array can be improved. An array incorporating two peptides in combination with four metal ions was able to successfully discriminate all triphosphates and diphosphates tested. When monophosphates were included in the analysis, 91 % of the analytes (blank, AMP, ADP, ATP, CMP, CDP, CTP, GMP, GDP, GTP, UMP, UDP and UTP) could be correctly classified, with all classification errors related to monophosphates.

Activation of CO Using a 1,2‐Disilylene: Facile Synthesis of an Abnormal N‐Heterocyclic Silylene

AbstractReaction of the 1,2‐disilylene, [{ArC(NDip)2}Si]2 1 (Dip=2,6‐diisopropylphenyl, Ar=4‐C6H4But), with CO proceeds via insertion of CO into one Si−N bond, and Si−Si bond cleavage, to cleanly give the bis(silylene), {ArC(NDip)2}Si(:)O Ar 2, under ambient conditions. The reaction can be partially reversed when solutions of 2 are subjected to UV irradiation. The five‐membered heterocyclic fragment of 2 represents the first silicon analogue of an “abnormal” N‐heterocyclic carbene (aNHC), a view which is substantiated by a computational analysis of the compound. Reaction of 2 with [Mo(CO)6] under UV light affords the chelate complex, [Mo(CO)4(κ2‐Si,Si‐2)] 3, while reaction with [Fe(CO)5] gives the unusual silyleneyl bridged complex, [{Fe2(CO)6}{μ‐Si[(NDip)2CAr]}2] 4. The same coordination complexes can be accessed by reaction of 1 with [Mo(CO)6] or [Fe(CO)5] under UV light. As is the case for aNHCs, d‐block metal complexes of bis(silylene) 2 could prove useful as bespoke catalysts for organic transformations.

Activation of CO Using a 1,2-Disilylene: Facile Synthesis of an Abnormal N-Heterocyclic Silylene.

Reaction of the 1,2-disilylene, [{ArC(NDip)2 }Si]2 1 (Dip=2,6-diisopropylphenyl, Ar=4-C6 H4 But ), with CO proceeds via insertion of CO into one Si-N bond, and Si-Si bond cleavage, to cleanly give the bis(silylene), {ArC(NDip)2 }Si(:)O Ar 2, under ambient conditions. The reaction can be partially reversed when solutions of 2 are subjected to UV irradiation. The five-membered heterocyclic fragment of 2 represents the first silicon analogue of an "abnormal" N-heterocyclic carbene (aNHC), a view which is substantiated by a computational analysis of the compound. Reaction of 2 with [Mo(CO)6 ] under UV light affords the chelate complex, [Mo(CO)4 (κ2 -Si,Si-2)] 3, while reaction with [Fe(CO)5 ] gives the unusual silyleneyl bridged complex, [{Fe2 (CO)6 }{μ-Si[(NDip)2 CAr]}2 ] 4. The same coordination complexes can be accessed by reaction of 1 with [Mo(CO)6 ] or [Fe(CO)5 ] under UV light. As is the case for aNHCs, d-block metal complexes of bis(silylene) 2 could prove useful as bespoke catalysts for organic transformations.

Coinage Metal Complexes of Bis(quinoline-2-ylmethyl)phenylphosphine-Simple Reactions Can Lead to Unprecedented Results.

The different coordination behavior of the flexible yet sterically demanding, hemilabile P,N ligand bis(quinoline‐2‐ylmethyl)phenylphosphine (bqmpp) towards selected CuI, AgI and AuI species is described. The resulting X‐ray crystal structures reveal interesting coordination geometries. With [Cu(MeCN)4]BF4, compound 1 [Cu2(bqmpp)2](BF4)2 is obtained, wherein the copper(I) atoms display a distorted square planar and square pyramidal geometry. The steric demand and π‐stacking of the ligand allow for a short Cu⋅⋅⋅Cu distance (2.588(9) Å). CuI complex 2 [Cu4Cl3(bqmpp)2]BF4 contains a rarely observed Cu4Cl3 cluster, probably enabled by dichloromethane as the chloride source. In the cluster, even shorter Cu⋅⋅⋅Cu distances (2.447(1) Å) are present. The reaction of Ag[SbF6] with the ligand leads to a dinuclear compound (3) in solution as confirmed by 31P{1H} NMR spectroscopy. During crystallization, instead of the expected phosphine complex 3, a tris(quinoline‐2‐ylmethyl)bisphenyl‐phosphine (tqmbp) compound [Ag2(tqmbp)2](SbF6)2 4 is formed by elimination of quinaldine. The Au(I) compound [Au2(bqmpp)2]PF6 (5) is prepared as expected and shows a linear arrangement of two phosphine ligands around AuI.

Microwave assisted catalytic oxidation of cyclohexene, cyclohexane, cyclooctane and styrene with metal complexes of bis(azo-imine) ligands supported on mesoporous silica

Novel multifunctional bis(azo-Schiff base) ligands supported on mesoporous silica and their Cu(II), Co(II), Mn(II) and Ni(II) complexes were synthesized and characterized with the techniques of FT-IR, TGA, SEM, EDX, ICP-OES (metal content) and C, H, N content analyses. The synthesized complexes were tried as catalysts in the oxidation of cyclohexene, cyclohexane, cyclooctane and styrene substrates under microwave power. The Co(II) complex of silica-supported bis(azo-Schiff base) ligand derivatized from m-xylylenediamine and 2,4-dihydroxybenzaldehyde (L2) behaved as the best catalyst in cyclohexane oxidation to cyclohexanol with 73.84% selectivity. The complexes of Cu(II) were very selective to the yield of 2-cyclohexen-1-ol synthesis from the oxidation of cyclohexene under microwave power especially L2-Cu(II) with 64.29% selectivity. According to the calculated selectivities of the complexes in the catalytic reactions, it can be said that the complexes were not active in cycloctane and styrene oxidation.

Synthesis, characterization, and some metal complexes of bis(isocyanide)disiloxane, showing catalytic activity

AbstractIsocyanides (isonitriles) are unique organic compounds that contain a formally divalent carbon. Herein, the synthesis of 1,3‐bis(isocyanopropyl)tetramethyldisiloxane was performed by a modified carbylamine method, using a phase transfer agent. Spectral methods (nuclear magnetic resonance [NMR], Fourier transform infrared spectroscopy [FT‐IR], and electrospray ionization mass spectrometry [ESI‐MS]) were used to confirm the structure. Energy gap of 1.86 eV (measured by diffuse reflectance spectroscopy [DRS]), high dielectric permittivity (15 at 10 kHz), and conductivity value in the order of 10−7 S·cm−1 place this compound in the range of wide‐bandgap semiconductors. The synthesis of Pt, Ag, and Fe metal complexes without organic co‐ligands and their catalytic activity were also investigated. The Pt complex was active in hydrosilylation reaction and in reduction of p‐nitrophenol, whereas the Ag complex was found effective in alkaline decomposition of hydrogen peroxide. The Fe complex is a new and cheap heterogeneous hydrosilylation catalyst and also showed very good catalytic behavior in heterogeneous Fenton‐like photodecomposition of Congo Red in various photo‐irradiation conditions, with 100% color removal efficiency after 60 min under sunlight. Thus, a simple path for siloxane‐containing materials with promising applications is open.

First row transition metal complexes of bis(3,5-dimethyl pyrazolyl)methane: Synthesis, molecular structure and antibacterial properties

A series of nine transition metal complexes was synthesized by reacting bis(3,5-dimethylpyrazolyl)methane (BP) with the respective metal chlorides in 1:1 and 2:1 stochiometric proportions. The complexes were duly characterized by molar conductivity measurement, IR, UV, NMR spectroscopy and elemental analysis. Using X-ray analysis, solid state molecular structures of the complexes C3 and C8 were determined. The molecular structures and the stoichiometry of the obtained complexes were found to be governed by the steric factors of the ligand substituents. The prepared compounds were found to be bactericidal against the four bacterial stains tested, however with high MIC/MBC values.

Precious metal complexes of bis(pyridyl)allenes: synthesis and catalytic and medicinal applications.

The incorporation of donor-type substituents on the allene core opens up the possibility of coordination complexes in which the metal is bonded to the donor groups, with or without interaction with the double bond system. Despite the challenges in the synthesis of such allene-containing metal complexes, their unique 3D environments and dual functionality (allene and metal) could facilitate catalysis and interaction with chemical and biological systems. Bis(pyridyl)allenes are presented here as robust ligands for novel Pd(II), Pt(IV) and Au(III) complexes. Their synthesis, characterisation and first application as catalysts of benchmark reactions for Pd, Pt and Au are presented with interesting reactivity and selectivities. The complexes have also been probed as antimicrobial and anticancer agents with promising activities, and the first studies on their unusual interaction with several DNA structures will open new avenues for research in the area of metallodrugs with new mechanisms of action.

Structural diversity in the solid-state architectures of bis(4-pyridyl)acetylene and its derivatives

The crystals of bis(4-pyridyl)acetylene are orthorhombic and belong to the space group Fddd. Solid-state investigation using conventional and Hirshfeld analytical techniques revealed valuable data and structural diversities that explain the wide gap between established crystal reports of co-crystals and metal organic frameworks and the pure form of the title compound. Hirshfeld surface analysis in this wise has proved to be a useful tool in unravelling complex intermolecular interactions and simplifying them at the 2D and 3D levels using sub-tools such as fingerprint plots and electrostatic potential surfaces. Both techniques have shown that the H∙∙∙Npyr interactions in the title compound are shorter than those in its polymorphic counterpart by 0.2 Å. The more stable network provided by hetero-molecular interactions in co-crystals and metal complexes of bis(4-pyridyl)acetylene shed light on their lengthy existence compared to the less favorable homo-molecular interactions in pure molecules of bis(4-pyridyl)acetylene.

Metal-complex compounds as additives to the synthetic oils

N-(2-hydroxybenzal (naphtal)-dodecylamines – Shiff bases and some khelate complexes of Cu (II), Co (II) and Ni (II) transition metals with their participation were synthesized. The effects of obtained metal complexes of Bis-[N-(2-oxisalycilal (naphtal) octadecyliminates] on the performance of synthetic oils were studied as well. It is justified that obtained compounds exhibit enhanced inhibiting activity, are superior in the efficiency to the well-known inhibitor phenyl- α-naphthylamine, and comparable to tricresyl phosphate in anti-wear properties.

Bis-Metal Complexes of Doubly N-Confused Dioxohexaphyrins as Potential Near-Infrared-II Photoacoustic Dyes.

We investigated the detailed photophysical properties of a series of bis-metal (Zn and Cu) dioxohexaphyrin complexes as potential second near-infrared (NIR-II)-light responsive dyes. A cisoid-configured 28π-electron-conjugated dioxohexaphyrin analogue (c-3a) containing two peculiar "confused pyrrole" moieties in the framework is identified as a reduced isomer derivative of a transoid 26π-dioxohexaphyrin (t-2a). The symmetry-altered structure of c-3a affords a heteroleptic inner environment within the NNNN/NNOO donor core, which imparts its highly flexible electronic features and nonplanar geometry. The macrocycle c-3a can be transformed into the corresponding 26π-electron congener (c-2a) having a coplanar rectangular structure by unique solvent-mediated redox reactivity. Furthermore, upon metal complexation, saddle-distorted bis-metal complexes (c-M2-2a) were formed as the 26π-conjugated structural isomer of the trans-dioxohexaphyrin species (i.e., t-M2-2a). These isoelectronic dioxohexaphyrins demonstrate precise geometry-dependent photophysical properties. Broad tailing NIR-II absorption, weak emissive character, and rapid-decay of the S1 state are observed for c-Zn2-2a. In contrast, the coplanar t-M2-2a exhibits efficient photoacoustic response upon laser excitation with NIR-II light (λ > 1000 nm). To the best of our knowledge, this is the first example of an expanded porphyrin-based photoacoustic contrast agent responsive to NIR-II light.

A detailed study of intermolecular interactions, electronic and vibrational properties of the metal complex bis(uracilato)diammine copper(ii) dihydrate

Density Functional Theory (DFT) calculations were performed with the aim of investigating the vibrational, electronic and structural properties of [Cu(uracilato-N1)2 (NH3)2]⋅2H2O complex. The IR and Raman spectra were recorded leading to a complete analysis of the normal modes of vibration of the metal complex.A careful study of the intermolecular interactions observed in solid state was performed by using the Hirshfeld surface analysis and their associated 2D fingerprint plots. The results indicated that the crystal packing is stabilized by NH⋯O hydrogen bonds and π-stacking interactions. In addition, CH···π interactions were also observed.Time-dependent density functional theory (TD-DFT) calculations revealed that all the low-lying electronic states correspond to a mixture of intraligand charge transfer (ILCT) and ligand-to-metal charge transfer (LMCT) transitions.Finally, Natural Bond Orbital (NBO) and Atoms in Molecules (AIM) analysis were performed to shed light on the intermolecular interactions in the coordination sphere.

Hetero Cu(III)-Pd(II) Complex of a Dibenzo[g,p]chrysene-Fused Bis-dicarbacorrole with Stable Organic Radical Character.

Bis-dicarbacorrole (bis-H3) with two adj-CCNN subunits was synthesized by incorporating a dibenzo[g,p]chrysene moiety into the macrocyclic structure. The two trianionic cores in bis-H3 can stabilize two Cu(III) ions (bis-Cu) or concurrently a Cu(III) cation and a Pd(II) ion in the form of a hetero bis-metal complex (mix-Cu/Pd). As prepared, mix-Cu/Pd displays organic π radical character, as confirmed by various techniques, including electron paramagnetic resonance spectroscopy, cyclic voltammetry, femtosecond transient absorption measurements, and DFT calculations. Radical formation is ascribed to one-electron transfer from the dicarbacorrole backbone to the Pd center allowing the d8 Pd(II) center to be accommodated in a square planner coordination geometry. Nucleus-independent chemical shift and anisotropy of the induced current density calculations provide support for the conclusion that bis-H3 and bis-Cu both display antiaromatic character and contain two formally 16 π-electron dicarbacorrole subunits. On this basis, we suggest that mix-Cu/Pd is best considered as containing a fused 15 π-electron nonaromatic radical subunit and a 16 π-electron antiaromatic subunit. The spectroscopic observations are consistent with these assignments.

Coordinative Layer-by-Layer Assembly of Thin Films Based on Metal Ion Complexes of Ligand-Substituted Polystyrene Copolymers and Their Use as Separation Membranes

Polystyrene copolymers containing either 4′-vinyl-2,2′:6′,2″-terpyridine (P1) or 2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-4-yloxy)-methacrylate (P2) as comonomers are prepared and studied on metal ion coordination in solution and coordinative sequential assembly of films and membranes. Permeation and separation of ions and neutral aromatic molecules across the membranes are investigated. UV–vis titration of P1 with zinc acetate in chloroform/methanol (25:1) indicates formation of 2:1 ligand:metal bis-complexes, while titration of P2 led to 1:1 monocomplexes. It is demonstrated that coordinative interactions between the ligand groups and metal ions such as Zn(II) or Cu(II) can be used for layer-by-layer assembly of ultrathin films on solid quartz supports and porous supporting membranes. Formation of coordination polymer assemblies is characterized using UV-spectroscopy, quartz crystal microbalance measurements, scanning electron microscopy, and thickness measurements. Coordinative films prepared on porous polyacrylonitrile/polyethylene terephthalate supporting membranes exhibit a selective transport of ions and small molecules. Ion transport in aqueous and alcoholic solution is controlled by a sieving effect and by electrostatic rejection at the ligand–metal ion complexes in the membrane. The transport of organic aromatic molecules is only controlled by the sieving effect. Separation factors α(NaCl/BaCl2) up to 4.2 and α(naphthalene/perylene) up to 4.8 are found.

Role of Dispersion in Metallophilic Hg···M Interactions (M = Cu, Ag, Au) within Coinage Metal Complexes of Bis(6-diphenylphosphinoacenaphth-5-yl)mercury.

The previously reported bis(6-diphenylphosphinoacenaphth-5-yl)mercury (1) was used as ligand for the preparation of the copper(I) complexes, 1·CuCl and [1·Cu(NCMe)]BF4, which were characterized by multinuclear NMR spectroscopy and X-ray crystallography. DFT calculations employing topological analysis of the electron and electron pair densities within the AIM and ELI-D space-partitioning schemes revealed significant metallophilic Hg···Cu interactions. Evaluation of noncovalent bonding aspects according to the noncovalent interaction (NCI) index was applied not only for the Cu complexes 1·CuCl and [1·Cu(NCMe)]BF4 but also for the previously reported Ag and Au complexes, namely, [1·MCl] (M = Ag, Au) and [1·M(NCMe)n]+ (M = Ag, n = 2; M = Au, n = 0), and facilitated the assignment of attractive dispersive Hg···M interactions with the Hg···Cu contacts being comparable to the Hg···Ag but weaker than the Hg···Au interactions. The localization of the attractive noncovalent bonding regions increases in the order Cu < Ag < Au.

Bis(5,7-dimethyl-8-hydroxyquinolinato)beryllium(II) complex as optoelectronic material

Metal complex bis(5,7-dimethyl-8-hydroxyquinolinato)beryllium(II) as a light emissive material had been synthesized and characterized by various spectral techniques. The beryllium complex had high thermal stability (>250°C) as well as high glass transition temperature (>115°C). The prepared metal chelate had a strong photoluminescence (PL) emission at 558nm (FWHM=72nm) and electroluminescence (EL) at 561nm (FWHM=55nm) with good efficiency. Density functional theoretical calculations have been performed to demonstrate the three-dimensional geometries and the frontier molecular orbital energy levels of this metal complex. Sublimed metal chelate formed thin transparent film and found appropriate material for exploring their opto-electronic applications. OLED device was fabricated using this metal complex by vacuum deposition technique with the device configuration of ITO/TPD(30nm)/Be-complex(30nm)/BCP(6nm)/Alq3(28nm)/LiF(1nm)/Al(100nm). The emitted color of the EL device showed Commission Internationale d'Eclairage (CIE) color coordinates as x=0.625, y=0.366 corresponding to greenish yellow color. The maximum luminescence of the fabricated device was reported 1364Cd/m2 at 22V. The maximum current efficiency and power efficiency were 1.75Cd/A and 0.51lm/W at 10V respectively for the fabricated OLED device.

Bismetal Complexes of 5,20-Bis(5-formyl-2-pyrrolyl)-[26]hexaphyrin(1.1.1.1.1.1) Exhibiting Strong Near-Infrared Region Absorptions.

[26]Hexaphyrin(1.1.1.1.1.1) bearing two 5-formyl-2-pyrrolyl groups at the 5- and 20-positions was prepared by cross-condensation of 5,10-bis(pentafluorophenyl)-substituted tripyrrane with 2,5-diformylpyrrole as an effective binuclear metal-coordinating ligand, owing to the two hemiporphyrin-like NNNN pockets. In fact, metalation of this hexaphyrin with Zn(II) , Cu(II) , and Pd(II) salts proceed smoothly at room temperature to give the corresponding bismetal complexes that displayed remarkably redshifted absorption spectra reaching deep into near infrared region. These redshifted absorption bands are ascribed, through electrochemical investigations and DFT calculations, to two structural motifs: the N-metalopyrrole substructure that elevates the HOMO level due to the electron-donating property and the two coordinated metal ions that serve as Lewis acids to lower the LUMO level.

Group 12 Metal Complexes of Bis-[2-{1,3-dioxane-2-yl} Ethyl] Telluride (L1) and 2-{2-(4-Fluoro Phenyl Telluro) Ethyl}-1,3-dioxane (L2): Synthesis, Spectral Characterization and Crystal Structure of Oxidized Product of [HgBr2.L1

GRAPHICAL ABSTRACT

Synthesis, characterization and antimicrobial studies of mono and bimetallic trinuclear transition metal complexes of bis(N2 ,N2 -acetylacetonehydrazonato)- N1 ,N1 -benzil dihydrazone (BAHBD) with CuII, NiII and CoII ions

Synthesis, characterization and antimicrobial studies of mono and bimetallic trinuclear transition metal complexes of bis(N2 ,N2 -acetylacetonehydrazonato)- N1 ,N1 -benzil dihydrazone (BAHBD) with CuII, NiII and CoII ions

A study of acridine and acridinium-substituted bis(terpyridine)zinc(ii) and ruthenium(ii) complexes as photosensitizers for O2 (1Δg) generation

The homoleptic zinc(II) and ruthenium(II) metal complexes of bis(tridentate) 9-acridine and 10-methyl-9-acridinium-substituted terpyridines were tested for their suitability as triplet photosensitizers (PS) using the photooxidation of 1,5-dihydroxynaphthalene (DHN) to Juglone as a model reaction. Singlet oxygen (O2(1)Δg) generation is superior or comparable to Ru(bpy)3(2+) for the acridine complexes, whereas the acridinium complexes are ineffective. The molecular structure of the bis(9-(5-([2,2':6',2''-terpyridin]-4'-yl)thien-2-yl)-10-methylacridinium)zinc(II) complex ([Zn(MeATT)2][PF6]4) is determined by X-ray structure analysis, whereas for other complexes DFT calculations were performed for structural parameters to obtain insights into their electronic properties.