Synthesis, characterization, and polarized luminescence properties of platinum(II) complexes having a rod-like ligand

We have synthesized a series of platinum (Pt) complexes having a rod-like ligand: 'Pt(F(2)PPy)acac', 'Pt(12F(2)PPy)acac', and 'Pt(12F(2)PPyO4)acac'. The crystal form of Pt(12F(2)PPy)acac was successfully determined to be triclinic by single-crystal X-ray structural analysis. The molecules were parallelly aligned in the unit cell. Monomer and excimer emissions of Pt(12F(2)PPy)acac were observed in hexane solution, poly(methyl methacrylate) film, and various nematic LCs. Homogeneous LC cells with the Pt complex/LC mixtures exhibited polarized optical emission resulting from monomer and excimer states. The PL intensity perpendicular to the orientation direction was higher than the parallel one in the whole wavelength region of the Pt complex and the polarization ratio of the excimer was higher than that of the monomer. The polarization ratios of the excimers were estimated to be 1.4-2.5 in nematic LC at room temperature, and decreased gradually with increasing temperature. The polarization ratios of Pt(12F(2)PPyO4)acac were higher than those of Pt(F(2)PPy)acac and Pt(12F(2)PPy)acac in all the LCs.     

Pyridine solvated dioxouranium complex with salen ligand: Synthesis,characterization and luminescence properties

A new derivative of dioxouranium(VI) salen complex, [UO2(L)(pyridine)], where [L = N,N′-Bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine] is synthesized and characterized by elemental analysis (C, H, N), FT-IR, ESI-MS spectrometry, UV/Vis, fluorescence, ¹H and ¹³C NMR spectroscopy and thermal gravimetric (TG) study. Furthermore, the single crystal X-ray diffraction measurements of the complex were carried out at 100 and 273 K. The crystal structure measurements revealed that the complex has distorted pentagonal bipyramidal geometry with uranium atom located at the centre and bonded to two phenoxy oxygen and two azomethine nitrogen in tetradenate fashion and one nitrogen from pyridine making it seven coordinated. In addition, the photoluminescence property of the complex was also recorded.     

Synthesis,characterization, and catalytic properties of a cobalt(II) complex supported by an amine-bis(phenolate) ligand

A cobalt(II) complex [L′CoPy] 1 was prepared by the reaction of dimethylaminoethylamino-N,N-bis(2,4-dibromo)phenol (H₂L′) with CoCl₂. Electrochemical studies indicate that this complex is among the most efficient homogeneous catalysts for water reduction, with a turnover frequency of 917.7 mol of hydrogen per mole of catalyst per hour at an overpotential of 636.7 mV (pH 7.0). Additionally, under photoirradiation with blue light (λ _max = 469 nm), complex 1 in combination with [Ru(bpy)₃]Cl₂ and ascorbic acid (pH 4.0 in aqueous solution) also produces hydrogen with a turnover number of 4.9 × 10⁵ mol of H₂ per mol of catalyst.     

Synthesis,crystal structures and magnetic properties of a radical ligand and its corresponding copper(II) complex

A new chelating radical ligand, IMMeBzIm (IMMeBzIm = 2-{2′-[(l′-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl) and its copper(II) complex [Cu(IMMeBzIm)₂(ClO₄)]·(ClO₄) have been prepared and characterized by IR, magnetic and single-crystal X-ray analysis. In the crystal structures, both free IMMeBzIm and the complex crystallize in monoclinic space groups P2(1)/c and C2/c, respectively. The structure of IMMeBzIm consists of mononuclear molecules. In the complex, the coordination geometry around copper is a distorted square pyramid, and the apical position is occupied by one oxygen atom of ClO₄ ⁻ anion. A 1-D polymer is formed through intermolecular H-bond interactions. The variable-temperature magnetic susceptibility of the free IMMeBzIm suggests weak antiferromagnetic coupling with J = −1.12 cm⁻¹ where the spin Hamitonian is defined as Ĥ = −2 JŜ ₁ Ŝ ₂ between radical and radical.     

Synthesis,characterization, and catalytic application of a zinc(II) complex bearing a pyrazole-based ligand

The reaction between ZnCl₂ and N,N-bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-1-phenylethylamine (bdmppea) affords [(bdmppea)ZnCl₂], whose structure has been determined by X-ray crystallography. The [(bdmppea)ZnEt₂] complex in situ prepared by the reaction between [bdmppea] and ZnEt₂ exhibited high activity toward the polymerization reaction of rac-lactide at room temperature. However, its activity decreased sharply with decreasing temperature. Stereospecificity of this catalyst characterized by heterotacticity (P_r) was determined by homonuclear decoupled NMR spectroscopy, which value was ∼0.58.     

Synthesis,characterization, DNA binding properties,and biological activities of a mixed ligand copper(II) complex of ofloxacin

A mixed ligand coordination compound of copper with ofloxacin (oflo) and phenanthroline (phen) has been synthesized and characterized by means of X-ray single crystal diffraction and spectroscopic methods. Structural features of the coordination compound are described. CD and CV studies of the interactions of the title complex with calf thymus DNA (CT-DNA) show that the complex can bind to CT-DNA by intercalation and electrostatic binding modes. Antibacterial activities of the title compound, a Cu–oflo complex reported earlier and free oflo have been studied against different microorganisms. Both copper complexes enhance the antibacterial activities of the quinolone drugs. The inhibitory effect of the three compounds on two cancer cell lines was measured and the results indicate that the title complex has strongest inhibitory effect.     

Cobalt(II), nickel(II) and copper(II) complexes of a Schiff base ligand: synthesis,structural characterization and luminescence properties

A Schiff base ligand (HL), 2,4-dimethoxy-N-(5-chloro-2-hydroxybenzylidene)-benzenamine, derived from 5-chloro-2-hydroxybenzaldehyde and 2,4-dimethoxyaniline, and its metal complexes [Co(L)₂]·CH₃OH (1), [Ni(L)₂] (2), [Cu(L)₂] (3) have been synthesized. The compounds were characterized by analytical and spectroscopic methods. In addition, the structures of the Schiff base HL and its Co(II) complex were determined by single-crystal X-ray analysis. The Co(II) center is six-coordinate, being coordinated to two imine nitrogen, two phenolate oxygen and two methoxy oxygen atoms of two crystallographically independent Schiff base ligands. Luminescence properties of HL and its complexes were investigated both in solution and in the solid state.     

Synthesis in solvent-free conditions,characterization and biological activity of a new Schiff-base ligand and its Cu(II) complex

A new bis-imine Schiff base (N₈O₂ donor, LH₂) has been synthesized by melt condensation of 3-amino-1,2,4-triazole with 1,5-bis(2′-formylphenyl)-1,5-dioksapentane in 2 : 1 molar ratio, in solvent and solvent-free conditions. The ligand has been characterized using FTIR, UV–Vis, ¹H NMR, ¹³C NMR, mass spectra, elemental analysis, and thermal (TGA-DSC) techniques. A new complex of LH₂ with Cu(II) has been synthesized in solvent and solvent-free conditions. FTIR, UV–Vis mass spectra, and thermal analysis (TGA-DSC) have been used to characterize the Cu(II) complex. Thermal degradation showed that the final products were black carbon and metallic copper. Distorted octahedral geometry has been observed around CuLH₂Cl₂ · LH₂ and its Cu(II) complex have been screened for in vitro antifungal and antioxidant activities. Antioxidation was determined for their superoxide scavenging and reducing activities. The ligand and its Cu(II) complex have strong antifungal activity against Aspergillus niger. The compounds have significant superoxide anion radical scavenging activity and reducing power against various antioxidant systems in vitro.     

Synthesis,characterization, and catalytic activity of a polymer-supported copper(II) complex with a thiosemicarbazone ligand

A thiosemicarbazone Cu(II) complex anchored to a polystyrene framework has been synthesized and characterized by analytical and spectroscopic techniques. The complex was found to be a highly active catalyst for the oxidation of various organic substrates including alkenes and alcohols using H₂O₂ as oxidant. The reaction conditions were optimized with respect to temperature, solvent, oxidant, catalyst amount, and substrate to peroxide ratio. The heterogeneous catalyst was reused five times without significant loss of activity. A comparison between the catalytic activities of this polymer-supported Cu(II) complex and its homogeneous analogue was carried out.     

Synthesis, experimental and theoretical characterization of N,N'-dipyridoxyl (1,4-butanediamine) Schiff-base ligand and its Cu(II) complex

A new N,N'-dipyridoxyl(1,4-butanediamine) [=H(2)BS] Schiff-base ligand and its Cu(II) salen complex, [Cu(BS)(H(2)O)(CH(3)OH)], were synthesized and characterized by IR, UV-vis, (1)H NMR, mass spectrometry and elemental analysis. Also, full optimization of the geometries, (1)H NMR chemical shifts (for the H(2)BS) and vibrational frequencies were calculated by using density functional theory (DFT) method. Structure of the H(2)BS ligand is not planar, i.e. two pyridine rings are not in the same plane. In the structure of the Cu complex, the Schiff-base ligand acts as a dianionic tetradentate ligand in N, N, O(-), O(-) manner. The coordinating atoms of BS(2-) occupy equatorial positions of the octahedral complex, where the H(2)O and CH(3)OH ligands locate at axial positions. The calculated results are in good agreement with the experimental data, confirming the suitability of the proposed and optimized structures for the H(2)BS ligand and its Cu complex.     

Synthesis and characterization of a photochromic magnesium(II) coordination polymer based on a naphthalene diimide ligand

Naphthalene diimides, which are planar, chemically robust and redox‐active, are an attractive class of electron‐deficient dyes, which can undergo a single reversible one‐electron reduction to form stable radical anions in the presence of electron donors upon irradiation. This makes them excellent candidates for organic linkers in the construction of photochromic coordination polymers. Such a photochromic one‐dimensional linear coordination polymer has been prepared using N ,N ′‐bis(3‐carboxyphenyl)naphthalene‐1,8:4,5‐tetracarboximide (H₂BBNDI). Crystallization of H₂BBNDI with magnesium nitrate in an N ,N ′‐dimethylformamide (DMF)/ethanol/H₂O mixed‐solvent system under solvothermal conditions afforded the one‐dimensional coordination polymer catena‐poly[[bis(dimethylformamide‐κO )magnesium(II)]‐bis[μ‐N‐(3‐carboxylatophenyl)‐N ′‐(3‐carboxylphenyl)naphthalene‐1,8:4,5‐tetracarboximide‐κ²O :O ′]], [Mg(C₂₈H₁₃N₂O₈)₂(C₃H₇NO)₂]_n . The asymmetric unit contains half of a magnesium cation, one HBBNDI⁻ ligand and one DMF molecule. Two partially deprotonated HBBNDI⁻ ligands bridge two magnesium cations to form a one‐dimensional chain. Strong inter‐chain π–π interactions between the naphthalene rings of the HBBNDI⁻ ligand and the imide rings of adjacent chains provide a two‐dimensional structure. The supramolecular three‐dimensional framework is stabilized by π–π interactions between naphthalene rings of neighbouring two‐dimensional supramolecular networks. The complex exhibits a reversible photochromic behaviour, which may originate from the photoinduced electron‐transfer generation of radicals in the HBBNDI⁻ ligand.     

Synthesis,characterization, luminescence,antibacterial, and catalytic activities of a palladium(II) complex involving a Schiff base

A new Pd(II) complex of fluorine-containing Schiff base ligand, [Pd₂(L)₂Cl₂] (1) [L?=?N-(4-fluorobenzylidene)-2,6-diethylbenzenamine], has been synthesized using solvothermal method and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, UV–vis absorption spectra, and single-crystal X-ray diffraction. Complex 1 is a μ-chloro-bridged dinuclear cyclometallated Pd(II) complex. Thermal analysis indicates that 1 is quite stable to heat. 1 exhibits quadruple emissions in the solid state (λ _max?=?766?nm) and possesses fluorescence lifetimes (τ ₁?=?87.20?ns, τ ₂?=?190.45?ns, and τ ₃?=?1805.10?ns at 616?nm); broad structureless bands at 690–800?nm are tentatively assigned to an excimeric ³IL transition. The Schiff base (L) and its palladium(II) compound (1) have been screened for their antibacterial activity against several bacteria, and the results are compared with the activity of penicillin. Moreover, 1 has been shown to be highly effective in the Heck reaction of 4-bromotoluene with acrylic acid.     

Synthesis,characterization, structure and magnetic properties of azido-bridged nickel(II) and copper(II) complexes with a pyridylpyrazole-based ligand

A new pyridylpyrazole-containing tetradentate ligand, namely N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)aminomethylpyridine (L), and two of its binuclear azido-bridged complexes, [Ni₂(L)₂(N₃)₂](ClO₄)₂·2EtOH (1) and [Cu₂(L)₂(N₃)₂](ClO₄)₂ (2), have been synthesized and characterized by physico-chemical and spectroscopic methods. The crystal structures of both complexes are reported. Each metal atom in the complexes has a MN₆ coordination environment with distorted octahedral geometry. Variable-temperature magnetic susceptibility measurements for complex (1) show typical antiferromagnetic behavior with J value −84.5 ± 1.3 cm⁻¹, whereas complex (2) has no magnetic interactions.     

New mixed ligand complexes of ruthenium(II) that incorporate a modified phenanthroline ligand: Synthesis, spectral characterization and DNA binding

The hexafluorophosphate and chloride salts of two ruthenium(II) complexes, viz. [Ru(phen)(ptzo)₂]² and [Ru(ptzo)₃]²⁺, where ptzo = 1,10-phenanthrolino[5,6-e]1,2,4-triazine-3-one (ptzo) — a new modified phenanthroline (phen) ligand, have been synthesised. These complexes have been characterised by infrared, UV-Vis, steady-state emission and¹H NMR spectroscopic methods. Results of absorption and fluorescence titration as well as thermal denaturation studies reveal that both thebis- and tris-complexes of ptzo show moderately strong affinity for binding with calf thymus (CT) DNA with the binding constants being close to 10⁵M^-1 in each case. An intercalative mode of DNA binding has been suggested for both the complexes. Emission studies carried out in non-aqueous solvents and in aqueous media without DNA reveal that both [Ru(phen)(ptzo)₂]²⁺ and [Ru(ptzo)₃]²⁺ are weakly luminescent under these solution conditions. Successive addition of CT DNA to buffered aqueous solutions containing [Ru(phen)(ptzo)₂]²⁺results in an enhancement of the emission. These results have been discussed in the light of the dependence of the structure-specific deactivation processes of the MLCT state of the metallo-intercalator with the characteristic features of its DNA interaction. In doing so, attempts have been made to compare and contrast its properties with those of the analogous phenanthroline-based complexes including the ones reported by us previously.     

Synthesis, characterization, luminescence and nonlinear optical (NLO) properties of truxene-containing platinum(II) alkynyl complexes

A series of luminescent trinuclear platinum(II) alkynyl complexes containing dihydro-5H-diindeno[1,2-a;1′,2′-c]fluorene (truxene) as the core and aryl alkynyl ligands with different electronic properties at the periphery has been successfully synthesized and characterized. The electronic absorption, emission, nanosecond transient absorption and electrochemical properties of these complexes have been reported. These complexes showed long-lived emissions in degassed benzene solution at room temperature, and their emissions have been assigned to originate from triplet states of intraligand (IL) character with some mixing of metal-to-ligand charge-transfer (MLCT) character. The luminescent platinum(II) alkynyl complexes are found to show two-photon absorption (2PA) and two-photon induced luminescence (TPIL) properties, and their two-photon absorption cross-sections have been determined to be 6-51 GM upon excitation at 720 nm.     

Synthesis,structure, and biological properties of a Co(II) complex with tridentate Schiff base ligand

A new Co(II) complex of general formula [Co(L)₂] has been synthesized from a NNO tridentate Schiff base ligand, 2-[(piperidin-2-ylmethylimino)-methyl]-phenol (L). The title complex is characterized by elemental, spectroscopic, antibacterial, and single crystal X-ray structural studies. X-Ray crystallography reveals that the complex shows a distorted octahedral geometry around the Co(II) ion. The complex was tested against several bacteria and shows good antibacterial activities against almost all of the bacteria. The interactions of the title complex with calf thymus deoxyribonucleic acid (CT-DNA) have been investigated by electronic absorption and fluorescence spectroscopy, showing that the complex interacts with CT-DNA via partial intercalation. Thermogravimetric analysis (TGA) of the complex has also been reported and the result shows that the complex is thermally stable up to 134 °C.     

Synthesis and characterization of a Zn(II) complex of a pyrazole-based ligand bearing a chiral l-alaninemethylester

Reaction of ZnCl₂ with a new ligand N,N-bis(3,5-dimethylpyrazolylmethyl)-l-alaninemethylester (bdmpame) in methanol gives [ZnCl₂(bdmpame)]. The structure of [ZnCl₂(bdmpame)]·CH₂Cl₂ has been resolved by X-ray crystallographic analysis. The Zn atom has a distorted tetrahedral geometry involving a nitrogen atom from each pyrazole in bdmpame and two chloro ligands with bond lengths in the range 2.037(4)–2.237(2) Å. The nitrogen atom of the l-alaninemethylester group in the compound was not coordinated to the metal center, giving an eight-membered ring in which the nitrogen atoms of each pyrazole in bdmpame are coordinated to the metal center. The results of the catalytic enantioselective reduction of acetophenone promoted by ligand/Zn(OTf)₂=1:1 mole ratio in the presence of catecholborane for 48 h at 0°C gives (S)-(−)-1-phenylethanol in 21% ee with 68% yield.     

Synthesis,crystal structures,antibacterial activities,and fluorescence properties of Schiff base ligand and its nickel(II) complex

A complex [Ni(L · CH₃OH)₂] · CH₃OH was synthesized, in which a Schiff base ligand HL · CH₃OH, was derived from condensation of 1-phenyl-3-methyl-4-(p-methylbenzoyl)-5-pyrazolone with L-Valine methyl ester. They were characterized by IR and single crystal X-ray diffraction. The ligand contains three independent molecules L · CH₃OH. The complex has a dissociative methanol and nickel six-coordinated compound. Every fragment is a distorted octahedron with four oxygen atoms and two nitrogen atoms. The HL · CH₃OH ligand and its complex have been tested in vitro to evaluate their antibacterial activity against bacteria Escherichia coli and Bacillus subtilis. It has been found that the complex has higher activity than the corresponding free ligand HL · CH₃OH against the same bacteria. The HL · CH₃OH ligand and its complex have been tested by liquid fluorescent. It has been found that the complex has higher fluorescence property than ligand.     

Synthesis,characterization, and antimicrobial properties of two Cu(II) complexes derived from a benzimidazole ligand

Two copper(II) complexes, [Cu(L)₂](ClO₄)₂] and [Cu(L)(bipy)](ClO₄)₂, were prepared and characterized by the spectroscopic and analytic methods, where L is N-butylbenzimidazole and bipy is 2,2′-bipyridine. Single crystals of [Cu(L)(bipy)](ClO₄)₂ suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a DMF solution of the complex and the complex was found to crystallize as [Cu(L)(bipy)](ClO₄)₂·DMF. The asymmetric unit contains one [Cu(L)(bipy)]²⁺, two uncoordinated perchlorates, and one DMF solvate. Coordination geometry around Cu(II) is distorted square pyramidal with τ value of 0.31. Thermal properties of the complexes were examined by thermogravimetric analysis, indicating that the complexes are thermally stable to 310?°C. The metal complexes were screened for their in vitro antibacterial and antifungal activities Bacillus subtilis and Bacillus cereus (as Gram(+) bacteria), Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae (as Gram(–) bacteria), and Saccharomyces cerevisiae, Candida utilis, and Candida albicans (as yeasts). The complexes show antibacterial and antifungal activities against bacteria and yeasts.