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One mononuclear cobalt(II) compound of the type [Co(bnzd)2(NCS)2(OH2)2] (
1 ) (bnzd = benzidine) has been isolated through a single-pot reaction of the molecular building components in MeOH-H2O solvent mixture at room temperature and characterized by physico-chemical and spectroscopic methods. The crystal structure of complex1 has an octahedral geometry withtrans, trans, trans orientations in the order (N$^a$,N$^a$), (N$^t$,N$^t$), (O$^w$,O$^w$) [N$^a$ = N(amine), N$^t$ = N(thiocyanate) and O$^w$ = O(water)]. In crystalline state, individual units of1 are associated by weak cooperative O-H…N, O-H…S and N-H…S hydrogen bonds resulting in a 3D network structure. The compound is redox active and shows luminescence in MeOH solution. Thermal decomposition pattern of1 reveals the presence of two coordinated water molecules. Variabletemperature magnetic susceptibility measurement shows significant orbital contribution and numerical matrix diagonalization method gives the best fit parameters: 𝛼 = A∗k = 1.43; 𝜆 = −130 cm-1; 𝛥 = −864 cm-1; TIP = 0.000975; R = $1.19 \times 10^{−4}$. -
Synthesis and characterization of a mononuclear Fe(II) compound [Fe(L)](ClO4)2 (1) [L = N-(1-pyridin-2-yl-phenylidene)-N'-[2-({2-[(1-pyridin-2-ylphenylidene)amino]ethyl}amino)ethyl] ethane-1,2-diamine] (
1 ) is reported.1 crystallizes in P-1 space group with a = 11.9241(3) Å, b = 12.1994(3) Å and c = 13.0622(4) Å. The binding property of the complex with DNA has been investigated using absorption and emission studies, thermal melting, viscosity experiments and circular dichroism studies. The binding constant ($K_b$) and the linear Stern-Volmer quenching constant ($K_{\text{sv}}$) of the complex have been determined as $3.5 \times 10^3$M-1 and $2.73 \times 10^4$M-1, respectively. Spectroscopic and hydrodynamic investigations revealed intercalative mode of binding of1 with DNA.1 is also found to induce oxidative cleavage of the supercoiled pUC 18 DNA to its nicked circular form in a concentration dependent manner. -
Structural systematics of some metal complexes with 4,5-diazafluoren-9-one
Synthesis and X-ray structural characterization of three complexes of type
cis -[M(dafone)2(NCS)2] (M = Co(II),1 ; Ni(II),2 ; Zn(II),3 ; dafone = 4,5-diazafluoren-9-one) and a polymercis -[Cd(dafone)(NCS)2]$_n$ (4 ) have been reported. Each of the four complexes is crystallized in orthorhombic crystal system. Structural study reveals that each metal(II) centre in the four complexes adopts distorted octahedral geometry with MN6 chromophore in1-3 and MN4S2 chromophore in4 . The room temperature steady-state fluorescent intensity of dafone in dimethyl formamide at 402 nm is found to be quenched in these reported dafone complexes (1-4 ). -
A new nickel(II) complex [Ni(L)] (
1 ) [H2L = 1,1′-(1E,1′E)-(propane-1,3-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol] was synthesized and X-ray crystallographically characterized.1 crystallizes in orthorhombic crystal system with Cmc21 space group. The unit cell dimensions of the crystal are a = 30.6345(4)Å, b = 8.45340(10)Å, c = 7.75180(10)Å. Structural analysis reveals a tetradentate chelation behaviour of the dianionic ligand H2L having a distorted square planar geometry around Ni(II) with NiN2O2 chromophore in1 . The title complex1 behaves as an effective catalyst towards oxidation of 3,5-ditertiarybutyl catechol (3,5-DTBC) in acetonitrile to its corresponding quinone derivative in air. The reaction follows first-order reaction kinetics with rate constant 4.28 × 10−5 min-1. The reaction follows Michaelis-Menten enzymatic kinetics with a turnover number of ($K_{cat}$) 140.72 h-1 in acetonitrile. -
Two mononuclear compounds of the types pentacoordinated [Zn(L1)(OAc)]PF6·H2O (
1 ) and hexacoordinated [Zn(L2)(OAc)]PF6 (2 ) [L1 = N,N′-(bis(pyridin-2-yl)formylidene)-1,3-propanediamine; L2 = N,N′-(bis(pyridin-2-yl)benzylidene)-1,4-butanediamine] have been synthesized using one-pot reactions of a 1:1:1 molar ratio of Zn(OAc)2.2H2O, L1/L2, ammonium hexafluorophosphate in MeOH at room temperature. Compounds1 and2 are characterized on the basis of microanalytical, spectroscopic, thermal and other physicochemical results. Single crystal X-ray structural study reveals that the zinc(II) centre in1 is coordinated by four N atoms of the Schiff base L1 and one O atom of terminal acetate with a ZnN4O chromophore, whereas in2 , the zinc(II) centre is bound by four N atoms of the tailored Schiff base L2 and two O atoms of the chelated acetate. In the crystalline state, mononuclear units in1 are engaged in weak cooperative intermolecular O-H⋯O and C-H⋯F hydrogen bonds affording a 1D chain. The individual units of2 are packed by 𝜋 ⋯ 𝜋 and anion⋯ 𝜋 interactions to form a 2D sheet structure. The complexes show reasonable thermal stabilities and display intraligand 𝜋 $\to$ 𝜋∗ fluorescence in solid state at room temperature. -
DNA binding and cleavage activity of a structurally characterized Ni(II) Schiff base complex
Synthesis and characterization of a mononuclear Ni(II) compound [Ni(L)(H2O)2](NO3)2 [L = N,N'-bis((pyridine-2-yl)phenylidene)-1,3-diaminopropan-2-ol] (
1 ) is reported.1 crystallizes in triclinicP-1 space group with a = 8.1911(2) Å, b = 11.6624(3) Å, c = 16.5356(4) Å and𝛼 = 108.8120(10)° , 𝛽 = 91.2010(10)° , 𝛾 = 91.1500(10)° . The binding property of the complex with DNA has been investigated using absorption and emission studies, and viscosity experiment. The binding constant (Kb) and the linear Stern-Volmer quenching constant (Ksv) of the complex have been determined as 9.23 × 10 4 M−1 and 2.0 × 10 4 M−1, respectively. Spectroscopic and hydrodynamic investigations revealed groove or electrostatic nature of binding of1 with DNA.1 is also found to induce oxidative cleavage of the supercoiled pUC 18 DNA to its nicked circular form in a concentration dependent manner. -
One nickel(II)-dithiolene complex bis(1,2-diphenylethylene-1,2-dithiolate)nickel(II) has been synthesized and crystallographically characterized. The complex is square planar at its metal centre. The compound in its solid-state is found to conduct electricity at room temperature. Variation of conduction is also found on raising the temperature. Instead of a metal…metal orbital overlap, the electron density is expected here to pass through some other covalent and electrostatic bonds of the compound in solid-state resulting in electricity conduction.
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An unsymmetrical Schiff base 2-(1-(2-aminophenylimino)ethyl)phenol (LH3) and its trinuclearPd(II) complex [PdII3(LH)3] (1) were successfully synthesized and X-ray crystallographically characterized. 1 effectively catalyzed Suzuki-Miyaura coupling on reaction between each of bromobenzene and substituted bromobenzenes with phenylboronic acid resulting biphenyl and substituted biphenyls, respectively. The catalyzed products were characterized gas chromatographically.
An unsymmetrical Schiff base 2-(1-(2-aminophenylimino)ethyl)phenol (LH3) and its trinuclear Pd(II) complex [PdII3(LH)3] (1) were synthesized, and characterized both spectroscopically and X-ray crystallographically. LH3 and 1 were found to had Cc and P-1 space groups with monoclinic and triclinic crystal systems. 1 was found to catalyze Suzuki-Miyaura cross coupling reactions to produce biphenyl and p-nitrobipheenyl from respective bromobenzene and p-nitrobromobenzene.
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Two bis(dithiolene)nickel(II) complexes of the type [Ni(L)2] [L = 1,2-di(4-chlorophenyl)ethene-1,2-dithiolate (1) and 1,2-di(4-bromophenyl)ethene-1,2-dithiolate (2)] have been synthesized and characterizedby different chemical and physicochemical methods. 1 was characterized by different spectroscopic andspectrometric techniques. The molecular structure of 2 was derived from the single crystal X-ray diffraction.The electrochemical activities of both complexes were investigated by cyclic voltammetry. Both the complexeswere found to exhibit intense near-infra-red (NIR) absorptions.
Two isostructural bis(dithiolene)nickel(II) complexes of general formula [Ni(L)2] [L = 1,2-di(4-chlorophenyl)ethene-1,2-dithiolate (1) and 1,2-di(4-bromophenyl)ethene-1,2-dithiolate (2)] have been synthesized and characterized by different chemical and physicochemical methods. 2 was crystallized, and its molecular structure was derived from the single crystal X-ray diffraction. In spite of several efforts, crystallization of 1 was not possible. 1 was characterized by several spectroscopic and spectrometric methods. Redox activities of ligands of both complexes were investigated by cyclic voltammetry. Both the complexes were found to exhibit intense near-infra-red (NIR) absorptions.
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An ion-pair complex [Ni(
o -phen)3][Ni(L)2]2.CH2Cl2 (1) [L = 1,2-diphenylethylene-1,2-dithiolate,o -phen = 1,10-phenanthroline] has been synthesized and X-ray crystallographically characterized. The solution structure of 1, as derived from cyclic voltammetry, conforms well to the solid-state molecular structure. The redox peaks obtained from the electrochemical analysis of 1 are to some extent a combination of the peaks obtained individually for [Ni(o -phen)3]2+ and [Ni(L)2]. Moreover, the reaction protocol for the synthesis of the title complex by the addition of o-phen to [Ni(L)2] is analyzed electrochemically. 1 conducts electricity in solid-state. The electrical conductivity varied on varying temperatures from 308 K (35°C) to423 K (150°C). The compound is found to be thermally unstable after 150 °C.An ion-pair complex [Ni(
o -phen)3][Ni(L)2]2.CH2Cl2 (1) [L = 1,2-diphenylethylene-1,2-dithiolate] has been synthesized and characterized by X-ray crystallography. On electrochemical characterization in solution, the redox peaks (reduction) obtained from the cyclic voltammetry of 1 are found to be a combination of the peaks obtained individually for [Ni(o-phen)3]2+ and [Ni(L)2]. 1 also conducts electricity in a solid state like a semiconducting material.
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Journal of Chemical Sciences
Volume 135, 2023
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