Single Crystal X-ray Determination Research Articles

Synthesis, characterization, crystal structures and biological activity of novel NiII2ZnII2 complexes derived from 2-(3-ethoxy-2-hydroxybenzylideneamino)-4-methylphenol

Molecular nanoclusters comprising heterometallic Ni-Zn cores are an interesting class of compounds. In this paper, five novel NiII-ZnII complexes [Ni2Zn2ClL3(HL)3]·0·.25H2O (1), [Ni2Zn2BrL3(HL)3]·0·.25H2O (2), [Ni2Zn2Br2L2(N3)2(MeOH)2]·2MeOH (3), [Ni2Zn2I2L2(N3)2(MeOH)2]·2MeOH (4), and [Ni2Zn2I2L2(N3)2(DMF)2] (5), were prepared from the Schiff base 2-(3-ethoxy-2-hydroxybenzylideneamino)-4-methylphenol (H2L). The complexes have been characterized by elemental analysis, IR, UV–Vis spectra. Molecular structures of the complexes have been determined by single crystal X-ray determination. In complexes 1 and 2, three of the Schiff bases coordinate to the metal atoms via ether oxygen, imino nitrogen and two phenolate oxygen atoms, while the fourth one coordinates through ether oxygen, imino nitrogen and one phenolate oxygen atoms. In complexes 3, 4 and 5, all the donor atoms in the Schiff base ligands participate in coordination. The Ni and Zn atoms in the complexes are in octahedral and trigonal bipyramidal coordination, respectively. The anions of the metal salts and the azide anion, as well as methanol and DMF molecules furnish the coordination sphere. The compounds were evaluated for their antibacterial activities on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens, and antifungal activities on Candida albicans and Aspergillus niger. Interestingly, the complexes have effective activities against Bacillus subtilis and Staphylococcus aureus.

Synthesis, characterization, crystal structures and biological activity of 4-chloro-2-(2-hydroxy-3-ethoxybenzylideneamino)phenol and complexes

Molecular nanoclusters comprising a heterometallic 3d-4f stoichiometry are an interesting class of compounds. In this paper, a chloro-containing Schiff base 4-chloro-2-(2-hydroxy-3-ethoxybenzylideneamino)phenol (H2L) was prepared by condensation reaction of 3-ethoxysalicylaldehyde with 2-amino-4-chlorophenol in methanol. The Schiff base is predisposed to chelate within a cluster core both 3d and 4f metal ions. Reaction of H2L with nickel salts afforded a tetranuclear NiII complex [Ni4L4(MeOH)4] (1), while with nickel salts and lanthanide(III) nitrate three tetranuclear NiII-LnIII complexes [Ni2Eu2L4(NO3)2(DMF)2] (2), [Ni2Er2L4(NO3)2(DMF)2] (3), [Ni2Tb2L4(CH3COO)2(DMF)2]·4DMF (4) were obtained. H2L and the complexes have been characterized by elemental analysis, IR, UV–Vis spectra. H2L has also been characterized by 1H and 13C NMR spectra. Molecular structures of the compounds have been determined by single crystal X-ray determination. In the complexes, the Schiff base ligands coordinate to the metal atoms via ether oxygen, imino nitrogen and two phenolate oxygen atoms. All the Ni atoms in the complexes are in octahedral coordination. The rare earth metal atoms are eight coordinated by the phenolate and ether oxygen of the Schiff base ligands, and anionic and solvent oxygen atoms, forming square antiprismatic coordination. The compounds were evaluated for their antibacterial activities on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens, and antifungal activities on Candida albicans and Aspergillus niger, and gave interesting results.

Synthesis, Crystal Structures and Antibacterial Activity of Nickel(II) and Copper(II) Complexes Derived from (E)-2-((2,3-dihydrobenzo[b][1,4]dioxin-6-yl)methylene)- N-phenylhydrazinecarbothioamide

The biosynthesis of fatty acids is essential for the survival of bacteria, and β-ketoacyl-acyl carrier protein synthase III (FabH) is a promising target for antibacterial drug development. Nickel(II) complex [NiL2] (1) and copper(II) complex [CuL2] (2), where L is (E)-2-((2,3-dihydrobenzo[b][1,4]dioxin-6-yl)methylene)-N-phenylhydrazinecarbothioamide, were synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy and HRMS. Structures of the complexes were further studied by single crystal X-ray determination, which reveals that the nickel and copper atoms in the complexes are in tetrahedral geometry. These compounds were evaluated for their antibacterial and E. coli FabH inhibitory activities.

Syntheses, Crystal Structures and Antimicrobial Activity of Zinc(II) Complexes Derived from 5-Bromo-2- (((2-piperazin-1-yl)ethyl)imino)methyl)phenol

Three new zinc(II) complexes, [ZnCl2L]·CH3OH (1), [ZnClL(NCS)]·2CH3OH·0.5H2O (2), and [ZnL(NCS)2]·CH3OH·H2O (3), where L is the zwitterionic form of 5-bromo-2-(((2-piperazin-1-yl)ethyl)imino)methyl)phenol, NCS is thiocyanate anion, were facile prepared by reaction of different molar ratio of L, zinc chloride and ammonium thiocyanate in methanol. The complexes were characterized by IR and UV-Vis spectroscopy. Detailed structures of the three complexes were confirmed by single crystal X-ray determination. The Zn atoms in the complexes are in tetrahedral coordination. The Schiff base ligand coordinates to Zn atom through phenolate oxygen atom and amino and imino nitrogen atoms. The remaining two sites are occupied by two Cl for 1, one Cl and one NCS for 2, and two NCS for 3. The compounds show significant antimicrobial activities.

Alkyl chain length influence of the functionalized diethanolamine ligand on the slow relaxation of the magnetization in {CoIII3DyIII3} complexes.

We report the synthesis, structural characterization and magnetic properties of a series of Co(III)/Dy(III) complexes built up from an N-alkyl derivatized amino-alcohol ligand diethanolamine, functionalized with CnH2n+1 alkyl chains (n = 3, 4, 6, 8 and 10). While n = 3 afforded a butterfly {CoIII2DyIII2} core, the other alkyl chains (n = 4, 6, 8) afforded hexanuclear triangle-in-triangle {CoIII3DyIII3} complexes as shown by single-crystal X-ray determinations. Infrared spectroscopy allows us to characterize the C10 derivative complex, which did not crystallize. Magnetic ac susceptibility data collected below 10 K at driving frequencies up to 10 kHz under zero-dc field and up to 1 T provide insight into the SMM behaviour of the studied complexes. The characteristic time of the magnetization dynamics can be understood in terms of the competing Raman, Direct and Orbach-like mechanisms. A relationship between the magnetization dynamics within the family of complexes and the increasing alkyl chain length is discussed.

Synthesis, Characterization and X-Ray Crystal Structures of Oxidovanadium(V) Complexes Derived from N'-(2-Hydroxy-5-methylbenzylidene)-4-methylbenzohydrazide with Antibacterial Activity.

A dinuclear oxidovanadium(V) complex [V2O2L2(OMe)2] (1) was synthesized from N'-(2-hydroxy-5-methylbenzylidene)-4-methylbenzohydrazide (H2L) and VO(acac)2 in MeOH. Reaction of complex 1 with 3-hydroxy-2-methyl-4-pyrone (HL') afforded a mononuclear oxidovanadium(V) complex [VOLL'] (2). The hydrazone and both complexes were characterized by IR, UV and 1H NMR spectroscopy, as well as X-ray single crystal determination. X-ray powder diffraction of the complexes was performed. The V atoms in the two complexes are in octahedral coordination. The molecules of complex 2 are linked through non-classical hydrogen bonds of type C-H∙∙∙O to form one-dimensional chains running along the a axis. The biological assay indicates that the complexes have good antimicrobial activities on the bacteria strains P. aeroginosa, S. aureus, B. subtilis and E. coli.

Syntheses, Characterization, Crystal Structures and Xanthine Oxidase Inhibitory Activity of Hydrazones.

Four new fluoro-containing hydrazones were synthesized from 4-fluorobenzaldehyde with chloro- and nitro-substituted benzohydrazides. They are 3-chloro-N'-(4-fluorobenzylidene)benzohydrazide (1), 2-chloro-N'-(4-fluorobenzylidene)benzohydrazide (2), N'-(4-fluorobenzylidene)-4-nitrobenzohydrazide (3), and N'-(4-fluorobenzylidene)-3-nitrobenzohydrazide (4). The compounds have been characterized by IR and 1H NMR spectra, as well as X-ray single crystal determination. Xanthine oxidase (XO) inhibitory activity indicated that the nitro substituted compounds 3 and 4 have effective activity. Docking simulation was performed to insert the compounds into the crystal structure of xanthine oxidase at the active site to investigate the probable binding modes.

Ethanol-Coordinated Dioxidomolybdenum(VI) Complexes with Aroylhyrazone Ligands: Synthesis, Spectroscopic Characterization, Crystal structures and Catalytic Oxidation Property

Two new dioxidomolybdenum(VI) complexes, [MoO2L1(EtOH)] (1) and [MoO2L2(EtOH)] (2), derived from the aroylhydrazone ligands N’-(2-hydroxyl-3-methoxybenzylidene)-3-methylbenzohydrazide (H2L1) and 4-fluoro-N’-(2-hydroxylbenzylidene) benzohydrazide (H2L2), respectively, were prepared in ethanol under ambient temperature. Both complexes were characterized by elemental analysis, IR and UV-Vis spectroscopy, as well as single crystal X-ray determination. The Mo atoms in the complexes are in octahedral coordination. Crystal structures of the complexes are stabilized by hydrogen bonds. The catalytic property for epoxidation of styrene by both complexes was studied.

Syntheses, Crystal Structures and Antimicrobial Activity of Copper(II) Complexes with the Ligand N,N’-Bis(4-bromosalicylidene)propane-1,2-diamine

Two new copper(II) complexes, [CuL] (1) and [Cu4Cl2L2(N3)2]·CH3OH (2), derived from the bis-Schiff base N,N’-bis(4-bromosalicylidene)propane-1,2-diamine (H2L) have been prepared and characterized by spectroscopy methods, as well as single crystal X-ray determination. The Cu atom in the mononuclear complex 1 is in square planar coordination. The outer and inner Cu atoms in the phenolate and azide co-bridged tetranuclear complex 2 are in square planar and square pyramidal coordination, respectively. The antibacterial activities of the Schiff base and the two copper complexes have been assayed on the bacteria Staphylococcus aureus and Escherichia coli, and the yeast Candida parapsilosis.

Microwave-Assisted Synthesis, Characterization, Crystal Structures and Antibacterial Activities of Zinc Complexes Derived from 5–Bromo-2-((cyclohexylimino)methyl)phenol

A dinuclear zinc complex [Zn2L2] (1), and four mononuclear zinc complexes [ZnBr2(LH)2] (2), [ZnCl2(LH)2] (3), [Zn(LH)2(NCS)2] (4) and [ZnI(CH3OH)L] (5), have been prepared from the Schiff base 5-bromo-2-((cyclohexylimino) methyl)phenol (HL) by microwave irradiation method. All the zinc complexes were characterized by CHN elemental analyses, infrared and electronic spectra. Structures of the complexes were further studied by single crystal X-ray determination, which reveals that all the zinc atoms in the complexes are in tetrahedral geometry. The halide and pseudohalide anions are preferred co-ligands in the preparation of such complexes with binary ligands. The biological activity of the complexes on the bacterial strains Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli was evaluated. The complexes bearing halide and pseudohalide ligands show effective activities on the bacteria strains.

Synthesis, crystal structure, DNA and protein binding study of N-(4-pyridyl)-1,8-naphthalimide copper(II) complex

We have designed and synthesized 1,8-naphthalimide-based ligand N-(4-pyridyl)-1,8-naphthalimide (L) and its mixed ligand complex 1 [Cu(phen)2(L)](ClO4)2, where L = N-(4-pyridyl)-1,8-naphthalimide; phen=,10-phenanthroline. The synthesized copper complex has been structurally characterized with a single crystal X-ray determination study. The coordination geometry around the complex 1 is found to be distorted square pyramidal with N5 donor sites. The CT-DNA (calf thymus DNA) binding ability of the complex has been studied with various spectroscopic techniques such as UV–Vis and fluorescence spectroscopy. The viscosity measurements and circular dichroism (CD) spectral studies were also been studied to determine the CT-DNA binding mode. All the above studies indicate the groove binding mode of complex 1 to the CT-DNA. The interaction of bovine serum albumin (BSA) to the copper complex was investigated using fluorescence spectral studies and it is found to follow a dynamic quenching mechanism.

Synthesis, crystal structures, photophysical and antibacterial properties of Ag(I) and Zn(II) coordination polymers based on a flexible bisacylhydrazone ligand

A flexible bisacylhydrazone ligand (H4L) was designed and synthesized from the condensation reaction of dialdehyde 3,3′-thiobis(methyiene)-bis-(5-methyl-salicylaldehyde) (b) with isonicotinic hydrazide. In the DMSO/methanol solution, two coordination polymers (CPs), formulated as {[Ag(H4L)NO3]·DMSO·2H2O}n (CP 1) and {[Zn2(H2L2-)2]·3DMSO·3H2O}n (CP 2), were synthesized from H4L with Ag(I) or Zn(II) ions, respectively. These two CPs were characterized via elemental analysis, FT-IR spectra, and single crystal X-ray determination. The results show that CP 1 exists as a 1D looped-chain polymer, while CP 2 exists as a 2D sheet polymer. The coordination configurations of the two CPs were analyzed and compared in detail, which disclose the terminal pyridyl nitrogen atoms exhibit obviously stronger coordination ability compared to other sites. In addition, photophysical, electrochemical and antibacterial properties of H4L and the two CPs were investigated.

Syntheses, Crystal Structures and Xanthine Oxidase Inhibitory Activity of Aroylhydrazones.

A series of hydrazones, (E)-N'-(4-hydroxy-3-methoxybenzylidene)-4-nitrobenzohydrazide (1), (E)-4-(dimethylamino)-N'-(4-hydroxy-3-methoxybenzylidene)benzohydrazide (2), N'-(2-hydroxy-5-methylbenzylidene)-4-nitrobenzohydrazide (3) and 2-fluoro-N'-(2-hydroxy-5-methylbenzylidene)benzohydrazide (4), were prepared and structurally characterized by elemental analysis, IR and 1H NMR spectra, and X-ray single crystal determination. The xanthine oxidase inhibitory activities of the compounds were investigated. Among the compounds, N'-(3-methoxybenzylidene)-4-nitrobenzohydrazide (1) showed the strongest activity. Docking simulations were performed to insert the compounds into the crystal structure of xanthine oxidase at the active site and to investigate the probable binding modes.

Synthesis, characterization and X-ray crystal structures of oxidovanadium(V) and dioxidomolybdenum(VI) complexes derived from 2-bromo-N'-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide

A new oxidovanadium(V) complex, [VOL(OEt)(EtOH)] (1), and a new dioxidomolybdenum(VI) complex, [MoO2L(OH2)] (2), where L is the dianionic form of 2-bromo-N'-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide, have been synthesized and structurally characterized by physico-chemical methods and single crystal X-ray determination. X-ray analysis indicates that the V and Mo ions in the complexes are in octahedral coordination. Crystal structures of the complexes are stabilized by hydrogen bonds. The catalytic property for epoxidation of styrene by the complexes was evaluated. Both complexes have effective catalytic properties for the epoxidation of styrene, with conversions over 76% and selectivities over 92%.

Synthesis, Biological Evaluation, and Molecular Docking Studies of Hydrazones as Novel Xanthine Oxidase Inhibitors.

A series of hydrazones, 2-cyano-N'-(4-diethylamino-2-hydroxybenzylidene)acetohydrazide (1), N'-(5-bromo-2-hydroxy-3-methoxybenzylidene)-3-chlorobenzohydrazide monohydrate (2·H2O), N'-(2-hydroxy-3-methylbenzylidene)-4-nitrobenzohydrazide (3), and N'-(2-hydroxy-3-trifluoromethoxybenzylidene)-4-nitrobenzohydrazide (4), were prepared and structurally characterized by elemental analysis, IR and 1H NMR spectra, and single crystal X-ray determination. Xanthine oxidase inhibitory activities of the compounds were studied. Among the compounds, 2-cyano-N'-(4-diethylamino-2-hydroxybenzylidene)acetohydrazide shows the most effective activity. Docking simulation was performed to insert the compounds into the crystal structure of xanthine oxidase at the active site to investigate the probable binding modes.

Two Oxidovanadium(V) Complexes with Hydrazone Ligands: Synthesis, Crystal Structures and Catalytic Oxidation Property.

Two new oxidovanadium(V) complexes, [VOL1(aha)]DMF (1) and [VOL2(mat)] (2), where L1 and L2 are the dianionic form of N'-(4-bromo-2-hydroxybenzylidene)-3-methyl-4-nitrobenzohydrazide and N'-(3,5-dibromo-2-hydroxybenzylidene)pivalohydrazide, respectively, and aha and mat are the monoanionic form of acetohydroxamic acid and maltol, respectively, have been synthesized and structurally characterized by physico-chemical methods and single crystal X-ray determination. X-ray analysis indicates that the V atoms in the complexes are in octahedral coordination. Crystal structures of the complexes are stabilized by hydrogen bonds. The catalytic property for epoxidation of styrene by the complexes was evaluated.

Solvent-induced synthesis and crystal structures of copper(II) complexes derived from 4-chloro-2-[(2-hydroxymethylphenylimino)methyl]phenol with antibacterial activity

Two new polynuclear copper(II) complexes, [Cu2L2] (1) and [Cu4L4]CH2Cl2 (2), where L is 4-chloro-2-[(2-hydroxymethylphenylimino)methyl]phenolate, were synthesized and characterized by IR and UV–Vis spectroscopy. The molecular structures of the complexes were confirmed by single-crystal X-ray determination. The Cu ions in dinuclear complex 1 are in square planar coordination, while those in tetranuclear complex 2 are in square pyramidal coordination. The solvents used in the synthesis and crystallization play an important role for the formation of the final structures of the complexes. The Schiff base and two copper complexes were assayed for antibacterial activities by the MTT method.

P-Block metal complexes with bis(pyrazol-1-yl)acetato ligands.

The hetereoscorpionate ligands bis(pyrazol-1-yl)acetic acid (Hbpza) and bis(3,5-dimethylpyrazol-1-yl)acetic acid (Hbdmpza) are reacted with [Sn(OAc)2] or [Sn(acac)2] to yield the corresponding Sn(II) complexes. A single crystal X-ray determination for the in solution monomeric complex [Sn(bpza)2] (1a) revealed a dinuclear molecular structure [Sn2(bpza)4] (1b), with κ3-N,N,O-coordinated bpza ligands at each of the Sn(II) and two bpza ligands μ-bridging between the Sn(II) centres. The molecular structure of [Sn(bdmpza)2] (2) exhibits a homoleptic bisligand complex with both ligands displaced by the free electron pair, which is proven by DFT calculations. Oxidation of complex 2 in an attempt to synthesize a homoleptic Sn(IV) complex leads to the formation of [Sn(bdmpza)F3] (3). In addition, homoleptic bisligand gallium complexes [Ga(bdmpza)2][ClO4] (4) and [Ga(bpza)2][GaCl4] (5) were prepared and characterized by 71Ga NMR and IR spectroscopy as well as by X-ray crystallography.

Synthesis, Characterization, X-Ray Crystal Structures and Antibacterial Activity of Cobalt(III) Complexes Derived from 5-Bromo-2-((2-(phenylamino)ethylimino)methyl)phenol.

Two new and similar cobalt(III) complexes, [CoL2]·NO3 (1) and [CoL2]·Cl (2), where L is 5-bromo-2-((2-(phenylamino)ethylimino)methyl)phenolate, have been synthesized and characterized by IR and UV-Vis spectra. Structures of the complexes were confirmed by single crystal X-ray determination. The Co atoms in the complexes are in octahedral coordination, with the donor atoms come from the two Schiff base ligands, viz. phenolate oxygen, and imino and amino nitrogen. The anions of the cobalt salts crystallized as counteranions in the complexes. The complexes were assayed for antibacterial activities by MTT method.

N'-(Pyridin-3-ylmethylene)benzenesulfonohydrazide: Crystal structure, DFT, Hirshfeld surface and in silico anticancer studies

A new Schiff base, N'-(pyridin-3-ylmethylene)benzenesulfonohydrazide, was synthesized and characterized by elemental analysis, IR, Mass, 1H NMR and 13C NMR spectroscopy, and single-crystal X-ray determination. The asymmetric molecule crystallized in the monoclinic crystal system and P2(1)/c space group. Crystal data for C12H11N3O2S: a = 9.7547(4) Å, b = 9.8108(4) Å, c = 13.1130(5) Å, β = 109.038(2)°, V = 1186.29(8) Å3, Z = 4, μ(MoKα) = 0.270 mm-1, Dcalc = 1.463 g/cm3, 13338 reflections measured (5.296° ≤ 2Θ ≤ 55.484°), 2790 unique (Rint = 0.0494, Rsigma = 0.0400) which were used in all calculations. The final R1 was 0.0345 (I > 2σ(I)) and wR2 was 0.0914 (all data). In the crystal structure of the compound C12H11N3O2S, molecules are linked in a continuous chain by intermolecular of N∙∙∙HN=N hydrogen bonds. The pyridine moiety is planar, while the benzenesulfonohydrazide group adopts a gauche conformation about C-S-N angle (105.54°). The Hirshfeld surface analysis and fingerprint plots were used to establish the presence, nature, and percentage contribution of the different intermolecular interactions, including N-H∙∙∙N, C-H∙∙∙O, C-H∙∙∙C, and π∙∙∙π interactions, with the C-H contacts having the most significant contribution. The pairwise interaction energies were calculated at the B3LYP/6-31G(d,p) level of theory, and interaction energy profiles showed that the electrostatic forces had the most significant contribution to the total interaction energies of the different molecular pairs in the crystal. In-silico technique was used to examine the compound as a possible anticancer agent. The molecule demonstrated zero violation of the criteria of Lipinski’s rule of five with a polar surface area of 116.03 Å2. The molecule displayed favorable binding interactions with ten selected validated anticancer protein targets ranging from -9.58 to -11.95 kcal/mol and -2.73 to -5.73 kcal/mol on scoring and rescoring, respectively, with London dG and Affinity dG scoring functions. Two proteins; farnesyl transferase and signaling protein, preferred interactions with the Schiff-base over their co-crystallized inhibitors according to London dG scoring. Analysis of binding poses indicated that the Schiff-base made contact with amino acid residues of the two proteins through the N-H, sulphonyl oxygen, and phenyl groups, and this could be exploited in chemical and structural modification towards activity optimization.