2-benzoyl Pyridine Research Articles

Ruthenium(III) and (II) complexes containing pyridine moiety: Synthesis, crystal structure and in vitro biological evaluation

In the present study, reaction of tridentate chelating hydrazone Schiff base N'-(phenyl(pyridine-2-yl)methylidene)benzhydrazide (HL) with [RuIIICl3(PPh3)3] afforded ruthenium(III) and ruthenium(II) complexeswith the composition of [RuIII(L)Cl2(PPh3)] (1), [RuII(L)Cl(CO)(PPh3)] (2) and [RuII(Bp)Cl(CO)(PPh3)] (3) (where Bp= benzoyl pyridine) in one pot reaction. The molecular structures of synthesized complexes were examined by single crystal X-ray diffraction technique which revealed that the complexes are neutral in charge with distorted octahedral geometry. Further, the stability of the complexes were calculated theoretically and interaction of them with biomolecules resulted in change in binding energies dramatically. Complexes1–3 were evaluated for their interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) using theoretical as well as spectral techniques. In addition, the in vitro cytotoxic potential of the synthesised compounds were investigated against human breast cancer cell models (MCF-7 and MDAMB-453).

Synthesis and characterisation of transition metal complexes of 2-benzoyl pyridine-2,4-dinitrophenyl hydrazone

Derivatization of carbonyl compounds as phenyl hydrazones and 2,4-dinitrophenylhydrazones are of great interest. A new hydrazone ligand was prepared by the condensation of 2-benzoyl pyridine with 2,4-dinitrophenylhydrazine. An interesting series of five new metal complexes of 2-benzoylpyridine-2,4-dinitrophenylhydrazone have been synthesised and physico chemically characterized. The zinc, nickel, copper, cobalt and manganese complexes of the prepared ligand was synthesised and has been characterized by elemental analysis, IR and UV spectroscopy. These complexes have catalytic and analytical applications as well. Sharp band at 1600 cm−1 in the spectrum of the ligand is shifted to lower frequencies in the spectra of the complexes indicate the coordination via azomethine nitrogen. The occurrence of v(N-N) at higher wavenumbers in the spectra of the complexes compared to that of the ligand confirms the coordination of the azomethine nitrogen. Medium bands at 3375 cm−1 for the ligand HL due to v(N–H) vibration and another at 1698 cm−1 due to v(C = O), disappear in the spectra of the complexes providing a strong evidence for the ligand coordination.

Novel NNO pincer type Schiff base ligand and its complexes of Fe(IIl), Co(II) and Ni(II): Synthesis, spectroscopic characterization, DFT, antibacterial and anticorrosion study

A novel NNO pincer type ligand (E)-N'-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide, PPMINH, was synthesized by condensation of 2-benzoyl pyridine and isonicotinylhydrazide. The ligand PPMINH on reaction with metal ions Fe(III), Co(II) and Ni(II) yielded six metal derivatives. Different analysis tools like; Elemental analyses, ESI-MS, FT-IR, molar conductivity, UV-spectra, magnetic susceptibility, NMR and EPR measurement were used. Theoretical FT-IR, 1H NMR and 13C NMR of ligand and complex 6 exhibits quite a good correlation coefficient. EPR spectrum of complex 6 at LNT suggests octahedral geometry around Ni(II). The ligand and complexes were screened for antibacterial activity. DFT has been carried out to optimize the geometry of the ligand and complexes. The properties most relevant to their potential action as corrosion inhibitors has been calculated all parameters of DFT from the inhibitor molecule to the metal atom. The corrosion inhibition effect of compounds on mild steel in an acidic medium was studied for 24, 48, 72 h using weight loss measurement.

Ligand structure-driven self-assembly of Zn(NCS)2 with a carbohydrazone ligand: A possible intermediate towards a [2 × 2] metallic grid

In this work we have synthesized and characterized a new trinuclear heteroleptic discrete zinс(II) complex [Zn3(HL)2(NCS)4], fabricated from a mixture of Zn(NO3)2 and NaNCS with a symmetric and bulky carbohydrazone derived from carbohydrazide and benzoyl pyridine (H2L). The global structure and shape of complex are dictated by two monodeprotonated ligands HL– each coordinating the same Zn(II) ion through one of the pendant arms in an orthogonal fashion, yielding a distorted octahedral N4O2 coordination environment. The second coordination pocket of both ligands each traps Zn(NCS)2 species, yielding an N4O coordination environment. The hexa- and pentacoordinated metals are separated by about 4 Å and positioned almost at a right angle (~87°) addressed by the orientation of organic ligands. The structure of [Zn3(HL)2(NCS)4] is mimicking grid-like structures and can be considered as a possible intermediate towards a [2 × 2] metallic grid. The thiocyanate anions block two of three metal sites that could potentially serve as coordination nodes to fulfil the grid formation. A pair of molecules, arranged about an inversion center, are linked through a pair of (N)C–S···π(Py) noncovalent interactions, which have been rationalized using density functional theory (DFT) calculations, and characterized using the noncovalent interaction plot (NCIplot) index and molecular electrostatic potential (MEP) surface computational tools.

Anticancer potency of copper(II) complexes of thiosemicarbazones

Being a structural and catalytic cofactor in a number of biological pathways, copper accumulates in tumors owing to selective permeability of the cancer cell membranes. Copper(II) ion forms the active centers in a large number of metalloproteins. The coordination of Schiff's base ligands to the metal ion results in the high extent of increase in anticancer activity. The copper(II) complexes can cleave DNA through oxidative and hydrolytic pathways, cell apoptosis via intrinsic reactive oxygen species (ROS) mediated mitochondrial pathway due to excessive production of ROS and hence, are found more active than Ni and Pt complexes. Flexible Cu(I/II) redox behavior helps the copper complexes to form more potent, clinically effective and less toxic copper based antiproliferative drugs of lower IC50 value and higher growth inhibitory activity. Copper(II) complexes of thiosemicarbazones of Isatin, Pyridine, Benzoyl pyridine, Diacetyl/Dimethyl glyoxal, Acetophenone/Acetoacetanalide, Thiazole/Pyrazole, Quinoline, Carboxybenzaldehyde, Cinnamaldehyde/Cuminaldehyde, Citronellal, Chromone, Pyridoxal, 8-Ethyl-2-hydroxytricyclo (7.3.1.02,7) tridecan-13-one, Acyl Diazines, Naphthalene, Proline, 5-Formyluracil, 2-Hydroxy-8-propyltricyclo (7.3.1.02,7) tridecan-13-one, 9-cis-Retinal, Curcumin, Helicin (Salicylaldehyde-β-D-glucoside), Thiophene carboxaldehyde, Salicylaldehyde, Iminodiacetate, and 3-Formyl-4-hydroxy benzenesulfonic acid have been found to exhibit more anticancer activity toward HCT116, MCF7, A549, U937, HeLa, HepG2, SGC-7901, A2780 cell lines than that of their corresponding thiosemicarbazones and standard topoisomerase-II inhibitors.

Synthesis, Structure and Antioxidant Activity of Mixed Ruthenium(III) Benzoyl Pyridine Complex

A new ruthenium arsine complex was prepared by reacting equimolar ratio of [RuBr3(AsPh3)3] and 2-benzoyl pyridine. It was characterized by microanalysis, FT-IR and single crystal X-ray diffraction studies. X-ray diffraction data showed the distorted octahedral geometry of the complex. The pyridine nitrogen and carbonyl oxygen of the ligand coordinated with the metal center. Antioxidant activity of the complex was analyzed using different assays, which manifested significant activity. It has been found that a newly synthesized complex possessed better antioxidant activity than the ligand and precursor complex.

Polynuclear zinc(II) complexes of thiosemicarbazone: Synthesis, X-ray structure and biological evaluation

Two new dimeric Zn(II) ([{ZnL1(DMSO2)}2]·DMSO (1), [{ZnL2Cl}2] (2)) and a novel tetrameric Zn(II) complex ([(Zn2L3)2(μ–OAc)2(μ3–O)2] (3)), where H2L1 = 4–(p–methoxyphenyl) thiosemicarbazone of o–hydroxynapthaldehyde, HL2 = 4–(p–methoxyphenyl)thiosemicarbazone of benzoyl pyridine and H2L3 = 4–(p–chlorophenyl)thiosemicarbazone of o–vanillin are reported. Ligands and their complexes were characterized by spectroscopic and single crystal X–ray diffraction techniques. In addition, the complexes exhibited good binding affinity towards HSA (1012 M−1), which is supported by their ability to quench the tryptophan fluorescence emission spectra of HSA. The complexes were also screened for their DNA binding propensity through UV–vis absorption titration, circular dichroism and fluorescence spectral studies. Results show that they effectively interact with CT–DNA through an intercalative mode of binding, with binding constants ranging from 103 to 104 M−1. Among the three complexes 1 has the highest binding affinity towards CT–DNA. Further, the phosphatase activity was evaluated using bis(2,4–dinitrophenyl)phosphate (BDNPP) as substrate, however, the complexes did not yield any measurable catalytic activity. Nevertheless the complexes showed significant cytotoxic potential against HeLa and HT–29 cancer cell lines that was assessed through MTT assay and DAPI staining. Remarkably, complex 1 showed better activity than cisplatin against HT–29 cell line.

Synthesis, structural characterization, Hirshfeld surface analysis, antimicrobial activity, and DNA cleavage studies of (Z)-4-methyl-N'-(phenyl(pyridin-2-yl)methylene)benzenesulfonohydrazide and its Co(II), Ni(II) and Zn(II) complexes

The NNO tridentate Schiff base ligand of 2-benzoyl pyridine sulfonyl hydrazone (HL) and its transition metal complexes [CoL2] (1), [NiL2] (2) and [ZnL2] (3) have been synthesized and characterized by analytical and spectroscopic studies. The molecular structures of HL and [NiL2] (2) have been investigated by X-ray diffraction and DFT/B3LYP methods. Based on the optimized structures, a single point energy calculation was made for HL and (2) in the different solvent media. The stability of the molecular structures was investigated in different solvent environments by calculating the molecular orbital energies and total energies of the molecular structures. The global reactivity parameters were obtained and the interactions between the molecules with DNA bases such as adenine, cytosine, guanine, and thymine were investigated by using the ECT (electrophilicity-based charge transfer) method and ΔN (charge transfer). Hirshfeld surfaces of HL and (2) complex were investigated and the interaction energies between the molecules participating in C–H⋯O/π interactions in the molecular structures were calculated by using the CE-HF energy model. From elemental analysis data, the metal-ligand ratio of the complexes was found to be 1:2. All compounds were examined for their antimicrobial activity against pathogenic microorganisms by the well-diffusion method. DNA cleavage studies of compounds were screened by the agarose gel electrophoresis method. The results showed that complex (3) showed highly nicking activity, while HL, (1) and (2) complexes didn't show any nicking activity.

Magnetic measurements, Raman and infrared spectra of metal–ligand complex derived from $$\hbox {CoCl}_{2}\cdot \hbox {6H}_{2}\hbox {O}$$ CoCl 2 · 6H 2 O and 2-benzoyl pyridine

Nanocrystalline complex of \(\hbox {CoCl}_{2}\cdot 6\hbox {H}_{2}\hbox {O}{-}2\)-benzoyl pyridine is prepared by chemical route. Each component of the desired complex is identified by analysing the X-ray diffractograms. Energy-dispersive X-ray analysis (EDX) data confirmed the presence of the desired elements of the sample. Theoretical optimized structure of the complex was derived using ab initio density functional level of theory (DFT) method of calculation. The average nanocrystallite size estimated from the XRD data is \(\sim \)43 nm. Static magnetic property of the complex is studied in the temperature range from 300 K down to 14 K. The estimated magnetic moment of the complex is high when compared to that of the free ion magnetic moment of \(\hbox {Co}^{2+}\) and this is attributed to the less effect of the crystal field acting on the ion in the organic complex due to which orbital moments are not fully quenched. The magnetic property of the complex is also remarkably enhanced compared to that of the diamagnetic 2-benzoyl pyridine which may be suitable for applications in devices. FTIR and Raman spectra of the ligand, 2-benzoyl pyridine and the synthesized complex are recorded at room temperature, which not only confirm the presence of each phase in the complex, but some interesting results are also extracted from the analyses of different Raman active modes of the complex.

Identification of the Substitutes on α‐(N)‐Heterocyclic Thiosemicarbazones that Interact with Human Topoisomerase‐II‐α with Nuclear Magnetic Resonance

Topoisomerase IIα (TopoIIα) is an essential enzyme for cell proliferation. Cancer cells are rapidly dividing cells. Thus, TopoIIα is a primary target for many anticancer drugs. Thiosemicarbazones (TSCs) have been known to possess anticancer activity by inhibiting topoisomerase‐II. Recent studies of our lab found the structure‐activity relationship of TSCs and their inhibition on TopoIIα. Our results suggest that the metal ion of TSC metal complexes and the terminal nitrogen side chain play important roles in increasing TopoIIα‐mediated cleavage complexes. The direct interaction between TSCs and TopoIIα remains unknown. It is hypothesized by our lab that the metal ions and the terminal nitrogen side chains interact with TopoIIα directly. This hypothesis is being tested by studying the interaction of 2‐acetylthiazole (ATZ) TSC, 2‐acetyl‐4‐methylthiazole (AMT) TSC, and benzoylpyridine (BZP) TSC metal complexes with TopoIIα by saturation transfer difference nuclear magnetic resonance (STD‐NMR) and diffusion ordered spectroscopy nuclear magnetic resonance (DOSY‐NMR). Recent STD‐NMR experiments suggest that the aliphatic region of 2‐acetylthiazole (ATZ) TSC and benzoylpyridine (BZP) TSC interact with TopoIIα.Support or Funding InformationThis research is supported by the Faculty Research Grant (XJ) and the NSF MRI project (1531870).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Cu(ii) metal-organic framework with significant H2 and CO2 storage capacity and heterogeneous catalysis for the aerobic oxidative amination of C(sp3)-H bonds and Biginelli reactions.

A Cu(ii) metal-organic framework, {[Cu2(L)(H2O)2]·(5DMF)(4H2O)}n (1), has been synthesized using an angular tetracarboxylic acid ligand (H4L) incorporating both trifluoromethyl (-CF3) and amine (-NH2) groups. Notably, the framework possesses high water and thermal stability. At atmospheric pressure, the activated framework 1' exhibits substantially high amounts of CO2 (35.5 and 20.8 wt% at 273 and 298 K respectively) and H2 (1.72 wt% at 77 K) adsorption. Also, 1' exhibits excellent catalytic activity for the condensation-cyclization reaction between 2-benzoyl pyridine and different benzylamines via oxidative amination of the C(sp3)-H bond to form 1,3-diarylated imidazo[1,5-a]pyridines under mild aerobic conditions. In addition to this, 1' shows excellent heterogeneous catalytic activity in Biginelli reactions. The solid catalyst could be recycled several times without significant loss in the catalytic activities.

Synthesis, characterization and molecular modeling of some transition metal complexes of Schiff base derived from 5-aminouracil and 2-benzoyl pyridine

Multidentate Schiff base (H2L) ligand results from condensation of 5-aminouracil and 2-benzoyl pyridine and its metal chloride (Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Fe(III), Cr(III), Ru(III), Zr(IV) and Hf(IV)) complexes were prepared. The structural features of the ligand and its metal complexes were confirmed by elemental analyses, spectroscopic methods (IR, UV–Vis, 1H NMR, mass), magnetic moment measurements and thermal studies. The data refer to the ligand coordinates with metal ions in a neutral form and shows different modes of chelation toward the metal atom. All complexes have octahedral skeleton structure, tetrahedrally Mn(II), Ni(II), trigonalbipyramidal Co(II) and square planner Pd(II). Thermal decomposition of complexes as well as the interaction of different types of solvent of crystallization are assigned by thermogravimetric analysis. Molecular modeling of prepared complexes were investigated to study the expected anticancer activities of the prepared complexes. All metal complexes have no interaction except the complexes of Pd(II), Fe(III) and Mn(II).

Syntheses, single crystal structures, DFT and antioxidant superoxide dismutase studies of some new mono-/binuclear copper(II) complexes

A series of mono- and binuclear copper(II) complexes have been synthesized using HL1 and other mono- and bidentate ligands (L2) [HL1=N′-[(E)-phenyl(pyridin-2-yl)methylidene]thiophene-2-carbohydrazide, L2=2-benzoyl pyridine (BP), neocuprin, imidazole (ImH) and pyrazine] by a one pot synthesis. These complexes were characterized by routine physico-chemical techniques. The single crystal X-ray structures of 1, 2, 3 and 5 were determined. X-ray single crystal analyses reveal that complex 1 is six coordinated while complex 2 is a penta coordinated complex. Complex 3 is pseudo binuclear while 4 and 5 are binuclear complexes. Intermolecular π…π stacking interactions could be detected in the solid medium and classical H-bonding interactions lead to infinite 1D chains and to an infinite 2D network in 2. Variable temperature magnetic susceptibility data display antiferromagnetic couplings in 3–5. The X-band epr spectra for polycrystalline samples of 3–5 exhibit copper(II) hyperfine structure as well as zero-field splitting which are appropriate for the triplet state of such a dimer. Epr data also indicate antiferromagnetic behavior for binuclear complexes 3–5. Binuclear complexes were also studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The conproportion constant (Kcon) of complexes 3–5 have been evaluated and discussed. Modeling by DFT and TD-DFT is done to elucidate the nature and location of the excited state in superoxide dismutase (SOD) mimics. In addition, antioxidant SOD activity showed that HL1 and its copper(II) complexes possess significant scavenging effect against O2− free radicals.

Synthesis, structural investigation, DNA and protein binding study of some 3d-metal complexes with N′-(phenyl-pyridin-2-yl-methylene)-thiophene-2-carboxylic acid hydrazide

The ligand, N′-(phenyl-pyridin-2-yl-methylene)-thiophene-2-carboxylic acid hydrazide (Hpmtc) derived from thiophene-2-carboxylic acid hydrazide and 2-benzoyl pyridine, and its metal complexes with Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized. These compounds are characterized by elemental analyses, magnetic susceptibility measurements, IR, NMR and UV–Vis spectral studies. The molecular structures of Hpmtc and its Co(II) (1), Ni(II) (2), Cu(II) (3) and Zn(II) (4) complexes are finally determined by X-ray crystallography. Various spectral and single-crystal X-ray diffraction studies suggest that Hpmtc coordinates with metal ions as a monobasic tridentate ligand forming mononuclear distorted octahedral complexes of the type [M(pmtc)2]. The molecular structures of the complexes are stabilized by CH⋯N, CH⋯O intermolecular H-bonding, and CH⋯π and π⋯π interactions. The DNA binding experiment of the complexes 1, 3 and 4 by UV–Vis absorption, and EB-DNA displacement by fluorescence spectroscopy, reveal an intercalative mode of binding between CT-DNA (calf-thymus DNA) and the metal complexes. These complexes exhibit a moderate ability to cleave pBR322 plasmid DNA. A comparative bovine serum albumin (BSA) protein binding activity of the complexes 1, 3 and 4 has also been determined by UV–Vis absorption and fluorescence spectroscopy. The DNA binding and protein binding studies suggest that the complex 3 exhibits more effective binding activity (Kb=5.54×105 and Kq=1.26×106M−1, respectively) than complexes 1 and 4. However, the complex 1 shows better hydrolytic DNA cleavage activity compared to 3 and 4 complexes.

An investigation on new ruthenium(ii) hydrazone complexes as anticancer agents and their interaction with biomolecules

A new set of ruthenium(II) hydrazone complexes [Ru(H)(CO)(PPh3)2(L)] (1) and [RuCl2(DMSO)2(HL)] (2), with triphenyl phosphine or DMSO as co-ligands was synthesized by reacting benzoyl pyridine furoic acid hydrazone (HL) with [Ru(H)(Cl)(CO)(PPh3)3] and [RuCl2(DMSO)4]. The single crystal X-ray data of complexes 1 and 2 revealed an octahedral geometry around the ruthenium ion in which the hydrazone is coordinated through ON and NN atoms in complexes 1 and 2 respectively. The interaction of the compounds with calf thymus DNA (CT-DNA) has been estimated by absorption and emission titration methods which indicated that the ligand and the complexes interacted with CT-DNA through intercalation. In addition, the DNA cleavage ability of these newly synthesized ruthenium complexes assessed by an agarose gel electrophoresis method demonstrated that complex 2 has a higher DNA cleavage activity than that of complex 1. The binding properties of the free ligand and its complexes with bovine serum albumin (BSA) protein have been investigated using UV-visible, fluorescence and synchronous fluorescence spectroscopic methods which indicated the stronger binding nature of the ruthenium complexes to BSA than the free hydrazone ligand. Furthermore, the cytotoxicity of the compounds examined in vitro on a human cervical cancer cell line (HeLa) and a normal mouse embryonic fibroblasts cell line (NIH 3T3) revealed that complex 2 exhibited a superior cytotoxicity than complex 1 to the cancer cells but was less toxic to the normal mouse embryonic fibroblasts under identical conditions.

Synthesis, characterization, DNA interaction, thermal and in vitro biological activity investigation of some Ni(II)-Isatin bishydrazone complexes

Complexes of the type [Ni (L) (H2O)] Cl2.nH2O, where L = [(pyridine-2-carboxaldhyde)-3-isatin]-bishydrazone (cpish), [(2-acetyl pyridine)-3-isatin]-bishydrazone (apish) and [(2-benzoyl pyridine)-3-isatin]-bishydrazone (bpish) have been synthesized and characterized on the bases of elemental analysis, molar conductance, IR, NMR, electronic spectra and thermal analysis (TGA and DTA). Moreover, the stoichiometry and the formation constants of these complexes have been determined spectrophotometrically. Kinetics and thermodynamic parameters of the thermal decomposition have been computed from the thermal data using Coats and Redfern method, which confirm first-order kinetics. The bioefficacy of the ligands and their complexes have been examined for their in vitro antibacterial and antifungal activity against many types of bacteria and anti fungal cultures, which are common contaminants of the environment in Egypt, and the results indicate that the ligands and their metal complexes possess notable antimicrobial activity. Investigation of their interaction with CT-DNA under physiological conditions, using spectroscopic (UV–visible) and hydrodynamic techniques (viscosity measurements). Binding constant "K b" obtained from spectroscopic methods revealed significant binding of compounds with DNA via intercalation, Furthermore, free energies of compounds–DNA interactions indicated spontaneity of their binding.

Synthesis, characterization, anti-fungi and anti-bacterial activity of new [(2-pyridyl)-3-isatin]-bishydrazone

New [(pyridine-2-carboxaldhyde)-3-isatin]-bishydrazone (cpish), [(2-acetylpyridine)-3-isatin]-bishydrazone (apish), and [(2-benzoyl pyridine)-3-isatin]-bishydrazone (bpish) have been synthesized and characterized by the elemental analysis, IR, NMR and electronic spectra. The bioefficiency of the [(2-pyridyl)-3-isatin]-bishydrazones have been examined for their in-vitro antibacterial and antifungal activity against many types of bacteria and fungal cultures which are common contaminants of the environment in Egypt and some of which are involved in human and animal diseases or in plant diseases or frequently reported from contaminated soil, water, and food substances. The results of these studies indicate that the [(2-pyridyl)-3-isatin]-bishydrazones possess notable antimicrobial properties.

Five new pseudohalide bridged Mn(II) complexes of pyrimidine derived Schiff base ligands: Synthesis, crystal structures and magnetic properties

Four new azide bridged dinuclear Mn(II) complexes [Mn(L1)(μ1,1-N3)(N3)]2 (1), [Mn(L2)(μ1,1-N3)(N3)]2 (3), [Mn(L3)(μ1,1-N3)(N3)]2[(N3)Mn(L3)(μ1,1-N3)(N3)]2 (4) and [Mn(L4)(μ1,1-N3)(N3)]2[Mn(L4)(μ1,1-N3)(N3)]2 (5) and one new dicynamide bridged binuclear Mn(II) complex {[Mn2(L1)2(dca)2(H2O)2(μ1,5-dca)](ClO4)} (2) have been synthesized using the pyrimidine derived primary Schiff base ligands Ln (n=1–4), with azide and dicynamide as bridging ligands. All the five complexes were characterized by elemental analyses, IR spectroscopy and single crystal X-ray crystallography, together with magnetic measurements of 1–4. The tridentate Schiff base ligands are the [1+1] condensation products of 2-hydrazino-4,6-dimethyl pyrimidine with 2-acetyl pyridine, pyridine-2-carbaldehyde, 2-benzoyl pyridine and di(2-pyridyl) ketone for Ln (n=1–4), respectively. All the complexes except 2 contain Mn(II)-azido links in which the Mn(II) centres are bridged by a di-μ1,1-azido (double EO) group. The double EO bridging fragments in the complexes are similar with bridging angles (Mn–N–Mn) ranging from 102.59° to 104.81°. Magnetic property studies reveal that in 1, 3 and 4 intramolecular ferromagnetic interactions are mediated through the EO azido bridges with J parameters in the range 4.3–5.12cm−1, while a weak antiferromagnetic interaction prevails in 2 (J=−0.12cm−1) via μ1,5-dicynamide bridges. In addition, complexes 1, 3 and 4 show weak intermolecular antiferromagnetic interactions (J=−0.025 to −0.027cm−1).

Efficient synthesis and development of novel hydrazones with potent diverse activities

A series of hydrazones and Schiff bases have been prepared by an efficient route from reaction between hydrazine derivatives and carbonyl compounds such as di- (2-pyridyl) ketone, 2-benzoyl pyridine, and 2-thiophencarbaldehyde in the presence of sodium acetate.

Zinc(ii), iron(ii/iii) and ruthenium(ii) complexes of o-phenylenediamine derivatives: oxidative dehydrogenation and photoluminescence

Reactions of benzoyl pyridine, o-phenylenediamine and anhydrous ZnX2 in methanol afford imine complexes [Zn(L1)X2] (X = Cl, 1; X = Br, 2) in good yields (L1 = (E)-N(1)-(phenyl(pyridin-2-yl)methylene)benzene-1,2-diamine). The reduction of 1 with NaBH4 affords (E)-N(1)-(phenyl(pyridine-2-yl)methylene)benzene-1,2-diamine (L2H). The reaction of L2H with [Ru(II)(PPh3)3Cl2] results in the oxidative dehydrogenation to L1 generating cis-[Ru(II)(L1)(PPh3)Cl2] (3). The reaction of L2H with salicylaldehyde affords (E)-2-(((2-((phenyl(pyridin-2-yl)methyl)amino)phenyl)imino)methyl)phenol (L3H2). The reaction of L3H2 with anhydrous FeCl3 in CH3OH affords cis-[Fe(III)(L3H(-))Cl2] (4). Reaction of L3H2 with [Ru(II)(PPh3)3Cl2] results in the oxidative dehydrogenation to diimine, L4H, affording trans-[Ru(II)(L4(-))(PPh3)2](+), which is isolated as trans-[Ru(II)(L4(-))(PPh3)2]PF6 (5(+)PF6(-)) (L4H = 2-((E)-(2-((E)-phenyl(pyridin-2-yl)methyleneamino)phenylimino)methyl)phenol). The reduction of L3H2 with NaBH4 produces 2-(((2-((phenyl(pyridin-2-yl)methyl)amino)phenyl)amino)methyl)phenol (L5H3). With iron(III) L5H3 undergoes oxidative dehydrogenation to L3H2 affording 4, while with [Ru(II)(PPh3)3Cl2], L5H3 undergoes 4e + 4H(+) transfer giving 5(+). A fluid solution of L3H2 at 298 K exhibits an emission band at 470 nm (λ(ex) = 330 nm, τ1 = 3.70 ns) and a weaker band at 525 nm (λ(ex) = 330, 390 nm, τ1 = 1.1 ns) at higher concentrations due to molecular aggregation, which are temperature dependent. 4 is brightly emissive (λ(ex) = 330 nm, λ(em) = 450 nm, Φ = 0.586, τ1 = 3.70 ns). Time resolved emission spectra (TRES) and lifetime measurements confirm that the lower energy absorption band of L3H2 at 390 nm, which is absent in complex 4, has a larger non-radiative rate constant (k(nr)). The redox innocent Al(III) adduct of L3H2 is fluorescent (λ(ex) = 330 nm, λ(em) = 450 nm, τ1 = 3.70 ns). On the contrary, the cis-[Fe(II)(L3H(-))Cl2](-) and cis-[Co(L3H(-))Cl2](-) analogues are non emissive. Density function theory (DFT) calculations, redox potentials and the near infra-red (NIR) absorption data prove that 4 is emissive due to the stable [Fe(III)(L3H(-)*)] state, while 3, 5(+), cis-[Fe(II)(L3H(-))Cl2](-) and cis-[Co(L3H(-))Cl2](-) are non-emissive due to transformations of the [M(II)(L*)] to [M(III)(L˙(-)*)] states.