A convenient synthesis of a library of tetrazoles through a novel and operationally simple protocol effecting the direct conversion of arylboronic acids catalyzed by a new ONO pincer-type Pd(II) complex under mild reaction conditions using the readily available reagents is reported. The palladium complex was reused up to four cycles in an open-flask condition.

Two new stable ruthenium complexes, [RuIII(HL)Cl2(PPh3)2] (1) and [RuII(L)(CO)(PPh3)2] (2), were synthesized from the reaction of [RuIIICl3(PPh3)3] with thiophene-2-carboxylic acid (2-hydroxyl-benzylidene)-hydrazide (H2L) in chloroform–methanol. Surprisingly, the same reaction performed by adding KOH to the reaction medium resulted in the exclusive formation of the bivalent ruthenium carbonyl complex 2. Both complexes 1 and 2 were characterized by elemental analysis, EPR/NMR and single crystal X-ray diffraction study. From the DNA binding and quenching experiments, an intercalative mode of binding with DNA was identified. The DNA cleavage activity of the complexes, monitored using gel electrophoresis, showed significant damage of the plasmid DNA. Bovine serum albumin (BSA) binding capabilities analysed using absorption and emission spectroscopic methods showed a strong binding interaction of complexes 1 and 2 with BSA. The in vitro cytotoxicity studied against human breast cancer cell models (MCF-7 and MDAMB-453) showed that complex 1 possessed activity comparable to that of the standard positive reference cisplatin. The IC50 concentration of complexes treated with cancer cell models exhibited a significant increase in lactate dehydrogenase release and nitrite content in the culture medium. Overall, the trivalent ruthenium hydrazone complex 1 exhibited better activity towards biomolecules and cancer cells than complex 2.A new set of ruthenium(III) hydrazone complexes have been reported with their crystal structures. Their biomolecular interaction studies with DNA/BSA indicated a strong interaction. In vitro cytotoxicity analyses done with human breast cancer cell models (MCF-7 and MDAMB-453) established the anticancer potential of these complexes.Download high-res image (98KB)Download full-size image

One-pot, tandem C–H and N–H activation of acetanilides with aryl boronic acids to realize functionalized carbazoles was conveniently performed under aerobic conditions using a novel NNO pincer type Pd(II) complex [Pd(L)Cl] (where L = nicotinic acid (phenyl-pyridin-2-yl-methylene)-hydrazide or furan-2-carboxylic acid (phenyl-pyridin-2-yl-methylene)-hydrazide) as a catalyst in neat water and a very low (0.01 mol%) amount of catalyst. It is worth noting that recyclability up to six consecutive runs and column chromatography free isolation of the title heterocycles in an excellent yield are achieved.

A set each of new bivalent and trivalent ruthenium complexes, [RuIII(HL)Cl2(EPh3)2] and [RuII(L)(CO)(EPh3)2] (E = P (complexes 1 and 2) or As (complexes 3 and 4)) were synthesised from the reactions of [RuIIICl3(EPh3)3] with 2-hydroxynaphthaldehyde benzoic acid hydrazone (H2L) in methanol–chloroform and characterized by elemental analysis, spectral data and XRD study. A suitable mechanism to account for the formation of bivalent ruthenium carbonyl complexes from the corresponding trivalent precursors is provided by considering the role of added base in the reaction. Interaction of complexes 1–4 with CT-DNA/bovine serum albumin was analysed with absorption and emission spectral titration studies. In vitro cytotoxic potential of the above ruthenium hydrazone complexes 1–4 assayed against the A549 cell line revealed a significant growth inhibition. The test complexes 1–4 added in IC50 concentration into the cell culture medium enhanced the release of lactate dehydrogenase, NO and reactive oxygen species in comparison with the control. Cell death induced by the complexes was studied using a propidium iodide staining assay and showed noticeable changes in the cell morphology which resembled apoptosis.

•First report on the Pd(II) pincer type complex catalyzed C-2 arylation of 2-oxinolde.•Low catalyst loading (0.01 mol%) with higher yield.•Practical advantages such as scalability and reusability are significant.•Convenient methodology to obtain biologically significant heterocycles.Pd(II) complexes appended with ONO pincer type ligand were synthesized, structurally characterized and successfully applied as catalysts for regieoselective C−2 arylation of 2-oxindole via in situ C (sp2)−OH activation in aqueous-organic media under an open atmosphere at room-temperature. This catalyst was reused up to four cycles. Favourably, the present protocol doesn't require the addition of any external oxidant, additives or phase transfer agents.

Gas sensors were fabricated using nanostructured indium oxide (In2O3) and platinum doped indium oxide (Pt-In2O3) prepared by surfactant assisted hydrothermal method. The optimum working temperature of the sensors was around 165 °C, which is lower than the literature reports. The sensor fabricated using Pt-In2O3 exhibited higher response as compared to undopedIn2O3.Their gas sensing properties investigated with NO2 gaswith2.5 and 5 ppmrevealed that the sensors showed a concentration dependent electrical resistance.

Facile synthesis of three new palladium(II) complexes bearing heterocyclic hydrazone ligands are presented along with their structural characterization using IR, 1H and 13C NMR spectra. Molecular structures of the complexes determined by single-crystal XRD revealed a distorted square-planar geometry around the metal ion to which the hydrazone was attached in a tridentate fashion. Catalytic activity of these complexes tested towards the Suzuki–Miyaura cross coupling reaction of substituted aryl boronic acids with aryl chlorides in a water–toluene system (90:10%) without using any promoting additives or phase transfer agents, proved that they are highly active with 0.01 mol% loading under optimized conditions to afford 99% yield of the coupled product. Effects of temperature, solvent and base on the cross-coupling reaction were carried out as well. These complexes showed significant catalytic activity up to five cycles.

Four new palladium(II) complexes featuring ONO pincer type hydrazone ligands were synthesized and characterized by spectroscopic and single-crystal XRD analysis. These complexes showed excellent catalytic activity towards the Suzuki–Miyaura cross coupling reaction of 2-chloroquinoline derivatives with various aryl boronic acids. The main advantages over previous methodologies include low catalyst loading, less problematic reaction media (H2O–DMF (80:20%)) and a lower reaction temperature of 60 °C for optimal performance.

•Two new ruthenium(III) complexes containing hydrazones were prepared.•Single crystal XRD confirmed an octahedral geometry around the metal ion in these complexes.•DNA interaction studies showed intercalative mode of binding.•Cytotoxicity studies on A549 cell lines showed significant activity.•An increase in the LDH, NO and ROS generation in A549 cells was observed.A new set of ruthenium(III) aroylhydrazone complexes [RuCl2(PPh3)2(HL1)] (1) and [RuCl(PPh3)2(L2)] (2) were synthesized by reacting salicylaldehyde p-toluic acid hydrazone (H2L1) or 2-hydroxy-acetophenone p-toluic acid hydrazone (H2L2) and [RuCl3(PPh3)3] precursor complex and characterized. Single crystal X-ray diffraction data of these complexes revealed a distorted octahedral geometry around ruthenium ions fulfilled by NOP2Cl2 atoms and NO2P2Cl atoms, respectively. Though the ligands look similar in respect of structure and donor sites, the existence of H-bonding between the phenolic –OH and N2 nitrogen of the coordinated ligand H2L1 as revealed by the single crystal data of complex 1 is attributed to the non-involvement of the hydroxyl group in coordination to the ruthenium ion which is in sharp contrast to the behaviour exhibited by the ligand H2L2 in complex 2. As a result, the ligand H2L1 acted as a monobasic bidentate against the dibasic tridentate behaviour of the ligand H2L2. Binding interactions of these complexes with calf thymus-DNA (CT-DNA) estimated by absorption and emission spectroscopy did demonstrate the intercalative mode of binding. The capability of complexes 1 and 2 to bind with bovine serum albumin (BSA) protein was monitored by quenching of tryptophan and tyrosine residues using UV–Vis, fluorescence and synchronous fluorescence methods. Further, in vitro cytotoxicity of the complexes was carried out using MTT, lactate dehydrogenase (LDH), Nitric oxide (NO), reactive oxygen species (ROS) and propidium iodide (PI) staining assays against non-small cell lung cancer cell line (A549).A new set of ruthenium(III) aroylhydrazone complexes have been reported with their crystal structure. Their DNA/protein binding studies indicated a strong interaction with the biomolecules. In vitro cytotoxicity analyses done with A549 cell lines established the anticancer potential of the complexes 1 and 2.

•Two new, chloro-bridged binuclear copper-hydrazone complexes were synthesized.•The complexes exhibited intercalative mode of interaction with DNA.•Both the binuclear complexes bind with BSA via static interaction.•One of the complexes showed more toxicity to HeLa cell lines (IC50 = 0.7 μM).Two new, binuclear copper(II) hydrazone complexes have been synthesized and characterized by various physico-chemical techniques including single crystal X-ray diffraction. Interaction of these complexes with nucleotide and protein were analyzed by in vitro biochemical and electrochemical analysis. Both the complexes exhibited intercalative mode of binding with DNA. Further, gel electrophoresis assay demonstrated the ability of the complexes to cleave the supercoiled pBR322 plasmid DNA to nicked circular DNA form. Cytotoxicity of the complexes performed against a panel of cancer cell lines and a normal cell line proved that these complexes are potentially cytotoxic against the cancerous cell lines, particularly with IC50 as low as 0.7 μM against HeLa cell line.Two new binuclear copper(II) complexes possessing square-pyramidal geometry were synthesized and the complex 1 exhibited very high cytotoxicity (IC50 = 0.7 μm) to arrest the growth of cancer cells.

Synthesis, spectral, electrochemical and single crystal X-ray diffraction data of a new series of DMSO containing bivalent ruthenium hydrazone complexes are presented. XRD data of two of the new complexes revealed an octahedral coordination around the ruthenium ion satisfied by NOS2Cl2 atoms. Electrochemical studies showed the metal centred, quasi-reversible, one-electron redox behaviour of the new complexes. The binding of these complexes with biomolecules such as calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) protein investigated by different spectrophotometric methods revealed an intercalative mode of interaction. The in vitro cytotoxicity of these complexes evaluated by the MTT assay on a panel of cancer and normal cell lines indicated that the above complexes are more toxic to cancer cells with a few micromolar concentrations as the IC50 value, but are significantly less toxic to normal cell lines. The observed variations in the binding interactions and cytotoxicity of the complexes were attributed to the nature of the hydrazide moiety of the hydrazones that influences their biological activities.

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 of new copper(II) pincer type hydrazide complexes.•Binding interaction with both DNA and protein was estimated.•In vitro free radical scavenging and cytotoxicity studies were also performed.Four new, pincer type copper complexes 5–8 were synthesised from the reactions of CuCl2·2H2O with respective hydrazide ligands 1–4 (HL1–HL4) and characterized by various physicochemical techniques. The single crystal XRD and spectral data revealed that all the ligands are monoanionic, tridentate pincer analogues chelating agent, which coordinate via ONN donor atoms to the copper ion. The effect of electronegativity and ring size of heterocyclic hydrazide moiety of ONN pincer type copper(II) chelates on nucleic acid interaction and protein binding was investigated by in vitro experiments. In addition, scavenging activity and cytotoxicity of the newly synthesized complexes of the composition [Cu(L1–4)Cl] were also evaluated.The synthesis and characterisation of pincer type bivalent copper hydrazide complexes of the composition [Cu(L1–4)Cl] have been presented.In vitro biological evaluations such as DNA/protein binding, radical scavenging and cytotoxicity were carried out.

•Hydrothermally prepared In(OH)3 was sintered at 400, 500 and 600 °C.•Conversion of In(OH)3 to In2O3 was ascertained by TGA and FT-IR spectroscopy.•Crystallite size and percentage crystallinity were derived from powder XRD analysis.•SEM, TEM and EDX revealed the morphology and elemental composition.•Band gap and PL emission were evaluated from UV–Vis and PL spectroscopy.Indium(III) hydroxide (In(OH)3) powders prepared via Triton X-100 mediated hydrothermal method was sintered at different temperatures (400, 500 and 600 °C) to yield indium(III) oxide nanoparticles (In2O3 NPs). Thermal studies of In(OH)3 confirmed complete conversion to In2O3 around 400 °C. Powder X-ray diffraction (XRD) pattern of sintered In2O3 nanoparticles revealed the formation of phase pure cubic In2O3. The crystallite size of In2O3 NPs was increased from 12 to 26 nm upon increasing the sintering temperature from 400 °C to 600 °C, while the percentage crystallinity was increased up to 90% after sintering at 600 °C. A red shift in the band gap energy was observed with increasing sintering temperature due to the larger size of sintered In2O3 NPs. Room temperature photoluminescence spectra of the indium oxide nanoparticles showed both near band and excitonic emission of In2O3 due to oxygen vacancies.Graphical abstract

A new set of penta-coordinated copper(II) hydrazone complexes containing solvated methanol were synthesized by reacting the hydrazone ligands, 2-acetylpyridine benzoyl hydrazone (HL1) and 2-acetylpyridine thiophene-2-carboxylic acid hydrazone (HL2), with [CuCl2(DMSO)2] and characterized by different spectral methods. Single crystal X-ray diffraction studies of the complexes revealed that both of them, [CuCl(L1)(MeOH)] (1) and [CuCl(L2)(MeOH)] (2), have square pyramidal geometry around the cupric ion, in which the hydrazone is coordinated through NNO atoms along with a molecule of methanol in the apical position. Interaction of the ligands HL1 and HL2 along with the corresponding copper complexes 1 and 2 with calf thymus DNA (CT-DNA) has been estimated by absorption and emission titration methods which revealed that the compounds interacted with CT-DNA through intercalation. Binding of the compounds, i.e., free ligands and complexes (1) and (2) with bovine serum albumin (BSA) protein investigated using UV-visible, fluorescence and synchronous fluorescence spectroscopic methods indicated that there occurred strong binding of copper complexes to BSA over the ligands. Further, the cytotoxicity of the compounds examined in vitro on a panel of cancerous cell lines such as a human cervical cancer cell line (HeLa), a pancreatic cancer cell line (PANC-1), an Ehrlich ascites cancer cell line (EAC) and Dalton's lymphoma ascitic cancer cells (DLA) and a normal mouse embryonic fibroblasts cell line (NIH3) demonstrated that the complexes 1 and 2 possessed superior cytotoxicity than that of well-known commercial anticancer drug cisplatin to the tumor cells but are less toxic to the normal cell line and have emerged as potential candidates for further studies.

Two new copper(I) hydrazone complexes have been synthesised from bivalent copper precursor [CuCl2(PPh3)2] and ferrocene containing bidentate hydrazone ligands HL1 (1) or HL2 (2). Based on the elemental analyses and spectroscopic data, the complexes are best formulated as [CuL1(PPh3)2] (3) and [CuL2(PPh3)2] (4) of the monovalent copper ion. Solid state structures of ligand 2 and its corresponding complex 4 were also determined. The DNA/albumin interactions of all the synthesised compounds were investigated using absorption, emission and synchronous fluorescence studies. Further, antioxidant properties of all the compounds have also been checked against ABTS, O2− and OH radicals. Additionally, the in vitro cytotoxic activity of compounds 1–4 was assessed using tumour (HeLa, A431) and non-tumour (NIH 3T3) cell lines.

Bivalent, ruthenium organometallics containing hydrazone ligands with the composition [RuH(CO)(PPh3)2(L1−3)] (4–6) have been synthesised from the reactions of [RuH2(CO)(PPh3)3] and benzoic acid pyridine-2-ylmethylene-hydrazide (HL1) (1) /benzoic acid (1-pyridin-2-yl-ethylidene)-hydrazide (HL2) (2)/benzoic acid (phenyl-pyridin-2-yl-methylene)-hydrazide (HL3) (3) and characterised by various physico–chemical techniques. The X-ray crystal structure of one of the above complexes, [RuH(CO)(PPh3)2(L3)] (6) demonstrated a distorted octahedral coordination geometry around the metal centre. Results of our investigation on the effect of substitution (H or CH3 or C6H5) at the azomethine carbon of coordinated hydrazone in these ruthenium chelates on the potential binding with DNA/BSA, free radical scavenging and cytotoxicity is presented.Graphical abstractRuthenium(II) organometallic hydrazone complexes were synthesised, characterised and biological evaluations were carried out.Highlights► Synthesis of new ruthenium carbonyl hydrazone complexes with octahedral geometry. ► All the new complexes showed significant interaction with both DNA and protein. ► Free radical scavenging and cytotoxicity results proved their efficacy.

Three new bivalent nickel hydrazone complexes have been synthesised from the reactions of [NiCl2(PPh3)2] with H2L {L = dianion of the hydrazones derived from the condensation of o-hydroxynaphthaldehyde with furoic acid hydrazide (H2L1) (1)/thiophene-2-acid hydrazide (H2L2) (2)/isonicotinic acid hydrazide (H2L3) (3)} and formulated as [Ni(L1)(PPh3)] (4), [Ni(L2)(PPh3)] (5) and [Ni(L3)(PPh3)] (6). Structural characterization of these compounds 4–6 were accomplished by using various physico-chemical techniques. Single crystal X-ray diffraction data of complexes 4 and 5 proved their distorted square planar geometry. In order to ascertain the potential of the above synthesised compounds towards biomolecular interactions, additional experiments involving interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) were carried out. All the ligands and corresponding nickel(II) chelates have been screened for their scavenging effect towards O2−, OH and NO radicals. The efficiency of complexes 4–6 to arrest the growth of HeLa, HepG-2 and A431 tumour cell lines has been studied along with the cell viability test against the non-cancerous NIH 3T3 cells under in vitro conditions.

Reactions of tridentate chelating hydrazone Schiff bases benzoic acid (2-hydroxyl-benzylidene)-hydrazide (H2L) (1) obtained from salicylaldehyde and benzhydrazide with [NiCl2(PPh3)2] and [CoCl2(PPh3)2] afforded respective metal hydrazone complexes of the composition [Ni(L)(PPh3)] (2) and [Co1(L)2]2[Co2(H2O)4(OPPh3)2] (3). The molecular structure of both complexes 2 and 3 determined by single crystal X-ray diffraction revealed that complex 2 is neutral in charge with distorted square planar geometry. However, complex 3 was found to have distorted octahedral geometry. All of the synthesised compounds 1–3 were studied by interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA). In addition in vitro free radical scavenging and cytotoxic potential of all the synthesised compounds were also investigated.

Three new transition metal complexes of the type ML2 (where M = Ni(II), Co(II) or Cu(II); HL = N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide]) have been prepared by treating [NiCl2(PPh3)2], [CoCl2(PPh3)2] or [CuCl2(PPh3)2] with N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide derived from furoic acid hydrazide and 2-benzoyl pyridine wherein the hydrazone ligand (L) coordinated to the respective metal ions in 1:2 stoichiometry to mononuclear octahedral complex. The crystal structure of the complexes [NiL2] (1), [CoL2] (2) and [CuL2] (3) solved using single crystals revealed a distorted octahedral geometry around the metal ion involving the coordination of an azomethine nitrogen, a pyridine nitrogen and an enolic oxygen derived from deprotonation of the ligand. From the bioinorganic application point of view, a detailed work on the binding of the complexes 1, 2 and 3 with CT DNA as well as BSA was undertaken along with DNA cleavage. In vitro assay on the antioxidant activity of the above complexes and hydrazone ligand revealed that they possess significant antioxidant activity. However, among the newly synthesized hydrazone complexes, complex 3 having coordinated Cu2+ ion in its molecular structure exhibited superior activity in all the biological studies in comparison with the other two complexes possessing nickel and cobalt ions with same ligand (L).Graphical abstractTransition metal hydrazone complexes were synthesized, characterized and biological evaluations were carried out.Highlights► Synthesis of N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide ligand. ► Synthesis of Ni(II), Co(II) and Cu(II) hydrazone complexes. ► Structural characterization involving single crystal XRD. ► DNA/protein interactions and antioxidant studies were carried out.

Bivalent transition metal hydrazone complexes of the composition [Ni(L1)2] (1), [Co(L1)2] (2), [Ni(L2)2] (3) and [Co(L2)2] (4) have been synthesised from the reactions of [MCl2(PPh3)2] (where M = Ni or Co) with hydrazones derived from 2-acetyl pyridine and carboxylic acid hydrazides of benzhydrazide (HL1) or thiophene-2-carboxylic acid hydrazide (HL2), respectively. Structure of the ligands HL1 and HL2 and their corresponding complexes with Ni(II) and Co(II) ions were proposed based on the elemental analysis, infrared and 1H NMR spectral methods. Single crystal X-ray diffraction study of complex 1 revealed a distorted octahedral geometry around the metal ion provided by two units of the ligand. To explore the potential medicinal value of the new complexes, binding interaction of all the complexes with bovine serum albumin (BSA) was studied at normal physiological conditions using fluorescence and UV–Vis spectral techniques. The number of binding sites (n) and binding constant (Ka) were calculated according to the double logarithm regression equation. The results of synchronous fluorescence spectrum showed that binding of metal hydrazones with BSA induced conformational changes in BSA. The in vitro antioxidant and antimicrobial potentials of the new chelates were also carried out.Graphical abstractSynthesis and characterization of two new hydrazone complexes containing Ni(II) and Co(II) ions have been carried out. The interaction between metal(II) hydrazone chelates and bovine serum albumin (BSA) was followed by fluorescence and UV–Vis spectroscopy. Further, in vitro free radical scavenging and antimicrobial studies were also presented. Highlights► Synthesis of octahedral Ni(II) and Co(II) hydrazone complexes. ► Structural characterization using single crystal XRD. ► Electrochemistry of the synthesized complexes was studied using cyclic voltammetry. ► Interaction with protein, antioxidant and antimicrobial studies were carried out under in vitro conditions.

Three different samples of nickel aluminosilicate (NAS) nanocomposite for application as catalyst in transfer hydrogenation reactions were prepared by the incorporation of nickel nanoparticles into the mesoporous aluminosilicate framework obtained by a simple sol–gel method followed by calcinations at various temperatures without using any templates. The above prepared nanocomposites were characterized using thermal studies, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption–desorption (BET) analysis. Effect of calcination temperature of alumnosilicate support on the surface area and pore size of the nanocomposites was studied from BET analysis. Crystalline nature and particle size of nickel oxide present in the aluminosilicate framework was determined from powder XRD pattern. Surface morphology of the catalysts and their elemental compositions were obtained from SEM and EDAX techniques, respectively. Catalytic activity of the above prepared catalysts towards transfer hydrogenation (TH) of carbonyl compounds using isopropyl alcohol as hydrogen donor in presence of KOH was tested with wide range of carbonyl compounds. The yield of the products formed in TH reaction was monitored by gas chromatography (GC).Graphical abstractNickel aluminosilicate nanocomposite prepared by sol–gel technique was used for the transfer hydrogenation of carbonyl compounds.Highlights► Nickel aluminosilicate nanocomposites were prepared by sol–gel technique and characterized by various physiochemical techniques. ► Transfer hydrogenation of carbonyl compounds were carried out using the prepared catalyst. ► 2-Chloro-3-formyl quinoline and its derivatives were reduced to their corresponding alcohols in excellent yield.

Four new bivalent nickel hydrazone complexes have been synthesised from the reactions of [NiCl2(PPh3)2] with H2L {L = dianion of the hydrazones derived from the condensation of salicylaldehyde or o-hydroxy acetophenone with p-toluic acid hydrazide (H2L1) (1), (H2L2) (2) and o-hydroxy acetophenone or o-hydroxy naphthaldehyde with benzhydrazide (H2L3) (3) and (H2L4) (4)} and formulated as [Ni(L1)(PPh3)] (5), [Ni(L2)(PPh3)] (6), [Ni(L3)(PPh3)] (7) and [Ni(L4)(PPh3)] (8). Structural characterization of complexes 5–8 were accomplished by using various physico-chemical techniques. In order to study the influence of substitution in the ligand and its planarity on the biological activity of complexes 5–8 containing them, suitable hydrazone ligands 1–4 have been selected in this study. Single crystal diffraction data of complexes 5, 7 and 8 proved the geometry of the complexes to be distorted square planar with a 1:1 ratio between the metal ion and the coordinated hydrazones. To provide more insight on the mode of action of complexes 5–8 under biological conditions, additional experiments involving their interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) were monitored by UV-visible and fluorescence titrations respectively. Further, the ligands 1–4 and corresponding nickel(II) chelates 5–8 have been tested for their scavenging effect towards OH and O2− radicals. The effect of complexes 5–8 to arrest the growth of HeLa and Hep-2 tumour cell lines has been studied along with the cell viability against the non-cancerous NIH 3T3 cells under in vitro conditions.

Divalent Co, Ni and Cu hydrazone complexes containing [N′-(phenyl(pyridine-2-yl)methylidene) benzohydrazide] ligand were synthesised and characterised. Interactions of these complexes with DNA revealed an intercalative mode of binding between them. Further, all the hydrazone chelates showed moderate ability to cleave pUC19 DNA. Synchronous fluorescence spectra proved that the interaction of metal complexes with bovine serum albumin (BSA) resulted in a conformational change of the latter. Assay on the cytotoxicity of the above complexes against HeLa tumor cells and NIH 3T3 normal cells revealed that the complexes are toxic only against tumor cells but not to normal cells. In all the biological assays, the complex with copper ion as the metal center showed enhanced activities than the other two.Synthesis, structural elucidation and interaction with DNA, protein, cytotoxicity studies were carried out on biologically important transition metal hydrazone complexes.Highlights► Synthesis of new transition metal hydrazone complexes with octahedral geometry. ► All the new complexes showed significant interaction with both DNA and protein. ► Cytotoxicity results proved their efficacy against HeLa tumor cells.

Potential bidentate hydrazone ligands, HL1 (1) and HL2 (2) prepared by the condensation of benzaldehyde or furfuraldehyde with benzhydrazide upon reaction with [CuCl2(PPh3)2] yielded corresponding mononuclear complexes of the compositions [Cu(L1)(PPh3)2] (3) and [Cu(L2)(PPh3)2] (4). The exact nature of coordination of the hydrazones to the metal ion and the structure of the complexes were confirmed by spectral and single crystal X-ray diffraction studies. Interestingly, the reactions of 1 and 2 with [CuCl2(PPh3)2] resulted in the formation of the first structurally characterized copper(I) hydrazone complexes 3 and 4 along with the previously reported complex [CuCl(PPh3)3] 5 as a minor product in both the reactions. The metal complexes 3 and 4 showed significant binding towards calf thymus DNA (CT-DNA) via groove binding mode with binding constants in the magnitude 104–105 M− 1. In addition, the antioxidant activities of the complexes were also investigated through scavenging effect on DPPH, NO˙ and OH˙ radicals. The density functional theory calculations of complex 4 also supported the structure and stability of the reduced complex.The new complexes of [Cu(L1)(PPh3)2] (3) and [Cu(L2)(PPh3)2] (4) were synthesized, characterized and their theoretical and biological studies were carried out.Research Highlights► Synthesis of new copper(I) hydrazone complexes. ► Structural characterization involving single crystal XRD. ► DNA binding, antioxidant and DFT studies were carried out.

A novel method to prepare cadmium sulphide nanoparticles (CdS NPs) possessing nearly uniform size was adopted using eggshell membrane (ESM), under different pH conditions. Significant yield of CdS NPs with smallest possible size was obtained by increasing the pH of the reaction medium from acidic to alkaline. The above prepared CdS NPs have been characterized by UV–vis absorption as well as emission spectra, powder X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The efficiency of the above prepared CdS NPs as a catalyst for the photodegradation of toluidine blue (TB) dye, as a function of pH as well as the ratio between the catalyst and the substrate was studied after irradiation with UV light. The results showed that an efficient interaction took place between the catalyst and the substrate to cause degradation of the selected dye. A maximum degradation of toluidine blue dye (90%) was observed at pH 8 which is higher than that of the efficiencies at pH 4 and pH 6.Graphical abstractCadmium sulphide nanoparticles prepared through ESM showed efficient photocatalytic activity to degrade toluidine blue dye upon irradiation under UV light. The effect of pH on the photodegradation of the dye has been investigated and the maximum degradation was observed at pH 8.Research highlights► The work reported in this article involves a novel method to prepare CdS Nps. ► Effect of pH on the photocatalytic activity of CdS Nps to degrade TB dye was very significant. ► 90% of TB degradation was observed in the photodegradation experiment carried out at pH 8.

A new series of stable binuclear ruthenium(II) carbonyl complexes of the general formula [{RuX(CO)(EPh3)2}2L] (where X = H or Cl; E = P or As and L = dibasic tetradentate diacetyl resorcinol (H2-DAR)) have been synthesised by reacting ruthenium(II) starting complexes [RuHX(CO)(EPh3)3] (where X = H or Cl; E = P or As) and 4,6-diacetylresorcinol (H2-DAR) ligand in benzene medium. The structure of the new binuclear ruthenium(II) carbonyl complexes was established using elemental analysis, spectra (FT-IR, UV–vis and 1H NMR), electrochemical and thermal studies. In these reactions, the 4,6-diacetylresorcinol (H2-DAR) ligand behaves as a binegative tetradentate chelating ligand coordinating through O,O atoms of both the carbonyl and phenolic C–O groups by replacing a molecule of PPh3/AsPh3 and a hydride ion from the starting complexes. Further, all these complexes were also employed as new catalysts for the oxidation of primary and secondary alcohols in the presence of N-methylmorpholine-N-oxide (NMO) as a more viable co-oxidant. The free ligand and their metal complexes have also been screened for their antibacterial activity against the growth of gram +ve and gram −ve bacterial cultures.

•A review covering important aspects of electrospinning technique is presented.•Applications of nanofibers in various fields are reviewed.•Possibility to up-scale electrospinning technique to industry also included.Electrospinning (E-spin) is a unique technique to fabricate polymeric as well as metal oxide nanofibers. Research on electrospun nanofibers is a very active field in material science owing to their novel applications in diverse domains. The main focus of this review is to provide an insight into E-spin technique by understanding the working principle, influencing parameters and applications of nanofibers in different walks of life. Several hundreds of papers are published on the preparation, modification and applications of nanofibers produced by E-spin technique in the areas like sensor development, decontamination, energy storage, biomedical and catalysis etc. Details on the industrial scale development of E-spin technique, current scenario and future developments are also covered in this review.

A new series of geometrically different complexes containing ferrocenyl hydrazone ligands were synthesised by reacting suitable precursor complex [MCl2(PPh3)2] with the ligands HL1 or HL2 (where M = Cu(II) or Ni(II); HL1 = [Cp2Fe(CHN–NH –CO– C6H5)] (1) and HL2 = [Cp2Fe(CHN–NH–CO–C5H4N)]) (2). The new complexes of the composition [Cu(L1)(PPh3)2], (3) [Cu(L2)(PPh3)2] (4), [Ni(L1)2] (5) and [Ni(L2)2] (6) were characterised by various spectral studies. Among them, complexes 3 and 5 characterised by single crystal X-ray diffraction showed a distorted tetrahedral structure for the former with 1:1 metal–ligand stoichiometry, but a distorted square planar geometry with 1:2 metal–ligand stoichiometry in the case of the latter. Systematic biological investigations like DNA binding, DNA cleavage, protein binding, free radical scavenging and cytotoxicity activities were carried out using all the synthesised compounds and the results obtained were explained on the basis of structure–activity relationships. The binding constant (Kb) values of the synthesised compounds are found to be in the order of magnitude 103–105 M−1 and also they exhibit significant cleavage of supercoiled (SC) pUC19 DNA in the presence of H2O2 as co-oxidant. The conformational changes of bovine serum albumin (BSA) upon binding with the above complexes were also studied. In addition, concentration dependent free radical scavenging potential of all the synthesised compounds (1–6) was also carried out under in vitro conditions. Assays on the cytotoxicity of the above complexes against HeLa and A431 tumor cells and NIH 3T3 normal cells were also carried out.

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.

Three new bivalent nickel hydrazone complexes have been synthesised from the reactions of [NiCl2(PPh3)2] with H2L {L = dianion of the hydrazones derived from the condensation of o-hydroxynaphthaldehyde with furoic acid hydrazide (H2L1) (1)/thiophene-2-acid hydrazide (H2L2) (2)/isonicotinic acid hydrazide (H2L3) (3)} and formulated as [Ni(L1)(PPh3)] (4), [Ni(L2)(PPh3)] (5) and [Ni(L3)(PPh3)] (6). Structural characterization of these compounds 4–6 were accomplished by using various physico-chemical techniques. Single crystal X-ray diffraction data of complexes 4 and 5 proved their distorted square planar geometry. In order to ascertain the potential of the above synthesised compounds towards biomolecular interactions, additional experiments involving interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) were carried out. All the ligands and corresponding nickel(II) chelates have been screened for their scavenging effect towards O2−, OH and NO radicals. The efficiency of complexes 4–6 to arrest the growth of HeLa, HepG-2 and A431 tumour cell lines has been studied along with the cell viability test against the non-cancerous NIH 3T3 cells under in vitro conditions.

Synthesis, spectral, electrochemical and single crystal X-ray diffraction data of a new series of DMSO containing bivalent ruthenium hydrazone complexes are presented. XRD data of two of the new complexes revealed an octahedral coordination around the ruthenium ion satisfied by NOS2Cl2 atoms. Electrochemical studies showed the metal centred, quasi-reversible, one-electron redox behaviour of the new complexes. The binding of these complexes with biomolecules such as calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) protein investigated by different spectrophotometric methods revealed an intercalative mode of interaction. The in vitro cytotoxicity of these complexes evaluated by the MTT assay on a panel of cancer and normal cell lines indicated that the above complexes are more toxic to cancer cells with a few micromolar concentrations as the IC50 value, but are significantly less toxic to normal cell lines. The observed variations in the binding interactions and cytotoxicity of the complexes were attributed to the nature of the hydrazide moiety of the hydrazones that influences their biological activities.

A new set of penta-coordinated copper(II) hydrazone complexes containing solvated methanol were synthesized by reacting the hydrazone ligands, 2-acetylpyridine benzoyl hydrazone (HL1) and 2-acetylpyridine thiophene-2-carboxylic acid hydrazone (HL2), with [CuCl2(DMSO)2] and characterized by different spectral methods. Single crystal X-ray diffraction studies of the complexes revealed that both of them, [CuCl(L1)(MeOH)] (1) and [CuCl(L2)(MeOH)] (2), have square pyramidal geometry around the cupric ion, in which the hydrazone is coordinated through NNO atoms along with a molecule of methanol in the apical position. Interaction of the ligands HL1 and HL2 along with the corresponding copper complexes 1 and 2 with calf thymus DNA (CT-DNA) has been estimated by absorption and emission titration methods which revealed that the compounds interacted with CT-DNA through intercalation. Binding of the compounds, i.e., free ligands and complexes (1) and (2) with bovine serum albumin (BSA) protein investigated using UV-visible, fluorescence and synchronous fluorescence spectroscopic methods indicated that there occurred strong binding of copper complexes to BSA over the ligands. Further, the cytotoxicity of the compounds examined in vitro on a panel of cancerous cell lines such as a human cervical cancer cell line (HeLa), a pancreatic cancer cell line (PANC-1), an Ehrlich ascites cancer cell line (EAC) and Dalton's lymphoma ascitic cancer cells (DLA) and a normal mouse embryonic fibroblasts cell line (NIH3) demonstrated that the complexes 1 and 2 possessed superior cytotoxicity than that of well-known commercial anticancer drug cisplatin to the tumor cells but are less toxic to the normal cell line and have emerged as potential candidates for further studies.

A set each of new bivalent and trivalent ruthenium complexes, [RuIII(HL)Cl2(EPh3)2] and [RuII(L)(CO)(EPh3)2] (E = P (complexes 1 and 2) or As (complexes 3 and 4)) were synthesised from the reactions of [RuIIICl3(EPh3)3] with 2-hydroxynaphthaldehyde benzoic acid hydrazone (H2L) in methanol–chloroform and characterized by elemental analysis, spectral data and XRD study. A suitable mechanism to account for the formation of bivalent ruthenium carbonyl complexes from the corresponding trivalent precursors is provided by considering the role of added base in the reaction. Interaction of complexes 1–4 with CT-DNA/bovine serum albumin was analysed with absorption and emission spectral titration studies. In vitro cytotoxic potential of the above ruthenium hydrazone complexes 1–4 assayed against the A549 cell line revealed a significant growth inhibition. The test complexes 1–4 added in IC50 concentration into the cell culture medium enhanced the release of lactate dehydrogenase, NO and reactive oxygen species in comparison with the control. Cell death induced by the complexes was studied using a propidium iodide staining assay and showed noticeable changes in the cell morphology which resembled apoptosis.

Four new bivalent nickel hydrazone complexes have been synthesised from the reactions of [NiCl2(PPh3)2] with H2L {L = dianion of the hydrazones derived from the condensation of salicylaldehyde or o-hydroxy acetophenone with p-toluic acid hydrazide (H2L1) (1), (H2L2) (2) and o-hydroxy acetophenone or o-hydroxy naphthaldehyde with benzhydrazide (H2L3) (3) and (H2L4) (4)} and formulated as [Ni(L1)(PPh3)] (5), [Ni(L2)(PPh3)] (6), [Ni(L3)(PPh3)] (7) and [Ni(L4)(PPh3)] (8). Structural characterization of complexes 5–8 were accomplished by using various physico-chemical techniques. In order to study the influence of substitution in the ligand and its planarity on the biological activity of complexes 5–8 containing them, suitable hydrazone ligands 1–4 have been selected in this study. Single crystal diffraction data of complexes 5, 7 and 8 proved the geometry of the complexes to be distorted square planar with a 1:1 ratio between the metal ion and the coordinated hydrazones. To provide more insight on the mode of action of complexes 5–8 under biological conditions, additional experiments involving their interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) were monitored by UV-visible and fluorescence titrations respectively. Further, the ligands 1–4 and corresponding nickel(II) chelates 5–8 have been tested for their scavenging effect towards OH and O2− radicals. The effect of complexes 5–8 to arrest the growth of HeLa and Hep-2 tumour cell lines has been studied along with the cell viability against the non-cancerous NIH 3T3 cells under in vitro conditions.