Showing papers on "Hydrazone published in 2012"

A novel water soluble ligand bridged cobalt(II) coordination polymer of 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (isonicotinic) hydrazone: evaluation of the DNA binding, protein interaction, radical scavenging and anticancer activity.

Abstract: A novel water soluble ligand-bridged cobalt(II) coordination polymer has been synthesized by reacting the new ligand, 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (isonicotinic) hydrazone (H2L) with Co(NO3)2·6H2O and characterized by spectral, analytical and structural methods. Single crystal X-ray diffraction studies revealed that the Co(II) complex, {[Co(H2L)(H2O)2](NO3)2·3H2O}n has a slightly distorted octahedral geometry around the central Co(II) ion; the ligand is coordinated through the ONO donor atoms to one Co(II) metal center and bridged through the pyridine nitrogen atom to another similar Co(II) center so as to form a one-dimensional polymeric unit. The interaction of the ligand and the complex with calf thymus DNA (CT-DNA) has been explored by absorption and emission titration methods, which revealed that the compounds could interact with CT-DNA through intercalation. The interactions of the compounds with bovine serum albumin (BSA) were also investigated using UV–visible, fluorescence and synchronous fluorescence spectroscopic methods. The results indicated that the complex exhibited a strong binding to BSA over the ligand. Investigation of the antioxidative properties showed that the polymeric Co(II) complex has a strong radical scavenging potency against hydroxyl radicals, 2,2-diphenyl-1-picrylhydrazyl radicals, nitric oxide and superoxide anion radicals. Further, the cytotoxic effect of the compounds examined on cancerous cell lines, such as human cervical cancer cells (HeLa), human laryngeal epithelial carcinoma cells (HEp-2), human liver carcinoma cells (Hep G2), human skin cancer cells (A431) and non-cancerous NIH 3T3 mouse embryonic fibroblasts cell lines showed that the complex exhibited substantial anticancer activity.

Hydrazone as the Directing Group for Ir-Catalyzed Arene Diborylations and Sequential Functionalizations

Abstract: The use of hemilabile pyridine–hydrazone N,N-ligands allows the highly selective Ir-catalyzed ortho,ortho′-directed diborylation of aromatic N,N-dimethylhydrazones in near-quantitative yields. One-pot sequential Suzuki–Miyaura cross-coupling with different aryl bromides provides a short entry to unsymmetrically substituted 2,6-diarylbenzaldehyde derivatives.

Synthesis of novel heterobimetallic copper(I) hydrazone Schiff base complexes: A comparative study on the effect of heterocyclic hydrazides towards interaction with DNA/protein, free radical scavenging and cytotoxicity

Abstract: 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.

Azo-hydrazone tautomerism observed from UV-vis spectra by pH control and metal-ion complexation for two heterocyclic disperse yellow dyes

Abstract: The azo-hydrazone tautomerism of two pyridine-2,6-dione based Disperse Yellow dyes has been achieved by pH control and metal-ion complexation, respectively, which is evidenced by UV-visible spectra using pH-titration, 1H NMR and X-ray single-crystal diffraction techniques for two dyes and one neutral dinuclear dye–metal complex. pH-titration experiments under strong and weak acidic conditions (HCl and HOAc) as well as strong and weak alkaline conditions (NaOH and ammonia) demonstrate that there is an equilibrium between the azo (HL1-A and HL2-A) and hydrazone (HL1-H and HL2-H) tautomers for two dyes in solution but the hydrazone form is dominant under conventional conditions. The hydrazone proton is also observed in the 1H NMR spectra of HL1-H and HL2-H which can be verified by the hydrogen–deuterium exchange and the presence of cooperative six-membered intramolecular hydrogen rings involving the hydrazone proton in their X-ray single-crystal structures. Moreover, the azo-hydrazone tautomerism is evidenced by the formation of a novel neutral dinuclear dye–metal complex Cu2(L2-A)4, where all the ligands are in the azo form and two types of coordination modes are present for four L2-A ligands. Namely, the side two ligands serve as the bidentate capping ligands, while the middle ones act as the quadridentate bridging ligands linking adjacent CuII centers in a reverse fashion.

Phosphino Hydrazones as Suitable Ligands in the Asymmetric Suzuki–Miyaura Cross-Coupling

Abstract: Phosphino hydrazones derived from C2-symmetric hydrazines exhibit excellent catalytic activity and provide good enantioselectivities in the asymmetric Suzuki–Miyaura cross-coupling to axially chiral biaryls, in particular for the most challenging reactions of monocyclic, functionalized aryl bromides and triflates. X-ray analysis of preformed [Pd(P/N)Cl2] precatalysts [(P/N) = phosphino hydrazone] revealed a strong n–π conjugation in the hydrazone moiety, identified by a high planarity degree at the pyrrolidine N(sp3) atom, that makes rotations around N–N bonds inconsequential. The complexes are also characterized by an envelope-like conformation with the Pd atom placed at the opposite side to the 2-phenyl group on the nearest stereogenic center of the pyrrolidine group. The isolation and structural analysis of oxidative addition intermediates indicate that the configurational stability of Pd–C(Ar) bonds is dependent on the substitution pattern in the aryl bromide.

Asymmetric formal carbonyl-ene reactions of formaldehyde tert-butyl hydrazone with α-keto esters: dual activation by bis-urea catalysts.

Abstract: The dual activation of α-keto esters and formaldehyde tert-butyl hydrazone by BINAM-derived bis-ureas is the key to achieve high reactivity and excellent enantioselectivities in nucleophilic addition (formal carbonyl-ene reaction) to functionalized tertiary carbinols. Ensuing high-yielding diazene-to-aldehyde tranformations and subsequent derivatizations provides a direct entry to a variety of densely functionalized products.

Structure–activity relationship study of copper(II) complexes with 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (4′-methylbenzoyl) hydrazone: synthesis, structures, DNA and protein interaction studies, antioxidative and cytotoxic activity

Abstract: Novel 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (4′-methylbenzoyl) hydrazone (H2L) (1) and its two copper(II) complexes have been synthesized Single-crystal X-ray diffraction studies revealed that the structure of the new copper(II) chloride complex, [Cu(H2L)Cl2]·2H2O (2), is square pyramidal and that of the copper(II) nitrate complex, [Cu(HL)NO3]·DMF (3), is square planar In 2, the copper atom is coordinated by the ligand with ONO donor atoms, one chloride ion in the apical position, and the other chloride in the basal plane In 3, the ligand coordinates as a uninegative tridentate ONO− species and with one nitrate ion in the basal plane DNA binding experiments indicated that the ligand and copper(II) complexes can interact with DNA through intercalation Bovine serum albumin binding studies revealed that the compounds strongly quench the intrinsic fluorescence of bovine serum albumin through a static quenching process Antioxidative activity tests showed that 1 and its copper(II) complexes have significant radical scavenging activity against free radicals Cytotoxic activities of the ligand and copper(II) complexes showed that the two copper(II) complexes exhibited more effective cytotoxic activity against HeLa and HEp-2 cells than the corresponding ligand The entire biological activity results showed that the activity order was 1 < 2 < 3

Lanthanide complexes of tritopic bis(hydrazone) ligands: single-molecule magnet behavior in a linear Dy(III)3 complex.

Abstract: Tritopic pyridinebis(hydrazone)-based ligands typically produce square M(9) [3 × 3] grid complexes with first-row transition-metal ions (e.g., M = Mn, Fe, Co, Cu, Zn), but with larger lanthanide ions, such coordination motifs are not produced, and instead linear trinuclear complexes appear to be a preferred option. The reaction of 2pomp [derived from pyridine-2,6-bis(hydrazone) and 2-acetylpyridine] with La(III), Gd(III), and Dy(III) salts produces helical linear trinuclear [Ln(3)(2pomp)(2)]-based complexes, where each metal ion occupies one of the three tridentate ligand pockets. Two ligands encompass the three metal ions, and internal connections between metal ions occur through μ-O(hydrazone) bridges. Coligands include benzoate, nitrate, and N,N-dimethylformamide. The linear Dy(III)(3) complex exhibits single-molecule magnet behavior, demonstrated through alternating-current susceptibility measurements. Slow thermal magnetic relaxation was detected in an external field of 1800 Oe, where quantum-tunneling effects were suppressed (U(eff) = 14 K).

Variation in the Biomolecular Interactions of Nickel(Ii) Hydrazone Complexes Upon Tuning the Hydrazide Fragment

Abstract: 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.

Enantioselective conjugate addition of donor-acceptor hydrazones to α,β-unsaturated aldehydes through formal diaza-ene reaction: access to 1,4-dicarbonyl compounds.

Abstract: Donor–acceptor monosubstituted hydrazones participate as suitable reagents able to undergo an enantioselective formal diaza–ene reaction with α,β-unsaturated aldehydes under chiral secondary amine catalysis. This constitutes a new approach for the enantioselective conjugate addition of hydrazones to enals under metal-free conditions and leads to the formation of γ-hydrazono carboxylic acids after oxidation/[1,3]-H shift. The methodology is also useful for the synthesis of enantioenriched β-substituted α-keto-1,5-diesters by using the hydrazone moiety as a masked carbonyl group.

A Tunable Route for the Synthesis of Azomethine Imines and β-Aminocarbonyl Compounds from Alkenes

Abstract: Cyclic azomethine imines possessing a β-aminocarbonyl motif are accessed from simple alkene and hydrazone starting materials. A thermal, concerted alkene aminocarbonylation pathway involving an imino-isocyanate intermediate is proposed and supported by DFT calculations. A notable feature of the process is the steric shielding present in the dipoles formed, which allows for facile purification of the products by chromatography or crystallization. In addition, a fluorenone-derived reagent is reported, which provides reactivity with several alkene classes and allows for mild derivatization of the dipoles into β-aminoamides, β-aminoesters, and β-amino acids.

Synthesis and Biological Evaluation of Some Hydrazone Derivatives as Anti-inflammatory Agents

Abstract: In the present study, some hydrazone derivatives were synthesized via the reaction of 3-cyclohexylpropionic acid hydrazide with various benzaldehydes. The chemical structures of the compounds were elucidated by spectroscopic techniques such as IR, 1 H-NMR and FAB-MS and elemental analyses. The compounds were evaluated for their anti- inflammatory and cytotoxic activities. Anti-inflammatory activity was determined in terms of inhibition of NF-! B, ROS generation and iNOS activity. Several derivatives inhibited NF-! B and iNOS, but no effect was observed on intracellular ROS generation. Furthermore no cytoxicity was observed. Biological activity compared with the chemical structural information suggests that different functional groups on the phenyl ring influence the physicochemical properties and thus modulate biological activity.

Synthesis and antioxidant activity evaluations of melatonin-based analogue indole-hydrazide/hydrazone derivatives

Abstract: Melatonin (MLT) is a hormone synthesized from the pineal gland. It is a direct scavenger of free radicals, which is related to its capability to defend cells from oxidative stress. Recently MLT-related compounds are under investigation to establish which exhibit the maximum activity with the lowest side effects. In this study 5-chloroindole hydrazide/hydrazone derivatives were synthesized from 5-chloroindole-3-carboxaldehyde and phenyl hydrazine derivatives. All the compounds characterized and in vitro antioxidant activity was investigated against MLT and BHT. Most of the compounds showed strong inhibitory effect on the superoxide radical scavenging assay at 1 mM concentration (79 to 95%). Almost all the tested compounds possessed strong scavenging activity against the DPPH radical scavenging activity with IC50 values (2 to 60 µM). Lastly, compound 1j revealed stronger inhibitory activity against MLT in the LP inhibitory assay at 0.1mM concentration (51%) while the rest of the compounds showed moderate in...

Nickel and cobalt complexes of benzoic acid (2-hydroxy-benzylidene)-hydrazide ligand: synthesis, structure and comparative in vitro evaluations of biological perspectives

Abstract: 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.

Synthesis and antibacterial activity against ralstonia solanacearum for novel hydrazone derivatives containing a pyridine moiety

Abstract: Ralstonia solanacearum, one of the most important bacterial diseases on plants, is a devastating, soil-borne plant pathogen with a global distribution and an unusually wide host range. In order to discover new bioactive molecules and pesticides acting on tobacco bacterial wilt, we sought to combine the active structure of hydrazone and pyridine together to design and synthesize a series of novel hydrazone derivatives containing a pyridine moiety. A series of hydrazone derivatives containing a pyridine moiety were synthesized. Their structures were characterized by 1 H-NMR, 13 C-NMR, IR, and elemental analysis. The preliminary biological activity tests showed that compound 3e and 3g exhibited more than 80% activity against Ralstonia solanacearum at 500 mg/L, especially compound 3g displayed relatively good activity to reach 57.0% at 200 mg/L. A practical synthetic route to hydrazone derivatives containing a pyridine moiety by the reaction of intermediates 2 with different aldehydes in ethanol at room temperature using 2-chloronicotinic acid and 2-amino-5-chloro-3-methylbenzoic acid as start materials is presented. This study suggests that the hydrazone derivatives containing a substituted pyridine ring could inhibit the growth of Ralstonia solanacearum.

Syntheses, crystal structures, and catalytic properties of dioxomolybdenum(VI) complexes with hydrazone ligands

Abstract: Two new dioxomolybdenum(VI) complexes, [MoO2L1(CH3OH)] (1) and [MoO2L2(H2O)] (2), where L1 and L2 are dianionic form of N′-(2-hydroxy-3-methoxybenzylidene)-4methoxybenzohydrazide and N′-(2-hydroxy-3methoxybenzylidene)-2-hydroxybenzohydrazide, respectively, have been synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray determination. The complexes are mononuclear molybdenum(VI) compounds. Mo in each complex is octahedral. The difference in the substituent groups in the benzohydrazides leads to coordination of different solvent molecules. Crystals of the complexes are stabilized by hydrogen bonds. The complexes are effective catalysts for sulfoxidation.