Ru(II)–DMSO complexes containing aromatic and heterocyclic acid hydrazides: Structure,electrochemistry and biological activity

The reaction of cis-[RuCl₂(DMSO)₄] with a family of aromatic and heterocyclic acid hydrazides yielded new complexes of the general formula trans-[RuCl₂(DMSO)₂(hydrazide)] · nH₂O (n = 0; 1–6; n = 1; 7). The new complexes have been characterized by IR, UV–Vis and ¹H NMR spectroscopic methods. In addition, the structure of one of the complexes, [RuCl₂(DMSO)₂(tcah)] · H₂O (tcah = thiophene-2-carboxylic acid hydrazide), has been determined by single crystal X-ray diffraction. All the studies reveal the neutral bidentate coordination of the hydrazide ligands through the acyl oxygen and amine nitrogen atoms. The electron transfer properties of the complexes were studied by cyclic voltammetry and all the complexes except one show an irreversible/quasi-reversible reduction wave (Ru^II/Ru^I) and an uncoupled oxidation peak (Ru^III/ Ru^II). The preliminary DNA-binding ability of the complexes, studied with herring sperm DNA, shows the binding of the complexes with DNA with a lesser affinity than classical intercalators. The complexes have also been screened for their antibacterial activity against five pathogenic bacteria.     

Synthesis,characterization and antimalarial activity of new iridium–chloroquine complexes

Chloroquine base (CQ) reacts with [Ir(COD)Cl]₂ and IrCl₃ · 3H₂O to yield of Ir(CQ)Cl(COD) (1) and Ir₂Cl₆(CQ) · 3H₂O (2), respectively. Reaction of [Ir(COD)Cl]₂ with CQ in the presence of NH₄PF₆ leaded to [Ir(CQ)(Solv)₂]PF₆ (3). The three new iridium–CQ complexes were characterized by a combination of elemental analysis, IR and NMR spectroscopies and evaluated in vitro against Plasmodium beghei. Comparison of the IC₅₀ values obtained with the experimental compounds with that determined for chloroquine diphosphate indicated a higher activity for complex 2, while complexes 1 and 3 showed a similar and lower activity, respectively.     

Nanosized silver–palm pollen nanocomposite,green synthesis,characterization and antimicrobial activity

Palm pollen (PP) has been widely used in nutrition, pharmaceutical and cosmetic industries. In the present study, we explored the potential of PP in the synthesis of a silver nanoparticle (Ag NP). PP was used as both reducing and stabilizing agent. The Ag/PP nanocomposite was examined by field emission electron microscopy, X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet spectroscopy and zeta potential measurement. The biosynthesized NPs showed surface plasmon resonance centered at 425 nm with an average particle size measured to be 23 nm and a zeta potential of ?30.9 mV. Prominent FT-IR signals were obtained and ascribed to phenolic and carbohydrate compounds involved in the formation of the Ag NPs, and proteins which participated in stabilization of the Ag NPs. The biologically synthesized Ag NPs were found to be extremely effective against E. coli (13.8 ± 0.25 mm) with a minimum inhibitory concentration of 20 µg/mL. Thus, such biosynthesized Ag NPs can be used in medicinal applications.     

Mononuclear copper(I) complexes with triphenylphosphine and N,N′-disubstituted thioureas: synthesis,characterization, and biological evaluation

Abstract

Twelve new complexes, of the general formula CuCl(TPP)₂Tu^1–12 (Tu?=?thiourea), were synthesized by the reaction of CuCl(TPP)₃ (TPP?=?triphenylphosphine) and various N,N′-disubstituted thioureas. The structures of the synthesized complexes were characterized by different techniques such as Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy (¹H, ¹³C, ³¹P, and ¹⁹F), and the representative complexes (1, 2 and 12) were analyzed via single crystal X-ray diffraction. The single crystal X-ray analysis revealed that copper(I) is coordinated with chlorine, two TPP, and the thiourea ligands through the sulfur atom in a mononuclear distorted tetrahedral mode. The compounds were tested for antibacterial, antifungal, cytotoxicity, antileishmanial, and antioxidant activities. The results showed that the synthesized complexes are significantly more active than the free ligands and the commercial reference compounds. The high biological activities of the complexes versus free ligands can be attributed to the copper(I) chloride complexation with thiourea ligands. The synthesized complexes were also evaluated, both experimentally and theoretically, for DNA binding studies. The UV-visible spectroscopic and molecular docking studies demonstrated that the complexes are conjugating with DNA through a groove binding mode.     

Design,synthesis,characterization,cytotoxic and structure activity relationships of novel Ru(Ⅱ) complexes

Platinum containing compounds have shown antineoplastic potential, but their clinical applications have been limited by high toxicity. Ruthenium containing complexes have long been known to be well suited for biological applications, and have long been utilized as replacements to popular platinum based-drugs. Here, we report a novel series of ruthenium(II) arene compounds bearing thiosemicarbazone and isonicotinylhydrazone ligands with potent anticancer activity their structure activity relationships and apoptosis was studied. The cytotoxic activity of the new ruthenium(II) arene compounds has been evaluated in several cell lines (Molt 4/C8, L1210, CEM, HL60 and BEL7402). Among them, ten complexes were found to be excellent in vitro growth inhibitory activity against various cell lines with IC50 in the sub-micromolar range.     

Transition metal complexes constructed by pyridine–amino acid: fluorescence sensing and catalytic properties

Transition Metal Chemistry - Four amino acid Schiff base complexes—one with a 3D network structure ({[Cd2(PYSA)2(H2O)]·3H2O}n (1)) and the other three with a supramolecular network...     

Phenanthroline–dipyrromethene conjugates: synthesis,characterization, and spectroscopic investigations

Mono- and tri-topic ligands, based on dipyrromethenes and the 1,10-phenanthroline nucleus, as well as BF₂ complexes derived thereof are described. While BODIPY 12 has been X-ray crystallographically characterized, the structural features of the free ligands 9 and 10 may render them useful as precursors for the elaboration of novel supramolecular architectures.     

Preparation, characterization and pharmacodynamic activity of supramolecular and colloidal systems of rosuvastatin–cyclodextrin complexes

In the present study influence of nature of selected cyclodextrins (CDs) and of methods of preparation of drug–CD complexes on the oral bioavailability, in vitro dissolution studies and pharmacodynamic activity of a sparingly water soluble drug rosuvastatin (RVS) was investigated. Phase solubility studies were conducted to find the interaction of RVS with β-CD and its derivatives, which indicated the formation of 1:1 stoichiometric inclusion complex. The apparent stability constant (K_1:1) calculated from phase solubility diagram were in the rank order of β-CD < hydroxypropyl-β-cyclodextrin (HP-β-CD) < randomly methylated-β-cyclodextrin (RM-β-CD). Equimolar drug–CD solid complexes prepared by different methods were characterized by the Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). FTIR study demonstrated the presence of intermolecular hydrogen bonds and ordering of the molecule between RVS and CDs in inclusion complexes. DSC and XRD analysis confirmed formation of inclusion complex by freeze dried method with HP-β-CD and RM-β-CD. Aqueous solubility and dissolution studies indicated improved dissolution rates of prepared complexes in comparison with drug alone. Moreover, CD complexes demonstrated of significant improvement in reducing total cholesterol and triglycerides levels as compared to pure drug. However the in vivo results only partially agreed with those obtained from phase solubility studies.     

Antioxidant activity of bovine serum albumin binding amino acid Schiff-bases metal complexes

Glutamic acid-salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin (BSA),which afforded BSA binding Schiff-base metal complexes (BSA-SalGluM,M=Cu,Co,Ni,Zn).The BSA binding metal complexes were characterized by UV-vis spectra and Native PAGE.It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes.The effect of the antioxidant activity was investigated.The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.     

Catecholato complexes of palladium(II)–naphthylazoimidazoles: synthesis,spectral characterization,electrochemistry and solvatochromic studies

[Pd(-NaiR)(O,O)] [-NaiR = 1-alkyl-2-(naphthyl--azo)imidazoles; R = Me (a), Et (b), CH₂Ph (c) and O,O = pyrocatecholato (cat) (3), 4-t-butylcatecholato (tbcat) (4), 3,5-di-t-butylcatecholato (dtbcat) (5), and tetracholorocatecholato (tccat) (6)] complexes were characterized by elemental analyses, i.r. and ¹H-n.m.r. spectral data. Studies by cyclic voltammetry suggest the existence of two redox couples, positive saturated calomel electrode (s.c.e.) that are due to catecholes to semiquinone, and semiquinone to quinone oxidations, respectively; two couples at negative to s.c.e. are associated with azo reductions. The complexes exhibit ligand-to-ligand charge-transfer transition in the near-i.r. region. The band position is largely dependent upon the substituent on the catechole frame and exhibits a negative solvatochromic effect. The transition is qualitatively assigned to the HOMO (cat) LUMO (-NaiR) transition.     

Stabilized catalyst comprising nickel and supported 12-tungstophosphoric acid: synthesis,characterization and aqueous-phase Suzuki–Miyaura cross-coupling

Transition Metal Chemistry - This work describes a simple impregnation and soaking method for designing of stabilized nickel exchanged supported 12-tungstophosphoric acid, its characterization and...     

Total synthesis of (−)-vitrenal and its biological activity

(−)-Vitrenal, the enantiomer of a natural sesquiterpene aldehyde isolated from a liverwort, has been synthesized starting from (+)-Δ³-carene, and its activity as a plant-growth regulator has been tested.     

New planar trans-copper(II) β-dithioester chelate complexes: synthesis,characterization, anticancer activity and DNA-binding/cleavage studies

New planar trans-copper(II) β-dithioester complexes, [Cu(L)₂] (L = methyl-3-hydroxy-(3-pyridyl)-2-propenedithioate (L1 in 1), methyl-3-hydroxy-(2-naphthyl)-2-propenedithioate (L2 in 2), methyl-3-hydroxy-3-(p-methoxyphenyl)-2-propenedithioate (L3 in 3), methyl-3-hydroxy-3-(p-fluorophenyl)-2-propenedithioate (L4 in 4), and methyl-3-hydroxy-3-(p-bromophenyl)-2-propenedithioate (L5 in 5)), have been synthesized and characterized by elemental (C, H, N and S) analysis, ESI-MS, IR, and UV-vis spectra. The structures of HL3 and its corresponding complex 3 have been determined by X-ray crystallography. Electrochemical behavior of all complexes has been studied by cyclic voltammetry. All five planar complexes show efficient DNA-binding and DNA (PBR322)-cleavage in a concentration-dependent manner (1 > 3 > 5 > 2 > 4). Cleavage efficiency is enhanced in the presence of H₂O₂ as well as ascorbic acid. However, the order of increased efficiency of Cu(II) chelates differs in the presence of H₂O₂ as 4 > 1 > 2 > 3 > 5. Among these complexes, the pyridyl- and methoxy-functionalized 1 and 3 have shown higher self-activating capability in DNA-cleavage. All complexes show significant variation in IC₅₀ on MCF-7 cell line. Additionally, treatment with the complexes gradually increases apoptotic cell death in dose-dependent manner in RAW 264.7 cell line. These findings highlight potential cancer protective nature of these complexes.     

Copper complexes of pyridyl–tetrazole ligands with pendant amide and hydrazide arms: synthesis,characterization, DNA-binding and antioxidant properties

Pyridyl–tetrazole ligands 2-(5-(pyridin-2-yl)-1H-tetrazol-1-yl)acetamide (L1), 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetamide (L2), 2-(5-(pyridin-2-yl)-1H-tetrazol-1-yl)acetohydrazide (L3) and 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetohydrazide (L4) have been prepared and coordinated with CuCl₂·2H₂O to furnish the corresponding complexes [Cu(L1) ₂ ]–[Cu(L4) ₂ ]. EPR spectra of the complexes are characteristic of square planar geometries, with nuclear hyperfine spin 3/2. DNA-binding studies using UV–Vis absorption spectroscopy, viscosity and thermal denature studies revealed that all of these complexes are avid binders of calf thymus DNA. The antioxidant properties of the free ligands and the Cu(II) complexes were investigated using the p-nitrosodimethyl aniline hydroxyl radical scavenging method, and [Cu(L4) ₂ ] was found to show the highest activity.     

New saccharinate complexes with 3,3′-azobispyridine ligand: synthesis,characterization, and spectroscopic properties

The new metal complexes with saccharinate (sac) and 3,3′-azobispyridine (3,3′-abpy), [Ni(H₂O)₄(3,3′-abpy)₂](sac)₂ (1), [Cu(sac)₂(H₂O)(μ-3,3′-abpy)]_n (2), [Zn(H₂O)₄(3,3′-abpy)₂](sac)₂ (3), [Cd(sac)₂(H₂O)₂(μ-3,3′-abpy)]_n (4), and [Hg₂(μ-sac)₂(sac)₂(μ-3,3′-abpy)(3,3′-abpy)₂]_n (5), were synthesized and characterized by IR spectra, elemental analysis, and single-crystal X-ray diffraction. Spectroscopic (UV–vis and photoluminescence) and thermal properties were also investigated. Single-crystal X-ray analysis reveals that Ni(II) and Zn(II) are coordinated by four aqua ligands and two nitrogens of 3,3′-abpy, while sac is a counter-ion in 1 and 3. In 2, Cu(II) and all ligands are linked by coordination bonds and 3,3′-abpy ligands connect the Cu(II) centers forming a 1-D coordination polymer. In 4, sac N-coordinated to Cd(II) and distorted octahedral geometry of Cd(II) ion is completed by two aqua and bridging 3,3′-abpy ligands. In 5, sac bridges two Hg(II) ions to generate dinuclear [Hg₂(μ-sac)₂] units. These dinuclear units are connected by 3,3′-abpy to form a 1-D coordination polymer. The photoluminescence spectra of 3 and 5 show blue fluorescent emission bands, and these emissions can probably be assigned to intraligand fluorescent emissions. Thermal decompositions of the compounds are also discussed. For all complexes, magnetic susceptibility measurements show expected magnetic behavior.     

Mixed ligand complexes of β-diketonates: synthesis,characterization, and FAB mass spectral analysis

Complexes of the type MLL′ · nB (where M = Ni(II) and Cu(II); LH and L′H = 2,4-pentanedione (acacH), 1-phenyl-1,3-butanedione (bacH), and 1,3-diphenyl-1,3-propanedione (dbmH); n = 0 to 2 and B = water or pyridine) have been synthesized and characterized. IR spectra are consistent with uninegative bidentate ligands. Magnetic moments and electronic spectral studies reveal high-spin octahedral geometry for nickel(II) complexes and distorted octahedral stereochemistry for copper(II) complexes. Frozen chloroform solution ESR spectra of the copper(II) complexes display significant Jahn–Teller distortion and dimeric behavior of the complexes in solution. FAB mass spectra of the copper(II) complexes also exhibit peaks corresponding to dimers. Molecular, pseudo-molecular, dimeric pseudo-molecular, and fragment ion peaks in unit resolution mass spectra have been identified with the help of their isotope distribution pattern expected due to natural abundances of the ⁶³Cu and ⁶⁵Cu isotopes. All the FAB mass spectral peaks from the fragment ions containing copper have been interpreted on the basis of isotope distribution pattern.     

Synthesis,characterization and biological activity of copper(II) complexes with ligands derived from β-amino acids

Transition Metal Chemistry - Two copper(II) complexes with ligands derived from β-amino acids, 2-(1-aminocyclohexyl)acetic acid L1 and 2-(1-amino-4-(tert-butyl)cyclohexyl)acetic acid L2, were...     

Synthesis and characterization of organotitanium substituted heteropolytungstosilicates and their biological activity

Tris-, di-(organotitanium) substituted tungstosilicates α、β-[(CpTi)3(SiW9O37)]7- and γ-[(Cp-Ti)2(SiW10O38)]6- were prepared by the reaction of Cp2TiCl2 (Cp = η5-C5H5) with α、β-SiW9O349- (noted α、β-SiW9), γ-SiWO368- (noted γ-SiW10) . The products were characterized by means of elemental analysis, IR, 1H NMR, 183W NMR and polarography. 183W NMR spectra of the complexes support the stoichiometry of the new heteropolyanions and the probable retention of the A-XWg or γ-SiW10 units. And the organotitanium substituted compounds showed promising in vitro antitumor activity in two of human tumor cell lines.