Ratiometric Interactions of Anionic Surfactants with Calf Thymus DNA Bound Cationic Surfactants: Study II

Cationic surfactant cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) bind to the calf thymus DNA (ct‐DNA) like anionic biopolymers electrostatically, and establish equilibrium in aqueous medium at pH 7. At low concentration, ct‐DNA does not interact with anionic surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzylsulfonate (SDBS). However, in the ground state, anionic surfactant is found to clearly establish equilibrium with ct‐DNA‐bound cationic surfactant whereby the same surfactant–DNA isosbestic point reappears. We herein report a detail ratiometric binding of CPB with ct‐DNA, and interaction of anionic SDBS with DNA‐bound CPB in comparison with the combined ct‐DNA–CTAB–SDS system. Compaction of ct‐DNA in presence of CPB and its decompaction using anionic SDBS is also studied in comparison with CTAB–SDS combination. The techniques used are tensiometry, spectrophotometry, viscometry, cyclic voltammetry, circular dichroism, isothermal titration calorimetry, and density functional theory (DFT)‐based computational calculations. The size and surface charge density of the surfactant headgroups and the phosphate group in DNA have a contributing role in the DNA compaction–decompaction phenomenon.     

Synthesis, Characterisation and Anti-Fungal Activities of Some New Copper(II) Complexes of Octamethyl Tetraaza-Cyclotetradecadiene

The ligand Me(8)[14]diene, L, in its free state as well as in the dihydroperchlorate form, L.2HClO(4), coordinates copper(ll) in different salts to yield a series of [CuLX(x)] X(y)(H(2)O)(z) complexes where X = NO(3), ClO(4), NCS, Cl and Br; x and y may have values of 0 or 2 and z = 0, 1 or 2. The complex, [CuL(ClO(4))(2)].2H(2)O is found to undergo axial ligand substitution reactions with SCN(-), NO(3) and Cl(-) to give a variety of substitution derivatives: [CuL(ClO(4))(m) X(n)] where X = NCS, NO(3) and Cl; m = 0 or 1, and n = 1 or 2. The complexes .have been characterised on the basis of analytical, spectroscopic, magnetic and conductance data. The anti-fungal activities of the ligand and its complexes have been investigated against a range of phytopathogenic fungi.     

Kinetic Aspects of Redox Reactions of Nickel(III) Complexes

The synthesis and characterisation of nickel(III) complexes are reviewed. Kinetic aspects of redox reactions including oxidation by Co(OH₂)³⁺₆ and Fe(phen)³⁺₃ are described, as are the reactions involving oxidation of non-metallic substrates. Reference is made to the evaluation of self-exchange rates for the Ni(III)L/Ni(II)L couples, especially for systems where both oxidant and reductant retain an octahedral geometry. Using the reversible reaction between Ni(9-aneN₃)³⁺₂ and Ni(10-aneN₃)³⁺₂ (9-ane = 1,3,7-triazanonane, 10-ane = 1,3,7-triazadecane), data are presented for evaluation of the self-exchange rate constant for the Ni(10-aneN₃)^3+/2+₂ couple [(7.5 ± 1) X 10³ M⁻¹s⁻¹]. This value is compared with that for similar systems where changes in bond lengths on oxidation have been determined by X-ray techniques.     

Development of Novel DNA Cleavage Systems Based on Copper Complexes. Synthesis and Characterisation of Cu(II) Complexes of Hydroxyflavones

Copper(II) complexes of several hydroxyflavones were prepared and characterised through their physico-chemical properties. The nuclease activity of three synthesised complexes is reported. These copper(II) complexes present more nuclease activity than the ligands and the copper(II) ion.     

琥珀酰化壳聚糖-铜(Ⅱ)-苯并咪唑衍生物配合物的合成、表征及抗菌活性

文章利用琥珀酸酐对壳聚糖进行改性,并合成了两个新的配合物:sucts-Cu(Ⅱ)-hpb(1)和sucts-Cu(Ⅱ)-tbz(2)[sucts=琥珀酰化壳聚糖,hpb=2-(2’-吡啶)-苯并咪唑,tbz=2-(4′-噻唑基)苯并咪唑]。应用红外光谱,紫外-可见光谱,原子吸收光谱对配合物进行了表征,采用试管倍比稀释法研究了这些配合物对苏云金杆菌、枯草芽孢杆菌、大肠杆菌和金黄色葡萄球菌的抑制作用。结果表明,两种配合物对四种细菌均有较强的抑菌活性,配合物1、2,最小抑菌浓度(MIC)分别为62.5～125μg.mL-1和125～250μg.mL-1,抗菌效果明显强于自由配体。     

Synthesis, Ligational and Biological Properties of Cobalt(II), Copper(II), Nickel(II) and Zinc(II) Complexes With Pyrazinedicarboxaimide Derived Furanyl, Thienyl and Pyrrolyl Compounds

Preparation, ligational and biological properties of some pyrazinedicarboxaimide derived furanyl, thienyl and pyrrolyl compounds with Co(ll), Cu(ll), Ni(ll) and Zn(ll) metals are described. Magnetic moments, electronic, infrared, nuclear magnetic resonance spectra and elemental analysis data indicate that co-ordination of the ligands with the metal ions take place through the pyrazine ring nitrogen, azomethine nitrogen and heteroatom of heterocyclic ring system. The compounds are all novel and are proposed to possess an octahedral geometry for Co(ll) and Ni(ll), and a distorted octahedral geometry for Cu(ll) and Zn(ll) complexes. The comparative biological properties of the title ligands and their metal chelates against different bacterial species are also described.     

Synthesis, Spectral and Antibacterial Studies of Copper(II) Tetraaza Macrocyclic Complexes

A novel family of tetraaza macrocyclic Cu(II) complexes [CuLX(2)] (where L = N(4) donor macrocyclic ligands) and (X = Cl(-), NO(3) (-)) have been synthesized and characterized by elemental analysis, magnetic moments, IR, EPR, mass, electronic spectra and thermal studies. The magnetic moments and electronic spectral studies suggest square planar geometry for [Cu(DBACDT)]Cl(2) and [Cu(DBACDT)](NO(3))(2) complexes and distorted octahedral geometry to the rest of the ten complexes. The biological activity of all these complexes against gram-positive and gram-negative bacteria was compared with the activity of existing commercial antibacterial compounds like Linezolid and Cefaclor. Six complexes out of twelve were found to be most potent against both gram-positive as well as gram-negative bacteria due to the presence of thio group in the coordinated ligands.     

Polymerization of Methyl Methacrylate with Nickel(II) and Palladium(II) Iminopyridyl Mononuclear Bimetallic Complexes

Methyl methacrylate polymerizations with a series of Pd(II) or Ni(II) bimetallic catalysts having general formula [(2-C₅H₄N)–C=N–(Z)–N=C–(2-C₅H₄N)] [MX₂]₂ {Z = (2,6-C₆H₂R₂)₂CH(4-C₆H₅); R = Me, iPr, MX₂ = PdCl₂, NiBr₂} in combination with methylaluminoxane showed that bimetallic Pd(II) catalysts are much more active than their bimetallic Ni(II) nickel and monometallic analogs to give syndiorich poly(methyl methacrylate) with moderate molecular weight.     

Hexa-coordinated Complexes of Nickel(II) bis(methylacetoacetate) with aromatic heterocyclic amines

Hexa-coordinated complexes of nickel(II) bis(methylacetoacetate) with pyridine, β-picoline and β-picoline have been prepared and characterised. Conductance measurements in methanol indicate non-electrolytic nature of the complexes. The complexes are all pale blue in color and are paramagnetic (μ_eff. = 3.0–3.1 B.M.). Electronic spectra and magnetic moment identify the complexes as octahedral ones. The d-d spectra of the complexes are discussed in the light of the structure of the complexes. The spectrophotometric data for the adducts have been used to calculate the values for the parameters, Δ, B′, β and λ.     

Synthesis, Characterisation and Antifungal Activities of Some New Copper(II) Complexes of Isomeric 3,5,7,7,10,12,14,14-Octamethyl-1,4,8,11-Tetraazacyclotetradecanes

Three isomeric Me(8)[14]anes, L(A), L(B) and L(C), undergo complexation with copper(II) salts to form a series of [CuLX(n)(H(2)O)(x)]X(y).(H(2)O)(z) complexes where L = L(A), L(B) and L(C); X = Cl, Br, NO(3); n, x, y and z may have values of 0, 1 or 2. The complexes have been characterised on the basis of analytical, spectroscopic, magnetic and conductance data. Further, the X-ray crystal structure of one complex, [CuL(B)(OH(2))(2)](NO(3))(2), has been determined. The antifungal activity of all three isomeric ligands and their complexes has been investigated against a range of phytopathogenic fungi.     

Antineoplastic and Cytotoxic Activities of Nickel(II) Complexes of Thiosemicarbazones

Nickel(II) complexes of thiosemicarbazons were observed to be potent cytotoxic agents in human and rodent tissue cultured tumor cells. Each compound demonstrated a slightly different profile in the various histological types of tumors. The nickel complex of Appip demonstrated the most potent in vivo activity in the Ehrlich ascites carcinoma. This agent selectively inhibited L1210 DNA and purine syntheses, and DNA polymerase alpha, PRPP-amido transferase, IMP-dehydrogenase, dihydrofolate reductase, TMP-kinase and thymidylate synthetase activities. L1210 DNA strand scission was evident and DNA viscosity was reduced after 24 hr incubation. The nickel complexes were not L1210 DNA topoisomerase II inhibitors.     

Solvent-Extraction Behavior of Cobalt(II), Nickel(II), Copper(II), and Palladium(II) with Tri-n-butylphosphate

Abstract

A systematic study of the extraction behavior of cobalt(II), nickel(II), copper(II), and palladium(II) with TBP from thiocyanate system in various ranges of acid concentrations has been performed. The thiocyanate medium leads to enhanced extractions in all these cases compared to those in the previously used chloride medium. For palladium, the chloride and nitrate systems have been critically examined. Sixty-two per cent extraction occurs from 4 M hydrochloric acid using 100% TBP in a single run and the extraction becomes quantitative (>99%) after four successive equilibrations. A simpler method has been proposed for rapid extraction of palladium(II) as the thiocyanate complex. Quantitative extraction occurs in the presence of 1.2% thiocyanate solution from 0.5 to 2 M hydrochloric acid (initial) up to pH 8.0. The extractable species of cobalt(II), nickel(II), copper(II), and palladium(II) from thiocyanate medium are probably similar and of the type [M(CNS)₄]^2? [K·TBP·3H₂O]₂ ⁺ (buffer solution) and [M(CNS)₄]^2? [H·TBP·3H₂O]⁺ ₂ (acid solution). A simple extraction scheme has been worked out for the separation of palladium(II) from iron(III), cobalt(II), nickel, manganese(II), copper(II), and platinum.     

光谱法研究邻菲罗啉锌与DNA的相互作用

在模拟人体生理条件下(pH 7.4),运用荧光光谱和紫外可见吸收光谱研究了邻菲罗啉锌(Zn(phen)2+3)与小牛胸腺DNA(ctDNA)之间的相互作用。研究结果显示,ctDNA对Zn(phen)2+3的荧光猝灭机制属于静态猝灭。根据修正的Stern-Vomer方程计算了不同温度下的结合常数,并结合Van′t Hoff方程计算出相应的热力学参数,焓变值(ΔH=-7.029kJ/mol)和熵变值(ΔS=50.631J/(mol·K)表明静电作用力是维持Zn(phen)2+3-ctDNA复合物稳定的主要作用力。此外离子强度实验和KI荧光猝灭实验也证实了Zn(phen)2+3与ctDNA间通过静电作用的方式结合,而不是沟槽作用和嵌插作用。     

Sonochemical Synthesis of Two New Nano-structured Cadmium(II) Supramolecular Complexes

Nano-particles of two new Cd(II) supramolecular complexes, [Cd(4,4-di-tert-bubipy)Cl₂(DMSO)] (1) and [CdI₂(4,4′-dmbpy)(DMSO)] (2) have been synthesized by sonochemical process and characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. The structure of compound 1 has been characterized by single crystal X-ray diffraction. The prepared nano-structure was characterized by scanning electron microscopy and X-ray powder diffraction. The nano-structures of supramolecular complexes have been synthesized with calcination of complexes at oleic acid as a surfactant at 190 ºC too. The size of the samples prepared by sonochemical method and calcination are about 30–40 and 40–50 nm respectively.     

Copper(II) Complexes of Pyridazine-Based Azo-azomethine Ligands: Synthesis, Characterization Thermal and Absorption Properties

New copper(II) complexes with blue–violet light wavelength absorption were synthesized using direct reaction of acyclic azo-azomethine pyridazine-based ligands with copper ion. The prepared complexes were characterized using elemental analysis, spectroscopic methods and thermal analyses. The absorption properties of the prepared complexes in the region 200–800 nm and also the influence on the difference of absorption maximum of complexes were investigated. The thermogravimetric results show that the framework of all complexes is stable up to 270–320 °C.     

Synthesis and Third-Order Nonlinear Optical Properties of Copper and Nickel Coordination Complexes of Azo Dyes

An azo dye, 2-(4,5-dicyano-1-H-imidazolyazo)-5-N, N-diethylaminophenol, and the corresponding divalent copper and nickel mononuclear coordination complexes were synthesized. The molecular third-order nonlinear optical characteristics of these azo transition metallic chelates were investigated in N,N′-dimethylformamide solution using a standard Z-scan technique with a 7-ns laser pulses at 1,064 nm. The results of n ₂ (the nonlinear refraction index) and γ (the hyperpolarizability) values of the two complexes indicated that metal chelating lead to considerable enhancement in third-order optical nonlinearities, which revealed that such coordination complexes exhibit strong nonlinear optical absorption effects and self-defocusing performance. These materials are promising candidates as large third-order nonlinear optical materials.     

Separation of Nickel(II) Amino Acid Complexes on Silica Gel

Abstract

Chromatography of 25 nickel(II) amino acid chelates on silica gel using phenol-water 75:25 (w/w) as solvent system was described. In general, it was found that adsorbability of complexes formed with terdentate ligands is greater than that of complexes formed with bidentate ligands. In other cases R_F values increased with the increasing number of carbon atoms present in the chelate molecule. Steric effects of side chains of amino acids, which influenced the degree of solvation of nickel ion, were also considered.