Thermal Analysis in Structural Characterization of Hydrazone Ligands and Their Complexes

Results of our research on synthesis and characterization of complexes with acylhydrazone derivatives are described in this review paper. Structural characterization of newly synthesized complexes by thermal analysis (TG, DTA, DSC) is particularly emphasized in this paper. Thermal analysis enabled us to study not only structural changes of substances during thermal treatment, but also the mode of coordination and degree of deprotonation of acylhydrazones, as well as geometry of the coordination sphere of complexes, the structure of which had not been determined by X-ray analysis. Topics in this paper are as follows: complexes of dioxomolybdenum(VI) with tridentate hydrazones, usnic acid derivatives and their Cu(II) complexes, as well as transition metal complexes with 2,6-diacetylpyridine bis(hydrazones). This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis,Characterization and Antimicrobial Activity of a New Aromatic Sulfonyl Hydrazone Derivative and Its Transition Metal Complexes

In this study, benzenesulfonicacid‐1‐methylhydrazide (bsmh) derivatives such as 2‐hydroxy‐1‐naphtaldehydebenzenesulfonylhydrazone (Hnafbsmh) and its Ni(II), Pd(II), Pt(II), Cu(II), Co(II) complexes were synthesized. The structures of these complexes were investigated using elemental analyses (FT‐IR, LC‐MS, UV‐VIS), magnetic susceptibility and conductivity measurement techniques. The complexes were found to have general compositions [ML₂]. All the synthesized complexes were evaluated in vitro as antimicrobial agents against representative strains of six gram‐positive and four gram‐negative bacteria and as an antifungal agent by disc diffusion methods. All the bacteria and fungi studied were screened against some commercial antibiotics to compare them with our chemical's zone diameters.     

Synthesis,Spectroscopic Characterization and Properties of New Metal Complexes

A new series of the polydentate Schiff base Cu^II, Co^II, Ni^II, Pd^II and Zn^II complexes derived from ethylenediamine (eda), diethylenetriamine (dea) and tris(2-aminoethyl)amine (taa) have been prepared by template condensation in MeOH solution, and characterized by i.r., electronic spectral data, elemental analyses, conductivity and magnetic measurements. The ¹H- and ¹³C-n.m.r. and mass spectral data of the Ni^II, Pd^II and Zn^II complexes have been recorded. In all complexes, some of the chloride ions coordinate to the metal ions. From conductivity measurements, it is shown that the complexes are electrolytes. The Ni^II, Pd^II and Zn^II complexes have diamagnetic character. In this study, the Schiff base Cu^II and Co^II complexes have sub-normal magnetic moments commensurate with their binuclear or tetranuclear nature. Some show antimicrobial activity against bacteria and yeast.     

水杨醛水杨酰腙及其稀土配合物的合成、波谱研究及生物活性

合成了水杨醛水杨酰腙(C_(14)H_(12)N_2O_3,简写为H3L)及其与稀土的13种未 见文献报道的配合物.经容量分析、元素分析及摩尔电导率测定，确定了配合物的 组成为K[RE(HL)_2]·nH_2O(RE=La,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Er,Tm,Yb,Lu,Y,HL=水 杨醛水杨酰腙的负二价离子),通过IR,~H NMR,UV讨论了其成健情况;由FS探讨了配 合物的荧光发射波长随稀土的原子序数、离子势所呈现的规律性，生物活性试验表 明，该配体及其配合物对辣椒疫霉菌、棉花枯萎病菌和烟草赤是菌等均有不同程度 的抑制作用。     

含二茂铁基Schiff碱及其过渡金属配合物的合成与表征

合成了两个新型含有二茂铁基的schiff碱配体及其8种过渡金属配合物,并通过^1HNMR,IR,元素分析,热分析和摩尔电导对其结构进行表征,提出了配合物的可能结构。     

钒酰腙配合物的合成、结构及生物活性

以酰腙为配体钒的单核、双核配合物因其结构丰富、生物活性多样而引起广泛关注。目前该领域新配合物的合成、表征和生物活性的研究甚为活跃。本文回顾了近年来钒酰腙配合物的研究状况,主要从以下三个方面进行综述：(1)钒酰腙配合物的合成方法;(2)此类配合物的配位模式;(3)一些单、双核钒酰腙配合物抗变形虫,抗肿瘤,类胰岛素,抑制Na⁺, K⁺-ATP酶,与DNA作用的生物活性。文中着重阐述了钒酰腙化合物的结构和生物活性之间的关系。此外,还提出了钒酰腙配合物研究领域的不足之处并对其今后发展方向进行了展望。     

Synthesis and Characterization of Lanthanide Metal Ion Complexes of New Polydentate Hydrazone Schiff Base Ligand

The new homodinuclear complexes of the general formula [Ln₂L₃(NO₃)₃] (where HL is newly synthesized 2-((2-(benzoxazol-2-yl)-2-methylhydrazono)methyl)phenol and Ln = Sm³⁺ (1), Eu³⁺ (2), Tb³⁺ (3a, 3b), Dy³⁺ (4), Ho³⁺ (5), Er³⁺ (6), Tm³⁺ (7), Yb³⁺ (8)), have been synthesized from the lanthanide(III) nitrates with the polydentate hydrazone Schiff base ligand. The flexibility of this unsymmetrical Schiff base ligand containing N₂O binding moiety, attractive for lanthanide metal ions, allowed for a self-assembly of these complexes. The compounds were characterized by spectroscopic data (ESI-MS, IR, UV/Vis, luminescence) and by the X-ray structure determination of the single crystals, all of which appeared to be different solvents. The analytical data suggested 2:3 metal:ligand stoichiometry in these complexes, and this was further confirmed by the structural results. The metal cations are nine-coordinated, by nitrogen and oxygen donor atoms. The complexes are two-centered, with three oxygen atoms in bridging positions. There are two types of structures, differing by the sources of terminal (non-bridging) coordination centers (group A: two ligands, one nitro anion/one ligand, two nitro anions, group B: three ligands, three anions).     

Macrocyclic Metal Complexes Bearing Rigid Polyaromatic Ligands: Synthesis and Catalytic Activity

We synthesised palladium and platinum complexes possessing cyclic and acyclic pincer‐type polyaromatic ligands and investigated their structural effect on the catalysis. The pincer‐type bis(6‐arylpyridin‐2‐yl)benzene skeleton was constructed via Kröhnke pyridine synthesis under transition metal‐free conditions on gram‐scale quantity. Ligand structure significantly influenced catalytic activity toward the platinum‐catalysed hydrosilylation of diphenyl acetylenes, despite the ligand‐independence of the conformations and electronic properties of these complexes.     

Transition Metal Complexes of Propranolol Dithiocarbamate: Synthesis, Characterization, Analytical Properties and Biological Activity

Propranolol dithiocarbamate (PDTC) and its complexes with Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) have been synthesized and characterized by elemental analyses, FT-IR, electronic spectra, atomic absorption spectra, molar conductance, mass and ¹H-n.m.r. spectral data. Information on the stoichiometry of the complexes was obtained from the continuous variation method (Job’s method). The thermal decomposition behaviour of PDTC metal complexes was investigated in a nitrogen atmosphere using TG and DTA techniques. The antimicrobial activity studies of the metal complexes have been recorded against the Bacillus megaterium, Bacillus brevis, Yersinia enterocolitica, Micrococcus luteus, Pseudomonas aeruginosa, Enterococcus faecalis, Kluyveromyces marxianus, Candida tropicalis, Candida albicans and Kluvyeromyces fragilis.     

α-酮戊二酸-2,4-二硝基苯腙稀土配合物的合成与表征

驰豫效率;α-酮戊二酸-2;4-二硝基苯腙稀土配合物的合成与表征     

具有生物活性的芳香族腙类衍生物的合成与表征

在冰盐浴条件下, 芳香族重氮盐与活泼亚甲基化合物反应, 合成了六种新芳香族腙类衍生物. 产物经IR, ¹H NMR, ¹³C NMR, 元素分析表征, 其中3b和3e经X射线单晶衍射测定, 确认了其化学结构.     

非天然氨基酸水杨醛席夫碱铜配合物的合成与表征

合成了N-亚水杨基β-丙氨酸铜(1)和N-亚水杨基牛磺酸铜(2)两种新配合物,用元素分析、摩尔电导、红外光谱、热重差分析、X-射线粉末衍射对所合成的配合物进行了表征,并对X-射线粉末衍射数据进行了指标化.两种配合物的组成分别为Cu(sal-β-ala)*H2O(1),Cu(sal-tau)*2H2O(2),X-射线粉末衍射数据指标化结果表明,两种配合物均属于正交晶系,晶胞参数分别是1a=1.4981nm,b=1.8246nm,c=2.1985nm;2a=0.9454,b=1.7092nm,c=2.2254.     

Synthesis and Spectroscopic Characterization of Transition Metal Complexes of Maleionitriledithiolate and 5-Nitro-Phenanthroline

The dithiolenes and diimines and their metal complexes are an important research field in the organic and coordination chemistry^[1-3]. Transition metal complexes of a dithiolene and a diimine have excellent electronic functions due to the intramolecular charge transfer from a ligand to other ligand (LL'CT)^[3], in which are interested authors^[4,5]. Recently we have been studied in detail the synthesis and properties of the title complexes M(mnt)(5-NO₂-phen), M=Mn^Ⅱ, Fe^Ⅱ, Co^Ⅱ, Ni^Ⅱ, Cu^Ⅱ, Zn^Ⅱ. The structure and properties of the M(mnt)(5-NO₂-phen) were characterized by the elemental analysis, TDA-TG, MASS, IR, UV-Vis, fluorescence and EPR spectra,molar conductivity and magnetic susceptibility. In the present abstract we report only the synthesis and spectroscopic characterization of these complexes.     

Metal Complexes Bearing Terminal Borylene Ligands

More and more metal complexes with terminal borylene ligands will be synthesized. Although these ligands in metal complexes must be stabilized either by integration of the boron atom into a polyhedral skeleton ( 1 ) or by B–N π interactions with a bulky amino group ( 2 ), the route to new complexes with terminal RB ligands (R=alkyl, aryl) is clearly indicated.     

Synthesis and Spectroscopic Characterization of Dinuclear Calcium Complexes with Oxa‐Aza Macrocyclic Ligands

The syntheses of dinuclear calcium perchlorate and/or nitrate complexes by template and direct methods, employing macrocyclic ligands with 18, 20, 22, and 26 membered rings are reported. The presence of pendant arms provide with coordinative NxOy donor atoms in the smaller macrocycles, the high number of donor atoms between 7 and 10, and the dinuclear composition obtained in all the systems examined, point out that in the formed solid complexes both Ca²⁺ ions could be located inside of the macrocycle cavities. Transmetallation reaction of a lanthanide(III) complex, [L⁵Sm](ClO₄)₃·9H₂O, with Ca(ClO₄)₂·xH₂O leads the formation of the new dinuclear orange [L⁵Ca₂](ClO₄)₄·3H₂O complex, manifesting the versatility of this macrocyclic cavity. All complexes have been characterized by microanalysis, IR, UV‐vis, ¹H NMR spectroscopy, FAB mass spectrometry, FAAS spectroscopy, and conductivity measurements.     

Review: Metal Complexes as Ligands

Ligand properties of coordination and organometallic compounds are examined on the basis of acid-base interactions of metal-containing bases and Lewis acids. Such interactions lead to homo- or heteronuclear di- and polynuclear complexes. Special attention is given to coordinatively-unsaturated molecules of classic Werner complexes, o -hydroxyazomethine chelates, metal carbonyls and their derivatives, ferrocenes with donor fragments, and coordinated heteroaromatic compounds.     

Synthesis of Novel Tritopic Hydrazone Ligands: Spectroscopy,Biological Activity,DFT, and Molecular Docking Studies

Polytopic organic ligands with hydrazone moiety are at the forefront of new drug research among many others due to their unique and versatile functionality and ease of strategic ligand design. Quantum chemical calculations of these polyfunctional ligands can be carried out in silico to determine the thermodynamic parameters. In this study two new tritopic dihydrazide ligands, N’2, N’6-bis[(1E)-1-(thiophen-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L1) and N’2, N’6-bis[(1E)-1-(1H-pyrrol-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L2) were successfully prepared by the condensation reaction of pyridine-2,6-dicarboxylic hydrazide with 2-acetylthiophene and 2-acetylpyrrole. The FT-IR, ¹H, and ¹³C NMR, as well as mass spectra of both L1 and L2, were recorded and analyzed. Quantum chemical calculations were performed at the DFT/B3LYP/cc-pvdz/6-311G+(d,p) level of theory to study the molecular geometry, vibrational frequencies, and thermodynamic properties including changes of ∆H, ∆S, and ∆G for both the ligands. The optimized vibrational frequency and (¹H and ¹³C) NMR obtained by B3LYP/cc-pvdz/6-311G+(d,p) showed good agreement with experimental FT-IR and NMR data. Frontier molecular orbital (FMO) calculations were also conducted to find the HOMO, LUMO, and HOMO–LUMO gaps of the two synthesized compounds. To investigate the biological activities of the ligands, L1 and L2 were tested using in vitro bioassays against some Gram-negative and Gram-positive bacteria and fungus strains. In addition, molecular docking was used to study the molecular behavior of L1 and L2 against tyrosinase from Bacillus megaterium. The outcomes revealed that both L1 and L2 can suppress microbial growth of bacteria and fungi with variable potency. The antibacterial activity results demonstrated the compound L2 to be potentially effective against Bacillus megaterium with inhibition zones of 12 mm while the molecular docking study showed the binding energies for L1 and L2 to be −7.7 and −8.8 kcal mol⁻¹, respectively, with tyrosinase from Bacillus megaterium.     

Synthesis,Characterization, and Properties of Tetraphenylethylene-Based Tetrakis-NHC Ligands and Their Metal Complexes

The development of highly emissive dinuclear Ag^I or Au^I complexes [M₂L](PF₆)₂ (L= 2 a , 2 b ; M=Ag, Au) derived from tetraphenylethylene (TPE)-based tetrabenzimidazolin-2-ylidene ligands is reported. The new complexes exhibit a remarkable fluorescence enhancement compared to their parent benzimidazolium salts. The quantum yield (Φ_F) value for salt H₄- 2 a (PF₆)₄ in dilute solution (c=10⁻⁵ m ) was found to be less than 1 %, whereas its metal complexes show Φ_F values up to 55 % at similar solution concentration. This observation can be attributed to the rigidification of the TPE skeleton upon metalation resulting in a restriction of the intramolecular rotation of the phenyl groups. Functionalization of the complexes [M₂ 2 b ](PF₆)₂ (M=Ag, Au) with terminal coumarin groups and subsequent photoirradiation yielded the complexes [M₂ 3 b ](PF₆)₂ (M=Ag, Au) bearing a new type of ligand with an unaffected TPE moiety.     

水杨醛缩氨基硫脲稀土有机配合物的合成及表征

由水杨醛缩氨基硫脲与三茂稀土Cp3Ln(Ln=La，Tb，Dy，Ho，Er，Yb)在THF中反应合成了6种新型配合物,经元素分析、IR，MR，XPS等表征表明它们为同时含Ln-0，Ln-N和Ln-S键的二聚体[CpLn(μ-O)C3H7N3S]2。