Rotaxane Type Complexation Behavior of Cyclodextrins with a Series of Donor–Acceptor Covarently Linked Compounds

The complexation behavior of a series of electron donor–accepter (D–A) covalently linked compounds with cyclodextrins (CyDs) has been reviewed. The structure of these complexes showed rotaxane type conformations, which were investigated by means of ¹ H NMR spectrometry. The complex formations induced a fixation of a conformation of guest D–A molecules, and D–A distances were enlarged. Thus, accurate photo-induced charge transfer behaviors can be discussed.     

Selective Pseudo-Rotaxane Type Complex Formation of Zinc(II) (t-butylatedtetraphenyl) porphyrin-Viologen Linked Compounds with tri-O-methyl-β-Cyclodextrin

Inclusion complexation behavior of 2,3,6−tri-O-methyl-β-cyclodextrin (TM-β-CD) with zinc(II) 5,10,15-tri-(4-t-butyl-phenyl)-20-(4-(n-alkyloxy)phenylporphyrin covalently linked with violgen by a polymethylene chain (Zn-t- bu-PC _n V²⁺; n=4, 6, 8, 10 and 12) was investigated by means of ¹H NMR, UV/Vis absorption spectroscopies in acetonitrile-water (1:1, v/v). The ¹H NMR spectra indicated that Zn-t-bu-PC _n V²⁺ presumably existed as a mixture of a dimer and a monomer in high concentration (>1×10⁻³ mol dm⁻³), and the dimer was degraded by the complex formation with TM-β-CD. The ¹H NMR spectra of these compounds as a function of [TM-β-CD] showed the selective formation of 1:1 (=Zn-t-bu-PC _n V²⁺: TM-β-CD) pseudo-rotaxane type complexes. The chemical modification by t-butyl groups on porphyrin showed a good protective effect on inclusion of benzene groups into the TM-β-CD cavity. These rotaxane formation constants (K) were determined by titration studies using UV/Vis absorption spectroscopy. These complex formation constants were somewhat affected by the spacer methylene chain between the porphyrin and viologen. The value of K for Zn-t-bu-PC₄V²⁺·TM-β-CD is 1.0×10³ M⁻¹ which is the smallest whereas those for Zn-t-bu-PC _n V²⁺·TM-β-CD (n=8, 10, 12) were similar (1.0×10⁴ M⁻¹).     

Thermodynamic Complexation of Dopamine with Zinc(II) in Media with Different Dielectric Constants

The complexation of zinc(II) with dopamine has been investigated by spectrophotometric measurements in mixed solvent system at an ionic strength of 0.2 mol•dm－3 sodium chloride, employed at at (15±0.1), (25±0.1), (35±0.1) ℃ at inin a pH range of ca. 6 to ca. 7 with a high ratio of ligand to metal. The effect of solvent systems on protonation and complexation are was was discussed. Linear relationships are werewere observed by plotting lg K versus 1/D, where K and D show stability and dielectric constants, respectively.     

Complexation of Baicalin with Ferrous (II) and Its Characterization

The complexation of baicalin with ferrous (II) and its characterization are reported. A orthogonal test was used to optimize the conditions of the complexation of baicalin and ferrous (II). The composition and structure of baicalin-ferrous (II) complex were characterized by elementary analysis, TG-DTA methods, and IR- and UV-spectral analysis. Coordination bonding is dependent on the nature of the baicalin and ferrous (II) ion, their ratio, the pH of the solution, etc. The strongest complex forms between baicalin and ferrous (II) (2:1 ratio).__________Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 129–131, March–April, 2005.     

Blue Luminescent Zinc(II)-and Cadmium(II)-1,4-phenylenediacetate Complexes

1 INTRODUCTION The crystal engineering and design of solid-state coordination polymers have become a very attrac- tive field in recent years[1～4]. Many interesting fra- meworks with intriguing potential applications have been obtained through the self-assembly of selected metal centers and carboxylate ligands[5, 6]. Compared with aromatic carboxylate ligands such as terephtha- lic acid[7, 8], benzene tricarboxylic acid[9, 10], benzene tetracarboxylic acid[11, 12] and so on, those ligands …     

Multinuclear Magnetic Resonance Study of Zinc(II) and Cadmium(II) Complexing with Isothiocyanate

A study of zinc(II) and cadmium(II) complexes with isothiocyanate ion has been completed, using a low-temperature, multinuclear magnetic resonance technique that permits the observation of separate resonance signals for bound and free ligand, and Cd(II) metal ion. The Zn²⁺–NCS^– complexes were studied by ¹H, ¹³C, and ¹⁵N NMR spectroscopy. In the ¹H spectra, the intensity of the coordinated water signal, corresponding to a Zn(II) hydration number of six in the absence of NCS^–, decreases dramatically as this anion is added, indicating the complexing process involves more than a simple 1:1 ligand replacement. The ¹³C and ¹⁵N NMR spectra reveal signals for four species, most reasonably assigned to a series of tetrahedrally coordinated Zn²⁺–NCS^– complexes. In the Cd²⁺–NCS^– solution spectra, the ¹³C and ¹⁵N signals for four complexes also are observed and they are three line patterns, corresponding to a doublet from ¹¹³Cd J-coupling, and a dominant central peak, resulting from bonding to magnetically inactive Cd isotopes. The ¹¹³Cd spectra, showing signals for four complexes, correlate well in all respects with the ¹³C and ¹⁵N results, including coupling in specific cases. The spectral results for both metal ions reflect binding at the nitrogen atom of NCS^–, with the complexes changing from an octahedral to a tetrahedral configuration when doing so. Confirming evidence for these conclusions also was provided by several infrared measurements of these metal–ion systems.     

Urothermal Syntheses of two New Luminescent Zinc(II) Compounds via Dual-ligand Strategy

Urothermal reaction of Zn(NO₃)₂ · 6H₂O, Htrz and NH₂H₂pdc or H₂pdc affords two new compounds, namely [Zn₂(NH₂bdc)(trz)₂]_n · 2n(e-urea) ( 1 ) and [Zn₄(bdc)₂(trz)₄(H₂O)(e-urea)]_n · n(e-urea) ( 2 ) (Htrz = 1,2,4-triazole, NH₂H₂bdc = 2-aminoterephthalic acid, H₂bdc = terephthalic acid, e-urea = 1,3-ethyleneurea). X-ray structural analyses revealed that both compounds 1 and 2 feature e-urea-templated 3D pillar-layer framework with 2D Zn^II-triazole layer and 6-connected pcu topological network. These two compounds not only have high thermal stabilities but also show intense luminescence at room temperature.     

Bis(pyrazol-1-yl)propane as a bulky Ligand: X-ray Crystal Structure Determination of its Adduct with Zinc(II) Chloride

The steric misfit between a geminal bis(pyrazol-1-yl)propane ligand and tetrahedral coordination leads to distortion of the latter in the title compound: N? Zn? N is 89.5(1)°, Cl? Zn? Cl 116.78(5)°. Comparison of the Zn? N (2.058(3), 2.046(3) Å) and Zn? Cl (2.209(1), 2.229(1) Å) distances with those of related compounds evidences the steric bulkiness of the title ligand.     

Zinc(II) and Cadmium(II) Metal Complexes with Bis(tetrazole) Ligands: Synthesis and Crystal Structures

Two new metal complexes [Zn( L¹ )]_n ( 1 ) and [Cd₃( L² )₂Cl₂(H2O)6]_n ( 2 ) (H₂ L¹ = 1,5‐bis(tetrazol‐5‐yl)‐3‐oxapentane, H₂ L² = bis(tetrazol‐5‐yl)methane) have been synthesized and characterized by elemental analysis, IR spectroscopy and single‐crystal X‐ray diffraction analysis. Complex 1 was a 2‐D sheet constructed by L¹ and Zn(II) center, further assembled to form a three‐dimensional (3‐D) supramolecular networks through weak hydrogen‐bonding interactions. In the complex 2 , there were two unequivalent Cd(II) centers, and some of ligands L² adopted chelate coordination mode, and others adopted bridge coordination mode linking the Cd1 center and simultaneously bridging the Cd2 center, the Cl^‐ anions adopted μ₂ bridging mode, ligands L² and the Cl^‐ anions linked the Cd(II) centers to form a 3‐D supramolecular networks.     

Complexes of Co(II) and Zn(II) with N-(Thio)phosphorylthioureas AdNHC(S)NHP(O)(OiPr)2 and MeNHC(S)NHP(S)(OiPr)2

The reaction of the potassium salt of the N-(thio)phosphorylated thioureas AdNHC(S)NHP(O)(OiPr)₂ (HL^I , Ad = Adamantyl) and MeNHC(S)NHP(S)(OiPr)₂ (HL^II ) with Co(II) and Zn(II) in aqueous EtOH leads to [ML^I,II ₂] chelate complexes. They were investigated by UV-vis, ¹H and ³¹P NMR spectroscopy, and microanalysis. The molecular structures of [ML^I ₂] were elucidated by single crystal X-ray diffraction analysis. The metal centers in both complexes are found to be in a distorted-tetrahedral O₂S₂ environment formed by the C=S sulfur atoms and the P=O oxygen atoms of two deprotonated L^I ligands. The photoluminescence properties of [ZnL^II ₂] are also reported.     

Study of Inclusion Complexes of Cyclodextrins with Orange II

Inclusion reactions of - and -CD with Orange IIwere measured by means of a stopped-flow method and UV-spectra. The forward rate constants (k₊), backward rateconstants (k_-) and the equilibrium constants (K) for the inclusion reactions were determined. Theinclusion processes of CD with Orange II follow a one-step reaction mechanism. The value of the forward rate constantat neutral and alkaline conditions for Orange II binding to -CD cavity was large. This suggests that thenaphthalene side is partially included in the final complex form. In the case of -CD, only marginal differenceis shown.It is probable that inclusion covers the whole naphthalene group and part of the azo group as well,resulting ina small effect from the pH variation. The results show that the equilibrium constant at pH 7 for the binding ofOrange II to -CD is the largest because the included part of Orange II matches the cavity of -CD well.     

1，3，5－三咪唑基苯－醋酸锌配合物的合成、结构和离子交换性质研究

报道了一个由新型三角架配体1,3,5-三咪唑基苯（L）与Zn(CH_3COO)_2· 2h_2O组装得到的配合物：[Zn(L)_2(H_2O)_2]-(CH_3COO)_2·2H_2O (1)，用X射线 单晶衍射法测定了配合物的晶体结构，该晶体属单斜晶系，空间群P2_1/n，晶胞参 数a = 0.8339(1) nm, b = 1.2209(2) nm, c = 1.7565(3) nm, β = 94.880(3)° ，D_c = 1.383 g/cm~3, μ = 1.505 mm~(-1), F(000) = 1560, R_1 = 0.0429, wR_2 = 0.0713。配合物1具有二维层状结构，醋酸根阴离子位于层与层之间的孔 道中，并且可以被硝酸根离子交换。     

Acid Dissociation Behaviour and Complexation with Nickel(II), Copper(II) and Zinc(II) for Two Conformational Isomers of Dicyclohexylcyclam

Abstract

Acid dissociation constants for two conformational isomers of dicyclohexylcyclam, cis-anti-cis, (P) and cis-syn-cis, (N) have been determined at 25, 35 and 40°C, and thermodynamic data are estimated. It was found that (N) shows very different behaviour from (P). Stability constants of (P) and (N) toward Ni(II), Cu(II) and Zn(II) have been determined by pH-titration at 25°C by using a ligand exchange reaction. It is found that the (P) complex is more stable for Ni(II) and the (N) complex is more stable for Cu(II). Contributions of the cyclohexyl group to the macrocyclic effect (ME) have been also estimated by considering basicity corrections. It is found that substitution of the cyclohexyl group in cyclam increases ME only for the Ni(II) complex of (P).     

环糊精与大分子组装(准)聚轮烷

（准）聚轮烷是一种通过非价键相互作用组合得到的超分子结构,其中环糊精与大分子间的组装以其选择性、可调控性和生物相容性等优势引起广泛关注。本文综述了近年来环糊精与大分子组装（准）聚轮烷的研究进展,着重介绍了其在理论和应用方面的研究成果。     

Thermal Behaviour of New Zinc(II) Bromobutyrate Complex Compounds

New zinc bromobutyrate complexes of general formula ZnX₂·1−L·nH₂O (X=CH₂Br(CH₂)₂COO⁻; CH₃CH₂CHBrCOO⁻) containing one or two molecules of caffeine, nicotin-amide and phenazone as ligands (L) were prepared. The compounds were characterized by MS-, IR- spectroscopy, chemical and thermal analysis. The thermal decomposition of hydrated compounds starts by the release of water molecules. In anhydrous compounds the loss of organic ligands takes place followed by the decomposition of the bromobutyrate anion at higher temperatures. Zinc bromide was found among the final products of thermal decomposition. Water, carbon monoxide, propylaldehyde, vinylaldehyde and formaldehyde were detected in the gaseous products of the thermally decomposed samples on heating up to 700°C. This revised version was published online in August 2006 with corrections to the Cover Date.     

Syntheses and Crystal Structures of Zinc(II) and Nickel(II) Complexes Involving Reduced Nitroxide Radicals

1 INTRODUCTION The synthesis of new molecular magnetic mate- rials that combine transition metal ions and pure organic radicals as ligating sites has attracted much more attention in the last few years[1~4]. Nitronyl ni- troxide radicals, independently or in combination with metal ions, have been one of the most studied systems in molecular magnetism for understanding the radical-radical or metal-radical interactions as well as for synthesizing organic ferromagnets and metal-radical magne…     

Synthesis, Crystal Structure and Kinetic Mechanism of Thermal Decomposition of a Zinc(II) Complex with N-Salicylidene-p-toluidine

1 INTRODUCTION Over the past decades, considerable attention has been devoted to the synthesis, characterization and property studies of Schiff bases and their com- plexes because of their potential and developed appli- cations in the fields of conducting and magnetic ma- terials, dyes, non-linear optics, catalysis, analytical chemistry, biochemical research, agriculture and so on[1～7]. A large number of reports are available in the chemistry and biologic activities of transition metal co…     

铜(II)-铬(VI)复合均匀胶体粒子的制备

报导在尿素存在下通过均相沉淀法由硝酸铜和重铬酸铵制备复合均匀胶体粒子的结果．研究了一些实验参数对其组成、形态和粒子大小的影响．确定了胶体粒子的制备条件．结果观测到，由硝酸铜和重铬酸铵溶液形成了球形的多刺的粒子，它的组成为水含铅酸铜．     

Zinc(II) (o-hydroxybenzaldoximates) Complexes with Mono- and Bidentate Ligands

New complexes:Zn(Hsalox)(ox), Zn(Hsalox)(NHPh), Zn(Hsalox)(Hsal) and Zn(Hsalox)₂(1,2-diMeim) have been synthesised as a result of a reaction of Zn(salox) and Zn(Hsalox)₂ (where: salox ^2–=OC₆H₄CHNO^2–, Hsalox ^–=OC₆H₄CHNOH^–) with 8-hydroxyquinoline (Hox), o-aminophenol (NH₂Ph), o-hydroxybenzoic acid (H₂Sal) and 1,2-dimethylimidazole (1,2-diMeim). Chemical, X-ray and thermal analyses of the complexes and their sinters have been carried out. Thermal decomposition pathways have been postulated for the complexes. The mixtures about not definite composition have been obtained as a result of a reaction of zinc(o-hydroxybenzaldoximates) with imidazole(Him) and 4-methylimidazole (4-MeHim). This revised version was published online in August 2006 with corrections to the Cover Date.     

Combinations of Cyclodextrins with Synthetic and Natural Compounds

Host–guest compounds formed by cyclodextrins with synthetic and natural compounds are reviewed with regard to their properties, characterisation (using experimental and computational methods) and applications.