Syntheses and crystal structures of four silver(I) complexes based on 2-(4-pyridyl)benzimidazole

Four new silver(I) complexes constructed with 2-(4-pyridyl)benzimidazole, namely, [Ag(PyBIm) · H₂O] · NO₃ (1), [Ag(PyBIm) · H₂O] · ClO₄ (2), [Ag₂(PyBIm)₂] · (SiF₆) · 2H₂O (3) and [Ag(PyBIm) · (HBDC)] (4) (PyBIm = 2-(4-pyridyl)benzimidazole, BDC = 1,3-benzenedicarboxylate) have been synthesized and characterized by X-ray crystallography. All the silver(I) atoms in complexes 1–4 are bridged by the different PyBIm ligands via N_Py and N_BIm into one-dimensional “zigzag” chains. The anions do not coordinate to the silver(I) atoms and only act as counter ions in complexes 1–3. Due to the anions, different hydrogen bonding systems are found in those three compounds, resulting in the different crystal packing. Through hydrogen bonding interactions, the structures of complexes 1–3 display a double layer, a three-dimensional framework and a novel double chain, respectively. In complex 4, the HBDC⁻ anions act not only as a counter ion but also as bridging ligands, which lead the “zigzag” [Ag₂(PyBIm)₂]_∞ chain into a two-dimensional undulating sheet. The sheets are connected through hydrogen-bonding as well as π–π interactions into a three-dimensional framework. The thermal stabilities of the four complexes and anion exchange properties of complexes 2 and 3 were also studied.     

Self assembly of two novel three-dimensional supramolecular networks with blue photoluminescence

Two novel photoluminescent coordination polymers of the formula [Cd(Haip)₂(H₂O)₂] · 2H₂O (1) and [Zn(aip)(atz)] · 3H₂O (2) (H₂aip = 5-aminoisophthalic acid; atz = 3-amino-1,2,4-triazole) have been synthesized through the self-assembly of metal(II) ions with H₂aip and N-containing ligands [2-amino-5-mercapto-1,3,4-thiadiazole for 1 and 3-amino-1,2,4-triazole for 2, respectively] in the presence of NaOH. These complexes were characterized by FT-IR spectroscopy, thermogravimetric analysis (TG), elemental analysis and X-ray analysis. X-ray crystallographic studies of the complexes reveal that 1 is a first example where only one carboxylate group of the H₂aip ligand participates in coordination with the metal(II) ion and it exhibits a two-dimensional framework which further assembles into a three-dimensional supramolecular network via interlayer π–π stacking interactions and strong hydrogen bonds, while 2 exhibits a two-dimensional porous architecture. The extensively strong hydrogen bonds and interlayer π–π stacking interactions in 2 lead to the formation of a three-dimensional supramolecular network. Photoluminescence properties of the compounds 1 and 2 have been examined in the solid state at room temperature. These compounds have been found to exhibit blue photoluminescence and may be good candidates for photoactive materials.     

Synthesis and Photophysical and Electrochemical Study of Tyrosine Covalently Linked to High‐Valent Copper(III) and Manganese(IV) Complexes

As bio‐inspired chemical model of the oxygen‐evolving complex (OEC) in photosystem II, a new tyrosine‐modified corrole ligand 3 and its high‐valent copper and manganese complexes 3a and 3b were synthesized and characterized. The copper complexes 1a and 2a of corrole 1 and 2 were also prepared for comparison. The emission property indicates that the emission of ligands 2 and 3 is located at 670 nm, but no emission is observed for their metal complexes due to its suppression by the metal center. The electrochemical study shows that 3a might dimerize at the first two reversible oxidations, a behavior which was not observed in the case of 1a and 2a . The corrolato manganese(IV) complex 3b shows one reversible reduction and one quasireversible oxidation at ?0.17 and 0.77 V vs. Ag/Ag⁺, respectively.     

硒功能化杯芳烃载体银离子选择性膜电极的研究

合成6个硒功能化杯芳烃为载体,采用双层夹心膜电位法直接测定了溶剂聚合物膜中载体与金属离子生成的络合物生成常数。制备并考察了以硒功能化杯芳烃为载体的银离子选择性电极的性能,发现以载体6为银离子选择性电子的载体,制成的膜电极,用作Ag^ 电位滴定Cl^-的指示电极,效果最佳。     

Electrochemical Sensor for Sensitive Determination of Ga(III) Ion Based on β‐Cyclodextrin Incorporated Multi‐walled Carbon Nanotubes and Imprinted Sol‐gel Composite Film

A novel sensor for detection of trace gallium ion [Ga(III)] was created by stepwise modification of a gold electrode with β‐cyclodextrin (β‐CD)/multi‐walled carbon nanotubes (MWCNTs) and an ion imprinted polymer (IIP). The sensor surface morphology was characterized by scanning electron microscopy. The electrochemical performance of the imprinted sensor was investigated by cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The sensor displayed excellent selectivity towards the target Ga(III) ion. Meanwhile, the introduced MWCNTs displayed noticeable catalytic activity, and β‐CD demonstrated significant enrichment capacity. A linear calibration curve was obtained covering the concentration range from 5.0×10^?8 to 1.0×10^?4 mol·L^?1, with a detection limit of 7.6×10^?9 mol·L^?1. The proposed sensor was successfully applied to detect Ga(III) in real urine samples.     

Synthesis,Characterization, Antibacterial and Antifungal Activity of Yttrium(III) Complexes Including 1,10‐Phenanthroline

Two rare metal coordination complexes of yttrium(III) including 1,10‐phenanthroline, Y(phen)₂(NO₃)₃ and (phenH)₂[Y₂(pydc)₃(NO₃)₂·6H₂O] (phen=1,10‐phenanthroline, pydc=2,6‐pyridinedicarboxylate), and a proton transfer compound (phenH⁺)₂(pydc^2?) were synthesized and characterized by elemental analysis, molar conductance, infrared spectra (IR), nuclear magnetic resonance (NMR) and thermal analysis. The proposed structures of yttrium complexes were exhibited. The in vitro biological activities of the newly synthesized complexes have also been investigated against Bacillus coli, Staphylococcus aureus and Candida albicans. The results showed that yttrium(III) complexes including 1,10‐phenanthroline exhibited better antibacterial/antifungal activity than their ligands and corresponding compounds.     

Syntheses and Structures of Three Copper Coordination Polymers Based on Bis(triazol‐1‐ylmethyl)benzene

Three copper(II) coordination polymers [Cu(mbtz)₂(NCS)₂]_n ( 1 ), [Cu(mbtz)₂Cl₂]_n ( 2 ) and [Cu(mbtz)(btec)_0.5]_n ( 3 ) (mbtz=1,3‐bis(1,2,4‐triazol‐1‐ylmethyl)benzene, btec=1,2,4,5‐benzenetetracarboxylate) were synthesized. In 1 and 2 , two mbtz ligands are wrapped around each other and are held together by Cu(II) atoms to form one‐dimensional double chain. In 3 , each btec ligand connects four Cu(II) atoms through its four carboxylate groups, resulting in a planar two‐dimensional [Cu(btec)_0.5]_n network. The Cu(II) atoms are further coordinated mbtz ligands to fulfil their coordination geometry and construct new [Cu(btec)_0.5(mbtz)]_n network. 2 and 3 further form the three‐dimensional network through the π···π stacking interactions between the mbtz ligands. The thermal stabilities of 1 , 2 and 3 were measured.     

Photoluminescence of 2-(2′-hydroxy-5′-methylbenzoyl)-1,5-diphenylpyrrole in aqueous and β-cyclodextrin environments: manifestation of open and closed conformers

Steady-state fluorometric studies have been performed on 2-(2′-hydroxy-5′-methylbenzoyl)-1,5-diphenylpyrrole (HMBDPP) in aqueous and aqueous β-cyclodextrin (β-CD) environments at ambient temperature. The fluorophore mostly shows a single emission in aqueous solution. Addition of β-CD to the aqueous solution of the fluorophore results in the development of another emission band at higher energy. The difference in the fluorometric behaviour is assigned to a remarkable change in the polarity of the microenvironment within the supramolecular structural environment compared to that of the bulk aqueous phase. Semi-empirical calculation (AM1-SCI) rules out the possibility of intramolecular proton transfer reaction in any of the S₀, S₁ and T₁ states of the fluorophore. It is proposed that HMBDPP exists mostly in the intermolecularly hydrogen-bonded form (open conformer) in aqueous solution while within β-CD environment, it is the intramolecularly hydrogen-bonded form (closed conformer) that predominates.     

Electrochemical and electrocatalytic studies of the N,N′-(1R,2R)-(–)-1,2-cyclohexylenebis(salicylideneiminato)cobalt(II) complex

The electrochemical properties and catalytic activity of a Co(II) complex with the optically active Schiff base derived from (1R,2R)-(–)-cyclohexanediamine and salicylaldehyde have been studied in non-aqueous solutions. When dissolved in deoxygenated non-aqueous solutions, the complex exhibits reversible redox properties for the Co(II)/Co(III) couple. Electrochemical reduction of oxygen and oxidation of cobalt(II) was observed on cyclic voltammograms of solutions containing both dioxygen and the Schiff base-cobalt(II) complex. An anodically formed film on a platinum electrode, studied by means of X-ray photoelectron spectroscopy, revealed the presence of the oxidized Co(III) species. Cyclic voltammetry of oxygenated solutions examined after a period of time indicates an electrochemical activity of coordinated superoxo/peroxo species in the 0.7–1.1 V potential range. In the presence of 4-methyl-1-cyclohexene the cyclic voltammetry curves reveal changes similar to those caused by the removal of oxygen. The GC-MS technique was used to identify some of the products formed by the catalytic oxidation of cyclohexene and 4-methyl-1-cyclohexene. Electronic Publication     

希土元素与三甲胺氧化物配合物的制备及光谱性质

尽管文献报道了三甲胺氧化物与Mn、Co、Ni、Zn、Cd、Cu等多种离子在有机溶剂中形成较稳定的配合物。但对其金属配合物的研究远不如芳香族杂环化合物那样引起人们广泛的注意。本文研究了它与希土元素形成配合物的合成和光谱性质。