Quantitative structure-property relationship modeling of beta-cyclodextrin complexation free energies

CODESSA-PRO was used to model binding energies for 1:1 complexation systems between 218 organic guest molecules and beta-cyclodextrin, using a seven-parameter equation with R2 = 0.796 and Rcv2 = 0.779. Fragment-based TRAIL calculations gave a better fit with R2 = 0.943 and Rcv2 = 0.848 for 195 data points in the database. The advantages and disadvantages of each approach are discussed, and it is concluded that a combination of the two approaches has much promise from a practical viewpoint.     

Synthesis and trivalent lanthanide ion complexation studies of new macrocyclic receptors based lactam ionophores

This study is the first report on the design, synthesis and photophysical properties of three new macrocyclic receptors based receptors containing two amide bridges. Their binding properties towards trivalent lanthanide ions such as La³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Er³⁺ and Yb³⁺ were investigated by using spectroscopic techniques. With respect to emission intensity changes upon trivalent lanthanide ion complexation, macrocyclic receptors based lactam ionophores showed higher selectivity towards Yb³⁺ and/or Er³⁺ ion over other ions. Presence of proximal two amide groups in macrocyclic lactam receptors having different cavity size were observed to play an important role in exhibiting its lanthanide ion binding.     

醇类化合物热值改进剂的定量结构-性质关系研究

醇类化合物燃料作为一种新型的可再生清洁能源,目前是代替燃油及煤的优良环保型燃料.本文计算表征了醇类化合物热值改进剂的4个分子连接性指数和5个量子化学参数,用多元线性回归方法对参数进行了优化筛选,获得了醇类化合物热值改进剂的定量结构与热值性质的关系模型,其相关系数R为0.961.计算结果表明:与醇类化合物热值改进剂的热值显著相关的变量是最低空轨道能量ELUMO、最低空轨道能量与最高占有轨道能量差△E、总能量ET,预测值与相应的实验值较好吻合,所建模型具有良好稳定性和预测能力,与分子连接性指数等的相关程度较好.     

Synthesis and metal ion complexation studies of proton-ionizable calix

A series of novel N-chromogenic calix[4]arene azacrown ethers were synthesized as selective extractants of potassium ion. 1,3-Alternate calix[4]arene azacrown ethers were prepared by reacting 25,27-dipropyloxy-26,28-bis(5-chloro-3-oxapentyloxy) calix[4]arenes with p-toluenesulfonamide in the presence of potassium carbonate. The coupling reaction of calix[4]arene azacrown ether with 2-hydroxy-5-nitrobenzyl bromide in the presence of triethylamine in THF gave the chromogenic calix[4]arene azacrown ether in moderate yield. These compounds show high potassium selectivity over other metal ions as shown by two-phase extraction, bulk liquid membrane, and 1H NMR studies on a ligand-metal complex. It is assumed that the OH of the chromogenic group attached on nitrogen can assist the complexation by encapsulation of the metal.     

Modes of complexation of bis-aminals of linear tetraamines with Group 6 metal carbonyls

On reaction with Group 6 metal carbonyls M(CO)₆, vic type bis-aminals L, issued from the condensation of an α-dicarbonyl compound on a linear tetraamine, give rise to mononuclear cis-M(CO)₄L complexes.     

Dissociation and complexation constants of some β-diketone ionophores

The dissociation constants of dibenzoylmethane (DBM), 1-phenyl-3-(p-chlorophenyl)-1,3-propanedion (ETH 245) and 1,13-bis-[4-(3-phenyl-1,3-dioxopropyl)-phenyl]-tridecan (ETH 1224) were potentiometrically evaluated in 80% dioxane medium at 30 °C. The stability constants of DBM complexes with calcium, magnesium and barium as well as those of ETH 245 with magnesium were determined and correlated with the selectivity coefficients of ion-selective electrodes containing DBM as ionophore.     

Synthesis, characterization and structure-property relationship studies of cobaloximes with dithienylglyoxime as the equatorial ligand

The synthesis of cobaloximes, X/RCo(dThgH)₂Py (X = Cl, R = Me, Et, n-Pr, n-Bu and Bn) has been described. All the complexes have been characterized by elemental analyses and NMR spectral studies. The molecular structures of ClCo(dThgH)₂Py, MeCo(dThgH)₂Py, EtCo(dThgH)₂Py and BnCo(dThgH)₂Py complexes are determined by X-ray crystallography. The electron withdrawing nature of 2-thienyl ring affects the NMR as well as electrochemical behavior of these complexes. The electrochemical reduction from Co(III) to Co(II) and from Co(II) to Co(I) are much easier in ClCo(dThgH)₂Py as compared to chlorocobaloximes with the other dioximes (gH, dmgH, dpgH, dmestgH). The molecular oxygen insertion in the Co−C bond of benzyl complex (6) has been examined and a comparison of its reaction rate with other similar cobaloximes is discussed. The structural features of a dioxy complex Bn(O₂)Co(dThgH)₂Py (7) have also been reported.