Wang Gp

Synthesis, Crystal Structure, Stacking Effect and Antibacterial Studies of a Novel Quaternary Copper (II) Complex with Quinolone

The structural properties of a new copper (II) complex [Cu2(cip)2(bpy)2(pip)]·6H2O (bpy=2,2’-bipyridyl, cip=1-cyclopropyl-6-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, pip= piperazinyl anion), obtained during the synthesis of the copper complex with ciprofloxacin (cpf), has been investigated. The complex crystallizes in the triclinic system, space group P-1. The cell dimensions are: a=6.874(2) Å, b= 10.761(3) Å, c= 17.969(5) Å, α=80.071(6)°, β= 85.253(6)°, γ=79.109(6)°，V=1284.5(6) Å3, and Z=2. The Cu (II) ion displays a five-coordinate square pyramidal coordination with two nitrogen donors from bpy, the 4-keto and 3-carboxylate oxygen donors of cip, and the third nitrogen atom of the pip anion occupying the fifth site. There is a stack effect between cip ring and bpy ring from another molecule, where the stacking distance is about 3.5 Å. The results of elemental analysis and FT-IR measurement are also included. Both ligand and complex were assayed against gram-positive and gram-negative bacteria by the doubling dilutions method. The complex shows the same minimal inhibitory concentration (MIC) against S. Aureus and E. Coli bacteria as the corresponding ligand.

Predicting blood–brain barrier penetration from molecular weight and number of polar atoms

A simple three-descriptor model to predict blood-brain barrier is derived from a training set of 78 compounds: logBB=-9.880 x 10(-6)M(W)(2)+7.339 x 10(-3)M(W)-0.2268n(pol)-0.1143 (n=78, r(2)=0.74), where logBB is the logarithm of the ratio of the steady-state concentration of the compound in the brain to concentration in the blood, M(W) is the molecular weight, n(pol) is the number of polar atoms (oxygen, nitrogen, and attached hydrogen), n is the number of compounds, and r is the correlation coefficient. The model is validated through use of leave-one-out procedure and an external test set (25 compounds). The model is suitable for the rapid prediction of the blood-brain barrier penetration of drug candidates because of its predictive ability and simplicity.

ESR spectral studies of a Cu(II) salicylidene tyrosine complex

A novel Schiff base derived from salicylidene and tyrosine and its copper(II) complex have been synthesized and characterized. The composition of the complex is K[CuL(Ac)] · H2O, where L = H13C16NO4. Electron spin resonance (ESR) spectra of the copper(II) complex were investigated at different temperatures and in various solvents. The second-order effect and the relaxation effect were observed in the solution spectrum at room temperature and satisfactorily explained by the spin Hamiltonian. The bonding parameters of the Cu(II) complex were calculated with spectral parameters from ESR spectra at low temperature. Its bonding characterization and stability were discussed. The result shows that both the in-plane σ-bond and the in-plane π-bond in the complex play an important role.