Synthesis, Crystal Structures and Antibacterial Activities of N,N'-Ethylene-bis(3-bromosalicylaldimine) and Its Copper(II) and Cobalt(III) Complexes.

A bis-Schiff base N,N'-ethylene-bis(3-bromosalicylaldimine) (H2L) was prepared from 3-bromosalicylaldehyde and ethane-1,2-diamine. With H2L as ligand, a new copper(II) complex [CuL] (1) and a new cobalt(III) complex [CoL(NCS)(DMF)] (2) were prepared and characterized by physico-chemical methods and single crystal X-ray analysis. X-ray analysis indicates that the Cu atom in complex 1 is in square planar coordination, and the Co atom in complex 2 is in octahedral coordination. The compounds were tested in vitro for their antibacterial activities on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens. Both complexes have effective activities on the bacteria.

Theoretical and experimental research on self-assembly system of molecularly imprinted polymers formed via chloramphenicol and methacrylic acid.

Chloramphenicol was chosen as the imprinting molecule and the methacrylic acid was chosen as the functional monomer to prepare molecularly imprinted polymers. Ethylene glycol dimethacrylate, pentaerythritol triacrylate, and trimethylolpropane trimethylacrylate were used as the cross-linking agents, respectively. The interaction processes between chloramphenicol and methacrylic acid were simulated by using the ωB97XD/6-31G (d,p) method. The self-assembled configuration, bonding sites, binding number, binding energy, and interaction principle of stable complex formed by chloramphenicol and methacrylic acid with different molar ratios have been studied. The selectivity of the most stable complex formed from chloramphenicol and methacrylic acid was discussed with the thiamphenicol and florfenicol as the analogues of chloramphenicol. The results showed that chloramphenicol and methacrylic acid were interacted through the hydrogen bonds. When the molar ratio was 1:10 and pentaerythritol triacrylate as the cross-linking agent, the ordered complex formed by chloramphenicol and methacrylic acid has the largest amount of hydrogen bonds and the lowest binding energy. Scatchard analysis showed that the maximum apparent adsorption capacity was 173.3 mg/g (0.536 mol/g), and the selection factor of florfenicol was the largest. This study provides a reliable theoretical and experimental basis for the design, preparation, and characterization of chloramphenicol molecularly imprinted polymers.

Theoretical and experimental studies on the performances of barbital-imprinted systems.

By using density functional theory, we studied the interaction process between barbital and 2-vinyl-4,6-diamino-1,3,5-triazine in acetonitrile at 333 K. Barbital and 2-vinyl-4,6-diamino-1,3,5-triazine were used as the template and functional monomer, respectively. The molecularly imprinted polymer microspheres containing barbital and 2-vinyl-4,6-diamino-1,3,5-triazine were synthesized through precipitation polymerization. After removing the template molecule barbital, the average diameter of the obtained molecularly imprinted polymers was 1.45 µm. By optimizing the molar ratio of barbital and the 2-vinyl-4,6-diamino-1,3,5-triazine, the resulting molecularly imprinted polymers showed the highest adsorption for the barbital. The analysis of the Scatchard plot revealed that the dissociation constant (Kd ) and apparent maximum adsorption quantity (Qmax ) of the molecularly imprinted polymers were 30.69 mg/L and 8.68 mg/g, respectively. The study of selective adsorption showed that molecularly imprinted polymers exhibited higher selectivity for barbtital than that for 1,3-dimethyl barbituric acid and pentobarbital. Herein, the studies can provide theoretical and experimental references for the barbital-imprinted system.

Preparation of melamine molecularly imprinted polymer by computer-aided design.

Melamine was chosen as template, methacrylic acid was chosen as functional monomer, and divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane trimethylacrylate were chosen as cross-linking agents, respectively. The WB97XD/6-31G(d, p) method was used to calculate the geometry optimization of the different imprinting ratios, the action sites, the bonding situation, and the optimization of the cross-linking agents. The nature of the imprinting effect was also studied by the atoms in molecules theory. The theoretical results showed that melamine interacts with methacrylic acid by hydrogen bonding, and the melamine molecularly imprinted polymers with a molar ratio of 1:6 have the most hydrogen bonds and the most stable structure. Divinylbenzene is the best cross-linking agent for the melamine molecularly imprinted polymers. The melamine molecularly imprinted polymers were synthesized by precipitation polymerization. The results showed that the maximum adsorption capacity for molecularly imprinted polymers towards melamine is 19.84 mg/g, and the adsorption quantity of the polymers to melamine is obviously higher than that of cyromazine, cyanuric acid, and trithiocyanuric in milk. This study could provide theoretical and experimental references for the screening of the imprinting ratio and the cross-linking agent for the given template and monomer system.