Zhu Zhi-Ang

Molecular Recognition of Chiral Zinc Porphyrin with Amino Acid Ester Derivatives

Molecular recognition of chiral zinc porphyrin [p-(L-Leu)C2O-TPPZn] with amino acid ester derivatives was investigated by UV-Vis spectrophotometric titration and CD spectroscopy. The experimental results suggested that the association constant was KDKL for amino acid ester derivatives, and then increased following the order of K(AlaOCH3)K(ValOCH3)K(LeuOCH3)K(PheOCH3). CD spectroscopy had also been used in order to elucidate the conformation of the host-guest complex, different chiral environments could come into being from CD spectroscopy when different guests coordinated to host. Moreover, the minimum energy conformations of the host-guest system were obtained by simulated annealing, and it was found that there was π-π* interaction between host and D,L-PheOCH3.

Kinetic studies on axial coordination reactions of para-substituted tetraphenylporphinatoiron(III) chlorides

Abstract A series of para-substituted tetraphenylporphinatoiron(III) chlorides [(p-X)TPPFeCl] (XCl, H, CH3, OCH3) have been synthesized. Kinetic studies are reported for the reactions of (p-X)TPPFeCl+nL→ (p-X)TPPFeLn]+Cl− (L=imidazole, 2-methylimidazole and 2-ethyl-4-methyl-imidazole) in acetone at several temperatures. The reaction rates are second order dependent on Im and MeIm with n=2, but first order on EMIm with n=1; the reaction rates increase with temperature in both cases. The mechanisms of reactions for various ligands have been proposed. The effects of various ligands and para-substituents on the phenyl rings for these reactions have been investigated.

Weak Interactions in Asymmetric Porphyrin Systems

The weak interactions of 5-imidazolylmethylphenyl-10,15,20-tri-tert-butylphenylporphyrin (1) and 5-imidazolylmethylphenyl-10,15,20-triphenylporphyrin (2) were investigated in chloroform by 1H NMR, UV-Vis and fluorescence spectroscopies, and molecular modeling simulation. The 1H NMR chemical shifts of imidazole in compounds 1 and 2 move upfield compared with that of free imidazole and this shows that intramolecular or intermolecular weak interactions exist in both compounds. Compared with the UV-Vis spectra of compounds 1 and 2 in acetone, their spectra in chloroform show a split Soret band for compound 1, which indicates a weak intramolecular interaction and a red shift of 27 nm for compound 2, which also suggests a weak intermolecular interaction. The fluorescence data supports these results and the data obtained from the molecular simulation are consistent with those of the spectral analyses.