We have studied the ground and excited states of the three dendritic polynuclear Pt(II) complexes 1-[Cl(PH3)2PtC≡≡ C]-3,5-[HC≡≡ C]C6H3 (1), 1,3-[Cl(PH3)2PtC≡≡ C]2-5-[HC≡≡ C]C6H3 (2), and 1,3,5-[Cl(PH3)2- PtC≡≡ C]3C6H3 (3), by using the B3LYP and UB3LYP methods, respectively. TDDFT approach with the PCM model was performed to predict the emission spectra properties of 1―3 in CH2Cl2 solution. We first predicted the excited-state geometries for the three complexes. With the change of the number of Pt(II) atom, 1―3 show the different geometry structures in both the ground and excited states; fur- thermore, the increase of the metal density from 1 to 3 results in the red shift of the lowest-energy emissions along the series. The luminescent properties of 1 are somewhat different from those of 2 and 3. The emission properties of 2 and 3 are richer than 1. Our conclusion can give a good support for designing the high efficient luminescent materials.
ZHOU Xin1, PAN QingJiang2, LI MingXia1,2, ZHANG HongXing1 & Tang AuChin1 1 State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
With density functional theory（DFT） and molecular mechanics method, the catalytic mechanism of silent information regulator（sirtuins） has been investigated. The calculations support the SN2-1ike reaction of the initial step of the catalysis, and are consistent with experiment results. We further explored the second step of the catalysis and proposed that this step took place in a concerted reaction. In addition, the side chain of Phenylalanine33 may help to shield the glycosidic bond from water and be in a position to protect the developing oxacabenium transition state from hydrolysis. Our results of the calculations support this hypothesis that the phenylalanine33 plays a critical role in the sirtuins biology function.
