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Revealing the Mechanism of Hydrolysis and Metal Complexation of Kaempferol by Differential Absorbance Spectra and TD-DFT Calculations
HAN Xuze, YAN Mingquan
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (4): 883-889.   DOI: 10.13209/j.0479-8023.2017.117
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In order to reveal the mechanism of hydrolysis and metal complexation of kaempferol, the UV-vis spectra of kaempferol in hydrolysis process (pH from 2.01 to 13.00) and in Cu(II) complexation process (from 0.1 to 2710.9 μmol/L) was obtained, and the characteristic spectra at various reaction stages was obtained by differential treatment. Combined with quantum chemical theoretical computation, a variety of possible deprotonation structures, complexation structures and corresponding electron absorption spectra were calculated based on DFT (Density Functional Theory) and TD-DFT (Time-Dependent Density Functional Theory). The experimental results are compared with the calculated values and it indicates that the hydrolysis process is in the deprotonation order of 7, 4′, 3, 5 phenolic group; at low concentrations of Cu(II) (<67.9 μmol/L), Cu(II) chelated with 4,5 phenolic group simultaneously; at high concentration of Cu(II) (67.9–2710.9 μmol/L), Cu(II) chelated with 3,4 phenolic group simultaneously. The calculated spectra is consistent with experimental spectra in hydrolysis and Cu(II) complexation process of kaempferol. The appearance of characteristic peaks is due to the change of the electron distribution of the active groups before and after hydrolysis and Cu(II) complexation, resulting in the changes of energy gap from HOMO (highest occupied molecular orbital) to LUMO (lowest unoccupied molecular orbital) during photon irradiation. The mechanism of hydrolysis and metal complexation process of kaempferol was revealed.

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Formation Ages, Petrogenesis and Geological Implications of the Archean Granitoid Rocks in the Xinbin-Weiziyu Area, Northern Liaoning Province
WANG Kang, LIU Shuwen, WANG Maojiang, WANG Wei, YAN Ming
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (1): 61-79.   DOI: 10.13209/j.0479-8023.2017.067
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The granitoid rocks in the Xinbin-Weiziyu area, northern Liaoning Province, comprise tonalitictrondhjemitic gneisses and monzogranite-syenogranite plutons. To determine their formation ages and petrogenesis, zircon U-Pb-Hf isotopic analyses and whole-rock geochemical analyses are conducted on these granitoid rocks. LAICP-MS zircon U-Pb isotopic dating data reveal that the tonalitic and trondhjemitic gneisses emplaced at 2588±4 Ma (MSWD=1.3) and 2587±6 Ma (MSWD=1.8), respectively, and the monzogranite-syenogranite intrusions formed at 2555±4 Ma (MSWD=0.51). Whole-rock geochemistry and zircon Lu-Hf isotopes suggest that magmatic precursors of the tonalitic-trondhjemitic gneisses were derived from partial melting of subducted slabs and the magmas were contaminated by the mantle wedge materials during their ascent. Some of the monzogranitesyenogranite plutons were produced by partial melting of metagreywackes, whereas the others were generated by partial melting of a mixed source composed of metabasalts and metasedimentary rocks. Integrated with recent studies, the Neoarchean granitoid rocks in the Xinbin-Weiziyu area may have been generated under an active continental margin.

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