Excited-state Intramolecular Proton Transfer of 1,5- and 1,8-Dihydroxyanthraquinones Chemically Adsorpted onto SiO2,SiO2-Al2O3,and Al2O3 Matrices

摘要

In order to investigate the excited-state intramolecular proton transfer (ESIPT) process of dihydroxyanthraqui-nones (DHAQ;1,5-DHAQ and 1,8-DHAQ) in organic-inorganic hybrid matrices,transparent SiO2,SiO2-Al2O3,and Al2O3 matrices chemically bonded with DHAQ were prepared using a sol-gel technique.The absorption maxima of 1,5- and 1,8-DHAQ in SiO2 matrices are observed at around 420 nm,whereas those of DHAQ in both SiO2-Al2O3 and Al2O3 matrices are markedly shifted to longer wavelength compared with those in SiO2matrix.This indicates that DAHQ forms a chemical bond with an Al atom of Al2O3.The DHAQ in SiO2 matrix shows a markedly Stokes-shifted emission which is originated from the ESIPT in DHAQ.Based on the emission lifetimes of DHAQ,the ESIPT of DHAQ was found to be strongly affected by the chemical interaction with Al atom in the AlO3-related matrices.