Fluorescence and Fluorescence Excitation Spectroscopy of 5,8-Dihydroxy-l,4-naphtho-quinone. Analysis of the Electronic Spectra via the Time-Dependent DFT Calculation

摘要

Excited-state intramolecular proton transfer (ESBPT) has been a research topic of incessant and wide interest because of its importance in many photophysical, photochemical, biological processes, and a wide range of application, such as fluorescence molecular probes, luminescent materials, and advanced polymer devices for lasing, optical storage, and electroluminescence. 5,8-Dihydroxy-l,4-naphthoquinone (DHNQ) is one of the simple and ideal molecules for the theoretical elucidation of the photophysical and photochemical processes occurring near the lowest excitation energy. It is quite intriguing to elucidate the molecular orbitals located near the HOMO and LUMO levels in conjunction with specific photochemical processes, and to estimate the intramolecular hydrogen bond strength on the basis of the MO. Ground-state intramolecular proton transfer was studied before, indicating that there are double minima, and the energy to cross over the barrier separating the double minima is found to be high.