Theoretical Investigation of the ESIPT Mechanism for the 1-Hydroxy-9H-fluoren-9-one and 1-Hydroxy-11H-benzo[b]fluoren-11-one Chromophores

• DOI: 10.1007/s10876-016-1122-8
• Publication Date: 2016-11-26T14:17:31Z
• Authors: Meixia Zhang; Qiao Zhou; Mengru Zhang; Yumei Dai; Peng Song; Yi Jiang
• Keywords: 7. Clean energy; 01 natural sciences; 0104 chemical sciences

The excited state intramolecular proton transfer (ESIPT) dynamics of the 1-hydroxy-9H-fluoren-9-one (HHF) and 1-hydroxy-11H-benzo[b]fluoren-11-one (HHBF) chromophores were investigated theoretically. The calculated bond lengths and angles, hydrogen bond energies and infrared vibrational spectra involved in the hydrogen bonding of O–H···O indicated that the intramolecular hydrogen bond was strengthened in the S1 state. Our calculated results accurately reproduced the experimental absorbance and fluorescence emission spectra, demonstrating that the adopted time-dependent density functional theory (TDDFT) method is reasonable and effective. In addition, qualitative and quantitative intramolecular charge transfer based on the frontier molecular orbitals provided the possibility of the ESIPT reaction. The potential energy curves of the ground and first excited states have been constructed to illustrate the ESIPT mechanism. Based on our calculations, we explain the equilibrium ESIPT processes observed in previous experiments.