2,5-bis(2 '-benzoxazolyl)hydroquinone (BBHQ), a dually fluorescent ESIPT system revisited: XRD analysis and supersonic jet studies of deuterated species

作者：Vdovin A; Karpiuk E; Lipkowski J; Listkowski A; Kijak M; Grabowska A; Sepiol J^*

来源：Journal of Molecular Structure, 2018, 1171: 843-849.

DOI：10.1016/j.molstruc.2018.06.047

• ESIPT-Molecule
• Dual emission
• X-ray analysis
• Mass selected spectroscopy
• Deuterium substitution effect

The new experimental results of the dually emitting ESIPT molecule, the 2,5-bis(2'-benzoxazolyl)hydroquinone (BBHQ) are presented. The results of the XRD analysis are the following: the unit cell of the monoclinic symmetry contains the perfectly planar BBHQ molecules, with two O-H center dot center dot center dot N intramolecular hydrogen bonds. There are two molecules in the asymmetric part of the cell, one the single BBHQ structure and the other being superposition of the main component with the site occupation factor (sof) 77.4(6)% and the minor one: sof = 22.6(6)%- the same structure rotated by 180 degrees along the long axis of the molecule. The remarkable agreement of the experimentally determined molecular structure with theoretical results reported in the literature, was observed. The dispersed fluorescence spectra of jet cooled molecule, covering two fluorescence bands were measured. It was observed that the intensity ratio of both emissions was dependent on excitation by subsequent quanta of the leading vibration of 114 cm(-1). The height of the barrier separating the two emitting tautomers was estimated as similar to 340 cm(-1). Moreover, the two independent experimental tools, the double-resonance fluorescence depletion (DFD) and mass selected two photon ionization (R2PI) techniques were applied to the partially deuterated jet cooled BBHQ enabling the separation and identification of four different deuterated species, some not known until now.

• 出版日期2018-11-5