Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO2 surfaces and in thin polymer films

Abstract

Intramolecular conformational dynamics caused by the bay groups of perylene bisimide (PBI) molecules have been investigated by single molecule spectroscopy in thin PMMA polymer films and on SiO2 surfaces. All dynamic processes occur in a jump-like fashion on SiO2 but in a likewise continuous way in PMMA. Surface attachment on SiO2 is accomplished by pyridyl functionalization of PBI demonstrating a nearly perpendicular orientation of the long axis of perylene as has been concluded from polarization experiments. This orientation is subject to fluctuations of the molecular orientation and/or conformation, which are considerably reduced in PMMA. According to static and time-dependent fluorescence spectra at least 2 different conformations have been identified.