Unique interplay between electronic states and dihedral angle for the molecular rotor diphenyldiacetylene

Peter Waaben Thulstrup, Søren Vrønning Hoffmann, Bjarke Knud Vilster Hansen, Jens Spanget-Larsen

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Abstract

A new analysis of the optical properties of the molecular rotor 1,4-diphenyl-1,3-butadiyne (diphenyl-diacetylene, DPDA) is presented, taking account of the conformational dynamics. The absorption spectra are interpreted in terms of simultaneous contributions from planar as well as non-planar rotamers, characterized by a temperature dependent equilibrium distribution. The investigation is based on IR Linear Dichroism and UV Synchrotron Radiation Linear Dichroism (SRLD) spectroscopy on oriented samples in stretched polyethylene (PE), and on variable temperature UV spectroscopy. The study is supported by the results of detailed quantum chemical Time Dependent Density Functional Theory (TD-DFT) calculations. The resulting analysis has profound implications for the understanding of the optical, photochemical, and photophysical characteristics of this and related chromophores, of importance in a variety of applications.

Original languageEnglish
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number36
Pages (from-to)16168-16174
Number of pages7
ISSN1463-9076
DOIs
Publication statusPublished - 2011

Keywords

  • molecular rotors
  • diarylpolyynes
  • synchrotron radiation
  • linear dichroism (LD)
  • electronic transitions
  • UV spectroscopy
  • FTIR spectroscopy
  • polarization directions

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