Unusual fluorescence emission from ethynyltriphenylene-substituted diacetylenic molecular hinge. Formation of intramolecular excimer.
A diacetylenic molecular hinge bearing two ethynyltriphenylene units (1) has been synthesized. Evidence from (1)H NMR and variable temperature NMR (VT-NMR) of 1 in comparison to model compounds bearing only one triphenylene unit suggests that there is an equilibrium between the open conformer and the intramolecularly pi-pi interacting closed conformer in solution (equilibrium constant K = 6.5 at 298 K in CDCl(3)) arising from the rotation of the diacetylenic hinge. Unusual fluorescence emission observed from 1 has been assigned to excimer formation arising from intramolecularly pi-pi interacting triphenylene units in the excited state. Steady state and picosecond time resolved fluorescence spectra of 1 were nearly identical and corresponded to intramolecular excimer emission.
Nandy
Ritesh
R
Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India.
Sankararaman
Sethuraman
S
D000114:Acetylene / Q000138:chemical synthesis / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010616:Phenanthrenes / Q000737:chemistry*; D013696:Temperature
D000480:Alkynes; D005456:Fluorescent Dyes; D010616:Phenanthrenes; D000114:Acetylene