Existence of intramolecular triplet excimer of bis(9-fluorenyl)methane: phosphorescence and delayed fluorescence spectroscopic and ab initio studies.
A concerted computational and experimental study has been undertaken to probe the conformational structure and excited-state dynamics of bis(9-fluorenyl)methane (BFM). We have observed that the relative intensity of the delayed excimer fluorescence of BFM is greatly enhanced in comparison with that of the normal fluorescence. This is presumably because the relative concentration of the triplet excimer is enhanced in comparison with the singlet excimer. B3LYP DFT/6-31G(d) calculations indicate that the sandwich conformer of BFM in the singlet ground state is unstable, whereas that in the triplet excited state has a bound state, being very slightly higher in internal and Gibbs free energies than that of the lowest state of the near-orthogonal conformer.
Kang
Heun Kag
HK
Department of Chemistry, Chungnam National University, Daejeon 305-764, Korea.
Kang
Dong Eun
DE
Boo
Bong Hyun
BH
Yoo
Suk Jae
SJ
Lee
Jae Kwang
JK
Lim
Edward C
EC