Hindrance of the rotational relaxation in the excited singlet state of biphenyl and para-terphenyl in cooled solutions by methyl substituents

Conformational rearrangements in and twisting of a single molecule

“…where I p1 and I p2 are the intensities of, respectively, the ®rst and the second peak in the spectrum and I v is the intensity of the valley between the peaks [21]. A low value of S corresponds to a spectrum with a clear ®ne structure, a high value of S to an unstructured spectrum.…”

Low-temperature photoluminescence of 5CB liquid crystal

“…Probably, these two non-equivalent states of the 5CB molecules in a crystal explain the presence of two spectral components in the 5CB luminescence spectra, 343 and 360 nm, corresponding to the monomer emission. This can be supported by a potential model, proposed by Rapp and co-workers [27] to explain the appearance and loss of fine structure in the 9CB luminescence spectra. This model accounts for steric hindrance to planarity at certain temperatures and the intramolecular twisting relaxation towards planarity at other temperatures.…”

Ultrafast bimolecular radical reaction between S1p‐terphenyl and carbon tetrachloride: mode‐specific acceleration of vibrational dephasing in reactant molecule

“…The dihedral angles between the two phenyl rings in solution, for example, have not been precisely determined either in the electronic ground state or in the excited states, although it is believed from experimental 19 -25 and theoretical 26 -29 studies that the molecule in solutions has a twisted form in the ground state 19 -30 and a planar form in the S 1 state. 24,25,29 A recent study with density functional calculation by Honda and Furukawa 30 shows that the molecule in the ground state has two stable isomers, helical and twisted, with the common dihedral angle of 40.5°. p-Terphenyl is also regarded as a key molecule that connects benzene or biphenyl and poly-p-phenylene.…”