Ground and excited-state intramolecular interactions in phenol-olefin bichromophoric compounds

The intramolecular OH ... pi interactions of the phenolic and olefinic chromophores in o-propenyl and o-butenyl phenols 1a-d in the ground and excited states have been studied by (a) ab initio Hartree-Fock calculations using the 3-21G and 6-31G** basis sets, (b) FTIR spectral measurements in the gas phase, (c) fluorescence emission studies and (d) product studies. Such interactions appear to play a key role in the photochemical behaviour of the four compounds.