Photoisomerization by hula-twist: a fundamental supramolecular photochemical reaction.
The volume-conserving hula-twist cis/trans isomerization process has been incorporated in a general scheme for photoisomerization of polyenes, applicable to small organic molecules as well as to protein-bound polyene chromophores. The main theme is that in solution the conventional one-bond-flip mechanism dominates, while in frozen media (or under other forms of supramolecular constraint) the hula-twist mechanism takes over. Literature examples of photoisomerization obtained under confined conditions have been critically reviewed, the applicability of HT has been examined, and new systems unambiguously testing this volume-conserving process are proposed.
Liu
R S
RS
Department of Chemistry, University of Hawaii, 2545 The Mall, Honolulu, Hawaii 96822, USA. rliu@gold.chem.hawaii.edu
D007536:Isomerism; D010777:Photochemistry / Q000379:methods*; D011090:Polyenes / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry
D011090:Polyenes; D011506:Proteins