Solvent Effects on Charge-transfer Fluorescence Bands

摘要: CHARGE-TRANSFER (CT) transitions in complexes with an ionic ground state, leading as they do to annihilation of the charge, are particularly sensitive polarity solvent. Such have been used derive empirical solvent parameters Z (ref. 1) and ET 2) which correlate well transition energies other charged states3–5. Complexes state is non-ionic show, on hand, little correlation between energy charge-transfer (or Z), because Franck–Condon restriction reorganization during transition. The CT fluorescence such should, however, provided that lifetime excited sufficient allow should thus decrease increase polarity, reverse trend observed for absorption process. Few found fluoresce fluid solution6,7, these only a few solvents, mainly very low polarity. band maxima measured range solvents using Baird-Atomic SF100 spectrofluorimeter complex hexamethylbenzene–tetrachlorophthalic anhydride shown Table 1, Fig. 1 plot energy, ECT, against parameter, ET. A good straight line slope close unity (0.91) obtained, showing stabilization similar complexes.