Ab initio calculations of the absorption spectrum of chalcone

摘要

The excitation energies and excited states of trans-chalcone 9trans-(s-cis)-1,3-diphenylpropenone), and several related molecules (trans-(s-cis)-3-phenylpropenal, s-cis-1-phenylpropenone, propenal, trans-(s-cis)-1-(4-hydroxyphenyl)-3-phenylpropenone, trans-(s-cis)3-(4-hydroxyphenyl)-1-phenylpropenone) have been calculated using single reference ab initio molecular orbital methods, and characterized by attachment-detachment density analysis. The results suggest assignments for the lowest three electronic transitions observed experimentally for trans-(s-cis)-chalcone in solution. The extent of localization of the electronic transitions is established by calculations on the excited states of trans-(s-cis)-3-phenylpropenal, s-cis-1-phenylpropenone and propenal, as well as analysis of the chalcone calculations. Contrary to some previous work, none of these excitations are strongly delocalized over the entire molecule. Calculated substituent shifts for the hydroxy chalcones are in qualitative agreement with experimental data, and support the localized interpretation of the main #pi#->#pi#* transition.