Ab initioinvestigation of the structures and energies of spiropyran and merocyanine isomers

The structures and energies of a set of spiropyrans and merocyanines – BIPS [1 ,3 ,3 -trimethylspiro[2H-1-benzopyran-2,2 - indoline], 6-nitroBIPS, and 6,8-dinitroBIPS – are calculated using density functional theory and second-order Møller–Plesset methods. The relative energies of all possible merocyanine isomers in the ground state are determined systematically at a uniform level of theory. Solvent contributions, which have been found to be significant, are also included. KeThis research was undertaken on the NCI National Facility in Canberra, Australia, which is supported by the Australian Commonwealth Government