We investigate the conformational stabilities, dipole moments, bond lengths and partial charges of photosensitive spiropyran (1',3'-dihydro-1',3',3'-trimethyl-6-nitro-spiro[2H-1-benzopyran-2,2'-[2H]indole]) after its photo-switching to the open form conformers, merocyanine and its protonated counterparts. Two approaches, an ab initio Hartree-Fock method supplemented by the Moller-Plesset second-order perturbation theory and density functional theory under B3LYP parameterization, are employed with extended basis sets to examine the energetic ordering of the conformers in vacuum and in an aqueous environment. The influence of the solvent on the conformers is demonstrated by the notable changes in the structural and electrostatic properties. (C) 2015 Elsevier B.V. All rights reserved.