Influence of different solvents in the tautomerism of 2, 2 ׳ – bipyridine- 3, 3-diol by DFT method

[2,2′-bipyridyl]-3,3′-diol (BP(OH)2) has two hydrogen bond and can be used as probe for thebiological studies. It produces diketo (DK) tautomer in triplet excited state (T1) by the excitedstate intramolecular proton transfer (ESIPT) process. We investigate its environment changeby simulation of excited state in different solvents by CIS method. It found that DK tautomeris sensitive to solvent polarity and slightly depend to the hydrogen-bonding ability of solvent.