Quantum-chemical calculation of electrooptical properties of vanillin tautomers

Static dipole polarizabilities and hyperpolarizabilities of benzoid and p-quinoid molecular forms of vanillin were calculated using quantum-chemical method B3LYP/cc-pVTZ. The dominant benzoid tautomers much exceed in hyperpolarizability the m-nitroaniline molecule. Tautomeric transformations and conformational changes significantly affect the vanillin hyperpolarizability. Quinoid tautomers generated by the topochemical reaction of proton transfer between neighboring molecules in a vanillin crystal can promote the second harmonic generation of infrared laser light only as an element of supramolecular nanostructures (linear defects) with a high hyperpolarizability.