S. Schneider et al., SURFACE-ENHANCED RESONANCE RAMAN STUDIES OF SPIROPYRANS (BIPS AND DERIVATIVES), Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals, 246, 1994, pp. 267-274
The merocyanine form of DIPS and three of its nitro derivatives were s
tudied by surface-enhanced Raman spectroscopy. It was found that in ca
se of the nitro derivates, the SERS spectra originated from the unprot
onated open merocyanine forms, even if the solution was acidified. In
case of 6-nitro BIPS, there exist two enantiomers of the closed spiro
form with different properties. The photoinduced merocyanine form of t
he photoactive enantiomer is different from the thermal ring opening p
roduct of the photoinactive enantiomer.