IR spectrum of the closed form of indolinospironaphthooxazine

IR absorption spectra of indolinospironaphthooxazine (ISNO) are presented. The geometric structure and normal coordinates of the ISNO molecule have been calculated using a quantum mechanical DFT method. The IR spectrum of ISNO in its original spiro form has been interpreted for the first time. Four normal modes in the range 800–1200 cm^–1 with the largest amplitudes of C_spiro–O bond change are identified. The excited ISNO molecule spiro form may experience photoconversion to the merocyanine form through them.