A New Approach for Studying Bond Rupture/Closure of a Spiro Benzopyran Photochromic Material: Reactivity Descriptors Derived from Frontier Orbitals and DFT Computed Electrostatic Potential Energy Surface Maps

Figure 2

(a) Theoretically computed electronic spectra of the SP (red)/MC [CCC (cyan), TTC (green), and TTT(purple)] isomers. (b) Experimentally determined photo-induced transformation ( nm on the absorption spectrum of  M of SP in toluene). Time of irradiation from the bottom = 0, 10, 20, 30, 40, 60, 90 sec. The sharp isosbestic point in (b) reveals the isomerization reaction between a closed SP and an open merocyanine form.

(a)

(b)