文摘
Density functional theory and time-dependent density functional theory were employed to theoretically analyze the effect of different substituents on the spectroscopic properties of furylfulgide. The result shows that the absorption spectra of ring-closed isomer which substituted by an electron-donating group (NH2) at the R3-position of furylfulgide has an evident bathochromic shift compared with the others. Due to the steric hindrance effect, the difference of absorption wavelength was evidently enlarged by introducing several representative electron-withdrawing groups at the R6-position of furylfulgide. In addition, we also designed a series of novel dimers which combined two furylfulgimide monomers into one new molecule. The relevant frontier molecular orbitals, energy levels and absorption properties were analyzed in detail by the calculation of low-lying excited states. Finally, taking BFF-6 (bis-furylfulgimide) for an example, we discussed the transformation mechanism of four stable isomers in the toluene solution. Our conclusions manifest that the asymmetrical BFF-6 can act as a potential multifunctional molecular switch in consideration of its distinguishable absorption bands and reversible conversion process. We hope that this research will be beneficial to design more practical and efficient molecular switch for further applications.