Fig. 3: Crystal structure and theoretical calculation.

a The ethylene double bond length and the twist angle between benzene rings of Z-H (up) and E-H (down). b Single-crystal structure and intermolecular interaction of Z-H (up) and E-H (down). c The calculated absorption wavelength of Z-H-P with uB3LYP functional at the basis set level of 6–31 g(d). d Computed Mulliken atomic spin densities for compound Z-H-P and visualized total spin density.