Fig. 1: HPIs 1-18 investigated in this study.
From: Hemiphosphoindigos as a platform for chiroptical or water soluble photoswitching
HPIs 1-7 adopt a twisted geometry because of steric hindrance induced by their ortho-substituents. HPIs 8-14 are fully planar and HPIs 15-18 contain a heterocycle with hydrogen bonding capacity. Twisted derivatives are shown on purple background, planar derivatives on blue and heterocyclic derivatives on dark green. Selected corresponding structures in the crystalline state of HPIs 1, 4, 8, and 12 are depicted to illustrate the geometry differences, while the enantiomeric pure structures of planar Z-(R/S)−10 highlight the chiral nature (for all structures determined in the crystalline state see Supplementary Note 16).
