Molecular amplification of photochemical events

The commander–soldier (C–S) concept proposed by the present author is discussed to review photoresponsive systems exhibiting molecular amplification of photochemical events, which are categorized into two groups; the trigger-type and catalysis-type. As exemplified by the surface-assisted photoalignment control of nematic liquid crystals (LCs) as soldier molecules, the trigger-type C–S scheme results intrinsically in marked enhancement of signal/noise ratios and was expanded to achieve the alignment photocontrol of lyotropic LCs, chiral nematic LCs and discotic LCs. The other molecular amplification scheme referred to as the catalysis-type is kicked off by a photogenerated acid- or base-catalyst to bring about the subsequent acid- or base-catalyzed reaction(s), leading to the improvement of photosensitivity. Acid or base proliferation reactions consisting of autocatalytic formation of acidic or basic catalyst molecules are mentioned to highlight their significant roles in improving photosensitivity characteristics of photopolymers consisting of chemical transformations induced by photogenerated acidic or basic species.