Superchiral light, generated by the interference of two counter-propagating circularly polarized light (CPL) with same frequency, opposite handedness and different intensity, exhibits enhanced dissymmetry in its interaction with chiral molecules, and has the potential for ultrasensitive detection and characterization of chiral molecules. It is anticipated that the enhanced optical dissymmetry in superchiral light (SCL) field may be utilized to promote asymmetric photochemical reactions efficiency. Herein we reported SCL impart greater chiral bias to trigger asymmetric photo-polymerization reaction from initially achiral diacetylene (DA) monomer, and the enhanced optical dissymmetry for whole polydiacetylene (PDA) films could be achieved. An explanation based on the chiral transfer and amplification of chiral bias from SCL during the polymerization process has been proposed. Moreover, thus formed chiral PDA films polymerized by SCL exhibited enhanced enantioselective recognition ability, and can serve as a direct visual probe for the discrimination of some specific enantiomers.

Studies on the following were reviewed: (1) the structure of spiropyrans and spirooxazines (two kinds of spiro compounds) under external stimuli and (2) the construction and applications of composite systems based on fluorescence resonance energy transfer (FRET) with fluorescent materials. When treated with different stimuli (light, acids and bases, solvents, metal ions, temperature, redox potential, and so on), spiropyrans/spirooxazines undergo transformations between the ring-closed form (SP), the ring-opened merocyanine (MC) form, and the protonated ring-opened form (MCH). This is due to the breakage of the spiro C–O bond and the protonation of MC, along with a color change. Various novel, multifunctional materials based on photochromic spiropyrans and spirooxazines have been successfully developed because of the vastly differently physiochemical properties posssed by the SP, MC and MCH forms. Among the three different structural forms, the MC form has been studied most extensively. The MC form not only gives complexes with various inorganic particles, biological molecules, and organic chemicals but also acts as the energy acceptor (of energy from fluorescent molecules) during energy transfer processes that take place under proper conditions. Furthermore, spiropyran and spirooxazine compounds exhibit reversible physicochemical property changes under proper stimuli; this provides more advantages compared with other photochromic compounds. Additionally, the molecular structures of spiropyrans and spirooxazines can be easily modified and extended, so better compounds can be obtained to expand the scope of already known applications. Described in detail are: (1) the structural properties of spiropyrans and spirooxazines and related photochromic mechanisms; (2) composite systems based on spiropyrans and spirooxazines, and (3) fluorescent materials which have potential applications in sensing, probing, and a variety of optical elements.

Herein, photo-controlled inclusion and exclusion reaction of azobenzene-containing polydiacetylene vesicles with α-cyclodextrin were used to act as driving force to induce chromatic transition of PDA vesicles, which provided a novel model system that combines photochemistry and host–guest chemistry for a photo-stimulus-responsive vesicle.

Chiral noble metal nanoparticles has recently gained great interest due to their potential applications including ultrasensitive chiral recognition and asymmetric synthesis. We anticipate that they could be utilized to induce asymmetric photo-polymerization reactions with high enantioselectivity and reactivity. Here, we report such a system. By employing silver nanoparticles modified with cysteine as the chiral inducer, polydiacetylene (PDA) with high chiral asymmetry was obtained from achiral diacetylene monomers triggered with unpolarized UV light. Furthermore, the helical sense of chirality can be controlled by varying the wavelength of UV irradiation. This enables a feasible and economical method to fabricate programmable 2D patterns of chiral PDA with tailored chirality distributions, such as smooth gradients in chirality and micropatterns with tailorable circularly polarized luminescence. Our finding not only opens a pathway for producing programmable chiroptical micropatterns, but also is highly valuable for deeper understanding of symmetry breaking in enantioselective photochemical reactions.