ABSTRACT
Multichannel regulable circularly polarized luminescence (CPL) is fascinating because of its fundamental and application interest. There are few reports on helical sense (P-/M-helix) modulation and chiral signal amplification of polyacetylenes with the assistance of achiral polymers and further applications in precisely and conveniently regulating CPL handedness and magnitude. Herein, a helical poly(phenylacetylene)-based CPL-active system was constructed, in which CPL inversion occurred by adding achiral PMMA into a helical poly(phenylacetylene)-CHCl3 solution. Significantly, there is almost 10 times magnification of luminescence dissymmetry factor values (|glum|) during this process. The above phenomena could be ascribed to the PMMA-assisted polyene backbone elongation and the formation of a more ordered helical structure for the poly(phenylacetylene)s. More interestingly, the CPL signal can be facilely inverted and switched by simply changing the thickness of the PPhAD/PMMA layer. The temperature-driven dynamic CPL handedness inversion and magnitude modulation can also be achieved. Based on the multiple regulations for CPL, logic operations were developed, and the practical application is further facilitated by designing various CPL patterns. This study establishes effective and convenient strategies to switch the handedness, magnitude, and wavelength of CPL, which may generate a breakthrough in the manufacturing of CPL-active smart materials and devices with promising application potential.
ABSTRACT
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.
ABSTRACT
The original version of the Article contained an error in Figure 2 in which the TEM images in Fig. 2b and d were incorrect. Additionally, the seventh sentence of the 'Mechanism for the dissymmetry enhancement of SCL field' section of the Methods originally contained a mistake in the first equation. This has been corrected in both the PDF and HTML versions of the Article.
ABSTRACT
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.
