Near-Infrared Circularly Polarized Light Triggered Enantioselective Photopolymerization by Using Upconversion Nanophosphors

5 years ago

Near-Infrared Circularly Polarized Light Triggered Enantioselective Photopolymerization by Using Upconversion Nanophosphors

Qijin Zhang, Dong Qiu, Jingang Hu, Liangfu Zhu, Hongyan Xia, Gang Zou, Douguo Zhang, Guang Yang

Circularly polarized light (CPL) is considered to be a true chiral entity and has been suggested as an explanation for the introduction of initial chiral biases into key biomolecular building blocks. CPL used recently asymmetric photochemical reactions is of wavelengths mainly in the UV and visible regions, whereas natural CPL observed in star-forming regions of the Orion constellation falls in the IR region. Whether CPL in the IR or near-IR region could be utilized to trigger asymmetric photochemical reactions remains to be determined. Herein, it is demonstrated that enantioselective photopolymerization can be realized by using λ=980 nm CPL as the only chiral source. By incorporating NaYF4 nanophosphors as the antenna species, the enantioselective photopolymerization of achiral benzaldehyde-substituted diacetylene monomer can be realized based on an upconversion mechanism upon exposure to λ=980 nm CPL. The screw direction of the helical PDA chains can be completely controlled by the handedness of incident λ=980 nm CPL. Transferring information: The inherent chirality of λ=980 nm circularly polarized light (CPL) could be transferred to upconversion luminescence (UCL) from lanthanide-doped upconversion nanoparticles (UCNPs), making it possible to realize near-IR CPL triggered enantioselective photopolymerization by incorporating UCNPs as antenna species (see figure). The screw direction of the formed helical polymer chains is the same as the handedness of the incident λ=980 nm CPL.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201700823