Construction of Chiroptical Switch on Silica Nanopartide Surface via Chiral Self-assembly of Side-chain Azobenzene-containing Polymer

In this contribution,we utilized surface initiated atom transfer radical polymerization(SI-ATRP)to prepare organicinorganic hybrid core/shell silila nanoparticles(NPs),where silia particles acted as cores and polymeric shells(PAzoMA*)were attached to silica particles via covalent bond.Subsequently,chiroptical switch was sccessfully constructed on silica NPs surface taking advantage of supramolecular chiral self-assembly of the grafted side chain Azo-containing polymer(PAzoMA*).We found that the supramolecular chirality was highly dependent on the molecular weight of grafted PAzoMA*.Meanwhile,the supramolecular chirality could be regulated using 365 nm UV light iradiation and heating cooling treatment,and a reversible supramolecular chiroptical switch could be repeated for over five cycles on silia NPs surface.Moreover,when heated above the glass transition temperature(T_(g))of PAzoMA",the organic-inorganic hybrid nanoparticles(SiO_(2)@PAzoMA*NPs)still exhibited intense DRCD signals.Interestingly,the supramolecular chirality could be retained in solid film for more than 3 months.To conclude,we have prepared an organic inorganic hybrid core/shell chiral slia nanomaterial with dynamic reversible chirality,thermal stability and chiral storage functions,providing potential applications in dynamic asymmetric catalysis,chiral separation and so on.