Multistate Chiroptical Switch Triggered by Stimuli-Responsive Chiral Teleinduction

This is the Accepted Manuscript version of a Published Work that appeared in final form in Chemistry of Materials, Copyright © 2018 American Chemical Society after peer review and technical edityng by the publisher. To access the final edited and published work see: https://pubs.acs.org/doi/10.1021/acs.chemmater.8b00800Teleinduction of chirality, from a distant chiral center in the pendant, to the helical backbone of a poly(phenylacetylene) (PPA) was demonstrated by using an achiral, flexible and well-organized spacer originating a multistate chiroptical switch. Two PPA series, with pendants formed by one or two consecutive Gly residues C-attached to the PPA backbone and N-attached to (R)- or (S)-α- methoxy-α-trifluormethylacetic acid (MTPA), were prepared and the changes in the helical contain upon modification of the MTPA conformation by external stimuli (i.e., polarity of the media, metal cations) were examined. Chiral teleinduction, imposing opposite helicities, was observed in the two polymer series due to the parallel β-sheet arrangements of the Gly residues orienting the chiral groups in specific directions along the external part of the helices. This teleinduction can be tuned inducing either the P or M helical sense of the polymer by controlled conformational changes on the chiral moiety attached to the achiral β-sheet spacer. This remote control of the helix can be switched On/Off by favoring/disfavoring the β-sheet arrangement of the Gly residues resorting to changes on the temperature and the addition of destabilizing agents (e.g., TFA)Financial support from MINECO (CTQ2014-61470-EXP, CTQ2015- 70519-P), Xunta de Galicia (GRC2014/040, Centro singular de investigación de Galicia accreditation 2016-2019, ED431G/09) and the European Regional Development Fund (ERDF) is gratefully acknowledged. R. R. is grateful to MINECO for a FPI predoctoral fellowshipS