Tuning the helical sense and elongation of polymers through the combined action of the two components of tetraalkylammonium-anion salts

The helical sense and elongation of a polymer that bears the 4-ethynylanilide (R)-α‑methoxy-α-phenylacetic acid [m-(R)-1] can be tuned by action two components tetraalkylammonium-anion salts. Thus, while supramolecular PPA-anilide/anion interaction creates chiroptical switch, inducing either P or M senses in poly(phenylacetylene) (PPA) depending on nature anion —P helix: fluoride (F−) cyanide (CN−); acetate (OAc−), benzoate (OBz−) azide (N3−)—, deprotonation anilide group these anions dry conditions makes it possible to play with PPA, size tetraalkylammonium group, which results colorimetric switch. color change from yellow deep red is obtained when tetraabutylammonium salt used, yellow/light-red yellow/orange changes are reduced. Structural mechanistic studies confirm occurs counterion accommodates itself close pendant once hydrogen removed. This PPA/tetraalkylammonium association responsible PPA therefore conjugation polyene backbone accompanied changes. Moreover, this switch also operates solid state switched vacuum/air moisture cycle.