The distinguishing of cis–trans isomers enabled via dielectric/ferroelectric signal feedback in a supramolecular Cu(1,10-phenanthroline)2SeO4·(diol) system

Abstract

Ferroelectric polarization is sensitive to external stimuli, such as temperature or pressure, the variation of which can induce a slight change in crystal structure. Similarly, for ferroelectric crystals in host–guest systems, the inclusion of different guest molecules can affect the crystal packing a small amount; however, it may alter the ferroelectric properties significantly. In this report, we discovered that the supramolecular host–guest system Cu(1,10-phen)₂SeO₄·(diol) (phen is the abbreviation of phenanthroline) can distinguish cis–trans isomers via physical signal feedback, i.e. dielectric/ferroelectric responses. The supramolecular crystal is nonferroelectric and shows inconspicuous dielectric behavior when trans-1,2-cyclohexanediol is included, while a ferroelectric system is achieved when the host interacts with cis-1,2-cyclohexanediol. Moreover, the ferroelectric–paraelectric phase transition involved in cis-1,2-cyclohexanediol occurs together with an interesting chair-boat conformation change, as well as an order–disorder transition. As far as we know, this is the first discovery showing that dielectric/ferroelectric signal responses can be used to distinguish cis–trans isomers in the field of ferroelectric materials. This finding enriches studies of the molecular ferroelectric family and might provide inspiration for smart device design.