Photoconductive bent-core liquid crystalline radicals with a paramagnetic polar switchable phase

Abstract

A series of self-organizing bent-core derivatives 1[12,n], containing a highly π-delocalized stable radical as the central angular structural element, is described. The planarity of the open-shell core permits efficient π–π stacking, which results in the formation of B2 and soft crystalline phases above 100 °C. Optical, XRD and dielectric analyses of 1[12,12] indicate that the ground state of the observed B2 phase is polar antiferroelectric of type SmC_AP_A exhibiting tristable electro-optical switching. SQUID and EPR measurements revealed strong antiferromagnetic spin–spin exchange interactions below the isotropic phase, which have been estimated at θ = −46 cm⁻¹ with the Curie–Weiss law. Transient photoconductivity was observed in the B2 phase with a hole carrier mobility μ_h of 1.4 × 10⁻⁴ cm² V⁻¹ s⁻¹.