Synthesis, characterization and nonlinear optical studies of novel blue-light emitting room temperature truxene discotic liquid crystals

Abstract

A new series of discotic liquid crystals based on a truxene core has been synthesized to study the structure–property relationship in view of the self-assembling property and their linear and nonlinear optical properties. All these branched alkyl chain truxene derivatives show a mesogenic property in a columnar hexagonal fashion at room temperature which is studied by a combination of different techniques. The newly synthesized truxene discotic 7a possesses a clearing temperature of 117 °C, one of the lowest clearing temperatures known in truxene discotic liquid crystals. We have discovered that the introduction of branching near to the core even in a small alkyl chain drastically reduces the isotropic temperature. Due to their C₃ symmetry and their large first hyperpolarizability, these truxene derivatives show long-lived emissions in the solution state at room temperature. We also report large effective three-photon absorption in these materials under nanosecond laser pulse excitation at 532 nm, which makes them suitable candidates for optical limiting applications.