Pressure-induced phase transitions in new luminescent gold(I)-arylacetylide

Abstract

Stimuli-responsive molecular materials are highly desirable because of the wide range of their potential applications. In particular, physical properties switching opens application pathways for molecular materials as sensors or actuators. Property switching in solids can be achieved by inducing single-crystal-to-single-crystal (SCSC) phase transitions. Elucidating the mechanisms of such transformations and identifying the factors and (supra)molecular motifs which increase their probability is thus paramount to understanding property switching and materials design. Here we present a new compound, (p-methoxy-phenylacetylide)(triethylphosphine)gold(I) (ArPEt), combining the photoluminescent core of gold(I) acetylide with triethylphosphine that should provide rich conformational landscape and should thus favor SCSC phase transitions. We demonstrate its potential to undergo multiple pressure-induced SCSC transformations at ≈0.5 GPa and ≈2 GPa, the obtainable phases being dependent on the type of applied pressure-transmitting media. We describe structures of high-pressure polymorphs of ArPEt and propose mechanism ('molecular gears') of pressure-induced structural reorganizations based on very high-quality single crystal X-ray diffraction data.