A high Z′ structure of an organic salt with unusually high phase stability, nanoindentation, and mechano and vapo-fluorochromism

Abstract

Understanding the molecular packing is pivotal to understand the process of crystal growth and the establishment of the structure–property relationship. We report a two-component organic crystal 1, with extraordinarily high Z = 64, Z′′ = 32 and Z′ = 16. Low Z′ polymorphs of the reported structure remain elusive and crystallization and recrystallization from numerous solvent systems under different conditions yielded crystals with the same cell values. DSC and variable temperature powder-X-ray diffraction studies of the salt indicate the absence of any phase transition in the crystal prior to its melting point. The crystal exhibits unusually high thermal stability and does not undergo any phase transformation before melting, as validated by variable temperature powder X-ray diffraction and thermal studies. Quantification of the nanomechanical properties provides further structural insights. Interestingly, 1 exhibits rare dual stimuli-responsive behavior on grinding and exposure to base fumes.