Au···I Coinage Bonds: Boosting Photoluminescence Efficiency and
Solid-State Molecular Motion
Abstract
Coinage bonds, a type of non-covalent interaction, occur between group
11 elements (Au, Ag and Cu) with electron donor groups. Despite
theoretical validation, empirical evidence remains limited. In this
study, an aggregation-induced emission (AIE)-active Au(I) complex,
ITCPAu, which exhibits Au···I coinage bonds, was revealed based
on the single-crystal X-ray diffraction and theoretical calculations.
Further examination of the luminescence properties of the ITCPAu
revealed multi-switchable behavior, including mechanochromism and
thermochromism. Nearly pure white-light emission was achieved with
Commission Internationale de L’Eclairage (CIE) 1931 chromaticity
coordinates of (0.30, 0.31) by grinding the green-emissive ITCPAu
monomer crystals. Moreover, visualization and manipulation of
solid-state molecular motion (SSMM) in the yellow-emissive ITCPAu dimer
crystals, driven by the robust Au···I coinage bonds, were revealed
through a combination of crystal engineering and luminescent properties.
Furthermore, to support the robust Au···I coinage bonds, a versatile
carrier for small solvent molecules in crystal lattices was developed
for uptake and release. Our findings provide experimental and
theoretical evidence for Au···I coinage bonds, highlighting their
ability to boost photoluminescence quantum yield (PLQY) and trigger
SSMM, emphasizing their potential in developing smart materials with
stimuli-responsive properties.