128
5 Mechanical-Stimulation-Triggered and Solvent-Vapor-Induced …
SCSC transitions [1d–g, 5]. Ito H. et al. have recently reported the first example for
two “molecular domino” phenomena using arylgold(I) isocyanide complexes 1 [5a]
and 2 [5b]: upon gentle mechanical pricking on the surface of thermally metastable
polymorph crystals of 1 and 2, the entire crystals spontaneously transform into
their thermally stable polymorphs (Fig. 5.1a) [5]. These phase changes proceeded
in an SCSC manner under a concomitant drastic change of the emission color that
arises from changes in the crystal structure. A comparison of the crystal structures
of the mother and daughter phases revealed changes in the aurophilic interactions
and dihedral angles between the aryl groups, both of which are key features that
determine the luminescence properties of these compounds [5]. These mechanicalstimulation-triggered SCSC phase transitions are only able to drive the transformation of a metastable polymorph into a thermodynamically more stable polymorph
5. In these cases, reversed phase changes were not observed, and recrystallization
Fig. 5.1 a Molecular structure of the aryl gold(I) isocyanide complexes of 1, 2, and 3. b Schematic
representation of the present work
5 Mechanical-Stimulation-Triggered and Solvent-Vapor-Induced …
SCSC transitions [1d–g, 5]. Ito H. et al. have recently reported the first example for
two “molecular domino” phenomena using arylgold(I) isocyanide complexes 1 [5a]
and 2 [5b]: upon gentle mechanical pricking on the surface of thermally metastable
polymorph crystals of 1 and 2, the entire crystals spontaneously transform into
their thermally stable polymorphs (Fig. 5.1a) [5]. These phase changes proceeded
in an SCSC manner under a concomitant drastic change of the emission color that
arises from changes in the crystal structure. A comparison of the crystal structures
of the mother and daughter phases revealed changes in the aurophilic interactions
and dihedral angles between the aryl groups, both of which are key features that
determine the luminescence properties of these compounds [5]. These mechanicalstimulation-triggered SCSC phase transitions are only able to drive the transformation of a metastable polymorph into a thermodynamically more stable polymorph
5. In these cases, reversed phase changes were not observed, and recrystallization
Fig. 5.1 a Molecular structure of the aryl gold(I) isocyanide complexes of 1, 2, and 3. b Schematic
representation of the present work