inorganic chemistry

orange form (triplet MLCT). Further, the complex displays a
selective and fully reversible vapochromic response to MeOH,
CH 3 CN, and pyridine.
Che and coworkers( 244 ) went a step further and made use of
the vaporesponsive behavior in optoelectronic devices. Semicon-
ducting microwires of [Pt(CN-tBu) 2 (CN) 2 ] were obtained on
substrates by solvent evaporation or dip-and-pull approaches,
showing photo- and vapor-responsive conducting characteristics.
The characterization of photoresponsive transistors employing
the above-mentioned microwires revealed that the microwires
constitute ambipolar semiconducting materials (Fig. 27).
The photoinduced conducting characteristics suggest that the
assembled complex possesses stimuli-responsive features with
potential applications in semiconductor devices, such as
photodetectors. Interestingly, the exposure to different
environments can markedly affect the conductivity.
Changes in the crystal structure can be also triggered by
mechanical stimuli, as elegantly shown by Shinozaki et al.
( 243 ). The mechanochemical behavior of Pt(II) complexes bearing
cyclometallating tridentate ligands was investigated in terms of
solid-state luminescence. The yellow luminescence of the crystal-
line complex changed to orange when grinded into fine powder
(Fig. 28). A broad emission band, which was not detected for
the crystal, was observed in the red region of the electromagnetic
spectrum for the powder. The phenomenon was very similar to
the excimer formation observed in solution. The excimeric state
formation is facilitated by the mechanical grinding, and it is
described by the quantum chemical mixing of ground and excited

NN

Cl

Pt

400 500 600 700 800

Wavelength (nm)

Intensit

y

Abs

ABS

EM

FIG. 28. Mechanoresponsive Pt(II) complex described by Shinozaki
et al., which changes color and luminescence upon grinding. Reproduced
with the permission of the American Chemical Society ( 243 ).

92 CRISTIAN A. STRASSERTet al.