inorganic chemistry

D. CRYSTALLINEASSEMBLIES

Eisenberget al.( 240 ) reported a Pt(II) terpyridine complex
bearing a nicotinamide moiety. The complex is brightly lumines-
cent in the solid state at room temperature exhibiting a remark-
able reversible vapochromic behavior and crystallographic
change in the presence of several volatile organic solvents
(Fig. 26). Upon exposure to methanol vapors, it shifts color from
red to orange, and a displacement to higher energy is observed in
the emission maximum with an increase in excited-state lifetime
and emission intensity. The crystal and molecular structures of
the orange and red forms, determined by single-crystal X-ray dif-
fraction on the same single crystal, were equivalent at molecular
level and only modestly different in terms of packing. In both

550

0

1.1

Normalized intensity

600 650

*

nm

700 750

Before exposure

After exposure

+N

N

2PF 6 –

+ MeOH (g)

• MeOH (g)

N N

Cl

Pt

NH 2

O

FIG. 26. Pt(II) complex displaying reversible color and luminescence
switching after exposure to MeOH vapor, as described by Eisenberg
et al. Reproduced with the permission of the American Chemical
Society ( 240 ).

90 CRISTIAN A. STRASSERTet al.