inorganic chemistry

have excited-state lifetimes of 27ms with emission quantum
efficiencies exceeding 0.5. Intermolecular organization clearly
has a significant effect on emission characteristics. Thus, the
combination of emitter and liquid crystalline properties offers
control over the nature of the emission via the molecular organi-
zation. The high-luminescence efficiency coupled with the poten-
tial to align the complexes in the liquid crystal phase promises to
yield highly dichroic emission.

C. 3D NETWORKS

Low-molecular weight organo- or hydrogelators have been
widely investigated( 260 – 265 ); the operating mechanism of gela-
tion has been identified as a supramolecular effect, where the
constituting fibers, usually of microscale lengths and nanoscale
diameters, are formed in solution predominantly by unidirec-
tional self-assembly of gelator molecules ( 266 – 269 ). The entan-
glement of many filaments gives a network that entraps the
solvent molecules within the compartments. In most cases, the
intermolecular interactions are electrostatic, hydrogen bonds
andp
pstacking and are induced by heating and cooling of the
solution and most recently by ultrasounds ( 270 ). We also have
demonstrated that gel formation in water can be induced by

OC OCnH^2 n+1

nH 2 n+1

OCnH 2 n+1

OCnH 2 n+1

O O

O O

N

N

Pt

Pt

FIG. 19. Orthoplatinated rod-like Pt(II) complexes. Reproduced with
the permission of the American Chemical Society ( 211 ).

PHOTOPHYSICS OF MOLECULAR ASSEMBLIES 81