COMPARISON OF SOLID-STATE AND SOLUTION PHOTOPHYSICAL PROPERTIES OF A PLATINUM(II) BIPHENYL DICARBONYL COMPLEX - A MULTIPLE-STATE EMISSION STUDY

Pt(bph)(CO)(2), where bph is the biphenyl dianion, displays multiple e mission by altering the temperature, solvent, or its state. Emission s pectra and emission quantum yields are concentration and excitation wa velength dependent. In dilute 4:1 ethanol/methanol at room temperature , a structured emission at high energy (similar to 500 nm) occurs, but in the solid state a nonstructured emission centered at (similar to 7 50 nm) is found. Between these extremes, two other emissions located a t similar to 540 and similar to 650 nm are observed. Emissions from hi gh energy to low energy are attributed to the following: tripler emiss ion centered on the bph ligand, emission from a dimer (exciplex), emis sion from an aggregate, and emission from ''stacked'' platinum(II) cry stals.