On the causes of altered photophysics of luminescent metal complexes embedded in polymer hosts

A suite of luminescent Re(I) complexes has been prepared whose emissive properties are responsive to the probe's local environment. These complexes were embedded in a series of chemically similar polymers whose room temperature rigidity varied over a significant range. It is shown that the degree of local rigidity experienced by the embedded complexes significantly alters the observed emission in terms of both spectra and lifetime. Time resolved emission measurements show that the spectral shifts and lifetime complexity are correlated and track well the polymers' T(g) within the series. Fluorescence confocal microscopy did not show the presence of discrete domains, and thus, the environmental features responsible for the altered photophysics must be submicrometer in size.