Data related to the pH-dependent photophysics of a class of rhenium complexes containing the hydroxypyridine ligand are presented. Data include ground-state pKa values, emission energies, and lifetimes. The complexes all have ground-state pKa values near 7.0 and exhibit a dramatic change in emission intensity near this pH. The lifetimes of these complexes, however, are constant over this pH range. A model is presented to account for the observed photophysical behavior. The pH-dependent emission properties of these species make them good candidates for luminescence-based pH probes, especially in the environmental and biomedical fields.
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