Optically dilute solutions of concentrations on the order of 10 -5 or 10 -6 M of the complexes were prepared in spectroscopic or HPLC grade solvents for absorption and emission analysis. Absorption spectra were recorded at room temperature on a Shimadzu UV-2600 double beam spectrophotometer a 1 cm quartz cuvette. For emission studies, degassed solutions were prepared via three freeze-pump-thaw cycles and spectra were taken using home-made Schlenk quartz cuvette. An Edinburgh Instruments FS5 spectrofluorometer equipped with a 150 W ozone-free Xenon lamp was used to collect steady-state emission spectra. (λexc =343 nm) An EPL-UV picosecond pulsed diode laser (Edinburgh Instruments, EPL-375, λexc = 375 nm) was used to collect time-resolved PL decays. Time-resolved PL measurements of solutions were carried out using the time-correlated single-photon counting (TCSPC) or multi-channel scaling (MCS) technique. An open 150 mL liquid nitrogen EPR Dewar was used for emission measurements at 77 K in butyronitrile. Photoluminescence quantum yields for solutions were determined using the optically dilute method in which four sample solutions with absorbances between 0.2 to 0.02 at 350 nm were used. The Beer-Lambert law was found to remain linear at the concentrations of the solutions. For each sample, linearity between absorption and emission intensity was verified through linear regression analysis with the Pearson regression factor (R 2 ) for the linear fit of the data set surpassing 0.9. Individual relative quantum yield values were calculated for each solution and the values reported represent the slope obtained from the linear fit of these results. The quantum yield of the sample, FPL, can be determined by the equation