Eight-position substitution effects on laser action of the 1,3,5,7-tetramethyl-2,6-diethyl pyrromethene-BF₂ complexes

We measured laser-action properties of some novel eight-position substituted 1,3,5,7-tetramethyl-2,6-diethyl pyrromethene-BF₂ complexes in a Littman-type cavity pumped by the second harmonic of a Q-switched Nd:YAG laser. The substitution effects were investigated by comparing the spectroscopic and laser-action properties of various eight-position substituted complexes, such as absorption, excitation, and fluorescence emission, and triplet-triplet absorption spectra, dye-laser wavelength-tuning spectra, and output-pulse energy versus the pump-laser energy. The results showed that 1,3,5,7-tetramethyl-2,6-diethyl pyrromethene-BF ₂ complexes with phenyl, p-methoxyphenyl, and p-fluorophenyl substituted at the eight-position outperformed the commercially available benchmark laser dye Rhodamine 6G (Rh6G) in fluorescence quantum yields, laser efficiency, and laser wavelength-tuning range.