New diolefinic laser dyes: 1,4-bis(β-pyrazinyl-2-vinyl)-benzene (BPVB)

Abstract

1,4-Bis(β-pyrazinyl-2-vinyl)benzene (BPVB) is an efficient blue laser dye. BPVB solutions in dimethyl sulphoxide (DMSO) of concentration ca. 10^–3 mol dm^–3 give laser emission in the range 417–498 nm (λ_max= 438 nm) upon pumping with a nitrogen laser (λ_ex= 337.1 nm). Both fluorescence and photochemical quantum yields have been evaluated in various solvents using various excitation wavelengths. The dye displays a relatively weak excimeric emission at ca. 500 nm in the more concentration solutions (ca. 10^–2 mol dm^–3) in DMSO. Excimer-like emission is also obtained from BPVB crystals at 510 nm that decreases in intensity upon irradiation ageing (λ_ex= 365 nm) owing to solid-state photopolymerization. BPVB undergoes solubilization in both cationic (cetyltrimethylammonium chloride; CTAC) and anionic (sodium dodecyl sulphate; SDS) micellar media. BPVB undergoes ground-state protonation. The hydrochloride salt of the dye has been isolated and identified by conductometric and thermoanalytical techniques.