Spectral, Acid−Base, and Laser Characteristics of 1,4-Bis[β-(2-quinolyl)vinyl]benzene (BQVB)

The diolefinic dye BQVB is an efficient fluorescer with φ f values as high as 0.82 in n-heptane. The dye exhibits low values of the excited state lifetimes of ca. 0.4 ns. Both electronic absorption and fluorescence spectra are sensitive to medium acidity, and in acidic media a strong fluorescence is obtained at 500 nm. The laser activity of BQVB has been investigated. The dye solution in N,N-dimethylformamide (DMF) gives laser emission around 450 nm upon excitation by 337.1 nm nitrogen laser pulse. The excited state absorption S2 ← S1 of BQVB has been measured using laser flash photolysis, and in DMF the S2 ← S1 absorption occurs at ca. 762 nm. Energy transfer from BQVB to rhodamine 6G and to molecular oxygen has been studied. The quantum yields for the trans−cis photoisomerization (φ c) of BQVB in different organic solvents are also reported.