Two new perylene dye, N,N'-bis-(aminododecyl)-3,4,9,10-perylenebis (dicarbo
ximide) (1) and N,N'-bis-(4-chlorophenyl)3,4,9,10-perylenebis (dicarboximid
e) have been synthesized. Because the solubility of perylene derivatives is
very low, their synthesis and purification are difficult. The imides 1 and
2 are easily prepared with high yield. Dye 2 has a lower density than the
density of air. They are highly fluorescent and very photostable dyes. With
high fluorescent quantum yield they are suggested as new convenient standa
rds for the fluorescence quantum yield measurements in 500-650 nm region. T
he report includes the electronic absorption and emission spectra, extincti
on coefficients and fluorescence quantum yields. Applications of the dyes a
re discussed.