We have synthesized five novel phthaloperinone dyes via a condensation reaction to be applied as yellow colorants for liquid crystal display(LCD) color filters. The reaction between 1,8-naphthalic anhydride(1a), 4-chloro-1,8-naphthalic anhydride(1b), 4-bromo-1,8-naphthalic anhydride(1c), 3-nitro-1,8-naphthalic anhydride(1d), 4-nitro- 1,8-naphthalic anhydride(1e) and 1,2-diaminoanthraquinone(2) proceeded readily giving a product in 72-88% yields. The synthesized dyes were characterized by Uv-Vis, mass spectrometry and elemental analysis. The spectral properties and thermal stability of the dyes were examined. The dyes absorb at around 400-450nm. All five dyes showed satisfactory thermal stability: the dyes retain 99-100% of its original weight at 300℃, 98- 100% at 350℃, 92-98% at 400℃, and 84-92% at 450℃. We have quantitatively evaluated the reaction mechanism and reactivity of dye molecules by means of Pariser- Parr-Pople Molecular Orbital Method(PPP-MO).