Novel optically active polyesters (PE)s by step-growth polymerization of a chiral diacid containing naphthalimidyl and flexible chiral groups with different diols via direct polyesterification reaction with tosyl chloride/pyridine/dimethylformamide system as condensing agent were prepared. The resulting PEs were characterized using FT-IR, H-1 NMR, UV-vis spectroscopy, fluorimetry, and elemental analysis. Fluorescence properties of the PE3h as a representative one were examined in several polar aprotic solvents which reveal that this polymer has photoactive properties. Furthermore, thermal properties of these polymers were investigated using thermogravimetric and differential thermogravimetric analyses. The glass-transition temperatures of PE3b and PE3f were recorded between 264 and 220 A degrees C by differential scanning calorimetry, and the 10% weight loss temperatures were ranging from 350 A degrees C under nitrogen. The obtained macromolecules are readily soluble in many organic solvents.