The optical absorption and photoluminescence spectra of banana-shaped molecules 1,3-phenylene bis(4-methoxybenzylideneamine) have been investigated with an ultraviolet-visible spectrometers and a spectrofluorometer, respectively. The optical characterizations indicate that the banana-shaped molecules exhibit strong absorptions in a broad range of 260-370 nm and that they can give off strong purple photoluminescence when excited by ultraviolet photons. Using Hückel tight-binding program, we have calculated the electronic structures of the banana-shaped molecules. In light of the calculated electronic structures, the origin of the purple photoluminescence is discussed, and our results have demonstrated that not only the lowest unoccupied molecular orbital and the highest occupied molecular orbital but also the localized energy levels of the lone pairs are responsible for the recorded purple photoluminescence.