The synthesis and full characterization of 3,5-diamino-N-(1-oxo-3-phenyl-1-(phenylamino)propan-2-yl)benzamide (5), as a new diamine monomer containing l-phenylalanine fractions in the structure of pendant group is presented. The stated diamine is employed as a key monomer for the in situ sol-gel fabrication of polyimide/titania nano hybrid thin films containing different titania contents. It is shown that titania particles are created in the size range of 20-80 nm, well-dispersed and enjoy the favorable spherical shapes supposing the constructive organic-inorganic interactions. The superior thermal stabilities of resulted nanocomposite films are confirmed using thermal analysis techniques. Moreover, the UV-Vis spectroscopy has shown the growing up in blocking efficiency along with the increase in titania contents. Predictably, the produced titania nanoparticles have amorphous structures.