Nonlinear Optical Properties of Several π Conjugated Bridge Groups based on Diketo-Pyrrole-Pyrrole: Study on the Length and Symmetry of N-atom Position Substituted Alkyl Chains

In this paper, three modified π-conjugated bridges, were selected to study the relationship between substituted alkyl chains and two photon absorption ability as well as intramolecular charge transfer property. The modification is on the N-atom position of Diketo-Pyrrole-Pyrrole bridges. Some nonlinear optical measurements as well as several spectra methods, were used. DPP-J0, DPP-J1 and DPP-J2 exhibit cross-section of 5.6 GM, 8.1 GM, and 6.4 GM. The results exhibit obvious relation on the length and symmetry of N-atom position substituted alkyl chains. A pump-probe measurement was operated at 800 nm. Ultrafast dynamics results exhibit slight difference on the intramolecular charge transfer of these conjugated bridge derivatives. The quantum chemical calculations results are well accorded with the nonlinear optical properties. The results obtained may provide some useful information on molecular design and optimization of new advanced materials.