Study On Nonlinear Optical Properties Of Bis-chalcone Derivatives

With the development of nonlinear optics,the research on organic nonlinear optical materials has become increasingly important.Organic nonlinear optical materials have been widely used in many fields,such as two-photon biological imaging,light limiting,and so on.Looking for nonlinear optical materials with excellent performance has been a hot research direction.In this paper,two bis-chalcone molecules 1,4-bis[3-(2,4-dimethoxyphenyl)-2-acryloyl]benzene(C1)and 4,4'-bis[3-(2,4-bimethoxy phenyl)-2-acryloyl]biphenyl(C2)are synthesized and characterized.The frontier orbital distributions and the charge transfer properties from the ground state(S0)to the excited state(S1)of the two compounds are obtained by DFT and TD-DFT calculations.And the excited state absorption and dynamic processes of C1 and C2 are measured by the femtosecond transient absorption(TA)spectrum.In addition,the nonlinear optical response of the two compounds from 515nm to 800nm is studied through the open-aperture Z-scan experiment.Finally,the broad-band optical-limiting performance of compound C2 in the femtosecond range is measured.The results show that there is strong intramolecular charge transfer in C2 compound,and C2 has more ? electrons.The TA spectra indicate that C2 has stronger excited state absorption and longer excited state lifetime than C1.In addition,C2 has stronger nonlinear absorption in the visible range after 500nm.Its nonlinear response mechanism is two-photon absorption induced excited state absorption(TPA-ESA).These results indicate that the nonlinear properties and excited states dynamics of bischalcone derivatives can be enhanced by intramolecular charge transfer and more ? electrons.The favorable optical limiting response of C2 shows the promising value for optical limiter.