Synthesis and characterization of novel thiazolo[5,4-d]thiazoles as two photon absorbers (TPA)

Recently, an increasing interest in the design of NLO chromophores for two photon absorption (TPA) applications has been motivated by the vast applications of TPA phenomenon in fields such as materials science (3D data storage and microfabrication, optical power limiting), biology and medicine (fluorescence imaging, two-photon microscopy (TPM), photodynamic therapy). For in vivo imaging, two-photon processes allow finer resolution and in-depth tissue penetration, with reduced cell damage. High two-photon excited fluorescence (TPEF) quantum yields, good photostability, adequate solubility, and optimized response wavelengths are also required in fields such as fluorescence microscopy or upconversion lasing.1 Incorporation of heterocycles into pi-conjugated systems allows the fine tuning of electrooptical properties and often results in strong fluorescence, mandatory for certain TPA-based applications. Recently, we have studied the potential of push-pull systems bearing thiophene, pyrrole and benz-X-azole heterocycles with high thermal and photophysical stabilities, interesting emissive properties and second and third order optical responses.2 In this communication the results concerning the synthesis and evaluation of the TPA properties of novel heterocyclic pi-conjugated systems will be presented and discussed.Fundação para a Ciência e a Tecnologia (FCT