A new building block, bis(thiophene vinyl)-pyrimidine, for constructing excellent two-photon absorption materials: synthesis, crystal structure and properties

Two new molecules (Py1 and Py2) of D-pi-A-pi-D motif, where the -pi-A-pi-moiety is bis(thiophene vinyl)-pyrimidine as a building block, have been designed and synthesized via the Knoevenagel and Suzuki coupling reactions. The X-ray single crystal structure analysis of Py1 showed good coplanarity in the whole building block. Their two-photon absorption (2PA) properties were measured by two-photon induced fluorescence techniques with a mode-locked Ti: sapphire pulsed laser in the range of 700-940 nm. Both Py1 and Py2 exhibited large cross-section values of 1702 and 1879 GM, respectively, no matter whether the peripheral donor is weak or strong. The results demonstrate that bis(thiophene vinyl)-pyrimidine is a new building block for constructing molecules with effective 2PA.