Synthesis, optoelectronic properties and third-order nonlinear optical behaviors of the functionalized acene derivatives

In this work, a novel malononitrile-modified acene 2-(2,7-di-tert-butyl-9,17-diphenyl-15H-dibenzo[hi,mn]indeno[1,2-b]tetracen-15-ylidene) malononitrile (DITAM) has been synthesized and characterized. Its single crystal X-ray analysis shows that DITAM features an antiparallel configuration and has a cis-form in the packing model, which is different from its analogue 2,7-di-tert-butyl-9,17-diphenyl-15H-dibenzo[hi,mn]indeno[1,2-b]tetracene (DITA). In comparison with UV-vis absorption and fluorescence spectra in different solvents of compounds DITAM, DITAO, and DITA, molecule DITAM displays the strongest salvation, inferring that ICT occurs in the excited state. Electrochemical results combined with the theoretical calculation illustrate that the malononitrile unit can effectively lower the LUMO energy level. The third-order nonlinear optical behaviors of the as-prepared compounds were investigated in a comparative manner, where DITAM exhibited the best optical nonlinear performance.