The isomeric effect on the D-π-π-A prototype fluorescent material: synthesis, photophysical property, and computation

Two novel organic fluorescent isomers with D-π-π-A prototype structure, namely, ( E )-2-[3-([1,1'-biphenyl]-4-yl)-1-(6-methoxynaphthalen-2-yl)allylidene]malononitrile and ( E )-2-[1-([1,1'-biphenyl]-4-yl)-3-(6-methoxynaphthalen-2-yl)allylidene]malononitrile, were synthesized. Due to the exchange of naphthalene and biphenyl moieties on each side of conjugated bridge (C = C(CN) 2 )-conjugated bridge (C = C) group, two compounds are organic fluorescent isomers, and display different molecular stacking mode and photophysical property. Molecules of ( E )-2-[3-([1,1'-biphenyl]-4-yl)-1-(6-methoxynaphthalen-2-yl)allylidene]malononitrile are packed with H-aggregation, while ( E )-2-[1-([1,1'-biphenyl]-4-yl)-3-(6-methoxynaphthalen-2-yl)allylidene]malononitrile has a J-aggregation. Both of two compounds show solvatochromism and tunable aggregation-induced enhanced emission property. Graphic abstract