Synthesis and self-assembly of tetraphenylethene and biphenyl based AIE-active triazoles

Self-assembly of fluorescent functional materials has attracted increasing interest in the fabrication of optoelectronic and biological nanodevices. Tetraphenylethene (TPE) is a typical dye molecule with aggregation-induced- emission (AIE) characteristics. Melding TPE carrying triple-bond functionality with diazide-containing biphenyl through "click" chemistry generates AIE-active luminogens [1,1′-biphenyl]-4,4′-diyl bis(6-(4-(4-(1,2,2- triphenylvinyl)phenyl)-1H-1,2,3-triazol-1-yl) hexanoate) [1(5)] and [1,1′-biphenyl]-4,4′-diyl bis(11-(4-(4-(1,2,2-triphenylvinyl)phenyl) -1H-1,2,3-triazol-1-yl) undecanoate) [1(10)] with solid state efficiencies up to unity. Slow addition of dilute THF solutions of 1(m) (m = 5, 10) into nonsolvents such as n-hexane and water yields self-assembled white wooly solids. TEM and SEM observations reveal the (helical) nanofibrous structure of the aggregates. Upon cooling from their concentrated hot solutions, 1(m) readily precipitate. Meanwhile, they can also form gels at high concentrations. Both precipitates and gels of 1(m) exhibit structures similar to those of the aggregates formed in nonsolvents. These results indicate that 1(m) can facilely self-assemble into high emission efficiency (helical) nanofibers, thus paving the way for their optoelectronic and biological applications.