Dependence of the intramolecular charge transfer on molecular structure in triazole bridge-linked optical materials

Four novel triazole bridge-linked fluorene derivatives with different terminal push/pull substituted groups were designed and controlledly synthesized via click chemistry based on Huisgen 1,3-dipolar cycloaddition reaction in high yields. Their structures were characterized and evaluated by FTIR, 1H NMR, 13C NMR, MS and elemental analyses, respectively. The results show that these triazole bridge-linked fluorene optical materials are almost prepared quantificationally by click chemistry. The intramolecular charge transfer (ICT) in these triazole bridge-linked fluorene optical materials was investigated by molecular emission and absorption spectra, and further confirmed by cyclic voltammetry (CV) technology and theoretical simulation calculation. It is found that the intramolecular charge transfer is significantly affected by molecular structure. ICT emission, ICT/locally excited (LE) mixture emission and LE emission were achieved by changing the terminal group in triazole bridged conjugates.

► Four novel triazole bridged fluorene derivatives with different push/pull substituents were synthesized via Click Chemistry.
► The influences of triazole unit on molecular structure and intramolecular charge transfer were discussed in detail.
► ICT, ICT/LE and LE emission were achieved by adjusting the structure of terminal group in triazole bridged conjugates.
► Excite-state TICT, partial excite-state ICT and ground state CT absorption were observed in T1, T2/T3 and T4, respectively.