Manipulation of the Electronic and Structural Effects on the Solid-State Emission of Multiple Linked Anthracenyl-o-Carborane Dyads

A direct boost the emission efficiency is presented based on the strategy of link multiple weak AIE-active anthracenyl-o-carborane dyad together for improving solid-state luminescence. Multiple anthracenyl-o-carborane dyad, linked with benzyl (CA1), 1,3-bismethyl-benzene (CA2), 1,3,5-trismethyl-benzene (CA3), were prepared and fully characterized, and compared their optical properties. Various types of substituent groups at the adjacent carbon atom of o-carborane can restrict vibration of Ccage–Ccage bonds and rotational motion of the o-carborane moiety and regulate the orientation of ICT from the electron-donating moiety to the o-carborane cluster. CA1, CA2 and CA3 are all AIE-active molecules. The emission efficiencies of CA1, CA2 and CA3 were 8- to 16-fold greater than that of anthracenyl-o-carborane dyad (F = 4.3%) in solid state, clearly indicating that the combination of multiple anthracenyl-o-carborane dyads should be valid for enhancing luminous efficiency. DFT calculations on the structures of excited state suggested that the ICT emission is via the twisted intramolecular charge transfer (TICT) mechanism in the multi-linked anthracenyl-o-carborane dyads.