Control of the dual emission behaviour of mu-oxo-bridged Si(iv) corrole dimers by substituent bulkiness

The mu-oxo-bridged dimer of Si(iv) corrole has been recently reported to exhibit dual emissive properties depending on the solvent viscosity. Here we examined the control of the excited-state dynamics and dual emission by meso-aryl substituents. Less hindered 10-unsubstituted and 10-phenyl-5,15-bis(pentafluorophenyl)-Si(iv) corrole dimers and the more hindered 5,15-bis(pentafluorophenyl)-10-(2,4,6-trimethoxy)phenyl-Si(iv) corrole dimer were newly prepared and characterised. Interestingly, their solid-state structures are different: parallel, anti-parallel or orthogonal. In contrast, the energy-minimized structures in the excited state have been suggested to be parallel in all cases owing to the significant excimer-like stabilization. As a result, different emission behaviours and viscosity dependence were observed.