Crystal structure of 9,9′-(4,4′-(silinane-1,1-diyl)bis(4,1-phenylene))bis(9H-carbazole) and its photophysical and electrochemical properties

The title compound 9,9′-(4,4′-(silinane-1,1-diyl)bis(4,1-phenylene))bis(9H-carbazole) (6-bisCz) has been designed and prepared to investigate its crystal structure and photophysical and electrochemical properties. 6-bisCz is crystallized in the centrosymmetric space group P−1. Interestingly, the asymmetric unit contains two molecules (Z′ = 2), and hence, the entire cell contains four units (Z = 4). The central silicon atom was arranged in pseudo-tetrahedral geometry defined by the two ipso-carbon atoms of the phenyl groups and two carbon atoms in the endocyclic hexyl ring, with average bond angles of 104.5(1)° and 108.5(1)°, respectively. UV/Vis absorption and photoluminescence spectra showed that the central silicon atom successfully disconnected electronic communication between the two peripheral phenylcarbazole units, yielding similar absorption and emission spectra to an unsubstituted carbazole monomer. The influence of the central silicon atom between the two phenylcarbazole units is also simulated by density functional theory calculations. Finally, electrochemical properties of 6-bisCz were investigated, and the analysis shows that an electropolymerized film was successfully formed during the electrochemical process.