Influence of cations on optical properties of Iodobismuthates

Abstract Synthesis of Iodobismuthates and tuning their properties attracted a lots of attention due to their contribution in developing opto-electronic devices. Two 1-D polymeric iodobismuthate compounds, {[2,6-(NH2)PyH][BiI4]}n (1), {[4-NMe2PyH][BiI4]}n (2), stabilised by two different pyridinium derivatives namely 2,6 bis(amino)pyridine and 4-(N,N-dimethylamino)pyridine have been reported here. The compounds have been characterised by single crystal XRD, IR and elemental analysis. It is interesting to observe that the structurally similar compounds differ drastically in their optical properties because of slight variation in the cations. Comparison in structural features and their thermal, optical properties (band gap : 1.91 eV (1); 2.10 eV (2)) have been discussed. Thermochromism is exhibited by 1. DFT studies of compound 1 has been performed considering the crystal structure measured at two different temperature and the role of cation in tuning the optical properties of iodobismuthates has been established.