Synthesis, structure and optoelectronic properties of hybrid iodobismuthate & iodoantimonate semiconducting materials.

The syntheses and structures of five iodobismuthate and nine iodoantimonate hybrid materials are presented. The 1,3-dimethyl-2-oxo-2,3-dihydropyrimidinium cation has been used to template the isostructural, one-dimensional [CHNO][SbI] (I) and [CHNO][BiI] (II), while 4-methylmorpholinium templates the compounds, [CHNO][SbI] (III) and [CHNO][BiI] (IV), both containing isolated iodopnictogenide cluster anions. Five iodoantimonate compounds, templated by piperazinium cation derivatives, have been synthesised; [CHN][SbI]·4HO (V), [CHN][SbI]·3HO (VI), two polymorphs of [CHN][SbI]·2HO (VII and VIII) and [CHN][SbI]·HO (IX), mainly adopting structures closely related to previously published 1D iodobismuthate hybrid materials. 1-Ethyl-2-methylbenzimidazolium cations, formed in situ in the reaction medium, template the isostructural 1D structures of [CHN][SbI] (X) and [CHN][BiI] (XI). 1,4-Diazabicyclo[2.2.2]octandiium (DABCOH) di-cations are shown to template a hydrated iodoantimonate structure [CHN][SbI]·2HO (XII) containing [SbI] complex anions and a mixed phase of two iodobismuthate materials; one phase contains, uniquely, a mixture of the complex anions [BiI] and [BiI] in the form [CHN][BiI][BiI]·(HO) (XIII), and the second, [CHN][BiI]·2HO (XIV), contains discrete [BiI] clusters. The stability and thermal decomposition routes of these phases have been determined using thermogravimetric analysis. UV-vis spectroscopy has been used to determine band gap energy estimates which are related, for a range of iodobismuthate and iodoantimonate materials, to their structural features and potential optoelectronic applications.