New directions in tin sulfide materials chemistry

Tin sulfide-based materials can exist in many forms, ranging from discrete molecular species, to 1D chains, 2D dense and porous sheets and 3D open frameworks. The local coordination geometry around a tin center may vary from trigonal pyramidal, to tetrahedral, trigonal bipyramidal and octahedral, and around sulfur from terminal, v-shaped to trigonal pyramidal. The oxidation state may take +2 and +4 for tin and –2, –1, 0 for sulfur. The tin sulfide chemistry is further enriched by the catenation ability of sulfur. In addition, other elements (metal and non-metal) can be incorporated into the tin sulfide structures to yield ternary and quaternary materials. More importantly, using the recent developed ‘soft chemistry’ synthetic approach, various novel porous tin (poly)sulfide materials have emerged that display interesting optical, electrical and adsorption properties. Representative tin sulfide materials will be presented and discussed in this review to demonstrate the development of tin sulfide chemistry in the last three decades.