(C 6 H 15 N 3 ) 1.3 (NH 4 ) 1.5 H 1.5 In 3 SnS 8 : a layered metal sulfide based on supertetrahedral T2 clusters with photoelectric response and ion exchange properties.

A new layered metal sulfide, namely (C 6 H 15 N 3 ) 1.3 (NH 4 ) 1.5 H 1.5 In 3 SnS 8 (1, C 6 H 15 N 3 = N -(2-aminoethyl) piperazine), has been solvothermally synthesized and characterized. Compound 1 crystallizes in the monoclinic space group C 2/ c . Its structure features a two-dimensional layer of {In 3 SnS 8 } n 3 n - with the (4,4) topology net, which is formed by interlinking supertetrahedral T2 clusters as secondary building units. Band structure calculations revealed that 1 had a band gap of 2.7 eV. The photoelectric response of 1 showed steady and reversible on/off cycles with an "on" state of 121.13 nA cm -2 . Moreover, the activation of 1 by replacing the sluggish organic cations with harder K + ions endowed the material with improved adsorption performances for Sr 2+ ions from aqueous solutions.