Abstract
The title compound, {(C(6)H(11)N(3)O(2))[CuI(3)]·H(2)O} (n) or (l-HisH(2))CuI(3)·H(2)O (1), is a chiral organic-inorganic compound that crystallizes in the monoclinic P2(1) space group. The asymmetric unit of 1 consists of one diprotonated l-histidinium cation {4-[(2S)-2-aza-niumyl-2-carb-oxy-eth-yl]-1H-imidazol-3-ium}, one Cu(+) cation, three iodide anions, and one co-crystallized water mol-ecule. The Cu(+) cations is four-coordinated by iodide anions forming a [CuI(4)] unit. Structural analysis of the [CuI(4)] unit using the Baur, τ(4), and τ(4)' indices reveals its slight deviation from ideal tetra-hedral geometry. Two iodide anions from each [CuI(4)] unit bridge adjacent Cu(+) centers, forming chiral left-handed helical [CuI(3)] (n) (2n-) polymeric chains. The biprotonated l-histidinium cations balance their negative charge and form N-H⋯I, O-H⋯I, and weak C-H⋯I hydrogen bonds with the [CuI(3)] (n) (2n-) chains. According to the Hirshfeld surface analysis, the main contributions to the crystal packing arise from H⋯I and H⋯O contacts, while C⋯I and N⋯I inter-actions indicate the presence of I⋯π contacts. The compound reported here represents the first example of a chiral A (2)CuX (3)-type metal halide, which shows potential for second-harmonic generation, polarized blue-light emission, and other non-linear optical applications.