A Novel Family of Polyiodo-Bromoantimonate(III) Complexes: Cation-Driven Self-Assembly of Photoconductive Metal-Polyhalide Frameworks.

In the presence of different cations, reactions of [SbBr6 ]3- and I2 result in a new family of diverse supramolecular 1D polyiodide-bromoantimonate networks. The coordination number of Sb, as well as geometry of assembling {Ix }n- polyhalide units, can vary, resulting in unprecedented structural types. The nature of I⋅⋅⋅Br interactions was studied by DFT calculations; estimated energy values are 1.6-6.9 kcal mol-1 . Some of the compounds showed strong photoconductivity in thin films, suggesting multiple feasible applications in optoelectronics and solar energy conversion.

Halochromic coordination polymers based on a triarylmethane dye for reversible detection of acids.

Chromeazurol B (Na2HL) is a pH-sensitive (halochromic) dye based on a hydroxytriarylmethane core and two carboxylate functional groups, which makes it suitable for the synthesis of coordination polymers. Two new coordination polymers [NaZn4(H2O)3(L)3]·3THF·3H2O (1) and [Zn3(H2O)3(µ2-OH2)(µ3-OH)(HL)2(H2L)]·2THF·3H2O (2) incorporating Chromeazurol B linkers have been prepared and characterised. The structure of 1 comprises pentanuclear heterometallic {Zn4Na} nodes linked by six L3- anions to give a layered structure with a honeycomb topology. 2 crystallizes as a double-chain ribbon (ladder) structure with two types of metal node: a mononuclear Zn(ii) cation and tetranuclear {Zn(ii)}4 cluster. Chromeazurol B anions link each tetranuclear cluster to four individual Zn(ii) cations and each Zn(ii) cation with four tetranuclear clusters. Both compounds show pH-sensitivity in water solution which can be observed visually, giving the first example of a halochromic coordination polymer. The halochromic properties of 1 towards HCl vapors were systematically investigated. As-synthesized violet-grey 1 reversibly changes color from orange to pink in the presence of vapors of 2 M and 7 M HCl, respectively. The coordination of the Chromeazurol B anion at each color stage was examined by diffuse reflectance spectroscopy and FT-IR measurements. The remarkable stability of 1 to acid and the observed reversible and reproducible color changes provide a new design for multifunctional sensor materials.