Sugar-metal ion interactions: The coordination behavior of cesium ion with lactose, d-arabinose and l-arabinose

• Novel Cs complexes with lactose, d- and l-arabinose are reported.
• X-ray diffraction, IR, FIR, THz and Raman results are presented.
• New coordination structures are observed.

The novel cesium chloride–lactose complex (CsCl·C12H22O10 (Cs-Lac), cesium chloride-d-arabinose and l-arabinose complexes (CsCl·C5H10O5, Cs-D-Ara and Cs-L-Ara) have been synthesized and characterized using X-ray diffraction, FTIR, FIR, THz and Raman spectroscopies. Cs+ is 9-coordinated to two chloride ions and seven hydroxyl groups from five lactose molecules in Cs-Lac. In the structures of CsCl-d-arabinose and CsCl-l-arabinose complexes, two kinds of Cs+ ions coexist in the structures. Cs1 is 10-coordinated with two chloride ions and eight hydroxyl groups from five arabinose molecule; Cs2 is 9-coordinated to three chloride ions and six hydroxyl groups from five arabinose molecules. Two coordination modes of arabinose coexist in the structures. α-d-arabinopyranose and α-l-arabinopyranose appear in the structures of Cs-D-Ara and Cs-L-Ara complexes. FTIR and Raman results indicate variations of hydrogen bonds and the conformation of the ligands after complexation. FIR and THz spectra also confirm the formation of Cs-complexes. Crystal structure, FTIR, FIR, THz and Raman spectra provide detailed information on the structure and coordination of hydroxyl groups to metal ions in the cesium chloride–lactose, cesium chloride-D- and l-arabinose complexes.

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