Capture of volatile iodine by newly prepared and characterized non-porous [CuI]n-based coordination polymers

Abstract

Four new non-porous CuI-coordination polymers [Cu₂(μ₃-I)₂(μ-bpb)]_n (1a), [Cu(μ₂-I)(μ-bpb)]_n (1b), [Cu₄(μ₂-I)₄(μ-bpmb)₄]_n (2), and [CuI(μ-bdb)]_n (3) (bpb = 1,4-bis(pyrazolyl)butane; bpmb = 1,4-bis[(pyrazolyl)methyl]benzene; bdb = 1,4-bis[(3,5-dimethylpyrazolyl)methyl]benzene) have been successfully prepared and their structures fully characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, PXRD and elemental analysis. Crystallographic investigation revealed that 1a, 1b, and 2 exhibit two-dimensional (2D) structures; in 1a parallel [Cu₂I₂]_n staircase motifs are cross-linked into two-dimensional sheets by bpb linkers with a fully extended conformation, while in the structures of 1b and 2 Cu₂I₂ rhomboid dimers are linked by bpb and pbmb ligands, respectively, into two-dimensional sheets with a 4⁴-sql net. Differently, compound 3 shows a one-dimensional (1D) zigzag chain structure with monomeric CuI units. All the four non-porous coordination polymers show the ability to capture volatile iodine in the gas phase. The solid-state photoluminescence properties of 1a, 1b, and 2 have also been investigated. The iodine-adsorbed samples 1a-I₂, 1b-I₂, and 2-I₂ show no fluorescence behavior.