A series of reaction-controlled coordination polymers constructed from bis(imidazole) and tetrafluoroterephthalic acid ligands: syntheses, structural diversities, properties

Abstract

Seven new mixed–ligand coordination polymers, {[Co_0.5(bib)_0.5(tftpa)_0.5]·0.5H₂O}_n (1), [Cd₂(bib)(tftpa)₂]_n (2), [Ni_0.5(bib)_0.5(tftpa)_0.5]_n (3), {[Co_0.5(tftpa)(H₂O)]·0.5bib·EtOH}_n (4), {[Cd_0.5(tftpa)(H₂O)]·0.5bib·EtOH}_n (5), [Cd₃(bib)₃(tftpa)₃(MeOH)₃]_n (6), and [Cd(bib)(tftpa)(MeOH)]_n (7) (bib = 1,4-bis(2-methylimidazol-1-yl)butane, H₂tftpa = tetrafluoroterephthalic acid) have been synthesized under different reaction conditions and characterized by elemental analysis, IR, PXRD, single crystal X-ray diffraction analysis and thermogravimetric analysis. Complex 1 exhibits an unusual [2 + 2] interpenetrating diamond framework belonging to class IIIa with the point symbol 6⁶. Complex 2 reveals a (3,4)-connected 3D framework with a unique double-stranded helical chain based on Cd–O–Cd and Cd–(COO)–Cd. Complex 3 presents a 4-fold interpenetrating 3D diamond framework belonging to class Ia with the point symbol 6⁶. Complexes 4 and 5 display a 3D supramolecular architecture built on 2D stacked layers through hydrogen bonding and π–π interactions. Complex 6 also shows a 3D 4-fold interpenetrating diamond framework belonging to class Ia with the point symbol 6⁶. Complex 7 features a 2D + 2D → 2D parallel polycatenated framework with the point symbol 4⁴·6². The structural diversity of complexes 1–7 illustrate that a subtle change can have a marked effect on the crystal architectures. Moreover, the magnetic properties of complexes 1, 3, and 4, and the solid-state photoluminescence results for complexes 2, and 5–7 were also studied.