Synthesis and structural characterisation of a Co(II) coordination polymer incorporating a novel dicarboxy-Trögers base/bis-pyrazole mixed ligand system

A cobalt(II) coordination polymer, [Co(L1)(H2L2)]·2.5H2O, 1, has been prepared via the hydrothermal reaction of cobalt(II) chloride with the novel dicarboxy-Tröger’s base ligand 2,8-dicarboxy-6H,12H-5,11-methano-dibenzo[b,f][1,5]diazocine, H2L1, and the bis-pyrazole ligand 4,4′-methylenebis-(3,5-dimethylpyrazole), H2L2. The structure of 1 contains 2D (4,4) networks showing 2D → 3D parallel interpenetration, whereby adjacent 2D sheets interlock through the apertures defined by the cleft-like Tröger’s base ligand, to realise an overall 3D entanglement. The interlocking also forms one-dimensional solvent filled channels which are easily disturbed on drying resulting in framework collapse. The crystal structure of H2L1 is also reported, and represents a rare example of homochiral hydrogen bonded [6,4] dia networks interpenetrated by their enantiomeric partner frameworks.

Graphical abstractA cobalt(II) coordination polymer incorporating a novel dicarboxy-Tröger’s base ligand and the bis-pyrazole ligand are reported. The structure contains 2D (4,4) networks showing 2D → 3D parallel interpenetration, whereby adjacent 2D sheets interlock through the apertures defined by the cleft-like Tröger’s base ligand, to realise an overall 3D entanglement.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► First example of a Tröger’s base analogue as a linker in a coordination polymer. ► Structural determination of a homochiral diamondoid hydrogen bonding network. ► A 2D–3D interpenetrated Co(II) framework with polymeric bis-pyrazole helicates. ► Tröger’s base clefts encapsulating water channels.