Four binuclear coordination polymers with a 63 net and self-assembly of 2D 63 topology into different supramolecular networks using unit–unit H-bonds

Abstract

In this work, crystal engineering is focused on the self-assembly of 2D 6³ topology into different supramolecular networks using unit–unit H-bonds. Four related coordination polymers, [Zn₂(teaH₂)(ndc)_1.5]·MeOH (1), [Co₂(teaH₂)(ndc)_1.5]·MeOH (2), [Zn₂(deaH)(ndc)_1.5]·MeOH (3) and [Co₂(teaH₂)(btb)]·3EtOH (4) where ndc²⁻ = 2,6-naphthalenedicarboxylate, btb³⁻ = benzene-1,3,5-tribenzoate, teaH₃ = triethanolamine, and deaH₂ = diethanolamine, contain a well-known 6³ subnet and the binuclear units. Furthermore, their 6³ nets present different hexagonal windows (chair- or ship-shaped) and diversified layer arrays (ABAB or ABCABC sequence). The 6³ subnet and symmetry-related unit–unit H-bonds as supramolecular synthons can build up different supramolecular networks. Compounds 1 and 2 show a distorted diamond supramolecular network due to formation of a square-pyramidal node. Because the formation of a seesaw-shaped node, compound 3 features a general diamond supramolecular network with 3-fold interpenetration. Compound 4 exhibits a binodal supramolecular framework in that H-bonding interactions occur between three binuclear units. In addition, the diversified layer array has endowed compound 4 with a large 1D channel, which can be characterized by standard N₂ adsorptions. Compound 4 has a type I adsorption isotherm with an appreciable adsorption of 45.04 cm³ g⁻¹ at 0.40 P/P₀, whereas 1–3 do not exhibit appreciable N₂ uptake.