The first in situ organosulfonate-templated 3-fold interpenetrating framework built from rare tetrahedral [Cu4(μ4-SO4)] SBUs

Abstract

An interpenetrating framework, [Cu₄(SO₄)(4,4-bipy)₄]_n·2n(C₆H₅SO₄) [4,4′-bipyridine = 4,4′-bipy], has been successfully synthesized viahydrothermal reaction, in which the in situ generated p-hydroxybenzenesulfonate as guests are encapsulated within the channels. The tetrahedral [Cu₄(μ₄-SO₄)] SBUs, reported for the first time in 3D architectures, are linked by parallel double 4,4′-bipys to generate a diamondoid network formed of large adamantanoid cages which causes the 3-fold interpenetration of the networks by self-clathration. Furthermore, the existence of strong π⋯π interactions between adjacent 4,4′-bipys stabilizes the interpenetrating framework. The binding energies of the Cu 2p_3/2 level in the XPS spectrum are typical for a Cu(I) oxidation state. For the O1s, the XPS spectrum could be deconvoluted into three peaks corresponding to the three kinds of O atoms with different chemical environments. This work provides a method for constructing in situ organosulfonate-templated interpenetrating metal–organic frameworks.