Construction of Zn(II) microporous metal–organic frameworks based on 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate

•Three zinc MOFs based on H4EBTC with/without an auxiliary ligand are synthesized.•Zn(II) ions and carboxylates in different MOFs show different coordination modes.•The three MOFs are 3D microporous coordination polymers with intriguing topologies.•MOFs 1 and 3 exhibit good photoluminescence around the blue-violet region.

Three novel microporous zinc MOFs, [Zn3(EBTC)2]∙2(CH3)2NH2∙ 0.5DMSO∙3H2O (1), [Zn(EBTC)0.5(BPY)]∙2DMSO∙0.5DMF∙2H2O (2) and [Zn2(EBTC)(BPP)2]∙3DMSO∙2DMF∙5H2O (3) (EBTC = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate, BPY = 4,4′-bipyridine, BPP = 1,3-bi(4-pyridyl)propane), have been synthesized under solvothermal conditions. The versatile coordination modes of EBTC are the key to such diverse MOFs. The results of X-ray single diffraction analyses indicate that 3D microporous MOF 1 with fla topology possesses 2D [Zn3(EBTC)2]∞ layer built from 1D double-chain-like motif containing trinuclear [Zn3(COO)8]2 − SBUs, in which the two phenyls of EBTC are almost perpendicularly arranged. Compound 2 is a 3D layer-pillar structure with Zn(II) ions bridged by planar EBTC to generate 2D [Zn(EBTC)0.5]∞ sheet, and the 2D sheets are further pillared by rigid BPY to form a 3D porous framework with fsc topology. Complex 3 exhibits a 3D 2-fold interpenetrating framework with (4.64.8)2(42.64) topology, in which the flexible BPP links the 1D [Zn2(EBTC)]∞ ladder to form a 2D [Zn2(EBTC)(BPP)2]∞ structure with large 1D channels, which leads the flexible 2D framework to 2-fold interpenetration and forms a 3D porous network. Complexes 1 and 3 exhibit good luminescent properties around the blue-violet region.

Graphical abstractThree novel zinc microporous MOFs with intriguing topologies have been synthesized by the self-assembly of H4EBTC with/without the corresponding auxiliary ligand of BPY/BPP, where Zn(II) modulates its coordination geometry from octahedron and tetragonal pyramid (1), trigonal bipyramid (2) to tetrahedron coordination (3) geometry as the carboxylates in EBTC adopt different coordination modes to meet the coordination requirement of the MOFs' rigidity/flexibility. MOFs 1 and 3 exhibit good photoluminescence around the blue-violet region.Figure optionsDownload full-size imageDownload as PowerPoint slide