Construction of 2D interwoven and 3D interpenetrated metal-organic frameworks of Zn(II) by varying N,N′-donor spacers

Four new metal-organic frameworks (MOFs) of Zn(II) ions, [Zn-2(muco) 2(azopy) 2]center dot 3DMF center dot 2H(2)O (1), [Zn(muco)(bpee)]center dot 4H(2)O (2), [Zn(muco)(3bpdh)] (3), and [Zn-4(muco) 4(4bpdh) 4]center dot 4bpdh center dot 2H(2)O (4) (where, muco = trans, trans-muconate dianion, azopy = 4,4'-bisazobipyridine, bpee = 1,2-bis(4-pyridyl) ethylene, 3bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene, and 4bpdh = 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene) have been synthesized using mixed ligand systems and characterized structurally by single-crystal X-ray diffraction. Compound 1 has a 2D network with 2-fold interwoven, (4,4)-connected, {4(4)center dot 6(2)}-sql net topology. Compounds 2 and 3 have 3D diamondoid (dia) structures with interesting 5-fold and 3-fold interpenetrated nets, respectively, whereas, compound 4 has a 3D cubic (pcu, alpha-Po) structure with 2-fold interpenetrating, 6-connected, {4(12)center dot 6(3)} net topology. Topological analyses of 2 and 3 reveal 4-connected nets with 6(6) topology. In spite of the interweaving/interpenetration, compounds 1 and 2 possess rectangular channels with dimensions of 3.9 x 4.5 angstrom(2) and 4.3 x 7.0 angstrom(2), respectively. Photoluminescence studies showed the emissions of 1-4 and the thermal stabilities of the compounds were also examined.