Rational design of zinc-organic coordination polymers directed by N-donor co-ligands

A family of Zn(II) -based metal-organic coordination polymers (MOCPs) [Zn(L)(imid)(2)] (1), [Zn(L)(2,2'-bpy)] (2), [Zn(2)(L)(2)(Py)(3)] (3), [Zn(L)(DPP)]⋅DMF (4), [Zn(L)(DPEA)] (5), [Zn(2)(L)(2)(4,4'-bpy)] (6), [Zn(L)(3,4'-DPEE)]⋅DMF (7), and [Zn(3)(L)(3)(3,4'-DPEE)(2)]⋅DMF (8) (L=dithieno[3,2-b:2',3'-e]benzene-2,6-dicarboxylic acid, imid=imidazole, bpy=bipyridine, Py=pyridine, DPP=1,3-di(pyridin-4-yl)propane, DPEA=1,2-di(pyridin-4-yl)ethane, and DPEE=(E)-3,4'-(ethene-1,2-diyl)dipyridine) have been rationally designed and generated in the solvothermal reaction systems of the new conjugated thiophene derivative L, Zn(ClO(4))(2)⋅6H(2)O, and seven different aromatic N-donor co-ligands separately. These N-donor compounds were carefully selected and employed in the crystal preparation of the eight MOCPs as structure-directing co-ligands owing to their structural specialties and habitual coordination fashions. Among these MOCPs, compounds 1-3 are 1D polymers with different chain structures. Compounds 4, 7, and 8 are 2D structures, in which 4 has two sets of twofold interpenetrating layers, whereas 7 and 8 are both built from three independent sheets. Compounds 5 and 6 are 3D frameworks, in which 5 exhibits a fivefold interpenetrating diamondoid network, whereas 6 shows a typical twofold interpenetrating pillared layer structure with nanoscale channels. The photoluminescent properties of these MOCPs, including excitation, emission, and radiactive lifetime, have also been investigated to help us tentatively understand their structure-property relationships.