One‐, Two‐ and Three‐Dimensional 3d‐4f Heterometal Complexes Constructed from Pyridine‐2,3‐dicarboxylic Acid

The reaction of pyridine-2,3-dicarboxylic acid (2,3-pydcH(2)) with CuI and Ln(2)O(3) under hydrothermal conditions generated a series of new one-, two-, and three-dimensional coordination polymers, namely, {[Cu(3)Ln(2)(2,3-pydc)(6)(H2O)(12)]center dot 12H(2)O}n [Ln = La(1), Nd(2)], {[Cu(3)Ln(2)(2,3-pydc)(6)(H2O)(8)]center dot 6H(2)O}n [Ln = Sm(3), Gd(4)], and {[Cu(3)Ln(2)(2,3-pydc)(6)(H2O)(10)]center dot 10H(2)O}n [Ln = Tb(5), Ho(6), Er(7), Yb(8), Lu(9)]. The results show that compounds 1 and 2 (type I structure) are 1-D Cu-4f rhombic lattice chains that are formed through assembly of two building block units Cu-3(pydc)(6) and Ln(H2O)(6). Compounds 3-4 (type II structure) are 2-D layers that are constructed from building block units [Cu(pydc)(2)(H2O)(2)] mu(2)-bridging adjacent 1-D rhombic lattice chains -[(Cu-2(pydc)(4))-(La(H2O)(4))]n-. Complexes 5-9 (type III structure) are also isomorphous and have the same 3-D network structures with 1-D channels along the c axis, and are formed by assembly of building block units Cu-3(pydc)(6) with Ln(H2O)(5). The progressive structural variation from the 1-D chains 1-2 to 2-D layers 3-4 and to 3-D frameworks 5-9 is attributed to the lanthanide contraction effect and to the different coordination modes of 2,3-pydc(2-). The N-2 gas adsorption and fluorescent properties of the partial complexes were also investigated.