The synthesis and characterization of 6-hydroxymethylpyridine-2-carboxaldehyde (2-methyl-pyrimidine-4,6-diyl)bis(1-methylhydrazone) (1) is reported. Ligand 1 was designed as a ditopic pyrimidine hydrazone molecular strand with hydroxymethyl groups attached to the terminal pyridine rings. Coordination of 1 with Cu(ClO4)(2)center dot 6H(2)O or Cu(SO3CF3)(2)center dot 4H(2)O in a 1:2 molar ratio resulted in the dinuclear Cu(II) complexes [Cu(2)1(CH3CN)(4)](ClO4)(4)center dot CH3CN (4) and [Cu(2)1(SO3CF3)(2)(CH3CN)(2)](SO3CF3)(2)center dot CH3CN (5). X-ray crystallography and H-1 NMR NOESY experiments showed that 1 adopted a horseshoe shape with both pyrimidine hydrazone (pym-hyz) bonds in a transoid conformation, while 4 and 5 were linear in shape, with both pym-hyz bonds in a cisoid conformation. Coordination of 1 with Cu(ClO4)(2)center dot 6H(2)O or Cu(SO3CF3)(2)center dot 4H(2)O in a 1:1 molar ratio resulted in three different bent complexes, [Cu(1H)(ClO4)(2)](ClO4) (6), [Cu(1H)(CH3CN)](ClO4)(3)center dot 0.5H(2)O (7), and [Cu1(SO3CF3)](2)(SO3CF3)(2)center dot CH3CN (8), where the pym-hyz bond of the occupied coordination site adopted a cisoid conformation, while the pym -hyz bond of the unoccupied site retained a transoid conformation. Both 6 and 7 showed protonation of the pyridine nitrogen donor in the empty coordination site; complex 8, however, was not protonated. A variety of Cu(II) coordination geometries were seen in structures 4 to 8, including distorted octahedral, trigonal bipyramidal, and square pyramidal geometries. Coordination of the hydroxymethyl arm in the mononuclear Cu(II) complexes 6, 7, and 8 appeared to inhibit the formation of a [2 x 2] grid by blocking further access to the Cu(II) coordination sphere. In addition, the terminal hydroxymethyl groups contributed to the supramolecular structures of the complexes through coordination to the Cu(II) ions and hydrogen bonding.