Solids with rhombic channels: Syntheses and crystal structures of [Cu-3(NTA)(2)(4,4 '-bpy)(2)(H2O)(2)]center dot 9H(2)O and [{Cu(4,4 '-bpy)(H2O)(4)}{Cu-2(NTA)(2)(4,4 '-bpy)}]center dot 7H(2)O (NTA = nitrilotriacetate, 4,4 '-bpy = 4,4 '-bipyridine)