Synthesis of the macrotricyclic ligands 8,18 dioxa-1,5,11,15-tetraaza-[13.5.2.25,11]-eicosane (L1) and 7,16 dioxa-1,4,10,13-tetraaza-[11.5.3.34,10]-octadecane (L2). Crystal structures of the copper(II) complexes, [Cu(L1)](ClO4)2 and [Cu(L2)](ClO4)2·CH3NO2