Molecular engineering of octupolar tris(bipyridyl) metal complexes

Metal complexes of nitrogen-heterocyclic ligands, such as bipyridines, repr esent an important class of nonlinear optical (NLO) chromophores. They are associated with low-energy intraligand charge-transfer (ILCT) and/or metal to ligand charge-transfer (MLCT) symmetry. To design excitations. These lig ands are excellent building blocks for the construction of octupolar metal complexes of D-3 tris(bipyridyl) metal complexes with enhanced optical nonl inearities, we have developed the synthesis of a series of 4,4'-dialkenyl-2 ,2'-bipyridines bearing pi -donor substituents. The influence of the metal on the linear and nonlinear optical properties has been investigated. This study shows that the NLO response can be fine-tuned by changing either the donor cup or the metal centre. (C) 2001 Elsevier Science B.V. All rights re served.