The weak charge-transfer complexations among 48 compounds, including 5 acceptor and 3 donor homologous series have been investigated by electronic spectroscopy. Both complexation and apparent noncomplexation exist in cases of interaction of homologous donors with same acceptor, homologous acceptor with same donor, or homologous donors with homologous acceptors. Generally, the higher homologs exhibit apparent noncomplexation; in some cases, both the higher and the lower homologs exhibit apparent noncomplexation. This phenomenon was discussed in terms of of FMO energies.

Key words: CHARGE TRANSFER COMPLEX, ELECTRON ACCEPTOR, ELECTRON SPECTROSCOPY, COMPLEXATION, FRONTIER ORBITAL THEORY, MOLECULAR ORBITAL METHOD, ELECTRON DONOR