Synthesis, characterization and spectroscopic structural studies of charge-transfer complexes of 1,4,8,11-tetraazacyclotetradecane-5,7-dione with iodine, TCNE and DDQ

Three novel aqueous and solid charge-transfer complexes are synthesized by the reaction of the polynitrogen cyclic n-donor 1,4,8,11-tetraazacyclotetradecane-5,7-dione (TACTDD) with the σ-acceptor iodine, the aliphatic π-acceptor tetracyanoethylene (TCNE) as well as with the aromatic π-acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) using chloroform as the medium solvent. Photometric titration measurements of the CT-solution complexes confirm the donor to acceptor ratios are 1:2 for TACTDD–I2 and TACTDD–TCNE reactions while is 1:1 for the reaction TACTDD–DDQ. These reaction stoichiometries are supported by the elemental, thermal and infrared measurements for the formed CT-solids. Accordingly, the reaction products are formulated as [(TACTDD) I]⋅I3, [(TACTDD)(TCNE)2] and [(TACTDD)(DDQ)]. The effect of the substituents, electron donating or withdrawing groups in the donor and acceptors compositions on their CT-interactions is discussed.