UV-Vis, IR spectra, mass spectrometry and thermal studies of charge transfer complexes formed in the reaction of 1, 4, 8, 11-tetraazacyclotetradecane with π-electron acceptors

The solid charge-transfer (CT) molecular complexes formed in the reaction of the electron donor 1,4,8,11-tetraazacyclotetradecane (TACTD) with the pi-electron acceptors 2,4,6-tetrafluoro-1,4-benzoquinone (TFQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) have been investigated spectrophotometrically in chloroform at 25 degrees C. These were characterized through electronic and infrared spectra as well as elemental and thermal analysis. The obtained results showed that the formed solid CT-complexes have the formulas [(TACTD)(TFQ)(2)] and RTACTD)(DDQ)(2)] and RTACTD)(TBCHD)(2)] in full agreement with the known reaction stoichiometry in solution as well as the elemental measurements. The formation constant k(CT), molar extinction coefficient epsilon(CT), free energy change Delta G degrees, CT energy E-CT and the ionization potential Ip have been calculated for these CT-complexes. (C) 2019 Elsevier B.V. All rights reserved.