Synthesis, spectroscopic and thermal studies on solid charge-transfer molecular complexes formed in the reaction of 1-(2-aminoethyl)piperidine with π- and σ-acceptors

The solid charge-transfer molecular complexes formed in the reaction of the electron donor 1-(2-aminoethyl) piperidine (AEP) with the σ-acceptor iodine and π-acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD)were studied in chloroform at 25 0C. These were investigated through electronic spectra, infrared spectra, thermal and elemental analysis. The obtained results showed that the formed solid CT-complexes have the formulas [ ( AEP ) I ] + I 3 - , [(AEP)(DDQ)2], [(AEP)(TCNQ)2] and [(AEP)(TBCHD)] in full agreement with the known reaction stoichiometries in solution as well as the elemental measurements. The formation constant KCT (L mol−1), the molar extinction coefficient εCT (L mol−1 cm−1), the free energy change ΔG° (cal mol−1), the charge transfer energy ECT, and the ionization potential Ip were calculated for the CT-complexes [ ( AEP ) I ] + I 3 - , [(AEP)(DDQ)2], [(AEP)(TCNQ)2] and [(AEP)(TBCHD)].