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]⁺I3-, [(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 K_CT (L mol^-1), the molar extinction coefficient *_CT (L mol^-1 cm ^-1), the free energy change ΔG° (cal mol^-1), the charge transfer energy E_CT, and the ionization potential Ip were calculated for the CT-complexes [(AEP)I]⁺I3-, [(AEP)(DDQ) ₂], [(AEP)(TCNQ)₂] and [(AEP)(TBCHD)].