Spectroscopic and structure investigation of the molecular complexes of tris(2-aminoethyl)amine with π-acceptors

Abstract

The intermolecular charge transfer CT-complexes of tris(2-aminoethyl)amine (TREN) with different π-acceptors such as picric acid (PIC), o-chloranil (CHL) and tetracyanoquinolines (TCNQ) were investigated in both solid and liquid phase. Spectroscopic techniques, such as FT-IR, 1H NMR, 13C NMR, and UV–vis, were used to characterize the molecular complexes. Spectral data, for example, formation constants, molar extinction coefficient, standard free energy, and ionization potentials for the complexes were calculated for the 1:1 molecular CT-complexes. Exploring the single crystal of TREN/PIC, grown by slow evaporation technique from methanol solution at room temperature, shows that CT-complex stabilized by two noncovalent interactions, namely, hydrogen bond and dipole–dipole interactions. In addition, the structure of tris(2-aminoethyl)amine and CHL and TCNQ complexes were investigated by DFT calculations at B3LYP/6-311++G(d,p) level of theory.