Vibrational characteristics of triethylamine–Mn(II) complex self-assembled with the formation of hydrophobic core in comparison with those of diethylamine–Mn(II) complex

Properties of diethylamine–MnCl2 and triethylamine–MnCl2 complexes formed in aqueous solutions have been investigated by electronic absorption and infrared spectroscopy, and by simultaneous atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM). Formation of compact hydrophobic core is found by AFM/SNOM for the TEA–MnCl2 complex in contrast with DEA–MnCl2 one. In the assemblies of both complexes Mn(II) oxidation to Mn(III) was monitored by the appearance of bands of MnOH stretching and bending vibrations in the IR spectra near 665 and 750 cm−1, respectively. In assemblies of DEA–MnCl2 complex Mn(II) has been oxidized by O2. While in the presence of O2 Mn(II) was retained in the non-oxidized state in the TEA–MnCl2 complex self-organized with the formation of the hydrophobic core. Vibrational characteristics of these complexes are considered depending on different states of Mn and interaction with dioxygen. A broadened signal with the width of 80 mT found by ESR spectroscopy supports the assembled state of Mn(II) in the complex with TEA in the compact hydrophobic core.