Synthesis, Spectral Properties, Crystal Structure and DFT Studies of 2,2′-diamino-4,4′-(propane-2,2′-diyl)-Diphenol

A bisphenol-A derivative, 2,2′-diamino-4,4′-(propane-2,2-diyl)-diphenol (3), was synthesized by nitration of bisphenol-A and then by its reduction. The title compound was characterized by elemental analysis, typical spectroscopic techniques, namely FT-IR, ¹H-NMR, and ¹³C-NMR. The structure of the compound was also determined by single crystal X-ray diffraction method. The compound crystallized in the orthorhombic system with space group P_bcn and a = 15.51106(18) Å, b = 11.6910 (10) Å, c = 7.6473 (7) Å. It is seen that the hydrogen atoms of the -OH groups are in trans-position to the NH2 groups in the crystal structure of the title compound. Moreover, it was observed in the dimeric lattice that the hydrogens of the –NH₂ groups made intramolecular and those of the –OH groups intermolecular hydrogen bonds. The geometry of the compound was optimized by the DFT method and the results were compared with the X-ray diffraction data. Frontier molecular orbitals of the title compound were calculated by using the B3LYP/6-31G(d) method. MEP analysis and Mulliken charge density, Global reactivity and thermodynamic properties were also performed.

Graphical Abstract

The single crystals of 2,2׳-diamino-4,4׳-(propane-2,2-diyl)-diphenol was obtained and by refining the structure, the –NH⋅⋅⋅O and –OH⋅⋅⋅N hydrogen bonding interactions in the crystal structure was investigated by experimentally and theoretically.