Synthesis and structure investigation of a novel 3-dimensional potassium supermolecular compound based on 2,4-dinitro resorcinol

A novel 3-dimensional potassium supermolecular compound [K(HDNR)(H ₂DNR)(H₂O)]_n (H₂DNR = 2,4-dinitro resorcinol) was synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure investigated by X-ray single crystal diffraction shows that [K(HDNR)(H₂DNR)(H₂O)]_n crystallizes with a monoclinic unit cell in the space group P2(1)/c with unit cell dimensions of a=17.648(5) Å, b=12.527(3) Å, c= 7.735(2) Å, β=94.33(2)°, V=1705.00(73) ų, Z=4. The structure was refined to the final R=0.0670 and wR= 0.0722 for 2022 observed reflections with I>,2σ(?). In the compound, potassium cation is assembled into one-dimensional chains along c-axis through oxygen atoms from water molecules, and the chains were connected by the bridged HDNR^- anions to form a two-dimensional net structure. The two-dimensional nets constructed a three-dimensional supramolecular architecture via intermolecular hydrogen bonds and N - O···π interaction. Density functional theory (DFT) B3LYP was employed to optimize the structure and calculate energies for three tautomers of HDNR^- univalent anion. Three stable tautomers were located. It was found that the structure (I) with O(1) losing hydrogen atom is more stable than the structure (II) also with O(1) losing hydrogen atom and the structure (III) with O(4) losing hydrogen atom.