Synthesis, Structure, and Electron Density Distribution in Crystals of K2(L-Trp)2(H2O) (HTrp = Tryptophane)

Abstract

The first salt of alkaline metal and L-tryptophane, K2(L-Trp)2(H2O) (I), is synthesized by the reaction of L-tryptophane (HTrp) with potassium hydroxide in an aqueous-alcohol solution. Compound I is characterized by IR and 1H NMR spectroscopy and X-ray diffraction (XRD) (CIF file CCDC no. 2184367). Compound I is found to have a layered structure due to the presence of the bridging water molecule and chelate-bridging anions. The quantum chemical calculations of the crystal structure (PBE, plane-wave basis set, 800 eV) is used to evaluate the strength of interactions of the potassium ion with the L-tryptophanate anion (depending on the coordination type) and the influence of the anion conformation on the strength of coordination, hydrophobic, and hydrophilic interactions.