Theoretical Study of the Hg²⁺ Recognition by 1,3-Diphenyl-Thiourea

Abstract

We have studied the electronic and structural properties responsible for the molecular recognition that the 1,3-diphenyl-thiourea ionophore (L) experiences by the Hg2+ cation. The theoretical data was obtained for the bare L and for the [L−HgOH]+ and [L−Hg−L]2+ coordination compounds involved in the reaction mechanism in reported sensors. Calculations were performed with the Gaussian-98 program at the B3LYP/6-31G** level. A LANL2DZ pseudopotential was used for Hg. The calculated electrostatic potential of the ionophore has a maximum on the S atom and, with less intensity, on the Z-phenyl group; consistently, high negative charges occur on those sites. The two highest occupied molecular orbitals are also mainly located on the sulfur-Z-phenyl atoms. Thus, this region defines the active site. These results account for the softness of the S atom that is bonded to Hg2+ in the complexes. The metal−sulfur interaction is key in the observed selectivity of Hg2+ by L. However, a significant Z-phenyl-Hg2+ bonding was also found. This rather unexpected result suggests that Z-phenyl is crucial in the recognition of Hg2+. In fact, in [L−Hg−L]2+, two S atoms and two Z-phenyl groups carry the Hg2+ ion.

FT-IR, FT-Raman and ab-initio studies of 1,3-diphenyl thiourea

“…Theoretical study of the Hg 2+ recognition by 1,3-diphenylthiourea has been reported [2]. The mechanism of enantioselective Michael addition of acetylacetone to a nitroolefin catalyzed by a thiourea based chiral bifunctional organocatalyst is investigated using density functional theory calculations [3].…”

New Complexes with a Sterically Hindered Thiourea: Syntheses and Crystal Structures of [Co(dchtu)2Cl2], [Zn(dchtu)2(NCS)2] and [Pb(dchtu)6](SCN)2·2C2H5OH (dchtu = N,N′‐dicyclohexylthiourea)

“…Furthermore, their physical and chemical properties are modified by the substituents on nitrogen. Now, the chemistry of substituted thiourea derivatives has attracted increasing attention because of their potential use as reagents for the separation or recognition of metal ions [4,5] and in biological applications [6Ϫ8]. There have been many studies on N-alkyl or aryl and N,NЈ-dialkyl or diaryl substituted thioureas and related ligands coordinated to a series of metals [9Ϫ14].…”

Conformational and Topology Analysis of Diphenylthiourea and Diarylhalidethiourea Compounds Using DFT

“…The calculations were carried out using the Gaussian 09 suite of programs [17]. Previous electronic properties study on the other thiourea derivative molecules was proved reliable using B3LYP [18]. Thus, the single point calculations were performed at B3LYP level of theory with the DEF2-TZVP as the basis set.…”