Theoretical Investigation Into Coordination And Selectivity Of Uranyl-Unilateral Benzotriazole Salophens(X=O/S) For Triadimefons And Triadimenol

The design of new uranyl-Ligands（uranyl-Ls）is of great significance for the separation and utilization of uranium.In this paper,triazole group was introduced into uranyl-Salophen（uranyl-S）to form new asymmetric uranyl-unilateral benzotriazole Salophen（uranyl-UBS）;we further replaced two oxygen atoms of uranyl-UBS with two sulfur atoms to generate uranyl-unilateral benzotriazole thio-Salophen（uranyl-UBTS）as a new receptor.In the first part,we comprehensively explored coordination models of uranyl-UBS and uranyl-UBTS with R/S-triadimefons（R/S-TDFs）enantiomers as the guests using density functional theory（DFT）calculations at B3LYP//RECP/6-311G**level;we then investigated enantioselectivity recognition of the new receptors to the guests R/S-TDFs.The results indicated that the uranium atoms of the receptors uranyl-S,uranyl-UBS and uranyl-UBTS could coordinate with the carbonyl oxygens in guests R/S-TDFs to form complexes of guest-receptors R/S-TDFs-uranyl-Ls that exhibited two stable V-shaped structures with quite different properties.It was found that the coordination ability to the guests R/S-TDFs is uranyl-UBTS>uranyl-UBS>uranyl-S,while the enantioselectivity for the guests is uranyl-UBTS>uranyl-S>uranyl-UBS,and when the receptor is the same,R-TDF has stronger coordination ability than S-TDF.The second part in paper investigated the coordination of RR/SS/RS/SR-triadimenols（TDNs）with a novel-designed host of uranyl-unilateral benzotriazole thio-Salophen（Uranyl-UBTS）.The relationships of coordination models to the structural and chemical properties of four complexes,including their bond length,bond order,molecular orbitals,weak interaction,infrared spectrum,and molecular polarity,were discussed comparing with previous literature work.Furthermore,the enantioselectivity of Uranyl-UBTS to RR/SS-TDNs and RS/SR-TDNs are investigated by the selectivity coefficient.All theoretical calculations were carried out using density functional theory（DFT）calculatons at the level of B3LYP/RECP/6-311G**.The results indicated that all the coordinations of host with guests took place between the hydroxyl oxygens in the TDNs and uranium in the Uranyl-UBTS.Because of the difference of conjugation system between the left and right side of the host theπ-πstacking interactions exist in the host-guest complexes RR-TDN-Uranyl-UBTS,RS-TDN-Uranyl-UBTS and SS-TDN-Uranyl-UBTS,but there is no theπ-πstacking interactions in SR-TDN-Uranyl-UBTS.The structure of SR-TDN-Uranyl-UBTS optimized is the most compact;the heights of infrared absorption peak of C-OH and C-O-C in SR-TDN-Uranyl-UBTS were relatively similar,and the values of dipole moment and molecular polarity index（MPI）of SR-TDN-Uranyl-UBTS were the smallest.All of those prove that the polarity of SR-TDN-Uranyl-UBTS was the smallest.The U-O₃ in Complexes RR/SR are stronger than those in Complexes RS/SS,and Complexes RR/SR are more stable than Complexes RS/SS.The order of binding energy is:UUBTS-RR-TDN>SR-TDN-Uranyl-UBTS>RS-TDN-Uranyl-UBTS>SS-TDN-Uranyl-UB TS.Uranyl-UBTS has very good selectivity for RR/SS-TDNs and RS/SR-TDNs,and the values of selectivity coefficients（F）in the vacuum,benzene,and methanol solvent models are all greater than98.5%.These results provide information and theoretical supports for the experiments of asymmetric uranyl-UBTS with TDF and TDN,lay a reference for further exploring the coordination characteristics of asymmetric uranyl-Salophen with the triazole derivatives.