Study On The Complexation And Enantioselectivity Of Uranyl-HTTDN For R/S-organophosphorus Pesticides

It is of significance to explore the enantioselectivity of new uranyl receptors for chiral organophosphorus pesticides.In this paper,we designed a novel ligand:2-(2-hydroxy-3-methoxyphenyl)-9(2-hydroxyphenyl)thiopyrano[3,2-h]thiochromene-4,7-dione(HTTDN),and constructed a new receptor of Uranyl-HTTDN by complexation of HTTDN with uranyl.The coordination effect of Uranyl-HTTDN with two organophosphorus pesticides of R/S-methhamidophos(R/S-MAPs)and R/S-acephates(R/S-APs)were theoretically studied by using density functional theory(DFT)method,and further explored the enantioselective recognition between Uranyl-HTTDN and different coordination atoms of the two organophosphorus pesticide molecules in the first part of this paper.The results showed that in vacuum and toluene,Uranyl-HTTDN could effectively recognize R/S-MAPs by complexation with phosphoryl oxygen of methamidophos,with enatioselectivity coefficients of 91.80%and 86.74%,respectively.In vacuum,water and acetone,Uranyl-HTTDN could also effectively identify R/S-APs by the oxygen of phosphoryl coordinating with U,and enatioselectivity coefficients toward R/S-APs were 99.41%,91.09%and 93.84%,respectively.The second part of this paper theoretically studied the coordination of Uranyl-HTTDN with two chiral organophosphorus pesticides of R/S-prothiofos(R/S-PTFs)and R/S-profenofos(R/S-PFFs),and discussed the enantioselective recognition of Uranyl-HTTDN for R/S-PTFs and R/S-PFFs.The results showed that both the S3 atom of prothiofos and the O9 atom of profenofos could coordinate with the uranium atom of Uranyl-HTTDN.Under standard conditions,the coordination reaction between Uranyl-HTTDN and R/S-PTFs was incapable of occurring spontaneously in water,ethanol and 1-octanol.Uranyl-HTTDN had the highest selectivity to the enantiomer of R/S-PTFs in vacuum,and its enantioselectivity coefficient(F)was 96.87%;while under solvent conditions,the selectivity in toluene solvent was the largest,and its F value was 91.85%.The Δ(ΔG)value of R/S-PFF-O9-Uranyl-HTTDNs in solvents was:toluene<acetone<1-octanol<water<ethanol,indicating that the polarity of the solvent was smaller,and the possibility of coordination between Uranyl-HTTDN and R/S-PFFs was greater.In addition,the enantioselectivity coefficient of R/S-PFF-O9-Uranyl-HTTDNs in vacuum was 97.00%,and the enantioselectivity coefficients in ethanol,1-octanol,acetone and toluene were all over 91.00%.It showed that in vacuum,Uranyl-HTTDN had the greatest selectivity to the enantiomers of R/S-PFFs,and under solvent conditions,Uranyl-HTTDN could selectively recognize profenofos in R/S configuration by coordinating with the phosphoryl oxygen(O9)atom of R/S-PFFs,and had a relatively large selectivity in 1-octanol and toluene solvents.This work can provide valuable information for the separation of isomers of R/S-MAPs,R/S-APs,R/S-PTFs and R/S-PFFs,it can also provide theoretical supports for related experimental research on coordination chemistry of uranium.It will help to understand the selectivity of coordination recognition of Uranyl-HTTDN for chiral organophosphorus pesticides such as R/S-MAPs,R/S-APs,R/S-PTFs and R/S-PFFs.