Synthesis of new chromogenic sensors containing thiourea and selective detection for F-, H2PO4-, and Ac- anions

摘要

Two new chromogenic sensors 1-(2-hydroxyphenyl)-3-(4-nitrophenyl)thiourea 1 and 1-(3-hydroxypyridin-2-yl)3-(4-nitrophenylithiourea 2 bearing nitrophenyl and thiourea groups were designed and synthesized by one-step procedure and characterized through H-1 NMR, C-13 NMR, FTIR, and MS. The anion recognition property of the receptors was studied via naked-eye detection, UV-vis, and H-1 NMR. Based on the existence of amino gen and hydroxyl moieties in receptors, receptors 1 and 2 exhibit obvious selectivity by the redshift of UV-vis signals, colour changes through naked-eye detection, and binding effects for F-, H2PO4-, and Ac-. Surprisingly, the detection limits of receptor 1 for F- and Ac- were calculated to be 5.45 x 10(-7) and 2.11 x 10(-7) (mol/L)(-1), respectively, which indicated that F- and Ac- can be identified with high sensitivity by receptor 1. Besides, simple "test strips" were developed and were used as sensors for recognition of F-, H2PO4-, or Ac- in DMSO solution. Lastly, the mechanisms of the recognition process were studied through DFT calculation and H-1 NMR titration.