Colorimetric and fluorescence turn-on sensor for biologically important anions based on carbazole derivative

A colorimetric and fluorescent anion chemosensor containing carbazole group has been designed and synthesized based on photoinduced electron transfer (PET). The strong basic anions such as F−, AcO− and H2PO4− resulted in significant red-shift in absorption band and enhancement in fluorescent emission intensity of the compound 1, synchronously accompanied by a “naked eye” color change from light yellow to orange-yellow in organic medium. The determination limit of sensor 1 toward H2PO4− is 1.0 × 10− 6 mol·L− 1. 1H NMR titration experiments shed light on the nature of the interaction between 1 and the anions. Theoretical investigation further illustrated the possible binding mode of host–guest and the roles of molecular frontier orbitals in anion binding.

Graphical abstractA colorimetric and fluorescent anion chemosensor based on carbazole derivative has been designed and synthesized based on photoinduced electron transfer (PET). The strong basic anions such as F-, AcO- and H2PO4- resulted in significant red-shift in absorption band and increase in fluorescent emission intensity of the compound, synchronously accompanied by a “naked eye” color change from light yellow to orange-yellow in organic medium. The determination limit of sensor 1 toward H2PO4− is 1.0 × 10− 6 mol·L− 1. Theoretical investigation further illustrated the possible binding mode of host–guest and the roles of molecular frontier orbitals in anion binding.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Colorimetric and fluorescence turn-on sensor based on carbazole derivative. ► The interacted mechanism based on photoinduced electron transfer (PET). ► The red-shift in absorption band and increase in emission intensity for H2PO4−. ► The determination limit of the sensor toward H2PO4− is 1.0 × 10− 6 mol·L− 1. ► The roles of molecular frontier orbitals in anion binding.