Dipyrromethene as multifunctional sensor towards d-metal cations

Multifunctional sensors are becoming increasingly important because a single such compound can be used to detect ions of two or more metals. We propose a 3,3 ' ,4,4 ' ,5,5 ' -hexamethyl-2,2 ' -dipyrromethene (HL) as multifunctional chemosensor for absorbance ratiometric detection of Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ ions, and fluorescent detection of Zn 2+ , Cd 2+ ions. The influence of the nature of complexing ion and medium on the thermodynamic stability of the [ML 2 ] complexes, chromophoric and fluorescent responses of complexation reactions was analyzed. The lg K o values of [ML 2 ] formation processes range from 4.72 to 11.08 and, regardless of the medium nature, increase in similar sequences of complexing agents: Cd 2+ , Ni 2+ , Hg 2+ , Co 2+ , Zn 2+ , Cu 2+ - in the c -hexane/propanol-1 (30:1, v/v) and Cd 2+ , Hg 2+ , Co 2+ , Zn 2+ - in DMF. The maximum fluorescent response ( I / I o = 100-150) was observed for the reaction of dipyrromethene with Zn 2+ ions. The reaction of HL with Cd (AcO) 2 is accompanied by a 10 -fold increase in fluorescence. Depending on the nature of the metal ion being determined and the medium, the detection limit of M 2+ ions reaches 5 x 10 -9 - 5 x 10 -8 mol/L. Test -systems as HL -doped cellulose tablets were developed for detecting trace amounts of Zn 2+ and Cd 2+ ions in aqueous solutions. The using 3,3 ' ,4,4 ' ,5,5 ' -hexamethyl-2,2 ' -dipyrromethene as a multifunctional chemosensor, both chromophore detection of Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ ions and "turn -on" fluorescent sensing trace amounts of Zn 2+ and Cd 2+ ions can be performed. Considering the significant differences in the chromophore-fluorescent characteristics of ligands and metal complexes, dipyrromethenes have great prospects for use in cation recognition.