Dual-mode colorimetric/fluorescent chemosensor for Cu2+/Zn2+ and fingerprint imaging based on rhodamine ethylenediamine bis(triazolyl silsesquioxane)

Abstract

Abstract A novel dual functional and visual rhodamine ethylenediamine bis(triazolyl silsesquioxane) ( RBS) chemosensor was successfully synthesized using “click” chemistry. The results have unambiguously demonstrated that RBS can act in fluorescent and colorimetric sensing of Cu 2+ and Zn 2+ by their respective coordination with triazole structures and, more importantly, it has also been found that triazole-amide of RBS could turn on chelation-enhanced fluorescence ( CHEF ) of Cu 2+ . Remarkably, the addition of Cu 2+ triggered an enhanced fluorescent emission by 63.3-fold ( ϕ F = 0.41), while Zn 2+ enhanced it 48.3-fold ( ϕ F = 0.29) relative to the original RBS ( ϕ F = 0.006) in acetonitrile (MeCN) solvent. The fluorescent limit of detection for Cu 2+ and Zn 2+ is similar and fall within 3.0 nM, while under colorimetric sensing the responses were 2.14 × 10 –8 and 4.0 × 10 –8 mol L −1 , respectively. Moreover, the effective sensing profile of RBS and extended applications of RBS–Cu 2+ and RBS–Zn 2+ for fingerprinting detection and imaging were observed with adequate sensitivity, stability and legibility under the dual visual responses. Graphical abstract