Dual-mode colorimetric/fluorescent chemosensor for Cu/Zn and fingerprint imaging based on rhodamine ethylenediamine bis(triazolyl silsesquioxane).

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 and Zn 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. Remarkably, the addition of Cu triggered an enhanced fluorescent emission by 63.3-fold (ϕ = 0.41), while Zn enhanced it 48.3-fold (ϕ = 0.29) relative to the original RBS (ϕ = 0.006) in acetonitrile (MeCN) solvent. The fluorescent limit of detection for Cu and Zn is similar and fall within 3.0 nM, while under colorimetric sensing the responses were 2.14 × 10 and 4.0 × 10 mol L, respectively. Moreover, the effective sensing profile of RBS and extended applications of RBS-Cu and RBS-Zn for fingerprinting detection and imaging were observed with adequate sensitivity, stability and legibility under the dual visual responses.