Dual-mode colorimetric/fluorescent chemosensor for Cu2+/Zn2+ 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 Cu2+ and Zn2+ 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 Cu2+. Remarkably, the addition of Cu2+ triggered an enhanced fluorescent emission by 63.3-fold (phi(F) = 0.41), while Zn2+ enhanced it 48.3-fold (phi(F) = 0.29) relative to the original RBS (phi(F) = 0.006) in acetonitrile (MeCN) solvent. The fluorescent limit of detection for Cu2+ and Zn2+ is similar and fall within 3.0 nM, while under colorimetric sensing the responses were 2.14 x 10(-8) and 4.0 x 10(-8) mol L-1, respectively. Moreover, the effective sensing profile of RBS and extended applications of RBS-Cu2+ and RBS-Zn2+ for fingerprinting detection and imaging were observed with adequate sensitivity, stability and legibility under the dual visual responses.

Automated summary

A novel dual functional and visual chemosensor, RBS, was successfully synthesized using click chemistry. The results demonstrated that RBS can detect Cu2+ and Zn2+ through fluorescent and colorimetric sensing. The fluorescent emission of RBS was significantly enhanced by 63.3-fold for Cu2+ and 48.3-fold for Zn2+ in acetonitrile solvent, with a detection limit of 3.0 nM. The colorimetric responses were 2.14 x 10(-8) and 4.0 x 10(-8) mol L-1 for Cu2+ and Zn2+, respectively.