Enhanced stability and colorimetric detection on Ag(I) ion of a methylthio-functionalized Zn(II) metal-organic framework

A tripodal linker with six pendant methylthio (–SCH3) groups was crystallized with Zn(II) ions to provide metal–organic framework (MOF) crystals, namely NOTT-6SMe-Zn, bearing three types of cage-like pores. NOTT-6SMe-Zn gives a highly distinguished color (dark brown) upon the introduction of Ag(I) ions, while it is insensitive towards other noble and transition metal ions. It exhibits a distinctly improved colorimetric detection of Ag(I) ions (e.g. as low as 30 ppm) and stability than that of non-methylthio functionalized NOTT-Zn. Better sensitivity is ascribed to the facile combination of soft sulfur atom and Ag(I) ions.