Second-Coordination-Sphere Assisted Selective Colorimetric Turn-on Fluoride Sensing by a Mono-Metallic Co(II) Hexacarboxamide Cryptand Complex
Author(s)Stauber, Julia M.; Alliger, Glen Edward; Nocera, Daniel G; Cummins, Christopher C
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The preparation of a selective turn-on colorimetric fluoride sensor was achieved through single cobalt(II) ion insertion into a macrobicyclic cryptand. Monometallic [Co(mBDCA-5t-H₃)]− (1) and [Zn(mBDCA-5t-H₃)]− (2) complexes were prepared in 74 and 84% yields, respectively. Structural characterization of 1 confirmed the presence of a proximal hydrogen-bonding network consisting of carboxamide N–H donors. The reaction of 1 with F– was accompanied by a distinct colorimetric turn-on response in mixed aqueous/organic media, and 1 was capable of selective fluoride sensing in the presence of large quantities of potentially competitive anions. Complex 1 represents a unique example of a fluoride sensor wherein selective F– binding takes place directly at a transition-metal center and induces a color change based upon metal-centered transitions. The metal(II) fluoride complexes [F⊂Co(mBDCA-5t-H₃)]²– (3) and [F⊂Zn(mBDCA-5t-H₃)]²– (4) were both fully characterized, including single crystal X-ray analyses. Fluoride binding is synergistic involving hydrogen-bond donors from the second-coordination sphere together with metal(II) ion complexation.
DepartmentMassachusetts Institute of Technology. Department of Chemistry
American Chemistry Society
Stauber, Julia M., Glen E. Alliger, Daniel G. Nocera, and Christopher C. Cummins. “Second-Coordination-Sphere Assisted Selective Colorimetric Turn-on Fluoride Sensing by a Mono-Metallic Co(II) Hexacarboxamide Cryptand Complex.” Inorganic Chemistry 56, no. 14 (June 30, 2017): 7615–7619.
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