Second-Coordination-Sphere Assisted Selective Colorimetric Turn-on Fluoride Sensing by a Mono-Metallic Co(II) Hexacarboxamide Cryptand Complex
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 characterizati...
| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Chemistry Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/116626 https://orcid.org/0000-0001-9783-907X https://orcid.org/0000-0002-4507-1115 https://orcid.org/0000-0003-2568-3269 |
| Summary: | 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. |
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