| Summary: | 碩士 === 國立中央大學 === 化學學系 === 107 === Here, we synthesized a series of Electron-Deficient Re(I) Tricarbonyl Complexes for anion recognition. Rhenium is the main coordination center in our compounds. The electron-deficient part is naphthalene diimides(NDI), which has a large positive quadrupole moment and is a well-known π-acidic aromatic ring for understanding the mechanisms of anion−π interactions. We designed and synthesized BppEb-Re-L2 (n = 2) and Bppb-Re-L2 (n = 1) with the different distances between the two NDI ligands, which are 9.108 Å and 8.798 Å. Furthermore, we designed and synthesized single rhenium complex BrRe(CO)3(L2)2 to make a comparison.
From anion sensing experiments, we could see there were two mechanisms when we added F–、CN– to BrRe(CO)3(L2)2、BppEb-Re-L2 solution. We conducted spectroelectrochemical analysis and EPR analysis of BrRe(CO)3(L2)2 and BppEb-Re-L2, and we could predict that there might have electron transfer from CN– to NDI due to the formation of NDI˙– and NDI2– which was observed in the UV-Vis absorption spectra too. From 1H NMR、19F NMR and Mass spectra, we could see the anion-π interactions between F–、CN– and complexes. The 19F NMR spectrum didn’t show any oxidation of F– to F˙, which indicated no electron transfer happened. Maybe it underwent charge transfer process.
Furthermore, we conducted several anion sensing experiments for L2 ligand. And we discovered that the sensing properties between L2 ligand and BrRe(CO)3(L2)2 were similar. But BppEb-Re-L2 is more sensitive to anion recognition than L2 ligand and BrRe(CO)3(L2)2. To sum up, we could point out that the distance between two NDI ligands will make a great influence on anion recognition. We can infer from above results that Bppb-Re-L2 might be the most sensitive anion sensor. And we can recognize F–、CN– easily with our anion sensors due to obvious color change.
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