Open Access Dissertation
Date of Award
Dinuclear metal complexes provide a route to interesting structure and reactivity. Two common uses of dinuclear metal complexes are sensing and activation of small molecules. Herein we describe a series of dinuclear metal complexes capable of sensing of oxalate and activation of carbon disulfide.
Sensing of oxalate is of great interest because high oxalate concentration (hypooxaluria) is a major cause of kidney stones. Dinuclear metal complexes can act as sensors for oxalate because the oxalate can bridge between the metal centers. Herein we describe a colorimetric oxalate sensor capable of regeneration. Upon addition of oxalate to a pink solution of a L1Ni2Br4 complex (L1= (1E,1′E)-N,N′-(1,4- phenylenebis(methylene))bis(1-(6-(2,4,6-triisopropylphenyl)pyridin-2-yl)methanimine) to a green solution of L1Ni2(C2O4)Br2. Due to this color change UV-vis titration was used to determine the binding constant of oxalate to be 5.2(5) x 102 M-1. Addition of CaBr2 to the green solution leads to the regeneration of the sensor by precipitation of Ca(C2O4).
Therefore we report the first example of an oxalate sensor capable of colorimetric detection of oxalate coupled with regeneration.
The synthesis of di-zinc macrocycles featuring bis(imino)pyridine chelating units linked by p-xylylene or m- xylylene linkers. Characterization of the compounds by NMR and X-ray structure determination revealed that the complexes were highly symmetrical (C2v or D2h). Cyclic voltammertry revealed that the combination of a redox-noninnocent ligand with a redox inactive metal stilled allowed the ligand to accept electron density. Oxalate extraction was unsuccessful with acetic acid, EDTA, and TMSCl. Attempts at extraction with CaBr2 lead to transformation of μ2-κ2,κ2-bound oxalate into the μ2-κ1,κ2- bound form. The addition of aqueous HCl to a macrocyclic complex showed oxalate free macrocycles by ESI-MS but any product was only transient and unable to isolated.
Activation of CS2 is of great interest because it is isoelectronic to CO2 and thus should similar reactivity. Herein we report the synthesis of a series of di-Ni complex capable of binding and activating CS2. DFT and X-ray revealed that the bound CS2 was two electron reduced, thus in order to induce reductive coupling of the two CS2 fragments oxidation was attempted with FeCp2(PF6). This however lead to liberation of the dinucleating ligand. Di-Cu(I) complexes were also synthesized however they showed no reactivity with CS2. More soluble mononuclear Ni(0) analogues were also synthesized that were also able to bind and activate CS2 however, reduction or oxidation by one electron yielded liberation of the free ligand as in the dinuclear complexes.
Beattie, Jeffrey William, "Synthesis Of Dinucleating Ligands And Their Dinuclear Metal Complxes:applications In Sensing And Small Molecule Activation" (2016). Wayne State University Dissertations. 1516.