Colorimetric bisulfite sensing and thio-amine click and declick reactions with applications in polymer chemistry and biotechnology

Sulfur dioxide and its derivative, bisulfite, are crucial components of food and wine because of their antioxidant and antibacterial properties. While these compounds, often referred to as “sulfites,” are important, their optimal concentration range is very narrow and exceeding it can cause adverse effects, ranging from altered taste to allergic reactions in consumers. The current internationally recognized methods used for sensing sulfites have drawbacks, such as lengthy procedures and low accuracy. Thus, the motivation of this research is to develop an efficient and more accurate technique for sensing sulfites. The initial approach was to couple the host-guest chemistry of cucurbiturils with the known reactivity of bisulfite with carbonyl compounds to cause a shift in λ [subscript max] of the complexes; however, a compound was found which could alone cause a color change upon reaction with bisulfite. Moreover, hydrogen peroxide was formed in the process and the current focus is to quantitatively measure the amount of peroxide generated to back-calculate the amount of bisulfite initially present. Separately, an important goal of organic chemistry has centered on the development of methods to assemble and disassemble molecular modules. The focus of this work is the development of a molecular tether to reversibly bind amines and thiols in aqueous conditions at neutral pH. Herein, are the details of reactions using a Meldrum’s acid-derived conjugate acceptor and its utility in peptide and polymer chemistries, which could greatly benefit from the introduction of reversible covalent bonding units. A current focus of pharmaceutical companies is the attachment of polyethylene glycol (PEG) groups to drugs and proteins to improve water solubility and increase hydrodynamic radius. However, high molecular weight PEG chains can bioaccumulate within the body. One focus of this work is the development of high molecular weight PEG chains that can be chemically triggered to break down into smaller units. In a separate field, a trend in the development of new bactericidal compounds is the use of antibacterial peptides that withstand decomposition through cyclization. Thus, another application of the aforementioned conjugate acceptor is the reversible cyclization of antibacterial peptides to both mask them from enzymes and modulate their activity.