Bioorganometallic chemistry is an emerging area of investigation in inorganic chemistry. Recent work has revealed that 1, a novel, bimetallic ring system, adopts and maintains a rigid conformation. This ring system possesses a ferrocene moiety at one end and a tungsten bis-alkyne complex at the other end. There are 28 protons in 1, and the 1H NMR spectrum shows 4 unique methyls from the dmtc ligands and a single resonance for each of the remaining 16 protons in the ring system. Thus there are 8 signals for the Cp H, 4 signals for the two methylenes, two signals for the alkyne H, and two signals for the amide NH. Similarly, there are 24 carbons in 1, and each one gives rise to a unique resonance in the 13C NMR spectrum. Thus, 1 possesses a remarkable asymmetry. In addition the conformation adopted by 1 is unchanged by either heating or cooling, indicating that the ring system has a rigid structure. Although 1 has yet to yield crystals suitable for X-ray analysis, it is thought that the two alkynes in 1 are positioned about 3.5 Å apart, which is approximately the same distance between the two peptide strands in a β-sheet. If this is true, then peptides appended to the two alkynes in 1 are likely to assume a β-sheet conformation. If these molecules do adopt β-sheet conformations, then they have the potential to serve as model systems for studying the forces that maintain or disrupt β-sheets, information that would help biomedical researchers investigating diseases (like Alzheimer's) that appear to be mediated by formation of β-sheet proteins. This presents a unique opportunity for inorganic chemistry to address a pressing issue in biochemistry. This presentation will detail the successes undergraduate students at Trinity College have had at preparing and evaluating peptide derivatives of 1 (for example 2 and 3), with an emphasis on their conformational behavior.

Synthesis and conformational analysis of peptides appended to a novel, rigid, cyclic, bimetallic ring system

253rd National Meeting (2017)

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