Chemistry & Biochemistry Colloquium | Cucurbit[8]uril-secured Platinum Dimers: Recognition and Applications, Nov. 21

The Chemistry & Biochemistry colloquium series presents Dr. Eric Masson discussing "Cucurbit[8]uril-secured Platinum Dimers: Recognition and Applications" on Nov. 21 from 4:10 to 5:05 p.m. in Walter 145.

Masson is Roenigk Chair and Professor & Department Chair of Chemistry & Biochemistry at Ohio University.

Abstract : We will discuss a new recognition motif in the Cucurbituril (CB[n]) family, namely the formation of CB[8]-secured head-to-head, “stacked” platinum terpyridyl (tpy) acetylide and thiolate dimers. Both positive Pt centers sit on top of each other at one CB[8] portal, leaving the other void of any guest interaction. ¹ Favorable dispersive interactions between the stacked tpy ligands and possible metal-metal bonding through d _z ² -d _z ² orbital overlap are proposed as driving forces for the recognition pattern. We will present some self-sorting properties of these assemblies ¹ and use them as catalysts for the photoreduction of water. ² We will conclude with a rather provocative study showing that the binding selectivity of CB[n]s (n = 5 – 8), at least when guests are hydrocarbons or noble gases, can be predicted by mimicking the macrocycles with hard-sphere solvents with low polarities and low polarizabilities and “pre-formed” cavities. ³

Figure 1. (a) Enhanced photoreduction of water catalyzed by a CB[8]-secured platinum dimer. (b) Orientation-specific self-assembly of Pt(II) acetylides with CB[8]. (c) “Dual layer” self-sorting between Pt thiolates and CB[8]. (d) A CB[8]-secured oligopeptide “pendant necklace”. (e) Cucurbiturils mimicked by low polarizability solvents with pre-formed cavities: an empirical model to predict hydrocarbon selectivity.

References

• Kotturi K., Masson, E. Eur. J. 2018 , 24 , 8670 – 8678; b) Barbero, H., Thompson, N. A., Masson, E. J. Am. Chem. Soc. 2020 , 142 , 867 – 873; c) Barbero, H., Masson, E., Chem. Sci. 2021 , 12 , 9962 – 9968.
• Rabbani, R., Saeedi, S., Nazimuddin, Md., Barbero, H., Kyritsakas, N., White, T. A., Masson, E. Sci. 2021 , 12 , 15347 – 15352.
• Rabbani, R.; Nazimuddin, Md; Barbero, H.; Masson, E. Chem. Sci. 2022 , 13 , 438