Octa-acid (OA) and tetra- endo -methyl octa-acid (TEMOA) are deep cavity cavitands that readily form multimeric complexes with hydrophobic guests, like n -alkanes, in aqueous solution. Experimentally, OA displays a monotonic progression from monomeric to dimeric complexes with n -alkanes of increasing length, while TEMOA exhibits a non-monotonic progression from monomeric, to dimeric, to monomeric, to dimeric complexes over the same range of guest sizes. Previously we have conducted simulations demonstrating this curious behavior arises from the methyl units ringing TEMOA's portal to its hydrophobic pocket barring the possibility for two alkane chains to simultaneously bridge between two hosts in a dimer. Here we expand our prior simulation study to consider the partially methylated hosts mono- endo -methyl octa-acid, 1,3-di- endo -methyl octa-acid, and tri- endo -methyl octa-acid to examine the emergence of non-monotonic assembly behavior. Our simulations demonstrate a systematic progression of non-monotonic assembly with increasing portal methylation. This behavior is traced to the progressive destabilization of 2 : 2 complexes (two hosts assembled with two guests) rather than stabilizing other potential host/guest complexes that could be formed.
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This content will become publicly available on July 16, 2025
An updated synthesis of octa-acid
Octa-acid 1 is a water-soluble cavitand that has been used to investigate hydrophobic solvation and Hofmeister effects, control photophysical and physicochemical properties, modulate the reactivity of encapsulated guests, and as a tool to engender novel separation protocols. The synthesis of 1 has largely centered around its formation from 2, a host that is itself most readily synthesized on the multi-gram-scale in crude form (>75% purity). In this Methods Article we reveal improvements in the synthesis of 2, as well as a new synthetic strategy that efficiently converts crude 2 into pure 1. This provides access to 1 in only a five-step linear sequence, shortening the total reaction time from previous methods, improving the purity, and increasing the final yield of 1. We therefore anticipate that the described protocols will be of interest to researchers seeking to utilize octa-acid in their studies.
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- Award ID(s):
- 2305018
- PAR ID:
- 10530835
- Publisher / Repository:
- Taylor and Francis
- Date Published:
- Journal Name:
- Supramolecular Chemistry
- ISSN:
- 1061-0278
- Page Range / eLocation ID:
- 1 to 4
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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