Atomistic Simulations of COSAN: Amphiphiles without a Head‐and‐Tail Design Display "Head and Tail" Surfactant Behavior. Issue 8 (3rd January 2020)

• Record Type: Journal Article
• Authors: Malaspina, David C.; Viñas, Clara; Teixidor, Francesc; Faraudo, Jordi
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 8(2020)
• Page Start: 3088
• Page End: 3092
• Publication Date: 2020-01-03
• Subjects: COSAN -- molecular dynamics simulations -- nano-ions -- self-assembly; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201913257
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Cobaltabisdicarbollide (COSAN) anions have an unexpectedly rich self‐assembly behavior, which can lead to vesicles and micelles without having a classical surfactant molecular architecture. This was rationalized by the introduction of new terminology and novel driving forces. A key aspect in the interpretation of COSAN behavior is the assumption that the most stable form of these ions is the transoid rotamer, which lacks a "hydrophilic head" and a "hydrophobic tail". Using implicit solvent DFT calculations and MD simulations we show that in water, 1) the cisoid rotamer is the most stable form of COSAN and 2) this cisoid rotamer has a well‐defined hydrophilic polar region ("head") and a hydrophobic apolar region ("tail"). In addition, our simulations show that the properties of this rotamer in water (interfacial affinity, micellization) match those expected for a classical surfactant. Therefore, we conclude that the experimental results for the COSAN ions can now be understood in terms of its amphiphilic molecular architecture. Abstract : Tale of tails : Cobaltabisdicarbollide (COSAN) anions behave like a classical amphiphile in many respects, but behavior is unclear from the molecule architecture. Calculations reveal that in water the anion adopts a particular form (the cisoid rotamer), which has both a well‐defined hydrophilic region and a well‐defined hydrophobic region that can be clearly identified by simulations.