Abstract
The impact of chirality on the self-assembly of supramolecular gels is of considerable importance, as molecular-scale programming can be translated into nanostructuring and ultimately affect macroscopic performance. This paper explores the effect of chirality on the assembly of two-component gels comprised of a second-generation dendritic lysine peptide acid, containing three chiral centres, and an amine. This combination forms an acid–amine complex that assembles into nanofibres through peptide-peptide hydrogen bonds, leading to organogels. With achiral amines, a racemic mixture of l,l,l and d,d,d dendritic peptide acids surprisingly forms the best gels—more commonly, mixing enantiomers suppresses gelation. Thermodynamic studies demonstrate that depending on the amine, the greater stability of heterochiral gels can either be entropically or enthalpically driven. With amines possessing “R” chirality, the l,l,l peptide acid consistently forms more effective gels than its d,d,d analogue. Furthermore, in mixed gels, l,l,l sometimes imposes its assembly preference onto d,d,d. In summary, this paper demonstrates a rare example in which heterochiral gels are preferred, and also explores directing effects when each component in a two-component gel is chiral.
Highlights
Supramolecular gels are soft materials in which molecular-scale building blocks self-assemble into nanoscale architectures that form a sample-spanning “solid-like” network and immobilise a bulk solvent [1,2,3,4,5,6,7,8]
One key molecular architectural feature is chirality, which has been the subject of considerable investigation—the chiral organisation of groups responsible for molecular recognition can have a significant impact on self-assembly [9,10,11,12]
We have studied a versatile two-component Type 1 gelation system based on the complex formed between a lysine dendron with an acid group at the focal point (G2-Lys, Figure 1), and amines [29,75,76,77,78,79,80]
Summary
Supramolecular gels are soft materials in which molecular-scale building blocks self-assemble into nanoscale architectures that form a sample-spanning “solid-like” network and immobilise a bulk solvent [1,2,3,4,5,6,7,8]. Buerkle and Rowan [18] classified multi-component gels into different types: Type 1 multi-component gels require two (or more) molecules to form a complex, which is responsible for self-assembly and gelation [21,22,23]. Such systems are highly tunable and responsive—for example, one component can select another from a dynamic mixture [24,25,26,27,28]. The gelators either self-sort into their own networks [30,31,32,33,34,35,36,37,38,39,40,41,42,43], co-assemble into a combined network [44,45,46,47], or inhibit/prevent
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
