Structure–mechanical property relationship of a pentapeptide crystal

A peptide having miniature (P)310/α-helix conformation, forms intermolecular H-bonded supramolecular helical bundle structure which further self-assembled to interdigited supramolecular sheet-like structure that eventually from the brittle crystal.

Conformational Heterogeneity and Self-Assembly of α,β,γ-Hybrid Peptides Containing Fenamic Acid: Multistimuli-Responsive Phase-Selective Gelation

The effect of fenamic acid-α-aminoisobutyric acid corner motif in α,β,γ-hybrid peptides has been reported. From X-ray single-crystal diffraction studies, it is observed that Phe-containing peptide 1 has an "S"-shaped conformation that is stabilized by two consecutive intramolecular N-H···N hydrogen bonds. However, the tyrosine analogue peptide 2 has an "S"-shaped conformation, which is stabilized by consecutive intramolecular six-member N-H···N and seven-member N-H···O hydrogen bonds. The asymmetric unit of peptide 3 containing m-aminobenzoic acid has two molecules which are stabilized by multiple intermolecular hydrogen-bonding interactions. There are also π-π stacking interactions between the aromatic rings of fenamic acid. The peptides 1 and 2 have a polydisperse microsphere morphology, but peptide 3 has an entangled fiber-like morphology. Peptides 1-3 do not form organogels. However, in the presence of water, the peptide 3 forms a phase-selective instant gel in xylene. The gel exhibits high stability and thermal reversibility. The phase-selective gel of peptide 3 is highly responsive to H₂SO₄.

Role of water in the formation of unusual organogels with cyclo(leucyl-leucyl)

The key role of water in the formation of cyclo(leucyl-leucyl) organogels was demonstrated. The conditions required for preparation of previously unknown gels with aliphatic hydrocarbons at room temperature were determined. Cyclo(leucyl-leucyl) self-assembles to form different structures depending on the medium used. The molecular organization of gels was studied by the methods of microscopy, spectroscopy and X-ray powder diffractometry. The organogel of cyclo(leucyl-leucyl) can reversibly change volume during the heating/cooling cycle. We showed the possibility of practical application of cyclo(leucyl-leucyl) for water purification. The results obtained give a new insight into the mechanism of gelation with cyclo(dipeptide)-based low-molecular-weight gelators and may be useful for the preparation of new physical gels.

Tripeptide based super-organogelators: structure and function

The peptide based super-gelators are highly soluble in non-toxic organic solvent ethanol, the solution is easy to handle and just by spraying the ethanol solution over an oil–water mixture it is able to form an organogel at room temperature.

α,ε-Hybrid Peptide Foldamers: Self-Assembly of Peptide with Trans Carbon-Carbon Double Bonds in the Backbone and Its Saturated Analogue

The effect of geometrically rigid trans α,β-unsaturated ε-amino acids on the structure, folding, and assembly of α,ε-hybrid peptide foldamers has been reported. From single-crystal diffraction analysis, the unsaturated tetrapeptide 1 has stapler-pin-like structure but without intramolecular hydrogen bond. The asymmetric unit has two molecules that are stabilized by multiple intermolecular hydrogen bonding interactions as well as π-π stacking interactions between the aromatic rings of 3-aminocinnamic acid. Peptide 1 does not form organogel. But on hydrogenation, peptide 1 provides the saturated α,ε-hybrid peptide foldamer 2, which forms instant gel in most of the aromatic solvents. The gel exhibits high stability. The unsaturated peptide 1 has porous microsphere morphology, but saturated analogue 2 has ribbonlike morphology. The gel has been used efficiently for removal of cationic organic pollutants from waste water.

Photo-responsive modulation of hybrid peptide assembly, charge transfer complex formation and gelation

Light has been used as trigger for modulation of supramolecular assembly of hybrid peptides followed by charge transfer complex formation and organogelation.

Sonication-induced instant fibrillation and fluorescent labeling of tripeptide fibers

A sonication-induced instant fibril formation technique has been used for the co-assembly and fluorescent labeling of peptide nanofibers with organic dyes.

Influence of side-chain interactions on the self-assembly of discotic tricarboxyamides: a crystallographic insight

Side chains interactions promote the self-assembly of discotic tricarboxyamides to form an entangled fiber network and thermo responsive gel.

Self-assembly of β-alanine homotetramer: formation of nanovesicles for drug delivery

The present paper describes the fabrication of nanovesicles using the stirring induced self-assembly of a β-alanine homotetramer (H₂N–βAla–βAla–βAla–βAla–CONH₂) in an aqueous medium.

Supramolecular self-assemblies as functional nanomaterials

In this review, we survey the diversity of structures and functions which are encountered in advanced self-assembled nanomaterials. We highlight their flourishing implementations in three active domains of applications: biomedical sciences, information technologies, and environmental sciences. Our main objective is to provide the reader with a concise and straightforward entry to this broad field by selecting the most recent and important research articles, supported by some more comprehensive reviews to introduce each topic. Overall, this compilation illustrates how, based on the rules of supramolecular chemistry, the bottom-up approach to design functional objects at the nanoscale is currently producing highly sophisticated materials oriented towards a growing number of applications with high societal impact.

Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether as coupling reagent for peptide synthesis

Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether (4) was prepared by treatment of 2-hydroxy-4,6-dimethoxy-1,3,5-triazine with 2-chloro-4,6-dimethoxy-1,3,5-triazine in 61% yield. Ether 4, isoelectronic with pyrocarbonates, was found capable to activate carboxylic acids in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield, under mild reaction conditions, superactive triazine esters. Versatility of this new coupling reagent was confirmed by condensation of lipophilic and sterically hindered carboxylic acids with amines in 71-98% yield, and by synthesis of peptides, including those containing Aib-Aib sequence, in solution with high yield and high enantiomeric purity.