0000000000293776
AUTHOR
Hannah M. König
Solid-Phase Synthesis of Oligo(p-benzamide) Foldamers
[reaction: see text] A coupling protocol has been developed which allows the synthesis of oligo(p-benzamide)s on solid support. Aromatic carboxylic acids are activated in situ with thionyl chloride and used to acylate secondary aromatic amines. N-p-Methoxy benzyl (PMB) as well as N-hexyl protected monomers were investigated. Heterosequences of both monomers were synthesized. Such nanoscale objects are important building blocks for supramolecular chemistry.
Supramolecular PEG-co-oligo(p-benzamide)s prepared on a peptide synthesizer.
An automated synthesis protocol has been developed for the preparation of oligo(p-benzamide)s on solid support using a commercial peptide synthesizer employing a variation of standard Fmoc chemistry. Bis(trichloromethyl carbonate) in NMP was used to activate the aromatic carboxylic acids for acylation of secondary aromatic amines on solid support. N-Protected hepta(p-benzamide) was automatically prepared on solid support and manually converted to a solid supported block co-oligomer by attaching a poly(ethylene glycol) chain. Cleavage from the support could be achieved with minimal loss of the p-methoxybenzyl N-protective group. While the N-protected block co-oligomer was molecularly dissolv…
Automated Large-Scale Synthesis of Supramolecular Oligo(p-benzamide) Block Copolymers
A fully automated large-scale synthesis procedure has been developed that allows the preparation of supramolecular rod−coil copolymers on a 100 g scale. The new reaction cycle allows the stepwise growth of oligo(p-benzamide)s onto the chain end of amine-terminated polymers. Amine-terminated poly(ethylene glycol) (PEG, Mn = 5000 g mol-1) and poly(styrene) (PS, Mn = 2950 g mol-1) were prepared, and an octa(p-benzamide) oligomer block was grown from the chain end in an automated computer-controlled reaction cycle. Plotting the apparent molecular weight of the PEG copolymer against the number of reaction cycles revealed a linear relationship, which emphasized the high level of control this meth…
Learning from nature: beta-sheet-mimicking copolymers get organized.
The solution structures formed by coil-coil copolymers arise from the selective solvation of one of the two blocks and have been well described. In most cases in such relatively simple synthetic structures there are no specific attractive forces that can aid the aggregation process. Nature, however, provides plenty of inspiring polymeric architectures that are shaped and ordered hierarchically by noncovalent forces. The high level of structural definition displayed by proteins, for example, is unmatched by synthetic polymers. An emerging area of interest in polymer science tries to combine the best of both worlds, the natural and the synthetic, by conjugating synthetic polymers and beta-she…
Der Natur abgeschaut: β-Faltblatt-Oligopeptide und Analoga organisieren Blockcopolymere
Die Strukturen von Knauel-Knauel-Diblockcopolymeren in Losung lassen sich durch die selektive Solvatation einzelner Blocke erklaren und sind mittlerweile gut untersucht. In den meisten Fallen verfugen diese relativ einfach aufgebauten Blockcopolymere uber keinerlei spezifische attraktive Wechselwirkungen, die einen Aggregationsprozess unterstutzen konnten. Demgegenuber sind in der Natur unzahlige Beispiele definierter polymerer Architekturen zu finden, die hierarchisch uber nichtkovalente Wechselwirkungen aufgebaut sind. Hoch definierte Strukturen, wie sie etwa die Proteine bilden, sind fur synthetische Polymere bislang unbekannt. Ein relativ junges Forschungsgebiet der Polymerchemie widmet…
An Improved Rapid Synthesis of Oligo(p -benzamide) Block Copolymers
We describe a new synthesis that allows the preparation of oligo(p-benzamide)s up to the heptamer on solid support without the need of semi-temporary amide N-protective groups. With increase in length, the solubility of oligo(p-benzamide)s reduces dramatically. Even the tetra(p-benzamide) is not soluble in common organic solvents. Therefore, solution syntheses of oligomers beyond the tetramer are not feasible. As will be shown in this paper, solid supported synthesis allows the preparation of even longer oligomers (up to the heptamer) in good yields. The high dilution on the solid support is most likely responsible for their pseudo-solution-like reactivity and the prevention of aggregation.…
Janus Micelles Induced by Olefin Metathesis
A facile one-step procedure for hydrophobic modification and simultaneous TEM contrast enhancement via a regioselective olefin metathesis reaction using Grubbs' catalyst is presented. Polyether diblock copolymers were investigated, and both the chain ends of the hydrophilic and the hydrophobic block were hydrophobically modified. Modification of the hydrophilic block results in nonsymmetric supramolecular structures (Janus micelles) which self-assemble into larger hierarchically organized super-micelles.