We report here the formation of polycarbodiimide-g-polystyrene copolymer secondary structures, i.e. nano-rings, "craters", and spherical particles, resulted from dewetting phenomena that have been corroborated by combination of tapping mode AFM, SEM, DLS, and powder XRD techniques. These morphological findings represent certain interest in the area of novel functional materials. Well-defined ring-like aggregates are believed to be the transition motifs arising due to the concentration changes and, therefore, mainly seen when diluted CHCl3 stock solutions were used for AFM specimen preparation. Applying more polar THF or THF/EtOH (25% by volume) solvent systems influenced aggregation of grafted copolymers into spherical motifs with a particle size dependent on concentration that was also confirmed by dynamic light scattering (DLS) studies in solution. Characterization performed by electron microscopy techniques (SEM and TEM) provides evidence that AFM-observed morphologies do exist beyond the thin film phase and XRD findings are suggestive that non-covalent interactions of macromolecules play an important role in their self-organization in solid state. (C) 2016 Elsevier Ltd. All rights reserved.

A suite of branched-chain pyrogallol[4]arene (Pg) macrocycles, most of which show activity in bilayer membranes, has been prepared and studied by X-ray crystallography. The little-known branched side-chain Pgs include 2-propyl, 2-butyl, 2-pentyl, 3-pentyl, 3-heptyl, 4-heptyl, 5-nonyl and cyclohexyl. The Pgs form self-assembled structures having bilayer, capsule or, in one case, a nanotube morphology. The nanotube structure observed for C-(di-n-ethyl)pyrogallol[4]arene was confirmed by X-ray structure analysis and by transmission and scanning electron microscopies.

An extensive series of bis-oligobenzamides and bis-oligopyridylamides have been efficiently prepared and studied by X-ray analysis and computational methods. A modular synthesis led to double -helix mimics bearing between two and ten branched side-chains. The inter-helix angle and distance can be tuned by varying the length and rigidity of the spacer, thereby reproducing the recognition domains of a range of super-secondary structures.

Pyrogallolarenes are tetrameric macrocycles that form from 1,2,3-trihydroxybenzene and aldehydes under acidic conditions. When 2-ethylbutanal or 2-propyl-pentanal was so treated, the branched-chain pyrogallolarenes crystallized as nanotubes or bilayers, respectively. When the behavior of each compound was assessed by using the planar bilayer conductance method, pore formation was observed. The properties of the pores were significantly different from each other, probably reflecting different types of pore organization within the membrane.

Abstract The abnormal deposition of proteins as insoluble plaques is associated with many diseases, including Alzheimer’s, Parkinson’s and type II diabetes. There is an unmet need for synthetic agents that are able to mediate particular steps in the pathway between soluble proteins in their native unfolded state and their insoluble β-sheet rich aggregates. We have previously reported classes of α-helix mimetic that agonize or antagonize islet amyloid polypeptide aggregation, depending on the presence of a lipid bilayer. Here we investigate a novel mixed benzamide and pyridylamide scaffold that gives improved activity and explores the role of side-chain polarity, backbone rigidity and curvature in inhibiting lipid-catalyzed fibrillization. Graphical abstract

The synthesis of the family of new non-natural trimeric oligobenzamides (potential inhibitors of protein-protein interactions) bearing the following groups (R = isobutyl, isopropyl, CH2CONH2, (CH2)(4)NH2, benzyl) that mimic different amino acid residues (leucine, valine, asparagine, lysine, phenylalanine) was accomplished through an iterative (n + 1) elongation approach that includes reduction of the NO2-group (Pd/C, H-2) and subsequent amide coupling in the presence of Mukaiyama's reagent.

A facile method for the preparation of polycarbodiimide-based secondary structures (e. g., nano-rings, "craters," fibers, looped fibers, fibrous networks, ribbons, worm-like aggregates, toroidal structures, and spherical particles) is described. These aggregates are morphologically influenced by extensive hydrophobic side chain-side chain interactions of the singular polycarbodiimide strands, as inferred by atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. Polycarbodiimide-g-polystyrene copolymers (PS-PCDs) were prepared by a combination of synthetic methods, including coordination-insertion polymerization, copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) "click" chemistry, and atom transfer radical polymerization (ATRP). PS-PCDs were found to form specific toroidal architectures at low concentrations in CHCl3. To determine the influence of a more polar solvent medium (i. e., THF and THF/EtOH) on polymer aggregation behavior, a number of representative PS-PCD composites have been tested to show discrete concentration-dependent spherical particles. These fundamental studies are of practical interest to the development of experimental procedures for desirable architectures by directed self-assembly in thin film. These architectures may be exploited as drug carriers, whereas other morphological findings represent certain interest in the area of novel functional materials.

A series of new alpha-helix mimetics based on a benzamide scaffold and potentially able to disrupt protein-protein interactions have been synthesized and characterized by X-ray analysis. Inspection of the solid state structures of aromatic amide dimers confirmed that the molecules adopt a curved conformation with intramolecular H-bonding between the amide NH and the alkoxy oxygen of the neighboring aromatic fragment (d(NH center dot center dot center dot O) similar to 2 angstrom). Adjacent dimer molecules are prone to form supramolecular assemblies due to both hydrophobic alkyl side-chain/side-chain interactions and intermolecular H-bonding. (C) 2011 Elsevier Ltd. All rights reserved.

The self-assembly of pyrogallol[4]arenes resulted in the formation of hexameric capsules that trapped guest molecules present in solution, either within the capsule or within the pendant hydrocarbon chains. The results of analytical studies using FT-IR, (1)H NMR, (13)C NMR, TEM, TGA and HPLC are presented, along with the solid state structures of three hexameric capsules. Each of the capsules described has a large interior and includes various guest molecules.

A branched side chain pyrogallol[4]arene self-assembles into a previously-unreported cogged hydrogen-bonded nanotube structure in the solid state and self-assembles at the air-water interface on the Langmuir trough.

We report here the synthesis and self-assembly studies of a family of benzamide backbone oligomers bearing various alkyl side chains (e.g., isopropyl, isobutyl, and 2-ethylpentyl), which are potential alpha-helix mimetics capable of disrupting protein-protein interactions. Electron microscopy data (i.e., SEM and TEM concentration series) are indicative of the formation of various aggregates, such as micro-and nanofibers, and spherical beads, which are dominated by bis-oligoamide structures and may have resulted from intermolecular H-bonding, pi-pi stacking, and amide group dipole electrostatic attraction as evidenced by single crystal X-ray analysis. Thus, the aggregation behaviour was shown to depend on the number of repeat units in the oligoamide scaffold featuring elongated aggregates for bis-tetramers, whereas bis-dimers tend to form microspheres in a wide range of concentrations examined. We hypothesize that higher oligomers possessing an extended arylamide backbone are prone to efficiently crystallize with one another by interdigitation of their alkyl side chains leading predominantly to rod-like morphologies and fibrous crystals. The structural findings presented here can be potentially used in the rational design of supramolecular architectures based on arylamide peptidomimetics.