Search results for "supramolecular"

Existence of metastable intermediate lysozyme conformation highlights the role of alcohols in altering protein stability.

2011

Alcohols have a manifold effect on the conformational and thermodynamic stability of native proteins. Here, we study the effect of moderate concentrations of trifluoroethanol (TFE) on the thermal stability of hen egg-white lysozyme (HEWL), by far-UV circular dichroism and by steady-state and time-resolved photoluminescence of intrinsic tryptophans. Our results highlight that TFE affects lysozyme stability by preferential solvation of the protein molecule. Furthermore, we discovered the existence at 20% TFE of an equilibrium partially folded state of lysozyme, intermediate between the native and the unfolded state. A three-state model is therefore used to interpolate the thermal denaturation…

Subcomponent self‐assembly of a cyclic tetranuclear Fe(II) helicate in a highly diastereoselective self‐sorting manner

2019

Abstract An enantiomerically pure diamine based on the 4,15‐difunctionalized [2.2]paracyclophane scaffold and 2‐formylpyridine self‐assemble into an optically pure cyclic metallosupramolecular Fe4L6 helicate upon mixing with iron(II) ions in a diastereoselective subcomponent self‐assembly process. The cyclic assembly results from steric strain that prevents the formation of a smaller linear dinuclear triple‐stranded helicate, and hence, leads to the larger strain‐free assembly that fulfils the maximum occupancy rule. Interestingly, use of the racemic diamine also leads to a racemic mixture of the homochiral cyclic helicates as the major product in a highly diastereoselective narcissistic ch…

Supramolecular polymerization of sulfated dendritic peptide amphiphiles into multivalent L-selectin binders

2021

The synthesis of a sulfate-modified dendritic peptide amphiphile and its self-assembly into one-dimensional rod-like architectures in aqueous medium is reported. The influence of the ionic strength on the supramolecular polymerization was probed via circular dichroism spectroscopy and cryogenic transmission electron microscopy. Physiological salt concentrations efficiently screen the charges of the dendritic building block equipped with eight sulfate groups and trigger the formation of rigid supramolecular polymers. Since multivalent sulfated supramolecular structures mimic naturally occurring L-selectin ligands, the corresponding affinity was evaluated using a competitive SPR binding assay…

Thiourea Organocatalysts as Emerging Chiral Pollutants: En Route to Porphyrin-Based (Chir)Optical Sensing

2021

Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto’s catalyst), are widely used organocatalysts with virtually unknown environmental safety data. Ecotoxicity studies based on the Vibrio fischeri luminescence inhibition test reveal significant toxicity of Takemoto’s catalyst (EC50 = 7.9 mg/L) and its NH2-substituted analog (EC50 = 7.2–7.4 mg/L). The observed toxic effect was pronounced by the influence of the trifluoromethyl moiety. En route to the porphyrin-based chemosensing of Takemoto-type thioureas, their s…

Induced Chirality in Confined Space on Halogen Gold Complexes

2015

The solubilization of HAuCl4 in toluene within optically active reverse micelles and lamellar structures formed by (1R,2S)-Dodecyl(2-hydroxy-1-methyl-2-phenylethyl)- dimethylammonium bromide (DMEB) has allowed us to evidence the complex phenomenology accompanying the confinement of Au salt within these nanostructures. Together with a chloride/bromide exchange process occurring in the first coordination sphere of an Au ion, UV−vis and electronic circular dichroism (ECD) spectra reveal the appearance of an induced dichroic signal attributable to Au complexes entrapped in the hydrophilic domain of the DMEB chiral nanostructures. Interestingly, change of the effective oxidation state and coordi…

ChemInform Abstract: Pillar[n]arenes - A Novel, Highly Promising Class of Macrocyclic Host Molecules

2014

Review: [preparation, structure in solution and in the solid state and complexation; 100 refs.

Cover Picture: Complexation and Extraction of PAHs to the Aqueous Phase with a Dinuclear Pt II Diazapyrenium‐Based Metallacycle (Chem. Eur. J. 41/201…

2010

A conformationally adaptive macrocycle : conformational complexity and host–guest chemistry of zorb[4]arene

2018

Large amplitude conformational change is one of the features of biomolecular recognition and is also the basis for allosteric effects and signal transduction in functional biological systems. However, synthetic receptors with controllable conformational changes are rare. In this article, we present a thorough study on the host–guest chemistry of a conformationally adaptive macrocycle, namely per-O-ethoxyzorb[4]arene (ZB4). Similar to per-O-ethoxyoxatub[4]arene, ZB4 is capable of accommodating a wide range of organic cations. However, ZB4 does not show large amplitude conformational responses to the electronic substituents on the guests. Instead of a linear free-energy relationship, ZB4 foll…

Janus Micelles Induced by Olefin Metathesis

2008

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.

Copper(II)–Thymine Coordination Polymer Nanoribbons as Potential Oligonucleotide Nanocarriers

2016

This is the peer reviewed version of the following article: Vegas, V. G., Lorca, R., Latorre, A., Hassanein, K., Gómez‐García, C. J., Castillo, O., ... & Amo‐Ochoa, P. (2017). Copper (II)–Thymine Coordination Polymer Nanoribbons as Potential Oligonucleotide Nanocarriers. Angewandte Chemie International Edition, 56(4), 987-991, which has been published in final form at https://doi.org/10.1002/anie.201609031. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions