Modification of a Single Atom Affects the Physical Properties of Double Fluorinated Fmoc-Phe Derivatives

Supramolecular hydrogels formed by the self-assembly of amino-acid based gelators are receiving increasing attention from the fields of biomedicine and material science. Self-assembled systems exhibit well-ordered functional architectures and unique physicochemical properties. However, the control over the kinetics and mechanical properties of the end-products remains puzzling. A minimal alteration of the chemical environment could cause a significant impact. In this context, we report the effects of modifying the position of a single atom on the properties and kinetics of the self-assembly process. A combination of experimental and computational methods, used to investigate double-fluorinated Fmoc-Phe derivatives, Fmoc-3,4F-Phe and Fmoc-3,5F-Phe, reveals the unique effects of modifying the position of a single fluorine on the self-assembly process, and the physical properties of the product. The presence of significant physical and morphological differences between the two derivatives was verified by molecular-dynamics simulations. Analysis of the spontaneous phase-transition of both building blocks, as well as crystal X-ray diffraction to determine the molecular structure of Fmoc-3,4F-Phe, are in good agreement with known changes in the Phe fluorination pattern and highlight the effect of a single atom position on the self-assembly process. These findings prove that fluorination is an effective strategy to influence supramolecular organization on the nanoscale. Moreover, we believe that a deep understanding of the self-assembly process may provide fundamental insights that will facilitate the development of optimal amino-acid-based low-molecular-weight hydrogelators for a wide range of applications.

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Controllable Synthesis of Cobalt Porphyrin Nanocrystals through Micelle Confinement Self-Assembly

MRS Advances ◽

10.1557/adv.2020.269 ◽

2020 ◽

Vol 5 (42) ◽

pp. 2147-2155

Author(s):

Sudi Chen ◽

Xitong Ren ◽

Shufang Tian ◽

Jiajie Sun ◽

Feng Bai

Keyword(s):

Self Assembly ◽

Water Oxidation ◽

Separation Efficiency ◽

Noncovalent Interactions ◽

Building Blocks ◽

The Self ◽

Hexagonal Prism ◽

Assembly Process ◽

Surfactant Micelles ◽

Cobalt Porphyrin

AbstractThe self-assembly of optically active building blocks into functional nanocrystals as high-activity photocatalysts is a key in the field of photocatalysis. Cobalt porphyrin with abundant catalytic properties is extensively studied in photocatalytic water oxidation and CO2 reduction. Here, we present the fabrication of cobalt porphyrin nanocrystals through a surfactant-assisted interfacial self-assembly process using Co-tetra(4-pyridyl) porphyrin as building block. The self-assembly process relies on the combined noncovalent interactions such as π-π stacking and axial Co-N coordination between individual porphyrin molecules within surfactant micelles. Tuning different reaction conditions (temperature, the ratio of co-solvent DMF) and types of surfactant, various nanocrystals with well-defined 1D to 3D morphologies such as nanowires, nanorods and nano hexagonal prism were obtained. Due to the ordered accumulation of molecules, the nanocrystals exhibit the properties of the enhanced capability of visible light capture and can conduce to improve the transport and separation efficiency of the photogenerated carriers, which is important for photocatalysis. Further studies of photocatalytic CO2 reduction are being performed to address the relationship between the size and shape of the nanocrystals with the photocatalytic activity.

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Co-assembly of helical β3-peptides: a self-assembled analogue of a statistical copolymer

Pure and Applied Chemistry ◽

10.1515/pac-2017-0709 ◽

2017 ◽

Vol 89 (12) ◽

pp. 1809-1816 ◽

Cited By ~ 2

Author(s):

Claire Buchanan ◽

Christopher J. Garvey ◽

Patrick Perlmutter ◽

Adam Mechler

Keyword(s):

Amino Acids ◽

Physical Properties ◽

Self Assembly ◽

Unnatural Amino Acids ◽

The Self ◽

Microscopy Imaging ◽

Wide Range ◽

Self Assembled ◽

Unnatural Peptides ◽

Natural Amino Acids

AbstractUnnatural peptide self-assembly offers the means to design hierarchical nanostructures of controlled geometries, chemical function and physical properties. N-acyl β3 peptides, where all residues are unnatural amino acids, are able to form helical fibrous structures by a head-to-tail assembly of helical monomers, extending the helix via a three point supramolecular hydrogen bonding motif. These helical nanorods were shown to be stable under a wide range of physical conditions, offering a self-assembled analogue of polymeric fibres. Hitherto the self-assembly has only been demonstrated between identical monomers; however the self-assembly motif is sequence-independent, offering the possibility of hetero-assembly of different peptide monomers. Here we present a proof of principle study of head-to-tail co-assembly of two different helical unnatural peptides Ac-β3[WELWEL] and Ac-β3[LIA], where the letters denote the β3 analogues of natural amino acids. By atomic force microscopy imaging it was demonstrated that the homo-assembly and co-assembly of these peptides yield characteristically different structures. Synchrotron small angle X-ray scattering experiments have confirmed the presence of the fibres in the solution and the averaged diameters from modelled data correlate well to the results of AFM imaging. Hence, there is evidence of co-assembly of the fibrous superstructures; given that different monomers may be used to introduce variations into chemical and physical properties, the results demonstrate a self-assembled analogue of a statistical co-polymer that can be used in designing complex functional nanomaterials.

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DABCO-Directed Self-Assembly of Pyrene-Centered Porphyrin Pentamers

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.575-576.123 ◽

2013 ◽

Vol 575-576 ◽

pp. 123-129

Author(s):

Zhuang Dong Yuan ◽

Jing Xia Wang ◽

Ning Sheng

Keyword(s):

Self Assembly ◽

Fluorescence Emission ◽

The Self ◽

Spectroscopic Methods ◽

Assembly Process ◽

Zinc Porphyrin ◽

Axial Coordination ◽

H Nmr ◽

Wide Range ◽

Nmr Techniques

DABCO (1, 4-diazabicyclo [2.2.2] octane) has been used in combination with pentameric zinc porphyrin-pyrene array 1 to form well-defined supramolecular arrays through axial coordination. The self-assembly process has been investigated by a wide range of spectroscopic methods including UV-vis, fluorescence emission and 1H NMR techniques.

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Tunable longitudinal modes in extended silver nanoparticle assemblies

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.7.113 ◽

2016 ◽

Vol 7 ◽

pp. 1219-1228 ◽

Cited By ~ 3

Author(s):

Serene S Bayram ◽

Klas Lindfors ◽

Amy Szuchmacher Blum

Keyword(s):

Silver Nanoparticle ◽

Self Assembly ◽

Aggregate Size ◽

Building Blocks ◽

Dipole Approximation ◽

The Self ◽

Nanoparticle Assemblies ◽

Longitudinal Modes ◽

Wide Range ◽

Experimental Findings

Nanostructured materials with tunable properties are of great interest for a wide range of applications. The self-assembly of simple nanoparticle building blocks could provide an inexpensive means to achieve this goal. Here, we generate extended anisotropic silver nanoparticle assemblies in solution using controlled amounts of one of three inexpensive, widely available, and environmentally benign short ditopic ligands: cysteamine, dithiothreitol and cysteine in aqueous solution. The self-assembly of our extended structures is enforced by hydrogen bonding. Varying the ligand concentration modulates the extent and density of these unprecedented anisotropic structures. Our results show a correlation between the chain nature of the assembly and the generation of spectral anisotropy. Deuterating the ligand further enhances the anisotropic signal by triggering more compact aggregates and reveals the importance of solvent interactions in assembly size and morphology. Spectral and morphological evolutions of the AgNPs assemblies are followed via UV–visible spectroscopy and transmission electron microscopy (TEM). Spectroscopic measurements are compared to calculations of the absorption spectra of randomly assembled silver chains and aggregates based on the discrete dipole approximation. The models support the experimental findings and reveal the importance of aggregate size and shape as well as particle polarizability in the plasmon coupling between nanoparticles.

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The Self-Assembly and Design of Polyfunctional Nanosystems

International Journal of Molecular Sciences ◽

10.3390/ijms22042223 ◽

2021 ◽

Vol 22 (4) ◽

pp. 2223

Author(s):

Ruslan Kashapov ◽

Lucia Zakharova

Keyword(s):

Sustainable Development ◽

Nanostructured Materials ◽

Self Assembly ◽

Building Blocks ◽

The Self ◽

Special Issue ◽

Molecular Building Blocks ◽

Wide Range ◽

Scientific Papers ◽

Current Task

The current task of the molecular sciences is to create unique nanostructured materials with a given structure and with specific physicochemical properties on the basis of the existing wide range of molecules of natural and synthetic origin. A promising and inexpensive way to obtain nanostructured materials is the spontaneous self-assembly of molecular building blocks during random collisions in real dispersive systems in solution and at interfaces. This editorial aims to summarize the major points from the 11 scientific papers that contributed to the special issue “The Self-Assembly and Design of Polyfunctional Nanosystems”, assessing the modern self-assembly potential and strategies for maintaining sustainable development of the nanoindustry.

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Supramolecular Alloys from Fluorinated Hybrid [4+6] Imine Cages

10.26434/chemrxiv.14192234.v1 ◽

2021 ◽

Author(s):

Tom Kunde ◽

Tobias Pausch ◽

Bernd M. Schmidt

Keyword(s):

Thermal Stability ◽

Self Assembly ◽

Gain Control ◽

Building Blocks ◽

The Self ◽

Feed Ratio ◽

Assembly Process ◽

Fluorinated Building Blocks ◽

Efficient Control ◽

Innovative Materials

To create innovative materials, efficient control and engineering of pore sizes and their characteristics, crystallinity and stability is required. Eight hybrid [4+6] imine cages with a tuneable degree of fluorination and one fully fluorinated [4+6] imine cage are investigated. Although the fluorinated and the non-fluorinated building blocks used herein differ vastly in reactivity, we are able to gain control over the outcome of the self-assembly process, by carefully controlling the feed ratio. This represents the first hybrid material based on fluorinated/hydrogenated porous organic cages (POCs). These alloys with unlimited miscibility in the solid state were obtained as highly crystalline samples after recrystallization and even showed retention of the crystal lattice. All alloys and the fully fluorinated [4+6] imine cage were analysed by MALDI-MS, SCXRD, PXRD and in regards to thermal stability (TGA). <br>

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Metallo-organic ensembles of tritopic subphthalocyanine ligands

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424617500882 ◽

2017 ◽

Vol 21 (12) ◽

pp. 782-789 ◽

Cited By ~ 1

Author(s):

M. Ángel Revuelta-Maza ◽

Ettore Fazio ◽

Gema de la Torre ◽

Tomás Torres

Keyword(s):

Mass Spectrometry ◽

Self Assembly ◽

Direct Injection ◽

Building Blocks ◽

The Self ◽

Assembly Process ◽

Text Structures ◽

Assembly Method ◽

Injection Techniques

Organic building blocks containing amines and aldehydes can be used for the preparation of complex metallo-organic structures, such as M[Formula: see text]L[Formula: see text] triple helicates or face-capped M[Formula: see text]L[Formula: see text] tetrahedral cages, through the formation of both dynamic covalent and coordinative linkages during the self-assembly process. Herein we describe how the subcomponent self-assembly method can be succesfully applied over a triamine-functionalized subphthalocyanine (SubPc) ligand to build metallo-supramolecular helicates. Two isomeric SubPcs (C[Formula: see text]-SubPc1 and C[Formula: see text]-SubPc1) have been prepared from the corresponding C[Formula: see text]-SubPcI[Formula: see text] and C[Formula: see text]-SubPcI[Formula: see text] precursors under optimized Suzuki conditions. We selected the tritopic C[Formula: see text]-SubPc1 derivative as ligand for the subcomponent self-assembly experiments, which involved the reaction with 2-formylpyridine and different Fe(II) salts. The self-assembly process was mainly studied by mass spectrometry (ESI direct injection techniques), and in all the conditions applied, we could observe the formation of helicate-type Fe[Formula: see text]SubPc[Formula: see text] structures and/or Fe[Formula: see text]SubPc[Formula: see text] species, which can be considered as open precursors of Fe[Formula: see text]SubPc[Formula: see text] tetrahedral cages.

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Influence of acidic media on the supramolecular aggregation of iso-tellurazole N-oxides

Canadian Journal of Chemistry ◽

10.1139/cjc-2015-0389 ◽

2016 ◽

Vol 94 (5) ◽

pp. 453-457 ◽

Cited By ~ 12

Author(s):

Peter C. Ho ◽

Lucia Myongwon Lee ◽

Hilary Jenkins ◽

James F. Britten ◽

Ignacio Vargas-Baca

Keyword(s):

Oxygen Atom ◽

Self Assembly ◽

Building Blocks ◽

The Self ◽

Assembly Process ◽

Acidic Media ◽

Protonated Molecules ◽

Supramolecular Aggregation ◽

Secondary Bonding

Iso-tellurazole N-oxides are promising supramolecular building blocks. While in neutral solutions, they form tetra- and hexameric macrocyclic aggregates linked by Te···O secondary bonding (σ hole interactions or chalcogen bonds), protonation of the oxygen atom in acidic media disrupts such supramolecular association. The process is reversible and, consequently, can be used to switch on and off the self-assembly process. Hammett acidity measurements gave pKa values of –3.2 for the protonated molecules. Adducts with HCl and HBr were isolated and structurally characterized. Protonation in solution led to the crystallization of a new polymorph of 3-methyl-5-phenyl-1,2-tellurazole N-oxide, which features a unique polymeric arrangement.

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