Self-Assembly of a Structurally Defined Chiro-Optical Peptide–Oligothiophene Hybrid Material (original) (raw)
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Macromolecules, 2017
The development of chiral optoelectronic materials are of great interest due to their potential of being utilized in electronic devices, biosensors and artificial enzymes. Herein, we report the chiral-optical properties and architectural arrangement of optoelectronic materials generated from non-covalent self-assembly of a cationic synthetic peptide and five chemically defined anionic pentameric oligothiophenes. The peptide-oligothiophene hybrid materials exhibit a three dimensional ordered helical structure and optical activity in the π-π* transition region that are observed due to a single chain induced chirality of the conjugated thiophene backbone upon interaction with the peptide. The latter property is highly dependent on electrostatic interactions between the peptide and the oligothiophene, verifying that a distinct spacing of the carboxyl groups along the thiophene backbone is a major chemical determinant for having a hybrid material with distinct optoelectronic properties. The necessity of the electrostatic interaction between specific carboxyl functionalities along the thiophene backbone and the lysine residues of the peptide, as well as the induced circular dichroism of the thiophene backbone, was also confirmed by theoretical calculations. We foresee that our findings will aid in designing optoelectronic materials with dynamic architectonical precisions, as well as offer the possibility to create the next generation of materials for organic electronics and organic bioelectronics.
Chemistry: A European Journal, 2018
Supramolecular chemistry has evolved from the traditional focus on thermodynamic on-pathways to the complex study of kinetic off-pathways, which are strongly dependent of the environmental conditions. Moreover, the control over pathway complexity allows obtaining nanostructures that are inaccessible through spontaneous thermodynamic processes. Here, we present a family of peptide-based π-extended tetrathiafulvalene (exTTF) molecules which show two self-assembly pathways leading to two distinct J-aggregates, namely metastable (M) and thermodynamic (T), with different spectroscopic, chiroptical and electrochemical behavior. Moreover, cryo-transmission electron microscopy (cryo-TEM) reveals a different morphology for both aggregates and a direct observation of the morphological transformations from tapes to twisted ribbons.
Advanced Materials, 2009
Investigation of self-organization behavior of organic (semi)conductors became very important recently, since their physical properties and performance in organic electronic devices strongly depend on ordering effects, on both molecular and nanoscale levels. [1] In this respect, bioinspired functionalization of conjugated systems might greatly enhance the diversity of electronically interesting assemblies, and potentially allow for the rational design of hierarchically ordered nanostructures. Thus, from possible hybrids of conjugated backbones, the combination of oligo-or polythiophenes with biomolecules, such as nucleotides, [3] carbohydrates, or peptides, are interesting. Particularly, the latter appears to be attractive, because interplay between different intermolecular forces in the peptide and oligothiophene segments results in competing self-assembly motifs. Hence, very specific organization properties can be expected. Whereas thiophene-based materials typically form well-organized 2D lamellar superstructures due to van der Waals interactions of alkyl side chains, and stack into the third dimension via p-p interactions, [6] secondary structures of peptides, preferentially bsheets or a-helices, are governed by stronger and directed hydrogen-bond formation. The high tendency of peptides to adopt well-defined secondary-structure motifs has been exploited recently to guide self-organization of a broad range of synthetic polymers. [8] Attention has mainly been devoted to the b-sheet motif, leading to anisotropic fibrillar or fiber-like structures. [9] However, other highly interesting assembly motifs, for example the coiled-coil motif, were exploited, resulting in distinct nanoobjects by the lateral assembly of amphiphilic a-helices. We recently presented the first conjugate between a regioregularly alkylated quaterthiophene and a pentapeptide consisting of a silk-inspired sequence of alanine-glycine repeats, which is known to adopt b-sheet structures. [5a] Unexpected and novel 3D nanostructures were found, suggesting that short peptide sequences may indeed influence the nanoscale structure, and ultimately, properties of organic semiconducting materials.
Solvent-Induced Supramolecular Assembly of a Peptide-Tetrathiophene-Peptide Conjugate
Frontiers in Chemistry
The assembly of a peptide-tetrathiophene-peptide (PTP) conjugate has been investigated in mixed solvents, which has different polarities by changing the solvent proportions. It was found that PTP can form fibers in THF/hexane solutions with 40-80%v of hexane. The fibers were stable and did not change on time. On the other hand, PTP formed ordered structures in a mixed solution with the water content from 40 to 60%v. For the as-prepared solutions, two nanostructures vesicles and parallelogram sheets were obtained. The parallelogram sheets could transform into vesicles on time. The fibers showed supramolecular chirality, however, there was no Cotton effect for vesicles and parallelogram sheets. UV-vis, FL, XRD, FT-IR, and CD spectra together with SEM, AFM, TEM were used to characterize the nanostructures and properties of the assemblies. Molecular packing mechanism was proposed based on the experimental data.
Collection of Czechoslovak Chemical Communications, 2022
Biomimetic chiral optoelectronic materials can be utilized in electronic devices, biosensors and artificial enzymes. Herein, this work reports the chiro-optical properties and architectural arrangement of optoelectronic materials generated from selfassembly of initially nonchiral oligothiopheneÀ porphyrin derivatives and random coil synthetic peptides. The photo-physicaland structural properties of the materials were assessed by absorption-, fluorescence-and circular dichroism spectroscopy, as well as dynamic light scattering, scanning electron microscopy and theoretical calculations. The materials display a three-dimensional ordered helical structure and optical activity that are observed due to an induced chirality of the optoelectronic element upon interaction with the peptide. Both these properties are influenced by the chemical composition of the oligothiopheneÀ porphyrin derivative, as well as the peptide sequence. We foresee that our findings will aid in developing self-assembled optoelectronic materials with dynamic architectonical accuracies, as well as offer the possibility to generate the next generation of materials for a variety of bioelectronic applications.
Self-organizing bioinspired oligothiophene–oligopeptide hybrids
Beilstein Journal of Nanotechnology, 2011
In this minireview, we survey recent advances in the synthesis, characterization, and modeling of new oligothiophene-oligopeptide hybrids capable of forming nanostructured fibrillar aggregates in solution and on solid substrates. Compounds of this class are promising for applications because their self-assembly and stimuli-responsive properties, provided by the peptide moieties combined with the semiconducting properties of the thiophene blocks, can result in novel opportunities for the design of advanced smart materials. These bio-inspired molecular hybrids are experimentally shown to form stable fibrils as visualized by AFM and TEM. While the experimental evidence alone is not sufficient to reveal the exact molecular organization of the fibrils, theoretical approaches based on quantum chemistry calculations and large-scale atomistic molecular dynamics simulations are attempted in an effort to reveal the structure of the fibrils at the nanoscale. Based on the combined theoretical and experimental analysis, the most likely models of fibril formation and aggregation are suggested.
Responsive Supramolecular Polythiophene Assemblies
Journal of the American Chemical Society, 1998
The simple preparation of a novel family of smart polymers based on acid-base complexes between an acidic conjugated polymer (poly(2-(4-methyl-3-thienyloxy)ethanesulfonic acid)) and various amine-containing molecules is described. The neutralization of the acid form of the polymer can be monitored optically in real time through the decrease of the 800 nm absorption band, characteristic of a self-acid-doped state. Moreover, by electrostatically binding adequate responsive substituents, thermochromic, ionochromic, photochromic, and biochromic materials have been easily developed. These optical features seem related to a conformational change of the conjugated main chain driven by side-chain disordering. Furthermore, aminosilane-treated substrates can undergo further modification through electrostatic interactions with partially pre-neutralized polymers, yielding very efficient electrochemical solid-state sensors. It is believed that such a simple methodology, based on electroactive and photoactive supramolecular polymeric assemblies, may open the way to the design of integrated chemical systems incorporating both a trigger and a transducer and can find applications in the areas of biosensors, drug screening, and diagnostics.
Journal of Peptide Science, 2011
The photocurrent generation properties of mono-and bi-component peptide-based self-assembled monolayers (SAMs) immobilized on a gold surface were studied by electrochemical and spectroscopic techniques. The peptides investigated comprised almost exclusively C α-tetrasubstituted α-amino acids. These non-coded residues, because of their unique conformational properties, forced the peptide backbone to attain a helical conformation, as confirmed by X-ray crystal structure and CD determinations in solution. The peptide helical structure promoted the formation of a stable SAM on the gold surface, characterized by an electric macrodipole directed from the C(δ −) to the N(δ +) terminus, that remarkably affected the electron transfer (ET) process through the peptide chain. The peptides investigated were derivatized with chromophores strongly absorbing in the UV region to enhance the efficiency of the photocurrent generation (antenna effect). The influence of the nature of the peptide-gold interface on the ET process (junction effect) was analyzed by comparing the photocurrent generation process in peptide SAMs immobilized on a gold surface through Au-S linkages with that in a bi-component SAM embedding a photoactive peptide into the linked palisade formed by disulfide-functionalized peptides.
Supramolecular Electronic Coupling in Chiral Oligothiophene Nanostructures
Advanced Materials, 2006
Understanding and controlling supramolecular organization in polymeric semiconductor materials is central for their exploitation in electronic devices. For example, regioregular poly(3-hexylthiophene) (rr-P3HT) chains can self-assemble into lamellae, which results in effective field-effect mobilities of the order of 0.1 cm 2 V -1 s -1 compared to mobilities several orders of magnitude lower in more disordered morphologies. Quasi-steady-state and time-resolved spectroscopic studies of rr-P3HT and related polythiophene derivatives firmly establish that the nature of photoexcitations is fundamentally different in regioregular versus regiorandom materials. These differences extend to the direct charge photogeneration efficiency and the 3D delocalization of charged excitations, both of which are suggested to be higher in rr-P3HT films. However, the extent of intermolecular electronic interaction in rr-P3HT still remains elusive. Studies on oligothiophene crystals indicate that the intermolecular electronic interactions can be substantial compared to intramolecular reorganization energies (placing these systems in the so-called "intermediate" electronic coupling regime ) and that important differences in the consequences of these interactions are expected for oligomers with odd and even numbers of monomer units. Cofacial arrangement of conjugated molecules into stacked aggregates is expected to result in energetic splitting of the highest occupied and lowest unoccupied molecular levels, producing new possible optical transitions between the resulting highest occupied state and the split excited states. If the supramolecular arrangement is perfectly cofacial, the lowest energy transition is predicted to be symmetry forbidden. Importantly, semiempirical quantum-chemical calculations show that the intermolecular electronic coupling decreases with increasing length of the molecules that form the H aggregate. This would predict a nearly vanishing electronic interaction term in well-ordered rr-P3HT films.