Academic literature on the topic 'Self-Assembled p-Stacking'

Three cocrystals of acridine with 2,7-dihydroxynaphthalene (Ia and Ib) in two different polymorphs and 1,5-dihydroxynaphthalene (II) have been synthesized and characterized by single crystal x-ray diffraction method. Two polymorphs of acridine,2,7-dihydroxynaphthalene cocrystal crystallizes in same sapcegroup P-1 with different unit-cell parameters. In (Ia) the O‒H group form a syn-anti conformation whereas in (Ib) the O‒H group form an anti-anti conformation leads to the polymorphic structure of acridine, 2,7-dihydroxynaphthalene. This study reveals that the influence of π…π and C‒H…π interactions in the formation of one-, two-, and three-dimensional supramolecular frameworks when the classical hydrogen bonds such as O‒H…N and C‒H…O are limited to discrete motifs. The acridine molecules form continuous π…π stacking in the crystal structure of (Ia) and discrete π…π stacking in the crystal structure of (Ib) and (II). The conformational flexibility of the substituted hydroxy group has an influence in the supramolecular frameworks of the three-dimensional crystal structure. The intermolecular interaction energy calculation between the molecular pairs has been carried out to study the strength of the interaction and its dependence on the geometrical parameters.

A tetranuclear Cu^II complex composed of a doubly bpypz⁻ bridged dinuclear Cu^II complex with TCNQ˙⁻ self-assembles into a 3D supramolecular coordination architecture via complementary weak coordination bonding and π-stacking interactions.

The title compound, C12H13NO4, is one of the few examples that exhibits asynconformation between the amide and ester carbonyl groups of the oxalyl group. This conformation allows the engagement of the amide H atom in an intramolecular three-centred hydrogen-bondingS(6)S(5) motif. The compound is self-assembled by C=O...C=O and amide–π interactions into stacked columns along theb-axis direction. The concurrence of both interactions seems to be responsible for stabilizing the observedsynconformation between the carbonyl groups. The second dimension, along thea-axis direction, is developed by soft C—H...O hydrogen bonding. Density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) level of theory were performed to support the experimental findings.

Van der Waals (vdWs) heterostructures, assembled by stacking of two-dimensional (2D) crystal layers, have emerged as a promising new material system for high-performance optoelectronic applications, such as thin film transistors, photodetectors, and light-emitters. In this study, we showcase an innovative device that leverages strain-tuning capabilities, utilizing a MoS2/Sb2Te3 vdWs p-n heterojunction architecture designed explicitly for photodetection across the visible to near-infrared spectrum. These heterojunction devices provide ultra-low dark currents as small as 4.3 pA, a robust photoresponsivity of 0.12 A W−1, and reasonable response times characterized by rising and falling durations of 0.197 s and 0.138 s, respectively. These novel devices exhibit remarkable tunability under the application of compressive strain up to 0.3%. The introduction of strain at the heterojunction interface influences the bandgap of the materials, resulting in a significant alteration of the heterojunction’s band structure. This subsequently shifts the detector’s optical absorption properties. The proposed strategy of strain-induced engineering of the stacked 2D crystal materials allows the tuning of the electronic and optical properties of the device. Such a technique enables fine-tuning of the optoelectronic performance of vdWs devices, paving the way for tunable high-performance, low-power consumption applications. This development also holds significant potential for applications in wearable sensor technology and flexible electro-optic circuits.

1.Introduction Two-dimensional(2D) materials hold the promise to allow for ultrathin channels built of single atomic monolayers in ultimately scaled field-effect transistors (FETs). Due to this small thickness, an enhanced gate control is achieved while at the same time sizable mobilities in the 2D materials can be maintained[1]. In this way, the on-current density of the devices could potentially be increased to up to 1mA/μm by stacking six nanosheets on top of each other, combining p-type and n-type FETs in vertical integration. Even though FETs based on 2D materials hold a lot of promise, numerous challenges still need to be overcome. One of the most serious obstacles is the identification of a suitable gate stack. Over the last years, several insulators have been suggested, including layered insulators like hBN[2], ionic insulators like CaF2[3], amorphous high-k dielectrics like HfO2[4], see Fig.1. In addition, crystalline perovskites like SrTiO3[5] or native oxides like Bi2SeO5[6] have been explored. However, which of these materials provides the best performance is at the moment unclear and needs to be evaluated according to the criteria of scalability (Section 2), the minimization of charge traps (Section 3), and batch-processing compatible deposition technology for double-gated device designs (Section 4). 2.Scalable Gate Stacks High-performance FETs require a high on/off current ratio and steep subthreshold slopes. In order to preserve these characteristics in devices with ultimately scaled channel lengths, the insulator capacitance needs to be higher than 1.5μFcm-2, corresponding to a capacitive equivalent thickness smaller than 1nm. At the same time, if the insulator thickness becomes too small, the gate leakage current often easily exceeds the low-power limit of 0.015 Acm-2, thereby increasing the standby power consumption in the off-state. In fact, the gate leakage currents through thin hBN layers are high, rendering it unsuitable as a gate insulator for scaled FETs, while CaF2, HfO2 or Bi2SeO5 show promise[7]. 3.Minimizing Charge Traps The gate insulator should form a van der Waals interface with the 2D semiconductor, as otherwise, interface traps will degrade the carrier mobility and the sub-threshold slope[8]. Charge traps within the insulators cause limited stability and reliability of 2D FETs, as seen by a large hysteresis in the transfer characteristics or in Bias Temperature Instabilities. As a consequence, the stability can be enhanced if the defect bands in the gate insulator are energetically far away from the conduction and valence band edges[9]. Thus, the number of electrically active charge traps can be minimized by selecting a suitable combination of 2D semiconductor to insulator or by reducing the width of the defect bands by using crystalline insulators. 4.Deposition Technology Gate insulators need to be deposited on top of 2D semiconductors for top gate formation. However, the inert planes of 2D materials inhibit direct nucleation of insulators from the gaseous phase in an atomic layer deposition process. In this context, a promising approach is to use a self-assembled polymer monolayer to nucleate the precursors[4]. Molecular beam epitaxy is an alternative growth approach for gate insulators which offers the advantage of van der Waals epitaxy for layered materials, where the lattice-matching conditions are relaxed[10]. In order to avoid the growth of the insulator on top of the 2D semiconductor altogether the in-situ oxidation of the 2D semiconductor to its native oxide is a promising option, like for Bi2SeO5. 5.Conclusions Even though many novel insulator systems for 2D FETs have been proposed over the last couple of years, it is still unclear which of them best meets the requirements formulated. The most important questions to be addressed in the future will be to identify systems with reproducibly small interface and border trap densities and high thermal stability and to develop suitable batch-processing compatible top gate deposition methods for these material systems. Acknowledgments The authors thank for funding from the European Research Council under grant agreement no.101055379. References [1] S.Das et al., Nature Electronics 4, 786(2021). [2] T.Roy et al., ACS Nano 8, 6259(2014). [3] Y.Y.Illarionov et al., Nature Electronics 2, 8(2019). [4] W.Li et al., Nature Electronics 2, 563(2019). [5] A.J. Yang et al., Nature Electronics 5, 233(2022). [6] T.Li et al., Nature Electronics 3, 473(2020). [7] T.Knobloch et al., Nature Electronics 4, 98(2021). [8] T.Knobloch et al., Nanomaterials 12, 1(2022). [9] T.Knobloch et al., Nature Electronics 5, 356(2022). [10] L.A.Walsh et al., Applied Materials Today 9, 504 (2017). Figure 1: Schematic of a top-gated, scaled FET with an MoS2 channel and a HfO2 gate oxide. Figure 1

AbstractWe report noncovalent assemblies of iRGD peptides and methylene blue dyes via electrostatic and hydrophobic stacking. These resulting nanomaterials could bind to cancer cells, image them with photoacoustic signal, and then treat them via photodynamic therapy. We first assessed the optical properties and physical properties of the materials. We then evaluated their utility for live cell targeting, in vivo imaging, and in vivo photodynamic toxicity. We tuned the performance of iRGD by adding aspartic acid (DD) or tryptophan doublets (WW) to the peptide to promote electrostatic or hydrophobic stacking with methylene blue, respectively. The iRGD-DD led to 150-nm branched nanoparticles, but iRGD-WW produced 200-nm nano spheres. The branched particles had an absorbance peak that was redshifted to 720 nm suitable for photoacoustic signal. The nanospheres had a peak at 680 nm similar to monomeric methylene blue. Upon continuous irradiation, the nanospheres and branched nanoparticles led to a 116.62% and 94.82% increase in reactive oxygen species in SKOV-3 cells relative to free methylene blue at isomolar concentrations suggesting photodynamic toxicity. Targeted uptake was validated via competitive inhibition. Finally, we used in vivo bioluminescent signal to monitor tumor burden and the effect of for photodynamic therapy: The nanospheres had little impact versus controls (p = 0.089), but the branched nanoparticles slowed SKOV-3 tumor burden by 75.9% (p < 0.05).

Compared with Zn2+ storage, non‐metallic charge carrier with small hydrated size and light weight shows fast dehydration and diffusion kinetics for Zn−organic batteries. Here we first report NH4+/H+ co‐storage in self‐assembled organic superstructures (OSs) by intermolecular interactions of p‐benzoquinone (BQ) and 2, 6‐diaminoanthraquinone (DQ) polymer through H‐bonding and π‐π stacking. BQ‐DQ OSs exhibit exposed quadruple‐active carbonyl motifs and super electron delocalization routes, which are redox‐exclusively coupled with high‐kinetics NH4+/H+ but exclude sluggish and rigid Zn2+ ions. A unique 4e− NH4+/H+co‐coordination mechanism is unravelled, giving BQ‐DQ cathode high capacity (299 mAh g−1 at 1 A g−1), large‐current tolerance (100 A g−1) and ultralong life (50,000 cycles). This strategy further boosts the capacity to 358 mAh g−1 by modulating redox‐active building units, giving new insights into ultra‐fast and stable NH4+/H+ storage in organic materials for better Zn batteries.

Compared with Zn2+ storage, non‐metallic charge carrier with small hydrated size and light weight shows fast dehydration and diffusion kinetics for Zn−organic batteries. Here we first report NH4+/H+ co‐storage in self‐assembled organic superstructures (OSs) by intermolecular interactions of p‐benzoquinone (BQ) and 2, 6‐diaminoanthraquinone (DQ) polymer through H‐bonding and π‐π stacking. BQ‐DQ OSs exhibit exposed quadruple‐active carbonyl motifs and super electron delocalization routes, which are redox‐exclusively coupled with high‐kinetics NH4+/H+ but exclude sluggish and rigid Zn2+ ions. A unique 4e− NH4+/H+co‐coordination mechanism is unravelled, giving BQ‐DQ cathode high capacity (299 mAh g−1 at 1 A g−1), large‐current tolerance (100 A g−1) and ultralong life (50,000 cycles). This strategy further boosts the capacity to 358 mAh g−1 by modulating redox‐active building units, giving new insights into ultra‐fast and stable NH4+/H+ storage in organic materials for better Zn batteries.

Background: In the field of antibacterial, nanomaterials are favored by researchers because of their unique advantages. Medicinal plants, especially traditional Chinese medicine, are considered to be an important source of new chemicals with potential therapeutic effects, as well as an important source for the discovery of new antibiotics. MRSA is endangering people's lives as a kind of multidrug-resistant Staphylococcus aureus which are resistant to tetracycline, amoxicillin, norfloxacin and other first-line antibiotics. It is a hotspot to find good anti-drug-resistant bacteriae, nature-originated nanomaterials with good biocompatibility. Objective: We reported the formation of phytochemical nanoparticles (NPs) by the self-assembly of berberine (BBR) and 3,4,5-methoxycinnamic acid (3,4,5-TCA) from Chinese herb medicine, which had good antibacterial activity against MRSA. Method and Results: We found that NPs had good antibacterial activity against MRSA; especially, its antibacterial activity was better than first-line amoxicillin, norfloxacin and its self-assembling precursors on MRSA. When the concentration reached 0.1 µmol/mL, the inhibition rate of NPs reached 94.62%, which was higher than that of BBR and the other two antibiotics (p < 0.001). It was observed by field-emission scanning electron microscopy (FESEM) that NPs could directly adhere to the bacterial surface, which might be an important aspect of the antibacterial activity of NPs. Meanwhile, we further analyzed that the self-assembly was formed by hydrogen bonds and π-π stacking through ultraviolet−visible (UV-vis), fourier transform infrared spectroscopy (FT-IR), hydrogen nuclear magnetic spectrum (1 H NMR), and powder X-ray diffraction (pXRD). NPs’ morphology was observed by FESEM and TEM. The particles size and surface charge were characterized by dynamic light scattering (DLS); and the surface charge was -31.6 mv, which proved that the synthesized NPs were stable. Conclusion: We successfully constructed a naturally self-assembled nanoparticle, originating from traditional Chinese medicine, which had good antibacterial activity for MRSA. It is a promising way to obtain natural nanoparticles from medicinal plants and apply them to antibacterial therapy.

The paper describes the solid state structure of a compound of composition [Cu(bipy)3][Cu(bipy)(ala) (ClO4)2]ClO4, in which both the cation and anion are octahedral complex species with copper(II) as coordination center. The cation contains three chelate rings formed by bipy; the anion contains in the quatorial plane a CuONC2 chelate ring formed by the alaninato ligand and a CuN2C2 chelate ring formed by bipy, with two monodentate perchorato ligands in axial positions completing the six-coordination. In the crystal p-p stackings lead to a supramolecular self-assembled structure.

Le but de ce projet est de développer des modèles théoriques permettant d'étudier les transferts d'énergie à longue portée dans des systèmes biologiques auto-assemblés. Nous nous concentrons sur des empilements de phénanthrènes et de pyrènes encapsulés dans des brins d'ADN. Le choix de ces systèmes est motivé par de récentes expériences de spectroscopie à haute résolution spatio-temporelle, qui ont révélé le rôle important joué par le mécanisme de transfert excitonique. Les empilements de type π à base de phénanthrènes ont montré une capacité exceptionnelle pour le transport excitonique cohérent jusqu'à 150nm. À cette échelle, le transport est dû à un mécanisme mixte : d'une part à la délocalisation de l'exciton sur plusieurs unités de phénanthrènes et d'autre part aux sauts incohérents entre unités voisines. L'incorporation d'une unité de pyrène permet également de construire un système donneur-accepteur, dont l'unité pyrène terminale est désactivée par fluorescence. Ceci se produit à l'échelle de la nanoseconde et des processus comme l'absorption d'un photon menant le système hors d'équilibre, le transport d'excitons ou encore la fluorescence entrent en compétition avec la relaxation énergétique. Une étude préliminaire a été effectuée sur le plus petit modèle réalisé expérimentalement, un dimère de phénanthrène et de pyrène, caractérisant un bout de chaîne. La compétition temporelle entre processus photo-induits a été évaluée par une étude dynamique. Elle a permis la simulation de spectres de fluorescence résolus en temps, mis en relation avec la dynamique expérimentale. Les observations théoriques ont ainsi été corroborées par des hypothèses expérimentales. A des temps courts après l'excitation d'un phénanthrène, des processus de fluorescence anti-Kasha et Kasha ont été mises en avant. A des temps plus longs, une décroissance de la population du phénanthrène a été observée en faveur du peuplement du pyrène. Un fort signal de fluorescence Kasha a été observé sur ce fragment. En revanche, les limites du modèle ont été questionnées. En effet, l'expérience pose l'hypothèse d'un comportement délocalisé et cohérent au niveau du pyrène. Cependant, c'est un mécanisme local et incohérent qui domine les observations théoriques en bout de chaîne. Afin de faciliter l'interprétation de mécanismes cohérents dans des systèmes plus étendus, la recherche d'une caractérisation locale des excitations a été menée. Une méthode de diabatisation à partir d'états électroniques délocalisés a alors été élaborée. Une mesure de localisation a été développée, relatant l'efficacité de la méthode. Pour compléter la description locale de l'effet des couplages vibroniques, une étude perturbative a permis de déterminer les vibrations dominantes dans la relaxation vibrationnelle au sein du système. Des modes squelettiques ont montré une contribution importante à l'accélération de la dissipation vers l'état fondamental. Celles-ci ont été couplées aux degrés de liberté électroniques locaux afin de compléter la base vibronique locale. Un hamiltonien excitonique a alors été paramétré sous forme de blocs dans cette base locale et minimale adaptée à la description des transitions intramolélculaires et intermoléculaires. L'étude de systèmes réduits de phénanthrènes et de pyrènes ont permis de créer un modèle théorique pour l'étude du transfert d'énergie dans des polymères en chaîne. Son efficacité et sa pertinence ont été testées avec des calculs de dynamique cohérente d'excitons dans une base vibronique locale. Il comprend les outils préliminaires à l'étude de dynamique d'excitons dans des empilements étendus. Notamment, la description excitonique de l'hamiltonien facilite son extension à plus longue échelle. Celui-ci peut également être introduit dans un étude plus réaliste de dynamique quantique dissipative. Elle permet d'inclure divers effets menant à la décohérence et à la perte d'énergie, susceptibles d'impacter les transferts d'énergie
The goal of this project is to develop theoretical models to allow the study of long-range energy transfers in self-assembled biological systems. We will focus on phenanthrene/pyrene π-stacks embedded in a DNA scaffold. The choice of these specific systems is motivated by recent time-resolved spectroscopic experiments, which revealed the important role of the excitonic transfer mechanism. Phenanthrene-based π stacks have demonstrated an exceptional capacity for coherent excitonic transport up to 150nm. At this scale, the transport is due to a mixed mechanism : on the one hand to the delocalization of the exciton on several phenanthrene units, and on the other hand to incoherent jumps between neighboring units. The addition of a pyrene unit also allows the construction of a donor-acceptor system, whose terminal pyrene unit is quenched by nanosecond-scale fluorescence and the photo-excitation leading the system out of equilibrium, exciton transport and fluorescence processes are in competition with the energy relaxation. A preliminary study was carried out on the smallest model produced experimentally, a dimer of phenanthrene and pyrene, characterizing an end of an experimental chain. Temporal competition between photo-induced processes was evaluated by a dynamic study. It allowed the simulation of time-resolved fluorescence spectra, related to the dynamics observed experimentally. Then, theoretical observations were corroborated by experimental hypotheses. At short times after the excitation of a phenanthrene, processes of anti-Kasha and Kasha fluorescence on it were put forward. At longer time scales, a decrease in the population of phenanthrene was observed in favor of the population of pyrene. A strong Kasha fluorescence signal was observed for this fragment. On the other hand, the limits of the model were questioned. Indeed, the experiment poses the hypothesis of a delocalized and coherent behavior at the level of the pyrene. However, it is a local and incoherent mechanism that dominates theoretical observations at the end of the chain. In order to facilitate the interpretation of coherent mechanisms in larger systems, the search for a local characterization of the excitations was carried out. A diabatization method from delocalized electronic states has then been developed. A localization measure has been developed, reporting the effectiveness of the method. To complete the local description of the effect of vibronic couplings, a perturbative study made it possible to determine the dominant vibrations in the vibrational relaxation within the system. Skeletal vibrations of all the atoms of the same fragment showed an important contribution to the acceleration of the dissipation towards the ground state. These were coupled to the local electronic degrees of freedom in order to complete the local vibronic basis. An excitonic Hamiltonian was then parameterized and composed of blocks in this local and minimal basis suitable for the description of intramolecular and intermolecular transitions. The study of reduced stacks of phenanthrenes and pyrenes has made it possible to create a theoretical model for the study of energy transfer in chain polymers. Its efficiency and its relevance have been tested with calculations of coherent dynamics of excitons in a local vibronic base. It includes the preliminary tools for the study of exciton dynamics in extended stacks. In particular, the excitonic description of the Hamiltonian facilitates its extension on a longer scale. This can also be introduced into a more realistic study of dissipative quantum dynamics. It allows to include various effects leading to decoherence and energy loss, likely to impact energy transfers