Electron-accepting Properties Research Articles

Adding multiple electrons to helicenes: how they respond?

Helicenes of increasing dimensions and complexity have recently burst into the scene due to their unique structures coupled with interesting chiral, optical, and conducting properties. The helicene-related research has quickly progressed from fundamental curiosity to a diverse range of applications in organic catalysis, optoelectronic devices, chiroptical switches, sensors, and energy storage. The in-depth understanding of electron accepting properties of helicenes should further advance their materials chemistry applications, however, previous reports only relied on spectrocopic and electrochemical studies, while their structural changes weren't extensively discussed. Therefore, we initiated a broad investigation of chemical reduction behaviour of helicenes ranging in size and properties coupled with X-ray diffraction characterization of the reduced products. The responses of helicenes with different structures to the stepwise electron addition were investigated using a combination of X-ray crystallography, spectroscopic methods, and calculations. This study revealed topology- and charge-dependent consequences of chemical reduction ranging from reversible geometry perturbation to irreversible core transformation and site-specific reactivity of helicenes in addition to original alkali metal coordination patterns. This overview is focused on the crystallographically confirmed examples stemming from chemical reduction reactions of different helicenes with alkali metals. The opened discussion should stimulate further exploration of reactivity and complexation of novel π-expanded and heteroatom-doped helicenes based on the revealed structure-property correlations, thus advancing their applications as intriguing new materials.

A DFT study on antimonene as a drug delivery vehicle for carmustine, lomustine and nitrosourea anticancer drugs

We used antimonene (Sb) as a delivery vehicle for transporting drugs like Carmustine (CMT), Lomustine (LOMU) and Nitrosourea (NU) in both gaseous and liquid states. The Sb nanosheet structure is stable, and its potential for drug adsorption has been investigated in both parallel and perpendicular directions. The parallel configuration is most stable with a higher adsorption energy of −1.18 eV, −0.63 eV and −1.14 eV for LOMU, CMT and NU respectively. We investigated structural parameters, electronic properties, work function and chemical reactivity. Only NU alters the Sb’s semiconductor behaviour to metallic and has the shortest recovery time in the parallel direction. Hirshfield charge analysis revealed that nanosheet displays electron accepting properties, whereas drugs act as electron donors. The decreased work function for CMT and LOMU enhances substrate activity, indicating stronger interactions that may improve drug delivery. We confirmed the drug’s effective interaction with amino acids without impairing proteins. Furthermore, calculated results predicted a minimal acidic environment of malignant growth, CM, NU and LOMU drugs could start to release from the Sb surface without significantly altering the structural properties. This study illustrates how Sb nanosheet holds promise as an effective carrier for drug delivery in biomedical applications.

Hearing triboelectricity: home experiments

Abstract This study explores the demonstration of triboelectricity using everyday materials in a home experiment setting. By rubbing Teflon against metallic electrodes (aluminum and copper), we generated significant voltage due to Teflon’s strong electron acceptor properties. Aluminum exhibited higher voltage generation than copper, attributed to a greater electron affinity difference. To showcase practical applications, we successfully illuminated LEDs and powered a Bluetooth speaker, using the voltage generated from Teflon-metal interactions. This simple yet effective setup highlights the potential of triboelectric materials for sustainable energy harvesting and underscores the accessibility of home-based experiments in advancing scientific understanding.

Spectroscopic, anti-cancer, anti-bacterial and theoretical studies of new bivalent Schiff base complexes derived from 4-bromo-2,6-dichloroaniline

In this paper, four new mono-nuclear Ni(II), Pd(II), Pt(II) and Zn(II) complexes were prepared by using a bi-dentate Schiff base ligand, (E)-2-(((4-bromo-2,6-dichlorophenyl)imino)methyl)-5-chlorophenol (BrcOH), with bivalent ions in a methanol and distil water mixture as solvent in presence of NaOH as base. The structures of the prepared compounds were characterized by spectroscopic techniques (IR and 1H NMR), CHN analysis, and molar conductivity. The M(II) (Ni, Pd and Pt) ions are four-coordinated by a bi-dentate N2O2 donor ligand, forming square planar geometry, whereas the Zn(II) is coordinated as a tetrahedral geometry. The newly synthesized compounds, which include the Schiff base ligand and its complexes, underwent antibacterial screening against E. coli and S. aureus. The results demonstrated a remarkable and noteworthy biological activity of these compounds against these pathogenic bacterial strains. Different binding energies showed good correlation, with Pd showing the strongest binding. Small energy differences indicated high reactivity, with Ni and Pd complexes being the most reactive. Electrophilicity index exhibited electron-accepting properties, with Zn showing the highest reactivity. The dipole moments showed polarity and charge separation, with Pt having the highest polarity. We evaluated the pharmacokinetic properties (ADME) of a ligand and its metal complexes using the Swiss ADME website. The results of the in-silico prediction of physicochemical properties revealed that ten compounds in total adhered to Lipinski's rule.

Porous polyselenoviologen with long-lived charge separated states and highly cyclic stability for heterogeneous photocatalytic reaction and hydrogen production

A highly stable heterogeneous photocatalyst, porous polyselenoviologen (POP-SeV2+), was successfully synthesized via SN2 reaction. Compared to the monomer, POP-SeV2+ exhibited strong visible-light absorption, enhanced electron acceptor property, and prolonged lifetime of radical cations. Simultaneously, the femtosecond transient absorption (fs-TA) illustrated that the formation of tetrahedral multi-cationic structure is conducive to the rapid generation of molecular excited states and extending the duration of charge-separated states. Due to its remarkable characteristics, the POP-SeV2+ was employed as a photocatalyst for visible-light-induced cross-dehydrogenative coupling (CDC) reactions with a highly efficient yield (82 %). Additionally, its utilization was further extended to the hydrogen generation, demonstrating remarkable outcomes such as a high rate of H2 generation (300 μmol·h−1·g−1), and an apparent quantum yield (0.13 %). Notably, POP-SeV2+ displayed great stability and reusability in the photocatalytic process, which can distinguish it from those soluble SeV2+-based photocatalysts. The catalytic efficiency of POP-SeV2+ remained virtually unaffected even after undergoing several recycling cycles, which not only achieved the complete heterogeneous photocatalysis of SeV2+-based systems for the first time but also provided a new strategy to improve the application effect of viologen derivatives in solar energy conversion and utilization.

A mechanistic investigation of non-covalent interactions induced by selenium and alkoxy substitution in the structural and photoelectric properties of non-fused ring electron acceptors

The pivotal role of non-covalent interactions has been increasingly acknowledged by researchers in the intricate design and advancement of non-fused ring electron acceptors (NFREAs). This surge in attention arises from their profound influence on the facilely twisted molecular geometries and critical photoelectric attributes inherent to organic solar cells (OSCs). In this study, various selenium atoms and alkoxy groups were strategically introduced into the well-performing NFREA A4T-16, leading to the creation of molecules denoted as Se-1 to Se-9 and O1 to O9. Utilizing density functional theory (DFT) and time-dependent density functional theory (TD-DFT), a comprehensive analysis of these molecules was conducted, encompassing factors such as intramolecular non-covalent interactions, the fill factor (FF), and the open-circuit voltage (VOC). The electronic structures and photovoltaic characteristics of these molecules underwent a thorough investigation to elucidate the intricate mechanisms governing non-covalent interactions within NFREAs, thereby clarifying their functional significance. The findings disclose that acceptor molecules featuring selenium substitution display notably augmented Se∙∙∙O and S∙∙∙O non-covalent interactions, exceeding the strength observed in their alkoxy-substituted derivatives. This results in the selenium-substituted derivatives boasting superior overall planarity, narrower energy gaps, reduced excitation energies, and broader absorption bandwidths, thereby enhancing their charge transfer characteristics compared to A4T-16. Conversely, the alkoxy-substituted acceptor molecules display higher fill factor (FF) and superior open-circuit voltage (VOC) relative to the selenium-substituted derivatives. Notably, the innermost substitutions at O6, O7, and O9 show the most promising outcomes, potentially indicating optimal power conversion efficiency (PCE).

Correction: Enhanced Electron-accepting Properties in Polyaniline, Tungsten, and Polymer Nanocomposites

Correction: Enhanced Electron-accepting Properties in Polyaniline, Tungsten, and Polymer Nanocomposites

Highly Tribo-Positive Nylon-11 Film Fabricated by Multiscale Structural Regulation through a Roll-to-Roll Processing.

Triboelectric polymers have attracted extensive attention due to their great electron-accepting and electron-donating properties in contact electrification as well as their flexible and low-cost merits and have become promising electrode materials in triboelectric nanogenerators (TENGs). However, most research has exclusively focused on improving the electron capture capability of the triboelectric layer, neglecting to enhance the electron-donating capability, which leads to a low output performance of TENG and limits its practical application. In this study, we developed a method to fabricate highly tribo-positive Nylon-11 film through roll-to-roll processing. Paired with the poly(tetrafluoroethylene) triboelectric layer, the transferred charge density of contact-separation TENG based on Nylon-11 film prepared by this method reaches 291.1 μC/m2, which has been improved by 12.4% compared with the conventional compression molding sample. The novel fabricating method can regulate the surface functional groups to achieve higher surface potential and obtain a favorable pseudohexagonal crystal phase, leading to an increasing transferred charge density in triboelectrification. Additionally, it has been analyzed that higher chemical potential of materials can facilitate the transfer of electrons from the triboelectric polymer surface. This study provides a nonadditive, simple, and effective strategy to fabricate excellent tribo-positive material, which can significantly enhance the performance of TENG.

Tuning Electron-Accepting Properties of Phthalocyanines for Charge Transfer Processes.

Phthalocyanines play fundamental roles as electron-acceptors in many different fields; thus, the study of structural features affecting electron-accepting properties of these macrocycles is highly desirable. A series of low-symmetry zinc(II) phthalocyanines, in which one, three, or four benzene rings were replaced for pyrazines, was prepared and decorated with electron-neutral (alkylsulfanyl) or strongly electron-withdrawing (alkylsulfonyl) groups to study the role of the macrocyclic core as well as the effect of peripheral substituents. Electrochemical studies revealed that the first reduction potential (Ered1) is directly proportional to the number of pyrazine units in the macrocycle. Introduction of alkylsulfonyl groups had a very strong effect and resulted in a strongly electron-deficient macrocycle with Ered1 = -0.48 V vs SCE (in THF). The efficiency of intramolecular-charge transfer (ICT) from the peripheral bis(2-methoxyethyl)amine group to the macrocycle was monitored as a decrease in the sum of ΦΔ + ΦF and correlated well with the determined Ered1 values. The strongest quenching by ICT was observed for the most electron-deficient macrocycle. Importantly, an obvious threshold at -1.0 V vs SCE was observed over which no ICT occurs. Disclosed results may substantially help to improve the design of electron-donor systems based on phthalocyanines.

NIR-II Absorption/Fluorescence of D-A π-Conjugated Polymers Composed of Strong Electron Acceptors Based on Boron-Fused Azobenzene Complexes.

Luminescence in the second near-infrared (NIR-II, 1,000-1,700 nm) window is beneficial especially for deep tissue imaging and optical sensors because of intrinsic high permeability through various media. Strong electron-acceptors with low-lying lowest unoccupied molecular orbital (LUMO) energy levels are a crucial unit for donor-acceptor (D-A) π-conjugated polymers (CPs) with the NIR-II emission property, however, limited kinds of molecular skeletons are still available. Herein, D-A CPs involving fluorinated boron-fused azobenzene complexes (BAz) with enhanced electron-accepting properties are reported. Combination of fluorination at the azobenzene ligand and trifluoromethylation at the boron can effectively lower the LUMO energy level down to -4.42 eV, which is much lower than those of conventional strong electron-acceptors. The synthesized series of CPs showed excellent absorption/fluorescence property in solution over a wide NIR range including NIR-II. Furthermore, owing to the inherent solid-state emissive property of the BAz skeleton, obvious NIR-II fluorescence from the film (up to λFL=1213 nm) and the nanoparticle in water (λFL=1036 nm, brightness=up to 29 cm-1 M-1) were observed, proposing that our materials are applicable for developing next-generation of NIR-II luminescent materials.

Naphthalene diimide-Annulated Heterocyclic Acenes: Synthesis, Electrochemical and Semiconductor Properties and their Multifaceted Applications.

Acenes and Naphthalene Diimides (NDIs) stand as distinguished classes of organic compounds, each possessing unique and intriguing properties that have garnered significant attention across various scientific disciplines. Acenes, characterized by linearly fused aromatic rings, have captivated researchers due to their diverse electronic structures and promising applications in materials science. On the other hand, NDIs, known for their distinctive electron-accepting properties, exhibit remarkable versatility in fields ranging from organic electronics, supramolecular to spin chemistry. In this review, we navigate through the fascinating realms of both acenes and NDIs before converging our focus on the highly diverse and distinctive subgroup of NDI-annulated heterocyclic acenes. This potentially important subgroup, has emerged as a subject of intense investigation, encapsulating their fascinating synthesis, optical and electrochemical characteristics, and multifaceted applications that span the realms of chemistry, physics, and biology. Through the exploration of their synthetic strategies, unique properties, and diverse applications, this review aims to offer a comprehensive understanding of the pivotal role played by NDI-based heterocyclic acenes in contemporary multidisciplinary research and technological innovation.

Wavily Curved Perylene Diimides: Synthesis, Characterization, and Photovoltaic Properties.

Solubility enhancement is a key issue for developing the perylene diimide-based functional materials. Introduction of curved structure proved an effective solubilizing method without employing steric repulsion. In this work, wavily curved perylene diimides were developed as a new family of highly soluble curved perylene diimides. Moreover, their conformational dynamics, aggregating properties, electronic properties, and photovoltaic performances were thoroughly examined in comparison to the previously reported isomer exhibiting an arched curvature. The waved isomer demonstrated heightened rigidity and a greater propensity for aggregation compared to the arched isomer, likely attributed to its more planar structure. Each benzoxepin unit played a role in cancelling out the curvature on the opposite side. While the difference in the molecular curvature did not cause significant alterations in the photophysical and electron-accepting properties, we identified that the modulation of the curved structure is effective in controlling the morphology of the photoelectric conversion layer.

Harnessing benzotriazole as a sustainable ligand in metal-catalyzed coupling reactions.

Coupling reactions play a crucial role in drug development enabling the rapid expansion of structure-activity relationships (SARs) during drug discovery programs to identify a clinical candidate and simplify subsequent drug development processes. In particular, their relevance in clinical medicine and drug discovery has increased significantly in the last two decades. To facilitate these metal-catalyzed coupling reactions, suitably designed ligands are necessary and from the industrial point of view, sustainable and cost-effective ligands are of current need. Benzotriazole, a non-toxic, thermally stable, and inexpensive bidentate ligand, exhibits strong electron donating and electron accepting properties, along with excellent solubility in various organic solvents. It has been extensively explored as a synthetic auxiliary in the past; in recent years, benzotriazole and its derivatives have been used as ligands in metal-catalyzed coupling reactions. The facile construction of carbon-carbon and carbon-heteroatom bonds in the presence of versatile benzotriazole ligands makes it an indispensable ligand for catalytic transformations. The present feature article mainly emphasizes the advances in the utilization of benzotriazole as a ligand in a diverse range of C-C, C-N, C-O, and C-S coupling reactions.

Synthesis and comparative study of (NHCF)PdCl2Py and (NHCF)Ni(Cp)Cl complexes: investigation of the electronic properties of NHC ligands and complex characteristics.

The electron-donating and electron-accepting properties of N-heterocyclic carbene (NHC) ligands play a pivotal role in governing their interactions with transition metals, thereby influencing the selectivity and reactivity in catalytic processes. Herein, we report the synthesis of Pd/NHCF and Ni/NHCF complexes, wherein the electronic parameters of the NHC ligands were systematically varied. By performing a series of controlled structure modifications, we elucidated the influence of the σ-donor and π-acceptor properties of NHC ligands on interactions with the transition metals Pd and Ni and, consequently, the catalytic behavior of Pd and Ni complexes. The present study deepens our understanding of NHC-metal interactions and provides novel information for the rational design of efficient catalysts for organic synthesis.

Contact electrification controlled by material deformation-induced electronic structure changes

The effective control of triboelectricity through material development is crucial for the safety of electronics and human well-being. However, owing to the absence of fundamental research on the mechanism of triboelectricity, material development has stagnated in this regard. In this study, we investigated the deformation effect on triboelectric behavior to enable a comprehensive understanding of the contact electrification mechanism. Theoretical results demonstrated that deformation leads to a reduction in the energy level associated with electron-accepting properties, thereby enhancing the tribonegative behavior of tribonegative materials. Conversely, the energy level related to electron-donating properties decreases, resulting in a waning of the tribopositive behavior of tribopositive materials. The experimental results further demonstrated that, consistent with the theoretical results, increased deformation induces an enhancement in the output of tribonegative materials while decreasing the output of tribopositive materials. Our findings provide a fundamental basis for controlling triboelectricity and advancing the development of stagnant triboelectric materials.

Construction of fluorescent sensor array and three-dimensional microfluidic paper based analytical device for specific identification and visual determination of antibiotics in food.

For antibiotics misuse since the global outbreak of COVID 19, a novel strategy for discriminating and detecting antibiotics is proposed based on the graphene quantum dots with multi-doped heteroatoms including F, N and P (M-GQDs), which exhibit blue emission (419.0nm) under the excitation of 336.0nm. Specifically, the fluorescence of M-GQDs is quenched by tetracyclines (TCs) owing to inner filter effect (IFE) and enhanced by alkane-modified fluoroquinolones (AFQs), which is attributed to restricted conformational rotation based on π-π stacking, hydrogen-bonding and electrostatic interactions. Meanwhile, the electron-accepting property of oxazine ring in oxazine-modified fluoroquinolones (OFQs) increases emission peak at 498.0nm and decreases emission peak at 419.0nm as the color changes from blue to cyan. Moreover, a cascade system integrated with 3D microfluidic paper-based analytical device (3D-μPAD) is applied successfully for visually distinguishing three antibiotics, which shows great potential and versatility of M-GQDs for food safety monitoring.

C60 and Derivatives Boost Electrocatalysis and Photocatalysis: Electron Buffers to Heterojunctions

AbstractBuckminsterfullerene (C60) and derivatives are significant in the synthesis of efficient electrocatalysts and photocatalysts. This is because of electron acceptor properties and distinctive heterostructure(s) and physicochemical characteristics. High‐performance electrocatalysts and photocatalysts are important therefore in conversions for clean energy. Here a critical assessment of advances in use of C60 and derivatives as heterostructures and “electron buffers” in catalysts are reported. Methodologies for preparing C60 composite catalysts are assessed and categorized and microscopic mechanisms for boosting catalytic performance through C60 and derivatives in important catalytic materials including, semiconductors, carbon‐based metal‐free materials, metal nanoclusters, single atoms, and metal–organic skeletons are established. Important characterizations used with C60 and derivative composites are contrasted and assessed and practical challenges to development are determined. A prospective on future directions and likely outcomes in development of high efficiency electrocatalysts and photocatalysts is provided. It is concluded that C60 and derivatives are advantageous for advanced electrocatalysts and photocatalysts with high structural integrity and boosted electron transport. The findings are expected to be of interest and benefit to researchers and manufacturers for formation of heterostructures and electron buffer areas for significantly boosted catalytic performance.

Intramolecular nitrogen-sulfur interaction to enhance electron-accepting properties of end groups in small molecule donors

In organic solar cells (OSCs), it is very important to investigate the relationship between the structure and performance of materials by rational design of small molecule donors (SMDs). In this work, we use thiazole replace a thiophene unit in the π bridge, which could strengthen the connection between π bridges and end groups (EGs). Due to the N–S non-covalent interaction between EG and thiazole unit, the negative charge region of SMDs is expanded, the electron-withdrawing ability of EGs is also enhanced, and the corresponding molecular framework is twisted into a unique linear type. This can effectively enhance intermolecular interaction, promote molecular crystallization, and help to improve hole mobility of related SMDs. This work enriches design strategy that strengthens the interaction between π bridges and EGs, and provides a reference for studying the relationship between molecular structure and crystallinity.

Bio-based Au/g-CN plasmonic nanophotocatalyst for superior degradation of Rhodamine B under visible light illumination

Residual dyes on the earth’s surface are considered the most endangered and hazardous chemical waste, which severely contaminates the environment. Hence, systematic and strategic protocols should be carried out to degrade these dyes. The utilization of solar energy as the renewable energy carrier and semiconductor photocatalysts as the recyclable and sustainable catalyst for dye degradation is considered a promising method to monitor environmental remediation. Here we report a sustainable photocatalyst using room temperature-assisted green synthesis of hybrid plasmonic Au/g-CN photocatalyst using A. carambola leaf extract as a reducing as well as a stabilizing agent for Au nanoparticles (AuNPs) for degradation of RhB. The biomolecules present in the leaf extract reduce Au+3 to Au0 over the 2D surface of g-CN without using any toxic chemical-reducing agents. The structural, elemental, morphological, and optical properties of prepared nanocomposites are characterized by XRD, FTIR, XPS, TEM, HAADF-STEM, and PL techniques. The AuNPs successfully anchored on the surface of g-CN, having an average diameter of 25±1 nm. The photocatalytic degradation efficiency of 3Au/g-CN was found to be 99.4% for 10 ppm of RhB aqueous solution. The kinetics of the degradation were found to follow a pseudo-first-order reaction with a rate constant of 0.169 min−1. The photo-harvesting ability is enhanced by both the surface plasmon resonance (SPR) effect of Au and the electron-acceptor property of g-CN. Moreover, the 3Au/g-CN plasmonic composite was reusable up to 5 cycles.

From Terminal to Spiro-Phosphonium Acceptors, Remarkable Moieties to Develop Polyaromatic NIR Dyes.

Phosphonium-based compounds gain attention as a promising photofunctional materials. As a contribution to the emerging field, we present a series of donor-acceptor ionic dyes, which were constructed by tailoring the phosphonium (A) and extended π-NR2 (D) fragments to the anthracene framework. The alteration of the π-spacer of electron-donating substituents in species with terminal -+PPh2Me groups exhibits a long absorption wavelength up to λabs = 527 nm in dichloromethane and shifted the emission to the near-infrared (NIR) region (λ = 805 nm for thienyl aniline donor), although at low quantum yield (Φ < 0.01). In turn, the introduction of a P-heterocyclic acceptor substantially narrowed the optical bandgap and improved the efficiency of fluorescence. In particular, the phospha-spiro moiety allowed to attain NIR emission (797 nm in dichloromethane) with fluorescence efficiency of as high as Φ = 0.12. The electron-accepting property of phospha-spiro constituent outperformed that of the monocyclic and terminal phosphonium counterparts, illustrating a promising direction in the design of novel charge transfer chromophores.