Charge Transfer Interaction Research Articles

Novel NH4V4O10-Reduced Graphene Oxide Cathodes for Zinc-Ion Batteries: Theoretical Predictions and Experimental Validation

This investigation explores the potential of enhancing aqueous zinc-ion batteries (AZIBs) through the introduction of a novel cathode material, NH4V4O10 (NVO), combined with reduced graphene oxide (rGO). Utilizing Density Functional Theory (DFT), it was hypothesized that the incorporation of rGO would increase the interlayer spacing of NVO and diminish the charge transfer interactions, thus promoting enhanced diffusion of Zn2+ ions. These theoretical predictions were substantiated by experimental data acquired from hydrothermal synthesis, which indicated a marked increase in interlayer spacing. Significantly, the NVO–rGO composite exhibits remarkable cyclic durability, maintaining 95% of its initial specific capacity of 507 mAh g−1 after 600 cycles at a current density of 5 A g−1. The electrochemical performance of NVO–rGO not only surpasses that of pristine NVO but also outperforms the majority of existing vanadium oxide cathode materials reported in the literature. This study underscores the effective integration of theoretical insights and experimental validation, contributing to the advancement of high-performance energy storage technologies.

Electron Transfer Enhanced by a Minimal Energetic Driving Force at the Organic‐Semiconductor Interface

AbstractThe energetic driving force for electron transfer must be minimized to realize efficient optoelectronic devices including organic light‐emitting diodes (OLEDs) and organic photovoltaics (OPVs). Exploring the dynamics of a charge‐transfer (CT) state at an interface leads to a comprehension of the relationship between energetics, electron‐transfer efficiency, and device performance. Here, we investigate the electron transfer from the CT state to the triplet excited state (T1) in upconversion OLEDs with 45 material combinations. By analyzing the CT emission and the singlet excited‐state emission from triplet–triplet annihilation via the dark T1, their energetics and electron‐transfer efficiencies are extracted. We demonstrate that the CT→T1 electron transfer is enhanced by the stronger CT interaction and a minimal energetic driving force (<0.1 eV), which is explained using the Marcus theory with a small reorganization energy of <0.1 eV. Through our analysis, a novel donor–acceptor combination for the OLED is developed and shows an efficient blue emission with an extremely low turn‐on voltage of 1.57 V. This work provides a solution to control interfacial CT states for efficient optoelectronic devices without energy loss.

Electron Transfer Enhanced by a Minimal Energetic Driving Force at the Organic-Semiconductor Interface.

The energetic driving force for electron transfer must be minimized to realize efficient optoelectronic devices including organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs). Exploring the dynamics of a charge-transfer (CT) state at an interface leads to a comprehension of the relationship between energetics, electron-transfer efficiency, and device performance. Here, we investigate the electron transfer from the CT state to the triplet excited state (T1) in upconversion OLEDs with 45 material combinations. By analyzing the CT emission and the singlet excited-state emission from triplet-triplet annihilation via the dark T1, their energetics and electron-transfer efficiencies are extracted. We demonstrate that the CT→T1 electron transfer is enhanced by the stronger CT interaction and a minimal energetic driving force (<0.1 eV), which is explained using the Marcus theory with a small reorganization energy of <0.1 eV. Through our analysis, a novel donor-acceptor combination for the OLED is developed and shows an efficient blue emission with an extremely low turn-on voltage of 1.57 V. This work provides a solution to control interfacial CT states for efficient optoelectronic devices without energy loss.

Design of Charge Transfer Donor-Acceptor Co-Crystals with Long Lived Charge Carriers

Organic donor-acceptor co-crystals with long exciton lifetimes have emerged as a promising class of semiconductors for their unique photophysical properties. These are crystalline, single-phase materials composed of two or more different compounds in a stoichiometric ratio, providing a platform for unveiling the structure–property relationships at a molecular level. Importantly, co-crystals that are packed through π stacking interactions have the ability to form charge transfer (CT) excitons within donor-acceptor pairs.1,2,3 We hypothesize that co-crystals with a high degree of CT will have longer exciton lifetimes. Therefore, we design and synthesized of new co-crystals using derivatives of N,N-bis(3-pentyl)-perylene-3,4:9,10-bis(dicarboximide) (PDI, acceptor) with a series of donor molecules, including peri-xanthenoxanthene (PXX), perylene, and triphenylene. High quality single crystals were isolated by slow evaporation at room temperature from suitable solvent mixtures. Their crystal structures were successfully refined by single-crystal X-ray diffraction and the phase purity was validated by powder diffraction. Crystal structures revealed that the driving force for forming these co-crystals is π...π stacking. We measured diffuse reflectance UV/visible spectra of each of these co-crystals and compared with computed spectra to assign the observed electronic transitions. DFT calculations provide additional insights into the nature of the excited state CT interactions which can be derived from ground state electronic structure calculations. Transient absorption measurements were conducted to understand their long exciton lifetime for each of as synthesized co-crystals. We conclude that this study supported our previous hypothesis and such materials are potentially useful in applications ranging from photovoltaics and opto-electronics to photocatalysis. References 1) A. Abou Taka, J. E. Reynolds Iii, N. C. Cole-Filipiak, M. Shivanna, C. J. Yu, P. L. Feng, et al. Phys. Chem. Chem. Phys. 2023, 25, 27065.2) L. Sun, Y. Wang, F. Yang, X. Zhang and W. Hu. Adv. Mater. 2019, 31, 1902328.3) I. Schlesinger, N. E. Powers-Riggs, J. L. Logsdon, Y. Qi, S. A. Miller, R. Tempelaar, et al. Chem. Sci., 2020, 11, 9532–9541.

Supramolecular Assembly of Nitrogen-Containing Curved π-Conjugated Molecules to Polar Crystal

The chemistry of curved π-conjugated molecules has been extensively studied because of the development of their synthetic approach. Among the numerous studies, we have been engaged in nitrogen-containing curved π-conjugated molecules. These molecules have extended optical properties, redox-active behaviors, and electron-donating ability due to the electron-rich nature of nitrogen atoms. Recently, we have focused on the supramolecular assembling behavior of these compounds. For example, we have reported buckycatcher consisted of two azabuckybowls, providing two-photon absorbing host-guest complexes with fullerenes. In this presentation, we would like to show the packing behavior using π-extended azahelicenes and azabuckybowls. Our group has developed π-extended aza[5]helicene derivatives, showing brilliant emissive features. Recently, we succeeded in the synthesis of unsymmetrically substituted azahelicenes. We found that their stackings in the crystal were dependent on the substituent. X-ray diffraction analysis for all products showed π-stacked conformation with each other in the crystal (Figure 1b). In particular, azahelicenes with triisopropylsilyl groupswere found to align their dipole moments to form a one-dimensional columnar structure in the crystal. Polar crystals are expected to have applications in ferroelectric, piezoelectric, and nonlinear optical response materials. This is the first example of a polar crystal with helicenes, paving the way for novel piezoelectric organic materials.The second topic is related to azabuckybowl. In the crystal, azabuckybowl forms a face-to-face dimer by concave-convex interaction. In this study, we prepared two types of azabuckybowl perylene bisimide (PBI) dyads connected with alkyne linkages. PBIs have also been reported to show columnar stacking in solution. We anticipated that the segregate stacking should be achieved by recognizing the difference in structures between the bowl and planar geometry. The UV/vis absorption spectra revealed the presence of intramolecular charge-transfer interaction. In addition, the concentration-dependent absorption spectra and 1H NMR spectra indicated PBI and azabuckybowl units stacked with each other independently in solution (Figure 1a). Here, we would like to discuss about the effect of the effect of molecular shape on the supramolecular assembly with the data obtained using these compounds. Figure 1

Supramolecular Complex Surfactants and Structured Liquids Enabled by Cation-π and Charge-Transfer Interactions.

Cation-π and charge-transfer (CT) interactions are pervasive with significant implications in the fields of chemistry, materials science, and biology. However, much less is known about the construction of interfacial assemblies based on the two interactions. Here, by combining cation-π and CT interactions between an acceptor molecule, dicationic naphthalenediimide, and an aromatic donor, pyrene-terminated poly-l-lactic acid, we report the generation of supramolecular complex surfactants (SCSs) in situ at the toluene-water interface. The utilization of SCSs as building blocks enables the fabrication of interfacial assemblies including 2D films, emulsions, and structured liquids. By modification of the redox state of the acceptor molecules under chemical stimulus, the association/assembly and dissociation/disassembly of SCSs can be precisely regulated, imparting intriguing redox-responsive properties to the resulting assemblies.

Crystal structure, optical properties, Hirshfeld surface analysis and bactericidal activity of a new organic-inorganic hybrid: 4-methyl-1-(2'-nitrobenzyl)pyridinium tetrabromocuprate(II)

In this work, an organic-inorganic hybrid crystal with excellent bactericidal activity, 4-methyl-1-(2'-nitrobenzyl)pyridinium tetrabromocuprate(II) ([4Me2NO2BzPy]2[CuBr4]), was synthesized by the crystal growth by a slow evaporation method and characterized. [4Me2NO2BzPy]2[CuBr4] crystallized in the orthorhombic space group Pna21. Hirshfeld surface analysis indicated that the H···H (28.8%), H···Br/Br···H (27.0%), and O···H/H···O (17.5%) interatomic contacts played a primary role in contributing to the stacking of the crystals. Thermogravimetric analysis showed that the material was stable up to 192.5 °C. The charge transfer interaction between anions and cations was explained by UV-Vis diffuse reflectance spectroscopy. [4Me2NO2BzPy]2[CuBr4] exhibited favorable bactericidal activity against Staphylococcus aureus and Escherichia coli.

High electrical conductivity induced by charge transfer interactions in naphthalenediimide derivatives

Various studies have shown the influence of aliphatic, aromatic and bulky side chains on the optical, electrical conductivity and charge transport properties of naphthalenediimide (NDI) derivatives. The morphology, structural arrangement and the aggregation behaviour of these derivatives play an important role in influencing the charge transfer interactions between the donor and acceptor. These properties influence the electrical conductivity of the derivatives due to presence of charge transfer interactions. The present work focuses on the structure property relationship of the four NDI derivatives (SB-NDI) synthesized by imidization of dianhydride precursor with primary amine terminated Schiff bases (SB). The SB-NDI derivatives bear terminal phenyl ring attached to NDI through unsaturated or double unsaturated linkers bearing different electron withdrawing and donating groups. Among these, SB-NDI-2 derivative bearing –NO2 group in trans position at the terminal phenyl ring shows lowest –ΔGoET(CS) which allows favorable intramolecular charge separation. The Scanning electron microscopy shows ribbon like morphology for SB-NDI-2. The micron sized ribbons provide better charge transport and a conductivity of ∼1 Sm−1 at the room temperature without any additives. The special structure of SB-NDI provides charge transport properties allowing wide applications in the field of optoelectronics.

Combining the Fragment Molecular Orbital and GRID Approaches for the Prediction of Ligand-Metalloenzyme Binding Affinity: The Case Study of hCA II Inhibitors.

Polarization and charge-transfer interactions play an important role in ligand-receptor complexes containing metals, and only quantum mechanics methods can adequately describe their contribution to the binding energy. In this work, we selected a set of benzenesulfonamide ligands of human Carbonic Anhydrase II (hCA II)-an important druggable target containing a Zn2+ ion in the active site-as a case study to predict the binding free energy in metalloprotein-ligand complexes and designed specialized computational methods that combine the ab initio fragment molecular orbital (FMO) method and GRID approach. To reproduce the experimental binding free energy in these systems, we adopted a machine-learning approach, here named formula generator (FG), considering different FMO energy terms, the hydrophobic interaction energy (computed by GRID) and logP. The main advantage of the FG approach is that it can find nonlinear relations between the energy terms used to predict the binding free energy, explicitly showing their mathematical relation. This work showed the effectiveness of the FG approach, and therefore, it might represent an important tool for the development of new scoring functions. Indeed, our scoring function showed a high correlation with the experimental binding free energy (R2 = 0.76-0.95, RMSE = 0.34-0.18), revealing a nonlinear relation between energy terms and highlighting the relevant role played by hydrophobic contacts. These results, along with the FMO characterization of ligand-receptor interactions, represent important information to support the design of new and potent hCA II inhibitors.

Multi‐Resonance TADF Conjugated Polymers toward Highly Efficient Solution‐Processible Narrowband Green OLEDs

AbstractDue to the extended conjugation along the polymeric backbone and the scarcity of suitable multi‐resonance (MR) emitting units for polymerization, precisely adjusting the colors of MR‐thermally activated delayed fluorescence (MR‐TADF) conjugated polymers to green and red region remains to be a formidable challenge. Herein, this work develops a series of green MR‐TADF polymers for the first time by attaching MR emitting moiety as pendant to an acceptor triphenyltriazine while simultaneously embedding acceptor moiety into polycarbazole backbone. Benefitting from the enhanced intramolecular charge transfer (ICT) interaction by introducing acceptor on the para‐carbon position of boron (B) atom of the MR unit, as well as extended conjugation along backbone, all polymers exhibit red‐shifted emissions with emission peaks of 505–517 nm and full‐width at half maximums (FWHMs) of below 48 nm compared to the pendant bluish‐green MR unit peaking at 484 nm. The solution‐processed devices based on these polymers exhibit excellent performances with maximum quantum efficiency (EQE) of 22.2%, emission peak at 511 nm and FWHM of 44 nm, which represents the state‐of‐the‐art performance among the MR‐TADF polymer‐based narrowband OLEDs.

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This paper presents a novel macrocycle based on conformation‐adaptive and electron‐rich dihydrophenazine. The macrocycle exhibits host‐guest interaction with tetracyanoquinodimethane (TCNQ) driving by charge transfer interaction between them. The host‐guest complex forms stable radical cation species upon oxidation, resulting in the release of TCNQ from the macrocyclic cavity, thereby successfully achieving the reversible binding of guest molecules. More details are discussed in the article by Yang et al. on page 1895—1900.image

Interdisciplinary insights into (1′R,3S,3′R)-1'-(4-chlorobenzoyl)-5′,6′,7′,7a′-tetrahydro-1′H dispiro[indoline-3,2′-pyrrolizine-3′,3″-indoline]-2,2″-dione: Structural, electronic, and molecular dynamics perspectives

In the field of heterocyclic compounds, the spiro-pyrrolidine and oxindole ring systems are highly esteemed due to their distinctive structural scaffold that is present in numerous pharmacologically significant alkaloids. Interdisciplinary research has been increasingly important in recent years for deciphering the intricate characteristics and behaviors of novel organic compounds. The current work uses quantum chemical computational techniques to study the structural stability and nonlinear optical (NLO) activity of (1′R,3S,3′R)-1'-(4-chlorobenzoyl)-5′,6′,7′,7a′-tetrahydro-1′H dispiro[indoline-3,2′-pyrrolizine-3′,3″-indoline]-2,2″-dione (DSOIP-Cl). The study combines molecular biology, computational chemistry, and theoretical chemistry knowledge to create a comprehensive picture of this fascinating organic compound. This study employed the density functional theory (DFT) B3LYP method to compute the electronic properties and molecular geometry. The basis set for the computations was 6–311++G(d,p). The IEFPCM solvation method is used to investigate the behavior of the head compound in different solvents. Understanding the interaction between organic compounds and the solvent phase is crucial because the majority of interactions in biological systems occur in solution. UV–Vis spectral analysis of the molecule in different solvents is performed using the TD-DFT method. The compound exhibits more excellent absorption in polar solvents such as water, while its absorption is lower in the gaseous phase. Assessing NLO properties revealed optoelectronics applications. DSOIP-Cl has 5.25 times the first-order hyperpolarizability of urea. Different solvents have higher dipole moments and first-order hyperpolarizability than gases. To identify the inter- and intramolecular charge transfer interactions, intermolecular hydrogen bonding, and hyperconjugative interactions that stabilize the structure, natural bond orbital (NBO) analysis is performed. A stabilization energy of 9.99 kcal/mol is obtained for π(C32–C33) → σ*(C33–C34) due to strong intramolecular hyperconjugative interactions. Frontier molecular orbital (FMO) analysis helps determine the global reactivity parameters and the charge transfer interaction. The van der Waals interaction and steric effect within the molecule are identified using RDG analysis. The pharmacokinetic properties, adherence to drug-likeness criteria, and easily controllable synthesis process were evaluated through ADME analysis, establishing it as an up-and-coming candidate for subsequent drug development. Ultimately, to determine the biological activity and the ability of the title compound to inhibit aldose reductase, a series of computational techniques are employed, including molecular docking study, molecular dynamic (MD) simulation, and MM-PBSA binding energy calculations. −7.86 kcal/mol was reported as the docking score. Hydrophobic interactions play an essential role in the efficiency of protein-ligand binding. The remarkable energetic contribution of DSOIP-Cl to the MM-PBSA binding dynamics highlights its unique association with the AR protein, with a binding energy of −79.81 kJ/mol.

Mechanism Switch in Surface-Enhanced Raman Scattering: The Role of Nanoparticle Dimensions.

Surface-enhanced Raman scattering (SERS) is renowned for amplifying Raman signals, with electromagnetic mechanism (EM) enhancement arising from localized surface plasmon resonances and chemical mechanism (CM) enhancement as a result of charge transfer interactions. Despite the conventional emphasis on EM as a result of plasmonic effects, recent findings highlight the significance of CM when noble metals appear as smaller entities. However, the threshold size of the noble metal clusters/particles corresponding to the switch in SERS mechanisms is not clear at present. In this work, the VSe2-xOx/Au composites with different Au sizes are employed, in which a clear view of the SERS mechanism switch is observed at the Au size range of 16-21 nm. Our findings not only provide insight into the impact of noble metal size on SERS efficiency but also offer quantitative data to assist researchers in making informed judgments when analyzing SERS mechanisms.

White light-emissive triphenylamine-based triazole derivatives: Fluorescence switching response to volatile acid

Two triphenylamine-based tris and bis-triazole molecules (TTA and BTA) were reported, exhibiting significant fluorescence in the solid and solution states. TTA and BTA were highly sensitive towards trifluoroacetic acid (TFA) vapor by visible color change as the triazole nitrogen can easily be protonated. Triazoles show extreme sensitivity because of the reliable intramolecular charge transfer (ICT) interactions; the protonation of triazole moieties resulted in a bathochromic shift in UV–visible and fluorescence spectra. These spectra alterations were reversible when the base triethylamine (TEA) was added. When protonated, the fluorescence changed from blue to cyan, returning to blue on TEA addition (deprotonation). TTA displayed an Aggregation-Induced Enhanced Emission (AIEE) effect in the water: acetonitrile (7:3) combination. Density Functional Theory (DFT) calculations were utilized to calculate the energy gap between the HOMO-LUMO of TTA and BTA and their protonated forms. Both the triazoles were highly stable in a di-protonated state. Aside from acid sensitivity, TTA and BTA emitted white light with a high Color Rendering Index (CRI) of 87 % and 98 %, respectively, in the solid and the polymer composite thin film because of their multiple emission bands.

Quantum Computational and Spectroscopic Investigation of 3-aminosalicylic Acid.

Quantum chemical calculations of3-aminosalicylic acid (3ASA) (monomer and dimer forms) have been performed using DFT and TD-DFT theories with B3LYP/6-311 G(d,p) functional level in the ground and excited states. Using TD-DFT with IEF-PCM model, the electronic spectra of 3ASA in solvents were computed and correlated with the experimental data. The theoretically calculated absorption and emission maxima of 3ASA (monomer) are observed in the range of 343- 347nm (S0 → S1 transition) and 429- 448nm (S1 → S0 transition), respectively. The natural bond orbital (NBO) analysis shows that charge transfer interaction contributes significantly to stabilize the molecular system. In the case of dimer, hydrogen bonding plays a dominant role in stabilizing the molecular framework. Additionally, the obtained nonlinear optical (NLO) properties: polarizability (13.86 × 10-24 e.s.u for monomer and 29.46 × 10-24 e.s.u. for dimer), first-order hyperpolarizability (4.21 × 10-30 e.s.u for monomer and 0.18 × 10-30 e.s.u for dimer) and second-order hyperpolarizability (7.44 × 10-36 e.s.u. for monomer and 14.32 × 10-36 e.s.u. for dimer) were found to be larger than those of standard organic compounds suggesting that 3ASA has a significant NLO character for optoelectronic applications. The NLO properties of dimer may differ from monomer due to dimerization. Further, the radiative lifetime, light harvesting efficiency and band gap energy were calculated, and proposed that 3ASA may be useful in photovoltaics and wide bandgap power devices. HIGHLIGHTS: • DFT and TD-DFT theories were employed to calculate structural and molecular properties of 3ASA (monomer and dimer) in ground and excited states. • HOMO-LUMO study shows monomer and dimer of 3ASA are good reactive. • NBO analysis reflects that charge transfer interactions stabilized the 3ASA molecule. • Electronic absorption/emission spectra in solvents calculated by IEF-PCM/TD-DFT method correlate with experimental results. • Calculated NLO parameters suggested that 3ASA is a potential candidate for NLO material.

Charge transfer interaction dynamics between 6-Aminoindole and picric acid: Synthesis, spectrophotometric, characterization, computational, DNA binding, and anticancer properties

The charge transfer complex (CT) chemistry is studied between electron donor 6-Aminoindole (AMI) and electron acceptor Picric acid (PA) at 25 °C, in an acetonitrile medium by using UV–Visible absorption spectroscopy. The molecular ratio of the CT complex was determined to be 1:1 by using jobs variation and spectrophotometric titration processes. To assess the stability constant (KCT), and molar extinction coefficient (ƐCT) by using the Benesi-Hildebrand equation. These outcomes reveal that the synthesized CT complex is highly stable. The thermodynamic study is carried out in different temperatures (20-45 °C), and these results indicate increases the stability with increasing temperature. The CT complex structure was analyzed by FT-IR, 1H NMR, and 13C NMR. The surface morphology and elemental composition were identified by the SEM-EDX technique. The crystalline nature was analyzed by powdered XRD investigation. The CT complex has been screened for DNA binding and invitro cytotoxicity. The DNA binding constant value (2.3 × 105 M−1) and in vitro cytotoxicity test results on HeLa, suggest that it could be used as a potential medicinal drug in the future. Finally, the geometry optimizations were carried out by the DFT with the wB97XD method and 6-31+G(d,p) basis set. Here we investigated different parameters like bond parameters, NBO analysis, FMO analysis, DOS, PDOS, and computed electronic spectra. The computational analysis provided additional support for the experimental CT complex formation.

Transition Metal (Cu, Pd, and Ag)-Modified Nb2S2C Monolayer for Highly Efficient Catechol Sensing: A First-Principles Investigation.

Motivated by recent advancements and the escalating application of two-dimensional (2D) gas or molecule sensors, this study explores the potential of the 2D Nb2S2C monolayer for detecting biomolecule catechol (Cc), whose excess concentration is highly dangerous to living beings. We use first-principles density functional theory (DFT) calculations to assess the Cc sensing performance of pure and transition metal (TM = Cu, Pd, Ag)-modified Nb2S2C monolayers. The Nb2S2C monolayer belonging to the new class of synthesized 2D materials, TM carbo-chalcogenides (TMCC), combines distinctive properties from both TM dichalcogenides and TM carbides and exhibits physisorption (-0.66 eV) toward the Cc molecule. Notably, the surface modifications with these TMs significantly enhanced the adsorption energy of Cc. The chemisorption of the Cc molecule on the Pd to Cu-modified monolayer is demonstrated with adsorption energies ranging from -1.09 to -1.3 eV and is due to the robust charge transfer and orbital interactions between the valence orbitals of TMs and Cc. In addition, the modification of the surface by TM leads to an increased work function sensitivity toward the Cc molecule. The study establishes the thermal stability at 300 K and dynamic stability of TM-Nb2S2C through ab initio molecular dynamics (AIMD) simulations and Phonon calculations, respectively. The theoretical estimation of achievable recovery time at 400 and 450 K for Pd and Ag and at 500 K for the Cu-modified Nb2S2C monolayer, respectively, confirms the potential practical application of the sensor for Cc detection. These compelling characteristics position the Nb2S2C monolayer as a promising nanomaterial for detecting Cc molecules in the environment.

2D biphenylene-based nanostructures as prospective drug delivery carriers of carvedilol and levosim: DFT study

Drug delivery using 2D biphenylene-based nanostructures is investigated using DFT calculations. The explored nanostructures are energetically and dynamically stable with negative binding energies and real vibration frequencies. The high adsorption energy of ∼ -2.1 eV indicates the successful loading of the heart drugs (carvedilol and levosim). The chemical modification promotes adsorption by adding new adsorption sites at the edges. Surprisingly, no substantial change in the electronic structure following drug adsorption which is important for efficient drug release. Further analyses on natural charge and non-covalent interactions show noticeable charge transfer and non-covalent interactions between the drug and the biphenylene-based nanostructures.

Redox-Responsive Halogen Bonding as a Highly Selective Interaction for Electrochemical Separations.

Leveraging specific noncovalent interactions can broaden the mechanims for selective electrochemical separations beyond solely electrostatic interactions. Here, we explore redox-responsive halogen bonding (XB) for selective electrosorption in nonaqueous media, by taking advantage of directional interactions of XB alongisde a cooperative and synergistic ferrocene redox-center. We designed and evaluated a new redox-active XB donor polymer, poly(5-iodo-4-ferrocenyl-1-(4-vinylbenzyl)-1H-1,2,3-triazole) (P(FcTS-I)), for the electrochemically switchable binding and release of target organic and inorganic ions at a heterogeneous interface. Under applied potential, the oxidized ferrocene amplifies the halogen binding site, leading to significantly enhanced uptake and selectivity towards key inorganic and organic species, including chloride, bisulfate, and benzenesulfonate, compared to the open-circuit potential or the hydrogen bonding donor analog. Density functional theory calculations, as well as spectroscopic analysis, offer mechanistic insight into the degree of amplification of σ-holes at a molecular level, with selectivity modulated by charge transfer and dispersion interactions. Our work highlights the potential of XB in selective electrosorption by uniquely leveraging noncovalent interactions for redox-mediated electrochemical separations.

Molybdenum (VI) Complexes and their Dual Role as Antidiabetic and Anticancer Agents

AbstractTwo molybdenum complexes, MoHL1 and MoHL2, are prepared from the corresponding tetradentate salen type (ONNO) ligands, HL1 and HL2, obtained from 3, 5‐dichloro salicylaldehyde, and substituted o‐phenylenediamines. The complexes are characterized by 1H NMR, FTIR, HRMS, and UV‐visible spectral techniques. The DFT studies provide insight into their structural parameters. The band gap energy and molecular orbital energies influence the charge transfer interactions within the molecule. Further, the complexes are assessed for their antioxidant efficacy, α–amylase inhibitory potential, binding propensity with deoxyribonucleic acid, and cytotoxicity studies against breast cancer cell line, MCF7. The DPPH assay demonstrates high radical scavenging ability, as evidenced by the IC50 value of 133.85±1.18 μg/mL, higher than ascorbic acid. From the results of α–amylase inhibitory assay, MoHL1 shows good inhibitory action with the IC50 value of 32.72±2.49 μg/mL higher than that of the standard acarbose. The absorption titration method, to track the binding interactions of the metal complexes with DNA, shows a marked hyperchromic effect indicating preferential binding of the complexes to the grooves of DNA helical structure. MoHL2 exerts higher cytotoxicity against cancer cell lines than MoHL1. Thus, the complexes have the potential to be developed as antidiabetic and anticancer agents.