Aromatic Cations Research Articles

Chemically functionalized diamanes - A new class of hybrid 2D materials: DFT insight into crystal, mechanical, and electronic properties

This work describes crystal and electronic structures of a new class of 2D hybrid organic-inorganic compounds based on AB-stacked diamane. Seven members thereof are considered: methyl-, pyrrolyl-, 1,2,4-triazolyl-, phenyl-, pyridinyl-, and pyrimidinyl-substituted (two isomers) diamane. DFT calculations show that an electronic structure of diamane can be modulated by organic functional groups. The chemically functionalized diamanes are semiconductors with HSE06 electronic bandgaps falling in the range [2.09–4.91] eV. Other means of diamane electronic structure tuning include variation of coverage of a diamane surface by substituents, mixing of substituents and changing their mutual orientation. Based on the obtained results we conclude that the functionalized diamanes may serve as photovoltaic materials operable in Vis and near UV spectral regions. Owing to a similarity of the aromatics-substituted diamanes to low-dimensional hybrid metal halide perovskites with aromatic organic cations the former could be photoluminescent. An enhanced resistance of the investigated materials to water is expected.

Electrochemical Synthesis of C(sp3)-Rich Heterocycles via Mesolytic Cleavage of Anodically Generated Aromatic Radical Cations.

Herein we report an electrochemical deconstructive functionalization approach for the synthesis of C(sp3)-rich heterocycles. The reaction proceeds via the mesolytic cleavage of anodically generated aromatic radical cations and the trapping of formed carbocation intermediates with internal nucleophiles. The method has been demonstrated across various arylalcohol substrates to access a diverse range of C(sp3)-rich heterocycles including tetrahydrofuran, tetrahydropyran, and pyrrolidine scaffolds (26 examples). The electrochemical method was demonstrated on a 5 mmol scale via single pass continuous flow, which utilized lower supporting electrolyte concentration and exhibited increased productivity in relation to the batch process.

Electrochemical deconstructive functionalization of arylcycloalkanes via fragmentation of anodically generated aromatic radical cations.

This highlight summarises electrochemical approaches for the deconstructive functionalization of arylcycloalkanes via the fragmentation of anodically generated aromatic radical cations. A diverse range of deconstructive functionalization processes is described, including discussion on the electrochemical reaction conditions employed, scope and limitations, and reaction mechanisms, in addition to highlighting future opportunities in this burgeoning area of sustainable synthesis.

DFT insight into electronic structure of quasi 2D hybrid lead iodide perovskites with linear unsaturated diamines based on hexane

This work reports on electronic structures of hybrid quasi 2D lead iodide perovskites with linear unsaturated organic diamine cations containing six carbon atoms. Based on an actual structure of 1,6-diaminium lead iodide, a series of seven compounds with organic diamines ranging from 3-hexene-1,6-diamine to 1,3,5-hexatriyne-1,6-diamine was constructed. DFT calculations reveal domains in electronic structures of all the studied 2D compounds which are probably due to quantum-size effects. Electronic band structures of the considered species with π-conjugated organic cations possess flat unoccupied energy levels just like quasi low-dimensional hybrid metal halide perovskites with aromatic organic cations do. Energies of the flat unoccupied levels are tunable via electron-withdrawing/donating substituents at carbon-carbon double bonds. Owing to a similarity between the studied compounds with π-conjugated organic cations and quasi low-dimensional hybrid metal halide perovskites with aromatic organic cations the former are expected to be luminophores.

Positional Isomerism of Aromatic Heterocyclic Spacer Cations in Two-Dimensional Dion-Jacobson Hybrid Perovskites.

Ligand engineering of aromatic heterocyclic cations in two-dimensional (2D) Dion-Jacobson (DJ) perovskites has been widely explored in recent years. In this study, how the positional isomers of aromatic heterocyclic cations tune the lattice of 2D perovskites, thereby influencing the transport and recombination dynamics of charge carriers, has been investigated through nonadiabatic molecular dynamics simulations. We demonstrate that the meta-substituted 3-(aminomethyl)pyridinium (3AMPY) cations greatly reduce the strength of electron-vibration coupling since the strong hydrogen-bonding network introduced by the changes in the arrangement of spacer cations significantly suppresses the structural thermal fluctuations. Compared to the para-substituted 4-(aminomethyl)pyridinium (4AMPY) cation, using the asymmetric 3AMPY as a spacer cation can achieve improved in-plane transport performance, enhanced thermal stability, and suppressed charge carrier recombination through weakening electron-vibration interactions. Our results explain the observed lifetime difference between the two types of DJ-phase perovskites in experiments and provide new guidance for optimizing the performance of perovskite devices.

Unveiling the porosity effect of superbase ionic liquid-modified carbon sorbents in CO2 capture from air

Direct air capture (DAC) of CO2 represents one of the most promising technologies to achieve negative carbon emissions. In this work, the superbase ionic liquids (ILs)-modified carbon substrates were developed for DAC of CO2 by harnessing the strong CO2 binding capability of IL and the ordered porous channels of the carbon supports. Detailed porosity analysis revealed that the IL with an aromatic cation and an oxygenate anion preferred to fill the micropores, and a thin layer was created on the surface of the mesopores. Strong π-π interaction between the IL layer and the carbon surface was disclosed by wide-angle X-ray scattering (WAXS) analysis, leading to enhanced thermal stability of the IL phase. For the same lL coating amount, the DAC of CO2 evaluation revealed that a larger mesopore size and pore volume in the carbon/IL composite materials led to higher CO2 uptake capacity by exposing more active sites to integrate CO2 from diluted sources. The thermodynamic analysis confirmed the critical role of IL coating in providing strong chemisorption sites and significantly improved selectivity to enrich the diluted CO2 from the air atmosphere. This work provides guidance on leveraging the scaffolds' surface properties and porosities of the scaffolds to optimize DAC of CO2 behavior.

The robustness waterproof ionogel based on the phase separation to form soft hard heterostructures and the interaction of cation-π realizes underwater adhesion and sensing

Flexible ionic conductors hold significant promise for advancing the field of soft ion electronics in the future. However, the creation of flexible conductors that possess mechanical robustness, underwater adhesion and underwater motion monitoring remains a challenge. Drawing inspiration from the multiphase hetero structure found in biological connective tissues, such as high modulus fibers and low modulus water-rich matrices, this article proposes a one-pot polymerization in-situ design strategy to create a hydrophobic ionogel with a hetero structure of soft and hard domains. The mechanical robustness, elasticity, and toughness of the ionogel are achieved through a synergistic combination of a strong skeleton in the hard domain and an elastic matrix in the soft domain. Additionally,hydrophobic aromatic rings and quaternary ammonium cation simulated cation-π interactions in mussel foot silk protein. Upon contact with water, the hydrophobic clusters quickly aggregate, facilitating the expulsion of interfacial water and exposing salicylic acid groups and quaternary ammonium cationic groups, leading to outstanding underwater adhesion between the ionogel and various substrates. The resulting hydrophobic ionogel can be utilized in underwater wearable electronic devices for monitoring human movement and physiological information, underwater repair monitoring, and intelligent soft robotics, demonstrating its vast potential in the field of underwater sensors.

Unprecedented hybrid lead bromides featuring trivalent aromatic cation for potential photodetection

Organic cations, as charge compensators, balance the negative charge of lead halide anions through soft interaction forces, which have a significant impact on the crystal structure and electronic structure of hybrid lead halides. However, previous studies have mainly focused on monovalent and bivalent cations, and the use of trivalent cations in the synthesis and structure-activity relationship of hybrid lead halides has rarely been explored. Herein, two organic-inorganic hybrid lead bromines with trivalent aromatic cations were successfully synthesized, namely (H3tib)2Pb3Br12·H2O (1) and (H3tib)Pb2Br7 (2) (tib = 1, 3, 5-tri(1H-imidazol-1-yl)benzene). X-ray single-crystal diffraction techniques show that the crystal structures of 1 and 2 contain previously unreported (Pb3Br12)6− two-dimensional anion layer and (Pb2Br7)3− one-dimensional anionic chain, respectively. 1 is characterized by an indirect band gap with a band gap value of 3.04 eV, while 2 is characterized by a direct band gap with a value of 3.25 eV. The photocurrent switching ratio of 1 under visible light reaches 20.0, indicating its great potential in photodetection. Through Hirshfeld surface analysis and density functional theory (DFT) calculations, the electronic and band structure characteristics of the two compounds were discussed in depth.

Photocatalytic Decarboxylative Functionalization of Cyclopropenes via Cyclopropenium Cation Intermediates

AbstractA photocatalytic decarboxylative functionalization of cyclopropenes is reported. Starting from a broad range of redox‐active ester‐substituted cyclopropenes, cyclopropenylphthalimides can be synthesized in the absence of a nucleophile. Alternatively, different carbon and heteroatom nucleophiles can be introduced. The transformation proceeds most probably through the formation of an aromatic cyclopropenium cation, followed by trapping with the nucleophiles.

Photocatalytic Decarboxylative Functionalization of Cyclopropenes via Cyclopropenium Cation Intermediates.

A photocatalytic decarboxylative functionalization of cyclopropenes is reported. Starting from a broad range of redox-active ester-substituted cyclopropenes, cyclopropenylphthalimides can be synthesized in the absence of a nucleophile. Alternatively, different carbon and heteroatom nucleophiles can be introduced. The transformation proceeds most probably through the formation of an aromatic cyclopropenium cation, followed by trapping with the nucleophiles.

Improving the Water Resistance of Bi‐Based Perovskite‐Inspired Materials for Vapor‐Phase Photocatalytic Overall Water Splitting

Lead halide perovskites are well known for their exceptional photophysical and electronic properties, which have placed them at the forefront of challenging optoelectronic applications and solar‐to‐fuel conversion. However, their air/water instability, combined with their toxicity, is still a critical problem that has slowed down their commercialization. In this sense, bismuth‐based halide derivatives attract much interest as a potentially safer, air‐stable alternative. Herein, a novel Bi‐based perovskite‐inspired material, IEF‐19 (IEF stands for IMDEA Energy Framework), which contains a bulky aromatic cation (1,5‐diammonium naphthalene), is prepared. Additionally, an N‐alkylation strategy is successfully employed to achieve four water‐stable perovskite‐inspired materials, which contains diammonium naphthalene cations that are tetra‐alkylated by methyl, ethyl, propyl, and butyl groups. Moreover, computational studies are performed to gain a deeper understanding of the intrinsic structural stability and affinity of water molecules for Bi‐based perovskite‐inspired materials. Importantly, the air‐ and water‐stable IEF‐19‐Et (i.e., stable at least 12 months under ambient conditions and 3 weeks in contact with water) is found to be an active photocatalyst for vapor‐phase overall water splitting in the absence of any sacrificial agent under both ultraviolet–visible or simulated sunlight irradiation. This material exhibits an estimated apparent quantum yield of 0.08% at 400 nm, partially explained by its adequate energy band level diagram.

Regularities of Ion-Exchange Extraction of Anions 2(4)-Octylaminopyridines from Aqueous Media

Purpose of the study. Based on the results of the study of salts of 2(4)-octylaminopyridines (2(4)-OAP) by physical methods and their distribution in the two-phase system water-chloroform, establish the patterns of ion-exchange extraction of anions using aromatic amines.Methods. Chemical synthesis of 2(4)-OAP and their halides, spectrophotometry to determine the concentration of 2(4)-OAP in the aqueous and organic phase, characterization of 2(4)-OAP and their halides by IR, PMR and ESCA spectroscopy.Results. Synthesized by original methods and identified 2(4)-OAP and their halides. The distribution constants of 2-aminopyridine and 4-OAP salts with a singly charged anion in the water–chloroform two-phase system were determined. It is shown that the obtained constants increase in the following order: F-<Сl-<NO3-<Br-<ClO4-<SCN-<I-. In this case, a linear correlation between the logarithms of the constants and the hydration energy of anions in thisseries as a whole, which is typical for extraction with aliphatic amines and quaternary ammonium bases (FABs), is not observed. The results of the study of 2(4)-OAP halides by physical methods indicate a redistribution of the electron density in the aromatic cation depending on the nature of the anion, which ensures the selectivity of the extraction of “soft” (according to Pearson) 2(4)-OAP anions from aqueous media.Conclusion. The patterns of anion-exchange extraction of 2(4)-OAP, as well as, apparently, other aromatic amines, on the one hand, and aliphatic amines and PAO, on the other hand, coincide only with respect to “hard” anions. The situation changes during the extraction of "soft" anions. Due to the specificity of interionic interaction, aromatic amines are more selective with respect to "soft" anions, including, apparently, some acid complexes of "soft" metal cations, for example, with respect to halide complexes of platinum and other rare metals that are extracted by 2(4)-OAP better than by aliphatic amines and PAO.

Synthesis, physico-chemical properties and biological activity of 3-(aminophenyl)propionic and 2-amino-2-phenyl butyric acid hexafluosilicates

It is known that dental caries is a serious problem for the health care systems of most countries of the world, and the search for new effective and safe means of treatment and prevention of caries remains an urgent task of modern pharmaceutical science. At the same time, fluoride preparations remain the most effective and widely used in the modern arsenal of means for fighting caries. In recent years, ammonium hexafluorosilicates have been actively studied as potential caries preventive agents due to some advantages compared to traditional means of fluoride caries therapy. The aim of the work, which continues the earlier research of ammonium hexafluorosilicates with aromatic amino acid cations, is the synthesis, establishment of physicochemical properties and biological activity of 3-(3-aminophenyl)propionic, 3-(4-aminophenyl)propionic, 2-amino-2- phenylbutyric acid hexafluorosilicates as potential caries preventive agents. 3-(3-Aminophenyl)propionic, 3-(4-aminophenyl)propionic, 2-amino-2-phenylbutyric acid hexafluorosilicates (I–III, respectively) were synthesized in near-quantitative yields by reacting methanolic solutions of the corresponding amino acids with excess 45% silicon hydrofluoric acid. The isolated complexes were identified using the methods of elemental analysis, IR, NMR, 19F and mass spectroscopy. The solubility of I–III in water was established, which is 0.11–0.32 mol. %. The researched compounds I–III and reference drugs – NaF and (NH4)2SiF6 – were introduced into gels based on the Na-salt of carboxymethylcellulose, which were applied to the teeth and gums of rats. In an experiment on an experimental caries model, it was established that the caries preventive efficiency (СPE) of NaF, (NH4)2SiF6, I–III is 30.3%, 44.7%, 23.7%, 38.5%, 26.3%, respectively, that is, only the СPE of compound II exceeds the corresponding indicator for the reference preparation NaF by 1.27 times, while the СPE values of compounds I and III are inferior to both reference preparations. All studied fluoride preparations effectively normalize the biochemical indicators of dental pulp and homogenate of the oral mucosa of rats (phosphatase, elastase, urease and lysozyme activities, malondialdehyde level) that were on a cariogenic diet, and hexafluorosilicates in some cases are more effective compared to NaF.

Correlating π-π Stacking of Aromatic Diammoniums with Stability and Dimensional Reduction of Dion-Jacobson 2D Perovskites.

Dion-Jacobson (DJ) phase 2D perovskites with various aromatic diammonium cations, potentially possessing high stability, have been developed for optoelectronics. However, their stability does not meet initial expectations, and some of them even easily degrade into lower-dimensional structures. Underlying the stability mechanism and dimensional reduction of these DJ 2D perovskites remains elusive. Herein, we report that π-π stacking intensity between aromatic cations determines structural stability and dimensional variation of DJ 2D perovskites by investigating nine benzene diammoniums (BDAs)-derived low-dimensional perovskites. The BDAs without intermolecular π-π stacking form stable DJ 2D perovskites, while those showing strong π-π stacking tend to generate 1D and 0D architectures. Furthermore, the π-π stacking intensity highly relies on molecular symmetry and electrostatic potential of BDAs; namely, asymmetry and small dipole moment facilitate alleviating the π-π stacking, leading to the formation of DJ 2D perovskites and vice versa. Our findings establish the relationship of aromatic diammonium structure-π-π stacking interaction-perovskite dimensionality, which can guide the design of stable DJ 2D perovskites and the manipulation of perovskite dimensionality for various optoelectronic applications.

Functionalized Ionic Liquids as Asphaltene Dispersants: A Comparison between Aliphatic and Aromatic Cations

Functionalized Ionic Liquids as Asphaltene Dispersants: A Comparison between Aliphatic and Aromatic Cations

Structure Directing Forces in Hybrid Layered Double Perovskites Containing Aromatic Organic Cations

Structure Directing Forces in Hybrid Layered Double Perovskites Containing Aromatic Organic Cations

Synthesis and Properties of Azahomocorannulenyl Cations and Radicals

AbstractCycloheptatrienyl (tropyl) molecules are representative non‐alternant hydrocarbons that offer interesting chemistry because of their unique structures and properties. However, there have been a limited number of polycyclic aromatic tropyl cations and radicals reported in the literature. Herein, we report the synthesis of a series of azahomocorannulene derivatives, where the key reactions are a 1,3‐dipolar cycloaddition of polycyclic aromatic azomethine ylides with dibenzotropone and a subsequent palladium‐catalyzed cyclization. X‐ray diffraction analysis revealed that the obtained azahomocorannulenyl cation and radical adopt planar structures and exhibit unique packing structures. Their electronic and optical properties were investigated experimentally and theoretically to reveal their aromatic character.

Synthesis and Properties of Azahomocorannulenyl Cations and Radicals.

Cycloheptatrienyl (tropyl) molecules are representative non-alternant hydrocarbons that offer interesting chemistry because of their unique structures and properties. However, there have been a limited number of polycyclic aromatic tropyl cations and radicals reported in the literature. Herein, we report the synthesis of a series of azahomocorannulene derivatives, where the key reactions are a 1,3-dipolar cycloaddition of polycyclic aromatic azomethine ylides with dibenzotropone and a subsequent palladium-catalyzed cyclization. X-ray diffraction analysis revealed that the obtained azahomocorannulenyl cation and radical adopt planar structures and exhibit unique packing structures. Their electronic and optical properties were investigated experimentally and theoretically to reveal their aromatic character.

Surface-assisted synthesis of perovskite nanosheets with bivalent aromatic cations

Halide perovskites have attracted significant attention as cutting-edge semiconducting materials, particularly as ultrathin layers for optoelectronic applications.

Deciphering the role of aromatic cations in electrochemical CO2 reduction: interfacial ion assembly governs reaction pathways

Imidazolium cations facilitate electrochemical CO2 reduction by (1) stabilizing CO2˙− with delocalized positive charge (π+) and (2) tuning the transport of proton donors to the electrochemical interface.