Aromatic Organic Molecules Research Articles

Toward the identification of cyano-astroCOMs via vibrational features: benzonitrile as a test case.

The James Webb Space Telescope (JWST) opened a new era for the identification of molecular systems in the interstellar medium (ISM) by vibrational features. One group of molecules of increasing interest is cyano-derivatives of aromatic organic molecules, which have already been identified in the ISM on the basis of the analysis of rotational signatures, and so, are plausible candidates for the detection by the JWST. Benzonitrile considered in this work represents a suitable example for the validation of a computational strategy, which can be further applied for different, larger, and not-yet observed molecules. For this purpose, anharmonic simulations of infrared (IR) spectra have been compared with recent FTIR experimental studies. The anharmonic computations using the generalized second-order vibrational perturbation theory (GVPT2) in conjunction with a hybrid force field combining the harmonic part of revDSD-PBEP86-D3/jun-cc-pVTZ with anharmonic corrections from B3LYP-D3/SNSD show very good agreement with those in the experiment, with a mean error of for all fundamental transitions overall and only for the stretching fundamental at 4.49 . The inclusion of overtones up to three-quanta transitions also allowed the prediction of spectra in the near-infrared region, which shows distinct features due to overtones at the 2.26 and 1.52 . The remarkable accuracy of the GVPT2 results opens a pathway for the reliable prediction of spectra for a broader range of cyano-astroCOMs.

Cucurbit[8]uril-modulated discrete pyrene dimers fluorescent sensor for nitroaromatic compounds and latent fingerprints visualization

As a promising class of luminescent materials, π-conjugated organic aromatic molecules are usually subject to aggregation-caused quenching (ACQ) effect, which limits their wide application. Currently, obtaining structurally visualized solid luminescent materials of polycyclic aromatic hydrocarbons (PAHs) without complex synthetic purification steps remains a challenging topic. Herein, we focus on the supramolecular assembly strategy to constructed a solid fluorescent material (HPTS@Q[8]@Rb+) by co-assembling cucurbit[8]uril (Q[8]) with 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) and rubidium ions based on the coordination and outer surface interactions of Q[8]. HPTS@Q[8]@Rb+ exhibited good fluorescence properties with quantum yields of 2.28 % and 73.15 % in solid state and aqueous suspensions, respectively, providing a good sensing platform for nitroaromatic compounds (NACs), especially for 2,4,6-trinitrophenol (PA) and 4-nitroaniline (4-NA) with remarkable quenching constants (KSV=4.06×104 M−1 for PA and KSV=2.95×104 M−1 for 4-NA) in working range of 0–3.33×104 M and 0–5.0×104 M, respectively. Moreover, a fluorescent fingerprint powder was prepared by combining montmorillonite (MMT) for high-resolution visualization of latent fingerprints (LFPs) without substrate limitation. This study demonstrates the synthesis of Q[n]-based fluorescent material, the anion-rich aromatic compounds can be used as potential moieties for assembly with Q[n], providing a facile and promising approach to develop PAHs-based luminescent materials. This supramolecular self-assembly strategy provides a fundamental design principle for the creation of diverse functional crystalline solid materials.

A new non-centrosymmetric material (C5H9N3)[ZnBr4]·H2O : Molecular structure, characterization, optical properties and biological activities

The use of 2,3-diaminopyridine as an aromatic organic molecule in the synthesis of a new hybrid halogenometallate compound by the slow evaporation method afforded an unexpected non-centrosymmetric structure type. The obtained material with the formula (C5H9N3)[ZnBr4]·H2O (1) crystallizes in the triclinic space group P1. The compound was characterized by UV–visible measurements, differential thermal analysis (TG-DTA), single crystal X-ray diffraction and nonlinear optical activity. The structure consists of isolated tetrahedral [ZnBr4]2− anions, 2-amino-3-ammoniopyridinium [C5H9N3]2+ cations and water molecules, which are connected via NH…O/Br and OH…Br hydrogen bonds leading to the formation and strengthening of a three-dimensional supramolecular assembly. The optical band gap and Urbach energy were obtained through Tauc's equation. The direct and indirect band gap values are found to be 3.23 and 3.55 eV, respectively. The bioassay results showed that the compound exhibits modest antibacterial and antifungal activities.

Metabolic versatility of soil microbial communities below the rocks of the hyperarid Dalangtan Playa.

The hyperarid Dalangtan Playa in the western Qaidam Basin, northwestern China, is a unique terrestrial analog of Mars. Despite the polyextreme environments of this area, habitats below translucent rocks capable of environmental buffering could serve as refuges for microbial life. In this study, the hybrid assembly of Illumina short reads and Nanopore long reads recovered high-quality and high-continuity genomes, allowing for high-accuracy analysis and a deeper understanding of extremophiles in the sheltered soils of the Dalangtan Playa. Our findings reveal self-supporting and metabolically versatile sheltered soil communities adapted to a hyperarid and hypersaline playa, which provides implications for the search for life signals on Mars.

Diverse organic-mineral associations in Jezero crater, Mars

The presence and distribution of preserved organic matter on the surface of Mars can provide key information about the Martian carbon cycle and the potential of the planet to host life throughout its history. Several types of organic molecules have been previously detected in Martian meteorites1 and at Gale crater, Mars2–4. Evaluating the diversity and detectability of organic matter elsewhere on Mars is important for understanding the extent and diversity of Martian surface processes and the potential availability of carbon sources1,5,6. Here we report the detection of Raman and fluorescence spectra consistent with several species of aromatic organic molecules in the Máaz and Séítah formations within the Crater Floor sequences of Jezero crater, Mars. We report specific fluorescence-mineral associations consistent with many classes of organic molecules occurring in different spatial patterns within these compositionally distinct formations, potentially indicating different fates of carbon across environments. Our findings suggest there may be a diversity of aromatic molecules prevalent on the Martian surface, and these materials persist despite exposure to surface conditions. These potential organic molecules are largely found within minerals linked to aqueous processes, indicating that these processes may have had a key role in organic synthesis, transport or preservation.

A π-π Bonding-Assisted Molecular-Wiring of Folded-Cytochrome c and Naphthoquinone and Its Electron-Relay-Based Bioelectrocatalytic H2O2 Reduction Reaction Visualized by Redox-Competitive Scanning Electrochemical Microscopy.

The electron-transfer (ET) reaction of cytochrome c (Cytc) protein with biomolecules is a cutting-edge research area of interest in understanding the functionalities of natural systems. Several electrochemical biomimicking studies based on Cytc-protein-modified electrodes prepared via electrostatic interaction and covalent bonding approaches have been reported. Indeed, natural enzymes involve multiple types of bonding, such as hydrogen, ionic, covalent, and π-π, etc. In this work, we explore a Cytc-protein chemically modified glassy carbon electrode (GCE/CB@NQ/Cytc) prepared via π-π bonding using graphitic carbon as an underlying surface and an aromatic organic molecule, naphthoquinone (NQ), as a cofactor for an effective ET reaction. A simple drop-casting technique-based preparation of GCE/CB@NQ showed a distinct surface-confined redox peak at a standard electrode potential (E°) = -0.2 V vs Ag/AgCl (surface excess = 21.3 nmol cm-2) in pH 7 phosphate buffer solution. A control experiment of modification of NQ on an unmodified GCE failed to show any such unique feature. For the preparation of GCE/CB@NQ/Cytc, a dilute solution of Cytc-pH 7 phosphate buffer was drop-cast on the GCE/CB@NQ surface, wherein the protein folding and denaturalization-based complication and its associated ET functionalities were avoided. Molecular dynamics simulation studies show the complexation of NQ with Cytc at the protein binding sites. The protein-bound surface shows an efficient and selective bioelectrocatalytic reduction performance of H2O2, as demonstrated using cyclic voltammetry and amperometric i-t techniques. Finally, the redox-competition scanning electrochemical microscopy (RC-SECM) technique was adopted for in situ visualization of the electroactive adsorbed surface. The RC-SECM images clearly show the regions of highly bioelectrocatalytic active sites of Cytc-proteins bound to NQ molecules on a graphitic carbon surface. The binding of Cytc with NQ has significant implications for studying the biological electron transport mechanism, and the proposed method provides the requisite framework for such a study.

The Boost of Toluene Capture in UiO-66 Triggered by Structural Defects or Air Humidity.

This work aimed to investigate the adsorption of toluene in UiO-66 materials. Toluene is a volatile, aromatic organic molecule that is recognized as the main component of VOCs. These compounds are harmful to the environment as well as to living organisms. One of the materials that allows the capture of toluene is the UiO-66. A satisfactory representation of the calculated isotherm steep front and sorption capacity compared to the experiment was obtained by reducing the force field σ parameter by 5% and increasing ε by 5%. Average occupation profiles, which are projections of the positions of molecules during pressure increase, as well as RDFs, which are designed to determine the distance of the center of mass of the toluene molecule from organic linkers and metal clusters, respectively, made it possible to explain the mechanism of toluene adsorption on the UiO-66 material.

Quasi-Reversible Photoinduced Displacement of Aromatic Ligands from Semiconductor Nanocrystals.

Organic-inorganic nanohybrids using semiconductor nanocrystals (NCs) coordinated with aromatic organic molecules have been widely studied in the fields of optoelectronic materials, such as solar cells, photocatalysis, and photon upconversion. In these materials, coordination bonds of ligand molecules are usually assumed to be stable during optical processes. However, this assumption is not always valid. In this study, we demonstrate that the coordination bonds between ligand molecules and NCs by carboxyl groups are displaced quasi-reversibly by light irradiation using zinc sulfide (ZnS) NCs coordinated with perylenebisimide (PBI) as a model system. Time-resolved spectroscopy over a wide range of time from tens-of femtosecond to second timescales and density functional theory calculations show that the photoinduced ligand displacement is driven by ultrafast hole transfer from PBI to ZnS NCs and that the dissociated radical anion of PBI survives over the second timescale. Photoinduced ligand displacements are important to be considered in various organic-inorganic nanohybrids and offer a possibility of NCs covered by nonphotoresponsive organic ligands for advanced photofunctional materials.

Exploiting the Coordination Effect in Fe-Phenanthroline Complex for the Catalytic Carbonization of Phenanthroline toward the High Capacity Anode Grade Carbon

Aromatic organic molecules (AOMs) present an appealing precursor option for anode-grade hard carbon for sodium-ion batteries (SIBs) because of their prevalence, diverse chemical functionalities, and huge scope for nanostructure engineering at the molecular level. However, most small organic molecules decompose before actual carbonization is initiated unless reactions are carried out under high pressures or in the presence of catalysts. Herein, we report a facile carbonization of aromatic monomeric phenanthroline (phen) by exploiting the strong molecule-level coordination effect of the Fe-phen complex and in situ catalysis affected by Fe. With this carbonization strategy, we achieve better scalability with appreciable carbon yield, while carbonization of simple phen molecule returns zero carbon yields. The as-prepared N-doped microporous carbon (NMC) possesses desirable microstructural features with optimum nitrogen content to be employed as an anode for SIB. As an anode, the NMC delivers a high reversible capacity of 271 mAh g–1 at 100 mA g–1, an ultrahigh rate capability of 101 mAh g–1 at 1 A g–1, and a stable cycle life. The galvanostatic intermittent titration technique (GITT) depicts sodium ion diffusion coefficients of the order of ∼10–13 (cm2 s–1) in the intercalation region, which implies a faster sodium ion diffusion rate compared to most of the reported hard carbons. Given the vast diversity of AOMs, this work encourages new research interests to produce advanced carbon materials with nanostructure engineering at the molecular level for sodium-ion battery applications.

Assessment of the oxidative damage and apoptotic pathway related to furan cytotoxicity in cultured mouse Leydig cells.

Research on heat-induced food contamination is being given more attention as a result of the health risks that have been publicly revealed in recent years. Furan is known as a colorless, combustible, heterocyclic aromatic organic molecule and is formed when food products are processed and stored. It has been established that furan, which is inevitably ingested, has a deleterious impact on human health and causes toxicity. Furan is known to have adverse effects on the immune system, neurological system, skin, liver, kidney, and fat tissue. Infertility caused by furan is a result of its damaging effects on several tissues and organs as well as the reproductive system. Although studies on the adverse effects of furan on the male reproductive system have been performed, there is no study revealing apoptosis in Leydig cells at the gene level. In this study, TM3 mouse Leydig cells were exposed to 250- and 2,500-μM concentrations of furan for 24h. The findings demonstrated that furan decreased cell viability and antioxidant enzyme activity while increasing lipid peroxidation, reactive oxygen species, and apoptotic cell rates. Furan also increased the expression of the important apoptotic genes Casp3 and Trp53 while decreasing the expression of another pro-apoptotic gene, Bcl2, and antioxidant genes Sod1, Gpx1, and Cat. In conclusion, these results imply that furan may cause loss of cell function in mouse Leydig cells responsible for testosterone biosynthesis by impairing the efficiency of the antioxidant system, possibly by inducing cytotoxicity, oxidative stress, and apoptosis.

Including vibrational effects in magnetic circular dichroism spectrum calculations in the framework of excited state dynamics.

In this work, we present a computational approach that is able to incorporate vibrational effects in the computations of magnetic circular dichroism (MCD) spectra. The method combines our previous implementations to model absorption as well as fluorescence and phosphorescence spectra in the framework of excited state dynamics with a new technique to calculate MCD intensities, where molecular orientational averages are treated via semi-numerical quadrature. The implementation relies on a path integral approach that is employed to compute nuclear dynamics under the harmonic oscillator approximation (accounting for the nuclear potential energy surface) together with quasi-degenerate perturbative theory (to include the perturbation of an external magnetic field). We evaluate our implementation with a selected molecular set consisting of five aromatic organic molecules, namely, 1,4-benzoquinone, naphthalene, 2-naphthylamine, 2-naphthaldehyde, and benzene; we also included the MnO4- and the [Co(NH3)6]3+ transition metal complexes. This set is used to validate the ability of the approach to compute MCD A- and B-terms in conjunction with time-dependent density functional theory. The computed intensities are discussed in terms of the overall quality of the electronic structure treatments, vibrational modes, and the quality of the nuclear Hessians. It is shown that in the cases in which the potential energy surface is accurately represented, electric dipole-forbidden transitions are vibrationally activated, producing intensities relative to the dipole-allowed transitions in the same order of magnitude as the experimental measurements.

Adsorption Studies at the Graphene Oxide-Liquid Interface: A Molecular Dynamics Study.

The adsorption of organic aromatic molecules, namely aniline, onto graphene oxide is investigated using molecular simulations. The effect of the oxidation level of the graphene oxide sheet as well as the presence of two different halide salts, sodium chloride and sodium iodide, were examined. The aniline molecule in the more-reduced graphene oxide case, in the absence of added salt, showed a slightly greater affinity for the graphene oxide-water interface as compared to the oxidized form. The presence of the iodide ion increased the affinity of the aniline molecule in the reduced case but had the opposite effect for the more-oxidized form. The effect of oxidation and added salt on the interfacial water layer was also examined.

Design of Porous Graphene Materials from Organic Precursors

AbstractThe preparation of the porous graphene materials with controllable porosity basically depends on the design of porous architectures. The development of three‐dimensional (3D) graphene materials from two‐dimensional (2D) graphene sheets can harness the unique physical and electrical properties of graphene, but the challenges lie on the design and synthesis of nanoporous graphene with controlled engineering. In this work, two organic aromatic molecules viz., 2‐amino‐3‐hydroxypyridine and phloroglucinol were targeted for the development of porous graphene nanostructures. The synthesis process was designed in such a way that both the molecules having ─OH and ─NH2 groups at ortho position and 3 ─OH groups at 1, 3, 5 positions, respectively, can generate pores along with the development of graphenic lattice during heat treatment. The optimization of reaction conditions viz., time and temperature was done and the chemistry of formation of porous natured graphenic lattice was discussed. Interestingly, the results indicate that both the organic molecules have the potential to develop porous graphenic structures within their lattice at relatively low temperatures without using any additional reagents and reaction conditions. It is suggested that the structure of organic precursor is a critical factor which needs to be optimized to produce porous graphenes.

Dynamics of Site Selectivity in Dissociative Electron Attachment in Aromatic Molecules

Dissociative electron attachment has shown site selectivity in aliphatic molecules based on the functional groups present in them. This selectivity arises from the core excited resonances that have excited parent states localized to a specific site of the functional group. Here, we show that such site selectivity is also observed in the amine group when present in aromatic molecules. However, the proximity of the aromatic ring to the functional group under investigation has a substantial effect on the dissociation dynamics. This effect is evident in the momentum distribution of the hydride ions generated from the amine group. Our results unravel the hitherto unknown facets of the site selectivity in aromatic organic molecules.

Successful removal of phenol from industrial wastewater using novel hydrophobic modified ceramic hollow fiber membrane contactors with remarkably high stability

Wastewater pollution has become a serious global issue in recent years. One of the most prevalent industrial wastewater contaminants is phenol, a hazardous aromatic organic molecule. Part of the answer is to promote novel technologies for reducing the quantity of phenol (PH) in industrial wastewater. The liquid–liquid (LL) PH extraction process through a hydrophobically modified ceramic (Al2O3) hollow fiber (Al2O3HF) membrane contactor from an aqueous solution with a high initial concentration of PH (3500 ppm) was studied for the first time. Al2O3HF membranes were prepared by a combined phase-inversion and sintering process. All membranes were fully characterized. PH extraction process tests were performed at a temperature range from room temperature to 50 °C. Under room temperature conditions, the total PH extraction (%) was 80 % with respect to the initial PH concentration. The total PH extraction (%) increases as the temperature increases, reaching a value of about 91 % at 50 °C. The durability of the Al2O3HF membrane contactor during a long-term LL PH extraction was investigated at 40 °C. The Al2O3HF membrane contactor exhibited no degradation in LL PH removal ability after a 100-hour LL PH extraction operation.

Enhancement of power conversion efficiency of dye-sensitized solar cell via symmetrical Bi-anchoring organic molecules as co-sensitizer

A strategy has carried to improvise the photovoltaic performance of DSSCs using auxiliary compounds as co-sensitizer along with organic sensitizer. Herein, bi-anchoring metal-free aromatic organic molecules (A-π-A) based co-sensitizer was utilized with organic sensitizer (DTTCY) and a Co 2+/3+ [bnbip] redox couple incorporated PEG-HEC quasi-solid-state electrolyte for an efficient DSSCs. Interestingly, ACY organic co-sensitized device (typically TiO 2 /ACY/DTTCY/Co 2+/3+ [bnbip]/PEG-HEC/Pt) has achieved a maximum power conversion efficiency of 8.3% under AM 1.5 G illumination (100 mW cm −2 ). At the same instance, NCY and PCY co-sensitized devices achieved comparably lower PCE of 7.44% and 6.99% respectively. These results prove that longer π-conjugation and bi-anchoring group of ACY molecules has induced electron injection process on TiO 2 surface. The influences of co-sensitizer are strongly covered the naked spectrum in the UV region and fill the vacant area in TiO 2 that induces a change in Quasi Fermi level of and decreases recombination flanked by photo-anode and oxidized cobalt species. The PCE results of ACY sensitized device are sustained by some electrochemical factors such as Bulk Resistance (R s = 17.23 Ω), Recombination Resistance (R Rec = 18.84 Ω), Charge Transfer Resistance (R CT = 1.136 Ω), Chemical capacitance (C μ = 13.66 μF), Ionic Conductivity (σ = 2.31 E −03 S cm −1 ), electron lifetime (τ n = 52.85 μs), electron transport time (τ d = 3.29.\μs) and collection efficiency (η COL = 93.97 %), rate of reaction constant (K eff = 18.92 s −1 ), Electron Density (n s = 1.21 E +17 cm −3 ), Dielectric constant (D eff = 0.011 mm 2 s -1 ), Dielectric Length (L n = 0.776 mm). The opportunity of trapping the co-sensitizer system functionalizes the anode surface supposed to avoid back electron transfer and dye degradation. The motive of the study is to enhance the photo-ability of metal-free DTTCY sensitizer along with metal-free co-sensitizer and metal-free additives integrated into the blend polymer electrolyte. • Design and synthesis of (A-π-A) based co-sensitizer for DSSCs application. • PEG-HEC polymer with Cobalt redox couple used as an effective QSS electrolyte. • ACY organic co-sensitized device has achieved a maximum PCE of 8.3%. • ACY co-sensitizer reduces recombination reaction in DSSCs.

Preparation and characterization of non-aromatic ether self-assemblies on a HOPG surface

On-surface self-assemblies of aromatic organic molecules have been widely investigated, but the characterization of analogous self-assemblies consisting of fully sp3-hybridized molecules remains challenging. The possible on-surface orientations of alkyl molecules not exclusively comprised of long alkyl chains are difficult to distinguish because of their inherently low symmetry and non-planar nature. Here, we present a detailed study of diamondoid ethers, structurally rigid and fully saturated molecules, which form uniform 2D monolayers on a highly oriented pyrolytic graphite (HOPG) surface. Using scanning tunneling microscopy, various computational tools, and x-ray structural analysis, we identified the most favorable on-surface orientations of these rigid ethers and accounted for the forces driving the self-organization process. The influence of the oxygen atom and London dispersion interactions were found to be responsible for the formation of the observed highly ordered 2D ether assemblies. Our findings provide insight into the on-surface properties and behavior of non-aromatic organic compounds and broaden our understanding of the phenomena characteristic of monolayers consisting of non-planar molecules.

Crystal structure and photoluminescence properties of a supramolecular hybrid bisulfate and hydrogenphosphate salts

The use of 4-pyridinethioamide as an aromatic organic molecule in the synthesis of two hybrid bisulfate and hydrogenphosphate salts by slow evaporation method provided a supramolecular structure type. The obtained materials with formula [C6H7N2S][HSO4] and [C6H7N2S][H2PO4] crystallize according to the triclinic symmetry with the space group P1¯ and to the monoclinic symmetry with the space group P21/c, respectively. The mineral part is built from bisulfate [HSO4]− or hydrogenphosphate [H2PO4]− ions linked together and to the organic [C6H7N2S]+ cations by hydrogen bonds only. The Hirshfeld analysis results shows that in all potential molecular contacts, the H···O/O···H constitutes the most important interaction in the crystal (47.1 and 30.9%). The thermal behavior studied by thermogravimetric analyses shows a good stability up to 150 °C. Photoluminescence measurement indicates that material with formula [C6H7N2S][HSO4] manifests blue luminescence while the material [C6H7N2S][H2PO4] manifests green luminescence, both in their solide states.

Outside Front Cover: Plasma Process. Polym. 3/2022

Outside Front Cover: The mechanism of formation of Reactive Nitrogen Species (RNS) and Reactive Oxygen Species (ROS) in Plasma Treated Water Solutions (PTWS) is far from being understood. In this paper, we demonstrate how the different composition of the liquids affects the chemical composition of PTWS. Aromatic organic molecules play an active role in the production of ROS (i.e. H2O2). Further details can be found in the article by Valeria Veronico, Pietro Favia, Francesco Fracassi, Roberto Gristina, and Eloisa Sardella (e2100158)

Porous Au/γ-AlOOH Nanoflowers for Surface-Enhanced Raman Scattering Detection of Aromatic Acid Compounds

γ-AlOOH with abundant dangling hydroxyl groups and plasmonic Au catalyst was used to synthesize porous Au/γ-AlOOH nanoflowers. Synergistic electromagnetic field mechanism (EM) and efficient charge transfer (CT) could be expected to be achieved by the Au and γ-AlOOH nanocomposites to provide a higher concentration of Lewis-type basic sites for the monodentate coordination of aromatic acid compounds and highly sensitive detection via surface-enhanced Raman scattering (SERS) spectroscopy. This material had excellent conductivity, reducing electron and hole recombination and accelerating charge transport, improving charge utilization, and exhibited remarkable stability as well as repeatability as a SERS substrate. This strategy is expected to be recognized as a nanostructured catalyst used for organic aromatic molecules with no steric hindrance in bidentate coordination with the most effective chemical enhancement mechanism (CM) effect.