Catechol Molecules Research Articles

Nano-structured urchin-like photothermal covalent organic frameworks for efficient Solar-Driven interfacial water evaporation

Solar-driven interfacial water evaporation is a promising sustainable technology to alleviate the global energy crisis and clean water shortage. The design of advanced photothermal materials play the critical role to utilize photothermal heat for water evaporation. Covalent organic frameworks (COFs) as a new class of crystalline porous polymer semiconductor materials have been deemed as an ideal nanoscale platform for designing photothermal materials with notable features like highly ordered structures, porous open channels, and tunable structure and functionality. In this work, we focus on the regulation of the multi-scale structure of COFs and design hierarchically nano-structured photothermal COFs for efficient solar-driven interfacial water evaporation. At the molecular scale, we synthesize a photothermal functionalized COF-366-OH using photosensitive 5,10,15,20-tetrakis(4-aminophenyl) porphyrin (TAPP) and 2,5-dihydroxyterephthalaldehyde (DHTA) as building blocks. At the micro-nano scale, we introduce the π-conjugated catechol molecule 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) to regulate COF polycondensation and assembly, which enable the shaping of COF-366-OH into urchin-like nano-morphologies (namely UCOF-366-OH). The synthesized UCOF-366-OH exhibits high crystallinity, large surface area, excellent photothermal conversion capacity, and strong hydrophilicity. Furthermore, UCOF-366-OH is processed into a photothermal composite membrane. With localized solar heating and optimized water transport at the water evaporation interface, a high evaporation rate of 2.51 kg m−2h−1 with solar-to-vapor efficiency of 97.3 % is achieved. This work paves a new way for the multi-scale structural design of COF-based photothermal materials and highlights their innovative application in solar water evaporation.

Fabrication of Catechol Sensitized Hollow Microspheres ZnTiO3/TiO2/ZnO for the Photodegradation of Methylene Blue

AbstractDesigning new materials that can be used to treat environmental pollutants is one of the prime focuses of chemical science. Here, an unprecedented photocatalytic material with high activity of catechol sensitized ZnTiO3/TiO2/ZnO hollow microspheres was synthesized by hydrothermal method. The structure and properties of the composite photocatalyst were analyzed by various testing methods. The photocatalytic activity was evaluated by using methylene blue (MB) as the target degradation substance. The results demonstrated that catechol (CA) sensitized ZnTiO3/TiO2/ZnO photocatalyst is a hollow microsphere with a diameter of 1–1.5 mm, the CA molecules are covalently bonded to the ZnTiO3/TiO2/ZnO surface, and the composite photocatalyst has good light absorption and carrier separation performance. Under the condition of irradiation for 90 min, the degradation rate of the composite photocatalyst for MB was higher than that of ZnTiO3/TiO2/ZnO. When the loading amount of CA was 0.6 wt%, the degradation rate of CA/ZnTiO3/TiO2/ZnO for MB was as high as 98.28 %, and the reaction rate constant was up to 4.35×10−2 min−1. A reasonable mechanism of photocatalytic degradation of pollutants by catechol as sensitizer on ZnTiO3/TiO2/ZnO was proposed. This study provides a theoretical reference for efficient photodegradation of pollutants in the environment.

The Molecular Structural Analysis of Biologically Important Catechol Molecule: An Integrative Perspective from Experiments and Futuristic Tools

Background: Catechol is a phenolic molecule found naturally in plants. It is also known as pyrogallic acid or 1, 2-dihydroxybenzene. Catechol is currently produced commercially by decarboxylating gallic acid at high temperatures and pressures. Aims and Objectives: This research aimed to understand the biological importance of catechol and perform molecular structural analysis on catechol molecules. Methods: Catechol (1, 2, dihydroxy benzene) was studied via computational analysis by employing the use of DFT and B3LYP methods. Hirshfeld analysis was carried out to investigate crystal intermolecular interactions, and the NBO study was performed to study chemical donating and accepting interactions. Moreover, the computational study was performed using FTIR, HNMR and other instrumentation like AIM theory for circular dichroism data. Results: Furthermore, the surface iso-projection study and binding energy results did prove to run in alignment with experimentally obtained values from the computational studies. Fukui functional study and molecular electrostatic potential were utilized in the study to investigate interactions between anionic and cationic sites of catechol. In addition, molecular dynamic simulations revealed that biomolecular stability was also present. Thus, the antibiotic efficacy of catechol displayed chemical oxidative interactions that exhibited close chemical correlations with ascorbic acid, ellagic acid, and gallic acid. Conclusion: The catechol has been examined experimentally and theoretically. The results were compared with catechol spectra, including IR and UV-visible spectra generated through computer analysis. The experimentally observed spectra were found to be in parallel with theoretical data. According to drug-likeness investigations, the following compounds, gallic acid, ellagic acid, and ascorbic acid, were found to be closely related to catechol as an antibiotic. Hence, it can be concluded that catechol, whether in its entirety or in a portion, is a potent antibacterial, anti-inflammatory, and anti-malarial drug.

Catechol Sensing Performance of Pd-Functionalized Two-Dimensional Polyaramid: A DFT Investigation.

Catechol (Cc) molecule adsorption on a pristine and transition metal (TMs = Sc, Pd, and Cu)-functionalized two-dimensional polyaramid (2DPA) monolayer is systematically studied by the first-principles density functional theory method. The weak physisorption (-0.29 eV) and charge transfer of the Cc molecule with p-2DPA result in a very quick recovery time (150 μs), hindering the Cc sensing capability of p-2DPA. Although TM functionalization greatly improved the adsorption ability, the Pd-functionalized 2DPA was shown to be the best choice for Cc adsorption due to the reasonable adsorption energy of -1.39 eV and expedited charge transfer between the Cc and Pd atom. The change of band gap and, hence, the conductivity of the Pd-2DPA system in response to the adsorption of the Cc molecule demonstrate its higher sensitivity than that of p-2DPA. The work function sensitivity of Pd-2DPA upon the Cc adsorption is also investigated. In addition to the change in the electronic properties, the change in the optical properties of Pd-2DPA after Cc adsorption is also analyzed. The structural stability of Pd-2DPA is validated by performing ab initio molecular dynamics simulations at 300 K. The complete desorption of the Cc molecule from Pd-2DPA is attained by annealing the material at 550 K under visible light (τ = 5.4 s) and at 450 K under UV light (τ = 3.7 s). Moreover, the higher diffusion energy barrier of +1.35 eV confirmed that the functionalized Pd atoms did not diffuse through the crystal to form clusters. This study could lay a theoretical foundation for developing possibly new-generation sensors for detecting Cc molecules.

Rationalization of the light-induced electron injection mechanism in a model 1D ZnO nanowire-dye complex: insights from real-time TD-DFTB simulations.

Zinc oxide nanowires (ZnO NWs) possess a unique one-dimensional (1D) morphology that offers a direct pathway for charge transport. In this article, we present the first application of the real-time time-dependent density functional tight-binding (real-time TD-DFTB) method for a model hybrid system consisting of a catechol molecule adsorbed on a ZnO nanowire. The rationalization of the photoinduced electron injection to the 1D nanostructure is attained through quantum dynamics simulations, stressing the role of charge transfer in the new optical transitions upon dye adsorption. We provide a momentum-resolved picture of the photoexcitation dynamics, highlighting the charge accumulation in certain k-points, which could improve our understanding of these ultrafast processes. Finally, in the context of dye-sensitized solar cells (DSSCs) based on ZnO NW arrays, we provide a method to calculate the photoresponse obtaining similar results to experiments. This work paves the way towards the fast and accurate theoretical design of 1D optoelectronic nanodevices.

Lignin Functionalized with Catechol for Large‐Scale Organic Electrodes in Bio‐Based Batteries

Lignin, obtained as a waste product in huge quantities from the large‐scale cellulose processing industries, holds a great potential to be used as sustainable electrode material for large‐scale electroactive energy storage systems. The fixed number of redox‐active phenolic groups present within the lignin structure limits the electrochemical performance and the total energy storage capacity of the lignin‐based electrodes. Herein, the way to enhance the charge storage capacity of lignin by incorporating additional small catechol molecules into the lignin structure is demonstrated. The catechol derivatives are covalently attached to the lignin via aromatic electrophilic substitution reaction. The increased phenolic groups in all functionalized lignin derivatives notably increase the values of capacitance compared to pristine lignin. Further, solvent fractionation of lignin followed by functionalization using catechol boosts three times the charge capacity of lignin electrode.

A theoretical exploration of catechol sensitization of C-doped bronze TiO2 surfaces for photochemical systems

Doping with atom impurities is currently an attractive mechanism to enhance the optical absorption capacity of TiO2 and other inorganic oxide semiconductors. In this work, the electronic and optical properties of carbon-doped TiO2(B) (100) ultrathin surfaces were investigated using density functional theory (DFT) calculations, with the aim of evaluating their potential as photoelectrode for dye-sensitized solar cells (DSSCs). Carbon impurities were introduced onto oxygen sites located in the proximity of the surface and catechol was employed as a sensitizer model, focusing our study mainly on the evolution of the semiconductor’s electronic structure. The reduction of the band gap energy resulting from impurity states within the valence band of C-doped TiO2(B) was confirmed. Moreover, our findings suggest that C doping not only induces a stronger interaction between the catechol molecule and the surface but also, could increase the light absorption capacity of the material. Thus, carbon-doped TiO2(B) could act as a promising semiconductor for DSSCs and other photochemical systems.

Recent Developments in Catecholic Polymers: Polymerization and Applications

Abstract: Over the last few years, research on catechol-containing polymers has focused mainly on making mussel-inspired catechol-containing polymers and examining their adhesion ability onto various substrata under dry and wet conditions. Indeed, a surge of dopamine-bearing vinylic monomers such as dopamine acrylates and their protected ones have been homopolymerized or copolymerized with fittingly chosen comonomers for targeted applications. Novel polymerization methods such as RAFT and ATRP have been gratifyingly employed to realize these polymers with controlled molecular weights and polydispersity indexes. The protection of hydroxyl groups of the dopamine-based vinyl derivatives has been achieved with different groups, namely, alkyl, benzyl, acetal, silyl, and ester. Nevertheless, in several cases, the unprotected dopamine-based vinylic monomers have been unprecedentedly shown to undergo polymerization with no inhibition or retardation. Ring-opening polymerization has been applied to copolymerizing several oxiranecontaining dopamine monomers and catechol-containing monomers with cyclic comonomers with no major difficulty. Polymers from this method exhibited excellent scaffolds for preparing various materials with desired functions such as electronic conductivity and adhesion to a wide range of objects. Catechol and catechol-containing molecules have been subjected to polycondensation with a number of comonomers, such as formaldehyde, polyamines, polyols, and polyacids, polyisocyanates, under special conditions. These polycondensation resins have been evaluated mainly for their adsorption capacity towards heavy metals and dyes for wastewater decontamination. Proteins antifouling properties of some of these resins have been demonstrated as well. Their special chemistry allowed their use in realizing metal nanoparticles for different purposes.

Infiltration of La2NiO4+ᵟ-Type Electrodes with Nano-Oxide Catalyst to Modify Electrochemical Properties and Stability Using Biomolecular Surface Engineering

Solid oxide electrolysis cells (SOECs) have increased in importance in recent years due to their potential to cleanly and efficiently separate hydrogen and oxygen, or to instigate other chemical conversion reactions. SOECs require a combination of both high start performance and low long-term degradation for optimal electrodes. Additionally, Cr-poisoning from metal interconnect components threatens long-term degradation due to the ambient humidity of the electrolysis process. The most promising candidate for the oxygen electrode was (La,Sr)(Co,Fe)O3±δ (LSCF) due to its excellent electrical and catalytic properties, but it is challenged by a SrZrO3 phase, Cr-poisoning, and decreased oxygen ionic conductivity under high current loads due to its reliance on oxygen site vacancy (VÖ ) concentration. This drives interest into the Ruddlesden-Popper (R-P) phase, which has the general K2NiF4-type structure. Of these, La2NiO4+δ (LNO) is interesting, as its ionic conductivity mechanism is interstitial oxygen (Oï ) and it has no apparent reaction under Cr-poisoning. A challenge, however, is LNOs relatively low surface oxygen transport. As such, this project’s focus is on the surface engineering of a heterostructured oxygen electrode with LNO as a backbone and an infiltrated LaCoO3-δ (LCO)-based perovskite layer.In this work, the surface engineering of the LNO surface was completed by utilizing a novel wet biomolecular infiltration technique to ensure homogenous nano-particle coatings. The process involves a primary deposition of a catechol surfactant throughout the LNO electrode, and then a secondary deposition of the nano-catalyst solution. The catechol molecule that is deposited in the first step enables the adhesion of the nano-oxide, helping to chelate the complex oxide and assisting in the formation of the compound. No further deposition steps are needed, increasing the overall efficiency and the controllability of the microstructure, and allowing for the formation of the multicomponent nanomaterial at temperatures <800 °C. This has the additional benefit of minimalizing the densification and/or reaction of the nanomaterial with the electrode backbone (if not desired).The initial objective of the work was to characterize the nano-catalyst deposition process on the electrode surface, and define characteristics such as surface roughness, homogeneity, and particle size as function of deposition parameters and surfactant type/concentration. This work was completed initially on an electrode surrogate, YSZ single-crystal substrates. First, a deposition study was run on single-crystal, polished YSZ substrates, chosen for their flatness which simplifies the microstructural characterization through atomic force microscopy (AFM). AFM images from this deposition were processed to gather data on sample surface roughness, and both particle homogeneity and volumetric data, indicating which variables were most important to adjust. An example of these images can be seen in Figure 1 below, an AFM graph of the topography of deposited nano-particles. After defining the deposition process on flat YSZ substrates, the deposition methods were transferred to LNO symmetrical cells and full SOECs. Half and full cells were screen-printed on a YSZ electrolyte, with a GDC barrier layer, a 50-50 wt % LNO/GDC active layer, and an LNO current collector layer. The electrochemical impedance spectroscopy (EIS) tests were completed on infiltrated and non-infiltrated cells at different loading levels (defined by the impregnation variables) to evaluate the effectiveness of the nano-oxide surface engineering on the desired characteristics of surface oxygen transport and charge transfer reactions. The cells were tested in air and various steam concentrations up to 800 °C. Acknowledgments: This research was funded by the US Department of Energy, Project DE-FE0032116. We would also like to thank the WVU Shared Research Facilities for their support, specifically Dr. Qiang Wang, Dr. Marcela Redigolo, and Mr. Harley Hart for their help. Figure 1

An ab initio study of catechol sensing in pristine and transition metal decorated γ-graphyne

Catechol is a toxic biomolecule due to its low degradability to the ecosystem and unpredictable impact on human health. In this work, we have investigated the catechol sensing properties of pristine and transition metal (Ag, Au, Pd, and Ti) decorated γ-graphyne (GY) systems by employing the density functional theory and first-principles molecular dynamics approach. Simulation results revealed that Pd and Ti atom is more suitable than Ag and Au atom for the decoration of the GY structure with a large charge transfer of 0.29e and 1.54e from valence d-orbitals of the Pd/Ti atom to the carbon-2p orbitals of GY. The GY + Ti system offers excellent electrochemical sensing towards catechol with charge donation of 0.14e from catechol O-p orbitals to Ti-d orbitals, while the catechol molecule is physisorbed to pristine GY with only 0.04e of charge transfer. There exists an energy barrier of 5.19 eV for the diffusion of the Ti atom, which prevents the system from metal–metal clustering. To verify the thermal stability of the sensing material, we have conducted the molecular dynamics simulations at 300 K. We have reported feasible recovery times of 2.05 × 10−5 s and 4.7 × 102 s for sensing substrate GY + Pd and GY + Ti, respectively, at 500 K of UV light.

Terahertz spectra of curcumin and catechol co-crystals

Curcumin (CUR) is a commonly used pharmaceutical with anti-inflammatory, antioxidant and anti-cancer effects, but its solubility in water is relatively low. In recent years, pharmaceutical co-crystal has been an effective method of enhancing the solubility of limited water-soluble pharmaceuticals. Based on this, terahertz time-domain spectroscopy (THz-TDS) is used to study the THz spectra of curcumin-catechol co-crystal. Firstly, the experimental spectra of curcumin, catechol (CTL), their physical mixture and their co-crystal are measured in a range of 0.5–3.5 THz, respectively. The experimental data show that CUR obtains six THz absorption peaks, while CTL possess three THz absorption peaks, the physical mixture obtains four absorption peaks, and their CUR-CTL co-crystal obtains three absorption peaks. These results indicate that THz-TDS can effectively identify curcumin, catechol and their co-crystals. The fact that the absorption peak at 3.31 THz obtained in co-crystal is entirely different from those of raw materials, implying that new weak interactional forces are generated between CUR molecule and CTL molecule, the co-crystal forms a new three-dimensional structure compared with their raw materials. These results are also verified by X-ray diffraction spectra of raw material and their Co-crystal. Moreover, four possible theoretical forms of curcumin-catechol co-crystal are optimized and simulated by using density functional theory (DFT). The calculated results indicate that the data of co-crystal form III are in good agreement with the experimental spectrum, and the simulation effectively reconstructs the experimental spectrum. So it can be inferred that the co-crystal is formed through the hydrogen bond between the carbonyl C10=O3 of CUR and the hydroxy O61-H55 of CTL. In addition, depending on the good match between experimental data and theoretical results, it is found that the three absorption peaks in the co-crystal do not origin from the action of a single molecule, but the joint action of the functional groups of the two molecules under the driving by the hydrogen bond. The existence of weak interaction forces, such as the hydrogen bond, not only changes the structural parameters of the two molecules, but also reestablishes a new intermolecular force, which then affects the interactional motions of the co-crystal. This fact directly leads the CUR-CTL co-crystal to exhibit THz absorption peaks different from those of raw materials in the THz band.

Catalytic conversion mechanism of guaiacol as the intermediate of lignin catalytic pyrolysis on MgO surface: Density functional theory calculation

MgO has better catalytic effect on the alkylation reactions of methoxy phenols in the pyrolysis of lignin to form alkylated phenols, thus, the research on the conversion mechanism of methoxy phenols into alkylated phenols on the MgO surface is necessary. In this study, the catalytic conversion mechanism of guaiacol as a model compound of methoxy phenols on the MgO surface is investigated by density functional theory calculations. The possible reactions for the conversion of guaiacol on the clean MgO(100) and the H atom pre-adsorbed MgO(100) surfaces are discussed. The adsorption energies, adsorption structures, electronic structures, and energy barriers of guaiacol on the MgO(100) surfaces are obtained to illustrate the impact of pre-adsorbed H atom on the adsorption of guaiacol and the conversion mechanism of guaiacol. The results indicated that a hydrogen bond is generated between the O1 atom of guaiacol molecule and the pre-adsorbed H atom, resulting in the adsorption energy of guaiacol molecule on the MgO(100) surface is lower than that on the H atom pre-adsorbed MgO(100) surface. The energy barriers for the conversion of guaiacol molecule to form o-cresol molecule on the clean MgO(100) surface is higher than generate catechol molecule on the H atom pre-adsorbed MgO(100) surface. Thus, the results indicate that the presence of hydrogen source has a promotion effect on the conversion of methoxy phenols over MgO catalyst into alkylated phenols.

Density Functional Evaluation of Catechol Adsorption on Pristine and Reduced TiO2(B)(100) Ultrathin Sheets for Dye-Sensitized Solar Cell Applications

The introduction of defects is one of the most recurrent pathways to generate modifications to materials' electronic structure and surface reactivity. In this work, calculations based on the density functional theory (DFT) were applied to study the electronic properties of pristine and reduced TiO2(B)(100) ultrathin sheets to evaluate their potential as a semiconductor material for dye-sensitized solar cells (DSSCs). It was carried out by introducing vacancy defects on these surfaces and then adsorbing a catechol molecule, used as a model of a direct electron injection sensitizer (type-II dye), in different interaction configurations. Geometric, energetic, and electronic analyses were performed, focusing on the electronic structure changes and charge transfer between the dye and surface during molecular adsorption. The obtained results seem to indicate that a thickness of four layers is adequate to obtain a satisfactory slab model approximation of the TiO2(B)(100) surface. The presence of oxygen vacancy states among the majority of the reduced surfaces was observed as well as a reduction of the band gap energy value. Additionally, the adsorption of catechol in the reduced surface induced an increase in light absorption compared to the pristine model. These attributes suggest that reduced ultrathin sheets of TiO2(B) could be a suitable candidate as a photoelectrode for DSSC applications.

Remarkable enhancement in catechol sensing by the decoration of selective transition metals in biphenylene sheet: A systematic first-principles study

Motivated by the recent successful synthesis of biphenylene structure (Fan et al 2021 Science 372 852), we have explored the sensing properties of this material towards the catechol biomolecule by performing the first-principles density functional theory and molecular dynamics simulations. Pristine biphenylene sheet adsorbs catechol molecule with a binding energy of −0.35 eV, which can be systematically improved by decorating the transition metals (Ag, Au, Pd, and Ti) at various possible sites of biphenylene. It is observed that the catechol molecule is adsorbed on Pd and Ti-decorated biphenylene sheets with strong adsorption energies of −1.00 eV and −2.54 eV, respectively. The interaction of the catechol molecule with biphenylene and metal-decorated biphenylene is due to the charge transfer from the O-2p orbitals of the catechol molecule to the C-2p orbitals of biphenylene and d-orbitals of metals in metal-decorated biphenylene, respectively. From the Bader charge calculation, we found that 0.05e amount of charge is transferred from the catechol molecule to pristine biphenylene, which gets almost double (∼0.1e) for the Ti-decorated biphenylene sheet. The diffusion energy barrier for the clustering of the Pd and Ti atoms comes out to be 2.39 eV and 4.29 eV, computed by performing the climbing-image nudged elastic band calculations. We found that the catechol molecule gets desorbed from the pristine biphenylene sheet at 100 K but remains attached to metal (Pd, Ti) decorated biphenylene sheets at room temperature by performing the ab-initio molecular dynamics simulations. The Ti-decorated biphenylene sheet has more sensitivity toward catechol adsorption while the Pd-decorated biphenylene sheet has a suitable recovery time at 500 K. The results suggest that the Pd and Ti-decorated biphenylene sheets are promising materials for catechol detection.

Thermoplastic Starch and Graphite Biocomposite Electrode for Electrochemical Catechol Sensor

There is interest in obtaining alternative materials for application in electrochemical sensing. Thermoplastic starch (TPS) was used because it is a polymer with high availability and biodegradability, which can be incorporated into graphite (Gr) forming a conductive material. This work describes the characterization of the material produced by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), contact angle, X-ray diffraction (XRD) and Raman spectroscopy. The techniques used allowed to show a good interaction between graphite and TPS and confirmed the predicted conductive properties, showing the potential of application as a substrate, in the development of electrochemical sensors. Electrochemical characterization by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) was also carried out, which allowed defining the best proportion of graphite:TPS as the composite of 60:40 w/w. The technique of differential pulse voltammetry (DPV) was used to determine the catechol molecule over a range of 0.1 to 2.0 mmol l−1, showing a linear regression (R2) of 0.9996 and limit of detection (LOD) and limit of quantitation (LOQ) values equal to 1.85 × 10−6 mol l−1 and 6.18 × 10−7 mol l−1, respectively. The results showed good precision, selectivity, and stability, proving the application as an electrochemical sensor to detect catechol (CC) in contaminated water.

Hydrogen Titanate H2TiO3 Nanowires Derived from K2TiO3 as Potential Materials for Solar Cell Applications: A Theoretical Study

AbstractOne‐dimensional systems of titanium dioxide and titanates are interesting for the fundamental study of physical and chemical properties at the nanoscale. In this work we present the electronic structure, mechanical and optical properties of angstrom scale titanate derived nanowires (ASW) by means of density functional theory (DFT) and Density Functional based Tight Binding (DFTB). This one‐dimensional H2TiO3 nanostructure is an interesting real material that could serve for understanding, at a fundamental level, the physical properties of TiO5 concatenated polyhedrons derived from hydrogen titanates. The proposed structural model demonstrates to be locally stable according to phonon analysis, and it can be inferred that the one‐dimension structure is essentially preserved. The mechanical properties put this nanowire as a flexible material, that could be used in flexible substrates maintaining its electronic properties. Also, the capacity of this system to be sensitized with a catechol dye was explored. For this porpoise, the adsorption of the catechol molecule was tested showing that the most stable interaction corresponds to a dissociative chelate configuration. Finally, it was possible to verify the capability of the sensitized system for injecting electrons from the catechol dye to the nanowire under visible light exposure. Thus, we present these extreme one‐dimensional nanostructured materials as candidates for solar cell applications.

Torsional motions of the free and H-bonded hydroxyl groups of the catechol molecule

Torsional vibrations of free and hydrogen-bonded hydroxyl groups of the 1,2-dihydroxybenzene molecule are analyzed within the harmonic and anharmonic approximations, as well as by constructing a 2D potential energy surface formed by varying the torsional coordinates of the two OH groups. Calculation of the vibrational spectrum of the molecule in the harmonic and anharmonic approximations was performed at the MP2/acc-pVTZ level of theory. Calculations of the 2D potential energy surface were performed at the MP2/acc-pVTZ, MP2/CBS(T,Q), and CCSD(T)/acc-pVDZ levels of theory. Calculations of the 2D surfaces of dipole moment components and kinetic coefficients were performed at the MP2/cc-pVTZ and MP2/acc-pVTZ levels of theory. In the latter case, the formalism of Wilson’s s→ vectors was used. The energies of the first 100 stationary torsional levels are calculated and classified by irreducible representations of the molecular symmetry group C2V(M). Furthermore, the analysis of wave functions allowed us to assign most of the torsional states to the fundamentals, combinations, and overtones of the torsional vibrations of the hydroxyl groups of two conformers that have the point symmetry groups CS (I) and C2V (II). The tunneling frequencies between equivalent configurations of conformer I in the ground and excited torsional states are estimated. The calculated values of the frequencies of fundamental torsional vibrations of two OH groups and the tunneling splitting value of the first excited torsional state of the free hydroxyl group of conformer I are compared with the experimental data presented in a recently published work [J. Bruckhuisen et al., Molecules 26 (2021) 3645]. Torsional IR spectra of the molecule are modeled at different temperatures.

Activating a Semiconductor-Liquid Junction via Laser-Derived Dual Interfacial Layers for Boosted Photoelectrochemical Water Splitting.

The semiconductor-liquid junction (SCLJ), the dominant place in photoelectrochemical (PEC) catalysis, determines the interfacial activity and stability of photoelectrodes, whcih directly affects the viability of PEC hydrogen generation. Though efforts dedicated in past decades, a challenge remains regarding creating a synchronously active and stable SCLJ, owing to the technical hurdles of simultaneously overlaying the two advantages. The present work demonstrates that creating an SCLJ with a unique configuration of the dual interfacial layers can yield BiVO4 photoanodes with synchronously boosted photoelectrochemical activity and operational stability, with values located at the top in the records of such photoelectrodes. The bespoke dual interfacial layers, accessed via grafting laser-generated carbon dots with phenolic hydroxyl groups (LGCDs-PHGs), are experimentally verified effective, not only in generating the uniform layer of LGCDs with covalent anchoring for inhibited photocorrosion, but also in activating, respectively, the charge separation and transfer in each layer for boosted charge-carrier kinetics, resulting in FeNiOOH-LGCDs-PHGs-MBVO photoanodes with a dual configuration with the photocurrent density of 6.08 mA cm-2 @ 1.23 VRHE , and operational stability up to 120 h @ 1.23 VRHE . Further work exploring LGCDs-PHGs from catecholic molecules warrants the proposed strategy as being a universal alternative for addressing the interfacial charge-carrier kinetics and operational stability of semiconductor photoelectrodes.

Bis(catecholato-κ2 O,O')bis-(dimethyl sulfoxide-κO)titanium(IV).

Bis(benzene-1,2-diolato-κ2 O,O')bis-(dimethyl sulfoxide-κO)titanium(IV), [Ti(C6H4O2)2(C2H6OS)2], crystallizes with two crystallographically independent mol-ecules in the space group P21/c emulating ortho-rhom-bic Pbca symmetry (β = 90.0445 (9)°]. The two mol-ecules are related by pseudo-glide symmetry, broken by modulation of each one catecholate and dimethyl sulfoxide (DMSO) ligand. Twinning by pseudomerohedry was observed [twin ratio 0.5499 (7):0.4401 (7)]. Complex 3 was obtained by heating of diprotonated titanium tris-catecholate precursor 2H in DMSO, by formal displacement of a catechol mol-ecule by two DMSO mol-ecules. Complex 3 is just the second heteroleptic, mono-nuclear, neutral bis-catecholate complex with TiO6 metal coordination, the only other one being its bis-DMF analogue 6. The two mol-ecules of 3 exhibit a distorted octa-hedral geometry. The geometry and distortions from ideal symmetry of 3 are discussed and compared to 6 and to cationic tris-catecholate titanium complexes.

Hydrogen-bond-stabilized high density catechol monolayer on magnetite Fe3O4(111)

Catecholic anchor groups are widely used to immobilize functional molecules on various substrates. In this work, the structure and stability of catechol adsorbed on single-crystalline magnetite Fe3O4(111) surfaces have been studied experimentally with temperature programmed desorption, X-ray photoelectron spectroscopy and infrared reflection absorption spectroscopy in combination with periodic density functional theory calculations. The experimental results show that the adsorbed catechol monolayer is thermally stable up to 600 K. At higher temperature, complete combustion with involvement of lattice oxygen occurs. A high-coverage adsorption phase, which contains two catechol molecules per Fe3O4(111) unit cell (2cc/u.c.), is identified at low temperature, which transforms into a regular adsorption phase with one catechol molecule per unit cell (1cc/u.c.) at and above room temperature. Calculations show that the monodentate catechol-iron complex is favored over the bidentate catechol-iron complex for the 1cc/u.c. phase. Remarkably, intermolecular hydrogen bonds, as well as molecule-surface H-bond interaction trigger known cooperativity effects to stabilize the high-coverage, 2cc/u.c. phase.