H2O Solvent Research Articles

Polyethylene glycol assisted solvothermal synthesis of ZnIn2S4 with zinc vacancy and enhanced internal electric field for photocatalytic CO2 reduction

In this work, polyethylene glycol is adopted as the solvent for the synthesis of ZnIn2S4 photocatalyst by the solvothermal method. Compared with the pristine ZnIn2S4 synthesized in H2O solvent, those ones prepared in the polyethylene glycol solvent possess several unique features that are beneficial for photocatalytic CO2 reduction, such as the increased Zinc vacancy level, the enlarged band gap, and the enhanced built-in internal electric field. These features allow for better charge separation efficiency, thereby improving the photocatalytic activity. The optimized ZnIn2S4 can achieve a CO yield rate of 20.14 µmol/g/h at the gas-solid interface, which is 8.36 times that of the pristine ZnIn2S4.

Ether-Water Co-Solvent Electrolytes Enhanced Vanadium Oxide Cathode Cyclic Behaviors for Zinc Batteries.

Vanadium-based compounds are fantastic cathodes for aqueous zinc metal batteries due to the high specific capacity and excellent rate capability. Nevertheless, the practical application has been hampered by the dissolution of vanadium in traditional aqueous electrolytes owing to the strong polarity of water molecules. Herein, we propose a hybrid electrolyte made of Zn(ClO4)2 salt in tetraethylene glycol dimethyl ether (G4) and H2O solvents to upgrade the cycle life of Zn//K0.486V2O5 battery. The G4 jointly solvates with Zn2+ ions and replaces a portion of the H2O molecules in the Zn2+ solvation sheath. It forms a strong bond with H2O, reducing its activity, and significantly inhibiting vanadium dissolution and water-induced parasitic reaction. Consequently, the optimized electrolyte with H2O and G4 volume ratio of 5 : 5 enhances the cycling stability of Zn//K0.486V2O5 battery, enabling it to reach up to 600 cycles. In addition, the battery demonstrates a satisfactory reversible capacity of 475.7 mAh g-1 and excellent rate performance attributed to the moderate ionic conductivity (28.8 mS cm-1) of the hybrid electrolyte. Last but not least, in the optimized electrolyte, the symmetric Zn//Zn cells deliver a long cycling performance of 400 h, while the asymmetric Zn//Cu cells shows a high average coulombic efficiency of 97.4 %.

A thiazole-based colorimetric and photoluminescent chemosensors for As3+ ions detection: Density functional theory, test strips, real samples, and bioimaging applications

A Schiff-base Ethyl (E)-2-(3-((2-carbamothioylhydrazono)methyl)-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (TZTS) dual functional colorimetric and photoluminescent chemosensor which includes thiazole and thiosemicarbazide has been synthesized to detect arsenic (As3+) ions selectively in DMSO: H2O (7:3, v/v) solvent system. The molecular structure of the probe was characterized via FT-IR, 1H, and 13C NMR & HRMS analysis. Interestingly, the probe exhibits a remarkable and specific colorimetric and photoluminescence response to As3+ ions when exposed to various metal cations. The absorption spectral changes of TZTS were observed upon the addition of As3+ ions, with a naked eye detectable color change from colorless to yellow color. Additionally, the chemosensor (TZTS) exhibited a new absorption band at 412 nm and emission enhancements in photoluminescence at 528 nm after adding As3+ ions. The limit of detection (LOD) for As3+ ions was calculated to be 16.5 and 7.19 × 10−9 M by the UV–visible and photoluminescent titration methods, respectively. The underlying mechanism and experimental observations have been comprehensively elucidated through techniques such as Job’s plot, Benesi-Hildebrand studies, and density functional theory (DFT) calculations. For practical application, the efficient determination of As3+ ions were accomplished using a spike and recovery approach applied to real water samples. In addition, the developed probe was successfully employed in test strip applications, allowing for the naked-eye detection of arsenic ions. Moreover, fluorescence imaging experiments of As3+ ions in the breast cancer cell line (MCF-7) demonstrated their practical applications in biological systems. Consequently, these findings highlight the significant potential of the TZTS sensor for detecting As3+ ions in environmental analysis systems.

Textile-Based Adsorption Sensor via Mixed Solvent Dyeing with Aggregation-Induced Emission Dyes.

This study demonstrates a novel methodology for developing a textile-based adsorption sensor via mixed solvent dyeing with aggregation-induced emission (AIE) dyes on recycled fabrics. AIE dyes were incorporated into the fabrics using a mixed solvent dyeing method with a co-solvent mixture of H2O and organic solvents. This method imparted unique fluorescence properties to fabrics, altering fluorescence intensity or wavelength based on whether the AIE dye molecules were in an isolated or aggregated state on the fabrics. The precise control of the H2O fraction to organic solvent during dyeing was crucial for influencing fluorescence intensity and sensing characteristics. These dyed fabrics exhibited reactive thermochromic and vaporchromic properties, with changes in fluorescence intensity corresponding to variations in temperature and exposure to volatile organic solvents (VOCs). Their superior characteristics, including a repetitive fluorescence switching property and resistance to photo-bleaching, enhance their practicality across various applications. Consequently, the smart fabrics dyed with AIE dye not only find applications in clothing and fashion design but demonstrate versatility in various fields, extending to sensing temperature, humidity, and hazardous chemicals.

Hydrophilic Ti-MWW for catalyzing epoxidation of allyl alcohol

Titanosilicates are widely applied in the alkene epoxidation reactions with high reaction rate and selectivity to desired products. Their catalytic performance depends on the structure topology, the micro-environment of Ti active sites, and the hydrophobicity/hydrophilicity of zeolite framework. Herein, we focus on a hydrophilic substrate of allyl alcohol (AAL) and investigated catalytic performance of four titanosilicates (TS-1, Ti-MOR, Ti-MWW, and Re-Ti-MWW) in the AAL epoxidation reaction with hydrogen peroxide as the oxidant. Among them, Re-Ti-MWW, synthesized via the post-modification of Ti-MWW with piperidine, exhibited the highest activity. Moreover, the preferred solvent changed from MeCN for Ti-MWW to H2O for Re-Ti-MWW. The relative diffusion rate of AAL over Re-Ti-MWW was up to 466 × 10-7 s-1, much larger than those of other zeolites. The higher diffusion rate of Re-Ti-MWW was probably derived from the higher framework hydrophilicity as revealed by the smaller water contact angle of Re-Ti-MWW compared to the other zeolites, which contributed to the high activity in AAL epoxidation. In the continuous slurry reactor, Re-Ti-MWW achieved a high catalytic lifetime of 163 h, with the selectivity of desirable glycidol product maintained at > 97% in the H2O solvent system, showing high potential as an industrial catalyst for the AAL epoxidation reaction.

Distinct roles: Co-solvent and additive synergy for expansive electrochemical range and low-temperature aqueous batteries

The present study addresses the challenges encountered by aqueous lithium-ion batteries (ALiBs), specifically the limited electrochemical stability window and inadequate low-temperature energy retention. We propose a binary solvent electrolyte system comprising N,N-Dimethylformamide (DMF) as a co-solvent and 3-sulfolene (3SF) as an additive (5 wt.% 3SF in 9 M LiTFSI H2O/DMF with a molar ratio of 1:1). The H2O solvent ensures non-flammability and high safety, while DMF reduces the freezing point and enhances low-temperature conductivity. Additionally, DMF actively solvates Li+ ions, thereby reducing interfacial H2O content. Moreover, through the incorporation of the 3SF additive along with LiTFSI, a stable bilayer interphase film is formed on the anode surface effectively expanding the electrochemical stability window to 4.37 V. By leveraging the distinct roles played by solvents and additive, exceptional performance at both room temperature and low-temperature is achieved for the LiMn2O4/Li4Ti5O12 cell. Specifically, at room temperature, the cell demonstrates an initial coulombic efficiency reaching 90 %. Moreover, even after undergoing 300 cycles at 1 C, the capacity remains as high as 156.3 mAh g−1 (with a remarkable capacity retention rate of 96 %). Notably, in extremely low-temperatures of -30 °C, the cell exhibits excellent cycling performance which can still maintain a capacity retention rate of 98.8 % after 50 cycles. The proposed electrolyte design strategy, which takes into account both the bulk electrolyte and interfacial chemistry, presents a practical and feasible approach for the development of safe, low-temperature, and high-energy density ALiBs.

Efficient detection of Sn2+ by 4-aminobenzenesulfonamide based Schiff base chemosensor

A novel Schiff base colorimetric and fluorometric chemosensor N-((E)-2-hydroxy-3-methoxybenzylidene)-4-(((Z)-2-hydroxy-3-methoxybenzylidene)amino)benzenesulfonamide (SOV), has been designed, synthesized and characterized by using spectroscopic techniques. The chemosensor SOV showed selective and sensitive colorimetric sensing ability for Sn2+ metal ion in THF: H2O (9:1, v/v) solvent mixture exhibited colorless to light yellow changes. When Sn2+ ion was added, it showed a considerable fluorescence enhancement, because photoinduced electron transfer (PET) has been blocked. More importantly that spectroscopic studies showed SOV to be a fast-responding, low detection limit (3.034 × 10−9M), which are much lower than the WHO-approved drinking water concentration and a good binding constant (2.81 × 103M−1). Furthermore, it was discovered that the EDTA in chemosensor SOV made it to function as a reversible fluorescence probe towards the Sn2+ ions. A metal coordination, PET, as well as an internal charge transfer (ICT) process might be interpreted as the detecting mechanism based on physicochemical and analytical techniques such as 1H NMR spectra, FT-IR, Elemental analysis, ESI-mass spectrometry, Job’s plot, and DFT studies. Fluorescence imaging experiments of Sn2+ in living MCF 7 cells demonstrated its value of practical applications in biological systems.

Structure and isomerization behavior relationships of new push-pull azo-pyrrole photoswitches.

A family of stilbenyl-azopyrroles compounds 2a-d and 3a-d was efficiently obtained via a Mizoroki-Heck C-C-type coupling reaction between 2-(4'-iodophenyl-azo)-N-methyl pyrrole (1a) and different vinyl precursors. The influence of the π-conjugated backbone and the effect of the pyrrole moiety were correlated with their optical properties. Studies via UV-Visible spectrophotometry revealed that the inclusion of EWG or EDG favors a red-shift of the main absorption band in these azo compounds compared with their non-substituted analogues. Furthermore, there is a clear influence between the half-life of the Z isomer formed by irradiation with white light and the push-pull behavior of the molecules. In several cases, the stilbenyl-azopyrroles led to the formation of J-type aggregates in binary MeOH : H2O solvents, which are of interest for water compatible applications.

A thiophene-linked terpyridine based phenanthridine chemoreceptor for Cd2+ and Cr3+ selective ratiometric fluorescence detection in environmental water and rice samples

BackgroundThe studied materials, Cadmium (Cd2+) and Chromium (Cr3+) are highly toxic, and it focuses on investigating various environmental sources, such as industrial processes and waste water. When quantities of Cr3+ and Cd2+ exceed the allowable limit, biological toxicity and hazardous environmental pollution are unavoidable. In order to address this problem, we introduce 5-(5-(4-([2,2':6′,2″-terpyridin]-4′-yl) phenyl) thiophen-2-yl)-7,8,13,14-tetrahydrodibenzo [a,i] phenanthridine (TPTP), a dual-emission response chemosensor that employs a colorimetric and fluorescence turn-on approach for the rapid, sensitive, and discriminate detection of Cr3+ and Cd2+ ions. ResultsWe created a newly designed luminous TPTP sensor based on intramolecular charge transfer (ICT). TPTP sensor probe specifically determined Cr3+ and Cd2+ ions with an immediate colour shift from cyan to green and orange in CH3CN: H2O (6:4) solvent solution. The permissible level set by the Environmental Protection Agency (EPA) of the United States for the presence of Cr3+ and Cd2+ ions in drinking water was higher than the detection level of 3.5 and 9.7 nM, by this sensor respectively. NMR titrations, HRMS, and theoretical calculation methods were employed to examine the accurate sensing processes of TPTP and complexes. SignificanceThis is an effective method of detecting Cr3+ and Cd2+ ions in an environmental system using a ratiometric methodology. In addition, TPTP was used to determine the concentration of Cr3+ and Cd2+ ions in natural water and food samples. Fluorescent bio-imaging studies revealed that the present sensor TPTP could identify Cr3+ and Cd2+ ions inside living HeLa cells. A paper kit analysis has been done on TPTP, which has a time-to-result of less than 1 s and offers a cost-effective assay. As a result, the platform offers portability.

Inhibition of corrosion of an aluminum alloy by rosemary and eucalyptus extracted oils in 1M hydrochloric acid medium: an experimental and theoretical study.

In this study, we explored aluminum corrosion inhibition field of study in a 1M HCl solution, harnessing the power of essential oils extracted from rosemary and eucalyptus plants. Our exploration gives a comprehensive analysis of the pivotal factors that shape the corrosion inhibition process. Our scientific journey was marked by a deliberate and systematic approach, encompassing the utilization of gravimetric analysis (weight loss), electrochemical potentiodynamic polarization, and the sophisticated electrochemical impedance spectrometry (EIS) techniques. Our findings unveiled promising and nuanced outcomes, particularly in the area of the electrochemical technique. This method demonstrated remarkable inhibition efficiencies, ranging from 42% to an impressive 92% for rosemary essential oil and from 37 to 84% for eucalyptus essential oil. These results unveiled a dynamic relationship between essential oil concentration and inhibition efficiency, a revelation that further deepens our understanding of the corrosion inhibition process. The inhibition efficiency increased with higher concentrations of essential oil but decreased with elevated temperatures. Furthermore, our analysis traversed into the realms of potentiodynamic and thermodynamic insights. These analytical techniques unearthed the complex mechanisms at play, explaining the pathway followed by the studied inhibitors. They exhibited their prowess by forming protective films on the metal surface, acting as vigilant protectors against the relentless forces of corrosion. Complementing our experimental findings, our study of computational chemistry through density functional theory (DFT) unveiled remarkable insights. It elucidated the spontaneous adsorption process of inhibitor molecules onto the aluminum surface in the presence of H2O solvent. This computational harmony with our experimental results strengthened our confidence in the robustness of our findings. One of the key findings of this study was the superior inhibitory power of camphor in rosemary EO and β-myrcene in eucalyptus essential oil EO, respectively, attributed to the distinctive characteristics of the active sites found in each compound. The inhibitory effectiveness followed the order β-myrcene > camphor > borneol > α-pinene > bornyl acetate > p-cymene > 1,8-cineole. These compounds, notable for their distinct active sites, emerged as exceptional agents in the pursuit of effective corrosion inhibition.

A green approach for genistein and apigenin extraction optimization from by-products of soybean crops

Soybeans’ genistein and its isomer apigenin are widely studied bioactive compounds owing to their therapeutic potential for treating various health disfunctions. A green extraction of both from soy by-products could lead to a valuable and sustainable approach to adding value to these materials in a biorefinery context. Here Hansen Solubility Parameters (HSP) and the Conductor-like Screening MOdel for Real Solvents (COSMO-RS) were applied to screen green molecular solvents and Natural Eutectic Solvents for the extraction of genistein and apigenin from soy by-products. The predicted solubilities of genistein and apigenin in 18 shortlisted candidates were experimentally tested by dynamic maceration, the most industrially implemented natural products extraction technique. EtOH:H2O (8:2, v/v) and natural eutectic solvent (NAES) betaine:ethylene glycol (1:2, mol/mol) showed the highest performance. These were selected for extraction optimizations by Design of Experiments from soy branches, the largest by-product by mass. The optimum condition of each solvent was applied to extract all other parts of soy collected post-mechanical harvesting. The highest value of apigenin, 591.49 ± 26.7 μg/g, was achieved from soy pods with EtOH:H2O (8:2, v/v), while the highest of genistein, 54.04 ± 3.39 μg/g, was achieved from soybeans using the same solvent. Our findings highlight the necessity of exercising caution when interpreting in silico outcomes in the context of metabolite extractions from complex matrices. A trade-off between in silico solvent screening and experimental work should be followed when developing new phytochemical extraction processes. Furthermore, soy by-products emerged as competitive candidates for a long-term source of the bioactive apigenin in a biorefinery context.

Obtaining the Enoxaparin Sodium Substance Equivalent to the Original Clexane® and Lovenox®. The Selection of Technological Parameters and Optimization of the “Greenness” of the Purification Stage

The aim of the study was to adjust and optimize the purification stage of crude enoxaparin sodium to obtain a substance equivalent to the original drugs Clexane® and Lovenox® according to the criteria specified by the FDA. The purification stage involves the reprecipitation of crude enoxaparin in methanol. Determining the ratio of solvents required for the reprecipitation is important for studying the correlation between the experimental conditions of the technological process and the structural characteristics of enoxaparin samples. In the study, the method of purification of enoxaparin sodium described in the patent was assessed, and the following variations of the MeOH:H2O solvent ratio were selected – 4:1; 2:1; 1:1. The obtained samples of enoxaparin sodium were analyzed according to the in-house specification developed on the basis of the pharmacopoeial monograph, as well as by non-pharmacopoeial methods, such as two-dimensional NMR spectroscopy (HSQC) and size exclusion chromatography (SEC) for detailed characterization of the molecule. Strategies of greening of the enoxaparin sodium purification stage by reducing the E-factor were also considered in the study. Considering the principles of “green” chemistry, the method of purification of crude enoxaparin sodium was optimized by the solvent regeneration. It was experimentally possible to demonstrate the effect of the solvent ratio at the stage of purification of crude enoxaparin on the composition, as well as on the number and distribution of oligosaccharide fractions in the molecule. Based on the results of the study, it can be concluded that the ratio of MeOH:H2O=1:1 allows obtaining samples that are closest to Clexane® and Lovenox® in terms of the molecular weight distribution profile and the composition profile. The E-factor was also reduced from 14 to 5.25 by solvent regeneration.

Integrated process towards sustainable renewable plastics: Production of 2,5-furandicarboxylic acid from fructose in a base-free environment

We report an integrated approach to produce 2,5-furandicarboxylic acid (FDCA) using fructose as a feedstock in a base-free environment, thus providing a promising alternative to the current protocol. FDCA, an alternative molecule to terephthalic acid (obtained from the petroleum route), is used to synthesize poly(ethylene-2,5-furanoate) (PEF), a renewable plastic. In our approach, we produced 5-hydroxymethylfurfural (HMF; 84% yield) by fructose dehydration in an acetone (Ace)/H2O solvent system. The obtained HMF feed was subsequently oxidized over Ru/MnO2, producing FDCA in 92% yield under base-free conditions. The Ru/MnO2 catalyst outperformed conventional Pt/C and Ru/C catalysts under identical reaction conditions. Our novel approach for FDCA production via an integrated process using an Ace/H2O solvent mixture under base-free conditions is economically feasible and environmentally friendly. To the best of our knowledge, this work is the first to report the production of FDCA via this route. We postulate that the high catalytic efficiency of the sulfonated porous organic polymer and Ru/MnO2 in an Ace/H2O system renders them superior to existing homogeneous catalytic routes for HMF production and conversion into FDCA via a scalable process.

Simultaneous determination of crocin and crocetin in food samples by highperformance liquid chromatography (HPLC-PDA)

Crocin and crocetin are two bioactive compounds found in saffron and gardenia. In the food industry, due to their natural yellow or orange color, they are used as food colouring. The study was carried out to optimize the high-performance liquid chromatography combined with a photodiode detector (HPLC-PDA) to simultaneously determine the crocin and crocetin content in food. Analytical samples were ultrasonicated with ACN:H2O (1:1, v/v) solvent for 30 minutes. The sample solution was determined by HPLC – PDA with the following conditions: Sunfire C18 column (250 mm x 4.6 mm; 5 µm) mobile phase consisting of 0.1% formic acid and ACN using gradient program. The method has good specificity, the standard curves of crocin and crocetin have correlation coefficients R2 > 0.999, respectively, repeatability and recovery meet AOAC requirements. The limit of detection (LOD) for  crocin and crocetin were 0.5 mg/kg and 0.25 mg/kg, respectively. The method has been applied to simultaneously determine crocin and crocetin in 15 real samples and results in 13 out of 15 samples detecting crocin content, 11 out of 15 samples detecting crocetin content, and in 2 out out of 15 samples. neither crocin nor crocetin was detected. The gardenia powder group contained the highest content of crocin and crocetin (23.5 g/100g – 24.4 g/100g) and dried lychee samples - sun-dried or dried gardenia contains the second highest concentrations of crocin and crocetin in the food group.

Electron confinement promoted the electric double layer effect of BiOI/β-Bi2O3 in photocatalytic water splitting

In the realm of photocatalysis, understanding the interface issues (solid/solid and solid/liquid) inherent in heterojunction at the atomic level is the ultimate for engineering an efficient photocatalyst. Herein, an electrophoretic deposition technique is adopted to synthesize BiOI/β-Bi2O3 heterojunction, exhibiting superior photocatalytic activity and stability in H2 evolution (91.5 μmol g–1 h−1) and H2O2 production (11.3 mg L–1 h−1). Combined with the experimental and computational results, a lower free energy of hydrogen evolution reaction (252.4 meV) has been observed contrast to BiOI and β-Bi2O3 samples. A carrier transfer process of like S-scheme heterojunction is proposed based on density of states (DOS) and carrier distribution calculations. The theoretical calculations illustrate the transition dipole moment, migration and accumulation of carrier in BiOI/β-Bi2O3 heterojunction. Subsequent ab initio molecular dynamics (AIMD) results of solid/liquid interface systems (BiOI/β-Bi2O3/H2O and β-Bi2O3/H2O) unravel the interface H2O (solvent) behaviors. The local aggregation of photo-generated electrons in BiOI/β-Bi2O3/H2O leads to a large potential drop, high proton migration rate and the steady electric double layer (EDL) structure compared to the β-Bi2O3/H2O, which facilitates the occurrence of photocatalytic reactions in solution. In addition to offering new insights into the hydrogen evolution and proton transfer in the EDL model and the association between the heterojunction effect and EDL structure, this work also introduces a novel design strategy for Bi-based heterojunctions.

A 3D supramolecular framework-based electrochemical sensor for highly sensitive detection of ascorbic acid

A benzimidazole carboxylate ligand with multiple coordination sites has been designed by the aldimine condensation reaction of 2-pyridinecarboxal-dehyde and 3,4-diaminobenzoic acid, 2-(2′-pyridyl)-benzimidazole-6-carboxylic acid (H2pybimc), which solvothermally assembled with Ni2+ ions in the mixed solvents of H2O and n-propanol to generate a 3D supramolecular framework, {[Ni(Hpybimc)(NO3)(H2O)]}n (CP 1). The chemical composition and structure of CP 1 have been characterized in detail by various tools. Structural analysis demonstrates that the asymmetrical unit of CP 1 consists of one octahedral Ni2+ ion, one Hpybimc−, one NO3− and one coordinated water molecule. Adjacent Ni2+ ions are linked by Hpybimc− to form a 2D 3-connected ‘fes’-type topology, which further generates a 3D supramolecular architecture by hydrogen bonds and π···π stacking interactions. The carbon paste electrode (CPE) modified with CP 1 is fabricated (CPE 1) and applied for the electrochemical sensor of ascorbic acid (AA), which exhibits good linear correlation with AA in the concentration range of 5.0 × 10−4 to 7.3 mmol L−1 with the limit of detection (LOD) of 0.85 μmol L−1. Moreover, it has satisfactory stability, repeatability, and selectivity towards AA, which can be successfully used for the detections in real samples.

Mussel-Inspired Wet-Adhesive Multifunctional Organohydrogel with Extreme Environmental Tolerance for Wearable Strain Sensor.

As a flexible artificial material, the conductive hydrogel has broad application prospects in flexible wearable electronics, soft robotics, and biomedical monitoring. However, traditional hydrogels still face many challenges, such as long-term stability, availability in extreme environments, and long-lasting adhesion to the skin surface under sweaty or humid conditions. To circumvent the above issues, one kind of ionic conductive hydrogel was prepared by a simple one-pot method that dissolved chitosan (CS), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), tannic acid (TA), and 2-methoxy-ethyl acrylate (MEA) into dimethyl sulfoxide (DMSO)/H2O solvent. The resulting hydrogel showed excellent tensile properties (1440%), extreme environmental tolerance (-40-60 °C), adhesion (72 KPa at porcine skin), ionic conductivity (0.87 S m-1), and high-efficiency antibacterial property. Furthermore, the produced organohydrogel strain sensor exhibited high strain sensitivity (GF = 4.07), excellent signal sensing capabilities (human joint movement, microexpression, and sound signals), and long-term cyclic stability (400 cycles). Looking beyond, this work provides a simple and promising strategy for using hydrogel sensors in extreme environments for e-skin, health monitoring, and wearable electronic devices.

Unveiling the adsorption and inhibition mechanism of thiadiazole derivatives for mild steel corrosion in hydrochloric acid based on experimental approaches and first-principles calculations

In this work, two eco-friendly thiadiazole derivatives, 5-amino-1,2,3-thiadiazole (AT) and N-phenyl-N-1,2,3-thiadiazol-5-yluree (thidiazuron, TDZ), were employed to alleviate the corrosion of mild steel in hydrochloric acid medium. Electrochemical tests show that compared to AT, TDZ exhibits a much better inhibitive effect with an inhibition efficiency of 98.95% at 0.6 mM. The introduced side chain with phenyl ring in TDZ molecule endues it with more adsorption sites, which facilitates the strong absorption of TDZ by the extra bonding of O atom and phenyl ring with steel surface. The DFT-based first-principles calculations indicate that AT and TDZ could adsorb on the steel surface through the thiadiazole ring, O atom and phenyl ring by forming Fe–S, Fe–N, Fe–O, and Fe–C bonds. The parallel adsorptions of AT and TDZ are more stable with more negative adsorption energy than their perpendicular adsorptions. Furthermore, the non-covalent interaction between AT/TDZ and H2O solvent molecules deteriorates their adsorptions on steel surface.

Accelerating the concerted double proton transfer process of 2,2′-bipyridine-3,3′-diol-5,5′-dicarboxylate acid ethyl ester (BPDC) molecule by centrosymmetric dual intermolecular hydrogen bonds

This study has conducted a systematic investigation into the excited state double proton transfer (ESDPT) process of 2,2′-bipyridine-3,3′-diol-5,5′-dicarboxylate acid ethyl ester (BPDC) in cyclohexane (CYH) and water (H2O) by density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The calculated geometrical parameters, reduced density gradient and infrared vibration spectra confirm that BPDC undergoes the ESDPT process in both CYH and H2O. In comparison to the CYH solvent, the intramolecular hydrogen bonds (IAHBs) are strengthened in the S0 state by the formation of centrosymmetric intermolecular hydrogen bonds (IEHBs) between H2O and the OH group of BPDC molecules. Furthermore, the constructed potential energy surfaces show that BPDC molecules undergo a concerted ESDPT process without potential barriers in both solvents. Time evolution analysis confirms that the ESDPT process of BPDC molecules in H2O solvent (19 fs) is faster than that in CYH solvent (62 fs). The results indicate that the formation of IEHBs causes zero disruption to the original I AHBs, but it can effectively promote the ESDPT process of BPDC molecules. Overall, this work serves as important theoretical guidance for the development of high-performance fluorescence materials.

Molecular aggregation kinetics of Heteropolyene: An Experimental, topological and solvation dynamics studies

Herein, we have demonstrated the solvent specific ground state and excited state aggregates of the molecule ((1E,2E)-1,2-bis((E)-3-phenylallylidene)hydrazine: BISCH) in solution. The nature of aggregation at ground state and excited state is different in H2O solvent. The rate of aggregation in water is calculated from steady state absorption and fluorescence spectroscopy respectively. Excited state fluorescence behaviour contributed from aggregates and non-aggregates species have been identified by time resolved fluorescence spectroscopy in H2O. Aggregation is highly sensitive towards solvent polarity and nature of solvent. The effect of solvent on aggregation process has been discussed and explained on the basis of relative change of hydrophobic and hydrophilic interaction of solute-solvents in solution. Further, J-type aggregation of BISCH is also observed in H2O. Further, using 1st order aggregation kinetic model for ground and excited state,) aggregation rate constant has been calculated and found to 8.0x10-4s−1 ((kagg@312 nm) and 1.2x10-4s−1 (kagg@413 nm) respectively. Effect on molecular geometry depending upon Interaction sites of BISCH and solvent molecule is also discussed with the results from DFT calculation. NBO, NCI, DOS, MESP along with various topological analysis are performed for BISCH in water. For BISCH…water molecular system, NBO interaction is observed due to delocalization of lone pair of O35 and N36 to antibonding of H37-O38 and H40-O41, respectively. ELF, LOL, AIM and ALIE calculation are employed to locate the site and magnitude of hydrogen bonding interactions. The AIMD study for BISCH in water shows minimum of the total energy between 125 and 175 fs and 225–275 fs. N…H-O hydrogen bonding interactions such as N36-H40 and N35-H37 varies from 1.8 to 2.6 Å during the molecular dynamics simulation.