UV Vis Spectroscopy Research Articles

Ultrafast photoinduced charge carrier dynamics of L-cysteine and oleylamine stabilized CsPbBr3 perovskite quantum dots coupled with gold nanoparticles.

We have synthesized L-cysteine and oleylamine stabilized CsPbBr3 perovskite quantum dots (PQDs) and coupled them with gold nanoparticles (AuNPs). The PQDs and AuNPs, as well as their hybrid nanostructures (HNS), were characterized using UV-visible (UV-vis) and photoluminescence (PL) spectroscopy. The UV-vis spectra show absorption bands of the HNS at 503 and 520nm, attributed mainly to PQDs and AuNPs, respectively. The PQDs show a strong excitonic PL band peaked at 513nm from PQDs. The HR-TEM results show the formation of hybrid structures between PQDs and AuNPs, which is also supported by the PL quenching of the PQDs by the coupled AuNPs. Ultrafast dynamics of the exciton and charge carriers in the HNS and pristine PQD were studied using femtosecond transient absorption. Multiexponential fitting of the dynamic data revealed the existence of shallow and deep trap states in pristine PQDs and ultrafast electron transfer from PQDs to AuNPs in the HNS. A kinetic model was proposed to account for the key dynamic processes involved and to extract the time for electron transfer from PQDs to AuNPs in the HNS, found to be ∼2ps. Dynamic processes in pristine PQDs are largely unchanged by HNS formation with AuNPs.

Myco-Biosynthesis of Silver Nanoparticles, Optimization, Characterization, and In Silico Anticancer Activities by Molecular Docking Approach against Hepatic and Breast Cancer

This study explored the green synthesis of silver nanoparticles (AgNPs) using the extracellular filtrate of Fusarium oxysporum as a reducing agent and evaluated their antitumor potential through in vitro and in silico approaches. The biosynthesis of AgNPs was monitored by visual observation of the color change and confirmed by UV–Vis spectroscopy, revealing a characteristic peak at 418 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses showed spherical nanoparticles ranging from 6.53 to 21.84 nm in size, with stable colloidal behavior and a negative zeta potential of −15.5 mV. Selected area electron diffraction (SAED) confirmed the crystalline nature of the AgNPs, whereas energy-dispersive X-ray (EDX) indicated the presence of elemental silver at 34.35%. A face-centered central composite design (FCCD) was employed to optimize the biosynthesis process, yielding a maximum AgNPs yield of 96.77 µg/mL under the optimized conditions. The antitumor efficacy of AgNPs against MCF-7 and HepG2 cancer cell lines was assessed, with IC50 values of 35.4 µg/mL and 7.6 µg/mL, respectively. Molecular docking revealed interactions between Ag metal and key amino acids of BCL-2 (B-cell lymphoma-2) and FGF19 (fibroblast growth factor 19), consistent with in vitro data. These findings highlight the potential of biologically derived AgNPs as promising therapeutic agents for cancer treatment and demonstrate the utility of these methods for understanding the reaction mechanisms and optimizing nanomaterial synthesis.

Synthesis of Trimanganese Tetraoxide (Mn3O4) as a promising electrode and Photocatalyst for the degradation of Rhodamine B dye

The article involves the facile bio-synthesis of Manganese (III) Oxide (Mn3O4) nanoparticles (NPs) using Curry leaf (Murraya Koenigii) extract as an efficacious chelating agent. The prepared NPs were subjected to various characterization methods such as Powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) Analysis, Transmission Electron Microscopy (TEM), Fourier Transform Infrared analysis (FTIR), Ultra Violet spectroscopy study (UV–Vis), Cyclic Voltammetry (CV) and Vibrating Sample Magnetometer (VSM) to study the crystalline structure, morphology, optical properties, electrochemical activity and magnetic property of the sample. The XRD result proved the crystallinity of the sample having crystallite size around 15 nm with tetragonal structure. The absorption band observed at 612 cm−1 indicates the Mn-O stretching modes of tetrahedral sites in FTIR analysis of the prepared sample which confirmed the formation of Mn3O4 NPs. Using SEM and TEM techniques, the surface morphology and NPs size were examined. The composition and distribution of the NPs was verified using EDX spectrum and elemental mapping. Using the UV–Visible spectroscopy, the energy band gap (Eg) for the NPs was computed and calculated as 2.34 eV. The Mn3O4 NPs evinced a specific capacitance of 276 Fg-1 at 10 mV/s scan rate. This result proposes that the obtained Mn3O4 NPs can be used as a suitable electrode mainly for supercapacitor applications. VSM study revealed the paramagnetic behavior of the synthesized Mn3O4 NPs. The synthesized Mn3O4 NPs exhibited moderate antibacterial activity with gram positive bacteria such as Staphylococcus aureus, Streptococcus pneumoniae, and gram negative bacteria such as Klebsiella pneumoniae, with the inhibition zones of 12, 10, and 9 mm respectively. Photo catalytic degradation study was carried out for Rhodamine B (RhB) dye, which showed a strong characteristic absorption peak nearly at 554 nm with 94 % of degradation efficiency.

Green synthesised Mn3O4 and poly (o-phenylenediamine) for antimicrobial textile-based supercapacitor applications

The advancement of wearable supercapacitors (SCs) has recently garnered a lot of attention owing to their ease of fabrication into textiles, low cost, long cycle life, fast charging and discharging, high efficiency, and ability to bridge the energy and power gap between conventional capacitors and batteries. The present study focuses on the development of wearable textile-based SC electrodes using green-synthesised manganese oxide nanoparticles functionalised on poly(o-phenylenediamine) reinforced to a polymer nanocomposite. The prepared nanocomposite was characterized using spectroscopic techniques such as UV-visible spectroscopy, Fourier transform infrared spectroscopy, x-ray diffraction studies, and scanning electron microscopy to validate the incorporation of metal oxide nanoparticles into the polymer matrix. The thermal properties were studied using thermogravimetric analysis and differential scanning calorimetry. The electrochemical performance of the bare polymer and the nanocomposite was evaluated using cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy techniques. An impressive specific capacitance of 213 Fg-1was achieved at a current density of 1 Ag-1for the polymer nanocomposite and even after 1000 cycles a capacitance retention of 89% was observed. Enhanced antimicrobial activity was also observed for the nanocomposite against both gram-negative and gram-positive bacteria. Based on these attributes, the fabricated device can be used as an efficient antimicrobial wearable SC.

Synthesis and release studies on amylose-based ester prodrugs of fenamic acid NSAIDs.

Aim: To achieve colon-targeted release of mefenamic acid from its ester-linked amylose prodrugs.Materials & methods: The prodrug was characterized by 1H NMR and IR spectroscopy. Drug activation and release profile was studied in enzyme enriched simulated physiological media via UV-vis spectroscopy and was validated with HPLC analysis. ELISA assay was employed for evaluating the % inhibition of COX-1 and COX-2 inhibition at different concentrations of the prodrug preincubated with ester and/ or amylose hydrolyzing enzymes. SEM studies further validated the performance of the prodrug under simulated physiological conditions.Results: Pancreatin was essential for the prodrug activation in SIM to make the ester bonds in prodrug vulnerable to hydrolysis by esterase. This evidence was confirmed by drug release studies, HPLC analysis, ELISA assay and SEM investigation where the ester conjugated prodrug showed marked stability in physiological media only to get activated in the presence of amylose degrading enzyme.Conclusion: Ester linked amylose-mefenamic acid conjugate showed both enzyme responsive activation and release in SIM.

Reaction Time Induced a Two-Step Dissolution and Recrystallization Structural Transformation with Three Eu Metal-Organic Frameworks: Crystal Structures and Multiresponsive Fluorescence Detection.

Under solvothermal conditions, three 3D lanthanide metal-organic frameworks (Ln-MOFs): [Eu(H2DHTA)1.5(DMF)2]·DMF (1), [Eu(H2DHTA)0.5(DHTA)0.5(DMF)(H2O)]·2H2O (2), and Eu(HCOO)3 (3) (H4DHTA = 2,5-dihydroxyterephthalic acid) have been synthesized by different reaction times. Interestingly, induced by reaction time, compounds 1-3 underwent a two-step dissolution and recrystallization structural transformation (DRST) reaction. Investigations on the DRST processes were carried out, and the transformation pathway was deduced, which was verified by XRD analyses. Notably, compound 2 demonstrates pronounced luminescence as well as high stability in water and other organic solvents. The fluorescent detection of furan antibiotics can serve as turn-off effects, and glutamic acid (Glu), aspartic acid (Asp), and riboflavin (VB2) can serve as the turn-on effect. To explain the enhancing and quenching mechanisms, XRD, UV-visible absorption spectroscopy, electrochemistry, IR spectra, theoretical calculation, fluorescence lifetimes, and XPS were discussed. Additionally, MOF-coated test strips were utilized to detect these analytes, exhibiting excellent agreement with fluorescence spectroscopy. This work provides an example for more effective designs to employ Ln-MOFs as multiresponsive fluorescent sensors for detection of environmental pollutants in aqueous solution.

Biosynthesis of Silver Nanoparticles Using Barleria albostellata C.B. Clarke Leaves and Stems: Antibacterial and Cytotoxic Activity

Silver nanoparticles (AgNPs) have increasingly gained attention owing to their distinctive physicochemical and biological properties. The objective of the investigation was to biologically synthesize AgNPs using plant extracts from Barleria albostellata. The synthesized AgNPs, obtained from B. albostellata (leaves and stems), were characterized through various techniques including UV-visible spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray analysis, Fourier transform infrared (FTIR) spectral analysis, and nanoparticle tracking analysis (NTA). The antibacterial efficacy of the synthesized AgNPs was evaluated utilizing the disk diffusion method. The cytotoxicity effects of the synthesized AgNPs were determined using the MTT assay (3-[(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide]) in cervical cancer (HeLa), embryonic kidney (HEK293), and breast adenocarcinoma (MCF-7) cell lines. The results indicate that B. albostellata extracts could serve as eco-friendly biofactories for the synthesis of AgNPs. UV-vis spectroscopy of the leaf and stem extracts revealed absorption peaks within the range of 400–450 nm, thereby confirming the synthesis of AgNPs. Elemental Ag was highest in the methanol leaf extracts (16.87 ± 0.89%) and lowest in the powdered stem extracts (7.13 ± 1.44%). Synthesized AgNPs were predominantly spherical in shape. HRTEM revealed that synthesized AgNPs from the methanolic stem extracts (34.32 ± 16.99 nm) were larger in size, while those from the powdered stem extracts were smaller (16.57 ± 5.55 nm). AgNPs synthesized from both the leaf and stem extracts exhibited zeta potential values between −8.8 and −32.1 mV, with hydrodynamics diameters ranging from 34.3 to 111.3 nm. FTIR spectroscopy confirmed the presence of various functional groups on the AgNPs. AgNPs synthesized from the leaf and stem extracts displayed significant antibacterial activity and were sensitive to Gram-negative and Gram-positive bacteria. AgNPs exhibited significant antibacterial activity (diameter of the zone of inhibition) against Pseudomonas aeruginosa (21.67 ± 2.87 mm) in the leaf methanolic extract. Synthesized AgNPs exhibited selective in vitro cytotoxicity against HEK293, HeLa, and MCF-7 cell lines. The IC50 values of the AgNPs synthesized from the various extracts were all above 9 µg/mL. Significant cytotoxic levels (IC50 16.11 and 27.23 µg/mL) were observed for the MCF-7 cell line upon exposure to the methanolic leaf and stem AgNPs. This study recommends the use of medicinal plant extracts in producing economically effective AgNPs, due to their efficient capping. Overall, AgNPs synthesized from B. albostellata extracts comprised novel antibacterial and anticancer agents, and warrant further investigation. Bio-synthesized AgNPs show great potential in the area of nanotechnology and may be used as an affordable, eco-friendly alternative for the delivery of conventional therapeutics.

Green synthesis of copper oxide nanoparticles using Ficus racemosa leaf extract and investigation of its antibacterial properties

ABSTRACT The present work reports a one-pot green synthesis of copper oxide nanoparticles (CuO NPs) using Ficus racemosa leaf extract via a green chemistry approach without using any harsh chemical reagents. The crystalline and single-phase CuO NPs were analysed via XRD. DLS revealed the average particle size distribution, and zeta potential was used for the evaluation of surface charge. Optical properties were determined at 530 nm through UV–Vis spectroscopy with a broad peak in the range from 500 to 590 nm. Different functional groups in the leaf extract containing flavonoids and polyphenols as reducing agents responsible for the synthesis of CuO NPs were verified through FTIR. The FESEM images revealed the average particle size in the range from 30 to 300 nm with a spherical morphology, and EDS was used for the quantitative elemental analysis. The strong bacterial inhibition tendency of CuO NPs against 12 bacterial strains including Bacillus cereus, Campylobacter jejuni, Bacillus subtilis, Clostridium perfringens, Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, Vibrio cholerae, Shigella dysenteriae, Listeria monocytogenes, Helicobacter pylori, and Salmonella typhi was observed with MIC values between 60 and 1000 µg/mL. The findings suggest that the synthesis of CuO NPs via green chemistry can serve as a potential substitute for traditional multi-step chemical synthetic routes.

Unveiling Hierarchical Self-Assembly of Triazolylferrocenyl Dendrimers: Producing Non-Traditional Intrinsically Green Fluorescent Vesosomes for Nanotheranostics.

Dendrimers and supramolecular chemistry continue to fascinate researchers due to the endless unrevealed potential of their combination. This study investigates the self-assembly process of a series of hydrophobic triazolylferrocenyl dendrimers in aqueous medium. Deep investigation through NMR spectroscopy, absorption UV-vis spectroscopy along with theoretical simulations demonstrates that the ferrocenyl moieties interact intramolecularly and intermolecularly driving the self-assembly process. Data obtained by DLS, NTA, SEM, TEM, and EF-TEM demonstrate that these dendrimers, in water, spontaneously self-assemble through a hierarchical process. The dendrimers first self-assemble into uniform nanovesicles, which in turn self-assemble into larger vesosomes. The resulting vesosomes emit green non-traditional intrinsic fluorescence, which is a property that emerged from the self-assembled architectures. The vesosomes are efficiently uptaken by cancer cells and induce significant cytotoxic activity against the cancer cell line MCF-7, up to the submicromolar concentration. Positive dendritic effects are identified in the fluorescence intensity and in the cytotoxic activity of the vesosomes, which follow the trend G0-9Fc < G1-27Fc < G2-81Fc. This work showcases the remarkable potential of combining the two dynamic fields of dendrimers and supramolecular chemistry, which resulted in green fluorescent vesosomes capable of performing the dual role of cell imaging and killing, with potential applications in nanotheranostics.

Biosynthesis and Characterization of Zinc Nanoparticles Using Strains of Pseudomonas and Actinobacteria

Research was carried out at the Green Nanotechnology Laboratory, University of Agricultural Sciences, Dharwad, Karnataka, with a specific emphasis on the biosynthesis of zinc nanoparticles using Pseudomonas and Actinobacteria. Collection and screening of Pseudomonas and Actinobacterial isolates were done at Microbial Genetics Laboratory, Department of Agricultural Microbiology, UAS, Dharwad. The ZnNPswere biosynthesized and characterized through UV-Visible spectroscopy, Particle Size Analyzer (PSA), Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The ZnNPs synthesized through Pseudomonas(AUDP209) and Actinobacteria(AUDT636)isolates exhibited peak values at 365 and 374 nm, with average sizes of 48.7 nm and 54.9 nm, respectively.SEM images revealed the spherical shape of the biosynthesized ZnNPs, while EDX confirmed the zinc ions presence in the biosynthesized samples and the crystalline structure of the ZnNPswas confirmed by XRD.FTIR spectroscopy confirmed the organic compounds present in the microbial extracts responsible for the capping and stabilizing agents for biosynthesis of ZnNPs.

Origin of Enhanced Oxygen Evolution in Restructured Metal-Organic Frameworks for Anion Exchange Membrane Water Electrolysis.

Metal-Organic Frameworks (MOFs), praised for structural flexibility and tunability, are prominent catalyst prototypes for exploring oxygen evolution reaction (OER). Yet, their intricate transformations under OER, especially in industrial high-current environments, pose significant challenges in accurately elucidating their structure-activity correlation. Here, we harnessed an electrooxidation process for controllable MOF reconstruction, discovering that Fe doping expedites Ni(Fe)-MOF structural evolution, accompanied by the elongation of Ni-O bonds, monitored by in-situ Raman and UV-visible spectroscopy. Theoretical modeling further reveals that Fe doping and defect-induced tensile strain in the NiO6 octahedra augments the metal ds-Op hybridization, optimizing their adsorption behavior and augmenting OER activity. The reconstructed Ni(Fe)-MOF, serving as the anode in anion exchange membrane water electrolysis, achieves a noteworthy current density of 3.3 A cm-2 at 2.2 V while maintaining equally stable operation for 160 h spanning from 0.5 A cm-2 to 1 A cm-2. This undertaking elevates our comprehension of OER catalyst reconstruction, furnishing promising avenues for designing highly efficacious catalysts across electrochemical platforms.

Photochemical Origins of Iron Flocculation in Acid Mine Drainage.

Acid mine drainage (AMD) raises a global environmental concern impacting the iron cycle. Although the formation of Fe(III) minerals in AMD-impacted waters has previously been reported to be regulated by biological processes, the role of abiotic processes remains largely unknown. This study first reported that a photochemical reaction coupled with O2 significantly accelerated the formation of Fe(III) flocculates (i.e., schwertmannite) in the AMD, as evidenced by the comparison of samples from contaminated sites across different natural conditions at latitudes 24-29° N. Combined with experimental and modeling results, it is further discovered that the intramolecular oxidation of photogenerated Fe(II) with a five-coordinative pyramidal configuration (i.e., [(H2O)5Fe]2+) by O2 was the key in enhancing the photooxidation of Fe(II) in the simulated AMD. The in situ attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR), UV-vis spectroscopy, solvent substitution, and quantum yield analyses indicated that, acting as a precursor for flocculation, [(H2O)5Fe]2+ likely originated from both the dissolved and colloidal forms of Fe(III) through homogeneous and surface ligand-to-metal charge transfers. Density functional theory calculations and X-ray absorption spectroscopy results further suggested that the specific oxidation pathways of Fe(II) produced the highly reactive iron species and triggered the hydrolysis and formation of transient dihydroxo dimers. The proposed new pathways of Fe cycle are crucial in controlling the mobility of heavy metal anions in acidic waters and enhance the understanding of complicated iron biochemistry that is related to the fate of contaminants and nutrients.

Wavy Graphene Nanoribbons Containing Periodic Eight-Membered Rings for Light-Emitting Electrochemical Cells.

Precision graphene nanoribbons (GNRs) offer distinctive physicochemical properties that are highly dependent on their geometric topologies, thereby holding great potential for applications in carbon-based optoelectronics and spintronics. While the edge structure and width control has been a popular strategy for engineering the optoelectronic properties of GNRs, non-hexagonal-ring-containing GNRs remain underexplored due to synthetic challenges, despite offering an equally high potential for tailored properties. Herein, we report the synthesis of a wavy GNR (wGNR) embedding periodic eight-membered rings into its carbon skeleton, which is achieved by the A2B2-type Diels-Alder polymerization between dibenzocyclooctadiyne (6) and dicyclopenta[e,l]pyrene-5,11-dione derivative (8), followed by a selective Scholl reaction of the obtained ladder-type polymer (LTP) precursor. The obtained wGNR, with a length of up to 30 nm, is thoroughly characterized by solid-state NMR, FT-IR, Raman, and UV-Vis spectroscopy with the support of DFT calculations. The non-planar geometry of wGNR efficiently prevents the inter-ribbon π-π aggregation, leading to photoluminescence in solution. Consequently, the wGNR can function as an emissive layer for organic light-emitting electrochemical cells (OLECs), offering a proof-of-concept exploration in implementing luminescent GNRs into optoelectronic devices. The fast-responding OLECs employing wGNR will pave the way for advancements in OLEC technology and other optoelectronic devices.

Solar Light CO2 Photoreduction Enhancement by Mononuclear Rhenium(I) Complexes: Characterization and Mechanistic Insights.

The catalytic efficacy of a novel mononuclear rhenium(I) complex in CO2 reduction is remarkable, with a turnover number (TONCO) of 1517 in 3 h, significantly outperforming previous Re(I) catalysts. This complex, synthesized via a substitution reaction on an aromatic ring to form a bromo-bipyridine derivative, L1 = 2-bromo-6-(1H-pyrazol-1-yl)pyridine, and further reacting with [Re(CO)5Cl], results in the facial-tricarbonyl complex [ReL1(CO)3Cl] (1). The light green solid was obtained with an 80% yield and thoroughly characterized using cyclic voltammetry, nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy. Cyclic voltammetry under CO2 atmosphere revealed three distinct redox processes, suggesting the formation of new electroactive compounds. The studies on photoreduction highlighted the ability of the catalyst to reduce CO2, while NMR, FTIR, and electrospray ionization (ESI) mass spectrometry provided insights into the mechanism, revealing the formation of solvent-coordinated complexes and new species under varying conditions. Additionally, computational studies (DFT) were undertaken to better understand the electronic structure and reactivity patterns of 1, focusing on the role of the ligand, the spectroscopic features, and the redox behavior. This comprehensive approach provides insights into the intricate dynamics of CO2 photoreduction, showcasing the potential of Re(I) complexes in catalysis.

Gate modulation of barrier height of unipolar vertically stacked monolayer ReS2/MoS2 heterojunction

This study investigates vertically stacked CVD grown ReS2/MoS2 unipolar heterostructure device as Field Effect Transistor (FET) device wherein ReS2 on top acts as drain and MoS2 at bottom acts as source. The electrical measurements of ReS2/MoS2 FET device were carried out and variation in Ids (drain current) Vs Vds (drain voltage) for different Vgs (gate voltage) revealing the n-type device characteristics. Furthermore, the threshold voltage was calculated at the gate bias voltage corresponding to maximum transconductance (gm) value which is ~ 12 V. The mobility of the proposed ReS2/MoS2 heterojunction FET device was calculated as 60.97 cm2 V−1 s−1. The band structure of the fabricated vDW heterostructure was extracted utilizing ultraviolet photoelectron spectroscopy and the UV–visible spectroscopy revealing the formation of 2D electron gas (2DEG) at the ReS2/MoS2 interface which explains the high carrier mobility of the fabricated FET. The field effect behavior is studied by the modulation of the barrier height across heterojunction and detailed explanation is presented in terms of the charge transport across the heterojunction.

Surface-enhanced Raman scattering enhancement using a hybrid gold nanoparticles@carbon nanodot substrate for herbicide detection.

The widespread distribution of herbicides in the environment poses a significant risk to human health and wildlife. Surface-enhanced Raman scattering (SERS) has emerged as a powerful technique for detecting and analyzing herbicides. However, developing a low-cost, highly sensitive, reproducible, stable, and Raman-active nanostructured substrate for herbicide detection remains a particular challenge. In this research, a nanohybrid substrate consisting of gold nanoparticles@carbon nanodots (AuNPs@CNDs) was synthesized by reducing HAuCl4 in the presence of CNDs at 100 °C. The optical, chemical, and physical properties of CNDs, AuNPs, and the hybrid AuNPs@CND substrates were thoroughly investigated using various techniques including UV-vis spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and CytoViva darkfield and hyperspectral imaging. The SERS effect of the substrates was evaluated using rhodamine 6G (Rh6G), a Raman-active probe, and two groups of herbicides containing mesotrione or S-metolachlor. The results demonstrated a significant signal amplification in the SERS spectra of Rh6G and herbicide molecule detection using the AuNPs@CND substrate compared to bare CNDs and AuNPs alone. This suggests that the nanohybrid AuNPs@CND SERS substrate holds promise for the detection of herbicides and other organic compounds in environmental applications.

Enabling highly efficient navy-blue dye degradation over the LaFeO3/B-g-C3N4/WO3 double z-scheme heterostructure

Chemical reactivity, optical and electronic features of conventional photocatalysts can be improved by chemical modification and nanocomposites fabrication techniques. Herein, a double Z-scheme LaFeO3/B-g-C3N4/WO3 (LFO/B-CN/WO) heterostructure nanocomposite has been successfully fabricated via a hydrothermal approach. XRD, FT-IR, SEM/EDS, TEM, TGA/DSC, and UV–visible spectroscopy confirmed crystallographic planes, phase purity, and heterojunction between LFO, WO and B-CN. From UV visible absorption spectroscopy, it was confirmed that optical band gap energy of CN is remarkably reduced after boron doping. The LFO/B-CN/WO photocatalyst revealed 96 % degradation performance for Navy Blue (NB) dye after visible light irradiation for 130 min under neutral pH conditions. The data were analyzed using pseudo-first and pseudo-second order kinetics models to evaluate the dye degradation kinetics. Compared to the CN, B-CN, LFO-CN and WO-CN photocatalysts, the performance of LFO/B-CN/WO was much significant. Improved light absorption capability, effective spatial separation and prolonged charge-carrying capacity of the double Z-scheme system resulted in enhanced photocatalytic performance. This study offers new insights into the design and synthesis of highly efficient Z-scheme heterojunction photocatalysts for environmental decontamination and clean energy purposes.

Isolation of Elusive Fluoflavine Radicals in Two Differing Oxidation States.

Facile access and switchability between multiple oxidation states are key properties of many catalytic applications and spintronic devices yet poorly understood due to inherent complications arising from isolating a redox system in multiple oxidation states without drastic structural changes. Here, we present the first isolable, free fluoflavine (flv) radical flv(1-•) as a bottleable potassium compound, [K(crypt-222)](flv•), 1, and a new series of organometallic rare earth complexes [(Cp*2Y)2(μ-flvz)]X, (where Cp* = pentamethylcyclopentadienyl, X = [Al(OC{CF3}3)4]- (z = -1), 2; X = 0 (z = -2), 3; [K(crypt-222)]+ (z = -3), 4) comprising the flv ligand in three different oxidation states, two of which are paramagnetic flv1-• and flv3-•. Excitingly, 1, 2, and 4 constitute the first isolable flv1-• and flv3-• radical complexes and, to date, the only isolated flv radicals of any oxidation state. All compounds are accessible in good crystalline yields and were unambiguously characterized via single-crystal X-ray diffraction analysis, cyclic voltammetry, IR-, UV-vis, and variable-temperature EPR spectroscopy. Remarkably, the EPR spectra for 1, 2, and 4 are distinct and a testament to stronger spin delocalization onto the metal centers as a function of higher charge on the flv radical. In-depth analysis of the electron- and spin density via density functional theory (DFT) calculations utilizing NLMO, QTAIM, and spin density topology analysis confirmed the fundamental interplay of metal coordination, ligand oxidation state, aromaticity, covalency, and spin density transfer, which may serve as blueprints for the development of future spintronic devices, single-molecule magnets, and quantum information science at large.

Interactions of human serum albumin with phosphate and Tris buffers: impact on paclitaxel binding and nanoparticles self-assembly

Aim To investigate the conformational changes in human serum albumin (HSA) caused by chemical (CD) and thermal denaturation (TD) at pH 7.4 and 9.9, crucial for designing controlled drug delivery systems with paclitaxel (PTX). Methods Experimental and computational methods, including differential scanning calorimetry (DSC), UV-Vis and intrinsic fluorescence spectroscopy, mean diameter, polydispersity index (PDI), ζ-potential, encapsulation efficiency (EE), in vitro release and protein docking studies were conducted to study the HSA denaturation and nanoparticles (NPs) preparation. Results TD at pH 7.4 produced smaller NPs (287.1 ± 12.9 nm) than CD at pH 7.4 with NPs (584.2 ± 47.7 nm). TD at pH 9.9 exhibited high EE (97.3 ± 0.2%w/w) with rapid PTX release (50% within 1h), whereas at pH 7.4 (96.4 ± 2.1%w/w), release only 40%. ζ-potentials were around −30 mV. Conclusion Buffer type and pH significantly influence NP properties. TD in PBS at pH 7.4, provided optimal conditions for a stable and efficient drug delivery system.

Role of hydroxyl groups in Zn-containing nanosized MFI zeolite for the photocatalytic oxidation of methane.

Effective conversion of methane to a mixture of more valuable hydrocarbons and hydrogen under mild conditions is a great scientific and practical challenge. Here, we synthesized Zn-containing nanosized MFI zeolite for direct oxidation of methane in the presence of H2O and air. The presence of the surface hydroxyl groups on nanosized MFI-type zeolite and their significant reduction in the Zn-containing nanosized MFI zeolite were confirmed with Infrared Fourier Transform (FTIR) spectroscopy. Incorporation of zinc atoms into the framework of nanosized MFI zeolite is revealed by Nuclear Magnetic Resonance, X-ray Diffraction a UV-Vis Spectroscopy. Unexpectedly, pure silica MFI zeolite exhibited the highest photocatalytic performance. Our finds demonstrated that large number of isolated silanol groups and silanol nests increase the formation of •OH, and enhance the productivity of oxygenate compounds and C2H6, while the Zn incorporated into the zeolite framework or attached to the silanol nests of the nanosized zeolites are less efficient. A mechanism of photocatalytic methane oxidation is proposed. These findings provide insights into developing active nanosized zeolite photocatalysts with extended amount of surface hydroxyl groups that can play a key role in photocatalytic methane conversion.