Red-shifted Absorption Spectra Research Articles

TVT-Based New Building Block with Enhanced π-Electron Delocalization for Efficient Non-Fused Photovoltaic Acceptor.

To address the high-cost issue that impedes the large-scale fabrication and industrialization of organic solar cells (OSCs), it is crucial to design low-cost photovoltaic materials with simplified synthesis procedures. In this study, a novel fully non-fused acceptor, ATVT-BO, featuring a triisopropylbenzene-substituted (E)-1,2-di(thiophen-2-yl)ethene (TVT) unit as the central core is designed and synthesized. A control acceptor, A4T-BO, with the same alkyl chains but a bithiophene central core, is also synthesized for comparison. Theoretical calculations and practical measurements reveal that compared to A4T-BO, the insertion of an ethylene bond in ATVT-BO enhances the molecular planarity and reduces the aromaticity, leading to enhanced π-electron delocalization and thus improved electron mobility and a red-shifted optical absorption spectrum. The 3D molecular packing mode of ATVT-BO, characterized by tight intermolecular interactions, also promotes efficient charge transport in OSCs. Consequently, when paired with the low-cost polymer PTVT-T, featuring an ester-substituted TVT structure, as the photoactive layer, the PTVT-T:ATVT-BO-based device achieves a remarkable power conversion efficiency of 14.8%, distinctly higher than that of PTVT-T:A4T-BO-based cell. The result highlights the significant potential of TVT units in creating both low-cost polymer donors and fully non-fused acceptors, which opens up new possibilities for designing low-cost photoactive materials in OSCs.

Breaking New Grounds: solid-state synthesis of TiO2 – La2O3 – CuO Nanocomposites for degrading Brilliant Green dye under Visible Light

Environmental pollution, particularly from industrial dyes and chemicals, poses a significant threat to ecosystems and human health. Traditional pollution mitigation methods are often inefficient and costly. Photocatalysis has emerged as a promising solution for degrading pollutants using light energy. Titanium dioxide (TiO2) is a widely studied photocatalyst due to its stability, non-toxicity, and strong oxidative power. However, its efficiency is limited by a wide bandgap, restricting absorption to the UV region, and rapid electron-hole recombination. To address these limitations, doping TiO2 with materials like La2O3 and CuO has been explored to enhance its photocatalytic activity under visible light. This study investigates the enhancement of TiO2 nanocomposites by incorporating La2O3 and CuO. X-ray diffraction (XRD) revealed that the nanocomposites retained TiO2's anatase and rutile phases with improved crystallinity. Scanning electron microscopy (SEM) displayed spherical nanoparticles forming agglomerates, typically due to high surface energy. Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of La and Cu in the TiO2 matrix. Fourier-transform infrared (FTIR) spectroscopy identified characteristic vibrational modes of Ti–O, La–O, and Cu–O bonds, suggesting strong chemical interactions between dopants and TiO2 lattice. Ultraviolet-visible (UV-Vis) spectroscopy showed a red shift in absorption spectra with La2O3 and CuO addition, reducing the bandgap energy from 3.23 eV (pure TiO2) to 2.27 eV for the TiO2–0.1La2O3–0.2CuO composite. Photoluminescence (PL) spectroscopy indicated improved charge separation and reduced electron-hole recombination rates in the synthesized nanocomposites. Photocatalytic performance was evaluated by degrading Brilliant Green (BG) dye under visible light. The TiO2–0.1La2O3–0.2CuO (TLC0.2) nanocomposite achieved a maximum dye degradation of over 95% after 204 minutes under optimal conditions (C0 = 17 mg/L and a S/L ratio of 1 g/L). Adding the inorganic agent Na2SO4 to this process significantly enhanced photocatalytic activity, increasing degradation from 56% to 95% after 180 min of visible light irradiation under C0 = 20 mg/L and S/L = 0.5 g/L conditions, as it shows a high stability after six reuse cycles. In conclusion, La2O3 and CuO doping significantly enhance TiO2 nanocomposites' crystalline structure, morphology, optical properties, and photocatalytic efficiency, demonstrating their potential for environmental remediation and solar energy conversion.

Enhanced optical, dielectric and transport properties in PVDF based (La0.5Bi0.5FeO3)0.5-(BaTiO3)0.5 composites

In this comprehensive study, we investigated PVDF composites incorporating LaBiFeO3-BaTiO3 (LaBiFO-BaTO) perovskite fillers, focusing on their structural, optical, dielectric, impedance, modulus and DC-conductivity properties. The fabrication involved precise preparation of LaBiFO-BaTO perovskite via solid-state reaction, ensuring phase purity conducive to composite integration. Using a solution casting method, PVDF films with varying LaBiFO-BaTO concentrations (5 %, 10 %, and 15 % wt) were successfully synthesized. XRD confirmed the synthesis of single-phase LaBiFO-BaTO and revealed structural modifications in PVDF composites, highlighting improved filler-matrix interactions at higher concentrations. Scanning electron microscopy and atomic force microscopy depicted the morphological evolution and surface roughness changes with increasing filler content. Optical studies indicated a red shift in absorption spectra with higher LaBiFO-BaTO concentrations, correlating with a decrease in the direct band gap energy of the composites. Electrical characterization demonstrated enhanced dielectric properties and impedance behaviour in PVDF/LaBiFO-BaTO composites, suggesting their suitability for applications in capacitors and optoelectronic devices. This systematic investigation provides valuable insights into optimizing PVDF-based composites for advanced functional materials. The composites exhibit enhanced dielectric permittivity at room temperature, attributed to space charge polarization and the high dielectric constant of LaBiFO-BaTO. Dielectric loss (tanδ) remains minimal (<0.1), decreasing with frequency, indicative of low energy dissipation suitable for high-frequency applications. Further the dielectric relaxation have been examined using Havrilak-Negami model. Impedance and modulus analyses reveal temperature-dependent behaviours, with reduced impedance and enhanced charge transfer kinetics in higher concentration composites. DC conductivity measurements demonstrate increased charge transport properties with temperature, influenced by thermally activated charge hopping mechanisms. Overall, PVDF/LaBiFO-BaTO composites show promising characteristics for capacitors, sensors, and optoelectronic devices, suggesting avenues for further optimization and broader application in advanced technologies.

Heterojunction Organic Solar Cells with Efficient Charge Mobility and Separation Capabilities Studied by DFT.

The properties of the active layer materials play a decisive role in determining the power conversion efficiency of organic solar cells (OSCs). Chlorophyll and its derivatives are abundant and environmentally friendly functional organic molecular materials. Using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), we have calculated the absorption spectra and their excited state properties based on optimized ground state structures. It was found that bacteriochlorin exhibits superior structural properties, a smaller energy gap and hole reorganization energy, redshifted absorption spectra, and higher hole mobility compared to the donor D18. This suggests that bacteriochlorin exhibits superior donor properties. Comparative studies between o-AT-2Cl and m-AT-2Cl showed that o-AT-2Cl had superior acceptor properties, implying that differences in substitution positions can influence the physicochemical properties of non-fullerene acceptors (NFAs). Subsequently, six bulk heterojunctions (BHJs) were constructed by combining three donors with nonfused ring electron acceptors, o-AT-2Cl and m-AT-2Cl. The bacteriochlorin-based BHJs performed well among them, with BChl3/o-AT-2Cl and BChl4/o-AT-2Cl having the largest interfacial charge separation rate. The results suggested that BHJs composed of bacteriochlorin and NFAs can improve OSCs' photovoltaic performance, providing a feasible scheme for designing efficient OSCs.

Adjustable Regioselectivity for the Diels-Alder Reactions of Sulfolenodipyrrins upon Molecular Engineering on H-Bonds.

The Diels-Alder reactions of sulfolenodipyrrins prove to be an efficient way to construct aromatic ring-fused dipyrrins. However, adjustable annulation is still hard to achieve. To address this, molecular engineering on the H-bond has been employed. The α-position aryl group-modified sulfolenodipyrrins have been synthesized to react with various dienophiles in Diels-Alder reactions, affording the monoannulation products with different regioselectivity in good yields (45-76%). The remaining sulfolenopyrrole in monoadducts can undergo further fusion in the presence of dienophiles and TEMPO, giving the bisadducts with a lactam subunit in an appropriate yield. According to the crystal structures and theoretical calculations, the intramolecular H-bonds between the α-substituent and the nearby pyrrole confine the conjugation pathway of the dipyrrin core. With respect to the normal NH-sulfolenopyrrole, the imino-type one features low aromaticity, from which SO2 extrusion generates more stable dipyrrin-diene, achieving regioselectivity. In addition, aromatic ring fusion results in red-shifted absorption and emission spectra, and the annulation units regulate the emission intensity. This work shows the versatility of intramolecular H-bonds in regulating the reaction through confinement of the conjugation system.

How to choose proper electron acceptor groups for highly efficient copper electrolyte-based dye-sensitized solar cells?

A better understanding of electron-accepting groups (EAGs) is important for the development of potentially efficient dyes. Density functional theory (DFT) and time-dependent DFT were employed in this study to investigate a variety of dyes derived from XY1b (11.8 %) in conjunction with prominent EAGs including 2-cyano-3-phenylacrylic acid (CPA), 2-cyano-acrylic acid (CA), and benzoic acid (BA). Various critical parameters pertaining to short-circuit current density (Jsc) and open-circuit photovoltage (Voc) were calculated, including light-harvesting ability, conduction band energy shift, dye-[Cu(tmby)2]2+ interaction, dye aggregation, and charge recombination, in order to illustrate the advantages and limitations of these EAGs. The findings indicate that dyes based on CA demonstrate a redshifted absorption spectrum, stronger electronic coupling with TiO2 conduction band, extended excited state lifetime, and enhanced dye regeneration driving force, resulting in higher Jsc compared to CPA and BA-based dyes. Regarding Voc, CA-based dyes show an increased conduction band energy shift due to their larger vertical dipole moment and reduced charge recombination with [Cu(tmby)2]2+. Additionally, it is suggested that future studies on structure–property relationships should prioritize identifying the optimal dye conformation, as it significantly influences adsorption configuration and vertical dipole moment. Overall, among the commonly utilized EAGs, CA stands out for its ability to enhance Jsc, Voc, and adsorption stability over CPA and BA-based dyes.

Impact of Alkoxy Side Chains on the Quinoxaline-Based Electron Acceptors for Efficient Organic Solar Cells.

In this work, three alkoxy-substituted quinoxaline core-based small-molecule acceptors (BQO-F, BQDO-F, and BQDO-Cl) are developed to elucidate the impact of ethoxy substituents on the physicochemical and photoelectric properties. Comparative analysis reveals that dialkoxy-substituted BQDO-F has a more planar molecular skeleton, a red-shifted absorption spectrum, upshifted energy levels, stronger crystallinity, and reduced energetic disorder compared to the monoalkoxy-substituted BQO-F. Although the replacement of fluorine atoms with chlorine atoms on the end-capped units of BQDO-F leads to a bathochromically shifted absorption spectrum, the resulting molecule BQDO-Cl shows worse π-π packing order compared to BQDO-F. Benefiting from the more favorable active layer morphology and improved carrier dynamics, the PBDB-T:BQDO-F-based organic solar cell achieves a much higher power conversion efficiency (PCE) of 16.41% compared to that of 14.48% obtained in the BQO-F-based device. In comparison with the BQDO-F-based device, the higher voltage loss of the BQDO-Cl-based device results in a lower PCE of 15.89%. The results clarify the effects of ethoxy substituents and end-capped substitutions of quinoxaline core-based small-molecule acceptors on efficient organic solar cells.

DFT/TD-DFT study of novel triphenylamine-based dyes with azo moieties and π-spacer variations for enhanced dye-sensitized solar cell performance

This study involves a computational analysis of new D-π-A dyes obtained from triphenylamine (TPA), which contain various azo-dye components. The structural, molecular, electrical, and optical properties of these dyes were computed using Density Functional Theory (DFT) and Time-Dependent DFT, utilizing the B3LYP/6–31 G model. Our research specifically aimed to investigate the effects of incorporating different azo dye constituents in the para position of two phenyl groups of TPA. The results indicate that these alterations lead to notably broadened and red-shifted absorption spectra, as well as improved optoelectronic properties that are subject to additional tuning through the manipulation of the π-spacer. The excitation energies and HOMO-LUMO energy levels that have been estimated indicate the presence of effective electron injection and dye regeneration mechanisms. The results concerning the nonlinear optical (NLO) properties suggest that these dyes are likely to demonstrate superior performance in NLO applications. The factors encompassed in this study consist of light-harvesting efficiency (LHE), open-circuit photovoltage (VOC), electron injection driving force (ΔGinj), dye regeneration driving force (ΔGreg), excited state lifetime (τ) and reorganization energy (λtotal), which has a strong correlation with the electrical current density in a short-circuit (JSC) and DSSC's overall effectiveness. This scientific attempt contributes to the systematic advancement of efficient dyes, demonstrating the possibility for enhanced efficiency in DSSCs. Further validation of computational forecasts and advancement of renewable energy technology necessitate future experimental synthesis and testing.

Methyl- and fluoro-substituted triphenylamine core toward fast-switching visible and near-infrared electrochromic polymers

Herein, two monomers MTPA and FTPA, and their corresponding polymers (PMTPA and PFTPA) based on a methyl-and fluoro-substituted triphenylamine were synthesized by Stille reaction and electropolymerization. MTPA exhibited the red-shift absorption and fluorescence emission spectra, and lower Eonset (0.53 V) compared with FTPA (0.57 V), which is beneficial to achieve high-quality polymers. The polymer films exhibited reversible color transition from yellow green to deep blue for PMPTA and from dark brown to light blue for PFTPA, respectively. In addition, both PMTPA and PFTPA films exhibited good optical contrasts of 36 % and 40 % at 1100 nm, respectively. The coloration efficiency and response times at 1100 nm are 196.4 C−1 cm2 with 0.6 s for PMTPA, and 160.9 C−1 cm2 with 1.4 s for PFTPA, respectively. These polymer films demonstrated excellent electrochemical property and electrochromic performance. These results will also provide a new strategy to rationally design the excellent electrochromic polymers based on the triphenylamine core.

Impact of hydrolysis on the quantification of sulfonated acrylamide copolymers by size exclusion chromatography with UV detection

AbstractSize exclusion chromatography with UV detection (SEC‐UV) is a precise method for quantifying polyacrylamides in water. However, its accuracy can be compromised in complex matrices due to chemical degradation of the polymer. This study focuses on the impact of hydrolysis on quantifying sulfonated polyacrylamide copolymers (PAM‐AMPS) via SEC‐UV, analyzing key influencing factors. Using controlled hydrolysis, hydrolyzed copolymer (HPAM‐AMPS) standards with varying hydrolysis degree (HD) (HD = 7%–33%) were prepared without significant changes in polymer chain size. SEC‐UV analysis revealed that quantification accuracy is highly dependent on hydrolysis extent. Errors are minimal for HD up to 10%, but significantly higher for HDs of 22%–33%. Furthermore, this effect is modulated by polymer concentration. Our findings indicate that there are two compensating factors for the decrease in molar absorptivity due to amide‐to‐carboxylate substitution: the sulfonate group acting as an additional chromophore, and a redshift in absorption spectra due to hydrogen bonding at higher concentrations. This interplay between HD and concentration in this type of sulfonated polyacrylamide can help reduce quantification errors in complex aqueous samples prone to chemical degradation, like those found in environmental and subsurface applications.

Highly efficient and stable binary and ternary organic solar cells using polymerized nonfused ring electron acceptors.

This study reports the successful design and synthesis of two novel polymerized nonfused ring electron acceptors, P-2BTh and P-2BTh-F, derived from the high-performance nonfused ring electron acceptor, 2BTh-2F. Prepared via Stille polymerization, these polymers feature thiophene and fluorinated thiophene as π-bridge units. Notably, P-2BTh-F, with difluorothiophene as the π-bridge, exhibits a more planar backbone and red-shifted absorption spectrum compared with P-2BTh. When employed in organic solar cells (OSCs) with PBDB-T as the donor material, P-2BTh-F-based devices demonstrate an outstanding power conversion efficiency (PCE) of over 11%, exceeding the 8.7% achieved by P-2BTh-based devices. Furthermore, all-polymer solar cells utilizing PBDB-T:P-2BTh-F exhibit superior storage stability. Additionally, P-2BTh-F was explored as a functional additive in a high-performance binary system, enhancing stability while maintaining comparable PCE (19.45%). This strategy offers a cost-effective approach for fabricating highly efficient and stable binary and ternary organic solar cells, opening new horizons for cost-effective and durable solar cell development.

Emissive Guanosine Analog Applicable for Real-Time Live Cell Imaging.

A new emissive guanosine analog CF3thG, constructed by a single trifluoromethylation step from the previously reported thG, displays red-shifted absorption and emission spectra compared to its precursor. The impact of solvent type and polarity on the photophysical properties of CF3thG suggests that the electronic effects of the trifluoromethyl group dominate its behavior and demonstrates its susceptibility to microenvironmental polarity changes. In vitro transcription initiations using T7 RNA polymerase, initiated with CF3thG, result in highly emissive 5'-labeled RNA transcripts, demonstrating the tolerance of the enzyme toward the analog. Viability assays with HEK293T cells displayed no detrimental effects at tested concentrations, indicating the safety of the analog for cellular applications. Live cell imaging of the free emissive guanosine analog using confocal microscopy was facilitated by its red-shifted absorption and emission and adequate brightness. Real-time live cell imaging demonstrated the release of the guanosine analog from HEK293T cells at concentration-gradient conditions, which was suppressed by the addition of guanosine.

Design and synthesis of fluorescent BODIPY derivatives with D-A structure for cancer cell imaging

Boron-dipyrromethene (BODIPY) as a traditional fluorescent dye has received increasing attention because of its high molar extinction coefficient, easy modification, and good light stability. In this work, three BODIPY compounds (BDP-1, BDP-2 and BDP-3) were designed and synthesized by introducing PEG chains and a naphthalimide (NI) group onto the parent structure of BODIPY. Due to the electron-withdrawing properties of NI, the compounds of BDP-2 and BDP-3 formed a typical donor (D)-acceptor (A) structure, which led to the red-shifted absorption and fluorescence spectrum. The synthesized BODIPY exhibited intense green emission, with fluorescence quantum yield of 0.66, 0.29, and 0.19 for BDP-1, BDP-2 and BDP-3 respectively. The decrease in fluorescence of BDP-2 and BDP-3 was probably ascribed to the enhanced intramolecular charge transfer because of the introduction of the NI group. The good biocompatibility and low cytotoxicity of the synthesized BODIPY compounds were verified by the CCK-8 assay. The subcellular localization of the three compounds was further evaluated through a confocal laser scanning microscope. The results showed that these BODIPY derivatives were mainly localized in the lysosomes of cancer cells. Thus, the synthesized BODIPY fluorescent dyes show promising applications in tumor imaging benefiting from their good biocompatibility and strong fluorescence.

Thio and Seleno-Psoralens as Efficient Triplet Harvesting Photosensitizers for Photodynamic Therapy.

The Psoralen (Pso) molecule finds extensive applications in photo-chemotherapy, courtesy of its triplet state forming ability. Sulfur and selenium replacement of exocyclic carbonyl oxygen of organic chromophores foster efficient triplet harvesting with near unity triplet quantum yield. These triplet-forming photosensitizers are useful in Photodynamic Therapy (PDT) applications for selective apoptosis of cancer cells. In this work, we have critically assessed the effect of the sulfur and selenium substitution at the exocyclic carbonyl (TPso and SePso, respectively) and endocyclic oxygen positions of Psoralen. It resulted in a significant redshifted absorption spectrum to access the PDT therapeutic window with increased oscillator strength. The reduction in singlet-triplet energy gap and enhancement in the spin-orbit coupling values increase the number of intersystem crossing (ISC) pathways to the triplet manifold, which shortens the ISC lifetime from 10-5 s for Pso to 10-8 s for TPso and 10-9 s for SePso. The intramolecular photo-induced electron transfer process, a competitive pathway to ISC, is also considerably curbed by exocyclic functionalizations. In addition, a maximum of 115 GM of two-photon absorption (2PA) with IR absorption (660-1050 nm) confirms that the Psoralen skeleton can be effectively tweaked via single chalcogen atom replacement to design a suitable PDT photosensitizer.

An environmentally-friendly approach to monovalent Cu-doped ZnS: Physicochemical characterization and photocatalytic activity

Certain semiconducting species suffer from the lack of optical activity in the visible region of electromagnetic spectrum, due to large band gap. The integration of various dopants has been widely used in order to generate additional electron transitions and subsequently lead to red-shifted absorption spectrum and enhanced photon harvesting in the visible-NIR region. Herein, a facile two-step environmentally-friendly approach was employed to integrate monovalent Cu species onto ZnS lattice. The study was set to assess the effect of Cu doping in Zinc Sulfide lattice on optical and photocatalytic properties. The theoretical weight fraction of the dopant ranged between 0% and 50%. The physicochemical characterization of either neat semiconductors (ZnS and Cu2O) or Cu-doped ZnS hybrids was performed by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman, X-ray photoelectron spectroscopy (XPS), X-ray induced Auger electron spectroscopy (XAES) and Diffuse reflectance spectroscopy (DRS). XPS provided some enhanced understanding about the chemical speciation of the hybrid materials. This information was strongly supported by Raman analysis. The optimized Cu-doped ZnS hybrid demonstrated enhanced photocatalytic activity towards the degradation of Orange G dye, under UV irradiation.

Alared: Solvatochromic and Fluorogenic Red Amino Acid for Ratiometric Live-Cell Imaging of Bioactive Peptides.

To fill the need for environmentally sensitive fluorescent unnatural amino acids able to operate in the red region of the spectrum, we have designed and synthesized Alared, a red solvatochromic and fluorogenic amino acid derived from the Nile Red chromophore. The new unnatural amino acid can be easily integrated into bioactive peptides using classical solid-phase peptide synthesis. The fluorescence quantum yield and the emission maximum of Alared-labeled peptides vary in a broad range depending on the peptide's environment, making Alared a powerful reporter of biomolecular interactions. Due to its red-shifted absorption and emission spectra, Alared-labeled peptides could be followed in living cells with minimal interference from cellular autofluorescence. Using ratiometric fluorescence microscopy, we were able to track the fate of the Alared-labeled peptide agonists of the apelin G protein-coupled receptor upon receptor activation and internalization. Due to its color-shifting environmentally sensitive emission, Alared allowed for distinguishing the fractions of peptides that are specifically bound to the receptor or unspecifically bound to different cellular membranes.

A Visual Raman Nano-Delivery System Based on Thiophene Polymer for Microtumor Detection.

A visual Raman nano-delivery system (NS) is a widely used technique for the visualization and diagnosis of tumors and various biological processes. Thiophene-based organic polymers exhibit excellent biocompatibility, making them promising candidates for development as a visual Raman NS. However, materials based on thiophene face limitations due to their absorption spectra not matching with NIR (near-infrared) excitation light, which makes it difficult to achieve enhanced Raman properties and also introduces potential fluorescence interference. In this study, we introduce a donor-acceptor (D-A)-structured thiophene-based polymer, PBDB-T. Due to the D-A molecular modulation, PBDB-T exhibits a narrow bandgap of Eg = 2.63 eV and a red-shifted absorption spectrum, with the absorption edge extending into the NIR region. Upon optimal excitation with 785 nm light, it achieves ultra-strong pre-resonant Raman enhancement while avoiding fluorescence interference. As an intrinsically sensitive visual Raman NS for in vivo imaging, the PBDB-T NS enables the diagnosis of microtumor regions with dimensions of 0.5 mm × 0.9 mm, and also successfully diagnoses deeper tumor tissues, with an in vivo circulation half-life of 14.5 h. This research unveils the potential application of PBDB-T as a NIR excited visual Raman NS for microtumor diagnosis, introducing a new platform for the advancement of "Visualized Drug Delivery Systems". Moreover, the aforementioned platform enables the development of a more diverse range of targeted visual drug delivery methods, which can be tailored to specific regions.

Anisotropic Cu2O nanostructures: A promising remediation for per- and polyfluoroalkyl substances

Copper oxide (Cu2O) exhibits exceptional optical properties and phase stability at the nanoscale level making it highly desirable in nanotechnology applications. Its unique and distinctive properties make it highly feasible for diverse applications, which include environmental remediation, energy conversion, and catalysis. In this study, we tailor the surface and facet orientation of Cu2O nanoparticles to enhance their efficacy in addressing environmental contaminants such as per- and polyfluorinated substances (PFAS). By adjusting the ratios of the precursor and capping agent, we have synthesized Cu2O nanocubes (NCs) and octahedra (Oh) with average sizes of 450 nm and 650 nm, respectively. The time-dependent UV–Vis interaction studies revealed significant redshifts in absorption spectra upon the addition of Cu2O NCs and Oh to the PFAS solutions, indicative of the changes in the surroundings upon the interaction. FT-IR spectra further confirmed the sorption of PFAS on Cu2O nanostructures with stronger adsorption observed for longer-chain PFAS due to enhanced hydrophobic interactions. XPS analysis further provided insights into the surface composition changes after post-interaction, indicating the presence of PFAS on Cu2O nanostructures. The zeta potential analysis supported the role of electrostatic interactions in PFAS removal. Our results demonstrate that Cu2O Oh exhibits superior PFAS adsorption compared to Cu2O NCs, which is attributed to the exposed facets of a copper atom having a positive surface charge and facilitating electrostatic interactions. Specifically, Cu-terminated (110) or (111) surfaces exhibit enhanced sorption capacity, while the reduced reactivity of Cu-terminated Cu2O (100) surfaces is linked to high energy barrier holes at the surface region. Overall, this study elucidates the interaction mechanisms between Cu2O nanostructures and PFAS which underscores the significance of surface engineering for optimizing their performance in environmental remediation strategies.

A DFT/TD-DFT Study of the Influence of Anchoring Group and Internal Acceptor of Benzocarbazole-based D-A´-π-A Dyes for DSSCs

Great attention is being shifted to Dye-sensitized solar cells because of their structural and electronic tunability, high performance, and low cost compared to conservative photovoltaic devices. In this work, the DFT/B3LYP/6-31G(d,p) and TD-DFT/mPW9PW91/6-31G(d,p) levels of theory are applied to the theoretical study of a new class of benzocarbazole-based D-A´-π-A dyes for their potential use in DSSCs. The influence of the internal acceptor on the optoelectronic properties is studied for the dyes. The optoelectronic and photovoltaic properties as HOMO, LUMO, E&amp;lt;sub&amp;gt;gap&amp;lt;/sub&amp;gt; maximum absorption wavelength (λ&amp;lt;sub&amp;gt;max&amp;lt;/sub&amp;gt;), vertical excitation energies (E&amp;lt;sub&amp;gt;ex&amp;lt;/sub&amp;gt;), oscillator strength (&amp;lt;i&amp;gt;f&amp;lt;/i&amp;gt;), light harvesting efficiency (LHE), open circuit voltage (V&amp;lt;sub&amp;gt;oc&amp;lt;/sub&amp;gt;), injection force (ΔG&amp;lt;sub&amp;gt;inject)&amp;lt;/sub&amp;gt;, were evaluated and discussed in order to compare their performance as DSSC sensitizers. The theoretical results show that all dyes exhibit excellent optoelectronic properties, such as a lower E&amp;lt;sub&amp;gt;gap&amp;lt;/sub&amp;gt;(1.733 eV to 2.173 eV), a significant λ&amp;lt;sub&amp;gt;max&amp;lt;/sub&amp;gt;(631.48 nm to 754.40 nm), a sufficient value of V&amp;lt;sub&amp;gt;oc&amp;lt;/sub&amp;gt; (0.461 V to 0.880 V) and high LHE (0.853 eV to 0.968 eV). In particular M4 with 2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dithione as auxiliary acceptor has the potential to be used as a sensitizer for DSSCs, due to its red-shifted absorption spectrum (λ&amp;lt;sub&amp;gt;max&amp;lt;/sub&amp;gt;= 754.40 nm), and small energy gap (E&amp;lt;sub&amp;gt;gap&amp;lt;/sub&amp;gt;=1.733 eV). Indeed, this study may help chemists to synthesize efficient dyes for DSSC.

Nucleoside Phosphorylases make N7-xanthosine

Modern, highly evolved nucleoside-processing enzymes are known to exhibit perfect regioselectivity over the glycosylation of purine nucleobases at N9. We herein report an exception to this paradigm. Wild-type nucleoside phosphorylases also furnish N7-xanthosine, a “non-native” ribosylation regioisomer of xanthosine. This unusual nucleoside possesses several atypical physicochemical properties such as redshifted absorption spectra, a high equilibrium constant of phosphorolysis and low acidity. Ultimately, the biosynthesis of this previously unknown natural product illustrates how even highly evolved, essential enzymes from primary metabolism are imperfect catalysts.