Maximum Absorption Peak Research Articles

Effects of guar gum/chitosan edible films functionalized with citronellal/HPβCD inclusion complex on Harbin red sausage preservation

Harbin red sausage is a traditional local pork meat product in China, but it is susceptible to microbial contamination and lipid oxidation, leading to quality deterioration. Herein, guar gum (GG)/chitosan (CS) edible films functionalized with citronellal/hydroxypropyl-β-cyclodextrin inclusion complex (CIT/HPβCD-IC) were fabricated for Harbin red sausage preservation. Results demonstrated CIT/HPβCD-IC was successfully prepared and observed by SEM due to the bathochromic shift of maximum absorption peak of CIT, and the formation of new bonds was confirmed by FTIR analysis, suggesting the embedding of CIT into HPβCD cavity. The changes of functional groups stretching vibrations suggested successful loading of CIT/HPβCD-IC into the GG/CS edible films. Furthermore, the incorporation of CIT/HPβCD-IC enhanced the microstructural, mechanical and barrier properties, and improved the antibacterial activities, biodegradability and thermal stability of the GG/CS edible films. Particularly, the GG/CS edible films incorporated with 1 % CIT/HPβCD-IC (GG/CS-IC 1 %) enhanced the storage stability of Harbin red sausage at 4 °C by decreasing the weight loss rate, maintaining the pH, color, and textural stabilities, retarding the microbial growth and lipid oxidation of the sausage samples. Findings here suggested that GG/CS-IC 1 % edible films showed great potential as novel multi-functional edible packaging materials for Harbin red sausage preservation.

Extraction and characteristic properties analyses of sodium alginate derived from the Sargassum oligocystum brown seaweed alga of the Bay of Bengal

Sodium alginate extracted from Sargassum oligocystum brown seaweed alga is an important blue economy development process of the Bay of Bengal. In the present study, sodium alginate was extracted from the brown seaweed alga collected from the Cox’s Bazar coastal area of the Bay of Bengal. The extracted product was characterized with the Ultraviolet-visible (UV–visible) spectrophotometer, Fluorescence spectrophotometer, Fourier transform-infrared radiation (FT-IR) spectrophotometer, X-ray diffractometer (XRD), and Scanning electron microscope (SEM). The product yield was optimized with different pH levels and the maximum yield was obtained at 32.5 % at pH 10.96. The moisture, and ash content of the extracted product was measured and found at 13.25 % and 4.35 %, respectively. The viscosity of the extracted product was obtained at 60.1 mPs. The UV–visible spectrophotometry showed different absorbance peaks found at 234 nm, 240 nm, 250 nm, and 264 nm which assigned the extracted product of sodium alginate, and the maximum absorption peak lies at 276.7 nm which assigned flavonoids, and their derivatives of alginates. The fluorescence spectrophotometry demonstrated a strong emission peak at 460 nm with higher intensity (200), indicating the presence of sodium alginate. The FTIR showed the characteristic peaks that demonstrated different functional groups of sodium alginate. The XRD pattern demonstrated 0.24 crystalline indexes indicating the semi-crystalline product in nature. SEM showed clear fibrils of sodium alginate morphology indicating the absence of impurity materials.

Calix-like molecules with outstanding optical properties designed based on the Aza-BODIPY molecule: a DFT study

ABSTRACT Using aza-BODIPY chromophores 3–9 of aza-BODIPY units calix-like oligomers have been designed and studied structurally and thermodynamically. By performing optimisation calculations, it was found that firstly, all the structures are without imaginary frequency; secondly, they have high cohesive energy, which is proof of the stability of the structures. The highest amount of stability of the structures related to oligomer calix[9]-aza-BODIPY was determined by the cohesive energy about three times more than calix[8]-aza-BODIPY. To achieve the oligomers with higher colour intensity and improved optical and electrical properties, the H and F atoms from the upper edge of the calix structures were removed. It enlarges the resonance of the system and decreases the Eg of the systems. By removing the H and F atoms from the Calix molecules, the maximum absorption peaks were transferred to the visible area, and the intensity of light-colour properties in the structures was greatly increased. So, by increasing the size of the calixes, the optical properties are enhanced. Since it causes the most absorption for calixes 6, 7, 8 and 9 and the calix[8] -aza-BODIPY oligomer is detected as the most coloured molecule.

The synthesis, structures and characterizations of (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2 crystals

Two new organic-inorganic hybrid crystals (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2 were synthesized by solution method, and their basic physical properties, including structures, thermal stability analysis, UV–Vis diffuse reflectance absorption spectra and photoluminescent characteristic were characterized. The two crystals both crystallize in same monoclinic crystal system, but different P21/c and C2/c space group for (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2, respectively. Their infrared, Raman and mass spectrometry were measured, with related characteristic peaks were identified. The Raman peaks at 249 and 88 cm−1 are ascribed to Cd-Cl stretching vibration and Cl-Cd-Cl deformation vibration, respectively. The mass spectra analysis confirm the existence of C5H12NO+ cation, [CdCl]+ and Na-(C5H12NO)2BiCl6·H4O2. A phase transition peak that respectively located at 378 and 403 K for (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2 was detected by the synchronous thermal analysis, which is related with the loss of crystalline water in their structures. In addition, the maximum absorption peak at 230 and 240 nm, with corresponding band gap of 3.35 and 3.15 eV were fitted for (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2, respectively. Furthermore, (C5H12NO)4Cd3Cl10·2H2O features a bluish white emission with the peak centering at 496 nm when it was excited at 380 nm by a Xenon lamp. This work extends the catalog of organic-inorganic hybrid metal halides and presents the potential application of (C5H12NO)4Cd3Cl10·2H2O in optical field.

Optimizing energy absorption and peak force in metal/glass fiber sandwich panels with trapezoidal cores

Sandwich panels with trapezoidal metal/glass fiber cores are increasingly popular due to their lightweight and energy-absorption properties. This study employs response surface methodology (RSM) and Box-Behnken design to investigate the effects of core angle, fiber orientation, and MCM-48 nanoparticles on the panels’ energy absorption and peak force, developing regression models with high R2 values of 0.9027 and 0.9228, respectively. Experimental tests were conducted to validate these models, showing minimal deviation from predicted values. Results indicate that increasing the fiber orientation angle from 30° to 90° enhances energy absorption and peak force by 72.18 and 46.9%, respectively, and adding MCM-48 nanoparticles up to 0.25% weight improves energy absorption by 60.8%. A core angle of 52° balances energy absorption and peak force, while integrating a metal wire mesh within the panels significantly enhances energy absorption and reduces core brittleness. The optimal parameters for maximum energy absorption and minimum peak force include a core angle of 58°, fiber orientation of 73.5°, and no nanoparticles. These findings provide valuable insights into the design and optimization of sandwich panels for various applications.

Biosynthesis of selenium nanoparticles as a potential therapeutic agent in breast cancer: G2/M arrest and apoptosis induction

The drawbacks and adverse reactions of conventional breast cancer (BC) medications have prompted researchers to seek novel therapeutic approaches. This study aimed to study the impact of biosynthesized selenium nanoparticles by yeast on breast cancer (MCF-7) cells and to find potential underlying mechanisms. Therefore, marine yeast isolates were screened for their ability to biosynthesis selenium nanoparticles (SeNPs). The most potent isolate was identified as Candida pseudojiufengensis based on 18 S rRNA gene sequencing. Incubation of cell-free extract with 0.8 mM of SeO2 for 48 h at 40°C in pH of 7.0 were optimal conditions for the biosynthesis of SeNPs. The biosynthesized SeNPs were characterized by UV–Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and dynamic light scattering (DLS) measurements including average particle size distribution and average zeta potential. The results showed that the biosynthesized SeNPs displayed a maximum absorbance peak in the UV-Vis spectrum at 560 nm due to surface plasmon resonance. TEM image elevated spherical shape particles with an average size of 12 nm. SRB assay, flow cytometry, and other biochemical methods were employed to assess SeNPs anti-proliferative effects on MCF-7 cells. SeNPs showed superior anticancer efficacy against MCF-7 cells compared to colon (HCT-116) and liver (HepG2) cancer cells, as evidenced by lower IC50 values (19.59 µg/ml) against 36.36 µg/ml and 27.81 ±1.4 µg/ml, respectively. However, SeNPs demonstrated no cytotoxic effects against HSF cells. Moreover, treatment with SeNPs induces G2/M arrest along with triggering apoptosis in MCF-7 cells. Furthermore, MCF-7 cells treated with SeNPs showed increased oxidative stress, as indicated by observable rises in LPO and 8-OHDG, accompanied by considerable exhaustion in antioxidant enzyme activity. These findings demonstrated that Se nanoparticles synthesized from yeast have therapeutic promise in BC treatment.

Mitochondria-Targeted NIR Ratiometric and Colorimetric Fluorescent Probe for Biothiols Based on a Thiol-Chromene Click Reaction.

In this work, a mitochondria-targeted NIR ratiometric and colorimetric fluorescent probe 1 was tactfully designed and synthesized by a novel design strategy of modifying chromene to pyridine for the first time. 1 exhibited a maximum absorption peak at 508 nm and a maximum fluorescence emission peak at 650 nm. Under the stimulus of biothiols (cysteine (Cys), homocysteine (Hcy), and glutathione (GSH)), the maximum absorption and fluorescence emission peaks of 1 blue-shifted to 448 and 541 nm, respectively, along with color changes from red to yellow under visible light and from red to green under a 365 nm ultraviolet (UV) lamp, which can be ascribed to the click reaction of biothiols with the α,β-unsaturated ketone of the chromene moiety with pyran ring-opening, phenol formation, and 1,6-elimination of the p-hydroxybenzyl moiety. 1 detected biothiols (Cys, GSH, and Hcy) with high sensitivity (LODs of 29, 23, and 16 nM for Cys, GSH, and Hcy, respectively), excellent selectivity, and fast response. Moreover, 1 can target mitochondria and image the fluctuation of intracellular biothiols by dual-emission channels.

Investigation of the Structure and Optical Properties of Polymethine-Based NIR-II Fluorophores Using Many-Body Perturbation Theory: GW-BSE Approaches.

Fluorescence imaging is a widely used technique for detecting pathophysiological microenvironments and guiding fluorescence-guided therapy owing to its noninvasiveness, high spatiotemporal resolution, ease of operation, and real-time monitoring capabilities. In particular, NIR-II materials are promising for fluorescence imaging applications because they exhibit reduced light scattering and absorption by biological tissues, enabling deeper imaging with improved spatial resolution and contrast compared to visible or first near-infrared imaging. NIR-II materials refer to those that emit in the second near-infrared region of the electromagnetic spectrum, spanning wavelengths from approximately 1000 to 1700 nm. The emission peaks of organic fluorophores within the NIR-II window are of particular interest due to their minimal biotoxicity, in vivo biocompatibility, and biodegradability. In this study, we investigated a new series of NIR-II fluorescent polymethine-based dyes and their NIR-II absorption properties using density functional theory and the GW-BSE approximation. Our calculated maximum absorption peak under the GW-BSE approximation showed good agreement with experimental results, demonstrating the potential of these dyes for NIR-II fluorescence imaging applications.

Efficient synthesis of conjugated 2-(9H-fluoren-7-yl)-9H-fluorene via Br elimination in 2-bromofluorene using electron beam-irradiation

This study demonstrates the synthesis of conjugated 2-(9H-fluoren-7-yl)-9H-fluorene using electron beam irradiation within 3 min in place of the conventional catalytic cross-coupling reactions. 2-bromofluorene was irradiated at various doses (10, 30, 50, 70, 90, and 100 kGy), resulting in the elimination of Br from the 2-position and the formation of C–C bonds between the Br-eliminated fluorenes. The yield of 2-(9H-fluoren-7-yl)-9H-fluorene increased with higher absorbed doses, reaching 65% at 100 kGy. UV–Vis absorption of synthesized 2-(9H-fluoren-7-yl)-9H-fluorene showed an onset at 357 nm and a maximum absorption peak at 325 nm, and blue emission ranging from 340 to 450 nm in photoluminescence (PL). The results of UV–Vis absorption and PL indicated expanded conjugation of 2-(9H-fluoren-7-yl)-9H-fluorene due to the formation of C–C bonds between 2-bromofluorene through the electron beam-induced coupling reaction. Electron beam irradiation offers the potential to significantly reduce the reaction times for synthesis of conjugated organic compounds.

Electronic, optical, and thermoelectric behaviour of KCuX (X = S, Se, Te) monolayers.

In the past few decades, two-dimensional (2-D) materials gained huge deliberation due to their outstanding electronic and heat transport properties. These materials have effective applications in many areas such as photodetectors, battery electrodes, thermoelectrics, etc. In this work, we have calculated structural, electronic, optical, and thermoelectric properties of KCuX (X = S, Se, Te) monolayers (MLs) with the help of first-principles-based calculations and semi-classical Boltz- mann transport equation (BTE). The phonon dispersion calculations demonstrate the dynamical stability of the KCuX (X = S, Se, Te) MLs. Our results show that the monolayers of KCuX (X = S, Se, Te) are semiconductors with band gaps of 0.193 eV, 0.26 eV, and 1.001 eV respectively, and therefore they are suitable for photovoltaic applications. The optical analysis illustrates that the maximum absorption peaks of the KCuX (X = S, Se, Te) MLs are located in visible and ultraviolet (UV) regions, which may serve as a promising candidate for designing advanced optoelectronic devices. Furthermore, thermoelectric properties of the KCuS and KCuSe MLs, including See- beck coefficient, electrical conductivity, electronic thermal conductivity, power factor, and figure of merit, are calculated at different temperatures 300 K, 600 K, and 800 K. Additionally, we also focus on the analysis of Gru ̈neisen parameter and various scattering rates to further explain their ultra-low thermal conductivity. Our results show that KCuS and KCuSe possess ultra-low lattice thermal conductivity value of 0.15 Wm-1K-1 and 0.06 Wm-1K-1 respectively, which is lower than those of recently reported KAgSe (0.26 Wm-1K-1 at 300 K) and TlCuSe (0.44 Wm-1K-1 at 300 K), indicating towards the large value of ZT. These materials are found to possess desirable thermoelectric and optical properties, making them suitable candidates for efficient thermoelectric and optoelectronic device applications.

Photovoltaic Molecule-Based Phototheranostics With A-D-A Structure for Near-Infrared Fluorescence Imaging-Guided Synergetic Photodynamic and Photothermal Therapy of Tumors.

Phototheranostics with near-infrared fluorescence and reactive oxygen species generation ability and high photothermal conversion efficiency (PCE) plays a significant role in fluorescence imaging-guided synergetic photodynamic and photothermal therapy of tumors. Here, a star molecule in organic photovoltaic materials, NCBDT-4C with an A-D-A conjugated structure, was assembled with DSPE-PEG-NH2 to prepare water dispersive nanoparticles (NPs). The prepared NCBDT-4Cl NPs exhibited a maximum NIR absorption peak at 764 nm and a maximum fluorescence peak at 798 nm. These NPs could generate superoxide anion, singlet oxygen (1O2), and heat under 808 nm laser irradiation. The 1O2 generation quantum yield and PCE of the NPs were 37.5% and 53.6%, respectively. The combination of photodynamic and photothermal therapy of cancer was demonstrated invitro and invivo. This work presents the advanced application of organic photovoltaic materials in cancer phototherapy.

Green synthesis of ZnO/Fe3O4 nanoparticles with nigella sativa extract: Efficient degradation of methylene blue and antimicrobial properties

Zinc oxide (ZnO), iron oxide (Fe3O4) NPs, and ZnO/Fe3O4 nanocomposites (NCs) were synthesized using Nigella sativa (NS) seed extracts. These nanomaterials (NMs) were characterized by multiple analytical techniques like UV-visible spectrophotometers, FTIR spectroscopy, SEM, and XRD spectroscopy. The UV-visible spectrum showed 364 nm, 330 nm, and 331nm for ZnO NPs, Fe3O4 NPs, and ZnO/Fe3O4 NCs, respectively. Moreover, it was confirmed when the samples were run through FTIR techniques, and it was observed that the availability of bioactive functional groups was involved in the decline of bulk compounds to NPs. XRD showed their average nanoparticle size based on applying the formula of full width at half maximum (FWHM) for ZnO NPs, Fe3O4 NPs, and ZnO/Fe3O4 NCs at 29.52 nm, 22.08 nm, and 12.82 nm, respectively. In this study, the reduction of Methylene Blue (MB) dye was done by NPs and NCs, and their catalytic activities were investigated by a UV-visible spectrophotometer. MB dye showed the maximum absorption peak at 664 nm, and the reaction of MB was reduced using synthesized products with an accompanying color change reaction from blue to colorless within 60 min at 84%, 86%, and 99.5% degradation for ZnO NPs, Fe3O4 NPs, and ZnO/Fe3O4 NCs with rate constants of 0.00035, 0.00065, and 0.0015 Lmol-1S-1. The 2nd order rate constant was observed in this study. The agar disc diffusion method was used to investigate the potential antibacterial activity of synthesized NPs and NCs. This study is best suited for Gram-positive bacteria. NS seed extract-based synthesis of NCs could be an excellent catalyst and biological application for environmental pollution.

Saponin-mediated and microwave-assisted biosynthesis of silver nanoparticles: preparations and anticancer assessment

Silver nanoparticles have been extensively studied and used for biological and biomedical applications due to its antimicrobial properties. In this study, we have developed silver nanoparticles with saponin (S-AgNPs) using microwave-mediated methodology and physiochemically characterised and evaluated its anticancer potential. According to UV–visible spectroscopy, S-AgNPs exhibited a maximum absorption peak at a wavelength of 420 nm. DLS analysis revealed that S-AgNPs have an average diameter of around 133.8 ± 10 nm. HR-TEM analysis confirms the spherical morphology of S-AgNPs. Further, the anticancer effect of S-AgNPs was validated using A459 lung cancer cells by in vitro cell interaction tests such as the MTT assay, staining assay, and flow cytometry assay. The IC50 value of S-AgNPs against A549 cells was 30 μg ml−1, and Calcein-EtBr and Annexin V/PI staining results confirm the presence of apoptotic cells after treatment S-AgNPs. Hence, biosynthesized S-AgNPs can play a vital role in developing anticancer drugs for cancer treatment.

Characterization of structural and spectroscopic properties of ZnO/Fe₂O₃ nanocomposites

Powder nanoparticles of ZnO/Fe2O3 composites with varying concentrations of precessour have been synthesized with the help of the co-precipitation method followed by annealing and milling the composite at 700 °C. Then, the obtained powder composites were characterized by X-ray diffraction, Fourier Transformation Infrared spectroscopy, Field Emission Scanning electron microscopy with EDX, Raman spectroscopy, UV–visible absorption spectroscopy, and Photolumnisences. The powder X-ray diffraction results show the formation of the well-crystalline phase of ZnO/Fe2O3. For the further study of the structural analysis, we have done the Rietveld refinement of the XRD data. Williams-hall plot was used to calculate the lattice strain of the composites. Crystalline size, dislocation density, and Rietveld parameters were also calculated using the XRD and Rietveld refinement methods. FESEM study revealed that with an increase in the concentration of Fe2O3, the shape of the composite changes from spherical to nanosheets via nanorods. The absorption peaks and vibration band obtained at zftir and RAMAN spectra show the formation of the ZnO/Fe2O3. The UV–visible absorption spectroscopy shows the maximum absorption peak in the 200–400 nm range. The successfully synthesized nanocomposites ZnO/Fe2O3 indicate that it can be a potential candidate for organic pollutant degradation.

Synthesis and Characterization of Silver Nanoparticles Stabilized with Biosurfactant and Application as an Antimicrobial Agent.

Surfactants can be used as nanoparticle stabilizing agents. However, since synthetic surfactants are not economically viable and environmentally friendly, biosurfactants are emerging as a green alternative for the synthesis and stabilization of nanoparticles. Nanoparticles have been applied in several areas of industry, such as the production of biomedical and therapeutic components, packaging coating, solar energy generation and transmission and distribution of electrical energy, among others. The aim of this study was to synthesize, in a simple and green way, silver nanoparticles (AgNPs) using the biosurfactant produced by Candida lipolytica UCP 0899 as a stabilizer. AgNPs were examined and morphologically characterized using the techniques of ultraviolet-visible spectroscopy (UV-visible), scanning electron microscopy (SEM), zeta potential and energy dispersive X-ray spectroscopy (EDS). Newly formed silver nanoparticles showed a maximum UV-visible absorption peak at 400 nm, while a shift to 410 nm was observed in those stored for 120 days. SEM micrograph confirmed the formation of nanoparticles with an average size of 20 nm and with a predominant spherical structure, while a zeta potential of -60 mV suggested that the use of the biosurfactant promoted their stability. Stabilized nanoparticles were tested for their antimicrobial activity against bacterial isolates of Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Enterobacter sp., as well as fungal isolates of Candida albicans and Aspergillus niger. At a concentration of 16.50 µg/mL, AgNPs inhibited the growth of all target microorganisms according to the following decreasing order: E. coli (95%), S. aureus, C. albicans (90%), A. niger (85%), Enterobacter sp. (75%) and P. aeruginosa (71%). These results suggest the potential use of the biosurfactant as a stabilizer of silver nanoparticles as an antimicrobial agent in different industrial sectors. Furthermore, the in vivo toxicity potential of biosurfactants was evaluated using the Tenebrio molitor model. The larvae were treated with concentrations in the range of 2.5, 5.0 and 10 g/L, and no mortality was observed within the 24 to 72 h period, demonstrating non-toxicity within the tested concentration range. These findings support the safety, efficacy and non-toxicity of biosurfactant-stabilized nanoparticles.

Production and Antibacterial Activity of Atypical Siderophore from Pseudomonas sp. QCS59 Recovered from Harpachene schimperi.

Among sixty-eight pseudomonads, isolate QCS59 from the rhizosphere of H. schimperi was selected based on its siderophore level. Production was optimal in Kings B supplemented with 2% peptone and 0.5% fructose at pH 6.5 and 25 °C for 72 h. Additionally, the threshold potential of iron was found at a concentration of 10 µM. After purification, the acidified siderophore presented a maximum absorption peak of 360 nm, while the neutral form presented a maximum of 414 nm, confirming its pyoverdine (PVD) nature. Furthermore, a major peak appeared at a retention time (RT) of 27.5 min during RP-HPLC, confirming its homogeneity. Interestingly, it demonstrated effective antibacterial activity, especially against Escherichia coli ATCC 8739, with a minimum inhibitory concentration (MIC) of 6.3 µg/mL and a minimum bactericidal concentration (MBC) of 12.5 µg/mL. At ½ the MIC value, it inhibited 82.1% of well-established biofilms of Salmonella enterica. There was an increase in malondialdehyde (MDA) and antioxidative enzymes, especially catalase (CAT) in the treated bacteria because of the peroxidation of membrane lipids and oxidative stress, respectively. SEM proved cellular lysis and surface malformation in most of the treated bacteria. This study concludes that QCS59 siderophore is a promising antibacterial candidate for treating wastewater bacteria and skin pathogens.

One pot synthesis and crystal of N-benzoyl(benzo)thiazol-2-amine borodifluoride complexes (NBO) with aggregation induced luminescence properties

In this paper, N-benzoyl(benzo)thiazol-2-amine borodifluoride complexes (NBOs) were synthesized directly from benzoyl chloride and (benzo)thiazol-2-amine by one-pot method. The molecular structures of the target compounds were characterized by nuclear magnetic resonance (NMR), high resolution mass spectrometry and single crystal X-ray diffraction. The optical properties of the compounds were measured by UV–Vis absorption and fluorescence spectra. In CH2Cl2, this compounds exhibit large Stokes shifts, the maximum absorption peaks of NBO-1, NBO-2 and NBO-3 are 327 nm, 342 nm and 362 nm, and the maximum emission peaks are 400 nm, 442 nm and 498 nm, respectively. It can also be found that the absorption and emission spectra are redshifted with the increase of the conjugated system. Further more, we found that NBO-2 and NBO-3 molecules with additional benzo structure have the properties of aggregation induced emission, while NBO-1 show weak fluorescence in both solution and aggregation state.

Biaxial strain-modulated power conversion efficiency, electronic structures, and optical properties of type-II MoS2/BC6N vdW heterostructure: A density functional theory study

The power conversion efficiency (PCE), electronic structures, and optical properties of a novel MoS2/BC6N van der Waals heterostructure (vdWH) were systematically investigated under different biaxial strains ranging from –8–8 % by first-principles density functional theory calculations. The semiconductive MoS2/BC6N vdWH exhibited indirect bandgap (1.02 eV) with type-II band alignment. The bandgap of the MoS2/BC6N vdWH decreased to 0.57 eV with increasing tensile strain, and increased to 1.57 eV with increasing compressive strain. When the strain exceeded –4 %, the band alignment of the vdWH transformed from type-II to type-I, exhibiting a direct bandgap. Strong optical absorption of the MoS2/BC6N vdWH was observed in the visible and ultraviolet regions. The maximum absorption peak produced a redshift with increasing tensile strain and a blueshift as increasing compressive strain. The PCE of the intrinsic MoS2/BC6N vdWH was 11.5 %, which gradually increased with increasing compressive strain but decreased with increasing tensile strain, that is, PCEs of 5.6 %, 8.0 %, 16.1 %, and 22.8 % for strain of 4 %, 2 %, –2 %, and –4 %, respectively. Therefore, the biaxial strain can effectively modulate the electronic structures, optical properties, and PCE of MoS2/BC6N vdWH. Moreover, their excellent optical properties and ultrahigh PCE indicate their significant potential for use in photovoltaic devices.

Highly thermo- and photo-stable acceptor-acceptor′-acceptor type perylenediimide dimeric acceptors: Role of monofluorinating the central benzo[c][1,2,5]thiadiazole linking core

Acceptor-Acceptor′-Acceptor (A-A′-A) type perylene diimide (PDI)-based dimeric non-fullerene electron acceptors (NFEAs) have drawn the special attention but have not been sufficiently exploited. With that in mind, two A-A′-A type NFEAs, DTBT-(PDI-HD)2 and DTFBT-(PDI-HD)2, in which 4,7-di(thien-2-yl)benzo[c][1,2,5]thiadiazole (DTBT) and its monofluorinated 4,7-di(thien-2-yl)-5-fluorobenzo[c][1,2,5]thiadiazole (DTFBT) as central linkers, both N,N′-(2-hexyldecyl)-PDI (PDI-HD) units as flanked biwings, were successfully synthesized to probe into the influence of different electron-deficient linkers on thermo- and photo-stability, absorption, energy level, molecular configuration, exciton dissociation, charge mobility and solar cell performance. Both A-A′-A type acceptors with excellent thermal- and photo-stability possessed the complementary absorption ranging from 300 nm to 780 nm and matched ELUMO of −3.84 eV to −3.91 eV when pairing with PTB7-Th. Moreover, increased molecular dipole moment, slightly blue-shifted the maximum absorption peak, decreased the absorption coefficient and deepened the ELUMO were found after monofluorinating the benzothiadiazole. Conversely, the augmented aggregation both in solution and film effectively tuned the miscibility and morphology of active layer, contributing to the improvements of the exciton dissociation, charge mobility and photocurrent. Benefiting from this, monofluorinating the electron-deficient benzothiadiazole linker made the JSC increase from 3.72 to 7.19 mA cm−2, the FF enhance from 34.99 % to 38.18 % in DTFBT-(PDI-HD)2-based device when blending with PTB7-Th, contributing to 1.09 times increased PCE from 1.03 % to 2.15 % even in the adverse condition of 0.01 V dropped VOC. These results suggest that monofluorinating the electron-deficient benzothiadiazole linker is an effective approach for boosting the device efficiency via tuning the molecular aggregation and affecting the related morphology and charge mobility during the A-A′-A type PDI-based NFEAs.

Solvatochromism mechanism of perylene diimide radicals stabilized by low barrier hydrogen bond and detection of formaldehyde in real food samples

Formaldehyde (FA) is widely used for food preservation and whitening because of its preservative and bleaching effects. Excessive FA seriously endangers human health, so monitoring FA-treated food is of great significance for food safety. In this paper, perylene diimide radicals with the chirality (BTFPDI) and water-solubility (TFPDI-bPEI) were designed respectively based on our previous studies. Property of solvatochromism induced by these perylene diimide radicals aggregation was demonstrated by the concentration and temperature dependent absorption spectrum and the circular dichroism spectrum. Further the colorimetric monitoring of trace FA in gaseous and liquid was realized by the condensation reaction of FA with amine to induce TFPDI-bPEI aggregation. After the addition of FA, TFPDI-bPEI molecule aggregated in aqueous solution due to the specific reaction of a large number of –NH2 groups with FA, resulting in a blue-shift of the maximum absorption peak from 780 nm to 561 nm, and the detection limit as low as 0.86 μM to FA and the response time of only 20 s. This method could further detect FA in food with good recoveries and detect FA in contaminated food samples.