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A reaction-based turn-on fluorescent sensor for the detection of Cu (II) with excellent sensitivity and selectivity: Synthesis, DFT calculations, kinetics and application in real water samples
摘要： A reaction-based turn-on fluorescent chemosensor RhB-Cu, starting from rhodamine B (RhB), for Cu2+ was easily synthesized in two steps. The sensor could selectively detect Cu2+ with a 100-fold fluorescence enhancement among the common metal ions, exhibiting an extremely low detection limit of 4.7 nM. To the best of our knowledge, this was the best record for the detection of Cu2+ with organic fluorescent sensors. There was a 1:1 binding stoichiometry between RhB-Cu and Cu2+ with an association constant of 6.42 × 104 M-1. Noteworthy, it could distinguish Cu2+ from Cu+, which was hard to realize in the previous studies. In addition, the detection mechanism was proposed based on mass spectrometric analysis and density functional theory (DFT) calculations. Kinetic studies were conducted to obtain the activation energy, enthalpy and entropy, so as to elucidate the solvent effect. Interestingly, the kinetic compensation effect (KCE) was uncovered in this work. Finally, RhB-Cu was proved to have the capability to work in real water samples. It would highly contribute to the even better design of fluorescent sensor for Cu2+ in future.
关键词： fluorescent sensor,solvent effect,kinetic compensation effect (KCE),copper,density functional theory (DFT),PET mechanism
更新于2025-10-22 19:38:57
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Structure, Reactivity, Nonlinear Optical Properties and Vibrational Study of 5-Thioxo-1,4-thiazaolidin-3-one and 5-thioxo-1,4,2-thiazasilolidin-3-one (Silicon vs. Carbon). A DFT Study
摘要： The structures and nonlinear optical properties (NLO) of 5-thioxo-1,4-thiazaolidin-3-one(Rhodanine) and 5-thioxo-1,4,2-thiazasilolidin-3-one (silarhodanine) tautomers were studied in gas phase and in solutions using the B3LYP density functional theory and composite CBS-QB3 method. The global minimum at the B3LYP/6-31++G(d,p) and CBS-QB3 levels of theory is tautomer 5 in the gas phase and in solvents for rhodanine, and simiarly, tautomer 13 is the global minimum for silarhodanine. The interconversion among the tautomers is proceeded by an intramolecular proton transfer reaction. An identical solvent effects can be noted for rhodanine and silarhodanine tautomers. The activation barrier towards ring-opening processes (1→2, 9→10) decreases with the increasing dielectric constant of the solvent; on the other hand, the barrier of the ring-closure processes (2→3, 10→11) increases with the increasing dielectric constant. The tautomers are predicted to show significant NLO properties. Also, a number of correlations between the dipole moment and electron densities in bond critical points of the S3-C4 bond and interaction energy as well as vibrational frequencies at the transition states (TS2–3,TS10–11) were examined under different solvents. Finally, the investigation of the heavy atom substitution effects on the properties of silarhodanine is proven to be very weak under these conditions.
关键词： Vibrational assignments,Silarhodanine,Reactivity,Rhodanine,NLO,Ring-opening,Solvent effects
更新于2025-09-23 15:23:52
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Application of polar solvent effects in absorption spectra for determination of lowest electron-excited states of phthalide
摘要： The optical absorption spectra of phthalide in polar (methanol) and nonpolar (n-hexane) solvents are recorded. The electronic phthalide spectrum was calculated by TDDFT B3LYP/6-311+G(d, p) using the polarisable continuum model. Based on an analysis of calculation data and the displacement of absorption bands in a polar solvent, it was established that the absorption bands of phthalide at energies of 3.51 and 3.96 eV correspond to singlet-triplet transitions to the T1 and T2 states, respectively.
关键词： Triplet excited states,Electronic absorption spectra,PCM TDDFT,Solvent effect,Phthalide
更新于2025-09-23 15:23:52
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Solvent-free Method to Encapsulate Polyoxometalate into Metal-Organic Frameworks as Efficient and Recyclable Photocatalyst for Harmful Sulfamethazine Degrading in Water
摘要： Through a less-investigated in-situ hot-pressing synthesis method, the phosphotungstic acid H3PW12O40 (denoted as PW12) was rapidly incorporated into a metal-organic framework MFM-300(In) in a short time, affording novel PW12@MFM-300(In) composites. This solvent-free preparation process is not only environment-friendly but also energy/time-saving. The inclusion of PW12 in MFM-300(In) was demonstrated by different physical and chemical characterizations. It was interesting to find that PW12@MFM-300(In) as new heterocatalysts display synergistic activity for the visible-light-driven catalytic degradation of pharmaceutically active compound sulfamethazine (SMT). 4-PW12@MFM-300(In) with excellent robustness possesses the high removal efficiency of about 98% toward SMT within 2 h at room temperature, and can also be recycled multiple times for this catalytic process.
关键词： polyoxometalate,metal-organic framework,solvent-free,sulfamethazine,photocatalytic materials
更新于2025-09-23 15:23:52
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Effect of acceptor moieties on static and dynamic first hyperpolarizability of azobenzene chromophores
摘要： The effect of acceptor on static and dynamic first hyperpolarizability, β, of trans- and cis-isomers of azochromophores AAB-DCV and AAB-TCV is studied. Calculations were performed by MP2 and DFT with three density functionals: M06-2X, CAM-B3LYP and ωB97X-D in gas phase and chloroform. Dynamic first hyperpolarizabilities were calculated by TD-DFT at 1.165 and 0.65 eV. The first hyperpolarizability values for trans-isomers are approximately three times greater than those for cis-isomer; solvent effect is essential comprising 2.7 and 3.2 times growth for static values for AAB-DCV and AAB-TCV, respectively, the corresponding dynamic estimations for βtot(2ω) being slightly smaller (2.2 and 2.6 times).
关键词： Dynamic characteristics,MP2,Azochromophore,Solvent effect,Acceptor effect,First hyperpolarizability,Density functional theory,TD-DFT
更新于2025-09-23 15:23:52
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Chain End-Functionalized Polymer Brushes with Switchable Fluorescence Response
摘要： Herein is described the switchable fluorescence response of poly(methyl methacrylate) (PMMA) brushes. Chain end fluorescein labeled PMMA brushes are prepared by combining surface-initiated atom transfer radical polymerization (SI-ATRP) with a copper-catalyzed alkyne-azide cycloaddition (CuAAC) click reaction. Successful attachment of fluorescein is confirmed by measuring fluorescence of the as-prepared films. Utilizing co-solvency of PMMA in isopropanol-water mixtures, responsive behavior of the end-functionalized brushes is demonstrated by measuring the changes in fluorescence intensity between the swollen and collapsed states.
关键词： fluorescent polymers,polymer brushes,co-solvency,solvent responsiveness
更新于2025-09-23 15:23:52
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FDISCO: Advanced solvent-based clearing method for imaging whole organs
摘要： Various optical clearing methods have emerged as powerful tools for deep biological imaging. Organic solvent–based clearing methods, such as three-dimensional imaging of solvent-cleared organs (3DISCO), present the advantages of high clearing efficiency and size reduction for panoptic imaging of large samples such as whole organs and even whole bodies. However, 3DISCO results in a rapid quenching of endogenous fluorescence, which has impeded its application. Here, we propose an advanced method named FDISCO to overcome this limitation. FDISCO can effectively preserve the fluorescence of various fluorescent probes and can achieve a long storage time of months while retaining potent clearing capability. We used FDISCO for high-resolution imaging and reconstruction of neuronal and vascular networks. Moreover, FDISCO is compatible with labeling by multiple viruses and enables fine visualization of neurons with weak fluorescence labeling in the whole brain. FDISCO represents an effective alternative to the three-dimensional mapping of whole organs and can be extensively used in biomedical studies.
关键词： fluorescence preservation,FDISCO,solvent-based methods,optical clearing,whole-organ imaging
更新于2025-09-23 15:22:29
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Characterization and removal of antibiotic residues by NFC-doped photocatalytic oxidation from domestic and industrial secondary treated wastewaters in Meric-Ergene Basin and reuse assessment for irrigation
摘要： Antibiotics are important contaminants that have become an increasingly big problem due to the discharge of the receiving environment. The presence of these organic based pollutants in influent wastewater can inhibit the biological processes and resist to degradation in wastewater treatment plants. Moreover, the consumption of agricultural products, irrigated with water containing antibiotic residues, leads to major harmful effects to the human body through the food chain. In this study; firstly, a conventional characterization was made in terms of COD, TOC, SS, color and of antibiotic residue characterization of untreated raw (influent) and biologically treated (effluent) water from domestic and industrial wastewater treatment plants located in the Meri?-Ergene Basin. After that, photocatalytic activity test was run under visible light for selected antibiotics (Erythromycin, Ciprofloxacin, Sulphametoxasol) which were detected by HPLC MS/MS in excess amount. Finally, for the photocatalytic oxidation, a new generation NFC (Nitrogen-Floride-Carbon)-doped titanium dioxide photocatalyst, which has never been studied in the literature before, was prepared according to the sol-gel method without using thermal processing. Photocatalysts were characterized by UV–vis DRS reflectance and Laser Raman Spectra measurements. All other analyzes were made according to the standard methods. Considering the conventional characterization results; investigated domestic wastewaters exhibited moderate characteristics while industrial wastewater samples had strong characteristics in terms of COD, TOC and SS pollution in accordance with the literature. By the way, contrary to expectations, antibiotic residue results have proved that the effluent wastewater contains more antibiotics than the influent. This can be explained by the fact that, some antibiotics in domestic wastewaters are probably already trapped in feces and cannot be purified by conventional systems since they are released after biological treatment, as mentioned similar studies in the literature. Moreover, by means of 7 h NFC-doped photocatalytic oxidation under visible light, beside approximately % 62 to %79 COD and 62%–86% TOC removal, %99 to %100 removal of antibiotic residue was provided. According to these results, domestic and industrial secondary treated wastewaters in Meric-Ergene Basin can be advance treated, succesfully, with NFC-doped photocatalyst to remove antibiotic residues besides conventional pollutants. This result show that Meri?-Ergene discharge criteria determined by Forest and Water Ministry of Turkey can be provided with this new type photocatalytic process and healthy reuse of this river for irrigation will be possible.
关键词： Advanced oxidation processes,Domestic/industrial wastewater,Solvent-casting method,UV,Antibiotic,Photocatalyst,NFC-doped TiO2
更新于2025-09-23 15:22:29
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Fabrication of UV-curable solvent-free epoxy modified silicone resin coating with high transparency and low volume shrinkage
摘要： A type of solvent-free transparent epoxy modified silicone resin coating with high transparency and low volume shrinkage was produced by UV curing method. The features of the UV curing process were studied. The performances of the silicone coating obtained such as transparency, thermal stability and the volume shrinkage were also investigated in detail, which expressed that the materials obtained were with good thermal stability, good adhesive ability and fairly low volume shrinkage.
关键词： UV curing,Transparent coating,Epoxy modified silicone resin,Solvent-Free
更新于2025-09-23 15:22:29
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Liquid Phase Studies of Nanomaterials
摘要： Liquid cell transmission electron microscopy (LCTEM) is a relatively new technique enabling researchers to study dynamic phenomena in materials sciences, life sciences and electrochemistry. LCTEM has proved to be a remarkable tool for observing colloidal nanoparticle syntheses at fairly high temporal and spatial resolutions offered by transmission electron microscopy (TEM). Though the idea of observing syntheses in their native media is not new, a practical approach has only been made possible through massive improvements in microfabrication technology to fabricate liquid cells.[1] The idea is to use thin window materials such as SiN membranes (50 nm or less) to encapsulate tens of cubic nanometers of liquid in a stable thin profile suitable forTEM imaging considering the vacuum environment of the microscope (Fig. 1).
关键词： Radiolysis,Nanoparticles,Electron beam irradiation,Solvent,Liquid cell TEM
更新于2025-09-23 15:21:21