查看更多>>摘要：A novel white light emitting silicate-based phosphor of Dy3+ activated KBaScSi3O9 (xDyKBS) was prepared by a conventional solid state method. Powder X-ray diffraction patterns represent the pure phase of synthesized materials that was formed with monoclinic structure. The metal-ligand bonding nature and electronic band structure have been examined optical absorption spectra. The luminescence emission curves of the silicate phosphors display an intense yellow emission peak at 579 nm and a blue emission peak at 491 nm. Among the emission bands, the band observed in the yellow region due to F-4(9/2)-> H-6(13/2) transition was found to be higher intensity. The radiative parameters like transition probabilities (A(R)), branching ratios (beta(R)) and stimulated emission cross-section (sigma(E)(P)) values were calculated using Judd-Ofelt parameters and refractive index values for the observed transitions in emission spectra. The life time measurements were made for F-4(9/2) -> H-6(13/2) transition of all the studied samples by keeping an excitation at 350 nm and emission at 579 nm and decay curves were fitted to bi-exponential fitting method. The CCT values obtained from the color coordinates suggested that present xDyKBS phosphors can emit warm and neutral white light depending upon the dopant concentration under near-UV excitation. Our results demonstrated that the optimum concentration 0.05DyKBS phosphor can be successfully utilized as a promising and potential candidate for various innovative photonic applications like warm white LEDs, solar cells, optical sensors and lasers. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new approach to determine the local anesthetic benoxinate spectrofluorimetrically was developed. It was found that benoxinate exhibits strong native fluorescence in ethanol at 371 nm after excitation at 297 nm. There was a linear response between the fluorescence intensity and the concentration of the studied drug over the range of 10.0-100.0 ng/ mL. The suggested spectrofluorimetric method was optimized and validated following the pharmacopoeial guidelines. The obtained results were fully discussed and statistically analyzed in relevance to a previous published spectroscopic method. The limit of quantification (LOQ) of the present method was 1.79 ng/mL. Inter-day and intra-day precision relative standard deviations were lower than 1.5%. Finally, the proposed methodology has been adopted for determination of benoxinate in aqueous humor with a mean percentage recovery 99.87 +/- 1.66 as well as in the pharmaceutical eye drops with a mean percentage recovery 100.37 +/- 1.32. The method is cost-effective and green as it depends in water and ethanol mainly. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Hypochlorite plays a significant role in physiological processes, particularly regulation of lysosomal functions, and is involved in various diseases. Thus, it is crucial to develop highly sensitive and selective molecule tools to detect HClO in lysosomes. Herein, a novel 2H-benzo[h]chromene-pyridine derivative (1) was synthesized through condensation reaction, which exhibited a notable deep-red emission at 640 nm in pure water. This deep-red emission was specifically quenched by adding ClO-. The response of probe 1 toward ClO- was rapid (within 10 s), sensitive (detection limit of 0.012 mu M), and effective over a wide range of pH (1.0-12.0). Due to the existence of morpholine as the lysosome-targeting unit, the probe was successfully utilized to monitor lysosomal ClO-. Moreover, the probe 1 was also applied to detecting ClO- in zebrafish. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Hydrazine, as a toxic substance, seriously endangers human health and the environment. Based on the excellent luminescent properties and low biological toxicity of pyrene derivatives, combing with chalcone derivatives easily attacked by nucleophilic group, a pyrene derivative PCA decorated by acryloyl terminal group as fluorescent probe for hydrazine was developed. The compound shows fluorescent peak red shift and intensity enhancement with increasing solvent polarity from hexane (459 nm) to methanol (561 nm). Based on strong fluorescence emission in methanol, methanol-HEPES mixed solution was used as the solvent in the spectral recognition experiments. The probe exhibits fluorescent change from yellow fluorescence (576 nm) to blue fluorescence (393 nm) with 800-fold ratiometric fluorescence enhancement (I-393nm/I-576nm) after the reaction with hydrazine. The probe can recognize hydrazine in fast response rate with kinetic constant calculated being 2.7 x 10(-3) s(-1) and 15 min as response time. The probe also can monitor hydrazine in real water samples and various soils. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new Schiff base 2-ethoxy-3-{[(6-{[(2-ethoxy-4-hydroxy-2H-chromen-3-yl)methylidene]amino}pyri dine-2-yl)imino]methyl}-2H-chromen-4-ol (CD) was synthesized as a result of the condensation of 2,6-diaminopyridine and 3-formyl chromone in 1:2 M ratio and used for cupric ions detection and characterized through FTIR, HRMS and H-1 NMR spectral techniques. The sensing capability of Schiff base for cupric ions as compared to other transition metal ions was examined by absorbance and emission studies. A considerable decrease in emission intensity appeared in Schiff base in the case of cupric ions while irrelevant changes were examined for the rest of the ions. The binding stoichiometry was obtained as 1:2 for CD: Cu2+ complex intended from the job's plot which was confirmed through HRMS spectral technique. DFT calculations were carried for the confirmation of structural relationships and absorption-emission data. The Regression coefficient, Limit of detection, and Association constant were obtained as 98.7%, 1.2 x 10(-6) M, and 3.26 x 10(4) M-1 respectively using Benesi-Hildebrand (B-H) equation. The sensing power of Schiff base CD to recognize cupric ions was unaltered by the addition of the rest of metal ions, which was authenticated through interference studies. Schiff base CD and its complex with cupric ions were found stable over an extensive time period as revealed by time-reliant studies. The data collected by pH studies revealed that the preferred pH range for detecting cupric ions by Schiff base CD was 6 to 11. The Schiff base was finally utilized for sensing cupric ions in a variety of spiked samples of water like canal water, tap water, groundwater, distilled water. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Photothermal nanomaterials with near-infrared absorption and high energy conversion efficiency have recently attracted significant interest. Polypyrrole-gold nanocomposites (PPy-Au NCs) as photothermal nanoagents are synthesized using ex-situ polymerization method of the modified pyrrole monomers. Microscopic and spectroscopic characterization techniques are used to reveal the surface structure, composition variation and photoelectric properties of PPy-Au NCs, gold nanorods (Au NRs) and polypyyrole nanoparticles (PPy NPs). Their cytotoxic effects on the viability of Ehrlich Ascites Carcinoma cells in the dark are demonstrated. The surface coating of Au NRs with PPy NPs shows an enhancement in the photothermal efficiency of the proposed photothermal nanoagent. The photothermal conversion of nanomaterials are examined using polarized polychromatic incoherent low-energy light source (the energy density of the light is 2.4 J/cm(2) per minute and the specific power density is 40 mW/cm(2)). (C) 2021 Elsevier B.V. All rights reserved.
Darwish, Ibrahim A.Almehizia, Abdulrahman A.Sayed, Ahmed Y.Khalil, Nasr Y....
12页
查看更多>>摘要：Duvelisib (DUV) is a is a small-molecule with inhibitory action for phosphoinositide 3-kinase (PI3K). It has been recently approved for the effective treatment of chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). Novel charge transfer complex (CTC) between DUV, as electron donor, with chloranilic acid (CLA), as p electron acceptor has been synthesized and characterized using different spectroscopic and thermogravimetric techniques. UV-visible spectroscopy ascertained the formation of the CTC in different solvents of varying polarity indexes and dielectric constants via formation of new broad absorption band with maximum absorption peak (lambda(max)) in the range of 488-532 nm. The molar absorptivity of the CTC was dependent on the polarity index and dielectric constant of the solvent; the correlation coefficients were 0.9955 and 0.9749, respectively. The stoichiometric ratio of DUV:CLA was 1:1. Electronic spectral analysis was conducted for characterization of the complex in terms of its electronic constants. Computational calculation for atomic charges of energy minimized DUV was conducted and the site of interaction on DUV molecule was assigned. The solid-state CTC of DUV:CLA (1:1) was synthesized, and its structure was characterized by UV-visible, mass, FT-IR, and H-1 NMR spectroscopic techniques. Both FT-IR and H-1 NMR confirmed that both CT and hydrogen bonding contributed to the molecular composition of the complex. The reaction was adopted as a basis for developing a novel 96-microwell spectrophotometric assay (MW-SPA) for DUV. The assay limits of detection and quantitation were 0.57 and 1.72 mu g/well, respectively. The assay was validated and all validation parameters were acceptable. The method was implemented successfully with great precision and accuracy to the analysis of the DUV in its bulk and capsules. (C) 2021 Elsevier B.V. All rights reserved.
Gupta, PritiRahaman, FazlurGautam, PrabhatLekshmi, I. C....
7页
查看更多>>摘要：Thiazole based receptor 3, was designed and synthesized by condensation reaction of 5-chlorosalicy-laldehyde with 4-(4-phenylthiazol-2-yl)semicarbazide for colorimetric and fluorimetric detection of flu-oride ion. Receptor 3 was characterized by 1H NMR, 13C NMR, and HRMS, and shows absorption in 280- 400 nm region with emission at 442 nm in tetrahydrofuran (THF). Addition of fluoride ion to the THF solution of receptor 3 results in color change from colorless to yellow with significant change in UV- Visible absorption. The receptor-anion interaction occurs via hydrogen bonding followed by deprotona-tion which results in large bathochromic shift in absorption spectra and naked-eye color change. The col-orimetric changes show selective response for fluoride ions over other anions. Fluorescence studies exhibit remarkable enhancement in emission intensity upon addition of fluoride ion with a limit of detec-tion (LOD) of 8.6 nM. The 1H NMR titration studies exhibit deprotonation of the -OH proton of the sali-cylaldimine moiety resulting significant colorimetric and fluorimetric changes. (c) 2021 Elsevier B.V. All rights reserved.
S.Al-Otaibi, JamelahMary, Y. SheenaMary, Y. ShymaThomas, Renjith...
9页
查看更多>>摘要：Investigation of the adsorption properties croconic acid (CCA) with metal clusters (mC: Ag, Au and Cu) are reported using DFT method. CCA is found to form stable cluster with transition metal clusters of copper, silver and gold. The drug-cluster complexaton energy is slightly more for the copper nanocluster-drug complex. Non-covalent interaction analysis indicated that strong interactions and weak van der Waal interaction is present between drug and metal clusters. Dipole moment of the drug-gold cluster is found to be higher than that of the other systems. SERS studies demonstrates improved Raman signals for mul-tiple wavenumbers of all CCA-metal cluster complexes. Mulliken charge analysis show that all CCA oxy-gen atom's charge changes due to the interactions with the mCs. Clustering of CCA with metal cages enhances the medicinal properties and the metal nanoclusters will act as a drug carrier of CCA. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The computational simulation of the photoelectron spectrum of active form of vitamin B2 is reported in the gas phase. In this work, we determine relative stability of eight riboflavin conformers by conformational search first with molecular mechanics AMMP potential in VEGA software at 553 K. Relative abundance of conformers was deduced from Boltzmann population weighting method (BPW). The three most stable conformers were then selected for computing valence, vertical ionization energies. We used highlevel Equation-of-Motion Coupled-Cluster (EOM-IP-CCSD) method to obtain valence ionization energies (IP). In order to characterize the nature of ionization processes pertaining to different spectral bands, natural bonding orbital (NBO) method and molecular electrostatic potentials (MEP) were used to obtain orbital electron densities. The influence of the electronic structure of riboflavin on its biological activity is manifested via reduction of ionization energies of outermost orbitals which makes electron densities of these orbitals more readily available to participate in ligand-receptor bonding. (c) 2021 Elsevier B.V. All rights reserved.
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