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The Journal of Physical Chemistry... Jun 2024Organic materials that can emit ultralong room-temperature phosphorescence (RTP) have attracted a great deal of interest. Whether the pure boric acid (BA) solid can emit...
Organic materials that can emit ultralong room-temperature phosphorescence (RTP) have attracted a great deal of interest. Whether the pure boric acid (BA) solid can emit RTP and the origin of the RTP in BA caused a debate recently. Herein, our first-principles calculations and experimental measurements suggest that RTP of BA originates from the B-O-O-B group in a (HBO) species, which can be formed by polymerization of two dehydrogenated BA molecules under light irradiation. The calculated absorption, fluorescence, and phosphorescence spectra of B-O-O-B match well with the experiments. Experimental X-ray photoelectron and X-ray absorption spectra evidence the existence of B-O-O-B in BA. The O-O bond in B-O-O-B can break upon optical excitation, creating two B-O radicals. Radiative transition from localized dangling orbitals of the B-O radicals to the delocalized orbitals of the crystal bulk leads to the observed RTP. Our calculated phosphorescence lifetime is ∼1 s, which agrees well with the experiment.
PubMed: 38934585
DOI: 10.1021/acs.jpclett.4c01354 -
Materials (Basel, Switzerland) Jun 2024Hybrid organic-inorganic lead halide perovskites (LHPs) have emerged as a highly significant class of materials due to their tunable and adaptable properties, which make...
Hybrid organic-inorganic lead halide perovskites (LHPs) have emerged as a highly significant class of materials due to their tunable and adaptable properties, which make them suitable for a wide range of applications. One of the strategies for tuning and optimizing LHP-based devices is the substitution of cations and/or anions in LHPs. The impact of Cs substitution at the A site on the structural, vibrational, and elastic properties of MACsPbCl-mixed single crystals was investigated using X-ray diffraction (XRD) and Raman and Brillouin light scattering techniques. The XRD results confirmed the successful synthesis of impurity-free single crystals, which exhibited a phase coexistence of dominant cubic and minor orthorhombic symmetries. Raman spectroscopy was used to analyze the vibrational modes associated with the PbCl octahedra and the A-site cation movements, thereby revealing the influence of cesium incorporation on the lattice dynamics. Brillouin spectroscopy was employed to investigate the changes in elastic properties resulting from the Cs substitution. The incorporation of Cs cations induced lattice distortions within the inorganic framework, disrupting the hydrogen bonding between the MA cations and PbCl octahedra, which in turn affected the elastic constants and the sound velocities. The substitution of the MA cations with smaller Cs cations resulted in a stiffer lattice structure, with the two elastic constants increasing up to a Cs content of 30%. The current findings facilitate a fundamental understanding of mixed lead chloride perovskite materials, providing valuable insights into their structural and vibrational properties.
PubMed: 38930231
DOI: 10.3390/ma17122862 -
ACS Applied Materials & Interfaces Jun 2024To learn more about the behavior of amine (NH)-functionalized metal-organic framework (MOF)-derived noble metal catalysts in the removal of aromatic volatile organic...
To learn more about the behavior of amine (NH)-functionalized metal-organic framework (MOF)-derived noble metal catalysts in the removal of aromatic volatile organic compounds in air, benzene oxidation at low temperatures has been investigated using 0.2-, 0.8-, and 1.5%-platinum (Pt)/Universitetet i Oslo (UiO)-66-NH. The benzene conversion () of %-Pt/UiO-66-NH-R under dry conditions (175 °C) was 23% ( = 0.2%) < 52% ( = 0.8%) < 100% ( = 1.5%): 'R' suffix denotes reduction pretreatment using a hydrogen (10 vol %) and nitrogen mixture at 300 °C for the generation of metallic Pt (Pt) sites and simultaneous partial MOF decomposition into carbon- and nitrogen-loaded zirconium dioxide. The prominent role of reduction pretreatment was apparent in benzene oxidation as 1.5%-Pt/UiO-66-NH did not exhibit catalytic activity below 175 °C (dry condition). The promotional role of moisture in benzene oxidation by 1.5%-Pt/UiO-66-NH-R was evident with a rise in the steady-state reaction rate () at 110 °C (21 kPa molecular oxygen (O)) from 1.3 × 10 to 5.0 × 10 μmol g s as the water (HO) partial pressure increased from 0 to 1.88 kPa. In contrast, the activity was lowered with increasing RH due to catalyst poisoning by excess moisture ( (110 °C) of 6.6 × 10 μmol g s at 2.83 kPa HO (21 kPa O)). Kinetic modeling suggests that X proceeds through the Langmuir-Hinshelwood mechanism on the Pt/UiO-66-NH-R surface (dissociative O chemisorption and the involvement of two oxygen species in benzene oxidation). According to the density functional theory simulation, the carbon and nitrogen impurities are to make the first step (i.e., hydrogen migration from the benzene molecule to the substrate) energetically favorable. The second hydrogen atom from the benzene molecule is also extracted effectively, while the oxygen derived from O facilitates further . The Pt sites dissociate the O and HO molecules, while the product of the latter, i.e., free hydrogen and hydroxyl, makes the subsequent steps energetically favorable.
PubMed: 38912904
DOI: 10.1021/acsami.4c07188 -
Angewandte Chemie (International Ed. in... Jun 2024Water in hydrophobic nanospaces shows specific dynamic properties different from bulk water. The investigation of these properties is important in various research...
Water in hydrophobic nanospaces shows specific dynamic properties different from bulk water. The investigation of these properties is important in various research fields, including materials science, chemistry, and biology. The elucidation of the correlation between properties of water and hydrophobic nanospaces requires nanospaces covered only with simple hydrophobic group (e.g., fluorine) without impurities such as metals. This work successfully fabricated all-organic diamondoid porous organic salts (d-POSs) with highly fluorinated nanospaces, wherein hydrophobic fluorine atoms are densely exposed on the void surfaces, by combining fluorine substituted triphenylmethylamine (TPMA) derivatives with tetrahedral tetrasulfonic acid. This d-POSs with a highly fluorinated nanospace significantly improved their water stability, retaining their crystal structure even when immersed in water over one week. Moreover, this highly hydrophobic and fluorinated nanospace adsorbs 160 mL(STP)/g of water vapor at Pe/P0 = 0.90; this is the first hydrophobic nanospace, which water molecules can enter, in an all-organic porous material. Furthermore, this highly fluorinated nanospace exhibits very high proton conductivity (1.34 × 10-2 S/cm) at 90°C and 95%RH. POSs with tailorable nanospaces may significantly advance the elucidation of the properties of specific "water" in pure hydrophobic environments.
PubMed: 38899387
DOI: 10.1002/anie.202407484 -
Foods (Basel, Switzerland) May 2024Bixin is the main carotenoid found in the outer portion of the seeds of L., commercially known as annatto. This compound is industrially employed in pharmaceutical,...
Bixin is the main carotenoid found in the outer portion of the seeds of L., commercially known as annatto. This compound is industrially employed in pharmaceutical, cosmetic, and food formulations as a natural dye to replace chemical additives. This study aimed to extract bixin from annatto seeds and obtain encapsulated bixin in a powder form, using freeze-drying encapsulation and maltodextrin as encapsulating agent. Bixin was extracted from annatto seeds employing successive washing with organic solvents, specifically hexane and methanol (1:1 /), followed by ethyl acetate and dichloromethane for subsequent washes, to effectively remove impurities and enhance bixin purity, and subsequent purification by crystallization, reaching 1.5 ± 0.2% yield (or approximately 15 mg of bixin per gram of seeds). Bixin was analyzed spectrophotometrically in different organic solvents (ethanol, isopropyl alcohol, dimethylsulfoxide, chloroform, hexane), and the solvents chosen were chloroform (used to solubilize bixin during microencapsulation) and hexane (used for spectrophotometric determination of bixin). Bixin was encapsulated according to a 2 experimental design to investigate the influence of the concentration of maltodextrin (20 to 40%) and bixin-to-matrix ratio (1:20 to 1:40) on the encapsulation efficiency (EE%) and solubility of the encapsulated powder. Higher encapsulation efficiency was obtained at a maltodextrin concentration of 40% / and a bixin/maltodextrin ratio of 1:20, while higher solubility was observed at a maltodextrin concentration of 20% / for the same bixin/maltodextrin ratio. The encapsulation of this carotenoid by means of freeze-drying is thus recognized as an innovative and promising approach to improve its stability for further processing in pharmaceutical and food applications.
PubMed: 38890850
DOI: 10.3390/foods13111622 -
Chemistry of Materials : a Publication... Jun 2024The effects of impurities on reaction precursors for metal-organic framework (MOF) synthesis have not been studied in extensive detail. The impact of these impurities...
The effects of impurities on reaction precursors for metal-organic framework (MOF) synthesis have not been studied in extensive detail. The impact of these impurities can be an important factor while considering scale-up of these materials. In this work, we study the apparently positive impact of the presence of manganese ions for the synthesis of a Co-based MOF, Massey University Framework-16 (MUF-16). The presence of a trace amount of manganese in the reaction mixture led to consistently high CO uptake across multiple batches. Characterization including X-ray diffraction, scanning electron microscopy, Fourier transform infrared-attenuated total reflectance, ultraviolet-visible spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure spectroscopy led us to hypothesize that the differences in CO adsorption among materials with differing synthesis routes arise from variations in the local environment around the cobalt metal center. Aided by density functional theory calculations, we speculate that manganese ions get inserted into the structure during crystallization and act as catalysts for ligand substitution, improving the possibility for octahedral coordination of cobalt with the ligand, thus leading to Co-based pristine structures with higher CO uptakes.
PubMed: 38883436
DOI: 10.1021/acs.chemmater.4c00137 -
Journal of Pharmaceutical and... Jun 2024Omeprazole (OME) is a proton pump inhibitor used to treat gastroesophageal reflux disease associated conditions. The current study presents an Analytical Quality by...
Omeprazole (OME) is a proton pump inhibitor used to treat gastroesophageal reflux disease associated conditions. The current study presents an Analytical Quality by Design-based approach for the development of a CE method for OME impurity profiling. The scouting experiments suggested the selection of solvent modified Micellar ElectroKinetic Chromatography operative mode using a pseudostationary phase composed of sodium dodecyl sulfate (SDS) micelles and n-butanol as organic modifier in borate buffer. A symmetric three-level screening matrix 3//16 was used to evaluate the effect of Critical Method Parameters, including Background Electrolyte composition and instrumental settings, on Critical Method Attributes (critical resolution values, OME peak width and analysis time). The analytical procedure was optimized using Response Surface Methodology through a Central Composite Orthogonal Design. Risk of failure maps made it possible to define the Method Operable Design Region, within which the following optimized conditions were selected: 72 mM borate buffer pH 10.0, 96 mM SDS, 1.45 %v/v n-butanol, capillary temperature 21 °C, applied voltage 25 kV. The method was validated according to ICH guidelines and robustness was evaluated using a Plackett-Burman design. The developed procedure enables the simultaneous determination of OME and seven related impurities, and has been successfully applied to the analysis of pharmaceutical formulations.
PubMed: 38879949
DOI: 10.1016/j.jpba.2024.116295 -
Scientific Reports Jun 2024A series of 4-ferrcenylbutyl carboxylate esters with different alkyl chain length (C-C) of carboxylic acids were synthesized using FeO@SiO@(CH)-Im-bisEthylFc[I]...
A series of 4-ferrcenylbutyl carboxylate esters with different alkyl chain length (C-C) of carboxylic acids were synthesized using FeO@SiO@(CH)-Im-bisEthylFc[I] nanoparticles as catalyst and have been characterized with FT-IR, H NMR, and C NMR. Ferrocenyl-based esters were used as corrosion inhibitors of mild steel in the 1M HCl solution as corrosive media. The corrosion inhibition efficiency of the synthesized ferrocenyl-based esters has been assessed by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The 4-ferrocenylbutyl propionate showed a more effective corrosion inhibition behavior among the studied esters with 96% efficiency after immersion in the corrosive media for 2 weeks. The corrosion inhibition mechanism is dominated by formation of passive layer of inhibitor on the surface of the mild steel by adsorption. Moreover, the adsorption characteristics of 4-butylferrcenyl carboxylate esters on mild steel were thoroughly explored using density functional theory calculations. It was found that the Fe atoms located around the C impurity in the mild steel are the most efficient and active sites to adsorb 4-butylferrcenyl carboxylate esters.
PubMed: 38879584
DOI: 10.1038/s41598-024-64471-0 -
Journal of the Air & Waste Management... Jun 2024The disposal of spent bleaching clay from vegetable oil refining industries has been recognized as a significant environmental issue. After adsorbing the impurities,...
The disposal of spent bleaching clay from vegetable oil refining industries has been recognized as a significant environmental issue. After adsorbing the impurities, spent bleaching clay becomes contaminated with a high concentration of organic and inorganic substances, including residual oils, fatty acids, phospholipids, and potentially toxic heavy metals. This makes spent bleaching clay a hazardous waste and improper disposal can lead to severe environmental consequences. Due to the potential environmental harm caused by spent bleaching clay disposal, it is crucial for vegetable oil refining industries to adopt proper waste management practices. Overall, the proper management and disposal of spent bleaching clay is essential to prevent environmental contamination and safeguard human health.
PubMed: 38874942
DOI: 10.1080/10962247.2024.2365715 -
Nano Letters Jun 2024Disease biomarkers in tears are crucial for clinical diagnosis and health monitoring. However, the limited volume of tear samples, low concentration of tear biomarkers,...
Disease biomarkers in tears are crucial for clinical diagnosis and health monitoring. However, the limited volume of tear samples, low concentration of tear biomarkers, and complex tear composition present challenges for precise testing. We introduce a spot-on testing platform of metal-organic framework (MOF)-based surface-enhanced Raman scattering (SERS) capillary column, which is capable of target molecules selective separation and enrichment for tear biomarkers detection. It consists of Au nanostars for effective SERS signal and a porous MOF shell for separating impurities through molecular sieving effect. This platform allows for simultaneous collection and detection of tear, capturing the disease biomarker malondialdehyde in tears with a 9.38 × 10 mol/L limit of detection. Moreover, we designed a hand-held device based on this tubular SERS sensor, successfully diagnosing patients with dry eye disease. This functional capillary column enables noninvasive and rapid diagnosis of biomarkers in biofluids, providing potential for disease diagnosis and healthcare monitoring.
Topics: Spectrum Analysis, Raman; Tears; Metal-Organic Frameworks; Humans; Malondialdehyde; Gold; Biomarkers; Dry Eye Syndromes; Limit of Detection; Metal Nanoparticles
PubMed: 38860501
DOI: 10.1021/acs.nanolett.4c01978