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Facile fabrication of well-polarized Bi <sub/>2</sub> WO <sub/>6</sub> nanosheets with enhanced visible-light photocatalytic activity
摘要： Designing a templating strategy for directing mesopore growth along different crystallographic directions is essential for fabricating two- or three-dimensional single-crystalline mesoporous zeolites. However, so far, mesopores formed in MFI zeolites by soft templates have mostly been generated by disrupting growth along the b axis; generating mesopores by disrupting growth along the a axis is rare. Herein, a single-crystalline mesoporous MFI zeolite (SCMMZ) with sheet-like mesopores layered along the a and b axes was synthesized using a triply branched surfactant with diquaternary ammonium groups connected to 1,3,5-triphenylbenzene by a six- and eight-carbon alkyl chain (TPB-6 and 8). The sheet-like mesopores were embedded in the MFI framework and were retained even after calcination. Molecular mechanics calculations provided evidence of low binding energy configurations of the surfactant that directed the growth of straight and zigzag channels along the b and a axes, respectively. The formation of nanosheets was attributed to the geometric matching of the arrangement of the aromatic groups to the zeolite framework.
关键词： mesoporous zeolite,transmission electron microscopy,surfactants,self-assembly,MFI
更新于2025-09-19 17:15:36
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Photochemical Processes in Molecular Polymethine Dye Probes in the Presence of Bile Salts
摘要： Primary photochemical processes in polymethine dye probes 3,3′-di(γ-sulfopropyl)-4,5,4′,5′-dibenzo-9-ethylthiacarbocyanine betaine (DEC) and 3,3′,9-trimethylthiacarbocyanine iodide (Cyan 2) in micellar systems of bile-acid salts (BASs) sodium cholate, deoxycholate, and taurocholate and sodium dodecyl sulfate (SDS) as a reference are studied by flash photolysis. Signals due to photoisomerization of dye trans-isomers and dark reverse isomerization of the resulting cis-photoisomers are observed during pulse photolysis of air-saturated aqueous dye solutions in the presence of BAS and SDS micelles. The lifetimes of the photoisomers are 60–190 μs. Pulse photolysis of Cyan 2 and DEC solutions without oxygen and with BAS and SDS micelles induced photoisomerization and transition of the dyes into an excited triplet state followed by the reverse transition (intersystem crossing) into the initial singlet state. Triplet–triplet absorption spectra of these dyes isomers in polar (EtOH, i-PrOH) and nonpolar (dioxane) solvents were obtained for comparison using triplet–triplet energy transfer from anthracene. The conclusion was drawn that the photochemical behavior of the dyes in BAS and SDS micellar systems were similar.
关键词： triplet state,surfactants,polymethine dye probes,bile-acid salts,trans–cis photoisomerization,micelle
更新于2025-09-19 17:15:36
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Tuning the Porosity of TiO2 Nanoparticles via Surfactant-Templated Aerosol Process for Enhanced Photocatalytic Reactivity
摘要： In this work, we fabricated crystallite solid and porous TiO2 nanoparticles (NPs) using a surfactant-templated aerosol process. Specifically, Brij-58 surfactant was employed as a template in TiO2 matrix. The porosity of TiO2 NPs was controlled by varying the amount of Brij-58. The effect of TiO2 porosity on the photocatalytic reactivity was systematically examined. As a result, the highly porous TiO2 NPs exhibited much better photocatalytic reactivity than the low porosity TiO2 NPs. This suggests that the particle size, crystallite structure, and specific surface area play an important role in enhancing the photocatalytic reactivity of the TiO2 NPs.
关键词： surfactants,Aerosol process,photocatalysts,porous TiO2 nanoparticles,specific surface area
更新于2025-09-09 09:28:46
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Enhanced Quenching Effect of Neonicotinoid Pesticides on Time-Resolved Terbium Luminescence in Presence of Surfactants
摘要： A luminescence analytical method for the quantification of neonicotinoid pesticides (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid, and thiamethoxam) in water samples is proposed. The method is based on the quenching effect that these analytes produce on the time-resolved luminescence signal of terbium ions (excitation/emission wavelengths of 256/545 nm/nm). An enhancement on the analytical signal is observed when surfactants are used in the system. The use of a 0.01 mol·L?1 sodium dodecyl sulfate produced approximately a 30% increase in the sensitivity of the method. Under the optimum conditions, the method presented detection limits between 0.03 and 0.23 μg·mL?1. Interference studies were performed for ions commonly present in waters, observing no interferences. In addition, recovery experiments were performed in different waters, well, spring, and swamp, observing recovery yields close to 100%, with relative standard deviations lower than 4% in all cases. No sample treatment except a filtration step was required. Hence, this method may represent an alternative to other existing methods for the quick and simple analysis of these ubiquitous insecticides in environmental waters.
关键词： neonicotinoid pesticides,surfactants,time-resolved luminescence,terbium luminescence,water samples
更新于2025-09-04 15:30:14
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Effect of surfactants on the performance of 3D morphology W18O49 by solvothermal synthesis
摘要： Three-dimensional W18O49 nanostructures were synthesized by a solvothermal method using WCl6 as precursor and ethanol as solvent. The effects of surfactant on the crystalline phase and morphology of tungsten oxide were investigated. It was found that the photothermal conversion performance and the nanostructures were affected by the surfactant additives. The results of XRD, SEM, TEM, BET and XPS indicated that the addition of surfactant had no effect on the composition of the samples, while the morphology of the sample changed from the irregular massive structure to the uniform polygon, lamellar or nest structures. The results of DRS and heat resistance test showed that the film had excellent infrared shielding properties. The sample synthesized by the adding of cetyltrimethylammonium bromide (CTAB) surfactant showed only 34.04% transmittance in the infrared wavelength range, while the transmittance maintained at high level of 77.5% in the visible range. It reached to higher heat resistance of 6.5 °C under 1 h sunlight irradiation than other samples, the temperature change was only 41.7% of the blank test.
关键词： Nanometer W18O49 powder,Solvothermal synthesis,Morphology,Surfactants
更新于2025-09-04 15:30:14
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Chiral Analysis || Chiroptical Spectroscopic Studies on Soft Aggregates and Their Interactions
摘要： The word “aggregation” can encompass several situations ranging from two molecules coming together to form a dimeric structure [1] to several molecules coming together to form an organized assembly. Soft aggregates belong to the latter case where the varying number of molecules can come together to form a supramolecular assembly. This situation often occurs for surfactants (also popularly referred to as amphiphiles) [2], which contain both hydrophilic and hydrophobic groups in their chemical structures. Although there are a number of peptides that are known to aggregate, our focus in this chapter is limited to aggregates formed by surfactants. For a surfactant forming regular micellar structure in water, its molecules initially stay at the air–water interface because the hydrophobic part of surfactant molecules do not have enough affinity to mingle with water molecules. However, at a certain concentration, known as critical micelle concentration (CMC) or critical aggregation concentration (CAC), the air–water interface would have been filled up and surfactant molecules are forced to go into the water solvent. As a consequence, the surfactant molecules assemble together, inside the water solvent, in such a way that the hydrophobic portions of the surfactant molecules form their own interior surface facing away from water molecules. One classic example of these cases is sodium dodecyl sulfate (SDS), which when placed in water forms, above CMC, micellar structures with hydrophilic head groups pointing towards water and hydrophobic tails pointing away from water forming their own interior surface. A different example is Bis(2-ethylhexyl) sulfosuccinate sodium salt (also known as Aerosol-OT and abbreviated as AOT), which when dissolved in nonpolar solvents forms, above CMC, reverse micellar structures with hydrophobic tails pointing towards nonpolar solvent molecules and hydrophilic groups pointing away from the solvent forming their own interior surface. AOTs are known to encapsulate polar molecules, such as water, protecting them from unfavorable repulsive interactions with nonpolar solvent molecules. The assemblies, including micelles, reverse micelles, along with other possibilities such as lamellar, vesicles, ribbon, and rod-like structures [2] are referred to as soft aggregates.
关键词： micelles,critical micelle concentration,aggregation,surfactants,chiroptical spectroscopy
更新于2025-09-04 15:30:14
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Usage of Cellulose Diacetate as Sorption Material for Fluorescent Analysis of PAH
摘要： Solid-phase matrices made of cellulose diacetate (CDA) as films and fibers were prepared. The CDA film matrices were found to be characterized by a negative value of the surface potential (–32 ± 2 mV) while the fibers had positive ones (+419 ± 1 mV). The possibility of using these matrices as sorption materials for luminescence analysis of polycyclic hydrocarbons in water-ethanol and micellar media is shown. Modification of such polymeric CDA matrices with surfactants of various natures improves their sorptive capacity and hydrocarbon recovery, and increases the sensitivity of luminescent analysis.
关键词： Ethanolic media,Surfactants,Fluorescent analysis,Polycyclic aromatic hydrocarbons,Cellulose diacetate,Aqueous micellar solutions
更新于2025-09-04 15:30:14
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Modulation of Excited‐State Proton Transfer Dynamics Inside the Nanocavity of Microheterogeneous Systems: Microenvironment‐Sensitive F?rster Energy Transfer to Riboflavin
摘要： Excited-state proton transfer (ESPT) in a tetraarylpyrene derivative, 1,3,6,8-tetrakis(4-hydroxy-2,6-dimethylphenyl)pyrene (TDMPP), was investigated thoroughly in the presence of various surfactant assemblies such as micelles, vesicles, etc. The surfactants can significantly retard the extent of excited-state proton transfer process, resulting in a distinguishable optical signal compared to that in the bulk medium. Physical characteristics of the surfactant assemblies such as order, interfacial hydration and surface charge influence the proton transfer process, and allow multiparametric sensing. A higher degree of interfacial hydration facilitates the proton transfer process, while the positively charged head groups of the surfactants specifically stabilize the anionic form of the probe (TDMPP-O*). Further, Forster energy transfer from the probe to riboflavin was studied in phospholipid membrane, wherein the relative ratio of neutral vs anionic forms (TDMPP-OH/TDMPP-O*) was found to influence the extent of energy transfer. Overall, we demonstrate how an ultrafast photophysical process, that is, the excited-state proton transfer, can be influenced by microenvironment.
关键词： surfactants,Excited-state proton transfer,Energy transfer,microheterogeneous system,microenvironment
更新于2025-09-04 15:30:14
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http://www.orientjchem.org/vol34no1/optical-pattern-of-liquid-crystalline-structure-in-singular-and-mixed-anionic-cationic-surfactant-system/
摘要： A preliminary study to examine the liquid crystalline region formed by surfactant, DTAB and AOT, individually and mixed, in the presence of various chain length alcohols was carried out. Several ternary phase equilibrium were constructed. Results showed that all the investigated systems apart from forming lyotropic liquid crystalline structure were also able to form self-assembled aggregates such as micelle and reversed micelles. From the optical pattern observation, it was observed that two types of liquid crystalline were formed namely hexagonal and lamellar.
关键词： Optical pattern,Phase diagram,Surfactants
更新于2025-09-04 15:30:14