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Development of a nanoscale-based optical chemical sensor for the detection of NO radical
摘要： Nitric oxide is one of the most important biochemical parameters in biological processes; it is also known as carcinogenic. There is need for the design of stable and durable solid phase nitric oxide sensors. In this study, we immobilized the nitric oxide sensitive molecules pyrene, tris(2,2’-bipyrdyl)dichlororuthenium(II) hexahydrate (Ru(bipy) 2+ 3 ) , and magnesium phthalocyanine (Mg-Pc) for the first time in polymeric or glassy matrices. We applied silver nanoparticles and ionic liquids in the fabrication process of polymeric electrospun fibers and thin films. We compared their NO sensitivity in micelle solutions that mimic the cell medium by both steady state and lifetime-based fluorescence measurements. Among the tested dyes, the pyrene exhibited the highest response for radicalic NO. The Mg-Pc dye followed pyrene in terms of sensitivity and exhibited increasing fluorescence intensity and lifetime-based response. Lifetime-based response is advantageous and selective as it is not affected by source variations, photo-bleaching, or leaching effects. Another advantage of Mg-Pc dye is that it is not poisonous for organic systems. Presence of the ionic liquid enhanced the sensor response in all of the test moieties. The obtained limit of detection values for pyrene, Ru(bipy) 2+ and Mg-Pc dyes were 0.15 (cid:22) M, 1.54 (cid:22) M, and 0.78 (cid:22) M, respectively.
关键词： electrospinning,Nitric oxide radical,nanomaterials,ruthenium complex,magnesium phthalocyanine,pyrene,time resolved fluorescence
更新于2025-09-04 15:30:14
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Polydopamine‐coated poly(vinylidene fluoride) membranes with high ultraviolet resistance and antifouling properties for a photocatalytic membrane reactor
摘要： We modi?ed poly(vinylidene ?uoride) (PVDF) membranes with a polydopamine (PDA) coating for photocatalytic membrane reactor application with appropriate UV resistance and studied the effects of the PDA coating conditions (i.e., coating time and dopamine concentration) and UV irradiation time on the modi?ed PVDF membrane properties. The PVDF membrane that was surface-coated with the appropriate dopamine solution concentration and coating time played a key role in controlling the membrane properties and in protecting the modi?ed membrane against UV radiation. The optimization of the coating condition not only completely protected the modi?ed membrane from free-radical attack initiated through UV irradiation but also improved the membrane hydrophilicity, antifouling properties, ?ltration performance, and mechanical strength of the membrane. UV irradiation of the membrane that was surface-coated with a high-concentration dopamine solution for a long coating time resulted in a higher mechanical strength than that of the membrane without the application of UV irradiation.
关键词： free radical scavenger,photocatalytic membrane reactor,polydopamine,UV-resistance
更新于2025-09-04 15:30:14
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Effect of excess electron on structure, bonding, and spectral properties of sulfur/selenium based dichalcogen systems
摘要： First principle based quantum chemical methods are employed to characterize structure, bonding, and spectral properties of sulfur and selenium based dichalcogen systems in presence of an excess electron. Inter molecular two-center three-electron (2c-3e) bonding between two chalcogen (X) atoms is described in the systems of the type (R-X)2?- (R = Ph, PhCH2 X = S, Se). In addition, effect of electron withdrawing (-NO2) and electron donating (-CH3) groups in phenyl ring on the stability of these 2c-3e bonded systems is also studied in water medium applying a macroscopic hydration model. Molecular parameters and binding energy of the neutral, (R-X)2 and reduced, (R-X)2?- dichalcogen systems are compared. Search for minimum energy structures of these open shell doublet systems are carried out applying various density functionals with dispersion corrections and MP2 method considering 6-311++G (d,p) set of basis functions for all atoms. Effect of water medium is introduced through a macroscopic solvation model based on density (SMD). Frontier molecular orbitals based analysis is carried out for showing the definite presence of 2c-3e bond between two chalcogen atoms in these radical anions of sulfur and selenium based aromatic dichalcogen systems. Excited state calculations are performed on all these systems using Time Dependent Density Functional Theory (TDDFT). UV-Vis spectra are simulated and effect of solvent water on the absorption maximum of these radical anions is discussed. This study illustrates that the combination of electronic effect and geometrical flexibility decides the strength of two-center three-electron bond in these systems.
关键词： sulfur,hemi bond,radical anion,density functional theory,chalcogen,excess electron,2c-3e bond,antioxidant,selenium
更新于2025-09-04 15:30:14
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Advanced oxidation of formaldehyde in aqueous solution using the chemical-less UVC/VUV process: Kinetics and mechanism evaluation
摘要： This study was conducted to evaluate the degradation of high concentrations of formaldehyde in the chemical-less UVC/VUV photo-reactor. 99.5% degradation and 94% chemical oxygen demand (COD) removal of 200 mg/L formaldehyde was achieved in the UVC/VUV photo-reactor at reaction time of 60 min and solution pH of 7. The effect of water anions such as carbonate, bicarbonate, nitrate, chloride, sulfate and phosphate was examined on degradation and COD removal of formaldehyde; nitrate and carbonate exhibited the highest inhibitory effects on the process. Besides, treatment of formaldehyde-contaminated tap water was also investigated and formaldehyde removal was decreased from 99.5% is aqueous solution to 86.2% in tap water. The findings of radical scavenging tests revealed that hydroxyl radical was the most predominant oxidizing agent contributed in degradation of formaldehyde. It is concluded therefore that the UVC/VUV process as a unique chemical-less process efficient for advanced degradation of high concentrations of formaldehyde.
关键词： Hydroxyl radical,COD removal,Vacuum UV,Formaldehyde degradation,Advanced photo-oxidation
更新于2025-09-04 15:30:14
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Highly Efficient Fluorescent Organic Light-Emitting Devices Using a Luminescent Radical as the Sensitizer
摘要： In traditional fluorescent organic light-emitting diodes (OLEDs), the upper limit of internal quantum efficiency (IQE) is only 25% because 75 % triplet excitons created on the fluorescent dyes are non-luminous. Here, luminescent radicals are proposed as the sensitizer. Under ideal conditions, electrons and holes firstly recombine on the sensitizer molecule to create doublet excitons, then through energy transfer to generate singlet excitons on the fluorescent dye, finally via radiative decay to emit light. The upper limit of IQE can theoretically reach 100%. As an example, the maximum external quantum efficiency (EQE) of a fluorescent OLED sensitized by a luminescent radical, TTM-1Cz, has reached 8.1%, which is much higher than the upper limit of EQE of traditional fluorensenct OLEDs. Our results suggest a new route to realize highly efficient fluorescent OLEDs.
关键词： organic light-emitting device,doublet,luminescent radical,sensitize,deep-red
更新于2025-09-04 15:30:14