Co-macrocyclizations of 2,3-dipropylmaleonitrile and 2,3-di-(4-(methoxycarbonyl)phenyl)maleonitrile, respectively, with N,N′-dibenzyl-N,N′-di-(11-tetrahydropyranyloxy-3,6,9-trioxo-undecyl))maleonitrile and N,N,N′,N′-tetramethylmaleonitrile were used to prepare derivatives of the 4,5-diamino-porphyrazine systems including the zinc(II) complexes. Subsequent oxidation of the macrocycles with potassium permanganate gave the corresponding seco-porphyrazines. These were shown to be efficient sensitizers for the production of singlet oxygen (ΦΔ=0.15-0.57) by the determination of their photophysical properties. 相似文献
The syntheses, spectral UV–Vis, NMR, and electrochemical as well as photocatalytic properties of novel magnesium(II) and zinc(II) symmetrical sulfanyl porphyrazines with 2-(morpholin-4-yl)ethylsulfanyl peripheral substituents are presented. Both porphyrazine derivatives were synthesized in cyclotetramerization reactions and subsequently embedded on the surface of commercially available P25 titanium(IV) oxide nanoparticles. The obtained macrocyclic compounds were broadly characterized by ESI MS spectrometry, 1D and 2D NMR techniques, UV–Vis spectroscopy, and subjected to electrochemical studies. Both hybrid materials, consisting of porphyrazine derivatives embedded on the titanium(IV) oxide nanoparticles’ surface, were characterized in terms of particle size and distribution. Next, they were subjected to photocatalytic studies with 1,3-diphenylisobenzofuran, a known singlet oxygen quencher. The applicability of the obtained hybrid material consisting of titanium(IV) oxide P25 nanoparticles and magnesium(II) porphyrazine derivative was assessed in photocatalytic studies with selected active pharmaceutical ingredients, such as diclofenac sodium salt and ibuprofen. 相似文献
In this work, green synthesis of cobalt doped titanium dioxide (Co‐TiO2) has been carried out in aqueous medium using gelatin. The Co‐TiO2 particles have been characterized using transmission electron microscopy (TEM), X‐ray diffraction (XRD), energy dispersive X‐ray (EDAX), FT‐IR spectroscopy and voltammetry techniques. XRD results show pure Co‐TiO2 and TiO2 powders with average crystallite size about 12 nm and 15 nm, respectively. Co loaded in TiO2 hasn't influence crystalline structure. Moreover, efficient Co‐TiO2‐based anode was fabricated by casting of the Co‐TiO2 solution on glassy carbon electrode (Co‐TiO2/GCE). The electrocatalysis of oxygen evolution reaction (OER) at Co‐TiO2/GCE has been examined using linear scanning voltammetry (LSV) in alkaline media. The OER is significantly enhanced at Co‐TiO2/GCE, as demonstrated by a negative shift in the LSV curve at the Co‐TiO2/GCE compared to that obtained at the unmodified one. The value of energy saving of oxygen gas at a current density of 5 mA cm?2 is 12.6 kW h kg?1. The low cost as well as the marked stability of the modified electrode make it promising candidate in industrial water electrolysis process. 相似文献
1,4-Dihydropyridine and polyhydroquinoline derivatives have been prepared efficiently in a one-pot synthesis via Hantzsch condensation using nanosized titanium dioxide as a heterogeneous catalyst.The present methodology offers several advantages such as excellent yields,short reaction times (30-120 min),environmentally benign,and mild reaction conditions.The catalyst can be readily separated from the reaction products and recovered in excellent purity for direct reuse. 相似文献
Lanthanum doped mesoporous titanium dioxide photocatalysts with different La content were synthesized by template method using tetrabutyltitanate (Ti(OC4H9)4) as precursor and Pluronic P123 as template. The catalysts were characterized by thermogravimetric dif-ferential thermal analysis, N2 adsorption-desorption measurements, X-ray diffraction, and UV-Vis adsorption spectroscopy. The effect of La3+ doping concentration from 0.1% to 1% on the photocatalytic activity of mesoporous TiO2 was investigated. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of about 10 nm with high surface area of 165 m2/g. X-ray photoelectron spectroscopy measurements in-dicated the presence of C in the doped samples in addition to La. Compared with pure mesoporous TiO2, the La-doped samples extended the photoabsorption edge into the visible light region. The results of phenol photodecomposition showed that La-doped mesoporous TiO2 exhibited higher photocatalytic activities than pure mesoporous TiO2 under UV and visible light irradiation. 相似文献
We have established that as a result of both photochemical and reduction heat treatment of titanium dioxide preparations impregnated with transition metal salts, there is an increase in their catalytic efficiency in the process of copper deposition. We consider reactions leading to activation and deactivation of the catalysts. 相似文献
Summary: A novel class of polymer has been prepared by reaction of a copolyimide containing carboxylic acid groups, and a cobalt phthalocyanine peripherally substituted with a reactive hydroxyl group. The incorporation of the phthalocyanine ring was achieved by esterification of the carboxylic acid groups of the polyimide with the free hydroxyl group of the phthalocyanine. In this work, a limited number of phthalocyanine rings have been introduced in order to avoid extensive modification of the copolyimide properties. The extent of modification (percentage of esterified carboxylic groups) was estimated to be about 18%. The resulting material showed good thermal stability and a high glass transition temperature (above 300 °C). The incorporation of the bulky phthalocyanine ring brought about a light decrease of thermal properties, relative to those of the initial polyimide. The presence of phthalocyanine was confirmed by the absorption band at 670 nm showing in the visible region for the modified polyimide. The novel copolyimide also exhibited a remarkable emission peak at 430 nm, when excited at 350 nm, corresponding to the emission of the cobalt phthalocyanine moiety.
Schematic representation of the PI‐CoPc molecule and the chemical structure of the repeat unit. 相似文献
A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox-ide (TiO2) have been successfully prepared by template method using Fe(NO3)3·9H2O, La(NO3)3·6H2O, and tetrabutyl titanate as precursors and glucan as template. Scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption measurement were em-ployed to characterize the morphology, crystal structure and surface structure of the samples. The photo-absorbance of the obtained catalysts was measured by UV-Vis absorption spec-troscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange in an aqueous solu-tion. The characterizations indicated that the prepared photocatalysts consisted of anatase phase and possessed high surface area of ca. 163-176 m2/g. It was shown that the Fe and La co-doped nano-TiO2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The synergistic effect of Fe and La co-doping played an important role in improving the photocatalytic activity. In addition, the possibil-ity of cyclic usage of co-doped nano-TiO2 was also confirmed, the photocatalytic activity of codoped nano-TiO2 remained above 89.6% of the fresh sample after being used four times. 相似文献
Agriculture is the backbone of every developing country. Among various crops, wheat (Triticum aestivum L.) belongs to the family Poaceae and is the most important staple food crop of various countries. Different biotic (viruses, bacteria and fungi) and abiotic stresses (water logging, drought and salinity) adversely affect the qualitative and quantitative attributes of wheat. Among these stresses, salinity stress is a very important limiting factor affecting the morphological, physiological, biochemical attributes and grain yield of wheat. This research work was carried out to evaluate the influence of phytosynthesized TiO2 NPs on the germination, physiochemical, and yield attributes of wheat varieties in response to salinity. TiO2 NPs were synthesized using TiO2 salt and a Buddleja asiatica plant extract as a reducing and capping agent. Various concentrations of TiO2 nanoparticles (20, 40, 60 and 80 mg/L) and salt solutions (NaCl) (100 and 150 mM) were used. A total of 20 mg/L and 40 mg/L improve germination attributes, osmotic and water potential, carotenoid, total phenolic, and flavonoid content, soluble sugar and proteins, proline and amino acid content, superoxide dismutase activity, and reduce malondialdhehyde (MDA) content at both levels of salinity. These two concentrations also improved the yield attributes of wheat varieties at both salinity levels. The best results were observed at 40 mg/L of TiO2 NPs at both salinity levels. However, the highest concentrations (60 and 80 mg/L) of TiO2 NPs showed negative effects on germination, physiochemical and yield characteristics and causes stress in both wheat varieties under control irrigation conditions and salinity stress. Therefore, in conclusion, the findings of this research are that the foliar application of TiO2 NPs can help to improve tolerance against salinity stress in plants. 相似文献
The synthesis of ruthenium(II) phthalocyanines (RuPcs) endowed with one carbohydrate unit—that is, glucose, galactose and mannose—and a dimethylsulfoxide (DMSO) ligand at the two axial coordination sites, respectively, is described. Two series of compounds, one unsubstituted at the periphery, and the other one bearing eight PEG chains at the isoindole meta-positions, have been prepared. The presence of the axial DMSO unit significantly increases the phthalocyanine singlet oxygen quantum yields, related to other comparable RuPcs. The compounds have been evaluated for PDT treatment in bladder cancer cells. In vitro studies have revealed high phototoxicity for RuPcs unsubstituted at their periphery. The phototoxicity of PEG-substituted RuPcs has been considerably improved by repeated light irradiation. The choice of the axial carbohydrate introduced little differences in the cellular uptake for both series of photosensitizers, but the phototoxic effects were considerably higher for compounds bearing mannose units. 相似文献
We report here the synthesis of binderless and template-less three-dimensional (3D) pinecone-shaped Pt/TiO2/Ti mesh structure. The TiO2 hydrothermally synthesized onto Ti mesh is composed of a mixture of flower-like nanorods and vertically aligned bar-shaped structures, whereas Pt film grown by pulsed laser deposition displays a smooth surface. XRD analyses reveal an average crystallite size of 41.4 nm and 68.5 nm of the TiO2 nanorods and Pt, respectively. In H2SO4 solution, the platinum oxide formation at the Pt/TiO2/Ti mesh electrode is 180 mV more negative than that at the Pt/Ti mesh electrode, indicating that TiO2 provides oxygeneous species at lower potentials, which will facilitate the removal of CO-like intermediates and accelerate an ethanol oxidation reaction (EOR). Indeed, the Pt/TiO2/Ti mesh catalyst exhibits current activity of 1.19 mA towards an EOR at a remarkably superior rate of 4.4 times that of the Pt/Ti mesh electrode (0.27 mA). Moreover, the presence of TiO2 as a support to Pt delivers a steady-state current of 2.1 mA, with an increment in durability of 6.6 times compared to Pt/Ti mesh (0.32 mA). Pt is chosen here as a benchmark catalyst and we believe that with catalysts that perform better than Pt, such 3D pinecone structures can be useful for a variety of catalytic or photoelectrochemical reactions. 相似文献
In the context of gaining understanding on the origin of the visible‐light photoresponse of TiO2 containing gold nanoparticles, the photocurrent spectra and photocatalytic H2 evolution of titania (P25) and Au–P25 were compared. Whereas no photocurrent was detected upon visible‐light irradiation for either of the two photocatalysts, Au–P25 exhibited photocatalytic H2 evolution for wavelengths between 400 and 575 nm. This contradictory behavior under visible‐light irradiation of Au–P25 was rationalized by transient absorption spectroscopy. It was suggested that photocatalytic H2 generation results from methanol quenching of the charge‐separation state in each semiconductor nanoparticle, but the lack of photocurrent is due to the short lifetime of the charge separation, which makes interparticle charge migration for micrometric distances unlikely. 相似文献
A series of novel iodinated NO2‐substituted aza‐BODIPYs have been synthesized and characterized. Highly desirable photophysical and photochemical properties were induced in NO2‐substituted aza‐BODIPYs by iodination of the pyrrole rings. In particular, high values of singlet oxygen quantum yields (ΦΔ) ranging from 0.79 to 0.85 were measured. The photooxygenation process proceeds via a Type II mechanism under the experimental conditions applied. The compounds studied exhibited an absorption band within the so‐called “therapeutic window”, with λmax located between 645 nm to 672 nm. They were non‐fluorescent at room temperature with excited singlet‐state lifetimes within the picosecond range as measured by femtosecond transient absorption. Nanosecond laser flash photolysis experiments revealed T1→Tn absorption spanning from ca. 400 nm to ca. 500 nm and allowed determination of the triplet‐state lifetimes. The estimated triplet lifetimes (τT) in deaerated acetonitrile ranged between 2.74 μs and 3.50 μs. As estimated by CV/DPV measurements, all iodinated aza‐BODIPYs studied exhibited one irreversible oxidation and two quasi‐reversible reductions processes. Estimation of the EHOMO gave the value of ?6.06 to ?6.26 eV while the ELUMO was found to be located at ca. ?4.6 eV. Thermogravimetric (TGA) analysis revealed that iodinated aza‐BODIPYs were stable up to approximately 300 °C. All compounds studied exhibit high photostability in toluene solution. 相似文献
Using a new mononuclear “building block,” for the first time, a dinuclear RuII(dppn) complex and a heteroleptic system containing both RuII(dppz) and RuII(dppn) moieties are reported. The complexes, including the mixed dppz/dppn system, are 1O2 sensitizers. However, unlike the homoleptic dppn systems, the mixed dppz/dppn complex also displays a luminescence “switch on” DNA light‐switch effect. In both cisplatin sensitive and resistant human ovarian carcinoma lines the dinuclear complexes show enhanced uptake compared to their mononuclear analogue. Thanks to a favorable combination of singlet oxygen generation and cellular uptake properties all three of the new complexes are phototoxic and display potent activity against chemotherapeutically resistant cells. 相似文献
New carriers of phytosterols; acylglycerols containing natural myristic acid at sn-1 and sn-3 positions and stigmasterol residue linked to sn-2 position by carbonate and succinate linker have been designed and synthesized in three-step synthesis from dihydroxyacetone (DHA). The synthetic pathway involved Steglich esterification of DHA with myristic acid; reduction of carbonyl group of 1,3-dimyristoylpropanone and esterification of 1,3-dimyristoylglicerol with stigmasterol chloroformate or stigmasterol hemisuccinate. The structure of the obtained hybrids was established by the spectroscopic methods (NMR; IR; HRMS). Obtained hybrid molecules were used to form new liposomes in the mixture with model phospholipid and their effect on their physicochemical properties was determined, including the polarity, fluidity, and main phase transition of liposomes using differential scanning calorimetry and fluorimetric methods. The results confirm the significant effect of both stigmasterol-containing acylglycerols on the hydrophilic and hydrophobic region of liposome membranes. They significantly increase the order in the polar heads of the lipid bilayer and increase the rigidity in the hydrophobic region. Moreover, the presence of both acylglycerols in the membranes shifts the temperature of the main phase transition towards higher temperatures. Our results indicate stabilization of the bilayer over a wide temperature range (above and below the phase transition temperature), which in addition to the beneficial effects of phytosterols on human health makes them more attractive components of novel lipid nanocarriers compared to cholesterol. 相似文献