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991.
James Charles Truscott Jeanet Conradie Hendrik C. Swart Mart-Marie Duvenhage Hendrik Gideon Visser 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(8):1045-1052
Single crystals of the aluminium and gallium complexes of 6,6′‐{(1E,1′E)‐[1,2‐phenylenebis(azanylylidene)]bis(methanylylidene)}bis(2‐methoxyphenol), namely diaqua(6,6′‐{(1E,1′E)‐[1,2‐phenylenebis(azanylylidene)]bis(methanylylidene)}bis(2‐methoxyphenolato)‐κ4O1,N,N′,O1′)aluminium(III) nitrate ethanol monosolvate, [Al(C22H18N2O4)(H2O)2]NO3·C2H5OH, 1 , and diaqua(6,6′‐{(1E,1′E)‐[1,2‐phenylenebis(azanylylidene)]bis(methanylylidene)}bis(2‐methoxyphenolato)‐κ4O1,N,N′,O1′)gallium(III) nitrate ethanol monosolvate, [Ga(C22H18N2O4)(H2O)2]NO3·C2H5OH, 2 , were obtained after successful synthesis in ethanol. Both complexes crystallized in the triclinic space group P, with two molecules in the asymmetric unit. In both structures, in one of the independent molecules the tetradentate ligand is almost planar while in the other independent molecule the ligand shows significant distortions from planarity, as illustrated by the largest distance from the plane constructed through the central metal atom and the O,N,N′,O′‐coordinating atoms of the ligand in 1 of 1.155 (3) Å and a distance of 1.1707 (3) Å in 2 . The possible reason for this is that there are various strong π‐interactions in the structures. This was confirmed by density functional theory (DFT) calculations, as were the other crystallographic data. DFT was also used to predict the outcome of cyclic voltammetry experiments. Ligand oxidation is more stabilized in the gallium complex. Solid‐state photoluminescence gave an 80 nm red‐shifted spectrum for the gallium complex, whereas the aluminium complex maintains the ligand curve with a smaller red shift of 40 nm. 相似文献
992.
Svechnikov S. V. Pokhodenko V. D. Guba N. F. Fenenko L. I. Smertenko P. S. Prokopenko I. V. Grebinskaya L. N. Lytvyn P. M. Piryatinskii Yu. P. Lytvyn O. P. Ol'khovik G. P. 《Russian Journal of Electrochemistry》2004,40(3):259-266
Films of nanosized composites of poly(N-epoxypropylcarbazole) (pEPC) and poly(3,6-di-Br-N-epoxypropylcarbazole) (pdBEPC) with vanadium pentoxide (V2O5) are produced for the first time ever. The electroconduction in dark and when illuminated, absorption spectra, steady-state photoluminescence spectra, and time-resolved photoluminescence spectra for the composite films are studied. The results are compared with relevant data for the pEPC, pdBEPC, and V2O5films. A conclusion about the formation of donor–acceptor complexes with incomplete charge transfer [pEPC+···V2O
5
-
] and [pdBEPC+···V2O5
-] is made. The surface morphology of the composites differs in the size of V2O5 fibers and polymer grains; the polymer inclusions in the composites are of different character. A surface morphology study reveals that the composite constituents—polymer base and V2O5 fibers—are nanosized. 相似文献
993.
994.
Large‐Scale Synthesis of Highly Luminescent Perovskite‐Related CsPb2Br5 Nanoplatelets and Their Fast Anion Exchange 下载免费PDF全文
Kun‐Hua Wang Liang Wu Lei Li Prof. Dr. Hong‐Bin Yao Prof. Dr. Hai‐Sheng Qian Prof. Dr. Shu‐Hong Yu 《Angewandte Chemie (International ed. in English)》2016,55(29):8328-8332
All‐inorganic cesium lead‐halide perovskite nanocrystals have emerged as attractive optoelectronic nanomaterials owing to their stabilities and highly efficient photoluminescence. Herein we report a new type of highly luminescent perovskite‐related CsPb2Br5 nanoplatelets synthesized by a facile precipitation reaction. The layered crystal structure of CsPb2Br5 promoted an anisotropic two‐dimensional (2D) crystal growth during the precipitation process, thus enabling the large‐scale synthesis of CsPb2Br5 nanoplatelets. Fast anion exchange has also been demonstrated in as‐synthesized CsPb2Br5 nanoplatelets to extend their photoluminescence spectra to the entire visible spectral region. The large‐scale synthesis and optical tunability of CsPb2Br5 nanoplatelets will be advantageous in future applications of optoelectronic devices. 相似文献
995.
We have prepared ZnSe (luminescent grade) phosphor doped with Sn and (Sn,Pr) with varying concentration in an inert atmosphere in a silica tubular furnace at temperature of (780 ± 20) °C for 1 hr to obtain ZnSe:Sn and ZnSe: (Sn,Pr) phosphors. The photo luminescence (PL) and electroluminescence (EL) spectra of these phosphors have been studied at room temperature and results were discussed in the light of existing models. Dependence of EL emission on the voltage frequency has also been carried out. It is found that the plot between the integrated light intensity versus 1/√Vrms is a straight line suggesting the existence of Mott–Schottky type barrier on the metal semiconductor interface. 相似文献
996.
Meiying Leng Zhengwu Chen Ying Yang Dr. Zha Li Kai Zeng Kanghua Li Dr. Guangda Niu Yisu He Qingchao Zhou Prof. Jiang Tang 《Angewandte Chemie (International ed. in English)》2016,55(48):15012-15016
Lead halide perovskite quantum dots (QDs) are promising candidates for future lighting applications, due to their high quantum yield, narrow full width at half maximum (FWHM), and wide color gamut. However, the toxicity of lead represents a potential obstacle to their utilization. Although tin(II) has been used to replace lead in films and QDs, the high intrinsic defect density and oxidation vulnerability typically leads to unsatisfactory material properties. Bismuth, with much lower toxicity than lead, is promising to constitute lead‐free perovskite materials because Bi3+ is isoelectronic to Pb2+ and more stable than Sn2+. Herein we report, for the first time, the synthesis and optical characterization of MA3Bi2Br9 perovskite QDs with photoluminescence quantum yield (PLQY) up to 12 %, which is much higher than Sn‐based perovskite nanocrystals. Furthermore, the photoluminescence (PL) peaks of MA3Bi2X9 QDs could be easily tuned from 360 to 540 nm through anion exchange. 相似文献
997.
Understanding the Photoluminescence Mechanism of Nitrogen‐Doped Carbon Dots by Selective Interaction with Copper Ions 下载免费PDF全文
Doped fluorescent carbon dots (CDs) have drawn widespread attention because of their diverse applications and attractive properties. The present report focusses on the origin of photoluminescence in nitrogen‐doped CDs (NCDs), which is unraveled by the interaction with Cu2+ ions. Detailed spectroscopic and microscopic studies reveal that the broad steady‐state photoluminescence emission of the NCDs originates from the direct recombination of excitons (high energy) and the involvement of defect states (low energy). In addition, highly selective detection of Cu2+ is achieved, with a detection limit of 10 μm and a dynamic range of 10 μm –0.4 mm . The feasibility of the present sensor for the detection of Cu2+ in real water samples is also presented. 相似文献
998.
Zinc sulfide (ZnS) thin films have been successfully deposited via spray pyrolysis using an aqueous solution of thiourea and zinc acetate onto glass substrate. The effect of varying substrate temperature (150, 200,250 and 300 °C) on structure and optical properties is presented. The films have been characterized by X- ray diffraction (XRD), UV-Vis-NIR spectrometry, photoluminescence (PL) spectroscopy and field emission scanning electron microscopy (FESEM). All the deposited ZnS films exhibit a cubic structure, while crystallinity and morphology are found to depend on spray temperature. PL analysis indicates the presence of violet and green emissions arising from Zn and S vacancies. The value of bandgap of ZnS films is found to decrease slightly with increasing substrate temperature; varying in the range 3.52–3.25 eV, most probably associated with the formation of Zn(S,O) solid solution. 相似文献
999.
Cigdem Hopa Ismail Cokay 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(8):601-606
Schiff bases are considered `versatile ligands' in coordination chemistry. The design of polynuclear complexes has become of interest due to their facile preparations and varied synthetic, structural and magnetic properties. The reaction of the `ligand complex' [CuL] {H2L is 2,2′‐[propane‐1,3‐diylbis(nitrilomethanylylidene)]diphenol} with Ni(OAc)2·4H2O (OAc is acetate) in the presence of dicyanamide (dca) leads to the formation of bis(dicyanamido‐1κN1)bis(dimethyl sulfoxide)‐2κO,3κO‐bis{μ‐2,2′‐[propane‐1,3‐diylbis(nitrilomethanylylidene)]diphenolato}‐1:2κ6O,O′:O,N,N′,O′;1:3κ6O,O′:O,N,N′,O′‐dicopper(II)nickel(II), [Cu2Ni(C17H16N2O2)2(C2N3)2(C2H6OS)2]. The complex shows strong absorption bands in the frequency region 2155–2269 cm−1, which clearly proves the presence of terminal bonding dca groups. A single‐crystal X‐ray study revealed that two [CuL] units coordinate to an NiII atom through the phenolate O atoms, with double phenolate bridges between CuII and NiII atoms. Two terminal dca groups complete the distorted octahedral geometry around the central NiII atom. According to differential thermal analysis–thermogravimetric analysis (DTA–TGA), the title complex is stable up to 423 K and thermal decomposition starts with the release of two coordinated dimethyl sulfoxide molecules. Free H2L exhibits photoluminescence properties originating from intraligand (π–π*) transitions and fluorescence quenching is observed on complexation of H2L with CuII. 相似文献
1000.
Silicon Nanocrystals and Silicon‐Polymer Hybrids: Synthesis,Surface Engineering,and Applications 下载免费PDF全文
Dr. Mita Dasog Julian Kehrle Prof. Dr. Bernhard Rieger Prof. Dr. Jonathan G. C. Veinot 《Angewandte Chemie (International ed. in English)》2016,55(7):2322-2339
Silicon nanocrystals (Si‐NCs) are emerging as an attractive class of quantum dots owing to the natural abundance of silicon in the Earth's crust, their low toxicity compared to many Group II–VI and III–V based quantum dots, compatibility with the existing semiconductor industry infrastructure, and their unique optoelectronic properties. Despite these favorable qualities, Si‐NCs have not received the same attention as Group II–VI and III–V quantum dots, because of their lower emission quantum yields, difficulties associated with synthesizing monodisperse particles, and oxidative instability. Recent advancements indicate the surface chemistry of Si‐NCs plays a key role in determining many of their properties. This Review summarizes new reports related to engineering Si‐NC surfaces, synthesis of Si‐NC/polymer hybrids, and their applications in sensing, diodes, catalysis, and batteries. 相似文献