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91.
Photoinduced Energy Transfer from Poly(N‐vinylcarbazole) to Tricarbonylchloro‐(2,2′‐bipyridyl)rhenium(I) 下载免费PDF全文
Dr. Engelbert Portenkirchner Dogukan Apaydin Gottfried Aufischer Dr. Marek Havlicek Prof. Matthew White Prof. Markus Clark Scharber Prof. Niyazi Serdar Sariciftci 《Chemphyschem》2014,15(16):3634-3638
This work investigates the photoinduced energy transfer from poly(N‐vinylcarbazole) (PVK), as a donor material, to fac‐(2,2′‐bipyridyl)Re(CO)3Cl, as a catalyst acceptor, for its potential application towards CO2 reduction. Photoluminescence quenching experiments reveal dynamic quenching through resonance energy transfer in solid donor/acceptor mixtures and in solid/liquid systems. The bimolecular reaction rate constant at solution–film interfaces for the elementary reaction of the excited state with the quencher material could be determined as 8.8(±1.4)×1011 L mol?1 s?1 by using Stern–Volmer analysis. This work shows that PVK is an effective and cheap absorber material that can act efficiently as a redox photosensitizer in combination with fac‐(2,2′‐bipyridyl)Re(CO)3Cl as a catalyst acceptor, which might lead to possible applications in photocatalytic CO2 reduction. 相似文献
92.
Esra Şen Dr. Kadem Meral Dr. Serdar Atılgan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):736-745
The work presented herein is devoted to the fabrication of large Stokes shift dyes in both organic and aqueous media by combining dark resonance energy transfer (DRET) and fluorescence resonance energy transfer (FRET) in one donor–acceptor system. In this respect, a series of donor–acceptor architectures of 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) dyes substituted by one, two, or three tetraphenylethene (TPE) luminogens were designed and synthesised. The photophysical properties of these three chromophore systems were studied to provide insight into the nature of donor–acceptor interactions in both THF and aqueous media. Because the generation of emissive TPE donor(s) is strongly polarity dependent, due to its aggregation‐induced emission (AIE) feature, one might expect the formation of appreciable fluorescence emission intensity with a very large pseudo‐Stokes shift in aqueous media when considering FRET process. Interestingly, similar results were also recorded in THF for the chromophore systems, although the TPE fragment(s) of the dyes are non‐emissive. The explanation for this photophysical behaviour lies in the DRET. This is the first report on combining two energy‐transfer processes, namely, FRET and DRET, in one polarity‐sensitive donor–acceptor pair system. The accuracy of the dark‐emissive donor property of the TPE luminogen is also presented for the first time as a new feature for AIE phenomena. 相似文献
93.
Serbest Kerim Değirmencioğlu İsmail Karaböcek Serdar Güner Saadettin 《Transition Metal Chemistry》2001,26(1-2):232-236
A new binucleating ligand incorporating four oxime groups, butane-2,3-dione O-[4-aminooxy-2,3-bis-(2-hydroxyimino-1-methyl-propylideneaminooxymethyl)-but-2-enyl]-dioxime, (H4mto), has been synthesized and its dinuclear cobalt(III), copper(II), and homo- and hetero-tetranuclear copper(II)–manganese(II) complexes have been prepared and characterized by 1H- and 13C-n.m.r., i.r., magnetic moments and mass spectral studies. Elemental analyses, stoichiometric and spectroscopic data indicate that the metal ions in the complexes are coordinated to the oxime nitrogen atoms (C=N) and the data support the proposed structure for H4mto and its complexes. Moreover, dinuclear cobalt(III) and copper(II) complexes of H4mto have a 2:1 metal:ligand ratio. 相似文献
94.
Alberto Montaigne Ramil Gerardo Hernandez-Sosa Thomas Griesser Clemens Simbrunner Thomas Höfler Gregor Trimmel Wolfgang Kern Quan Shen Christian Teichert Günther Schwabegger Helmut Sitter Niyazi Serdar Sariciftci 《Applied Physics A: Materials Science & Processing》2012,107(4):985-993
This work reports on the investigation of the photosensitive polymer poly(diphenyl bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate) (PPNB), which undergoes the photo-Fries rearrangement upon illumination with UV-light, used as interfacial layers in organic electronic devices. Two cases were investigated: the use of a blend of PPNB with poly-vinylcarbazole (PVK) as an interlayer in para-sexiphenyl (PSP) based organic light emitting diodes (OLEDs) and the use of PPNB as gate dielectric layer in organic field effect transistors (OFETs). The photo-Fries rearrangement reaction causes a change of the polymer chemical structure resulting in a change of its physical and chemical properties. The electroluminescence spectra and emission of the PSP OLEDs are not affected when fabricated with a non-UV-illuminated PPNB:PVK blend. However, the electroluminescence is totally quenched in those OLEDs fabricated with UV-illuminated PPNB:PVK blend. Although the dielectric constant of PPNB increases upon UV-treatment, it is demonstrated that those OFETs built with UV-treated PPNB as gate dielectric have lower performance than those OFETs built with non-UV-treated PPNB. Furthermore, the effect of the UV-illumination of PPNB and PPNB:PVK blend on the growth of the small molecules C60 and PSP has been studied by atomic force microscopy. Using photolithography, this kind of photochemistry can be performed to spatially control and tune the optical and electrical performance of organic electronic devices. 相似文献
95.
Reaching a control on the mesoscopic morphology and internal molecular arrangement of cyanine aggregates is an important step for realization of devices with tailor-made optical properties. Despite a wealth of research, understanding of the relationship between molecular organization, excitonic states and dynamics of aggregates is still preliminary. To this end, we have employed polarized absorption spectroscopy to investigate the relationship between internal molecular organization and excitonic states of J-aggregates in 1,1′,3,3′tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine (TTBC) thin films in poly-vinyl alcohol (PVA). Angular dependence of the UV–vis spectra has been measured at 11 different orientations between the electric field polarization and the macroscopic alignment axis. Aggregate spectral response consisted of an asymmetrically split Davydov pair of bands exhibiting opposite polarization: an H-band (505 nm, Lorentzian-like, polarized along the macroscopic film axis) and a J-band (594 nm, one-dimensional J-aggregate like band shape, polarized perpendicular to the macroscopic film axis). The polarized absorption observations were found to be consistent with a herringbone model for which the internal molecular arrangement, the excited state structure and dynamics have recently been detailed by us upon interpretation of isotropic absorption data in ionic aqueous solution. 相似文献
96.
Basu and Basu (Statistica Sinica 8:841–860, 1998) have proposed an empty cell penalty for the minimum power-divergence estimators
which can lead to improvements in the small sample properties of these estimators. In this paper, we study the small and moderate
sample performances of the ordinary and penalized minimum power-divergence estimators in terms of efficiency and robustness
for the log-linear models in two-way contingency tables under the assumptions of multinomial sampling. Calculations made by
enumerating all possible sample combinations show that the penalized estimators are competitive with the ordinary estimators
for the moderate samples and definitely better for the smallest sample considered for both efficiency and robustness under
the considered models. The results also reveal that the bigger the main effects the more need for penalization. 相似文献
97.
Ismail Serdar Bakal Joseph Geunes H. Edwin Romeijn 《Journal of Global Optimization》2008,41(4):633-657
In the majority of classical inventory theory literature, demand arises from exogenous sources upon which the firm has little
or no control. In many practical contexts, however, aggregate demand is comprised of individual demands from a number of distinct
customers or markets. This introduces new dimensions to supply chain planning problems involving the selection of markets
or customers to include in the demand portfolio. We present a nonlinear, combinatorial optimization model to address planning
decisions in both deterministic and stochastic settings, where a firm constructs a demand portfolio from a set of potential
markets having price-sensitive demands. We first consider a pricing strategy that dictates a single price throughout all markets
and provide an efficient algorithm for maximizing total profit. We also analyze the model under a market-specific pricing
policy and describe its optimal solution. An extensive computational study characterizes the effects of key system parameters
on the optimal value of expected profit, and provides some interesting insights on how a given market’s characteristics can
affect optimal pricing decisions in other markets. 相似文献
98.
Derya Gülcemal Milena Masullo Ozgen Alankuş‐Çalışkan Tamer Karayıldırım Serdar G. Şenol Sonia Piacente Erdal Bedir 《Magnetic resonance in chemistry : MRC》2010,48(3):239-243
A new secondary metabolite, pterocephaline, along with the known cantleyoside, 7α‐morroniside, 3β,5α‐tetrahydrodesoxycordifoline lactam, 5S‐5‐carboxyvincoside, sweroside, and loganin have been isolated from the aerial parts of P. pinardii (Dipsacaceae). Moreover, cantleyoside‐methyl‐hemiacetal and cantleyoside‐dimethyl‐acetal were obtained as seco‐iridoid artifacts. The structures were elucidated by extensive spectroscopic methods including 1D‐(1H, 13C and TOCSY) and 2D‐NMR (DQF‐COSY, HSQC and HMBC). Monoterpenoid glucoindole alkaloids were encountered for the first time in Dipsacaceae family. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
99.
M. Serdar Çavu? 《Journal of Non》2011,357(1):202-205
In this paper, we begin introducing some basic definitions and mathematical preliminaries of the fractional calculus theory. By using the fractional calculus technique (that is, calculus of derivatives and integrals of any arbitrary real or complex order) a solution of the fractional master equation derived from the stochastic Ising model of Glauber has been obtained and the result is applied to an analysis of the dielectric relaxation processes. From the solution of the equation, the Cole-Cole dispersion relation, KWW (Kohlrausch-William-Watts) equation and algebraic decay relaxation functions are obtained easily. Then these functions are compared with Bozdemir's earlier analysis of the stochastic Ising model. 相似文献
100.
We report on the determination of choline and acetylcholine via biocentrivoltammetry. This method combines centrifugation and voltammetry and is based on a carbon paste electrode modified with acetylcholinesterase and choline oxidase. The electrode was placed at the bottom of a biocentrivoltammetric cell. Acetylcholine and choline are accumulated on the enzyme electrode via centrifugative forces, upon which a direct voltammetric scan is applied. Reaction time, pH values, quantities of enzyme and centrifugation parameters were optimized. A linear response is obtained in the 0.07 to 10?μM concentration range of acetylcholine, and a limit of detection as low as 0.5?μM. The linear range is between 0.1 and 500?μM for choline. The method was applied to the determination of acetylcholine and choline in spiked serum samples. Figure
This work constitutes the first application of biocentri-voltammetry for ACh detection. Biocentri-voltammetry is the method where centrifuge and voltammetry is combined in a specially designed working cell. As a result, sensitive and effective biosensor was obtained. 相似文献