The time-dependent density functional theory approach, implemented at hybrid-B3LYP, GGA-PBE, and density functional-based tight binding levels of theory, was used to model photoinjection in organic dye/TiO2 quantum dot to explore the prospects of improvement of dye-sensitized solar cell (DSSC). The photosensitizer used in this study consisted of six carbazole-based organic dyes, a cyanoacrylic acid group as an acceptor and an oligothiophene π-bridge spacer. The modifications were made in the dyes by increasing the length of the spacer by adding thiophene and oxadiazole rings at different positions of the donor-acceptor bridge. The structural variations appeared to alter the electronic and optical properties of dyes studied via energy levels and excitation spectra. The UV-Vis spectra calculated for all the dyes in solvents exhibited a red shift in spectral peaks with an increase in the polarity of the solvents. The findings of the study pointed toward the indirect photoinjection of the dye-(TiO2)96 complex for six different dyes. The substitution of the oxadiazole ring at the center and addition of a thiophene ring at the edge of the spacer produced two dyes that exhibited the lowest injection energies of 0.11 and 0.17 eV, along with the regeneration energies of 1.18 and 1.12 eV, respectively. The dyes reported here may have promising applications in photoanode for enhancing the performance of DSSC. 相似文献
An organic–inorganic hybrid compound Na2(HAn)8[H2W12O42]·16H2O (HAn: p-anisidinium, C7H10NO) has been synthesized under soft acidic conditions and characterized by infrared and UV–visible spectroscopies, thermogravimetric analysis, cyclic voltammetry and single crystal X-ray diffraction. The compound crystallizes in the monoclinic P21/n space group with a = 10.1920(4) Å, b = 34.2901(9) Å, c = 14.0745(5) Å, β = 95.830(3)°, V = 4,893.4(3) Å3 and Z = 4. The compound exhibits a 2D supramolecular structure formed by alternated [paradodecatungstate/Na] and p-anisidinium layers. The catalytic activity of the compound for oxidation of cyclooctene with H2O2 was proved and gives rise to good reaction yield. 相似文献
Monocyclometalated compound [Rh2{(C8H4S)P(C8H5S)2}(CH3CO2H)2(O2CCH3)3] ( 1 a ) and bis‐cyclometalated compound [Rh2{(C8H4S)P(C8H5S)2}2(CH3CO2H)2(O2CCH3)2] ( 2 a ) have been isolated from the reaction of dirhodium tetraacetate and tris(2‐benzo[b]thienyl)phosphine ( 2 BTP ) using low acidic solutions. By contrast, in pure acetic acid the reaction of Rh2(O2CCH3)4 with 2 BTP and tris(2‐thienyl)phosphine ( 2 TP ), followed by replacement of the axial acetate ligands by chlorides, led to [Rh2{(2‐C8H5 S )P(2‐C8H5S)2}2Cl2(O2CCH3)2] ( 3 b ) and [Rh2{(2‐C4H3 S )P(C4H3S)2}2Cl2(O2CCH3)2] ( 5 b ), respectively. These new dirhodium(II) compounds possess equatorial bridging ligands in a phosphorous–sulfur (P,S) coordination mode. The reversible switching between the P,C and P,S bonding mode of the phosphine has been studied in the monocyclometalated [Rh2{(C4H2S)P(C4H3S)2}(CH3CO2H)2(O2CCH3)3] ( 6 a ), which was selectively transformed into compound [Rh2{(2‐C4H3 S )P(C4H3S)2}(CF3SO3)(CH3CO2H)(O2CCH3)3] ( 7 c ) in triflic acid media. Remarkably, compound 7 c reverts to the starting compound 6 a upon treatment with sodium acetate. Theoretical DFT calculations for both the P,C/P,S rearrangement and the base‐promoted reversion have been performed to explain the experimental findings. Data suggest the P,C/P,S rearrangement occurs by means of a “concerted protonation–demetalation mechanism” followed by η2 coordination of the thienyl ring and subsequent isomerization to the S‐η1‐coordination mode. In the reversion reaction, the base coordinated at the axial position would promote a concerted metalation–deprotonation mechanism. 相似文献
Fukuyama reaction for the synthesis of multifunctional aldehydes, secondary amines and ketones has gained considerable importance in synthetic organic chemistry because of mild reaction conditions. The use of thioesters in both Fukuyama aldehydes and ketones synthesis is highly attractive for organic chemists as they are easily accessible from corresponding carboxylic acids. Fukuyama–Mitsunobu reaction utilizes 2-nitrobenzenesulfonyl (Ns) for the protection/activation/deprotection of primary amines to afford secondary amines in good yields and high enantioselectivities. This review presents recent synthetic developments and applications of Fukuyama reaction for the synthesis of aldehydes, secondary amines and ketones.
Crystal fiber of cubic Yb3+-doped KY3F10 has been grown. Both, mono-doped and concentration gradient fibers were grown by laser-heated pedestal growth (LHPG) method under argon atmosphere. The preparation of feed rod materials under CF4 atmosphere prior to LHPG is efficient to obtain oxygen-free fluorides. Yb3+-doped KY3F10 crystals have excellent spectroscopic properties, weak self-quenching property and can be expected for solid-state laser application. 相似文献
For each n≥1, let {Xj,n}1≤j≤n be a sequence of strictly stationary random variables. In this article, we give some asymptotic weak dependence conditions for the convergence in distribution of the point process $N_{n}=\sum_{j=1}^{n}\delta_{X_{j,n}}For each n≥1, let {Xj,n}1≤j≤n be a sequence of strictly stationary random variables. In this article, we give some asymptotic weak dependence conditions
for the convergence in distribution of the point process
Nn=?j=1ndXj,nN_{n}=\sum_{j=1}^{n}\delta_{X_{j,n}}
to an infinitely divisible point process. From the point process convergence we obtain the convergence in distribution of
the partial sum sequence Sn=∑j=1nXj,n to an infinitely divisible random variable whose Lévy measure is related to the canonical measure of the limiting point process.
As examples, we discuss the case of triangular arrays which possess known (row-wise) dependence structures, like the strong
mixing property, the association, or the dependence structure of a stochastic volatility model. 相似文献
A solvent-free, versatile procedure has been developed for the effective synthesis of tert-butanesulfinylimines of a variety of aldehydes using chiral tert-butanesulfinamides under green, sonochemical conditions. This method utilizes silica supported p-toluenesulfonic acid (pTSA·SiO2) as an efficient, safer and inexpensive catalyst under aerobic conditions. The practicable simplicity, easy preparation of the catalyst from readily available substances, high substrate scope, excellent yields of products in short reaction times and environmentally benign (solvent-free sonochemical) conditions are the exceptional assets of this finding. 相似文献
We prove two results on the rotation number of the skew-product system \({(\omega ,A):(\theta ,y)\in\mathbb T^d\times\mathbb R^2\mapsto (\theta +\omega ,A(\theta)y)\in\mathbb T^d\times\mathbb R^2,}\) where ω is Diophantine and \({A(\theta)\in SL(2, \mathbb R)}\) is homotopic to the identity. On the one hand, we prove that this function has the behavior of a \({\frac{1}{2}-}\) Hölder function. On the other, we show that the length of the gaps has a sub-exponential estimate which depends on its label given by the gap-labeling theorem. We give also an estimate of the complement of the spectrum. These results are obtained by studying the reducibility of the quasi-periodic co-cycle (ω , A). 相似文献