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971.
We have demonstrated a speckle reduction method using motionless image conduits (MICs). Different experimental conditions by introducing the high-coherence HeNe laser and the low-coherence laser diode (LD) as the illumination light sources, by employing the straight MIC and the curved MIC as the speckle reduction components, and by recording speckle images without (objective speckle) and with (subjective speckle) the imaging lens mounted on the CCD camera are conducted, respectively. The most efficient speckle reduction condition is found by the combination of using the LD and the curved MIC, where the objective speckle contrast ratio is reduced from 0.7378 to 0.1725. Experimental results are discussed, and the causes for these speckle reduction efficiency changes are given. 相似文献
972.
Dr. Sourav Maiti Dr. Jayanta Dana Prof. Dr. Hirendra N. Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(3):692-702
The photovoltaic performance of quantum-dot solar cells strongly depends on the charge-carrier relaxation and recombination processes, which need to be modulated in a favorable way to obtain maximum efficiency. Recently, significant efforts have been devoted to investigate the carrier dynamics of nanocrystal sensitizers, both in solution and deposited on TiO2 photoanodes, with the aim to correlate the excitonics with solar-energy conversion efficiency. This Minireview summarizes some proof of the concepts that efficiency can be directly correlated to the exciton dynamics of quantum-dot solar cells. The presented findings are based on CdSeS alloy, CdSe/CdS core/shell, Au/CdSe nanohybrids, and Mn-doped CdZnSSe nanocrystals, where the favourable excitonic processes are optimized to enhance the efficiency. Future prospects and limitations are addressed as well. 相似文献
973.
974.
Dr. Rianne M. Lord Dr. Markus Zegke Imogen R. Henderson Dr. Christopher M. Pask Dr. Helena J. Shepherd Prof. Patrick C. McGowan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):495-500
This report presents a new library of organometallic iridium(III) compounds of the type [Cp*IrCl(L)] (Cp*=pentamethylcyclopentadienyl and L=a functionalized β-ketoiminato ligand) showing moderate to high cytotoxicity against a range of cancer cell lines. All compounds show increased activity towards colorectal cancer, with preferential activity observed against the immortalized p53-null colorectal cell line, HCT116 p53-/-, with sensitivity factors (SF) up to 26.7. Additionally, the compounds have excellent selectivity for cancerous cells when tested against normal cell types, with selectivity ratios (SR) up to 35.6, contrary to that of cisplatin, which is neither selective nor specific for cancerous cells (SF=0.43 and SR=0.7–2.3). This work provides a preliminary understanding of the cytotoxicity of iridium compounds in the absence of p53 and has potential applications in treatment of cancers for which the p53 gene is absent or mutant. 相似文献
975.
Akshat M. Desai Dr. Prabhat K. Singh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(8):2035-2042
Devising sensors for the perrhenate anion in aqueous media is extremely challenging, and has seldom been reported in the literature. Herein, we report a fluorescence turn-on sensor for the perrhenate anion in aqueous media based on the aggregation-induced emission of a popular ultrafast molecular rotor dye, Thioflavin-T. The selective response towards the perrhenate anion has been rationalized in terms of matching water affinity, with the weakly hydrated perrhenate anion spontaneously forming a contact ion pair with the weakly hydrated ultrafast molecule-rotor-based organic cation, Thioflavin-T, which in turn leads to an aggregate assembly that provides a fluorescence turn-on response towards perrhenate. The sensing response of Thioflavin-T has been found to be quite selective towards the perrhenate anion when tested against anions that are ubiquitously present in the environment, such as chloride, nitrate, and sulfate anions. The formation of self-assembled Thioflavin-T aggregates has also been investigated by time-resolved emission and temperature-dependent measurements. 相似文献
976.
Kellie R. England Dr. Sang Ho Lim Lucy M. C. Luong Prof. Marilyn M. Olmstead Prof. Alan L. Balch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(3):874-878
The mono- and di-chloroform solvates of [Au2(μ-1,2-bis(diphenylarsino)ethane)2](AsF6)2 undergo single-crystal-to-single-crystal transformations that result in gain (over 12 hours) or slow loss (over five years) of only one chloroform molecule. The change in solvation results in changes in the structure and luminescence of the digold cation. The cation consists of a pair of slightly bent As-Au-As units that are connected through the two bridging dpae ligands and by aurophilic interactions with Au⋅⋅⋅Au contacts of 3.05152(15) Å in the disolvate or 2.9570(5) Å in the monosolvate. 相似文献
977.
978.
Dr. Michel Holler Dr. Béatrice Delavaux-Nicot Dr. Jean-François Nierengarten 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(18):4543-4550
Heteroleptic copper(I) complexes combining phenanthroline derivatives (NN) and chelating bisphosphine ligands (PP) are an important class of luminescent materials for various applications. Although thermodynamically stable, [Cu(NN)(PP)]+ derivatives are also kinetically unstable. As a result, a dynamic ligand-exchange reaction is often observed in solution, leading to a dynamic mixture of heteroleptic and homoleptic complexes. To prevent the formation of the homoleptic species, macrocyclic phenanthroline ligands have been used for the preparation of [Cu(NN)(PP)]+ pseudorotaxanes. The topological constraint resulting from the macrocyclic structure of the NN ligand drives the thermodynamic equilibrium towards the exclusive formation of the heteroleptic complex as long as the macrocycle is large and flexible enough to allow for the threading of the PP ligand. Conversely, when the threading is prevented by steric constraints, unprecedented copper(I) complexes with a trigonal coordination geometry are obtained. These results are summarized in the present concept article. 相似文献
979.
Prof. Dr. Shaodong Zhou Dr. Xiaoyan Sun Dr. Lei Yue Dr. Maria Schlangen Prof. Dr. Helmut Schwarz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):2967-2971
The thermal gas-phase reactions of [Al2VO5]+ and [AlV2O6]+ with methane have been explored by using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry complemented by high-level quantum chemical calculations. Both cluster ions chemisorbed methane as the major reaction channels at room temperature. [Al2VO5]+ could break only one C−H bond to liberate CH3, whereas [AlV2O6]+ exhibited higher oxidizing ability such that it brings about the selective generation of formaldehyde. Mechanistic aspects are revealed and the crucial roles of the metal centers are discussed. 相似文献
980.
Arthur H. G. David Pablo García-Cerezo Dr. Araceli G. Campaña Prof. Francisco Santoyo-González Dr. Victor Blanco 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(24):6170-6179
We report the application of the click Michael-type addition reaction to vinyl sulfone or vinyl sulfonate groups in the synthesis of rotaxanes through the threading-and-capping method. This methodology has proven to be efficient and versatile as it allowed the preparation of rotaxanes using template approaches based on different noncovalent interactions (i.e., donor-acceptor π–π interactions or hydrogen bonding) in yields of generally 60–80 % and up to 91 % aided by the mild conditions required (room temperature or 0 °C and a mild base such as Et3N or 4-(N,N-dimethylamino)pyridine (DMAP)). Furthermore, the use of vinyl sulfonate moieties, which are suitable motifs for coupling-and-decoupling (CAD) chemistry, implies another advantage because it allows the controlled chemical disassembly of the rotaxanes into their components through nucleophilic substitution of the sulfonates resulting from the capping step with a thiol under mild conditions (Cs2CO3 and room temperature). 相似文献