Herein, we report a copper/amine catalyzed stereoselective addition of alkynes to ketenimine intermediates generated in situ from the sulfonyl azide-alkyne cycloaddition cascade for the stereoselective synthesis of (Z)-1,3-enynes. Significantly, for the first-time, enamine intermediates generated in the copper-catalyzed sulfonyl azide-alkyne cycloaddition reactions have been successfully trapped and isolated as the products. Density functional theory computations have also been performed and found to be consistent with the observed experimental stereoselectivity.
Blends of π-conjugated polymers and fullerene derivatives are ubiquitous as the active layers of organic solar cells. However, a detailed understanding of the weak noncovalent interactions at the molecular level between the polymer chains and fullerenes is still lacking and could help in the design of more efficient photoactive layers. Here, using a combination of long-range corrected density functional theory calculations and molecular dynamic simulations, we report a thorough characterization of the nature of binding between fullerenes (C60 and PC61BM) and poly(benzo[1,2-b:4,5-b′]dithiophene–thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) chains. We illustrate the variations in binding strength when the fullerenes dock on the electron-rich vs electron-poor units of the polymer as well as the importance of the role played by the polymer and fullerene side chains and the orientations of the PC61BM molecules with respect to the polymer backbones.
For the first time, we present the detailed synthesis, photophysical, electrochemical, host-guest and charge transport properties of spiro[fluorene-9,9'-xanthene] (SFX) and carbazole macrocycle SPS-NR-02. The electron and hole transport values measured using the space charge limited current (SCLC) method resulted in ambipolar charge transport with an electron to hole mobility ratio of 0.39.
Abstract Introduction: Despite several in vitro and in vivo applications of low-intensity pulsed ultrasound (LIPUS), it remains an under-studied feature of the oral and maxillofacial region. The goal of this in vivo study was to objectively investigate the efficacy of low-intensity pulsed ultrasound on wound healing and related morbidities following surgical removal of an impacted third molar. Materials and Methods: The following in vivo prospective, comparative, randomised controlled clinical study was carried out amongst 56 patients who reported to the Department of Oral and Maxillofacial Surgery fulfilling the inclusion criteria. Group A received sham ultrasound, whereas Group B received LIPUS therapy. Based on the group allocated LIPUS 1 MHz, pulsed 20% and dose 1.0 watts/square centimetre (W/cm 2 )/sham, ultrasound therapy was given on 1 st , 2 nd and 3 rd post-operative days. The assessment of post-operative pain, oedema, trismus and wound healing on preoperative, first, third and seventh postoperative days. Results: The quantitative variables of the study were assessed using independent sample t -test, and qualitative variables were assessed using the Chi-square test. The P < 0.05 on third and seventh post-op days for pain, trismus and wound healing in the LIPUS group compared to control group making it statistically significant. There was no statistically significant difference in the reduction of oedema amongst the two groups. Discussion: Post-LIPUS application in the patients, postoperative pain was significantly reduced, trismus was noticeably improved and wound healing was satisfactory and can be employed as a complementary technique.
Abstract Organic solar cells that use only fullerenes as the photoactive material exhibit poor exciton‐to‐charge conversion efficiencies, resulting in low internal quantum efficiencies (IQE). However, the IQE can be greatly improved, when copper(I) thiocyanate (CuSCN) is used as a carrier‐selective interlayer between the phenyl‐C70‐butyric acid methyl ester (PC 70 BM) layer and the anode. Efficiencies of ≈5.4% have recently been reported for optimized CuSCN:PC 70 BM (1:3)‐mesostructured heterojunctions, yet the reasons causing the efficiency boost remain unclear. Here, transient absorption (TA) spectroscopy is used to demonstrate that CuSCN does not only act as a carrier‐selective electrode layer, but also facilitates fullerene exciton dissociation and hole transfer at the interface with PC 70 BM. While intrinsic charge generation in neat PC 70 BM films proceeds with low yield, hybrid films exhibit much improved exciton dissociation due to the presence of abundant interfaces. Triplet generation with a rate proportional to the product of singlet and charge concentrations is observed in neat PC 70 BM films, implying a charge–singlet spin exchange mechanism, while in hybrid films, this mechanism is absent and triplet formation is a consequence of nongeminate recombination of free charges. At low carrier concentrations, the fraction of charges outweighs the population of triplets, leading to respectable device efficiencies under one sun illumination.
Abstract In this study, an effort has been made to analyze the aromaticity of oligomers of benzene and thiophene, with and without linkers using Nucleus-Independent Chemical Shift (NICS) as a descriptor, and their relation with HOMO-LUMO gap, reorganization energy and excitation energy. Thus, calculations have been performed to develop structure-aromaticity-spectroscopy relationship. Although the inter-relationship between geometry and aromaticity has been extensively discussed in the literature, the present study provides pointers about relationship between aromaticity, conjugation, and spectroscopic properties. Benzene and thiophene-based oligomers have been chosen for the study comprising of vinyl and ethynyl linkers along with the α-linked benzene and thiophene oligomers as model systems. The results show that both HOMO-LUMO gaps and excitation energies exhibit linear relationship with inverse of the NICS values, indicating the possible existence of the structure-aromaticity-π-conjugation-spectroscopy relationship.
Two regioregular narrow bandgap conjugated polymers with a D′–A–D–A repeat unit architecture were synthesized for PSC applications. Determination of Ect in these solar cells reveals insightful changes in the energy loss relative to similar previously reported chemical structures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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