The cocrystallization behavior of poly(3-alkylthiophene)s (P3ATs) of varying regioregularity and alkyl chain length was explored via differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) studies. For the regioregular samples both DSC and WAXS studies revealed that cocrystallization was limited to the difference of the alkyl chain length by two carbon atoms. On the other hand, P3AT samples with the same alkyl chain length but different regioregularities cocrystallized with a difference of 17 mol % head to tail (H-T) regularity studied here. P3AT samples with varying regioregularity and alkyl chain length by two carbon atoms showed cocrystallization for a regioregularity difference of 7 mol %. The WAXS study indicated that cocrystals had crystallized within the same interchain lamella and noncocrystals had crystallized within the independent interchain lamella of the components. It also indicated the formation of type 1 P3AT crystals with a noninterdigited side chain during the cocrystallization by melt-quenched conditions for all the samples. The phase diagrams clearly revealed that in some systems at the lower melting component rich region there exist two phase regions. The conductivity of the cocrystals, in both the doped and undoped states, is either intermediate or lower than the line joining their component conductivity values.
In gold nanoparticles (Au NPs) capped with dodecanethiol (DT), the authors report the observation of superparamagnetic blocking temperature TB≃50K in D≃5nm NPs but only diamagnetism in 12nm NPs. For T<TB=50K, the strong temperature dependence of coercivity Hc, saturation magnetization Ms, and exchange bias He (in the field-cooled sample) confirm the blocked state resembling ferromagnetism with Hc≃250Oe, He≃−40Oe, and Ms≃10−2emu∕g at 5K. The observed electron magnetic resonance line shows expected shift, broadening, and reduced intensity below TB. A magnetic moment μ≃0.006μB per Au atom attached to DT is determined using a model which yields Ms varying as 1∕D, with its source being holes in the 5d band of Au produced by charge transfer from Au to S atoms in DT.
Camptothecin (CPT), a natural product and its synthetic derivatives exert potent anticancer activity by selectively targeting DNA Topoisomerase I (Top1) enzyme. CPT and its clinically approved derivatives are used as Top1 poisons for cancer therapy suffer from many limitations related to stability and toxicity. In order to envisage structurally diverse novel chemical entity as Top1 poison with better efficacy, Ligand-based-pharmacophore model was developed using 3D QSAR pharmacophore generation ( HypoGen algorithm) methodology in Discovery studio 4.1 clients. The chemical features of 29 CPT derivatives were taken as the training set. The selected pharmacophore model Hypo1 was further validated by 33 test set molecules and used as a query model for further screening of 1,087,724 drug-like molecules from ZINC databases. These molecules were subjected to several assessments such as Lipinski rule of 5, SMART filtration and activity filtration. The molecule obtained after filtration was further scrutinized by molecular docking analysis on the active site of Top1 crystal structure (PDB ID: 1T8I ). Six potential inhibitory molecules have been selected by analyzing the binding interaction and Ligand-Pharmacophore mapping with the validated pharmacophore model. Toxicity assessment TOPKAT program provided three potential inhibitory ‘hit molecules’ ZINC68997780, ZINC15018994 and ZINC38550809. MD simulation of these three molecules proved that the ligand binding into the protein-DNA cleavage complex is stable and the protein-ligands conformation remains unchanged. These three hit molecules can be utilized for designing future class of potential topoisomerase I inhibitor.
Dexterity in the application of defect engineering implicates modification in the physical properties of two-dimensional (2D) transition metal dichalcogenides (TMDs) to enhance their effectiveness toward nanoelectronics applications. Subsequently, the existence of various types of defects in monolayer MoS2 has been employed to inculcate and implement their significance in enhancing the Li/Na-ion storage capability of MoS2 monolayers as anodes of lithium ion batteries (LIBs) and sodium ion batteries (SIBs). DFT calculations have guided us to traverse the effect of various point and antisite defects on Li/Na adsorption energy and the diffusion barrier of monolayer MoS2. Before looking into Li/Na adsorption properties of defective MoS2, the structural stability of various defects is explored with relevance to their formation energy. This also germinates the quest for the most stable defective structures that could be a reliable anode material for LIBs and SIBs. Enhanced adsorption is found for both Li/Na ions in the case of defective MoS2 over that corresponding to pristine MoS2. To study the level of interaction between Li/Na and defective MoS2, electronic structure analysis has been performed. To evaluate the possible migration pathways and rate of migration of Li/Na over defective MoS2, we calculated the diffusion barrier energy through the CI-NEB method. Our study demonstrates that the formation of vacancy improves the diffusion performance of both lithium and sodium at the defective region which are prerequisites for LIBs and SIBs. Additionally, we demonstrated that the formation of vacancy could improve the specific capacity of monolayer MoS2 due to a decrease of the molecular mass of defective MoS2 in comparison to pristine MoS2. However, the OCV is not affected much due to enhanced adsorption. Hence, designing MoS2 nanostructures with defects is a useful strategy to achieve an effective anode material for obtaining high capacity LIBs and SIBs by precisely tailoring its properties for desired applications, such as enhancing the adsorption energy, modulating the reaction pathway, and raising the specific capacity.
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