Kvistloomis4184

High-performance solar cells demand efficient charge-carrier excitation, separation, and extraction. These requirements hold particularly true for molecular photovoltaics, where large exciton binding energies render charge separation challenging at their commonly complex donor-acceptor interface structure. Among others, charge-transfer (CT) states are considered to be important precursors for exciton dissociation and charge separation. However, the general nature of CT excitons and their formation pathways remain unclear. Layered quasiplanar crystalline molecular heterostructures of the prototypical donor-acceptor system pentacene-perfluoropentacene studied at cryogenic temperatures are a paramount model system to gain insights into the underlying physical mechanism. In particular, a detailed experiment-theory analysis on a layered heterojunction featuring perfluoropentacene in its π-stacked polymorph and pentacene in the Siegrist phase indicates that exciton diffusion in unitary films can influence the formation efficiency of CT excitons localized at internal interfaces for these conditions. The correlation of the structural characteristics, that is, the molecular arrangement at the interfaces, with their absorption and photoluminescence excitation spectra is consistent with exciton transfer from pentacene to the CT exciton state only, whereas no transfer of excitons from the perfluoropentacene is detected. Electronic structure calculations of the model systems and investigation of coupling matrix elements between the various electronic states involved suggest hampered exciton diffusion toward the internal interface in the perfluoropentacene films. GSK1838705A supplier The asymmetric energy landscape around an idealized internal donor-acceptor interface thus is identified as a reason for asymmetric energy transfer. Thus, long-range effects apparently can influence charge separation in crystalline molecular heterostructures, similar to band gap bowing, which is well established for inorganic pn-junctions.Two-dimensional (2D) hybrid perovskites of Ruddlesden-Popper (RP) lattices are recently booming as a vigorous class of ferroelectrics, whereas their intrinsic van der Waals gaps exert weak interactions that destabilize the layered motifs. Thus, it is an urgent challenge to reduce interlayered energy gaps to allow an exploration of stable RP ferroelectrics. Here, we propose hydrogen bonds to reduce van der Waals gaps of 2D RP-type perovskites while the ferroelectricity is retained. For the first time, a homoconformational trans isomer has been alloyed as the spacing cation of the 2D ferroelectric (t-ACH)2(EA)2Pb3Br10 (1, where t-ACH is 4-aminomethyl-1-cyclohexanecarboxylate and EA is ethylammonium). Strikingly, the strong O-H···O hydrogen bonds link adjacent spacing sheets to build a quasi-RP motif with a lower energy gap. In terms of ferroelectricity, the mixed-cation alloying has a crucial role in spontaneous polarization (Ps), as verified by structure analyses, quadratic optical nonlinearity, and electric hysteresis loops. The ordering of t-ACH+ and EA+ cations induces mmmFm symmetry breaking, along with an unusual in-plane Ps value of ∼2.9 μC/cm2 in the ac plane. In combination with the anisotropic nature of its 2D motif, this ferroelectricity creates strong linearly polarized light sensitivity with a large dichroism ratio of ∼3.2, far beyond those of most of the inorganic 2D systems. As far as we know, a 2D RP-type ferroelectric with a trans isomer cationic spacer is unprecedented, and the concept of reducing energy gaps via H-bonding interactions will strengthen the layered perovskite structure and shed light on the rational design of stable ferroelectrics toward photoelectric applications.Traditional harsh chemical cleaning-in-place (CIP) is corrosive to membranes but has limited inhibition on refouling, a tough problem for long-term operation of reverse osmosis (RO). Mild enzymatic cleaning (at pH 9) is a promising alternative but lacks long-term verification and insightful elucidation. In this study, we investigated the instantaneous efficiency, postcleaning refouling, and biological effect of enzymatic CIP (compounded with lipase, protease, and sodium dodecyl sulfate) on practical RO membranes during a 500 h multicycle operation. The enzymatic CIP had an average cleaning efficiency of 77%, which is comparable to a commercial harsh CIP benchmark (pH > 12). It mitigated refouling by shaping the biofilm into a loose and porous architecture where newly arrived organics conformed standard blocking, whereas harsh chemicals rendered a smooth and dense gel layer with quick refouling in intermediate blocking or cake filtration mode. Such structural disparities were dominated by polysaccharides according to quantitative chemical analyses. Gene sequencing and ecological network analysis further proved that the behavior of polysaccharide-related keystone species (such as Sphingomonas and Xanthomonas) significantly changed after long-term enzymatic treatment. In this regard, the mild selective pressure of enzymatic reagents can directionally regulate microbial dynamics, alter foulant layer structure via bio-organic synchronicity, mitigate refouling, and eventually improve the sustainability of RO operation.In this paper, we present a copper(I)-catalyzed nitrile-addition/N-arylation ring-closure cascade for the synthesis of 5,11-dihydro-6H-indolo[3,2-c]quinolin-6-ones from 2-(2-bromophenyl)-N-(2-cyanophenyl)acetamides. Using CuBr and t-BuONa in dimethylformamide (DMF) as the optimal reaction conditions, the cascade reaction gave the target products, in high yields, with a good substrate scope. Application of the cascade reaction was demonstrated on the concise total syntheses of alkaloid isocryptolepine. Further optimization of the products from the cascade reaction led to 3-chloro-5,12-bis[2-(dimethylamino)ethyl]-5,12-dihydro-6H-[1,3]dioxolo[4',5'5,6]indolo[3,2-c]quinolin-6-one (2k), which exhibited the characteristic DNA topoisomerase-I inhibitory mechanism of action with potent in vitro anticancer activity. Compound 2k actively inhibited ARC-111- and SN-38-resistant HCT-116 cells and showed in vivo activity in mice bearing human HCT-116 and SJCRH30 xenografts. The interaction of 2k with the Top-DNA cleavable complex was revealed by docking simulations to guide the future optimization of 5,11-dihydro-6H-indolo[3,2-c]quinolin-6-ones as topoisomerase-I inhibitors.Fluoroarenes are widely used in medicinal, agricultural, and materials chemistry, and yet their production remains a critical challenge in organic synthesis. Indeed, the nearly identical physical properties of these vital building blocks hinders their purification by traditional methods, such as flash chromatography or distillation. As a result, the Balz-Schiemann reaction is currently employed to prepare fluoroarenes instead of more atom-economical C-H fluorination reactions, which produce inseparable mixtures of regioisomers. Herein, we propose an alternative solution to this problem the purification of mixtures of fluoroarenes using metal-organic frameworks (MOFs). Specifically, we demonstrate that controlling the interaction of fluoroarenes with adjacent coordinatively unsaturated Mg2+ centers within a MOF enables the separation of fluoroarene mixtures with unparalleled selectivities. Liquid-phase multicomponent equilibrium adsorption data and breakthrough measurements coupled with van der Waals-corrected density functional theory calculations reveal that the materials Mg2(dobdc) (dobdc4- = 2,5-dioxidobenzene-1,4-dicarboxylate) and Mg2(m-dobdc) (m-dobdc4- = 2,4-dioxidobenzene-1,5-dicarboxylate) are capable of separating the difluorobenzene isomers from one another. Additionally, these frameworks facilitate the separations of fluoroanisoles, fluorotoluenes, and fluorochlorobenzenes. In addition to enabling currently unfeasible separations for the production of fluoroarenes, our results suggest that carefully controlling the interaction of isomers with not one but two strong binding sites within a MOF provides a general strategy for achieving challenging liquid-phase separations.Natural piperine from black pepper is known to function as hypocholesterolemic agent, but how it lowers the blood cholesterol remains unclear. In this study, we found that intragastric administrations of piperine (25 mg/kg/day) for 8 weeks significantly reduced the plasma triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) in high-fat diet (HFD)-fed mice. H&E staining indicated that piperine significantly decreased hepatic lipid accumulation compared with the control group. The Oil Red O staining further showed that piperine attenuated lipid deposition in liver HepG2 cells in a concentration-dependent manner. Mechanistically, piperine treatment caused a significant upregulation of hepatic scavenger receptor B1 (SR-B1) in the liver and transporter protein of ATP binding cassette SGM8 (ABCG8) in the small intestine. Taken together, our findings demonstrate the role of natural piperine in improving lipid metabolic profile that is involved in the reverse cholesterol transport (RCT)-mediated mechanism through upregulation of SR-B1 in the liver and ABCG8 in the small intestine.Dynamic control of engineered microbes using light via optogenetics has been demonstrated as an effective strategy for improving the yield of biofuels, chemicals, and other products. An advantage of using light to manipulate microbial metabolism is the relative simplicity of interfacing biological and computer systems, thereby enabling in silico control of the microbe. Using this strategy for control and optimization of product yield requires an understanding of how the microbe responds in real-time to the light inputs. Toward this end, we present mechanistic models of a set of yeast optogenetic circuits. We show how these models can predict short- and long-time response to varying light inputs and how they are amenable to use with model predictive control (the industry standard among advanced control algorithms). These models reveal dynamics characterized by time-scale separation of different circuit components that affect the steady and transient levels of the protein under control of the circuit. Ultimately, this work will help enable real-time control and optimization tools for improving yield and consistency in the production of biofuels and chemicals using microbial fermentations.A grid-based principal component analysis method (GBPCA) has been developed and implemented to investigate the modes of collective molecules present in the cube in the grid system from their trajectories using molecular dynamics (MD) simulation. This method is applied to the simulations of water, methane, and hydrated proteins. In the cases of single molecules, GBPCA demonstrates that while individual molecules interact with other molecules and move randomly, the collective molecules nevertheless produce cooperative principal component (PC) modes. Notably, these PC modes of the collective molecules formed vorticial or symmetrical structures, with some resembling torus-like structures. Such structures were observed not only in simulations with models that reproduced real molecules, such as water or methane, but also in simulations with artificial molecules that were modified to interact weakly or only repulsively. On the contrary, molecules without any interactions did not exhibit the cooperative PC modes that lead to the formation of specific structures.