Two hetero‐bimetallic Zn(II)2M(II) (M = Ca and Sr) complexes Zn2Ca(L)(OAc)2 (1) and Zn2Sr(L)(OAc)2 (2) with a novel asymmetrical bis(salamo)‐type tetraoxime ligand (H5L) were designed and ...synthesized, and characterized by elemental analyses, FT‐IR spectra, UV–vis absorption spectra, Density Functional Theory (DFT) calculation, Hirshfeld surface analyses and X‐ray single crystal diffractions. Compared with the symmetric bis(salamo)‐type ligands, the ligand H5L and its Zn(II)2M(II) (M = Ca and Sr) asymmetrical bis(salamo)‐type complexes synthesized for the first time in this paper have more novel structures and better properties. The results of ultraviolet titration show that the coordination ratio of ligand, alkaline earth metal and transition metal is 1:1:2. Complexes 1 and 2 have good luminescent properties and obvious antimicrobial activities.
Two hetero‐trinuclear Zn(II)2M(II) (M = Ca and Sr) bis(salamo)‐type complexes Zn2Ca(L)(OAc)2 (1) and Zn2Sr(L)(OAc)2 (2) were designed and synthesized, and characterized structurally. The coordination ratio and structure of the complexes were further determined by ultraviolet titration experiments. The results show that the coordination ratio of transition metal, alkaline earth metal and ligand is 2:1:1. The complexes have good properties, such as good luminescent properties and obvious antimicrobial activities.
The exploration of chiral crystalline porous materials, such as metal-organic complexes (MOCs) or metal-organic frameworks (MOFs), has been one of the most exciting recent developments in materials ...science owing to their widespread applications in enantiospecific processes. However, achieving specific tight-affinity binding and remarkable enantioselectivity toward important biomolecules is still challenging. Perhaps most critically, the lack of adaptability, compatibility, and processability in these materials severely impedes practical applications in chemical engineering and biological technology. In this Perspective, artificial metal-peptide assemblies (MPAs), which are achieved by the assembly of peptides and metals with nanometer-sized cavities or pores, is a new development that could address the current bottlenecks of chiral porous materials. Bioinspired assembly of pore-forming MPAs is not foreign to biological systems and has granted scientists an unprecedented level of control over the chiral recognition sites, conformational flexibility, cavity sizes, and hydrophilic segments through ultrafine-tuning of peptide-derived linkers. We will specifically discuss exemplary MPAs including structurally well-defined metal-peptide complexes and highly crystalline metal-peptide frameworks. With insights from these structures, the peptide assembly and folding by the closer cooperation of metal coordination and noncovalent interactions can create adaptable protein-like nanocavities undergoing a myriad of conformational variations that is reminiscent of enzymatic pockets. We also consider challenges to advancing the field, where the deployment of side-chain groups and manipulation of amino acid sequences are more likely to access the programmable, genetically encodable peptide-mediated porous materials, thus contributing to the enhanced enantioselective recognition as well as enabling key biochemical processes in next-generation versatile biomimetic materials.
Abstract
Estrogens signal through both nuclear and membrane receptors with most reported effects being mediated via the nuclear estrogen receptors (nERs). Although much work has been reported on nERs ...in the zebrafish, there is a lack of direct genetic evidence for their functional roles and importance in reproduction. To address this issue, we undertook this study to disrupt all three nERs in the zebrafish, namely esr1 (ERα), esr2a (ERβII), and esr2b (ERβI), by the genome-editing technology clustered regularly interspaced short palindromic repeats and its associated nuclease (CRISPR/Cas9). Using this loss-of-function genetic approach, we successfully created three mutant zebrafish lines with each nER knocked out. In addition, we also generated all possible double and triple knockouts of the three nERs. The phenotypes of these mutants in reproduction were analyzed in all single, double, and triple nER knockouts in both females and males. Surprisingly, all three single nER mutant fish lines display normal reproductive development and function in both females and males, suggesting functional redundancy among these nERs. Further analysis of double and triple knockouts showed that nERs, especially Esr2a and Esr2b, were essential for female reproduction, and loss of these two nERs led to an arrest of folliculogenesis at previtellogenic stage II followed by sex reversal from female to male. In addition, the current study also revealed a unique role for Esr2a in follicle cell proliferation and transdifferentiation, follicle growth, and chorion formation. Taken together, this study provides the most comprehensive genetic analysis for differential functions of esr1
, esr2a, and esr2b in fish reproduction.
The nuclear estrogen receptors (nERs)—esr1, esr2a, and esr2b—were deleted in the zebrafish. All mutant fish, including single, double, and triple mutants, were analyzed for phenotypes in reproduction.
Broadening the optical absorption of organic photovoltaic (OPV) materials by enhancing the intramolecular push-pull effect is a general and effective method to improve the power conversion ...efficiencies of OPV cells. However, in terms of the electron acceptors, the most common molecular design strategy of halogenation usually results in down-shifted molecular energy levels, thereby leading to decreased open-circuit voltages in the devices. Herein, we report a chlorinated non-fullerene acceptor, which exhibits an extended optical absorption and meanwhile displays a higher voltage than its fluorinated counterpart in the devices. This unexpected phenomenon can be ascribed to the reduced non-radiative energy loss (0.206 eV). Due to the simultaneously improved short-circuit current density and open-circuit voltage, a high efficiency of 16.5% is achieved. This study demonstrates that finely tuning the OPV materials to reduce the bandgap-voltage offset has great potential for boosting the efficiency.
Supramolecular containers featuring both high catalytic activity and high enantioselectivity represent a design challenge of practical importance. Herein, it is demonstrated that a chiral octahedral ...coordination cage can be constructed by using twelve enantiopure Mn(salen)‐derived dicarboxylic acids as linear linkers and six Zn4‐p‐tert‐butylsulfonylcalix4arene clusters as tetravalent four‐connected vertices. The porous cage features a large hydrophobic cavity (≈3944 Å3) decorated with catalytically active metallosalen species and is shown to be an efficient and recyclable asymmetric catalyst for the oxidative kinetic resolution of racemic secondary alcohols and the epoxidation of olefins with up to >99 % enantiomeric excess. The cage architecture not only prevents intermolecular deactivation and stabilizes the Mn(salen) catalysts but also encapsulates substrates and concentrates reactants in the cavity, resulting in enhanced reactivity and enantioselectivity relative to the free metallosalen catalyst.
A chiral octahedral coordination cage is constructed by using twelve enantiopure Mn(salen)‐derived dicarboxylic acids as linear linkers and six Zn4‐p‐tert‐butylsulfonylcalix4arene clusters as tetravalent four‐connected vertices. The porous cage is an efficient and recyclable asymmetric catalyst for the oxidative kinetic resolution of racemic secondary alcohols and the epoxidation of olefins.
Synthetic control over chirality and function is the crowning achievement for metal-organic frameworks, but the same level of control has not been achieved for covalent organic frameworks (COFs). ...Here we demonstrate chiral COFs (CCOFs) can be crystallized from achiral organic precursors by chiral catalytic induction. A total of nine two-dimensional CCOFs are solvothermally prepared by imine condensations of the C
-symmetric 1,3,5-triformylphloroglucinol (Tp) with diamine or triamine linkers in the presence of catalytic amount of (R)- or (S)-1-phenylethylamine. Homochirality of these CCOFs results from chiral catalyst-induced immobilization of threefold-symmetric tris(N-salicylideneamine) cores with a propeller-like conformation of one single handedness during crystallization. The CCOF-TpTab showed high enantioselectivity toward chiral carbohydrates in fluorescence quenching and, after postsynthetic modification of enaminone groups located in chiral channels with Cu(II) ions, it can also be utilized as a heterogeneous catalyst for the asymmetric Henry reaction of nitroalkane with aldehydes.
The voltage loss, determined by the difference between the optical gap (Eg) and the open‐circuit voltage (VOC), is one of the most important parameters determining the performance of organic solar ...cells (OSCs). However, the variety of different methods used to determine Eg makes it hard to fairly compare voltages losses among different material systems. In this paper, the authors discuss and compare various Eg determination methods and show how they affect the detailed calculation of voltage losses, as well as predictions of the maximum achievable power conversion efficiency. The aim of this paper is to make it possible for the OSC community to compare voltage losses in a consistent and reasonable way. It is found that the voltage losses for strongly absorbed photons in state‐of‐the‐art OSCs are not much less than 0.6 V, which still must be decreased to further enhance efficiency.
Different optical gap determination methods and how these different methods affect the quantification of voltage losses of organic solar cells are discussed. Based on state‐of‐the art voltages losses, a power conversion efficiency of ≈18% can be expected for organic solar cells in the near future.
A novel non‐fullerene acceptor, possessing a very low bandgap of 1.34 eV and a high‐lying lowest unoccupied molecular orbital level of −3.95 eV, is designed and synthesized by introducing ...electron‐donating alkoxy groups to the backbone of a conjugated small molecule. Impressive power conversion efficiencies of 8.4% and 10.7% are obtained for fabricated single and tandem polymer solar cells.
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