A Modular and Convergent Synthetic Route to Supramolecular Cyclic Dimers Based on Amidinium‐Carboxylate Interactions

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A Modular and Convergent Synthetic Route to Supramolecular Cyclic Dimers Based on Amidinium-Carboxylate Interactions

A versatile synthetic approach towards supramolecularly programmed monomers that can form discrete macrocyclic species of controllable size and shape through amidinium-carboxylate interactions in both apolar and polar media is described.


Abstract

We describe herein the optimized design and modular synthetic approach towards supramolecularly programmed monomers that can form discrete macrocyclic species of controllable size and shape through amidinium-carboxylate interactions in apolar and polar media.

Multifunctional Self‐Assembled Ionic Liquid Modified Rigid and Flexible Substrates for Efficient Simple‐Structured Perovskite Solar Cells

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Multifunctional Self-Assembled Ionic Liquid Modified Rigid and Flexible Substrates for Efficient Simple-Structured Perovskite Solar Cells

Ionic liquids can do more! A facile and efficient self-assembled [HOEtMIM]Cl layer is introduced for the first time in the rigid and flexible electron transport layer-free perovskite solar cells, giving rise an improved power conversion efficiency of 19.60 % and 15.57 %, along with an improved hysteresis and stability.


Abstract

The advancement of electron transport layer (ETL)-free perovskite solar cells (PSCs) is crucial for the commercialization of PSCs. At present, the slow electron extraction and significant carrier recombination, related to the energy-level alignment at the FTO/perovskite interface, restrict the performance of ETL-free PSCs. The facile modification of bottom electrodes is pivotal for tackling these issues and stimulating the photovoltaic potential of perovskite. Herein, a cost-competitive and neoteric 1-hydroxyethyl-3-methylimidazolium chloride, [HOEtMIM]Cl, ionic liquid is employed to modify the surface of rigid and flexible electrodes, and thus enable an energetically well-aligned interface with perovskite layer via the electric dipole effects. The resulting barrier-free FTO/perovskite contact can tremendously ameliorate the electron extraction and collection, with mitigated nonradiative interfacial carrier recombination loss. Additionally, the lone pair on the nitrogen of the imidazole group passivates the surface defects of perovskite layers, and the chloride anion plays a role in the crystallinity improvement of perovskite. Leveraged by the [HOEtMIM]Cl modification, the resulting ETL-free rigid and flexible devices deliver an outstanding power conversion efficiency of 19.60 % and 15.57 %, along with the ameliorated hysteresis and long-term tenability. This finding highlights the drastic potential of the engineered [HOEtMIM]Cl in manufacturing stable and high-performance ETL-free PSCs for their scaled-up production.

Dimension Tuning of All‐Inorganic Ag‐Based Metal Halides by Solvent Engineering

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Dimension Tuning of All-Inorganic Ag-Based Metal Halides by Solvent Engineering

Herein, different dimensions of Cs2AgCl3 (1D) and CsAgCl2 (2D) metal halides have been synthesized in different solvents, DMF and DMSO, respectively. By comparing the functional group, dielectric constant, and donor number among four solvents (DMF, DMSO, DMAC, DMPU), we find the donor number plays the predominant role in the dimension tuning.


Abstract

Dimension growth of metal halides is important for its properties and applications. However, such dimension control of the metal halides is rarely reported in the literature and the growth mechanism is not clear yet. A minute difference of solvent properties can tremendously alter the process of nucleation and growth of crystals. Herein, an intriguing phenomenon of dimension tuning for Ag-based metal halides is reported. The 1D Cs2AgCl3 crystals can be obtained in pure DMF while the 2D CsAgCl2 crystals are obtained in pure DMSO. Both exhibit bright yellow emission, which are derived from self-trapping excitons (STEs). The photoluminescence quantum yield (PLQY) of Cs2AgCl3 (1D) and CsAgCl2 (2D) are 28.46 % and 20.61 %, respectively. In order to understand the mechanism of the dimension change, additional solvents (N,N-dimethylacetamide, DMAC, 1,3-Dimethyl-Tetrahydropyrimidin-2(1H)-one, DMPU) are also selected to process the precursor for crystal growth. By comparing the functional group, dielectric constant, and donor number among the four solvents, we find the donor number plays the predominant role in nucleation process for Cs2AgCl3 and CsAgCl2. This research reveals the relationship between coordination ability of the solvent and the dimension of metal halides.

Germanium Analogue of the Parent Phosphine−Borane FLP Compound

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Germanium Analogue of the Parent Phosphine−Borane FLP Compound

✓Nucleophilic aromatic substitution by an electron-rich germylone. ✓Synthesis of a Ge analogue of the parent phosphine−borane FLP. ✓Functionalization and interconversion of the formed Ge−B complexes.


Abstract

Diimino−carbene-supported germylone dimNHCGe does not react with BPh3 and does not activate dihydrogen in the FLP mode in the combination with this borane. However, it reacts with B(C6F5)3 to give the zwitterionic borate dimNHCGe−(C6F4)BF(C6F5)2. This compound can be converted into the hydroborate dimNHCGe−(C6F4)BH(C6F5)2 (8) and further into [dimNHCGe−(C6F4)B(C6F5)2]+ (4). Compound 4 is a Ge/B analogue of Stephan's FLP parent P/B compound (C6H2Me3)2P−C6F4−B(C6F5)2 but unlike the latter cannot split dihydrogen. Moreover, attempts to prepare a Ge/B analogue of the zwitterion (C6H2Me3)2HP−C6F4−BH(C6F5)2 by protonation of borate 8 resulted in immediate elimination of H2.

Chemical Synthesis of Human Milk Oligosaccharides: para‐Lacto‐N‐hexaose and para‐Lacto‐N‐neohexaose

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Chemical Synthesis of Human Milk Oligosaccharides: para-Lacto-N-hexaose and para-Lacto-N-neohexaose

Chemical synthesis of two common core human milk oligosaccharides—para-lacto-N-hexaose (pLNH) and para-lacto-N-neohexaose (pLNnH)—using a convergent 3+3 approach has been reported.


Abstract

Human milk oligosaccharides (HMO) have emerged as a very active area of research in glycoscience and nutrition. HMO are involved in the early development of infants and may help to prevent certain diseases. The development of chemical methods for obtaining individual HMO aids the global effort dedicated to understanding the roles of these biomolecules. Reported herein is the chemical synthesis of two common core hexasaccharides found in human milk, i. e. para-lacto-N-hexaose (pLNH) and para-lacto-N-neohexaose (pLNnH). After screening multiple leaving groups and temporary protecting group combinations, a 3+3 convergent coupling strategy was found to work best for obtaining these linear glycans.

Reductive Amination of Levulinic Acid to Pyrrolidones: Key Step in Biomass Valorization towards Nitrogen‐Containing Chemicals

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Reductive Amination of Levulinic Acid to Pyrrolidones: Key Step in Biomass Valorization towards Nitrogen-Containing Chemicals

Catalytic conversion of Biomass-derived Levulinic Acid! This review attempts to showcase an efficient catalytic system of levulinic acid reductive amination into pyrrolidones with core concerns on catalyst design and conditional optimization.


Abstract

Nowadays, the field of biomass conversion is gradually moving towards an encouraging stage. The preparation of nitrogen-containing chemicals using various biomass resources instead of fossil resources do not only reduce carbon emissions, but also diversify the products of biomass conversion, thus increasing the economic competitiveness of biomass refining systems. Levulinic acid (LA) can be used as a promising intermediate in biomass conversion for further synthesis of pyrrolidone via reductive amination. However, there are still many critical issues to be solved. Particularly, the specific effects of catalysts on the performance of LA reductive amination have not been sufficiently revealed, and the potential impacts of key conditional factors have not been clearly elucidated. In view of this, this review attempts to provide theoretical insights through an in-depth interpretation of the above key issues. The contribution of catalysts to the reductive amination of LA as well as the catalyst structural preferences for improving catalytic performance are discussed. In addition, the role of key conditional factors is discussed. The insights presented in this review will contribute to the design of catalyst nanostructures and the rational configuration of green reaction conditions, which may provide inspiration to facilitate the nitrogen-related transformation of more biomass platform molecules.

Two‐component polymer sorting to obtain high‐purity s‐SWCNTs for all‐carbon photodetectors

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Two-component polymer sorting to obtain high-purity s-SWCNTs for all-carbon photodetectors

Preparation of semiconducting carbon nanotubes with high purity and yield by two-component polymer sorting and its application in photodetectors. Poly[N-(1-octylnonyl)-9H-carbazol-2,7-diyl] (PCz) was used to disperse and selectively wrap large-diameter s-SWCNTs, with poly(9,9-n-dihexyl-2,7-fluorenyl-alternative-9-phenyl-3,6-carbazole) (PDFP) added as an enhancing molecule. Although PDFP itself is not selective for s-SWCNTs, the combined effect of PCz and PDFP increased sorting efficiency by 4-fold. Field-effect transistors and photodetectors made from the sorted s-SWCNTs exhibited excellent semiconductor properties and broad-spectrum detection, with good long-term stability.


Abstract

The advancement of carbon-based electronics is reliant on the development of semiconducting carbon nanotubes with high purity and yield. We developed a new extraction strategy to efficiently sort SWCNTs with superior yields and purity. The approach uses two polymers, poly[N-(1-octylnonyl)-9H-carbazol-2,7-diyl](PCz) and poly(9,9-n-dihexyl-2,7-fluorene-alt-9-phenyl-3,6-carbazole)(PDFP), and two sonication processes to eliminate surface polymer contamination. PCz selectively wraps large-diameter s-SWCNTs, with PDFP added as an enhancing molecule to increase sorting efficiency at 4-fold compared to the efficiency of only PCz alone sorting. The purity of the sorted s-SWCNTs was confirmed to be above 99 % using absorption and Raman spectra. Field-effect transistors and photodetectors made from the sorted s-SWCNTs exhibited excellent semiconductor properties and broad-spectrum detection, with good long-term stability. Furthermore, a photodetector using large-tube diameter s-SWCNTs achieved broad-spectrum detection, which the photoresponsivity is 0.35 mA/W and the detectivity is 4.7×106 Jones. The s-SWCNTs/graphene heterojunction photodetector achieved a photoresponsivity of 3 mA/W and a detectivity of 6.3×106 Jones. This new strategy provides a promising approach to obtain high-purity and high-yield s-SWCNTs for carbon-based photodetectors.

Anion‐Dependent Reactivity of Mono‐ and Dinuclear Boron Cations

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Anion-Dependent Reactivity of Mono- and Dinuclear Boron Cations

If NHC-stabilized borenium ions [NHC−BH2]+ and [PF6]− take the same bus, they will get off neutralized and with a noticeable change, i. e., as NHC−BF3 and PH2F3. However, if tetrakis(perfluoro-tert-butoxy)aluminate is the second passenger, the anion remains untouched and a bis(boronium) or a bis(borenium) ion can enjoy the journey.


Abstract

The dinuclear bis(N-heterocyclic carbene) borane adduct 2 rapidly reacts with tritylium salts at room temperature but the outcome is strongly impacted by the respective counter-ion. Using tritylium tetrakis(perfluoro-tert-butoxy)aluminate affords – depending on the solvent – either the bis(boronium) ion 4 or the hydride-bridged dication 5. In case of tritylium hexafluorophosphate, however, H/F exchange occurs between boron and phosphorus yielding the dinuclear BF3 adduct 3 along with phosphorus dihydride trifluoride. H/F exchange also takes place when using the mononuclear N-heterocyclic carbene BH3 adduct 6 and hence provides a facile route to PH2F3, which is usually synthesized in more complex reaction sequences regularly involving toxic hydrogen fluoride. DFT calculations shed light on the H/F exchange between the borenium ion and the [PF6]− counter-ion and the computed mechanism features only small barriers in line with the experimental observations.