A versatile post-synthetic modification strategy to functionalize a high surface area microporous network (MPN-OH) by bioorthogonal inverse electron-demand Diels-Alder (IEDDA) ligation is presented. While the polymer matrix is modified with a readily accessible norbornene isocyanate (Nb-NCO), a set of functional entities, presenting the robust asymmetric 1,2,4,5-tetrazine (Tz) allows easy functionalization of the MPN by chemoselective Nb/Tz ligation. A generic route is demonstrated, modulating the internal interfaces by introducing carboxylates, amides or amino acids as well as an oligopeptide d-Pro-Pro-Glu organocatalyst. The MPN-Peptide construct largely retains the catalytic activity and selectivity in an enantioselective enamine catalysis, proving remarkable availability in different solvents, offers heterogeneous organocatalysis in bulk and shows stability in recycling settings.
Why The Perfectly Symmetric Cobalt‐Pentapyridyl Loses the H2 Production Challenge: Theoretical Insight into Reaction Mechanism and Reduction Free Energies
Researchers have extensively investigated photo-catalytic water reduction utilizing Cobalt-based catalysts with poly-pyridyl ligands. While catalysts exhibiting distorted poly-pyridyl ligand demonstrate higher H2 production yields, those with ideal octahedral coordination display poor performance. This outcome suggests the crucial role of ligand framework in catalytic activity, yet reasons behind the disparity in H2 production rates for catalysts with octahedral geometries remain unclear. We theoretically examined the water reduction mechanism of Co-based poly-pyridyl catalyst, CoPy5, having perfect octahedral coordination. We clarified the effect of octahedral coordination by utilizing each intermediate step of ECEC mechanism. We determined spin states, solvent response, electronic structures, and reduction free energies. CoPy5 with perfect octahedral coordination, alongside its distorted counterparts, exhibit similar spin states as the reaction progresses through each intermediate step. However, the first reduction free energy obtained for the CoPy5 is slightly higher than that of its distorted counterparts. Following the second protonation, resulting H2 molecule experiences limited diffusion from the Co center due to the compact structure of the CoPy5, which blocks the Co center for the next H2 production cycle. Catalysts having distorted octahedral geometries facilitate fast removal of H2 into the solvent. Thus, the reaction center becomes immediately available for subsequent H2 production.
Chain‐walking polymerization of ethylene and 1‐octene with ortho‐phenyl‐based α‐diimine Ni (II) catalysts
The ortho-phenyl-substituted Ni catalysis system based on α-diimine with variable electronic nature are highly active toward ethylene polymerization to synthesize high molecular weight polyethylene, and conducted the chain-walking polymerization of 1-octene to produce highly branched polyolefins.
A class of ortho-phenyl-substituted Ni (II) α-diimine complexes with variable electronic nature in the 4-phenyl position, {[(4-Me-2-(4-R-C6H4)C6H3N=C)2Naphth]NiBr2, R = OMe (C1); R = Me (C2); R = H (C3)}, was prepared and characterized. These nickel dibromide complexes were confirmed by X-ray crystallography analysis and crystallized as a centrosymmetric bromine-bridged dimer in a distorted tetrahedral geometry at the two Ni (II) centers connected by a four-membered ring. Because of the conjugation effect and steric hindrance effect of ortho-phenyl substituent, these Ni-Et2AlCl systems via controlled chain-walking ethylene polymerization performed with high catalytic activities of up to 3.10 × 106 g PE (mol Ni h)−1 to yield high molecular weight branched PEs with narrow M w/M n values (PDI ≤ 2.39). This Ni (II) system also conducted the chain-walking polymerization of 1-octene, resulting in highly branched polyolefins (up to 107 branches/1000C).
Novel core–shell magnetic nanoparticles@Zeolitic imidazolate with glycerol‐nickel for the synthesis of dihydropyrimidinones
A novel Fe3O4-ZIF-8@Glycerol-Ni nanocatalyst was synthesized. Highly efficient catalytic activity was acquired for synthesizing dihydropyrimidinones with ethanol as suitable solvent in the reaction.
The present study reported a novel and eco-friendly synthesis of Fe3O4@ZIF-8@Glycerol-Ni nanocatalyst via a multistep process. The as-prepared catalyst was used due to its high efficiency, low cost, and biocompatibility for the fabrication of dihydropyrimidinones by Biginelli multicomponent reactions of aryl aldehyde, ethyl acetoacetate, and urea under ambient status. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmet-Teller (BET), vibrating sample magnetometry (VSM), scanning electron microscopy and energy dispersive X-ray (SEM-EDS), inductively coupled plasma (ICP), elemental mapping analysis (EMA), thermogravimetric analysis (TGA), Raman, and transmission electron microscopy (TEM) techniques were successfully utilized to evaluate the nanocatalyst. The advent of the peaks confirmed the presence of nickel on the catalyst's surface due to the oxygen and nickel, and the nanoparticle size is 10–15 nm. Eventually, nano-heterogeneous catalyst exhibits high performance as well as good selectivity in the synthesis of dihydropyrimidinones. Also, it can be recycled up to multiple fresh runs with no significant loss of catalytic efficiency.
[ASAP] Machine Learning Analysis of Raman Spectra To Quantify the Organic Constituents in Complex Organic–Mineral Mixtures
Analytical Chemistry
DOI: 10.1021/acs.analchem.3c02348
Supercritical CO2 Mediated Multi‐scale Structural Engineering in PdCu/C for Boosting Electrocatalytic Formic Acid Oxidation
We found that supercritical carbon dioxide could mediate multi-scale structure engineering in PdCu/C nanocatalysts, including defect engineering, phase engineering, morphology engineering and substrate engineering. The achieved PdCu/C with amorphous surface, BCC phase, nanoflake morphology and curved carbon substrate shows ultrahigh mass activity for formic acid oxidation as high as 3624 mA/mgPd.
Abstract
Nowadays, PdCu alloy nanocatalyst with excellent performance in electrocatalytic formic acid oxidation reaction (FAOR) is believed to have great potential in application of direct formic acid fuel cells. Structural engineering has shown great success in achieving PdCu alloys with high catalytic performance, while achievement of multi-scale structure engineering is still a great challenge. In this work, we found that supercritical carbon dioxide (SC CO2) could lead to multi-scale structure engineering in PdCu/C nanocatalysts, including surface defect engineering, phase engineering, morphology engineering and substrate structure engineering. With the assistance of SC CO2, amorphous phase in surface, the transformation from face-centered cubic (FCC) to body-centered cubic (BCC) phase, the morphology of 2D nanoflakes and the curved carbon as substrate all contribute to the ultrahigh mass activity for electrocatalytic FAOR as 3624.3 mA/mgPd in PdCu/C nanocatalysts, which is the highest value in PdCu alloy reported up to now. Therefore, this work not only displays the great potential of SC CO2 in multi-scale structure engineering, but also provides new inspiration of material design to achieve nanocatalysts with ultrahigh catalytic performance.
Ionization, intrinsic basicity, and intrinsic acidity of unsaturated diols of astrochemical interest: 1,1‐ and 1,2‐ethenediol: A theoretical survey
The structure, stability, and bonding characteristics of 1,1- and 1,2-ethenediol, their radical cations, and their protonated and deprotonated species were investigated using high-level ab initio G4 calculations.
Abstract
The structure, stability, and bonding characteristics of 1,1- and 1,2-ethenediol, their radical cations, and their protonated and deprotonated species were investigated using high-level ab initio G4 calculations. The electron density of all the neutral and charged systems investigated was analyzed using the QTAIM, ELF, and NBO approaches. The vertical ionization potential (IP) of the five stable tautomers of 1,2-ethenediol and the two stable tautomers of 1,1-ethenediol go from 11.81 to 12.27 eV, whereas the adiabatic ones go from 11.00 to 11.72 eV. The adiabatic ionization leads to a significant charge delocalization along the O-C-C-O skeleton. The most stable protonated form of (Z)-1,2-ethenediol can be reached by the protonation of both the anti-anti and the syn-anti conformers, whereas the most stable deprotonated form arises only from the syn-anti one. Both charged species are extra-stabilized by the formation of an O-H···O intramolecular hydrogen bond (IHB) which is not found in the neutral system. (Z)-1,2-ethenediol is predicted to be less stable, less basic, and more acidic than its cis-glycolaldehyde isomer. The most stable protonated species of (E)-1,2-ethenediol comes from its syn-syn conformer, although the anti-anti conformer is the most basic one. Contrarily, the three conformers yield a common deprotonated species, so their acidity follows exactly their relative stability. Again, the (E)-1,2-ethenediol is predicted to be less stable, less basic, and more acidic than its trans-glycolaldehyde isomer. Neither the neutral nor the protonated or the deprotonated forms of 1,1-ethenediol show the formation of any O-H···O IHB. The most stable protonated species is formed by the protonation of any of the two tautomers, but the most stable deprotonated form arises exclusively from the syn-anti neutral conformer. The conformers of 1,1-ethenediol are much less stable and significantly less basic than their isomer, acetic acid, and only slightly more acidic.
C,N‐Diarylformamidines as Valuable Building Blocks in the Synthesis of Heterocyclic Compounds
This review is devoted to the heterocyclization of C,N-diarylformamidines and covers publications from 1999 to 2022. The comprehensive information collected enables other researchers to quickly understand the possibility of constructing various complex heterocycles from simple, readily available reagents.
Abstract
Obtaining highly functionalized heterocyclic structures is an important topic of modern organic synthesis, as it reveals the possibility of constructing more complex systems and therefore, expanding the range of various drugs. Aiming at synthesizing complex molecules from simple and readily available reagents, the modification of C,N-diarylformamidines, well known in medicinal chemistry, is of great interest. This article reviews comprehensively the field of C,N-diarylformamidine chemistry and covers publications on this topic from 1999 to 2022.
PPh3‐Mediated Nucleophilic Sulfonation of Sulfonyl Chlorides with Arynes: Access to Manifold Aryl Sulfones
A novel PPh3-mediated nucleophilic sulfonation of sulfonyl chlorides with arynes has been demonstrated. This protocol exhibits broad functional group tolerance and provides a direct approach to a variety of aryl and alkyl sulfones.
Abstract
Sulfonyl chlorides are a class of cheap and readily available basic chemicals, which have routinely served as electrophilic reagents in their chemical transformations. Herein, we disclose a novel PPh3-mediated nucleophilic sulfonation method of sulfonyl chlorides with arynes. Different from the classical P(III)-mediated reductive deoxygenation reaction of sulfonyl chlorides, the valence state of the sulfur atom has not been changed. This protocol exhibits broad functional group tolerance and provides a direct approach to a variety of aryl and alkyl sulfones.
Host‐Guest Complexes of Pillar[5]arene as Components for Supramolecular Light‐Harvesting Systems with Tunable Fluorescence
![Host-Guest Complexes of Pillar[5]arene as Components for Supramolecular Light-Harvesting Systems with Tunable Fluorescence](https://onlinelibrary.wiley.com/cms/asset/3161adbc-ec10-4376-adcb-240a9b139634/cplu202300431-toc-0001-m.png)
A supramolecular light-harvesting system with high donor/acceptor ratio has been constructed from pillar[5]arene-based host-guest complex in water. The system exhibits tunable fluorescence emission and can be used as fluorescent ink for information encryption.
Abstract
A guest molecule containing a short alkyl spacer between the tetraphenylethylene group and the methylpyridinium group was designed and synthesized. After complexation with a water-soluble pillar[5]arene, the resulting host-guest complex can further self-assemble into fluorescence-emitting nanoparticles in water. By loading a commercially available dye Rhodamine 6G into the nanoparticles, an efficient artificial light-harvesting system with high donor/acceptor ratios (>400/1) was successfully constructed. The obtained systems show considerable antenna effects with values of more than 10 times. The system also exhibits tunable fluorescence emission behavior and can be used as a fluorescent ink for information encryption.