Amine-functionalized siloxane oligomer facilitated synthesis of subnanometer colloidal Au particles
Amine-functionalized siloxane oligomers were synthesized and used successfully to prepare colloidal Au particles smaller than 1 nm.
Wang, Zhen↗
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Nickel Phosphine Catalysts with Pendant Amines for Electrocatalytic Oxidation of Alcohols
Nickel phosphine complexes with pendant amines have been found to be electrocatalysts for the oxidation of primary and secondary alcohols, with turnover frequencies as high as 3.3 s-1. These complexes are the first electrocatalysts for alcohol oxidation based on non-precious metals, which will be critical for use in fuel cells. The research by CJW, ESW, and AMA was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. The research by JASR was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.
Alcohol Oxidation↗
Postmodification of a supramolecular organic framework: Visible-light-induced recyclable heterogeneous photocatalysis for the reduction of azides to amines
In this work, we present the postmodification of a diamondoid 3D supramolecular organic framework (SOF) to append [Ru(BPY) 3 ] 2+ groups through the formation of a hydrazone bond. The resulting SOF works as an efficient recyclable heterogeneous catalyst for visible-light-induced reduction of aromatic azides to amines.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Iron-catalyzed urea synthesis: dehydrogenative coupling of methanol and amines
An iron catalyzed method for selective urea synthesis is described. This approach couples methanol and amines to generate diverse organic ureas.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Stable immobilized amine sorbents for heavy metal and REE removal from industrial wastewaters
Stable and immobilized amine sorbents can simultaneously remove/recover cationic and oxyanionic toxic metals plus valuable rare earth elements from industrial and mining effluents prior to discharging into environmental water systems.<
54 ENVIRONMENTAL SCIENCES↗
Multi-state amine sensing by electron transfers in a BODIPY probe
Photoinduced electron transfer sets up the BODIPY probe for multi-state amine sensing by single-electron transfer then collisional quenching.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Ti-catalyzed ring-opening oxidative amination of methylenecyclopropanes with diazenes
The ring-opening oxidative amination of methylenecyclopropanes (MCPs) with diazenes catalyzed by py 3 TiCl 2 (NR) complexes is reported.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Surface ligands enhance the catalytic activity of supported Au nanoparticles for the aerobic α-oxidation of amines to amides
Surface ligands control the electronic properties of supported Au nanoparticles and thereby regulate their catalytic activity for the selective aerobic oxidation of amines to amides.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Robust binding between secondary amines and Au electrodes
A robust binding between secondary amines and Au atomic contacts is achieved through the creation of Au adatoms by the use of a wax-coated tip.
Chemistry↗
Correction: Improving the direct air capture capacity of grafted amines via thermal treatment
Correction for ‘Improving the direct air capture capacity of grafted amines via thermal treatment’ by Melinda L. Jue et al. , Chem. Commun. , 2024, 60 , 7077–7080, https://doi.org/10.1039/D4CC01634C.
Jue, Melinda L.↗
C–H amination chemistry mediated by trinuclear Cu( i ) sites supported by a ligand scaffold featuring an arene platform and tetramethylguanidinyl residues
A crown-shaped Cu 3 Cl 3 fragment captured by a ligand that features tetramethylguanidinyl residues and an apically oriented arene platform gives rise to a potent benzylic and tert -C–H bond amination catalyst via a computed dicopper nitrene oxidant.
Sharma, Meenakshi↗
Discerning molecular-level CO 2 adsorption behavior in amine-modified sorbents within a controlled CO 2 /H 2 O environment towards direct air capture
Sorbents designed for direct air capture (DAC) play a crucial role in the pursuit of achieving net-zero carbon dioxide emissions. This study elucidates CO 2 adsorption from dilute, humidified CO 2 streams onto an amine-modified benchmark DAC adsorbent via solid-state NMR spectroscopy. Various NMR techniques, including 1D 1 H MAS, 13 C MAS, 2D 1 H– 13 C HETCOR NMR, and 1 H R 2 and R 1ρ relaxometry reveal the impact of CO 2 partial pressure and H 2 O on CO 2 adsorption behavior. Here we find that CO 2 concentration governs the stepwise formation of ammonium carbamate, carbamic acid, and physisorbed CO 2 , where relative humidity (RH) at a desired low (<400 ppm) CO 2 loading affects total CO 2 uptake. The relaxation studies reveal the cooperative or competitive nature of H 2 O–CO 2 sorption in CO 2 -dilute humid gas, and in particular polymer swelling upon humidification. From those results, we demonstrate that the observed absorption capacity enhancement by humidity is caused by pore opening due to sorbent swelling, and not by bicarbonate formation. This NMR-discerned speciation provides insights into sorption behavior at different RHs in dilute CO 2 gas streams, simulating real-world atmospheric conditions, and governs the design of efficient and adaptable material-process combinations for solid sorbent DAC.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Dense nitrogen-rich energetic materials: A study of 5,5{sup ′}-(1H-tetrazolyl)amine
5,5{sup ′}-(1H-tetrazolyl)amine (BTA), a nitrogen rich molecular solid has been investigated under compression at room temperature. Powder x-ray diffraction using synchrotron radiation and micro-Raman spectroscopy were carried out to pressures up to 12.9 GPa. BTA conserves the crystalline structure of its room condition phase up to the highest pressure, i.e., an orthorhombic unit cell (Pbca). A fit of the isothermal compression data to the Birch-Murnaghan equation of state reveals the high compressibility of BTA. An analysis of the volume change with pressure yields a bulk modulus and its derivative similar to that of high-nitrogen content molecular crystals. Upon laser heating to approximately 1100 K, the sample decomposed while pressurized at 2.1 GPa, resulting in a graphitic compound. Finally, numerical simulations demonstrate that the minimum energy conformation is not experimentally observed since a higher energy conformation allows for a more stable dense packing of the BTA molecules.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Electrochemical characterization of aminated acrylic conducting polymer
New attempt has been made to synthesize aminated acrylic conducting polymer (AACP) using precursor of phenylvinylsulfoxide (PVS). The process was conducted via the integration of microemulsion and photopolymerization techniques. It has been utilized for covalent immobilization of amino groups by the adding of N-achryiloxisuccinimide (NAS). Thermal eliminating of benzene sulfenic acids from PVS has been done at 250 °C to form electroactive polyacetylene (PA) segment. Characterization of AACP has been conducted using fourier transform infrared (FTIR), scanning electron microscopy (SEM) and linear sweep cyclic voltammetry (CV). A range of 0.3-1.25μm particle size obtained from SEM characterization. A quasi-reversible system performed as shown in electrochemical study.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Pore diameter dependence of catalytic activity: p -nitrobenzaldehyde conversion to an aldol product in amine-functionalized mesoporous silica
The reaction yield for conversion of p-nitrobenzaldehyde (PNB) to an aldol product in amine-functionalized mesoporous silica nanoparticles (MSN) exhibits a 20-fold enhancement for a modest increase in pore diameter, d. This enhanced catalytic activity is shown to reflect a strong increase in the “passing propensity,” P, of reactant and product species inside the pores. We find that P ≈ 0, corresponding to single-file diffusion, applies for the smallest d which still significantly exceeds the linear dimensions of PNB and the aldol product. However, in this regime of narrow pores, these elongated species must align with each other and with the pore axis in order to pass. Thus, P reflects both translational and rotational diffusion. Langevin simulation accounting for these features is used to determine P versus d. The results are also augmented by analytic theory for small and large d where simulation is inefficient. The connection with the catalytic activity and yield is achieved by the incorporation of results for P into a multi-scale modeling framework. Specifically, we apply a spatially coarse-grained (CG) stochastic model for the overall catalytic reaction-diffusion process in MSN. Pores are treated as linear arrays of cells from the ends of which species adsorb and desorb, and between which species hop and exchange, with the exchange rate reflecting P. CG model predictions including yield are assessed by Kinetic Monte Carlo simulation.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Simulating excited-state complex ensembles: Fluorescence and solvatochromism in amine-arene exciplexes
Exciplexes are excited-state complexes formed as a result of partial charge transfer from the donor to the acceptor species when one moiety of the donor–acceptor pair is electronically excited. The arene–amine exciplex formed between oligo-(p-phenylene) (OPP) and triethylamine (TEA) is of interest in the catalytic photoreduction of CO2 because it can compete with complete electron transfer to the OPP catalyst. Therefore, formation of the exciplex can hinder the generation of a radical anion OPP·− necessary for subsequent CO2 reduction. We report an implementation of a workflow automating quantum-chemistry calculations that generate and characterize an ensemble of structures to represent this exciplex state. We use FireWorks, Pymatgen, and Custodian Python packages for high-throughput ensemble generation. The workflow includes time-dependent density functional theory optimization, verification of excited-state minima, and exciplex characterization with natural transition orbitals, exciton analysis, excited-state Mulliken charges, and energy decomposition analysis. Fluorescence spectra computed for these ensembles using Boltzmann-weighted contributions of each structure agree better with experiment than our previous calculations based on a single representative exciplex structure [Kron et al., J. Phys. Chem. A 126, 2319–2329 (2022)]. The ensemble description of the exciplex state also reproduces an experimentally observed red shift of the emission spectrum of [OPP-4–TEA]* relative to [OPP-3–TEA]*. The workflow developed here streamlines otherwise labor-intensive calculations that would require significant user involvement and intervention.
Chemistry↗
Reactivity of radiolytically and photochemically generated tertiary amine radicals towards a CO 2 reduction catalyst
Homogeneous solar fuels photocatalytic systems often require several additives in solution with the catalyst to operate, such as a photosensitizer (PS), Brønsted acid/base, and a sacrificial electron donor (SED). Tertiary amines, in particular triethylamine (TEA) and triethanolamine (TEOA), are ubiquitously deployed in photocatalysis applications as SEDs and are capable of reductively quenching the PS’s excited state. Upon oxidation, TEA and TEOA form TEA •+ and TEOA •+ radical cations, respectively, which decay by proton transfer to generate redox non-innocent transient radicals, TEA • and TEOA • , respectively, with redox potentials that allow them to participate in an additional electron transfer step, thus resulting in net one-photon/two-electron donation. However, the properties of the TEA • and TEOA • radicals are not well understood, including their reducing powers and kinetics of electron transfer to catalysts. Herein, we have used both pulse radiolysis and laser flash photolysis to generate TEA • and TEOA • radicals in CH 3 CN, and combined with UV/Vis transient absorption and time-resolved mid-infrared spectroscopies, we have probed the kinetics of reduction of the well-established CO 2 reduction photocatalyst, fac-ReCl(bpy)(CO) 3 (bpy = 2,2'-bipyridine), by these radicals [k TEA• = (4.4 ± 0.3) × 10 9 M –1 s –1 and k TEOA• = (9.3 ± 0.6) × 10 7 M –1 s –1 ]. The ~50× smaller rate constant for TEOA • indicates, that in contrast to a previous assumption, TEA • is a more potent reductant than TEOA • (by ~0.2 V, as estimated using the Marcus cross relation). This knowledge will aid in the design of photocatalytic systems involving SEDs. Furthermore, we also show that TEA can be a useful radiolytic solvent radical scavenger for pulse radiolysis experiments in CH 3 CN, effectively converting unwanted oxidizing radicals into useful reducing equivalents in the form of TEA • radicals.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Synthesis of a copper-supported triplet nitrene complex pertinent to copper-catalyzed amination
Terminal copper-nitrenoid complexes have inspired interest in their fundamental bonding structures as well as their putative intermediacy in catalytic nitrene-transfer reactions. Here, we report that aryl azides react with a copper(I) dinitrogen complex bearing a sterically encumbered dipyrrin ligand to produce terminal copper nitrene complexes with near-linear, short copper–nitrenoid bonds [1.745(2) to 1.759(2) angstroms]. X-ray absorption spectroscopy and quantum chemistry calculations reveal a predominantly triplet nitrene adduct bound to copper(I), as opposed to copper(II) or copper(III) assignments, indicating the absence of a copper−nitrogen multiple-bond character. Employing electron-deficient aryl azides renders the copper nitrene species competent for alkane amination and alkene aziridination, lending further credence to the intermediacy of this species in proposed nitrene-transfer mechanisms.
Carsch, Kurtis M. (ORCID:0000000344327518)↗