Abstract N‐containing molecules are mostly derived from ammonia (NH3). Ammonia activation has been demonstrated for single transition metal centers as well as for low‐valent main group species. Phosphinidenes, mono‐valent phosphorus species, can be stabilized by phosphines, giving so‐called phosphanylidenephosphoranes of the type RP(PR′3). We demonstrate the facile, metal‐free NH3 activation using ArP(PMe3), affording for the first time isolable secondary aminophosphines ArP(H)NH2. DFT studies reveal that two molecules of NH3 act in concert to facilitate an NH3 for PMe3 exchange. Furthermore, H2NR and HNR2 activation is demonstrated.

Metal‐Free N−H Bond Activation by Phospha‐Wittig Reagents

Radio-frequency magnetron sputtered thin-film La0.5Sr0.5Co0.95Nb0.05O3-δ perovskite electrodes for intermediate temperature symmetric solid oxide fuel cell (IT-SSOFC)

Abstract A geometrically constrained phosphenium cation in bis(pyrrolyl)pyridine based NNN pincer type ligand (1+ ) was synthesized, isolated and its preliminary reactivity was studied with small molecules. 1+ reacts with MeOH and Et2NH, activating the O−H and N−H bonds via a P‐center/ligand assisted path. The reaction of 1+ with one equiv. of H3NBH3 leads to its dehydrogenation producing 5. Interestingly, reaction of 1+ with an excess H3NBH3 leads to phosphinidene (PI) species coordinating to two BH3 molecules (6). In contrast, [1+ ][OTf] reacts with Et3SiH by hydride abstraction yielding 1‐H and Et3SiOTf, while [1+ ][B(C6F5)4] reacts with Et3SiH via an oxidative addition type reaction of Si−H bond to P‐center, affording a new PV compound (8). However, 8 is not stable over time and degrades to a complex mixture of compounds in matter of minutes. Despite this, the ability of [1+ ][B(C6F5)4] to activate Si−H bond could still be tested in catalytic hydrosilylation of benzaldehyde, where 1+ closely mimics transition metal behaviour.

Dual Reactivity of a Geometrically Constrained Phosphenium Cation

The synthesis of degradable vinyl polymer nanoparticles/latexes in aqueous dispersed media is receiving much attention, particularly for biomedical applications and plastic pollution control, as it can circumvent the severe limitations associated with the emulsification of preformed degradable polymers. Polymerization-induced self-assembly (PISA), which enables the in situ formation of aqueous suspensions of diblock copolymer nano-objects of high solids content, has become a very popular polymerization process due to its many advantages in terms of simplicity, robustness, scalability, and versatility. However, the preparation of degradable vinyl polymer nanoparticles by direct aqueous PISA has never been reported. This severely limits the use of PISA in biomedical and environmental applications. Herein, we report the first aqueous emulsion PISA able to generate degradable vinyl polymer nanoparticles. It relies on radical ring-opening polymerization-induced self-assembly (rROPISA) of traditional vinyl monomers (n-butyl acrylate or styrene) with dibenzo[c,e]oxepane-5-thione (DOT), a thionolactone that features high stability in protic solvents and favorable reactivity with many vinyl monomers and is a precursor of labile thioester groups in the main chain. Stable aqueous suspensions of thioester-containing diblock copolymer nanoparticles were obtained with both vinyl monomers. Extensive degradation of the copolymers and the nanoparticles was successfully demonstrated under aminolytic or basic conditions. Given the success of the PISA process within the polymer community, this work has the potential to greatly expand its use in many areas, from nanomedicine (providing applicability to biocompatible vinyl polymers) to degradable coatings and sustained materials. 

/pdf/degradable-vinyl-copolymer-nanoparticles-latexes-by-aqueous-j1ebqesx.pdf

Degradable Vinyl Copolymer Nanoparticles/Latexes by Aqueous Nitroxide-Mediated Polymerization-Induced Self-Assembly

We report the preparation of degradable polymer networks by conventional free radical copolymerization of n-butyl acrylate with a crosslinker (1 mol %) and dibenzo[c,e]oxepane-5-thione (DOT) as a strand-cleaving comonomer. Addition of only 4 mol % of DOT imparts the synthesized networks with full degradability by aminolysis, whereas gels with less DOT (2–3 mol %) cannot be degraded. This data confirms the recently proposed reverse gel-point model for networks prepared by free radical polymerization and demonstrates the importance of considering copolymerization kinetics when designing fully degradable gels. Notably, even though DOT significantly slows down the polymerization and delays gelation, it has a minimal effect on physical properties of the networks such as shear storage modulus, equilibrium swelling ratio, glass transition temperature, or thermal stability. 

https://pubs.acs.org/doi/pdf/10.1021/acs.macromol.2c01140

Fully Degradable Polyacrylate Networks from Conventional Radical Polymerization Enabled by Thionolactone Addition

With the escalating demand for sustainable energy sources, the sodium-ion batteries (SIBs) appear as a pragmatic option to develop large energy storage grid applications in contrast to existing lithium-ion batteries (LIBs) owing to the availability of cheap sodium precursors. Nevertheless, the commercialization of SIBs has not been carried out so far due to the inefficacies of present electrode materials, particularly cathodes. Thus, from a future application perspective, this short review highlights the intrinsic challenges and corresponding strategies for the extensively researched layered transition metal oxides, polyanionic compounds, and Prussian blue analogues. In addition, the commercial feasibility of existing materials considering relevant parameters is also discussed. The insights provided in the current review may serve as an aid in designing efficient cathode materials for state-of-the-art SIBs.

Understanding the Design of Cathode Materials for Na-Ion Batteries

Conversion of CO2 to Formate using Activated Carbon Fiber-supported g-C3N4-NiCoWO4 Photoanode in a Microbial Electrosynthesis System

Biocompatibility and Physiological Thiolytic Degradability of Radically Made Thioester-Functional Copolymers: Opportunities for Drug Release

The synthesis of P,N-phosphaalkene ligands, py-CH═PMes* (1, py = 2-pyridyl, Mes* = 2,4,6-tBu-C6H2) and the novel quin-CH═PMes* (2, quin = 2-quinolinyl) is described. The reaction with [Rh(μ-Cl)cod]2 produces Rh(I) bis(phosphaalkene) chlorido complexes 3 and 4 with distorted trigonal bipyramidal coordination environments. Complexes 3 and 4 show a pronounced metal-to-ligand charge transfer (MLCT) from Rh into the ligand P═C π* orbitals. Upon heating, quinoline-based complex 4 undergoes twofold C-H bond activation at the o-tBu groups of the Mes* substituents to yield the cationic bis(phosphaindane) Rh(I) complex 5, which could not be observed for the pyridine-based analogue 3. Using sub- or superstoichiometric amounts of AgOTf the C-H bond activation at an o-tBu group of one or at both Mes* was detected, respectively. Density functional theory (DFT) studies suggest an oxidative proton shift pathway as an alternative to a previously reported high-barrier oxidative addition at Rh(I). The Rh(I) mono- and bis(phosphaindane) triflate complexes 6 and 7, respectively, undergo deprotonation at the benzylic CH2 group of the phosphaindane unit in the presence of KOtBu to furnish neutral, distorted square-planar Rh(I) complexes 8 and 9, respectively, with one of the P,N ligands being dearomatized. All complexes were fully characterized, including multinuclear NMR, vibrational, and ultraviolet-visible (UV-vis) spectroscopy, as well as single-crystal X-ray and elemental analysis.

Priyanka Gupta

Papers

Understanding the Design of Cathode Materials for Na-Ion Batteries

Metal‐Free N−H Bond Activation by Phospha‐Wittig Reagents

Conversion of CO2 to Formate using Activated Carbon Fiber-supported g-C3N4-NiCoWO4 Photoanode in a Microbial Electrosynthesis System

Biocompatibility and Physiological Thiolytic Degradability of Radically Made Thioester-Functional Copolymers: Opportunities for Drug Release

Synthesis, Coordination Chemistry, and Mechanistic Studies of P,N-Type Phosphaalkene-Based Rh(I) Complexes.