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Digital light processing (DLP) of structurally complex poly(ethylene glycol) (PEG) hydrogels with high mechanical toughness represents a long-standing challenge in the field of 3D printing. Here, we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP. Instead of using aqueous solutions of photo-crosslinkable monomers, PEG macromonomer melts were first printed in the absence of water, resulting in bulk PEG networks. Then, post-printing swelling of the printed networks was achieved in water, producing high-fidelity 3D hydrogels with complex structures. By employing a dual-macromonomer resin containing a PEG-based four-arm macrophotoinitiator, "all-PEG" hydrogel constructs were produced with compressive toughness up to 1.3 MJ m(-3). By this approach, porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated, and the scaffold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells. This study highlights the promises of heat-assisted DLP of PEG photopolymers for hydrogel fabrication, which may accelerate the development of 3D tissue-like constructs for regenerative medicine., Aggregate

Reaction of the imidazolium-stabilized diphosphete-diide IDP with trityl phosphaalkyne affords a mixture which contains the molecules 1 a and 1 b with a central C3P3 core, which formally carries a two-fold negative charge. In order to avoid the formation of an antiaromatic 8π electron system within a conjugated dianionic six-membered [C3P3]2− ring, 1 a adopts a bicyclic [3.1.0] and 1 b a tricyclic [2.2.0.0] structure which are in a dynamic equilibrium. 1 a, b can be reversibly oxidized to a triphosphinine dication [5]2+ with a central flat aromatic six-membered C3P3 ring. This two-electron redox reaction occurs in two single-electron transfer steps via the 7π-radical cation [4]⋅+, which could also be isolated and fully characterized. The profound reversible structural change observed for the two-electron redox couple [5]2+/1 a, b is in sharp contrast to the C6H6/[C6H6]2− couple, which undergoes only a modest structural deformation., Angewandte Chemie. International Edition, 62 (14), ISSN:1433-7851, ISSN:1521-3773, ISSN:0570-0833

Vat photopolymerization 3D printing provides new opportunities for the fabrication of tissue scaffolds and medical devices. However, for the manufacturing of biodegradable elastomers, it usually requires the use of organic solvents to dissolve the solid photoinitators and achieve low resin viscosity, making this process environmentally unfriendly and not optimal for biomedical applications. Here, we report solvent-free 3D printing of biodegradable elastomers by digital light processing with well-defined photoinitiator–polymer conjugates. Being in liquid state at room temperature, the macrophotoinitiators enabled high-quality 3D printing in the absence of any organic solvents that are usually used in digital light 3D printing. This allowed the systematic investigation of structure–property relationships of 3D-printed biodegradable elastomers without the interference from reactive diluents. The developed macrophotoinitiators were compatible with various photopolymers and could be applied for solvent-free fabrication of biodegradable shape-memory devices. This work offers new perspectives for the solvent-free additive manufacturing of bioresorbable medical implants and other functional devices., Macromolecules, 54 (17), ISSN:1520-5835, ISSN:0024-9297

The replacement of carbon in (C─C)n chains of polyolefins by phosphorus leads to polycarbophosphanes (P─C)n, which may possess unique chemical and physical properties. However, macromolecules with a regular (P─C)n chain have never been unambiguously identified. Here, we demonstrate that addition polymerization, a general concept to polymerize olefins, can be extended to P═C double bonds. The polymerization of monomeric 2-phosphanaphthalenes is mediated by copper(I) halides and leads to polycarbophosphanes with an Mn of 14 to 34 kDa. Each phosphorus is coordinated to Cu(I), which can be easily removed. Unlike long-term durable polyolefins, the metal-free polymers depolymerize rapidly back to monomers under sunlight or ultraviolet irradiation at λ = 365 nm. The monomers can be recycled for repolymerization, demonstrating a cradle-to-cradle life cycle for polycarbophosphanes., Science Advances, 7 (11), ISSN:2375-2548

Inorganic lead halide perovskites have gained immense scientific interest for optoelectronic applications. In this work, we present a one‐dimensional polymorph of cesium lead bromide (δ‐CsPbBr3) synthesized through a simple anion‐exchange reaction, wherein distorted edge‐sharing PbBr6 octahedra form 1D chains isolated by Cs ions. δ‐CsPbBr3 was characterized by Raman spectroscopy, X‐ray diffraction, 207Pb and 133Cs solid‐state NMR, and by optical emission and absorption spectroscopies. This non‐perovskite material irreversibly transforms into the well‐known three‐dimensional perovskite phase (γ‐CsPbBr3) upon heating to above 151 °C. The indirect bandgap was determined by absorption measurements and calculation to be 2.9 eV. δ‐CsPbBr3 exhibits broadband yellow photoluminescence with a quantum yield of 3.2 %±0.2 % at room temperature and 95 %±5 % at 77 K, and this emission is attributed to the recombination of self‐trapped excitons. This study emphasizes that the metastable δ‐CsPbBr3 may be a persistent, concomitant phase in Cs−Pb‐Br‐containing materials systems, such as those used in solar cells and LEDs, and it showcases the characterization tools used for its detection., Helvetica Chimica Acta, 103 (7), ISSN:0018-019X, ISSN:1522-2675

The first β-diketiminato triphosphido diiron complex was synthesized as a versatile molecular single-source precursor for the production of functional FeP that acts as a powerful and durable bifunctional electrocatalyst for water splitting., In large-scale, hydrogen production from water-splitting represents the most promising solution for a clean, recyclable, and low-cost energy source. The realization of viable technological solutions requires suitable efficient electrochemical catalysts with low overpotentials and long-term stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) based on cheap and nontoxic materials. Herein, we present a unique molecular approach to monodispersed, ultra-small, and superiorly active iron phosphide (FeP) electrocatalysts for bifunctional OER, HER, and overall water-splitting. They result from transformation of a molecular iron phosphide precursor, containing a [Fe2P3] core with mixed-valence FeIIFeIII sites bridged by an asymmetric cyclo-P(2+1)3– ligand. The as-synthesized FeP nanoparticles act as long-lasting electrocatalysts for OER and HER with low overpotential and high current densities that render them one of the best-performing electrocatalysts hitherto known. The fabricated alkaline electrolyzer delivered low cell voltage with durability over weeks, representing an attractive catalyst for large-scale water-splitting technologies.

Insertion of a P− anion into a P–P bond yielding the first carborane-substituted 1,2,3-triphospholanide 1 was achieved by treating a carborane-substitued 1,2-diphosphetane with sodium phosphaethynolate. The triphospholanide 1 can serve as a versatile nucleophilic building block for unprecedent functionalised triphospholanes and carborane-substituted polyphosphanes., Chemical Communications, 55 (22), ISSN:1359-7345, ISSN:1364-548X

The first OCP adducts of aluminium and gallium are reported. The complexes are supported by sterically encumbered salen ligands and reveal a selective binding to O and P, respectively. Their reactivity with diazaphosphenium Lewis acids and N-heterocyclic carbene Lewis bases is described, in addition to cycloaddition reactions with s-tetrazines., Dalton Transactions, 48 (13), ISSN:1477-9226, ISSN:1477-9234

The phosphaethynolate anion (OCP)– has three different functions in the reaction with 2,4,6-trimethylbenzoyl chloride (MesCOCl): it acts as a nucleophile, as an en-component in [2 + 2] cycloadditions and as a formal P– transfer reagent., The reaction of Na(OCP) with mesitoyl chloride delivers an ester functionalized 1,2,4-oxadiphosphole in a clean and P-atom economic way. The reaction mechanism has been elucidated by means of detailed NMR-spectroscopic, kinetic and computational studies. The initially formed acyl phosphaketene undergoes a pseudo-coarctate cyclization with an (OCP)– anion under the loss of carbon monoxide to yield a five-membered ring anion. Subsequently, the nucleophilic attack of the formed heterocyclic anion on a second acyl chloride molecule results in the 1,2,4-oxadiphosphole. The transient acyl phosphaketene is conserved during the reaction in the form of four-membered ring adducts, which act as a reservoir. Consequently, the phosphaethynolate anion has three different functions in these reactions: it acts as a nucleophile, as an en-component in [2 + 2] cycloadditions and as a formal P– transfer reagent.

As compared to the normal η1-P σ-complexes or η6-phosphinine π-complexes, the rare μ2-P bridging binding mode of phosphinines can be tuned by employing electron donating substitute., Phosphinines, as aromatic heterocycles, usually engage in coordination as η1-P σ-complexes or η6-phosphinine π-complexes. The μ2-P bridging coordination mode is rarely observed. With the aim to study the effect of different electronic configurations of phosphinines on the coordination modes, a series of anionic phosphinin-2-olates and neutral phosphinin-2-ols were prepared with moderate to high yield. Then the coordination chemistry of these two series was studied in detail towards coinage metals (Au(i) and Cu(i)). It is observed that the anionic phosphinin-2-olates possess a higher tendency to take a bridging position between two metal centers compared to the neutral phosphinin-2-ols. Based on these experimental findings bolstered by DFT calculations, some insight is gained on how the unconventional μ2-P phosphinine bridging coordination mode can be made more conventional and used for the synthesis of polynuclear complexes.

Na(OCP) initiates the catalytic cyclo-trimerization of isocyanates involving the mutual formation of P-heterocycles and spiro phosphoranides (shown on the right) as reactive intermediates., We show that the 2-phosphaethynolate anion, OCP–, is a simple and efficient catalyst for the cyclotrimerization of isocyanates. This process proceeds step-wise and involves five-membered heterocycles, namely 1,4,2-diazaphospholidine-3,5-dionide anions and spiro-phosphoranides as detectable intermediates, both of which were also found to be involved in the catalytic conversion. These species can be considered as adducts of a phosphide anion with two and four isocyanate molecules, respectively, demonstrating that the OCP– anion acts as a formal “P–” source. The interconversion between these anionic species was found to be reversible, allowing them to serve as reservoirs for unique phosphorus-based living-catalysts for isocyanate trimerization.

The reaction of the chloroimidazolium chloride salt, [NHC-Cl][Cl], NHC = C{N(2,6-iPr2C6H3)CH}2 (1) with two equivalents of sodium phosphaethynolate, Na[OCP]·(dioxane)2.5, results in the formation of NHC-{cyclo-(CO)-P2-C(O)} (2) and NHC-P2-C(O)-NHC (3). Notably, in the presence of free NHC ligand, compound 2 converts to compound 3via extrusion of CO at elevated temperatures. The nature of the bonding in these complexes was probed computationally and spectroscopically., Chemical Communications, 53 (91), ISSN:1359-7345, ISSN:1364-548X

A four-coordinate, sixteen-electron Ru(0) complex containing the tetradentate diamino-diolefin ligand (±)-trans-N,N-bis(5H-dibenzo[a,d]cyclohepten-5-yl)-1,2-diaminocyclohexane (trop2dach) has been synthesised. Deprotonation of one amino N–H functional group generates an unprecedented four-coordinate ruthenate species which has been characterised in solution and in the solid state. The newly formed ruthenate complex undergoes intramolecular metal–ligand N–H addition/elimination in solution to generate a transient diamido ruthenium hydride species, as supported by NMR spectroscopy and density functional theory., Chemical Communications, 52 (36), ISSN:1359-7345, ISSN:1364-548X