Carboxy to methyl reduction is an important transformation in organic synthesis, yet existing methodologies often require multi-step procedures or use hazardous metal hydrides. Herein, a metal-free catalytic system is reported for the one-step reduction of esters, carboxylic acids, and carbamates to a methyl group, in the presence of catalytic amounts of boronic acids. By using ammonia borane as a hydrogen donor, a wide range of products bearing different functional groups can be obtained in high yields under relatively mild conditions. Mechanistic studies and control experiments elucidate the complexity of the mechanism and provide an explanation for the observed selectivity.
Optimization of 3D synthetic scaffolds for neuronal tissue engineering applications
The increasing prevalence of neurodegenerative diseases has spurred researchers to develop advanced 3D models that accurately mimic neural tissues. Hydrogels stand out as ideal candidates as their properties closely resemble those of the extracellular matrix. A critical challenge in this regard is to comprehend the influence of the scaffold's mechanical properties on cell growth and differentiation, thus enabling targeted modifications. In light of this, a synthesis and comprehensive analysis of acrylamide-based hydrogels incorporating a peptide has been conducted. Adequate cell adhesion and development is achieved due to their bioactive nature and specific interactions with cellular receptors. The integration of a precisely controlled physicochemical hydrogel matrix and inclusion of the arginine-glycine-aspartic acid peptide sequence has endowed this system with an optimal structure, thus providing a unique ability to interact effectively with biomolecules. The analysis fully examined essential properties governing cell behavior, including pore size, mechanical characteristics, and swelling ability. Cell-viability experiments were performed to assess the hydrogel’s biocompatibility, while the incorporation of grow factors aimed to promote the differentiation of neuroblastoma cells. The results underscore the hydrogel’s ability to stimulate cell viability and differentiation in the presence of the peptide within the matrix.
Reticular Synthesis of Flexible Rare‐Earth Metal‐Organic Frameworks: Control of Structural Dynamics and Sorption Properties Through Ligand Functionalization
An exciting direction in metal-organic frameworks involves the design and synthesis of flexible structures which can reversibly adapt their structure when triggered by external stimuli. Controlling the extent and nature of response in such solids is critical in order to develop custom dynamic materials for advanced applications. Towards this, it is highly important to expand the diversity of existing flexible MOFs, generating novel materials and gain an in-depth understanding of the associated dynamic phenomena, eventually unlocking key structure-property relationships. In the present work, we successfully utilized reticular chemistry for the construction of two novel series of highly crystalline, flexible rare-earth MOFs, RE-thc-MOF-2 and RE-teb-MOF-1. Extensive single-crystal to single-crystal structural analyses coupled with detailed gas and vapor sorption studies, shed light onto the unique responsive behavior. The development of these series is related to the reported RE-thc-MOF-1 solids which were found to display a unique continuous breathing and gas-trapping property. The synthesis of RE-thc-MOF-2 and RE-teb-MOF-1 materials represents an important milestone as they provide important insights into the key factors that control the responsive properties of this fascinating family of flexible materials and demonstrates that it is possible to control their dynamic behavior and the associated gas and vapor sorption properties.
Umpolung Reactivity of Diazo Arylidene Succinimides: Distal C–H Functionalization of α‐Thiocarbonyls from the Reactive Carbenoid Center
Herein, for the first time we have explored the umpolung reactivity of vinylogous carbon center of diazo arylidene succinimide (DAS) through rhodium catalysis to achieve [2,3]-Stevens rearrangement of α-thioether esters. The protocol has successfully demonstrated the distal C-H bond functionalization of the α-thioether esters. Alongside, the carbenoid reactivity of DAS has also been achieved with Doyle-Kirmse reaction of allyl/propargyl phenyl sulfides. The protocol proved to be practical to synthesize a wide variety of [2,3]-Stevens rearrangement products exclusively and the possible side products emanating from Pummerer rearrangement and [1,2]-Stevens rearrangement were not observed. This catalytic protocol works smoothly in environmentally benign solvent under open air to afford the corresponding desired products with excellent diastereo-, regio- and chemo-selectivities in good to excellent yields. The protocol also proved to be scalable on gram quantity.
Magnetic Peroxidase Nanozyme Gears Up for Microplastic Removal and Deconstruction
The highlight features a recently reported approach of integrating magnetic properties of bare Fe3O4 nanoparticles and nanozyme technology for the removal and degradation of microplastics with nearly 100 % efficiency.
Abstract
Plastic is an important commodity that is used in several sectors. However, plastic waste generation is a pressing issue and needs attention as it risks the environment. While methods such as landfilling, incineration and recycling are known for handling plastic waste, they have their own limitations like generation of secondary pollutants and the low quality of the recycled plastic. In this scenario, new methods and technologies for efficiently handling plastic waste are the need of the hour as it is aggravating the concern of pollution and its health risks. This highlight article predominantly focuses on the recently reported combinatorial approach (Angew. Chem. Int. Ed. 2022, 61, e202212013), where it has been shown that integrating the magnetic property of bare Fe3O4 nanoparticles and nanozyme technology can be used for microplastic removal and degradation with nearly 100 % efficiency.
Development and Use of a Real‐time In‐situ Monitoring Tool for Electrochemical Advanced Oxidation Processes
The development of an apparatus for real-time in-situ monitoring of electrochemical advanced oxidation processes using visible spectrophotometry is reported. The approach uses commercially available equipment and a 3-D printable interface. It is used to monitor the anodic oxidation of Acid Orange 7, probing the impact of varying electrode composition, current density, electrolyte concentration, and stirring speed on the rate of decolorization.
Abstract
An apparatus for real-time in-situ monitoring of electrochemical advanced oxidation processes using visible spectrophotometry has been developed. Central to the design is a 3D-printed sleeve that interfaces commercially available electrochemical and spectrophotometry units. Using the anodic oxidation of Acid Orange 7 as a test bed, the apparatus has been used for probing the impact of varying electrode composition, current density, electrolyte concentration, and stirring speed on the rate of decolorization. In addition, the unit was used to prove that decolorization can continue after electrolysis has been stopped, thereby showing the inherent value of real-time monitoring. Given that a significant challenge in the field of advanced oxidation processes is the inability to compare different reported systems, our approach, using commercially available equipment and a printable interface may open avenues for more standardized data collection.
Cover Picture: (Chem. Methods 10/2023)
Steric Influence on the Constitution of Beryllium Phosphine Complexes
The threshold cone angle of phosphines was determined, below which two ligands can be accommodated in the first ligand sphere of beryllium dihalide fragments. While [(PMe2Ph)2BeX 2] (X=Cl, Br, I) and [(PMePh2)2BeX 2] are mononuclear complexes, [(PPh3)BeX 2]2 is dinuclear and exhibits dynamic behaviour in solution due to phosphine dissociation. This high dynamicity is the reason for halide exchange with dichloromethane.
Abstract
The phosphine complexes of beryllium chloride, bromide and iodide, [(PMe2Ph)2BeX 2], [(PMePh2)2BeX 2] and [(PPh3)BeX 2]2 (X=Cl, Br, I) were prepared and characterised with multinuclear NMR spectroscopy. Additionally the molecular structure of dinuclear [(PPh3)BeCl2]2 was determined with single crystal X-ray diffraction techniques. The threshold cone angle of the phosphines, below which two ligands can coordinate to the beryllium dihalide fragments, is between 136° and 145°. Halide-chloride exchange in dichloromethane is observed for [(PPh3)BeBr2]2 and [(PPh3)BeI2]2, which leads to the formation of [(PPh3)BeCl2]2. Due to the relatively low Lewis basicity of PPh3, it almost exclusively acts as a spectator ligand with only little formation of phosphonium cations.
An Imidazolylidene‐Based Mesoionic Carbene–Mn(I) Complex and Its Catalytic Potential in N‐Heteroarene Hydrogenation
A novel imidazolylidene backbone-based mesoionic carbene (MIC)−Mn(I) complex Mn-bim-MICimz is developed and explored in N-heteroarene hydrogenation process.
Abstract
Herein we report the first mesoionic carbene (MIC)-Mn(I) complex Mn-bim-MICimz derived from imidazolylidene motif. Structurally the octahedral Mn(I) complex Mn-bim-MICimz was assembled with an anionic benzimidazolato-anchored imidazolylidene MIC-based bidentate ligand (bim-MICimz ) and four CO ligands, as supported by detailed characterization using NMR and FTIR spectroscopy, mass spectrometry, and single crystal X-ray diffraction study. We reckoned that the bim-MICimz ligand would provide a robust and stable bonding with the Mn(I) centre, and also enhance electron density at the Mn(I) centre through its stronger σ-donating/weaker π-accepting property. These structural and electronic attributes triggered to exploit Mn-bim-MICimz in catalytic hydrogenation of N-heteroarenes, where efficient hydride (Mn−H) delivery is a key step.
Front Cover: Steric Influence on the Constitution of Beryllium Phosphine Complexes (Eur. J. Inorg. Chem. 29/2023)
The Front Cover shows the art gallery within the Beryllium Centre, which exhibits some of the latest samples of beryllium art. The current exhibition features the solid state structure of dinuclear [(PPh3)BeCl2]2. In this piece, only one phosphine ligand can be accommodated due to the steric bulk of PPh3. However, two smaller ligands, like PMePh2, can find a place in the Beryllium Centre. Therefore, size restrictions apply with a threshold cone angle from 136° to 145°. This parameter dictates whether single or double admission is allowed. Furthermore, the electron donating abilities of the ligands determine whether they behave as spectator ligands or attack the solvent. Therefore, the walls are covered with advertising flyers by the stronger donors. More information can be found in the Research Article by M. R. Buchner and S. I. Ivlev.