Binary and Halide-free Catalyst Systems Based on Al/Ga/In Aminopyridylbisphenolate Complexes for the Cycloaddition of Epoxides and CO.

Group 13 complexes bearing an aminopyridylbisphenol ligand have been prepared [; L = ligand, M = Al (X = Cl and Br), Ga (X = Cl, Br, and I), or In (X = Cl)]. The structures of the complexes containing the chloride ligand (; M = Al, Ga, and In) have been directly compared through an X-ray crystallography study, with differences in the monomeric or dimeric nature of their structures observed. All of the complexes obtained have been studied as potential catalysts for the synthesis of cyclic carbonates from epoxides and CO.

Copolymerization of β-Butyrolactones into Functionalized Polyhydroxyalkanoates Using Aluminum Catalysts: Influence of the Initiator in the Ring-Opening Polymerization Mechanism.

Within bioplastics, natural poly(3-hydroxybutyrate) (PHB) stands out as fully biocompatible and biodegradable, even in marine environments; however, its high isotacticity and crystallinity limits its mechanical properties and hence its applications. PHB can also be synthesized with different tacticities via a catalytic ring-opening polymerization (ROP) of rac-β-butyrolactone (BBL), paving the way to PHB with better thermomechanical and processability properties. In this work, the catalyst family is extended based on aluminum phenoxy-imine methyl catalyst [AlMeL], that reveals efficient in the ROP of BBL, to the halogeno analogous complex [AlClL].

Correction to "N-Heterocyclic Carbene-Carbodiimide (NHC-CDI) Betaines as Organocatalysts for β-Butyrolactone Polymerization: Synthesis of Green PHB Plasticizers with Tailored Molecular Weights".

[This corrects the article DOI: 10.1021/acscatal.3c05357.

Alkali metal⋯methyl short contacts in aluminates: more than agostic interactions.

Knowing the nature and strength of noncovalent interactions is key to enhancing the synthetic methods and catalytic processes in which they are involved. We present herein the synthesis and characterization of a novel aluminium sodium oximate compound, followed by a comprehensive computational study of the sodium⋯methyl interaction that appears in its crystal structure. Our experimental results have been compared to a large set of structural data retrieved from the Cambridge Structural Database in order to assess the main geometrical preferences of these interactions.

Synthesis and applications of the sulfur containing analogues of cyclic carbonates.

Cyclic thiocarbonates are the sulfur containing analogues of the well-studied cyclic carbonates and are relatively poorly explored despite their potential applications and intriguing reactivities. To date, application of these organosulfur compounds has included their use as monomers for polythiocarbonate synthesis (their ring-opening is more readily achieved and more selective than the corresponding cyclic carbonates) and as reactive intermediates for the preparation of a range of higher-value sulfur containing compounds. Despite these uses, the synthesis of these compounds is far less explored and developed than their non-sulfur analogues.

Pyridine-4-thiol as halogen-bond (HaB) acceptor: influence of the noncovalent interaction in its reactivity.

The study of pyridine-4-thiol as a halogen-bond (HaB) acceptor has allowed the isolation of its cocrystal with the HaB donor ICFI, namely, 1,2,4,5-tetrafluoro-3,6-diiodobenzene bis(pyridin-1-ium-4-ylsulfanide), CFI·2CHNS (1), where the S atom is the HaB acceptor, while the pyridine position is blocked by the proton. Furthermore, the S atom acts a dual acceptor and also establishes an interaction with the pyridinium proton from an adjacent molecule. The presence of these interactions in 1 contributes to the stabilization of the zwitterionic form.

Group 13 salphen compounds (In, Ga and Al): a comparison of their structural features and activities as catalysts for cyclic carbonate synthesis.

Many complexes based on group 13 elements have been successfully applied as catalysts for the synthesis of cyclic carbonates from epoxides and CO and to date these have provided some of the most active catalysts developed. It is notable that most reports have focused on the use of aluminium-based compounds likely because of the well-established Lewis acidity of this element and its cost. In comparison, relatively little attention has been paid to the development of catalysts based on the heavier group 13 elements, despite their known Lewis acidic properties.

σ-Hole triel bonds in aluminium derivatives.

This communication reports the synthesis and X-ray characterization of a new mononuclear aluminium compound exhibiting an intramolecular σ-hole triel bonding interaction. It is compared with a dinuclear aluminium compound, previously reported by us, where the aluminium atoms participate in two concurrent σ-hole triel bonding interactions. To our knowledge, such behaviour has not been previously described in the literature.

Chemoselective cycloadditions to epoxide derivatives of erucic acid with CO and CS: controlled access to value-added bio-derived compounds.

The potential for application of bio-derived molecules in our everyday lives is attracting vast interest as attention moves towards development of a truly circular and sustainable economy. Whilst a large number of molecules are naturally available and contain a variety of functional groups, few of these compounds are able to be immediately transferred to applications where they can directly replace established oil-derived species. This issue presents both a challenge and an opportunity for the synthetic chemistry community.

Ring-Opening Polymerization of -Lactide Catalyzed by Potassium-Based Complexes: Mechanistic Studies.

Two non-toxic potassium compounds, and , with a commercial oximate ligand have been prepared and fully spectroscopically characterized. Their activity as catalysts for the ring-opening polymerization (ROP) process of LLA has been studied, showing that they are extremely active and able to polymerize the monomer in a few minutes. For derivative , the presence of a crown ether in the potassium coordination sphere affects the nuclearity of the compound and consequently its solubility, with both aspects having an influence in the polymerization process.

Abrogation of Notch Signaling in Embryonic TECs Impacts Postnatal mTEC Homeostasis and Thymic Involution.

Notch signaling is crucial for fate specification and maturation of thymus-seeding progenitors along the T-cell lineage. Recent studies have extended the role of Notch signaling to thymic epithelial cells (TECs), showing that Notch regulates TEC progenitor maintenance and emergence of medullary TECs (mTECs) in fetal thymopoiesis. Based on immunohistochemistry studies of spatiotemporal regulation of Notch activation in the postnatal thymus, we show that Notch activation is not confined to fetal TECs.

Rheology of Poly(glycidyl methacrylate) Macromolecular Nano Assemblies.

A recently reported combined polymerization process of glycidyl methacrylate, mediated by homometallic and heterobimetallic aluminium complexes, naturally produces nano-sized macromolecular assemblies. In this work, the morphological features and the rheological properties of these novel nanoassemblies are studied. The hydrodynamic sizes of the nanoparticles in the solution range from 10 to 40 nm (in numbers), but on a flat surface they adopt a characteristic thin disk shape.

NHC-CDI Betaine Adducts and Their Cationic Derivatives as Catalyst Precursors for Dichloromethane Valorization.

Zwitterionic adducts of N-heterocyclic carbene and carbodiimide (NHC-CDI) are an emerging class of organic compounds with promising properties for applications in various fields. Herein, we report the use of the ICyCDI(-Tol) betaine adduct () and its cationic derivatives and as catalyst precursors for the dichloromethane valorization via transformation into high added value products CHZ (Z = OR, SR or NR). This process implies selective chloride substitution of dichloromethane by a range of nucleophiles NaZ (preformed or generated from HZ and an inorganic base) to yield formaldehyde-derived acetals, dithioacetals, or aminals with full selectivity.

Conjugated polymer nanostructures displaying highly photoactivated antimicrobial and antibiofilm functionalities.

This work reports the use of conjugated polymer nanostructures (CPNs) as photoactivated antimicrobial compounds against Gram-positive and Gram-negative microorganisms. Two representative CPNs of polythiophene (PEDOT) and polyaniline (PANI) were prepared as nanofibres with an average diameter of 40 nm and length in the micrometer range. Both CPNs exhibited strong antimicrobial activity under UVA irradiation with the same fluence rate as the UVA component of the solar spectrum.

Poly(glycidyl methacrylate) macromolecular assemblies as biocompatible nanocarrier for the antimicrobial lysozyme.

The antimicrobial lysozyme (Lys) was electrostatically incorporated to negatively charged crosslinked poly(glycidyl methacrylate) (c-PGMA) macromolecular assemblies. The resulting material was characterized by AFM, infrared spectra, water contact angle measurements and the staining with the primary amino specific dye fluorescamine. c-PGMA nanoparticles were successfully loaded with Lys reaching ratios of 27.

Conducting Polymer-Based Nanohybrids for Fuel Cell Application.

Carbon materials such as carbon graphitic structures, carbon nanotubes, and graphene nanosheets are extensively used as supports for electrocatalysts in fuel cells. Alternatively, conducting polymers displayed ultrahigh electrical conductivity and high chemical stability havegenerated an intense research interest as catalysts support for polymer electrolyte membrane fuel cells (PEMFCs) as well as microbial fuel cells (MFCs). Moreover, metal or metal oxides catalysts can be immobilized on the pure polymer or the functionalized polymer surface to generate conducting polymer-based nanohybrids (CPNHs) with improved catalytic performance and stability.

Polymeric ruthenium precursor as a photoactivated antimicrobial agent.

Ruthenium coordination compounds have demonstrated a promising anticancer and antibacterial activity, but their poor water solubility and low stability under physiological conditions may limit their therapeutic applications. Physical encapsulation or covalent conjugation with polymers may overcome these drawbacks, but generally involve multistep reactions and purification processes. In this work, the antibacterial activity of the polymeric precursor dicarbonyldichlororuthenium (II) [Ru(CO)Cl] has been studied against Escherichia coli and Staphylococcus aureus.

IL-7R is essential for leukemia-initiating cell activity of T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy resulting from the dysregulation of signaling pathways that control intrathymic T-cell development. Relapse rates are still significant, and prognosis is particularly bleak for relapsed patients. Therefore, development of novel therapies specifically targeting pathways controlling leukemia-initiating cell (LIC) activity is mandatory for fighting refractory T-ALL.

Heterobimetallic aluminate derivatives with bulky phenoxide ligands: a catalyst for selective vinyl polymerization.

New aluminium-alkali metal heterometallic compounds using the bulky ligand OAr = 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide have been synthesized and characterized. The species obtained, [MAlMe3(OAr)] (M = Li(2a), Na(2b), K(2c)) and [MAlMe2(OAr)2] (M = Li(3a), Na(3b), K(3c)), include some of the few heterobimetallic examples of aluminate complexes with O-donor ligands described so far. Their activity in polymerization towards a difunctional monomer, such as Glycidyl Methacrylate (GMA), was evaluated.

Aluminates with Fluorinated Schiff Bases: Influence of the Alkali Metal⁻Fluorine Interactions in Structure Stabilization.

New heterometallic aluminium-alkali metal compounds have been prepared using Schiff bases with electron withdrawing substituents as ligands. The synthesis of these new species was achieved via the reaction of AlMe₃ with the freshly prepared alkali-metallated ligand. The derivatives formed were characterized by NMR in solution and by single crystal X-ray diffraction in the solid state.

Interaction of an imidazolium-2-amidinate (NHC-CDI) zwitterion with zinc dichloride in dichloromethane: role as ligands and C-Cl activation promoters.

Adducts of imidazolium carbenes and carbodiimides (NHC-CDI) are emerging as a new class of thermally stable and modular zwitterions with many potential applications. Our study of the interaction of a representative NHC-CDI zwitterion with ZnCl in dichloromethane led to the serendipitous discovery of a highly selective, double activation of dichloromethane C-Cl bonds.

The NOTCH1/CD44 axis drives pathogenesis in a T cell acute lymphoblastic leukemia model.

NOTCH1 is a prevalent signaling pathway in T cell acute lymphoblastic leukemia (T-ALL), but crucial NOTCH1 downstream signals and target genes contributing to T-ALL pathogenesis cannot be retrospectively analyzed in patients and thus remain ill defined. This information is clinically relevant, as initiating lesions that lead to cell transformation and leukemia-initiating cell (LIC) activity are promising therapeutic targets against the major hurdle of T-ALL relapse. Here, we describe the generation in vivo of a human T cell leukemia that recapitulates T-ALL in patients, which arises de novo in immunodeficient mice reconstituted with human hematopoietic progenitors ectopically expressing active NOTCH1.

Schiff-base -ate derivatives with main group metals: generation of a tripodal aluminate metalloligand.

New heterobimetallic aluminates with well-defined structures bearing bidentate Schiff bases as ligands have been prepared. The ligands studied are PhO-CH[double bond, length as m-dash]N-Ar (Ar = C6H5 (La) and 2,6-iPr-C6H3 (Lb)), with and without donor substituents in the ortho position of the arene ring bonded to the iminic nitrogen. To prepare the heterometallic species, the HL proligands were treated with the appropriate alkali metal precursor and then AlMe3 was added.