Boron neutron capture therapy (BNCT) is a promising modality for cancer treatment because of its minimal invasiveness. To maximize the therapeutic benefits of BNCT, the development of efficient platforms for the delivery of boron agents is indispensable. Here, we prepared carborane-integrated immunoliposomes via an exchanging reaction to achieve HER-2-targeted BNCT. The conjugation of an anti-HER-2 antibody to carborane-integrated liposomes successfully endowed these liposome with targeting properties toward HER-2-overexpressing human ovarian cancer cells (SK-OV3); the resulting BNCT activity toward SK-OV3 cells obtained using the current immunoliposomal system was 14-fold that of the l-BPA/fructose complex, which is a clinically available boron agent. Moreover, the growth of spheroids treated with our system followed by thermal neutron irradiation was significantly suppressed compared with treatment with the l-BPA/fructose complex.

Lithium-rich layered oxides (LLOs, Li1.2Mn0.54Ni0.13Co0.13O2) are widely used as cathode materials for lithium-ion batteries due to its high specific capacity, high operating voltage and low cost. However, the LLOs are faced with rapid decay of charge/discharge capacity and voltage, as well as interface side reactions, which limit its electrochemical performance. Herein, the dual strategies of sulfite/sodium ion co-doping and lithium carbonate coating were used to improve it. It founds that modified LLOs achieve 88.74% initial coulomb efficiency, 295.3 mAh g–1 first turn discharge capacity, in addition to 216.9 mAh g–1 at 1 C, and 87.23% capacity retention after 100 cycles. Mechanism research indicated that the excellent electrochemical performance benefits from the doping of both Na+ and SO32-, and it could significantly reduce the migration energy barrier of Li+ and promote Li+ migration. Meanwhile, anion and cation are co-doped greatly reduces the band gap of LLOs and increase its electrical conductivity, and no electron spin barrier leap effect at the Fermi level. In addition, the lithium carbonate coating significantly inhibits the occurrence of interfacial side reactions of LLOs. This work provides a theoretical basis and practical guidance for the further development of LLOs with higher electrochemical performance.

Overcrowded bistricyclic aromatic enes (BAEs) have several conformations such as twisted and anti-folded conformers, and their stereochemistry and chromism have been studied in earnest. In this study, we synthesized boron-containing heteromerous BAEs having various tricyclic structures and investigated their photophysical properties. Single-crystal X-ray analysis revealed that the introduction of a rigid fluorene unit resulted in a twisted conformer, whereas the introduction of flexible units such as thioxanthene and 9,9-dimethyl-9,10-dihydroanthracene units resulted in an anti-folded conformer. The absorption spectra of the heteromerous BAEs were dependent on the introduced tricyclic structures, suggesting the immense impact of the tricyclic structures on the electronic structures of BAEs. DFT calculations revealed the large effect of the flexibility of the tricyclic structures on the thermodynamic stability of the conformers. In addition, the boron-containing heteromerous BAEs underwent photocyclization reactions, indicating their potential application as precursors of polyaromatic hydrocarbons and helical aromatic materials.

Group I alkoxides and amylates efficiently catalyze the heterodehydrocoupling of challenging silane and amine substrates under mild conditions! This represents one of the most straightforward and accessible methods to form aminosilanes through heterodehydrocoupling! This train is now leaving the station – don't miss it!

Abstract

Group I alkoxides are highly active precatalysts in the heterodehydrocoupling of silanes and amines to afford aminosilane products. The broadly soluble and commercially available KO ^t Amyl was utilized as the benchmark precatalyst for this transformation. Challenging substrates such as anilines were found to readily couple primary, secondary, and tertiary silanes in high conversions (>90 %) after only 2 h at 40 °C. Traditionally challenging silanes such as Ph₃SiH were also easily coupled to simple primary and secondary amines under mild conditions, with reactivity that rivals many rare earth and transition-metal catalysts for this transformation. Preliminary evidence suggests the formation of hypercoordinated intermediates, but radicals were detected under catalytic conditions, indicating a mechanism that is rare for Si−N bond formation.

Hexadecylamine capped Pd-Zn nanoparticles were realized by a combination of solvated metal atom dispersion and co-digestive approaches. Acetylene semi-hydrogenation was achieved using Pd−Zn nanoparticles at room temperature and atmospheric pressure with high selectivity towards ethylene.

Abstract

A reaction of fundamental and commercial importance is acetylene semi-hydrogenation. Acetylene impurity in the ethylene feedstock used in the polyethylene industry poisons the Ziegler-Natta catalyst which adversely affects the polymer quality. Pd based catalysts are most often employed for converting acetylene into the main reactant, ethylene, however, it often involves a tradeoff between the conversion and the selectivity and generally requires high temperatures. In this work, bimetallic Pd−Zn nanoparticles capped by hexadecylamine (HDA) have been synthesized by co-digestive ripening of Pd and Zn nanoparticles and studied for semi-hydrogenation of acetylene. The catalyst showed a high selectivity of ~85 % towards ethylene with a high ethylene productivity to the tune of ~4341 μmol g⁻¹ min⁻¹, at room temperature and atmospheric pressure. It also exhibited excellent stability with ethylene selectivity remaining greater than 85 % even after 70 h on stream. To the best of the authors’ knowledge, this is the first report of room temperature acetylene semi-hydrogenation, with the catalyst effecting high amount of acetylene conversion to ethylene retaining excellent selectivity and stability among all the reported catalysts thus far. DFT calculations show that the disordered Pd−Zn nanocatalyst prepared by a low temperature route exhibits a change in the d-band center of Pd and Zn which in turn enhances the selectivity towards ethylene. TPD, XPS and a range of catalysis experiments provided in-depth insights into the reaction mechanism, indicating the key role of particle size, surface area, Pd−Zn interactions, and the capping agent.

First atomistic-level study of organic single component and cocrystalline materials upon exposure to gamma radiation. EPR and periodic DFT calculations delineated how noncovalent interactions provide a crucial role in the structural stability of these materials upon exposure to radiation.

Abstract

Developing an atomistic understanding of ionizing radiation induced changes to organic materials is necessary for intentional design of greener and more sustainable materials for radiation shielding and detection. Cocrystals are promising for these purposes, but a detailed understanding of how the specific intermolecular interactions within the lattice upon exposure to radiation affect the structural stability of the organic crystalline material is unknown. This study evaluates atomistic-level effects of γ radiation on both single- and multicomponent organic crystalline materials and how specific noncovalent interactions and packing within the crystalline lattice enhance structural stability. Dose studies were performed on all crystalline systems and evaluated via experimental and computational methods. Changes in crystallinity were evaluated by p-XRD and free radical formation was analyzed via EPR spectroscopy. Type of intermolecular interactions and packing within the crystal lattice was delineated and related to the specific free radical species formed and the structural integrity of each material. Periodic DFT and HOMO-LUMO surface mapping calculations provided atomistic-level identifications of the most probable sites for the radicals formed upon exposure to γ radiation and relate intermolecular interactions and molecular packing within the crystalline lattice to experimental results.

Two mixed-valence diiron complexes with carbon bridges are reported. The mixed-valence [2Fe−2C] complex 4 possesses a low-spin ground state yet displays strong valence delocalization as evident by Mössbauer spectroscopy. In contrast, the reduced [2Fe−C] complex 5 displays a class-III valence-delocalized ground state that is supported by magnetometry, vis-NIR and Mössbauer spectroscopy, as well as DFT calculations.

Abstract

The carbide ligand in the iron–molybdenum cofactor (FeMoco) in nitrogenase bridges iron atoms in different oxidation states, yet it is difficult to discern its ability to mediate magnetic exchange interactions due to the structural complexity of the cofactor. Here, we describe two mixed-valent diiron complexes with C-based ketenylidene bridging ligands, and compare the carbon bridges with the more familiar sulfur bridges. The ground state of the [Fe₂(μ-CCO)₂]⁺ complex with two carbon bridges (4) is S= , and it is valence delocalized on the Mössbauer timescale with a small thermal barrier for electron hopping that stems from the low Fe−C force constant. In contrast, one-electron reduction of the [Fe₂(μ-CCO)] complex with one carbon bridge (2) affords a mixed-valence species with a high-spin ground state (S= ), and the Fe−Fe distance contracts by 1 Å. Spectroscopic, magnetic, and computational studies of the latter reveal an Fe−Fe bonding interaction that leads to complete valence delocalization. Analysis of near-IR intervalence charge transfer transitions in 5 indicates a very large double exchange constant (B) in the range of 780–965 cm⁻¹. These results show that carbon bridges are extremely effective at stabilizing valence delocalized ground states in mixed-valent iron dimers.

An efficient continuous flow O-nitration of aliphatic polyols was developed. Industrially important nitrate esters containing two, three and four nitro groups were synthesized. Examples include glycol dinitrates: 1,2-propanediol dinitrate (PGDN), ethylene glycol dinitrate (EGDN), diethylene glycol dinitrate (DEGDN), triethylene glycol dinitrate (TEGDN); trinitrates: trimethylolethane trinitrate (TMETN), 1,2,4-butanetriol trinitrate (BTTN); and tetranitrates: erythritol tetranitrate (ETN). The optimized process for each molecule provided yield >90 % in a short residence time of 1 min corresponding to a space time yield of >18 g/h/mL reactor volume.

Abstract

Nitrate esters are important organic compounds having wide application in energetic materials, medicines and fuel additives. They are synthesized through nitration of aliphatic polyols. But the process safety challenges associated with nitration reaction makes the production process complicated and economically unviable. Herein, we have developed a continuous flow process wherein polyol and nitric acid are reacted in a microreactor to produce nitrate ester continuously. Our developed process is inherently safer and efficient. The process was optimized for industrially important nitrate esters containing two, three and four nitro groups. Substrates include glycol dinitrates: 1,2-propylene glycol dinitrate (PGDN), ethylene glycol dinitrate (EGDN), diethylene glycol dinitrate (DEGDN), triethylene glycol dinitrate (TEGDN); trinitrates: trimethylolethane trinitrate (TMETN), 1,2,4-butanetriol trinitrate (BTTN); and tetranitrates: erythritol tetranitrate (ETN). The optimized process for each molecule provided yield >90 % in a short residence time of 1 min corresponding to a space time yield of >18 g/h/mL of reactor volume.

The functionalisation of carbon nanotubes has been instrumental in broadening its application field, allowing especially its use in biological studies. Although numerous covalent and non-covalent functionalisation methods have been described, the characterisation of the final materials has always been an added challenge. Among the various techniques available, Raman spectroscopy is one of the most widely used to determine the covalent functionalisation of these species. However, Raman spectroscopy is not a quantitative technique, and no studies are reported comparing its performance when the same number of functional groups are added but using completely different reactions. In this work, we have experimentally and theoretically studied the functionalisation of carbon nanotubes using two of the most commonly used reactions: 1,3-dipolar cycloaddition of azomethylene ylides and diazonium-based radical addition. The number of groups introduced onto the tubes by these reactions has been determined by different characterisation techniques. The results of this study support the idea that data obtained by Raman spectra are only helpful for comparing functionalisations produced using the same type of reaction. However, they should be carefully analysed when comparing functionalisations produced using different reaction types.

The reaction of 9-diazo-9H-fluorene (fluN2) with the potassium aluminyl K[Al(NON)] ([NON]2– = [O(SiMe2NDipp)2]2–, Dipp = 2,6-iPr2C6H3) affords K[Al(NON)(κN1,N3-{(fluN2)2})] (1). Structural analysis shows a near planar 1,4-di(9H-fluoren-9ylidene)tetraazadiide ligand that chelates to the aluminium. The thermally induced elimination of dinitrogen from 1 affords the neutral aluminium ketimide complex, Al(NON)(N=flu)(THF) (2) and the 1,2di(9H-fluoren-9-yl)diazene dianion as the potassium salt, [K2(THF)3][fluN=Nflu] (3). The reaction of 2 with N,N'diisopropylcarbodiimide (iPrN=C=NiPr) affords the aluminium guanidinate complex, Al(NON){N(iPr)C(N=CMe2)N(CHflu)} (4), showing a rare example of reactivity at a metal ketimide ligand. Density functional theory (DFT) calculations have been used to examine the bonding in the newly formed [(fluN2)2]2– ligand in 1 and the ketimide bonding in 2. The mechanism leading to the formation of 4 has also been studied using this technique.