The present study reports that non-van der Waals 2D materials, hematene and magnetene, show very efficient optical limiting (OL) from UV to visible, with their optical limiting onset (OL_on) values exhibiting a decreasing trend towards UV irradiation wavelengths. The obtained results render these materials very promising candidates for OL-related applications, such as the protection of human retinal from high-power laser.

Abstract

Recently, the preparation of some hematene and magnetene ultrathin non van der Waals (non-vdW) 2D nanoplatelets was reported starting from hematite and magnetite natural iron ores. The present work reports on the determination and evaluation of the nonlinear optical response and the optical limiting (OL) action of these 2D nanoplatelets dispersed in water under ns laser excitation. The obtained results show that both hematene and magnetene exhibit strong nonlinear absorption and refraction, comparable and even larger than those of other van der Waals (vdW) 2D counterpart materials. In addition, due to their strong nonlinear absorption, both hematene and magnetene show exceptional OL performance from the UV to visible, attaining very low values of optical limiting onset (OL_on), comparable and even lower than that of vdW 2D nanomaterials, such as graphene, graphene oxide, other transition metal dichalcogenides like MoS₂, WS₂ and MoSe₂, black phosphorous and antimonene. Moreover, hematene was found to exhibit more efficient OL action than magnetene for all the excitation wavelengths studied, attributed to more efficient ligand to metal charge transfer. The present findings open new possibilities for the potential use of these non-vdW 2D materials in photonics and optoelectronics, e. g., as optical limiters and optical switchers.

A versatile synthetic approach towards supramolecularly programmed monomers that can form discrete macrocyclic species of controllable size and shape through amidinium-carboxylate interactions in both apolar and polar media is described.

Abstract

We describe herein the optimized design and modular synthetic approach towards supramolecularly programmed monomers that can form discrete macrocyclic species of controllable size and shape through amidinium-carboxylate interactions in apolar and polar media.

Herein, different dimensions of Cs₂AgCl₃ (1D) and CsAgCl₂ (2D) metal halides have been synthesized in different solvents, DMF and DMSO, respectively. By comparing the functional group, dielectric constant, and donor number among four solvents (DMF, DMSO, DMAC, DMPU), we find the donor number plays the predominant role in the dimension tuning.

Abstract

Dimension growth of metal halides is important for its properties and applications. However, such dimension control of the metal halides is rarely reported in the literature and the growth mechanism is not clear yet. A minute difference of solvent properties can tremendously alter the process of nucleation and growth of crystals. Herein, an intriguing phenomenon of dimension tuning for Ag-based metal halides is reported. The 1D Cs₂AgCl₃ crystals can be obtained in pure DMF while the 2D CsAgCl₂ crystals are obtained in pure DMSO. Both exhibit bright yellow emission, which are derived from self-trapping excitons (STEs). The photoluminescence quantum yield (PLQY) of Cs₂AgCl₃ (1D) and CsAgCl₂ (2D) are 28.46 % and 20.61 %, respectively. In order to understand the mechanism of the dimension change, additional solvents (N,N-dimethylacetamide, DMAC, 1,3-Dimethyl-Tetrahydropyrimidin-2(1H)-one, DMPU) are also selected to process the precursor for crystal growth. By comparing the functional group, dielectric constant, and donor number among the four solvents, we find the donor number plays the predominant role in nucleation process for Cs₂AgCl₃ and CsAgCl₂. This research reveals the relationship between coordination ability of the solvent and the dimension of metal halides.

Chemical synthesis of two common core human milk oligosaccharides—para-lacto-N-hexaose (pLNH) and para-lacto-N-neohexaose (pLNnH)—using a convergent 3+3 approach has been reported.

Abstract

Human milk oligosaccharides (HMO) have emerged as a very active area of research in glycoscience and nutrition. HMO are involved in the early development of infants and may help to prevent certain diseases. The development of chemical methods for obtaining individual HMO aids the global effort dedicated to understanding the roles of these biomolecules. Reported herein is the chemical synthesis of two common core hexasaccharides found in human milk, i. e. para-lacto-N-hexaose (pLNH) and para-lacto-N-neohexaose (pLNnH). After screening multiple leaving groups and temporary protecting group combinations, a 3+3 convergent coupling strategy was found to work best for obtaining these linear glycans.

If NHC-stabilized borenium ions [NHC−BH₂]⁺ and [PF₆]⁻ take the same bus, they will get off neutralized and with a noticeable change, i. e., as NHC−BF₃ and PH₂F₃. However, if tetrakis(perfluoro-tert-butoxy)aluminate is the second passenger, the anion remains untouched and a bis(boronium) or a bis(borenium) ion can enjoy the journey.

Abstract

The dinuclear bis(N-heterocyclic carbene) borane adduct 2 rapidly reacts with tritylium salts at room temperature but the outcome is strongly impacted by the respective counter-ion. Using tritylium tetrakis(perfluoro-tert-butoxy)aluminate affords – depending on the solvent – either the bis(boronium) ion 4 or the hydride-bridged dication 5. In case of tritylium hexafluorophosphate, however, H/F exchange occurs between boron and phosphorus yielding the dinuclear BF₃ adduct 3 along with phosphorus dihydride trifluoride. H/F exchange also takes place when using the mononuclear N-heterocyclic carbene BH₃ adduct 6 and hence provides a facile route to PH₂F₃, which is usually synthesized in more complex reaction sequences regularly involving toxic hydrogen fluoride. DFT calculations shed light on the H/F exchange between the borenium ion and the [PF₆]⁻ counter-ion and the computed mechanism features only small barriers in line with the experimental observations.

High throughput screening was used to rapidly identify a new crystalline porous salt (CPOS). Using flow chemistry, the CPOS was scaled, and the material was shown to have permeant porosity with a carbon dioxide uptake of 4.3 mmol/g at 195 K, making it one of the most porous and scalable CPOS reported to date.

Abstract

Crystalline porous organic salts (CPOS) are a subclass of molecular crystals. The low solubility of CPOS and their building blocks limits the choice of crystallisation solvents to water or polar alcohols, hindering the isolation, scale-up, and scope of the porous material. In this work, high throughput screening was used to expand the solvent scope, resulting in the identification of a new porous salt, CPOS-7, formed from tetrakis(4-sulfophenyl)methane (TSPM) and tetrakis(4-aminophenyl)methane (TAPM). CPOS-7 does not form with standard solvents for CPOS, rather a hydrated phase (Hydrate2920) previously reported is isolated. Initial attempts to translate the crystallisation to batch led to challenges with loss of crystallinity and Hydrate2920 forming favorably in the presence of excess water. Using acetic acid as a dehydrating agent hindered formation of Hydrate2920 and furthermore allowed for direct conversion to CPOS-7. To allow for direct formation of CPOS-7 in high crystallinity flow chemistry was used for the first time to circumvent the issues found in batch. CPOS-7 and Hydrate2920 were shown to have promise for water and CO₂ capture, with CPOS-7 having a CO₂ uptake of 4.3 mmol/g at 195 K, making it one of the most porous CPOS reported to date.

Nickel complexes with a N-heterocyclic carbene ligand (TIMEN ^iPr) have been synthesized and characterized. Starting from the Ni⁰ precursor, a Ni^II hydride is synthesized that reacts with protons to form a rare Ni−H₂ intermediate, which was studied by NMR spectroscopy and DFT calculations. Further reduction closes the synthetic cycle.

Abstract

Dihydrogen evolution was observed in a two-step protonation reaction starting from a Ni⁰ precursor with a tripodal N-heterocyclic carbene (NHC) ligand. Upon the first protonation, a Ni^II monohydride complex was formed, which was isolated and fully characterized. Subsequent protonation yields H₂ via a transient intermediate (INT) and an isolable Ni^II acetonitrile complex. The latter can be reduced to regenerate its Ni⁰ precursor. The mechanism of H₂ formation was investigated by using a deuterated acid and scrutinized by ¹H NMR spectroscopy and gas chromatography. Remarkably, the second protonation forms a rare nickel dihydrogen complex, which was detected and identified in solution and characterized by ¹H NMR spectroscopy. DFT-based computational analyses were employed to propose a reaction profile and a molecular structure of the Ni−H₂ complex. Thus, a dihydrogen-evolving, closed-synthetic cycle is reported with a rare Ni−H₂ species as a key intermediate.

Direct C-H methylation is a highly valuable approach for introducing methyl groups into organic molecules, particularly in pharmaceutical chemistry. Among the various methodologies available, photo-induced methylation stands out as an exceptional choice due to its mild reaction conditions, energy efficiency, and compatibility with functional groups. This article offers a comprehensive review of photochemical strategies employed for the direct and selective methylation of C(sp3)-H, C(sp2)-H, and C(sp)-H bonds in various organic molecules. The discussed methodologies encompass transition metal-based photocatalysis, organophotocatalysis, as well as other metal-free approaches, including electron donor-acceptor (EDA)-enabled transformations. Importantly, a wide range of easily accessible agents such as tert-butyl peroxide, methanol, DMSO, acetic acid, methyl halides, and even methane can serve as effective methylating reagents for modifying diverse targets. These advancements in photochemical C-H methylation are anticipated to drive further progress in the fields of organic synthesis, photocatalysis, and pharmaceutical development, opening up exciting avenues for creating novel organic molecules and discovering new drug compounds.

Ongoing advances in CuII-catalyzed aerobic oxidative coupling reactions between arylboronic esters and diverse heteroatom nucleophiles have strengthened the development of the general Chan-Lam (CL) based reaction protocol, including the C−O bond formation methodologies. In-depth mechanistic understanding of CL etherification with specific emphasize on different reaction routes and its energetics are still lacking, even though the reaction has been experimentally explored. Here, we present a DFT-guided computational study to unravel the mechanistic pathways of the CL-based etherification reaction. The computational findings provide some interesting insights on the fundamental steps of the catalytic cycle, particularly the rate-determining transmetalation event. Aryl boronic ester coordinated, methoxide bridged CuII intermediate acts as resting state, which undergoes transmetalation accompanying an activation barrier of 20.4 kcal/mol. The energy spans of the remaining fundamental steps leading to the methoxylated product are relatively low. The minor product requires an additional 14.2 kcal/mol energy span to surmount in comparison to the favored route. Hammett studies for the substituted aryl boronic esters reveal higher reaction turnover for electron-rich aryl systems. The results agree with the previously reported spectroscopic and kinetic observations. For a series of alcohol substrates, it was observed that except for cyclohexanol, moderate to high etherification turnovers are predicted.

Poly(glycerol) functionalized detonation nanodiamonds conjugated with boron-10 cluster and active targeting moiety were designed and synthesized. The nanodrugs were taken up by tumor cells and exhibited boron neutron capture therapy (BNCT) efficacy upon thermal neutron irradiation.

Abstract

Boron neutron capture therapy (BNCT), advanced cancer treatment utilizing nuclear fission of ¹⁰B atom in cancer cells, is attracting increasing attention. As ¹⁰B delivery agent, sodium borocaptate (¹⁰BSH, ¹⁰B₁₂H₁₁SH ⋅ 2Na), has been used in clinical studies along with L-boronophenylalanine. Recently, this boron cluster has been conjugated with lipids, polymers or nanoparticles to increase selectivity to and retentivity in tumor. In this work, anticancer nanoformulations for BNCT are designed, consisting of poly(glycerol) functionalized detonation nanodiamonds (DND−PG) as a hydrophilic nanocarrier, the boron cluster moiety (¹⁰B₁₂H₁₁ ²⁻) as a dense boron-10 source, and phenylboronic acid or RGD peptide as an active targeting moiety. Some hydroxy groups in PG were oxidized to carboxy groups (DND−PG−COOH) to conjugate the active targeting moiety. Some hydroxy groups in DND−PG−COOH were then transformed to azide to conjugate ¹⁰B₁₂H₁₁ ²⁻ through click chemistry. The nanodrugs were evaluated in vitro using B16 murine melanoma cells in terms of cell viability, BNCT efficacy and cellular uptake. As a result, the ¹⁰B₁₂H₁₁ ²⁻ moiety is found to facilitate cellular uptake probably due to its negative charge. Upon thermal neutron irradiation, the nanodrugs with ¹⁰B₁₂H₁₁ ²⁻ moiety exhibited good anticancer efficacies with slight differences with and without targeting moiety.