Ligand Modification Research Articles

Sustained, Selective, and Efficient Photochemical CO2 Reduction to Formate by Electron-Deficient Ruthenium Polypyridyl Complexes.

Metal hydrides play a significant role in a variety of reactions, including chemical, electrochemical, and photochemical CO2 reduction. Molecular metal hydrides have the distinct advantage of allowing tunability of their hydricities by rational ligand modifications, with more electron-rich metal hydrides being in general more hydridic. We report here a new approach to generate highly hydridic metal hydrides of the type [Ru(tpy)(LL)(H)]n+ by introducing electron-withdrawing substituents into the backbone of the bidentate LL ligand. This strategy enables the generation of the metal hydride [Ru(tpy)(LL)(H)]+ at mild negative potentials and further one-electron reduction to the more hydridic [Ru(tpy)(LL)(H)]0 at a potential window that is redox silent for the more electron-rich metal hydride analogue [Ru(tpy)(bpy)(H)]+. In addition, formate release takes place from the hydride transfer adducts [Ru---HCOO)(tpy)(LL)]0 rather than from the corresponding formato complexes [Ru(tpy)(LL)(OCHO)]0, which would require further reduction to [Ru(tpy)(LL)(OCHO)]- as demonstrated by IR spectroelectrochemistry. The parent [Ru(tpy)(LL)(CH3CN)]n+ solvento complexes were then tested as catalysts for the reduction of CO2 to formate in a four-component homogeneous photochemical approach driven by a Ru(II) sensitizer. The results showed selective (>88%) formate production with a record turnover number of ∼50,000 and record turnover frequency of 4.4 s-1 when compared to other molecular catalysts.

Nanoparticles modified with glucose analogs to enhance the permeability of the blood-brain barrier and their accumulation in the epileptic brain.

Drug delivery for epilepsy treatment faces enormous challenges, where the sole focus on enhancing the ability of drugs to penetrate the blood-brain barrier (BBB) through ligand modification is insufficient because of the absence of seizure-specific drug accumulation. In this study, an amphipathic drug carrier with a glucose transporter (GLUT)-targeting capability was synthesised by conjugating 2-deoxy-2-amino-D-glucose (2-DG) to the model carrier DSPE-PEG2k. A 2-DG-modified nano drug delivery system (NDDS) possessing robust stability and favourable biocompatibility was then fabricated using the nanoprecipitation method. The results showed that the 2-DG-modified NDDS exhibited enhanced cellular uptake by brain capillary endothelial cells and neuronal cells. Most importantly, the 2-DG-modified NDDS exhibited enhanced BBB penetration and brain accumulation, especially in the epileptic brain, thus achieving seizure-based on-demand drug delivery. Our study provides a simple and smart strategy for the delivery of anti-seizure medicines.

Frontispiz: Orientational Compatibility Modulation of Ligands in Low‐Symmetry Multi‐Cavity Discrete Coordination Cages by Neighbouring Cage Participation

Frontispiz: Orientational Compatibility Modulation of Ligands in Low‐Symmetry Multi‐Cavity Discrete Coordination Cages by Neighbouring Cage Participation

Frontispiece: Orientational Compatibility Modulation of Ligands in Low‐Symmetry Multi‐Cavity Discrete Coordination Cages by Neighbouring Cage Participation

Frontispiece: Orientational Compatibility Modulation of Ligands in Low‐Symmetry Multi‐Cavity Discrete Coordination Cages by Neighbouring Cage Participation

Homogeneously Blended Donor and Acceptor AgBiS2 Nanocrystal Inks Enable High‐Performance Eco‐Friendly Solar Cells with Enhanced Carrier Diffusion Length

AbstractColloidal semiconductor nanocrystals (NCs) have garnered significant attention as promising photovoltaic materials due to their tunable optoelectronic properties enabled by surface chemistry. Among them, AgBiS2 NCs stand out as an attractive candidate for solar cell applications due to their environmentally friendly composition, high absorption coefficients, and low‐temperature processability. However, AgBiS2 NC photovoltaics generally exhibit lower power conversion efficiency (PCE) compared to other NC‐based devices, primarily due to numerous surface traps that serve as recombination sites, leading to a short diffusion length for free carriers. To address this challenge, this work develops donor and acceptor blended (D/A) AgBiS2 films. Through ligand modulation, this work formulates acceptor and donor AgBiS2 NC inks with suitable electrical band alignment for charge separation, while ensuring that they are fully miscible in the same solvent. This enabled the fabrication of high‐quality, thickness‐controllable D/A‐blended junction films. This work finds that this approach effectively facilitates carrier separation, leading to an enhanced carrier lifetime and diffusion length. As a result, using this approach, this work achieves AgBiS2 films that are twice as thick in solar cell applications compared to conventional devices, leading to improvements in current density and a solar cell PCE of 8.26%.

Targeted delivery of polymeric NO-donor micelles to hepatic stellate cells for restoration of liver function and inhibition of hepatic fibrosis.

Liver fibrosis is a prevalent liver disease associated with significant morbidity, and the activation of hepatic stellate cells (HSCs) serves as the primary causative factor driving the progression of liver fibrosis. However, capillarization of liver sinusoidal endothelial cells (LSECs) induced by hepatic fibrosis can reduce nitric oxide (NO) production and bioavailability, which consequently loses the ability to retain HSCs dormant, leading to amplified HSCs activation. Herein, an elaborate micelle (VN-M@BN) loaded with benazepril (BN) was constructed by self-assembly of polymeric NO donor, aiming for the controlled release of NO in liver fibrosis lesions thereby impeding the progression of liver fibrosis. VN-M@BN with the vitamin A (VA) ligand modification was designed to target HSCs for efficient liver fibrosis inhibition. Controlled NO release significantly downregulated α-smooth muscle actin (α-SMA) and induced apoptosis of activated HSCs, thus enhancing the inhibition effects of BN towards HSCs. Furthermore, the in suit antifibrotic treatment results confirmed that VN-M@BN possessed good circulatory stability and targetability to liver fibrotic tissues, thereby effectively ameliorating the collagen deposition and fibrosis process in damaged liver tissues. The NO-based targeted nanodrug system enabled precise delivery of therapeutic drugs to activated HSCs, thereby synergizing the efficacy in treating liver fibrosis with minimal adverse effects.

DNA Tetrahedron-Driven Multivalent Proteolysis-Targeting Chimeras: Enhancing Protein Degradation Efficiency and Tumor Targeting.

Proteolysis-targeting chimeras (PROTACs) are dual-functional molecules composed of a protein of interest (POI) ligand and an E3 ligase ligand connected by a linker, which can recruit POI and E3 ligases simultaneously, thereby inducing the degradation of POI and showing great potential in disease treatment. A challenge in developing PROTACs is the design of linkers and the modification of ligands to establish a multifunctional platform that enhances degradation efficiency and antitumor activity. As a programmable and modifiable nanomaterial, DNA tetrahedron can precisely assemble and selectively recognize molecules and flexibly adjust the distance between molecules, making them ideal linkers. Herein, we developed a multivalent PROTAC based on a DNA tetrahedron, named AS-TD2-PRO. Using DNA tetrahedron as a linker, we combined modules targeting tumor cells, recognizing E3 ligases, and multiple POI together. We took the undruggable target protein signal transducer and activator of transcription 3 (STAT3), associated with the etiology and progression in a variety of malignant tumors, as an example in this study. AS-TD2-PRO with two STAT3 recognition modules demonstrated good potential in enhancing tumor-specific targeting and degradation efficiency compared to traditional bivalent PROTACs. Furthermore, in a mouse tumor model, the superior therapeutic activity of AS-TD2-PRO was observed. Overall, DNA tetrahedron-driven multivalent PROTACs both serve as a proof of principle for multifunctional PROTAC design and introduce a promising avenue for cancer treatment strategies.

Tumor Microenvironment Responsive Key Nanomicelles for Effective Against Invasion and Metastasis in Ovarian Cancer Using Mice Model.

Ovarian cancer is difficult to detect in its early stages, and it has a high potential for invasion and metastasis, along with a high rate of recurrence. These factors contribute to the poor prognosis and reduced survival times for patients with this disease. The effectiveness of conventional chemoradiotherapy remains limited. Nano-particles, as a novel drug delivery system, have significant potential for improving therapeutic efficacy and overcoming these challenges. According to the high expression level of matrix metalloproteinase-2 (MMP-2) in the tumor microenvironment, MMP-2 responsive nano-particles (PVGLIG-MTX-D/T-NMs) containing docetaxel and triptolide were prepared by the thin-film dispersion method. The synergistic effect between docetaxel and triptolide was systematically investigated, the ratio of the two drugs was optimized, and the physicochemical properties of the nano-particles and their ability to inhibit ovarian cancer cell growth and metastasis were evaluated in vitro and in vivo. PVGLIG-MTX-D/T-NMs enhanced the targeting, stability, and bioavailability of the drug, while reducing the dose and toxicity. In addition, by regulating the expression levels of E-Cadherin, N-Cadherin, matrix metalloproteinases (MMPs), hypoxia-inducible factor 1-alpha (HIF-1α), and vascular endothelial growth factor (VEGF), it exhibited an inhibitory effect on epithelial-mesenchymal transformation (EMT) and tumor cell angiogenesis, and effectively inhibited the invasion and metastasis of ovarian cancer cells. PVGLIG-MTX-D/T-NMs achieved passive targeting of tumor sites by enhancing permeability and retention (EPR) effects. Subsequently, the uptake of the drug by tumor cells was enhanced by MMP-2 responsiveness and the modification of methotrexate targeting ligands. By regulating the expression levels of invasion- and metastasis-related proteins in tumor tissues, the nano-particles affected the EMT process, inhibited tumor angiogenesis, and suppressed the malignant potential of invasion and metastasis in ovarian cancer. These findings provided a new direction for further exploration of tumor-targeted therapy.

Exploring the structural evolution of Cu-thiolate nanoclusters and their property correlations.

Research on copper nanoclusters (Cu NCs) is expanding rapidly due to their remarkable structural versatility and related tunable properties they exhibit. This fast-paced development creates a need for a comprehensive overview of the structural evolution of Cu NCs, especially regarding how different geometric configurations emerge from variations in the ligand choice. In light of this, this feature article focuses on the role of thiolate ligands in shaping the structural and electronic properties of Cu NCs, with a particular emphasis on how modifications of ligands influence the geometry of NCs. While thiolates play a central role in stabilizing Cu NCs, this feature article also underscores the significance of co-ligands-such as hydrides, phosphines, and halides-because relying solely on thiolates is often insufficient to fully protect the surface of Cu NCs, unlike in the case of gold or silver NCs. A detailed analysis of how various thiolates and co-ligands affect core geometry reveals a direct correlation with the electronic properties of Cu NCs, which in turn influences their optical behavior. By examining these ligand-driven structural and electronic changes, this feature article aims to provide a deeper understanding of the relationship between ligand design and the resulting NC properties. The ultimate goal is to offer a strategy for the rational design of Cu NCs with tailored functionalities, thereby advancing NC chemistry and opening up new possibilities for applications in optoelectronics, catalysis, and sensing.

Exploring the luminescent and thermometric potentials of samarium(III) diketonate complexes with extended fluoroalkyl chains.

We synthesized and investigated a new series of Sm3+ 1,3-diketonate complexes with CnF2n+1-homologous thiophene-containing ligands. A clear correlation was found between the number of fluorine atoms in the 1,3-diketone's carbon chain and the luminescent properties of the samarium(III) complexes. The ligand modification method employed facilitates targeted and significant enhancements in the photoluminescence quantum yield (PLQY). Notably, the PLQY value peaked at 5.2% for the complex with n = 4 before decreasing with longer chains, a trend contrasting with that observed for Eu and Nd complexes. Temperature-dependent shifts in the CIE coordinates were observed, making these compounds suitable as luminescent thermometers with a sensitivity of 2.2% K-1 and resolution of 0.2 K at 120 K.

Alkyl PCCP ligands for chromium-catalyzed ethylene tri-/tetramerization: Strong impact of subtle ligand modification on their performance

Alkyl PCCP ligands for chromium-catalyzed ethylene tri-/tetramerization: Strong impact of subtle ligand modification on their performance

Enhancing photovoltaic performance of graphene quantum dot/Ru(II) nanocomposites through strategic ligand modifications

Enhancing photovoltaic performance of graphene quantum dot/Ru(II) nanocomposites through strategic ligand modifications

Organometallic Photocatalyst-Promoted Synthesis and Modification of Carbohydrates under Photoirradiation.

Carbohydrates are natural, renewable, chemical compounds that play crucial roles in biological systems. Thus, efficient and stereoselective glycosylation is an urgent task for the preparation of pure and structurally well-defined carbohydrates. Photoredox catalysis has emerged as a powerful tool in carbohydrate chemistry, providing an alternative for addressing some of the challenges of glycochemistry. Over the last few decades, Ir- and Ru-based organometallic photocatalysts have attracted significant interest because of their high stability, high-energy triplet state, strong visible-light absorption, long luminescence lifetime, and amenability to ligand modification. This review highlights the recent progress in the organometallic photocatalyst-promoted synthesis and modification of carbohydrates under photoirradiation, as well as the related benefits and drawbacks.

Research progress in polysaccharide-modified lipid nanoparticles for drug delivery

Lipid nanoparticles serve as a promising drug delivery system due to the good biocompatibility, non-immunogenicity, and high drug loading efficiency. However, unmodified lipid nanoparticles have limitations such as poor stability, easy hydrolysis, and rapid removal. To overcome these shortcomings, researchers have developed peptide modification, antibody modification, ligand modification, nucleic acid aptamer modification, and polysaccharide modification for lipid nanoparticles. Polysaccharides are a class of natural polymers, and the polysaccharide-modified lipid nanoparticles exhibit good biocompatibility, precise targeting, and low toxicity. Therefore, polysaccharide-modified lipid nanoparticles demonstrate great potential in clinical treatment. This review summarizes the preparation and application of polysaccharide-modified lipid nanoparticles, aiming to provide a reference for further research and development of new lipid nanoparticles.

Adjacent-Ligand Tuning of Atomically Precise Cu-Pd Sites Enables Efficient Methanol Electrooxidation with a CO-Free Pathway.

Whether the catalyst can realize the non-CO pathway is the key to greatly improve the catalytic activity and stability of methanol oxidation reaction (MOR). It is feasible to optimize the reaction path selectivity by modifying organic ligands and constructing single-atom systems. At the same time, heterogeneous metal nanosheets with atomic thickness have been shown to significantly enhance the catalytic activity of materials due to their ultra-high exposure of active sites and synergistic effects. Herein, we synthesize an ultra-thin heterogeneous alloy metallene with organic ligand-modified surface Cu single atom by one-pot wet chemical method, and further construct an efficient Cu-Pd active sites. The prepared octanoic acid ligand modified PdCu single-atom alloys metallene (SAA OA-Cu-Pdene) shows excellent catalytic activity and stability, with mass activity up to 5.64 A mgPd -1 and electrochemical active surface area (ECSA) up to 160.39 m2 gPd -1. Structural characterization and in situ experiment jointly indicate that ligand modulation brings about charge transfer, and the accompanying rapid migration of OH- greatly improves the selectivity of non-CO pathways while improving the catalytic activity. The results highlight the importance of adjacent-ligand regulation and provide a new strategy for the design of MOR catalysts with high selectivity of non-CO pathway.

Predicting Magnetic Barriers in Lanthanide Complexes with Electrostatic Potential Charges.

Single-molecule magnets (SMMs) with slow relaxation of magnetization and blocking temperatures above that of liquid nitrogen are essential for practical applications in high-density data storage devices and quantum computers. A rapid and accurate prediction of the effective magnetic relaxation barrier (Ueff) is needed to accelerate the discovery of high-performance SMMs. Using density functional theory and multireference calculations, we explored correlations between Ueff, partial atomic charges, and the anisotropic barrier for a series of sandwich-type lanthanide complexes containing cyclooctatetraene, substituted cyclopentadiene, phospholyl, boratabenzene, or borane ligands. Our results show a correlation between the electrostatic potential charge of the lanthanide ion in the complex and Ueff. Systematic ligand modifications show that reducing ligand nucleophilicity and incorporating soft bases enhance magnetic anisotropy and Ueff values. This work identifies a correlation to predict Ueff values and optimization of ligand coordination environments in lanthanide-based SMMs.

The Effects of Ligands with Different Electron Donation on the Nitrogen Reduction Performance of Constructed Co-MOFs: NH3 or N2H4?

Four cobalt-based metal-organic frameworks (Co-MOFs) based on different ligands with varying electron-donating properties (dpt = 2,5-di(pyridin-4-yl)-1,3,4-thiadiazole, NH₂bdc = 5-aminoisophthalic acid, OHbdc = 5-hydroxyisophthalic acid, H₂tdc = thiophene-2,5-dicarboxylic acid, and hfipbb = 4,4'-(hexafluoropropane-2,2-diyl)bisbenzoic acid) are synthesized. Among them, Co-dpt-NH₂bdc demonstrates the highest nitrogen reduction reaction activity, achieving an ammonia (NH3) yield of 68.61 µg·h⁻¹·mgcat⁻¹ and Faraday efficiency (FE) of 6.75 %. The enhanced performance is attributed to stronger electronic interactions and improved charge transfer capabilities facilitated by the electron-donating properties of NH₂bdc. Additionally, Co-dpt-NH₂bdc can produce hydrazine (N₂H₄), achieving N₂H₄ yield of 90.62 µg·h⁻¹·mgcat⁻¹ and FE of 65.67 %, as a byproduct caused from the interaction between the generated NH₃ and the amino group on the NH₂bdc ligand. This work highlights the potential of molecular engineering in tuning the electronic states of catalytic sites to enhance electrocatalytic activity and provides insights into the production of N₂H₄ through ligand modulation.

Recent Advances in Tetra-Coordinate Boron-Based Photoactive Molecules for Luminescent Sensing, Imaging, and Anticounterfeiting.

Tetra-coordinate boron-based fluorescent materials hold considerable promise across chemistry, biology and materials science due to their unique and precisely tunable optoelectronic properties. The incorporation of the heteroatom boron (B) enables these materials to exhibit high luminescence quantum yields, adjustable absorption and emission wavelengths, and exceptional photostability. This review examines the molecular design and applications of tetra-coordinate boron-based photoactive molecules, highlighting their roles in fluorescence sensing, anticounterfeiting, and imaging. We outline how structural features impact their properties and discuss strategies for enhancing their performance, including ligand modification and the extension of conjugation length, among others. Additionally, future research focus in this field is also addressed including strategies for diversifying molecular structures and enhancing molecular stability, which is believed to pave the way for innovative solutions to the challenges in areas such as sensing, imaging and information security.

Modeling Ligand Binding Site Water Networks with Site Identification by Ligand Competitive Saturation: Impact on Ligand Binding Orientations and Relative Binding Affinities.

Appropriate treatment of water contributions to protein-ligand interactions is a very challenging problem in the context of adequately determining the number of waters to investigate and undertaking conformational sampling of the ligands, the waters, and the surrounding protein. In the present study, an extension of the Site Identification by Ligand Competitive Saturation-Monte Carlo (SILCS-MC) docking approach is presented that enables the determination of the location of water molecules in the binding pocket and their impact on the predicted ligand binding orientation and affinities. The approach, termed SILCS-WATER, involves MC sampling of the ligand along with explicit water molecules in a binding site followed by selection of a subset of waters within specified energetic and distance cutoffs that contribute to ligand binding and orientation. To allow for convergence of both the water and ligand orientations, SILCS-WATER is based on just the overlap of the ligand and water with the SILCS FragMaps and the interaction energy between the waters and ligand. Results show that the SILCS-WATER methodology can capture important waters and improve ligand binding orientations. For 6 of 10 multiple ligand-protein systems, the method improved relative binding affinity prediction against experimental results, with substantial improvements in five systems, when compared to standard SILCS-MC. Improved reproduction of crystallographic ligand binding orientations is shown to be an indicator of when SILCS-WATER will yield improved binding affinity correlations. The method also identifies waters interacting with ligands that occupy unfavorable locations with respect to the protein whose displacement through the appropriate ligand modifications should improve ligand binding affinity. Results are consistent with the binding affinity being modeled as a ligand-water complex interacting with the protein. The presented approach offers new possibilities in revealing water networks and their contributions to the binding orientation and affinity of a ligand for a protein and is anticipated to be of utility for computer-aided drug design.

High-performance electromagnetic absorbing Ni/C composites derived from Ni-MOF materials: Effects of organic ligands and pyrolysis temperatures

Magnetic carbon-based materials derived from nickel organic framework (Ni-MOF) are considered to be a kind of electromagnetic wave (EMW) absorbing materials with great potential and application value. However, the precise design of Ni-MOF-derived magnetic carbon-based materials remains a huge challenge. In the present work, through the modulation of organic ligand and pyrolysis temperature, Ni/C composites with excellent electromagnetic absorption properties are obtained due to their improved multiple loss and optimized impedance matching. Specifically, the organic ligand and pyrolysis temperature affect the degree of graphitization of the carbon frame and the specific surface area of the Ni/C composites, thus changing the conductivity, magnetic properties and electromagnetic parameters. In particular, the sample Ni/C-2-500 using H2BPDC as the organic ligand and calcined at 500 °C gives an RLmin of −50.37 dB and an EAB of 6.0 GHz at a packing rate of 30 wt% and a thickness of 2.5 mm, which covers the entire Ku band. In addition, Ni/C-2-500 exhibits good thermal conductivity. Therefore, this study provides an idea for exploring MOF materials and their derivatives with tunable EMW absorbing properties and heat conduction advantages prepared by different organic ligands.