Modification Of Chains Research Articles

Linear and branched alkyl chain modification of PF resin: Synthesis, pyrolysis and ablative performance at high heat flux

Alkyl modified phenolic resins were synthesized by acid catalyzed etherification of Phenol formaldehyde resin (PF) using linear (n-propyl-NPA and n-butyl-NBA) and branched (iso-propyl-IPA and t-butyl-TBA) chain alcohols and characterized. Spectroscopic characterization (FTIR and 1H NMR) and hydroxyl value revealed the extent of etherification to be ca. 10-13%. Enthalpy of curing was not significantly varied with etherification from the control PF resin. Mechanical property evaluation indicated an increase in elongation by 60-80 %. Glass transition temperature was about 135-144 °C vis- a- vis 148 °C for the unmodified PF resin. Thermal stability of the synthesized PF resins was not significantly altered and a marginal improvement in char residue (PF- 49 % and alkyl modified PF- 54 -57 %) was observed at 900 °C. Low density carbon composites (0.70 g/cc) were processed using these PF resins as matrix resins and porous graphitic felt as reinforcement and evaluated their thermal and ablative characteristics. Alkyl modification improved the wettability of the graphitic felt and a reduction in backwall temperature was observed when the cured composites were subjected to Plasma arc jet at 220 W/cm2 at the end of 500 seconds.

Synthesis and biological evaluation of lappaconitine analogues as potential anti-neuroinflammatory agents by side chain modification and scaffold hopping strategy

Neuroinflammation mediated by microglia is widely recognized as a key pathophysiological mechanism in neurodegenerative diseases. Lappaconitine (LA) is a natural C18-diterpenoid alkaloid isolated from Aconitum sinomontanum Nakai, and previous study showed that LA and its derivatives inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 cells. However, the anti-neuroinflammatory effects of LA and its derivatives on microglia are still not clear. Here, LA analogues were designed and synthesized, and the anti-neuroinflammatory activity of the synthesized compounds was screened using LPS-induced overexpression of NO in BV-2 microglia. The screening results showed that compound 10 displayed the highest ability to inhibit NO production (IC50 = 9.98 ± 1.6 µM). Mechanistic investigations revealed that compound 10 attenuated LPS-activated neuroinflammation through suppression of TLR4/MyD88/NF-κB pathway in BV-2 microglia. Acute toxicity assays showed that compound 10 (LD50 = 508.1 mg/kg) was safer relative to LA (LD50 = 30.6 mg/kg). Collectively, our findings show that compound 10 could have potential as anti-neuroinflammatory agents.

When more sugar is better-a GPI side chain modification results in a less virulent phenotype during a protozoan infection.

The assembly and function of side chain modifications of glycosylphosphatidylinositol (GPI) units (anchors or free forms) are poorly defined. In a recent study, two enzymes, PIGJ and PIGE, of the protozoan parasite Toxoplasma gondii were identified and shown to be involved in the assembly of such GPI side chains (J. A. Alvarez, E. Gas-Pascual, S. Malhi, J. C. Sánchez-Arcila, et al., mBio 15:e00527-24, 2024, https://doi.org/10.1128/mbio.00527-24). PIGJ adds N-acetylgalactosamine to the GPI core structure, while PIGE subsequently adds a terminal glucose. Deletion of PIGJ resulted in the loss of the side chain and, strikingly, increased mortality in infected mice, in contrast to PIGE knockouts. Absence of the side chain led to increased binding of the scavenger receptor CD36 to mutant parasites. In galectin-3 knockout mice, the virulent phenotype of side-chain-deficient parasites was largely lost. While the exact mechanisms remain to be elucidated by more experiments, these findings provide the first evidence for the importance of GPI side chains in parasite-host interactions in vivo.

Structural analysis of gum arabic side chains from Acacia seyal released by bifidobacterial β-arabino-oligosaccharide 3-O-β-l-arabinopyranosyl-α-l-arabinofuranosidase

Gum arabic is widely used in the food and beverage industries for its emulsifying, stabilizing, and prebiotic effects, which promote Bifidobacterium growth. The two commercially approved varieties of gum arabic, namely, Acacia senegal gum and A. seyal gum, predominantly consist of arabinogalactan protein (AGP), albeit with different side chain modifications. We previously characterized two enzymes belonging to glycoside hydrolase (GH) family 39 in bifidobacteria involved in the release of α-d-Gal-(1→3)-α-l-Ara and β-l-Arap-(1→3)-α-l-Ara from the side chains of A. senegal gum. Although the carbohydrate structure of A. senegal gum is being increasingly explored, limited information is available on A. seyal gum. In this study, we discovered a novel GH39 β-arabino-oligosaccharide 3-O-β-l-arabinopyranosyl-α-l-arabinofuranosidase from Bifidobacterium catenulatum and revealed the accurate structure of β-l-arabino-oligosaccharides released from A. seyal gum as [β-l-Araf-(1→2)-]n-β-l-Arap-(1→3)-α-l-Araf-(1→) (n = 0–3). Growth assays and intracellular enzyme activity assessments using B. catenulatum revealed that β-l-arabino-oligosaccharides were degraded to l-arabinose by GH127 β-l-arabinofuranosidase and GH36 β-l-arabinopyranosidase. This study provides new insights into the diversity of AGP structures and the utilization mechanisms of A. seyal gum in bifidobacteria.

The essence and characteristics of global value chains: theoretical aspect

The article carries out a comparative analysis of scientific approaches to understanding the essence of global value chains, as a result of which the author’s position on this issue is substantiated. It has been established that the territorial organization of international business and the international division of labor form the conceptual basis of the formation of global value chains. Special attention is paid to how processes of global economic integration contribute to constant modifications of value chains, as well as the importance of their effective management, which is a decisive factor in increasing the competitiveness of companies and countries. The article argues that participation in global value chains provides businesses and governments with significant benefits, such as access to new markets, increased production efficiency, and increased value added. At the same time, risks have been identified, in particular those related to the instability of supply chains, increased competition and dependence on global markets. Different types of global value chains and features of their management in the conditions of modern challenges of globalization are considered. Conclusions have been made regarding the prospects for the development of Ukrainian business based on the concept of global value chains, taking into account global trends and national features of the economy. The article is useful for scientists, specialists in the field of international business and economics, as well as for those who are interested in the integration of national economies into global production processes. A comparative analysis of the positions of modern scientists regarding the essence of global value chains was carried out. Reasoned author’s position on the issue of the essence of global value chains. It has been established that the territorial organization of international business, as well as the international division of labor, is the conceptual basis for the formation of global value chains. It is argued that in the conditions of strengthening integration processes in the global economy, constant modifications of global value chains take place, and their management becomes one of the important factors of competitiveness. The benefits that business units and countries receive from participating in global value chains are determined, and the associated risks are also identified. The typology of global value chains, features of their management are analyzed. Conclusions have been made regarding the prospects for domestic business development based on the concept of global value chains.

Modifications of the respiratory chain of Bacillus licheniformis as an alkalophilic and cyanide-degrading microorganism

Bacillus licheniformis can use cyanide as a nitrogen source for its growth. However, it can also carry out aerobic respiration in the presence of this compound, a classic inhibitor of mammalian cytochrome c oxidase, indicating that B. licheniformis has a branched respiratory chain with various terminal oxidases. Here, we studied the modifications in the respiratory chain of B. licheniformis when cells were cultured in Nutrient Broth, an alkaline medium with ammonium, or an alkaline medium with cyanide. Then, we measured oxygen consumption in intact cells and membranes, enzyme activities, carried out 1D and 2D-BN-PAGE, followed by mass spectrometry analysis of BN-PAGE bands associated with NADH, NADPH, and succinate dehydrogenase activities. We found that cell growth was favored in a nutrient medium than in an alkaline medium with cyanide. In parallel, respiratory activity progressively decreased in cells cultured in the rich medium, alkaline medium with ammonium, and the lowest activity was in the cells growing in the alkaline medium with cyanide. B. licheniformis membranes contain NADH, NADPH, and succinate dehydrogenases, and the proteomic analysis detected the nitrate reductase and the bc, caa3, aa3, and bd complexes. The succinate dehydrogenase migrated with a molecular mass of 375 kDa, indicating its association with the nitrate reductase (115 kDa + 241 kDa, respectively). The NADH dehydrogenase of B. licheniformis forms aggregates of different molecular mass.

Diphtheria Toxoid-Derived T-Helper Epitope and α-galactosylceramide Synergistically Enhance the Immunogenicity of Glycopeptide Antigen.

The tumor-associated antigen MUC1 is an attractive target for immunotherapy, however, its weak immunogenicity limits the induction of antitumor immune responses. To overcome this limitation, in this study, MUC1 glycopeptide was covalently linked with a diphtheria toxin-derived T-helper epitope (DT331-345). Subsequently, the resulting DT-MUC1 glycopeptide was physically mixed with natural killer T cell agonist αGalCer to explore their immunomodulatory synergy. Biological results demonstrated that compared to MUC1+αGalCer and DT-MUC1 groups, the specific IgG antibody titer of DT-MUC1+αGalCer group increased by 189- and 3-fold, respectively, indicating that the diphtheria toxin-derived T-helper epitope synergistically enhanced MUC1 immunogenicity with αGalCer. Moreover, the DT-MUC1+αGalCer vaccine induced potent cellular immune responses and significantly inhibited the growth of B16-MUC1 tumors in vivo. Furthermore, it was found that the anti-MUC1 IgG antibody titer induced by DT-MUC1+αGalCer was equivalent to that induced by palmitoylated DT-MUC1+αGalCer (P1-DT-MUC1+αGalCer) and significantly higher than that induced by doubly palmitoylated DT-MUC1+αGalCer (P2-DT-MUC1+αGalCer), suggesting that the easily synthesized DT-MUC1 may not require lipid chain modification and already possess good amphiphilicity. This is the first time that a diphtheria toxin-derived helper T-helper epitope was covalently linked to a glycopeptide antigen to enhance its immunogenicity, and this study may provide an effective vaccine design strategy for MUC1-targeted antitumor vaccines and offer novel insights into the design of fully synthetic peptide vaccines.

Reprogramming the genetic code with flexizymes.

In the canonical genetic code, the 61 sense codons are assigned to the 20 proteinogenic amino acids. Advancements in genetic code manipulation techniques have enabled the ribosomal incorporation of nonproteinogenic amino acids (npAAs). The critical molecule for translating messenger RNA (mRNA) into peptide sequences is aminoacyl-transfer RNA (tRNA), which recognizes the mRNA codon through its anticodon. Because aminoacyl-tRNA synthetases (ARSs) are highly specific for their respective amino acid-tRNA pairs, it is not feasible to use natural ARSs to prepare npAA-tRNAs. However, flexizymes are adaptable aminoacylation ribozymes that can be used to prepare diverse aminoacyl-tRNAs at will using amino acids activated with suitable leaving groups. Regarding recognition elements, flexizymes require only an aromatic ring in either the leaving group or side chain of the activated amino acid, and the conserved 3'-end CCA of the tRNA. Therefore, flexizymes allow virtually any amino acid to be charged onto any tRNA. The flexizyme system can handle not only L-α-amino acids with side chain modifications but also various backbone-modified npAAs. This Review describes the development of flexizyme variants and discusses their structure and mechanism and their applications in genetic code reprogramming for the synthesis of unique peptides and proteins.

Renal-Clearable Organic Probes From D-A-D Type Aza-BODIPY Fluorophores for Multiphoton Deep-Brain Imaging.

Bright near-infrared (NIR) fluorescent probes play an important role in in vivo optical imaging. Here, renal-clearable nanodots prepared from Aza-BODIPY are reported fluorophores for multiphoton brain imaging. The design of donor-acceptor-donor (D-A-D) type conjugated structures endowed the fluorophores with large three-photon absorption cross-section for both 1620 and 2200nm excitation. The side chain modification and lipid encapsulation yield ultrasmall nanodots (≈4nm) and a high fluorescence quantum yield (≈0.35) at 720nm emission in the aqueous phase. The measured three-photon action cross-section of a single Aza-BODIPY fluorophore in the nanodots is ≈30 times higher than the commonly used Sulforhodamine 101 dye. Three-photon deep brain imaging of subcortical structures is demonstrated, reaching a depth of 1900µm below the brain surface in a live mouse study. The nanodots enabled blood flow measurement at a depth of 1617µm using line scanning three-photon microscopy (3PM). This work provides superior fluorescent probes for multiphoton deep-brain imaging.

Side-chain-induced changes in aminated chitosan: Insights from molecular dynamics simulations

Chitosan is a functional polymer with diverse applications in biomedicine, agriculture, water treatment, and beyond. Via derivatization of pristine chitosan, its functionality can be tailored to desired applications, e.g. immobilization of biomolecules. Here, we performed molecular dynamics simulations of three aminated chitosan polymers, where one, two, and three long-distanced side chains have been incorporated. These polymers have been previously synthesized and their properties were investigated experimentally, however, the observed dependencies could not be fully explained on the molecular level. Here, we develop a computational protocol for the simulation of functionalized chitosan polymers and perform advanced analysis of their conformational states, intramolecular interactions, and water binding. We demonstrate that intra- and intermolecular forces, especially hydrogen bonds induced by polymer side chain modifications, modulate dihedral angle conformational states of the polymer backbone and interactions with water. We explain the role of the chemical composition of the functionalized chitosans in their tendency to collapse and reveal the key role of the protonation of the amino group near the polymer backbone on the reduction of polymer collapse. We demonstrate that specific binding of water molecules, especially the intermediate water, is more pronounced in the polymer exhibiting such an amino group.

Inner Side Chain Modification of Small Molecule Acceptors Enables Lower Energy Loss and High Efficiency of Organic Solar Cells Processed with Non-halogenated Solvents.

Organic solar cells (OSCs) processed with non-halogenated solvents usually suffer from excessive self-aggregation of small molecule acceptors (SMAs), severe phase separation and higher energy loss (Eloss), leading to reduced open-circuit voltage (Voc) and power conversion efficiency (PCE). Regulating the intermolecular interaction to disperse the aggregation and further improve the molecular packing order of SMAs would be an effective strategy to solve this problem. Here, we designed and synthesized two SMAs L8-PhF and L8-PhMe by introducing different substituents (fluorine for L8-PhF and methyl for L8-PhMe) on the phenyl end group of the inner side chains of L8-Ph, and investigated the effect of the substituents on the intermolecular interaction of SMAs, Eloss and performance of OSCs processed with non-halogenated solvents. Through single crystal analysis and theoretical calculations, it is found that compared with L8-PhF, which possesses strong and abundant intermolecular interactions but downgraded molecular packing order, L8-PhMe with the methyl substituent possesses more effective non-covalent interactions, which improves the tightness and order of molecular packing. When blending the SMAs with polymer donor PM6, the differences in intermolecular interactions of the SMAs influenced the film formation process and phase separation of the blend films. The L8-PhMe based blend film exhibits shorten film formation and more homogeneous phase separation than those of the L8-PhF and L8-Ph based ones. Especially, the OSCs based on L8-PhMe show reduced non-radiative energy loss and enhanced Voc than the devices based on the other two SMAs. Consequently, the L8-PhMe based device processed with o-xylene (o-XY) and using 2PACz as the hole transport layer (HTL) shows an outstanding PCE of 19.27 %. This study highlights that the Eloss of OSCs processed with non-halogenated solvents could be decreased through regulating the intermolecular interactions of SMAs by inner side chain modification, and also emphasize the importance of effectivity rather than intensity of non-covalent interactions introduced in SMAs on the molecular packing, morphology and PCE of OSCs.

Trinucleotide cap analogs with triphosphate chain modifications: synthesis, properties, and evaluation as mRNA capping reagents.

The recent COVID-19 pandemics have demonstrated the great therapeutic potential of in vitro transcribed (IVT) mRNAs, but improvements in their biochemical properties, such as cellular stability, reactogenicity and translational activity, are critical for further practical applications in gene replacement therapy and anticancer immunotherapy. One of the strategies to overcome these limitations is the chemical modification of a unique mRNA 5'-end structure, the 5'-cap, which is responsible for regulating translation at multiple levels. This could be achieved by priming the in vitro transcription reaction with synthetic cap analogs. In this study, we combined a highly efficient trinucleotide IVT capping technology with several modifications of the 5' cap triphosphate bridge to synthesize a series of 16 new cap analogs. We also combined these modifications with epigenetic marks (2'-O-methylation and m6Am) characteristic of mRNA 5'-ends in higher eukaryotes, which was not possible with dinucleotide caps. All analogs were compared for their effect on the interactions with eIF4E protein, IVT priming, susceptibility to decapping, and mRNA translation efficiency in model cell lines. The most promising α-phosphorothiolate modification was also evaluated in an in vivo mouse model. Unexpected differences between some of the analogs were analyzed using a protein cell extract pull-down assay.

Synthesis and characterization of new naphthalene diimides (NDIs) for application in electronic devices

This paper describes the synthesis of new naphthalene diimide (NDI) derivatives obtained in good yields from the reaction between 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and different p-alkoxy-substituted anilines. The photophysical properties of the NDIs were investigated in solution and the solid state. UV–visible absorption spectra in 1,4-dioxane, dichloromethane, and acetonitrile showed absorption maxima at approximately 375 nm, related to symmetry and spin allowed 1π-π* electronic transitions. These compounds did not exhibit fluorescence emission in the studied solvents. Electrochemical studies have indicated that the presence of different alkyl chains significantly affects the capacity of NDIs when used as organic cathodes in Al-graphite batteries due to variations in their ability to intercalate tetrachloroaluminate. The organic cathodes incorporating NDIs with varying alkyl chain lengths exhibited distinct capacities: 123.5 mA h g⁻1 for 3a, 101.6 mA h g⁻1 for 3b, and 157.3 mA h g⁻1 for 3c, with a capacity retention of approximately 54 % after 15 charge‒discharge cycles. These findings highlight the crucial role of alkyl chain modification in optimizing the electrochemical performance of organic cathodes.

Corrin Ring Modifications Reveal the Chemical and Spatial Requirements for the B12-btuB Riboswitch Interaction.

The btuB riboswitch is a regulatory RNA sequence controlling gene expression of the outer membrane B12 transport protein BtuB by specifically binding coenzyme B12 (AdoCbl) as its natural ligand. The B12 sensing riboswitch class is known to accept various B12 derivatives, leading to a division into two riboswitch subclasses, dependent on the size of the apical ligand. Here we focus on the role of side chains b and e on affinity and proper recognition, i. e. correct structural switch of the btuB RNA, which belongs to the AdoCbl-binding class I. Chemical modification of these side chains disturbs crucial hydrogen bonds and/or electrostatic interactions with the RNA, its effect on both affinity and switching being monitored by in-line probing. Chemical modifications at sidechain b of vitamin B12 show larger effects indicating crucial B12-RNA interactions. When introducing the same modification to AdoCbl the influence of any side-chain modification tested is reduced. This renders the impact of the adenosyl-ligand for B12-btuB riboswitch recognition clearly beyond the known role in affinity.

Improving Photophysical Properties and Hydrophily of Conjugated Polymers Simultaneously by Side-Chain Modification for Near-Infrared Cell Imaging.

Conjugated polymers (CPs)-based near-infrared phototheranostics are receiving increasing attention due to their high molar extinction coefficient, wide emission wavelength, easy preparation and excellent biocompatibility. Herein, several new conjugated polymers with D2-D1-A structures were easily prepared through one-pot coupling using triphenylamine (D2) as well as thiophenes (D1) as electron donors and benzothiadiazole (A) as electron acceptors. Interesting, their optical performance and power conversion efficiency could be tuned by side chains on thiophenes (D1). The introduction of ethylenedioxy into D1 as side chain significantly improves fluorescence imaging brightness, photothermal conversion efficiency and hydrophilicity, and extends emission wavelength, which are beneficial for phototheranostic. The side chain modification provides new opportunity to design efficient phototheranostics without construction new fluorescent skeletons.

Design, synthesis, and optimization of novel PD-L1 inhibitors and the identification of a highly potent and orally bioavailable PD-L1 inhibitor

In this paper we report the discovery of structurally novel and highly potent programmed cell death-ligand 1 (PD-L1) inhibitors targeting surface and intracellular PD-L1. A ring fusion design utilizing dimethoxyphenyl indazole derivatives was used, followed by structural extension, which further improved potency by inducing the formation of additional symmetrical interactions within the PD-L1 binding site, leading to the discovery of novel and highly active tetra-aryl-scaffold inhibitors. Key optimizations involved polar tail chain modifications that improve potency and minimize cell cytotoxicity. In addition, druggability issues that exist outside the rule-of-five chemical space were addressed. CB31, a representative compound, was found to exhibit outstanding activity in blocking programmed cell death-1 (PD-1)/PD-L1 interactions (IC50 = 0.2 nM) and enhancing T-cell functions, with minimal cell cytotoxicity. CB31 also displayed favorable oral pharmacokinetic properties, consistent with its high passive permeability and insusceptibility to efflux transporters, as well as its high metabolic stability. Additionally, CB31 demonstrated mechanistically differentiated features from monoclonal antibodies by inducing PD-L1 internalization, intracellular retention of PD-L1 with altered glycosylation pattern, and PD-L1 degradation. It also demonstrated greater effects on tumor size reduction and tumor cell killing, with enhanced T-cell infiltration, in a 3D tumor spheroid model. Overall, results show that CB31 is a promising small-molecule PD-L1 inhibitor that can inhibit PD-1/PD-L1 interactions and promote PD-L1 degradation.

Synthesis and Biological Evaluations of Granulatamide B and its Structural Analogues.

While granulatamides A and B have been previously isolated, their biological activities have been only partially examined. The aim of this study was to synthesize granulatamide B (4b), a tryptamine-derivative naturally occurring in Eunicella coral species, using the well-known procedure of Sun and Fürstner and its 12 structural analogues by modifying the side chain, which differs in length, degree of saturation as well as number and conjugation of double bonds. The prepared library of compounds underwent comprehensive assessment for their biological activities, encompassing antioxidative, antiproliferative, and antibacterial properties, in addition to in vivo toxicity evaluation using a Zebrafish model. Compound 4i, which consists of a retinoic acid moiety, exhibited the strongest scavenging activity against ABTS radicals (IC50 = 36 ± 2 μM). In addition, 4b and some of the analogues (4a, 4c and 4i), mostly containing an unsaturated chain and conjugated double bonds, showed moderate but non-selective activity with certain IC50 values in the range of 20-40 μM. In contrast, the analogue 4l, a derivative of alpha-linolenic acid, was the least toxic towards normal cell lines. Moreover, 4b was also highly active against Gram-positive Bacillus subtilis with an MIC of 125 μM. Nevertheless, both 4b and 4i, known for the best-observed effects, caused remarkable developmental abnormalities in the zebrafish model Danio rerio. Since modification of the side chain did not significantly alter the change in biological activities compared to the parent compound, granulatamide B (4b), the substitution of the indole ring needs to be considered. Our group is currently carrying out new syntheses focusing on the functionalization of the indole core.

PICKAPEP: An application for parameter calculation and visualization of cyclized and modified peptidomimetics.

The interest in peptides and especially in peptidomimetic structures has risen enormously in the past few years. Novel modification strategies including nonnatural amino acids, sophisticated cyclization strategies, and side chain modifications to improve the pharmacokinetic properties of peptides are continuously arising. However, a calculator tool accompanying the current development in peptide sciences towards modified peptides is missing. Herein, we present the application PICKAPEP, enabling the virtual construction and visualization of peptidomimetics ranging from well-known cyclized and modified peptides such as ciclosporin A up to fully self-designed peptide-based structures with custom amino acids. Calculated parameters include the molecular weight, the water-octanol partition coefficient, the topological polar surface area, the number of rotatable bonds, and the peptide SMILES code. To our knowledge, PICKAPEP is the first tool allowing users to add custom amino acids as building blocks and also the only tool giving the possibility to process large peptide libraries and calculate parameters for multiple peptides at once. We believe that PICKAPEP will support peptide researchers in their work and will find wide application in current as well as future peptide drug development processes. PICKAPEP is available open source for Windows and Mac operating systems (https://www.research-collection.ethz.ch/handle/20.500.11850/681174).

Synthesis and Characterization of Multifunctional Symmetrical Squaraine Dyes for Molecular Photovoltaics by Terminal Alkyl Chain Modifications

Novel far-red sensitive symmetric squaraine (SQ) dyes with terminal alkyl chain modifications were designed, synthesized, and characterized, aiming towards imparting multifunctionalities such as photosensitization, dye aggregation prevention, and source of electrolyte components. The dye sensitizer SQ-80 with alkyl chain terminal modifications consisting of 1-methylimidazolium iodide was designed and synthesized as a new dye sensitizer for DSSCs based on symmetric SQ-4 without any terminal modification used as reference. Upon adsorption on the mesoporous TiO2 surface, SQ-80 demonstrated reduced dye aggregation and stronger binding to the TiO2 surface, leading to enhanced durability of DSSCs. Apart from the most common photosensitization behavior, the newly designed dye demonstrated multifunctionalities such as aggregation prevention and electrolyte functionality, utilizing iodine-based redox electrolytes in the presence and absence of I2 and LiI additives. In the absence of LiI and I2, a mixture of SQ-77 with alkyl chain terminal modifications consisting of iodide and SQ-80 demonstrated a photoconversion efficiency of 1.54% under simulated solar irradiation, which was about six times higher compared with the reference dye SQ-4 (0.24%) (having no alkyl chain terminal modification).

Hydrophobic Microenvironment Modulation of Ru Nanoparticles in Metal-Organic Frameworks for Enhanced Electrocatalytic N2 Reduction.

The modulation of the chemical microenvironment surrounding metal nanoparticles (NPs) is an effective means to enhance the selectivity and activity of catalytic reactions. Herein, a post-synthetic modification strategy is developed to modulate the hydrophobic microenvironment of Ru nanoparticles encapsulated in a metal-organic framework (MOF), MIP-206, namely Ru@MIP-Fx (where x represents perfluoroalkyl chain lengths of 3, 5, 7, 11, and 15), in order to systematically explore the effect of the hydrophobic microenvironment on the electrocatalytic activity. The increase of perfluoroalkyl chain length can gradually enhance the hydrophobicity of the catalyst, which effectively suppresses the competitive hydrogen evolution reaction (HER). Moreover, the electrocatalytic production rate of ammonia and the corresponding Faraday efficiency display a volcano-like pattern with increasing hydrophobicity, with Ru@MIP-F7 showing the highest activity. Theoretical calculations and experiments jointly show that modification of perfluoroalkyl chains of different lengths on MIP-206 modulates the electronic state of Ru nanoparticles and reduces the rate-determining step for the formation of the key intermediate of N2H2 *, leading to superior electrocatalytic performance.