Acetylation Research Articles

Microcrystalline cellulose acetate incorporating cyanoacetyl moiety

AbstractThis work is part of our research to develop facile green methods for synthesizing bioactive molecules from biomass. The current study deals with the preparation and investigation of the newly synthesized cyanoacetyl-acetylated microcrystalline cellulose (CAA-MCC). The novelty of this derivative lies not only in its ability to act as a green dry-film biocide/UV blocker for eco-friendly waterborne paints but also in being biomass-derived via solar pulping of rice straw, which is a mild process that produces cellulosic pulp and non-toxic black liquor. Solar acid dissociation of the bleached pulp produces microcrystalline cellulose (MCC), which was utilized to synthesize its acetate derivative incorporating the cyanoacetyl moiety (CAA-MCC). The presence of acetyl and cyano acetyl groups in CAA-MCC was confirmed using elemental and spectral analyses, including FT-IR and NMR. Two sets of paint formulations were prepared, one with CAA-MCC and the other with the commercial dry-film biocide Rocima 363. Scanning electron microscope (SEM) and energy-dispersive X-ray (EDAX) analyses were performed for MCC, CAA-MCC, and the prepared dry films. CAA-MCC demonstrated moderate antibacterial activity, encouraging its evaluation as a dry-film biocide and UV blocker. CAA-MCC paint films showed resistance to microbial growth on their surfaces without inhibition zones. Moreover, films were exposed to ultraviolet (UV) radiation while monitoring their color change over time. The results revealed that films containing CAA-MCC were more resistant to deterioration than those containing Rocima 363. Viscosity, X-cut adhesion, hardness, and water resistance were also evaluated, and they all improved with the CAA-MCC addition. CAA-MCC could act as a new, cost-effective alternative to petrochemical-derived biocides and UV blockers that can improve paint performance. Graphical Abstract

Enhanced Rheological and Structural Properties of the Exopolysaccharide from Rhizobium leguminosarum VF39 Through NTG Mutagenesis

Microbial exopolysaccharides (EPSs) are biopolymer materials with advantages such as biodegradability, biocompatibility, ease of mass production, and reproducibility. The EPS that was isolated from Rhizobium leguminosarum bv. viciae VF39 is an anionic polysaccharide with a backbone structure consisting of one galactose, five glucose molecules, and two glucuronic acids, along with 3-hydroxybutanoyl, acetyl, and pyruvyl functional groups. Through N-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutagenesis, we isolated and purified a mutant EPS from VF39, VF39 #54, which demonstrated enhanced physicochemical and rheological properties compared to the wild-type VF39. The EPS structure of the VF39 #54 mutant strain showed a loss of glucuronic acid and 3-hydroxybutanoyl groups compared to the wild-type, as confirmed by FT-IR, NMR analysis, and uronic acid assays. The molecular weight of the VF39 #54 EPS was 250% higher than that of the wild-type. It also exhibited improved viscoelasticity and thermal stability. In the DSC and TGA analyses, VF39 #54 had a higher endothermic peak (172 °C) compared to the wild-type (142 °C), and its thermal decomposition point was 260 °C, surpassing the wild-type’s value of 222 °C. Additionally, the VF39 #54 EPS maintained a similar viscosity to the wild-type in various pH, temperature, and metal salt conditions, while also exhibiting a higher overall viscosity. The cytotoxicity test using HEK-293 cells confirmed that the VF39 #54 EPS was non-toxic. Due to its high viscoelastic properties, the VF39 #54 EPS shows potential for use in products such as thickeners, texture enhancers, and stabilizers. Furthermore, its thermal stability and biocompatibility make it a promising candidate for applications in food, pharmaceuticals, and cosmetic formulations. Additionally, its ability to maintain viscosity under varying environmental conditions highlights its suitability for industrial processes that require consistent performance.

Role of the CTCF/p300 axis in osteochondrogenic-like differentiation of polyploid giant cancer cells with daughter cells.

Polyploid giant cancer cells (PGCCs) have properties of cancer stem cells (CSCs). PGCCs with daughter cells (PDCs) undergo epithelial-mesenchymal transition and show enhanced cellular plasticity. This study aimed to elucidate the mechanisms underlying the osteo/chondrogenic-like differentiation of PDCs, which may be exploited therapeutically by transdifferentiation into post-mitotic and functional cells. Cobalt chloride was used to induce PGCC formation in MDA-MB-231 and HEY cells, and PDCs were cultured in osteo/chondrogenic differentiation media. Alcian blue staining was used to confirm osteo/chondrogenic differentiation, and the cell cycle was detected using flow cytometry. The expression of osteo/chondrogenic differentiation-related proteins was compared, and a co-immunoprecipitation assay was used to demonstrate the interactions between proteins. Bioinformatic analysis was used to explore the regulatory mechanism of osteo/chondrogenic differentiation, and a dual-luciferase reporter assay was performed to validate the interaction between transcriptional factors and target genes. Animal xenograft models were used to confirm the osteo/chondrogenic differentiation of PDCs. When cultured in osteo/chondrogenic medium, the stemness of PDCs decreased, and the expression of osteo/chondrogenic-related markers increased. This osteo/chondrogenic-like process was regulated by the transforming growth factor-β pathway in a time-dependent manner. A concurrent increase in the expression of histone acetyltransferase p300 and the transcription factor CCCTC-binding factor (CTCF) was observed. Co-immunoprecipitation assays revealed that p300 acetylated the osteo/chondrogenic marker RUNT-related transcription factor 2 (RUNX2). Analysis of chromatin immunoprecipitation sequencing datasets revealed that both CTCF and histone H3 lysine 27 acetylation (H3K27ac) were enriched in the promoter region of E1A-associated protein p300 (P300). The four predicted binding sites for CTCF and P300 were validated using dual-luciferase reporter assays. We examined the interaction between CTCF and H3K27ac and found that these two proteins had a combined effect on the transactivation of P300. CTCF, in synergy with H3K27ac, amplified the expression of P300, facilitating acetyl group transfer to RUNX2. This acetylation stabilized RUNX2 and promoted osteo/chondrogenic differentiation, thereby reducing the incidence of PDC malignancies.

Unraveling the Band Structure and Orbital Character of a π-Conjugated 2D Graphdiyne-Based Organometallic Network.

Graphdiyne-based carbon systems generate intriguing layered sp-sp2 organometallic lattices, characterized by flexible acetylenic groups connecting planar carbon units through metal centers. At their thinnest limit, they can result in 2D organometallic networks exhibiting unique quantum properties and even confining the surface states of the substrate, which is of great importance for fundamental studies. In this work, the on-surface synthesis of a highly crystalline 2D organometallic network grown on Ag(111) is presented. The electronic structure of this mixed honeycomb-kagome arrangement - investigated by angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy - reveals a strong electronic conjugation within the network, leading to the formation of two intense electronic band-manifolds. In comparison to theoretical density functional theory calculations, it is observed that these bands exhibit a well-defined orbital character that can be associated with distinct regions of the sp-sp2 monomers. Moreover, it is found that the halogen by-products resulting from the network formation locally affect the pore-confined states, causing a significant energy shift. This work contributes to the understanding of the growth and electronic structure of graphdiyne-like 2D networks, providing insights into the development of novel carbon materials beyond graphene with tailoredproperties.

Understanding the relationship between preferential interactions of peptides in water-acetonitrile mixtures with protein-solvent contact surface area.

The influence of polar, water-miscible organic solvents (POS) on protein structure, stability, and functional activity is a subject of significant interest and complexity. This study examines the effects of acetonitrile (ACN), a semipolar, aprotic solvent, on the solvation properties of blocked Ace-Gly-X-Gly-Nme tripeptides (where Ace and Nme stands for acetyl and N-methyl amide groups respectively and X is any amino acid) through extensive molecular dynamics simulations. Individual simulations were conducted for each peptide, encompassing five different ACN concentrations within the range of χACN = 0.1-0.9. The preferential solvation parameter (Γ) calculated using the Kirkwood-Buff integral method was used for the assessment of peptide interactions with water/ACN. Additionally, weighted Voronoi tessellation was applied to obtain a three-way data set containing four time-averaged contact surface area types between peptide atoms and water/ACN atoms. A mathematical technique known as N-way Partial Least Squares (NPLS) was utilized to anticipate the preferential interactions between peptides and water/ACN from the contact surface areas. Furthermore, the temperature dependency of peptide-solvent interactions was investigated using a subset of 10 amino acids representing a range of hydrophobicities. MD simulations were conducted at five temperatures, spanning from 283 to 343K, with subsequent analysis of data focusing on both preferential solvation and peptide-solvent contact surface areas. The results demonstrate the efficacy of utilizing contact surface areas between the peptide and solvent constituents for successfully predicting preferential interactions in water/ACN mixtures across various ACN concentrations and temperatures.

Synthesis of Clickable Isotactic Poly(vinyl ether)s through Organocatalytic Stereoselective Cationic Copolymerization.

By virtue of the high reliability of click chemistry, polymers with clickable groups provide a useful platform for the rapid synthesis of polymer materials with diverse functionalities and architectures. However, the polymerization of clickable vinyl monomers with a concurrent regulation on tacticity remains underdeveloped. Herein, we report the successful development of a stereoselective cationic copolymerization of C-C triple bond-containing vinyl ethers with simple alkyl vinyl ethers by employing confined Brønsted acid as catalyst, which allows for the synthesis of alkyne-functionalized vinyl ether copolymers with high isotacticity (up to 90% m), controlled molecular weight, and variable content of C-C triple bonds. Further transformation of the pendant clickable alkyne groups via thiol-yne click reactions and copper(I)-catalyzed alkyne-azide cycloaddition reaction enables a modular access to isotactic polymers with various functional groups.

Novel Ratiometric Surface-Enhanced Raman Scattering (SERS) Biosensor for Ultrasensitive Quantitative Monitoring of Human Carboxylesterase-1 in Hepatocellular Carcinoma Cells Using Ag-Au Nanoflowers as SERS Substrate.

In this study, we developed ratiometric surface-enhanced Raman scattering (SERS) biosensors using Ag-Au alloy nanoflowers as SERS substrates, molecules having amide bonds and alkyne groups (Tag A) as Raman reporters, and sodium thiocyanate as an internal standard molecule (Tag B) for the sensitive detection of human carboxylesterase-1 (hCE1) in HepG-2 cells. The correlation between HepG-2 cell damage and hCE1 activity levels was investigated. Both Tag A's alkyne group and Tag B's cyanide group produced characteristic SERS signals in the Raman-silent region (I2000cm-1 and I2115cm-1, respectively). The hydrolysis of the amide bond in Tag A via hCE1 and the shedding of the alkyne group led to a reduction in the SERS signal intensity observed at I2000cm-1. Conversely, the SERS signal intensity of Tag B at I2115cm-1 exhibited a consistent pattern. As the activity level of hCE1 and the ratiometric peak intensity (I2000cm-1/I2115cm-1) correlated negatively, hCE1 could be quantitatively detected within the range of 10-2 to 2 × 102 ng·mL-1, with a detection limit of 7.3 pg·mL-1. The ratiometric SERS probe strategy, in which a ratio response is employed, permits sensitive and reproducible SERS detection by facilitating intrinsic calibration to rectify signal fluctuations resulting from temporal and spatial variations in the detection conditions. Concurrently, the implementation of Raman-silent region reporter molecules mitigates the interference from endogenous biomolecules in SERS measurements and offers a novel approach for achieving highly sensitive and interference-free detection of intracellular hCE1.

Template Synthesis of the Iron(III) Complex with the Ligands Based on Acylpyrazolonepyridines

The reaction of new bidentate ligand, 1-(5-hydroxy-1-methyl-3-(pyridin-2-yl)-1Н-pyrazol-4-yl)ethan-1-one (L), with iron(III) chloride affords the mononuclear iron(III) complex FeL₂Cl₃, which is characterized by XRD (CIF file CCDC no. 2309481). The intramolecular hydrogen bond between the protonated pyridyl and acetyl groups in ligand L, which exists in the crystal as a zwitterion, provides the formation of rarely met iron complexes in which the β-diketonate fragment coordinates via the η1 mode. A similar coordination mode along with a possibility of a more favorable η2 coordination provides new possibilities for the design of heteropolynuclear compounds of various structures used in the fabrication of molecular devices of data storage and processing.

Elegant approach to intervention of homogalacturonan from the fruits of Ficus pumila L. in colitis: Unraveling the role of methyl esters and acetyl groups

Elegant approach to intervention of homogalacturonan from the fruits of Ficus pumila L. in colitis: Unraveling the role of methyl esters and acetyl groups

The effects of acetylated cordycepin derivatives on promoting vascular angiogenesis and attenuating myocardial ischemic injury

BackgroundEnhanced angiogenesis following myocardial infarction (MI) is beneficial to preserve cardiac function. The present study aimed to investigate whether acetylated derivatives of cordycepin altered its original antitumor properties and exerted cardioprotective effects by promoting angiogenesis in vitro and in vivo. MethodsCordycepin and its derivatives with single (DA), double (DAA), and triple acetyl groups (DAAA) were assessed. The cell viability of leukemia U937 cells, malignant hepatoma Huh-7 cells, and human umbilical vascular endothelial cells (HUVECs) treated with cordycepin, DA, DAA, and DAAA were determined. The expression of β-catenin in U937 cells, as well as the expression of p65, p38 and other related signal regulators in HUVECs elicited by lipopolysaccharides (LPS) were also observed. Angiogenesis was determined by tube formation in HUVECs and Matrigel plug assay in mice. Cardiac function following administration of DAAA was evaluated in mice MI model simulated by coronary artery ligation. ResultsThe inhibitory effects of cordycepin and its acetylated derivatives on U937 cells, Huh-7 cells, HUVECs, and the expression of β-catenin in U937 cells were mitigated with increasing acetylation. Intriguingly, DAAA preserved the cell viability of HUVECs compared to other acetylated derivatives. Although DAAA had a significantly diminished antitumor effect compared to cordycepin, it promoted angiogenesis in mice and tube formation in HUVECs and attenuated LPS-induced phosphorylation of p65 and p38. Additionally, administration of DAAA improved cardiac function following coronary artery ligation in mice. ConclusionDAAA could be considered a promising adjunctive therapy to prevent post-MI heart failure through promoting angiogenesis.

The general glycan profiling of Dendrobium officinale and their protective effects on MIN6 cells via ERK signaling pathway

Based on structural elucidation of natural and hydrolyzed glycans, the general glycans profiling of D. officinale were unequivocally established for the first time as follows: [Display omitted] The results indicated that the structure of D. officinale glycans with low degree of polymerization (DP ≤ 22) was linear α-D-1,4-glucan, whereas the structure of glycans with high degree of polymerization (DP > 24) was linear acetylated 1,4-glucomannan. The content of acetyl groups and mannose to glucose (M/G) ratio increased with the degree of polymerization of D. officinale glycans. In addition, this study showed that natural D. officinale glycans protected pancreatic β-cell damage induced by glucotoxicity through the extracellular signal–regulated kinase (ERK)1/2 pathway.

Totally conjugated and coplanar covalent organic frameworks as photocatalysts for water purification: Reduction of Cr (VI) while oxidizing water borne organic pollutants

Covalent organic frameworks (COFs) have emerged as photocatalytic materials with bandgaps in the visible region. Imine-based COFs, which have been extensively explored, often suffer from limited stability and poor conjugation, hindering their photocatalytic activities. The chemical and hydrolytic stability and the photocatalytic performance of COFs is drastically enhanced by constructing 2D COFs that are fully conjugated in the x,y plane, that have alternating donor–acceptor (D-A) units for better charge separation and that have enhanced conjugation in the z-axis by p-orbital overlap by using highly planar building blocks. In this study, we introduce three highly crystalline sp2 COFs that are able to photocatalyticlly reduce highly toxic Cr (VI) species to much less toxic and easily removable Cr (III) residues, while simultaneously oxidizing water borne organic pollutants. One of them, the TEB-COF, with the integration of the acetylene group, exhibited excellent photocatalytic activity due to its superior planarity and extended conjugation. TEB-COF is able to completely remove the model dye Rhodamine B and Cr (VI) (10 mg/L) in less than 30 min. This research provides valuable insights into the development of recyclable metal-free photocatalysts for wastewater treatment.

A novel esterase regulates Klebsiella pneumoniae hypermucoviscosity and virulence.

Klebsiella pneumoniae, an emerging multidrug-resistant pathogen, exhibits hypermucoviscosity (HMV) as a critical virulence trait mediated by its capsular polysaccharide (CPS). Recent discoveries have determined acetylation as a significant modification for CPS, although its impact on HMV and virulence was previously unknown. This study elucidates the roles of two enzymes: Klebsiella pneumoniae Acetylated CPS Esterase (KpACE), an esterase that removes acetyl groups from CPS, and WcsU, an acetyltransferase that adds acetyl groups to CPS. KpACE is highly upregulated in an ompR-deficient mutant lacking HMV, and its overexpression consistently reduces HMV and diminishes virulence in a mouse model of pneumonia. The esterase domain-containing KpACE effectively deacetylates model sugar substrates and CPS-K2. Site-directed mutagenesis of the conserved catalytic histidine residue at position 370 significantly reduces its enzymatic activity. This reduction correlates with decreased HMV, affecting key virulence traits including biofilm formation and serum resistance. Similarly, a deficiency in the wcsU gene abolishes CPS acetylation, and reduces HMV and virulence. These results highlight the importance of the delicate balance between CPS acetylation by WcsU and deacetylation by KpACE in regulating the pathogenicity of K. pneumoniae. Understanding this balance provides new insights into the modulation of virulence traits and potential therapeutic targets for combating K. pneumoniae infections.

Histone Deacetylases in Metabolism: The Known and the Unexplored.

Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl groups from key lysine residues on histone and non-histone proteins and thereby regulate gene transcription. They have been implicated in several biological processes in both healthy and pathologic settings. This review discusses the role of HDACs in multiple metabolically active tissues and highlights their contribution to the pathogenesis of tissue-specific maladaptation and diseases. We also summarize the current knowledge gaps and potential ways to address them in future studies.

Circulating metabolites in patients with chronic heart failure are related to increased lipid utilisation but not to gut microbiota alterations

Abstract Background The gut microbiota produces numerous metabolites that can enter the circulation and exert their effects outside the gut. Some have been implicated in the pathogenesis of chronic heart failure (HF). Several studies have reported altered gut microbiota composition and circulating metabolites in patients with chronic HF compared to healthy controls (HC). However, limited data is available on the potential interplay between the dysbiotic features of the gut microbiota and the altered circulating metabolome in these patients. Purpose To examine differences in circulating metabolites between patients with chronic HF and HC, and their association with cardiac function and gut dysbiosis. Methods We included 123 patients, aged 18-75 years, with stable chronic HF and left ventricular ejection fraction (LVEF) <40%, and 51 HC. We collected fasting blood samples for metabolomic and lipidomic analyses, which were performed using liquid chromatography tandem mass spectrometry. A web-based platform was utilised for data preprocessing, filtering, pathway analysis, and metabolite annotation. Principal component analysis and orthogonal partial least squares discriminant analysis were used to explore differences in plasma metabolic profiles. Over-representation analysis was performed to identify the pathways in which relevant metabolites were involved. Stool samples were sequenced using 16S ribosomal RNA gene amplification. We calculated a dysbiosis index for each sample based on different abundances of microbial taxa in patients vs. controls. Results After adjusting for age and sex, we identified 73 enriched metabolites and 27 enriched lipids (odds ratio≥2 and p<0.05), and 124 depleted metabolites and 6 depleted lipids (odds ratio≤0.5 and p<0.05) in HF patients compared to HC. The enriched metabolites were involved in pathways related to lipid metabolism (beta oxidation, glycerolipid, sex hormone, and fatty acid metabolism), pyrimidine metabolism, Warburg effect, citric acid cycle, and pentose phosphate pathway. The depleted metabolites were involved in pathways related to lipid biosynthesis (fatty acids, steroids, bile acids), amino acid metabolism (glycine, serine, taurine, hypotaurine, cysteine, selenoamino acids), polyamine biosynthesis (spermidine, spermine), sulphate/sulphite metabolism, propanoate and pyruvate metabolism, carbohydrate metabolism (galactose, amino sugars, glycolysis), transfer of acetyl groups into mitochondria, urea cycle, and beta oxidation of very long chain fatty acids (Figure 1). LVEF, N-terminal pro B-type natriuretic peptide, and the dysbiosis index were not significantly related to any metabolite. Conclusions In patients with chronic HF, energy metabolism is significantly altered compared to HC, with a notable shift towards lipid utilisation. However, the alterations in circulating metabolites were not related to markers of cardiac function and appear to be unrelated to gut dysbiosis.Figure 1

Effects of Acetylation on the Morphological, Physicochemical, and Thermal Properties of Enterolobium cyclocarpum Starch

AbstractThis study investigates the impact of acetylation treatment on Enterolobium cyclocarpum (Parota) starch, focusing Morphological, Physico‐chemical and thermal impact induced by varying acetylation levels. The research employed scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) to examine the structural and thermal alterations resulting from acetylation. These analyses also evaluated the starch's thermal stability. Through titration, the degree of substitution and acetyl group content were quantified, demonstrating significant morphological transformations in the starch, such as increased particle size and the appearance of surface cracks on the granules. The study revealed that the degree of substitution, which changes with the duration of acetylation, markedly influences the starch's physicochemical properties, including hydrophobicity and thermal stability. Initially, acetylation reduced the gelatinization temperature, suggesting a decrease in the energy required for gelatinization. Over longer acetylation periods, however, the gelatinization temperature increased, likely due to enhanced crystallinity or molecular reorganization. These findings indicate that acetylated Parota starch has potential applications in the food industry as an encapsulating agent and in the thermoplastics industry as a plasticizer, dependent on the level of acetylation. This research underscores the utility of specific chemical modifications to adapt starch properties for various industrial applications.

Discovery and Characterization of BAY-184: A New Potent and Selective Acylsulfonamide-Benzofuran In Vivo-Active KAT6AB Inhibitor.

KAT6A and KAT6B genes are two closely related lysine acetyltransferases that transfer an acetyl group from acetyl coenzyme A (AcCoA) to lysine residues of target histone substrates, hence playing a key role in chromatin regulation. KAT6A and KAT6B genes are frequently amplified in various cancer types. In breast cancer, the 8p11-p12 amplicon occurs in 12-15% of cases, resulting in elevated copy numbers and expression levels of chromatin modifiers like KAT6A. Here, we report the discovery of a new acylsulfonamide-benzofuran series as a novel structural class for KAT6A/B inhibition. These compounds were identified through high-throughput screening and subsequently optimized using molecular modeling and cocrystal structure determination. The final tool compound, BAY-184 (29), was successfully validated in an in vivo proof-of-concept study.

Exploring the role of N-acetyltransferases in diseases: a focus on N-acetyltransferase 9 in neurodegeneration.

Acetyltransferases, required to transfer an acetyl group on protein are highly conserved proteins that play a crucial role in development and disease. Protein acetylation is a common post-translational modification pivotal to basic cellular processes. Close to 80%-90% of proteins are acetylated during translation, which is an irreversible process that affects protein structure, function, life, and localization. In this review, we have discussed the various N-acetyltransferases present in humans, their function, and how they might play a role in diseases. Furthermore, we have focused on N-acetyltransferase 9 and its role in microtubule stability. We have shed light on how N-acetyltransferase 9 and acetylation of proteins can potentially play a role in neurodegenerative diseases. We have specifically discussed the N-acetyltransferase 9-acetylation independent function and regulation of c-Jun N-terminal kinase signaling and microtubule stability during development and neurodegeneration.

Ferrocene Chalcone Enhanced Cyclotriphosphazene Photodiode Systems via Click Chemistry: Their Synthesis, Electrical, and Photophysical Properties.

In this study, a new ferrocene-decorated cyclotriphosphazene compound (4) was obtained by the interaction of ferrocene chalcone with azide end groups (2) and spirophosphazene (3) bearing alkyne groups using the click method. The structures of all compounds were confirmed using Fourier transform infrared, 1H, 13C APT, and 31P NMR, and MS techniques. The optical band gaps of compounds were measured, showing values of 4.75 eV for 3, 3.53 eV for 2, and 3.46 eV for final product 4. The optical band gap of compound 4 calculated by density functional theory is 3.28 eV. The electrical properties of the compounds were investigated against the frequency. The results showed that the conduction mechanism is based on the hopping model. New types of diodes were prepared by using compounds 2 and 4. The current-voltage characteristics of the compound 4 diode showed good rectification behavior. The rectification ratio of the heterojunction diode was calculated as 629. The ideality factors were 3.35 for 2 and 7.57 for 4. The barrier heights were 0.68 and 0.92, respectively. Under sunlight (20-100 mW/cm2), both diodes exhibited photodiode properties, with compound 4 being more sensitive to light. This indicates that the diodes can be used in optoelectronic devices due to their photoconductive behavior.

Ag(I)-Catalyzed Oxidative Cyclization of 1,4-Diynamide-3-ols with N-Oxide for Divergent Synthesis of 2-Substituted Furan-4-carboxamide Derivatives.

This work reports Ag(I)-catalyzed oxidative cyclizations of 1,4-diynamide-3-ols with 8-methylquinoline oxide to form 2-substituted furan-4-carboxamides. The reaction chemoselectivity is distinct from that reported in previous work by Hashmi. We performed density functional theory calculations to elucidate our proposed mechanism after evaluation of the energy profiles of two possible pathways. In this Ag(I) catalysis, the calculations suggest that the amide and alkyne groups of the 3,3-dicarbonyl-2-alkyne intermediates tend to chelate with the Ag(I) catalyst, further inducing a formyl attack at the Ag(I)-π-alkyne moiety to deliver the observed products.