Electron-donating Groups Research Articles

Synthesis of Highly Stable Coumarin-Based Fluorescent Dye, Its Photophysical Properties and Stability in PLA Film and Application Towards Sensing Toxic Ions.

New materials were designed and synthesized by introducing electron donor and acceptor groups using coumarin as the basic unit. In addition, two more materials with similar structures were synthesized for the comparison of their optical properties and stability. The solvent effect and the photo physical aggregation properties of aggregation caused quenching (ACQ) in the ratio of water and DMF were also investigated. In addition, we checked the detection ability for anions, and the optical properties of the materials at different pH were also investigated. The photo stability of these synthesized materials was studied, and interesting results were obtained. Based on these synthesized materials, we produced films by introducing color materials into PLA films. PLA film is characterized by the absence of plastic waste due to carbon reduction and biodegradation effects from using biomass instead of fossil fuels as raw materials, but it has the disadvantage of low light stability. By introducing high-photo stability pigment materials, the photo stability of the film can be corrected, and UV protection can be provided. The UV absorbance and fluorescence intensity of the film with the dye materials were checked, and the mechanical properties and thermal stability of the film changed when the coloring material was introduced compared to the conventional PLA film.

Optimization Across-The-Board: Centro-Arylated Push-Pull Tetraene Chromophores and Guest-Host Polymers for Electro-Optics.

The research and development of push-pull tetraene chromophores (PPT-phores) have contributed greatly to the field of organic electro-optic (EO) materials and devices since the inauguration of CLD-1 in 2001. This study is thus a systematic contribution to synthesize and characterize a series of centro-arylated PPT-phores based on strong electron-donating tetrahydroquinolinyl groups and variable strong electron-accepting tricyanofuran derivatives. In particular, we report the crystallographic data to show various packing modes of these PPT-phores with detailed information about bond length alternation and intermolecular interactions, the optical absorption edges of guest-host polymers by the Tauc model, and the anisotropy and dispersion of Pockels tensors for the poled polymers by attenuated total reflection spectroscopy. Such analyses have not been addressed to any significant extent previously and are fundamentally important to the future development of PPT-phore-based EO materials and devices. The poled films of several centro-arylated PPT-phores in polycarbonates exhibited large EO activities, excellent thermal stability, and tunable optical transparency at the telecom O- and C-band. The study demonstrates the effectiveness of π-bridge centro-arylation enabled by molecular shape modification and rigidity enhancement, over the relatively flexible and labile thioether or alkoxy groups, in rational design of hyperpolarizable PPT-phores for high-performance EO polymers.

SAR Study on Thiolato-Bridged Triosmium Carbonyl Clusters: Higher Reactivity Does Not Equal Higher Antiproliferative Activity.

A structure-activity relationship study on triosmium clusters of the general formula Os3(μ-H)(μ-SC6H4X)(CO)10 (2-X, where X = o-, m- or p-NH2; o-, m- or p- OH; p-H, -Br, -NO2, -COOH or -CH2COOH) show that their antiproliferative activity is through the cluster core, and the nature and position of the phenyl ring substituent X shows a significant impact on the activity. Clusters with an electron-withdrawing group are more reactive but are thus quickly consumed through reaction with serum, while those with an electron-donating group persists sufficiently to enter the cells and result in higher antiproliferative activity. Interestingly, m-substituted clusters and those with lipophilicity >6.0 also exhibit higher antiproliferative activity. In contrast, o-substituted clusters capable of intramolecular hydrogen bonding have lower cytotoxicity. The cluster 2-m-OH, with higher antiproliferative activity and lower reactivity with serum, is a potential lead compound for further mode of action studies.

Microwave-assisted Reduction of Ketones Using Decaborane in Aqueous Solution

The reduction of ketones to secondary alcohols is an essential reaction in organic chemistry, and various reagents are utilized for this purpose. Herein, we have reported the reduction of ketone using decaborane in conventional as well as microwave-assisted methods in aqueous solution. Different types of aromatic ketones containing distinct functional groups were analyzed. We observed that ketones having an electron-withdrawing group showed a faster reaction rate with higher yield as compared to the ketones with electron-donating groups. Additionally, a comparison between microwave- assisted and conventional synthesis was done by evaluating the total reaction time and percentage yield. The results indicate that microwave-assisted syntheses lead to higher yields within very short reaction times.

Chemoenzymatic Cyclization by Vanadium Chloroperoxidase for Synthesis of 4-Hydroxyisochroman-1-Ones.

4-Hydroxyisochroman-1-ones belong to the class of the secondary metabolite 3,4-dihydroisocoumarins. They exhibit a wide range of biological activities. These compounds can be synthesized through halocyclization using hypervalent iodine species or N-bromosuccinimide, followed by hydrolysis. Nonetheless, the reactions required specific conditions and generated toxic byproducts. In this study, Curvularia inaequalis vanadium chloroperoxidase (CiVCPO) catalyzed the chemoenzymatic cyclization of 2-vinylbenzoic acids with different electron-donating groups (1 a-1 e) to produce good yields of 4-hydroxyisochroman-1-ones (3 a-3 e) by adding KBr and H2O2 in citrate buffer (pH 5). The reaction mixture contained 30 % DMSO to improve substrate solubility without enzyme activity loss. The condition is more environmentally friendly than chemical methods. Therefore, it offers an alternative approach for synthesizing 4-hydroxyisochroman-1-ones.

Formation Mechanism of Polypyrrole-Coated Hollow Glass Microspheres (PPy@HGMs) Composite Powder.

Coating conductive nanoparticles onto the surface of hollow glass microspheres (HGMs) is essential for broadening their applications. However, the low density and high specific surface area of HGM powders, along with the thin walls of the cavity shells and poor surface adhesion, pose challenges for the uniform attachment of functional particles. In this study, we developed a novel integrated process that combines flotation, hydroxylation, and amination pretreatment for HGMs with in situ surface polymerization to achieve a uniform coating of polypyrrole (PPy) on the surface of HGMs. We explored the corresponding growth process and coating mechanism. Our findings indicate that the amount of coating, particle size, and uniformity of PPy on the surface of HGMs are significantly influenced by the pretreatment and the in situ polymerization time, as well as the microspheres/pyrrole feedstock ratio. The in situ polymerization on the surface of HGMs resulted in a uniform encapsulation of spherical PPy, with the average particle size of PPy-coated HGMs (PPy@HGMs) increasing by 14.60% compared to the original HGMs. The elemental nitrogen in the PPy@HGMs primarily exists in the form of C-N and N-H bonds. This study demonstrates that the surface functional groups of HGMs engage in chemical bonding and interactions with PPy molecules. Mechanistic analysis reveals that the hydroxyl and amino groups enriched on the surface of the pretreated HGMs serve as activation centers, facilitating the uniform enrichment of pyrrole monomers and promoting chain growth polymerization of the conjugated chain through nucleophilic and electrophilic interactions with the subamino groups in the pyrrole ring. Additionally, the reaction between the Lewis acid properties of PPy and the Lewis-type electron-donating amino groups in KH550 fosters strong bonding and the formation of a robust interface.

Catalytic Thioglycoside Activation with Diazo-Derived Copper Carbenes.

Traditional glycosylation methods using thioglycosides often require harsh conditions or expensive metal catalysts. This study presents a more sustainable alternative by employing copper, an earth-abundant catalyst. We developed diazo-based thioglycoside donors that, through copper catalysis, undergo intramolecular activation to form glycosyl sulfonium ions, leading to the generation of oxocarbenium ions. This versatile approach efficiently accommodates a variety of O-nucleophiles, including primary, secondary, and tertiary, as well as complex bioactive molecules. It is compatible with various glycosyl donors and protecting groups, including superarmed, armed, and disarmed systems. Notably, the methodology operates orthogonally to traditional thioglycoside and alkyne donors and has been successfully applied to the orthogonal iterative synthesis of trisaccharides. Mechanistic insights were gained by studying the electronic effects of electron-donating (OMe) and electron-withdrawing (NO2) groups on the donors, offering a valuable understanding of the intramolecular reaction pathway.

Differentiated Intra-Ligand Charge Transfer Boosting Multicolor Responsive MOF Heterostructures as Robust Anti-Counterfeiting Labels.

Metal-organic framework (MOF) heterostructures with hybrid architectures and abundant functional sites possess great potential applications in advanced information security, yet still suffer from the harsh stimuli mechanisms with restrained emission control. Herein, the differentiated design strategy on intra-ligand charge transfer is first reported to realize smart-responsive multicolor MOF heterostructures as robust anticounterfeiting labels. Designed similar MOF blocks with the differentiated intra-ligand charge transfer are integrated via time-dependent epitaxial growth to form multicolor MOF heterostructures. Different numbers of electron-donating groups in MOF blocks offer distinct space regulation on the torsion of charge transfer ligands, which trigger the diverse responsive emissions under the same mild stimuli, thus generating multiple tunable color patterns in heterostructures. These spatial-resolved MOF heterostructures with stable multicolor responsive modes permit the encoding of fingerprint information, which further functions as robust anti-counterfeiting labels with high-security convert states. These results offer a promising route for the function-oriented exploitation of smart-responsive MOF heterosystems for advanced information anticounterfeiting.

Development of Glycosylation Protocols Using Glycosyl N-Phenylethynyl Pyrrole-2-carboxylates as Donors.

We herein introduce glycosyl N-phenylethynyl pyrrole-2-carboxylates (PEPCs) as novel and highly efficient glycosyl donors. The unique inclusion of the pyrrole group, serving as both an electron-donating group and an ortho-tethering scaffold, imparts exceptional shelf stability while retaining reactivity for glycosylation reactions. PEPC donors exhibit broad utility for both O- and N-glycosylation across a variety of substrates. Additionally, their versatility and efficiency were further demonstrated in a one-pot saccharide synthesis, showcasing their potential for diverse synthetic applications.

A High-capacity Benzoquinone Derivative Anode for All-organic Long-cycle Aqueous Proton Batteries.

Quinone compounds, with the ability to uptake protons, are promising electrodes for aqueous batteries. However, their applications are limited by the mediocre working potential range and inferior rate performance. Herein, we examined quinones bearing different substituents, and for the first time introduce tetraamino-1,4-benzoquinone (TABQ) as anode material for proton batteries. The strong electron-donating amino groups can effectively narrow the band gap and lower the redox potentials of quinone materials. The protonation of amino groups and the amorphization of structure result in the formation of an intermolecular hydrogen-bond network, supporting Grotthuss-type proton conduction in the electrode with a low activation energy of 192.7 meV. The energy storage mechanism revealed by operando FT-IR and ex situ XPS features a reversible quinone-hydroquinone conversion during cycling. TABQ demonstrates a remarkable specific capacity of 307 mAh g-1 at 1 A g-1, which is one of the highest among organic proton electrodes. An all-organic proton battery of TABQ//TCBQ has also been developed, achieving exceptional stability of 3500 cycles at room temperature and excellent performance at sub-zero temperature.

Exploring Novel Pyrazole-Fused 1H-tetrazol-5-yl: Synthesis, SAR and Antimicrobial Efficacy

In this study, we present the synthesis, and biological activity of pyrazole-linked tetrazole derivatives (6A-6Q). All derivatives were screened for their antimicrobial activity against both gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella spp.). The compounds were synthesized through a five-step reaction process and further characterized using 1H NMR and LCMS spectral techniques. The synthetic compounds 6A–6Q were evaluated for their experimental antimicrobial activity, with ampicillin used as a positive control. According to the in vitro assays, compounds 6D and 6E exhibited higher activity against all tested strains due to the presence of halogens at the meta position. Molecules 6A, 6C, 6J, 6K, and 6E demonstrated good to moderate antibacterial activity based on their structure-activity relationship (SAR) studies. Conversely, compounds 6G, 6H, 6I, and 6P showed lower inhibition due to the presence of electron-donating groups in their structures towards the tested bacteria.

Dipole Moment Modulation of Terminal Groups Enables Asymmetric Acceptors Featuring Medium Bandgap for Efficient and Stable Ternary Organic Solar Cells.

This study puts forth a novel terminal group design to develop medium-band gap Y-series acceptors beyond conventional side-chain engineering. We focused on the strategical integration of an electron-donating methoxy group and an electron-withdrawing halogen atom at benzene-fused terminal groups. This combination precisely modulated the dipole moment and electron density of terminal groups, effectively attenuating intramolecular charge transfer effect, and widening the band gap of acceptors. The incorporation of these terminal groups yielded two asymmetric acceptors, named BTP-2FClO and BTP-2FBrO, both of which exhibited open-circuit voltage (Voc) as high as 0.96 V in binary devices, representing the highest VOCs among the asymmetric Y-series small molecule acceptors. More importantly, both BTP-2FClO and BTP-2FBrO exhibit modest aggregation behaviors and molecular crystallinity, making them suitable as a third component to mitigate excess aggregation of the PM6 : BTP-eC9 blend and optimize the devices' morphology. As a result, the optimized BTP-2FClO-based ternary organic solar cells (OSCs) achieved a remarkable power conversion efficiency (PCE) of 919.34 %, positioning it among the highest-performing OSCs. Our study highlights the molecular design importance on manipulating dipole moments and electron density in developing medium-band gap acceptors, and offers a highly efficient third component for high-performance ternary OSCs.

Plasma Tailoring of NH2-MIL-53 with Enhanced Fluorescence Emission for Simultaneous Detection of Multiple Heavy Metals in Water.

Indium, copper, and mercury are important raw materials in the electronics industry and often coexist in factory wastewater. Therefore, the development of a highly sensitive and selective method for the simultaneous detection of these heavy metal ions is of great significance for water quality monitoring and environmental protection. Herein, we report a NH2-MIL-53 fluorescent probe for the simultaneous detection of trace In3+, Cu2+, and Hg2+ in water. After a low-temperature NH3 plasma tailoring treatment for grafting electron-donor amine groups, the obtained NH2-MIL-53-M exhibited enhanced fluorescence emission intensity (∼6 times) coupled with selective adsorption of In3+, Cu2+, and Hg2+. This quenched the NH2-MIL-53-M fluorescence and allowed to significantly increase the selectivity and sensitivity for detection of In3+, Cu2+, and Hg2+. The fluorescence quenching constant (Ksv) values were 2.23 × 105, 1.00 × 105, and 2.74 × 104 M-1, while the limit of detection (LODs) values were 0.06, 0.14, and 0.53 μM, for In3+, Cu2+, and Hg2+, respectively. The concentrations of In3+, Cu2+, and Hg2+ in real environmental samples could be determined by addition of appropriate masking agents, and the recoveries were within the range of 94-110%. This study not only supplied a strategy for constructing a highly sensitive and selective fluorescent probe but also established a platform for simultaneous detection of multiple heavy metal ions in water.

Highly efficient iodine capture from vapor and water using UiO-66-X: Effects of functional group modifications

Radioactive iodine waste from the nuclear industry poses a critical threat to human health, and its effective capture has become an important research topic. In this study, modified UiO-66-X adsorbents (where X is ATA, BTA, or STA) were used to investigate the effects of the free functional groups in the UiO-66 skeleton on iodine capture in the vapor and solution states. The adsorption behavior revealed that the capture efficiency of UiO-66-ATA was substantially higher than that of UiO-66-BTA and UiO-66-STA because the electron-donating amino groups could enhance the I − I···π halogen bond interactions compared with the electron-withdrawing carboxyl and sulfonic acid groups. In addition, the pore volume of UiO-66-ATA was significantly higher than those of UiO-66-BTA and UiO-66-STA. In particular, the removal uptakes of UiO-66-ATA were 1108.1 mg/g (vapor phase) and 3601.9 mg/g (aqueous solution). This study is the first to investigate the effects of functional groups on the adsorption uptake of UiO-66 toward iodine. This efficient functional group modification strategy holds significant promise for the development of novel metal–organic framework adsorbents.

Theoretical exploration on the combined effect of isoelectron B-N bonds and B-N resonance skeleton on the thermally activated delayed fluorescence property

The multiple resonance thermally activated delayed fluorescence (MR-TADF) materials has become a hot spot in recent years depending on their potential in achieving an internal quantum efficiency of 100 %. The combined effect of para B-N resonance skeleton and isoelectron B-N bonds on the TADF property was investigated in details by employing density functional theory/time-dependent density functional theory (DFT/TDDFT) in this work based on four polycyclic aromatic molecules. The results show that isoelectron B-N bonds are favorable to the enhancement of spin orbital coupling (SOC) constants between the first singlet state (S1) and the first triplet state (T1), while para B-N resonance skeleton is more conducive to reducing the energy gap between S1 and T1 (ΔEST) through realizing short-range charge transfer character and keeping electron and hole localized at different atoms. Accordingly the combination of isoelectron B-N bonds and para B-N resonance skeleton in m[B-N]N1 and m[B-N]N2 could realize faster intersystem crossing (ISC) and reverse intersystem crossing (RISC) processes through larger SOC and lower ΔEST compared with BCz-BN and NBN-2 which only contain para B-N resonance skeleton and isoelectron B-N bonds, respectively. At the same time, the para B-N resonance skeleton help to stabilize the structure of polycyclic aromatic hydrocarbons and localize the vibration in low frequency region during emission from S1 to ground state. Thus larger nonradiative rates induced by the rotation of carbazole and tert-butyl carbazole in low frequency region in m[B-N]N1 and m[B-N]N2 could be easily reduced by replacing them by small functional group such as electron-donating (-CH3) and electron-withdrawing (-CN) groups. Therefore, we can obtain high TADF efficiency through combining para B-N resonance skeleton and isoelectron B-N bonds and suppressing low-frequency vibrations as in our designed molecules m[B-N]CH3 and m[B-N]CN.

Modifying functional groups of straw-based hydrogel provide soil N2O mitigation potential by complete denitrification

Farmed soil is considered to contribute more than 60% anthropogenic N2O emission which plays critical role in global warming potential. Straw-based hydrogels with abundant functional groups are commonly used in environmental and agronomic applications primarily as adsorbents. Those functional groups could mediate electron transfer in the process of adsorbates and might also regulate N2O emission. However, it was still unclear whether and how these functional groups affect the process. To address this knowledge gap, we employed spectral analysis and a robotized incubation system to determine mechanisms of different functional groups in influencing soil N2O. The results indicated that the straw-based hydrogel was capable of significantly reducing the emission of N2O in denitrification, and the electrochemical properties of the hydrogel had promoting effect of the microbial genetic potential for N2O reduction. Specifically, carboxymethyl (R-COO) and primary amine groups (R-NH2) promoted complete denitrification through electron supply. Furthermore, R-NH2 had a significant negative correlation with N2O emissions. To further verify the role of specific structures and functional groups in denitrification, we conducted an experiment using pure lignin as a template. This experiment resulted in an increase in R-NH2 content to 13.2% and a decrease in N2O emissions by 49.1% compared with straw hydrogel. These results prove the feasibility of straw-based hydrogel as a redox system to accelerate complete denitrification, and the electron-donating functional groups were significantly related to the reduction rate of N2O. Finally, based on these mechanisms, functional group targeted grafting technology was proposed to improve its ability to mitigate N2O emission reduction.

Mechanism of unactivated peroxymonosulfate-induced degradation of amino-G acid: Kinetics and transformation pathway

Amino-G acid (7-amino-1,3-naphthalenedisulfonic acid), a pollutant produced during textile preparation and in dyeing industries, is discarded in wastewater and causes ecological problems. In this study, amino-G acid (50.0 μM) could be completely removed by unactivated peroxymonosulfate (PMS) (1.0 mM) within 240 min, and the reaction kinetics exhibited strong pH dependence. A species-specific parallel reaction describes this pH dependence well, and the species-specific reaction rate constants of [amino-G acid]2− and [amino-G acid]− with HSO5− were calculated to be 0.0826 ± 0.0019 and 000122 ± 0.0027 M−1 s−1. The reactivity of the six naphthalene sulfonic acids and unactivated PMS varied according to the structure, and the amino group in naphthalene sulfonic acid, a typical electron-donating group, was more vulnerable to attack by unactivated PMS, which was further confirmed by the density functional theory results. The high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) spectral analysis results indicated that naphthalene sulfonic acid was first oxidized to hydroxylamine products and then further oxidized to nitroso compounds, which exhibited more ecological toxicity. However, as the reaction processing, the toxicity of the product gradually decreased. Our results provide new insights into the in-situ oxidation of unactivated PMS.

Boosting photocatalytic H2O2 production by incorporating extra electron-donor group over resorcinol-formaldehyde resin

Boosting photocatalytic H2O2 production by incorporating extra electron-donor group over resorcinol-formaldehyde resin

Functional Hexafluoroisopropyl Group Used in the Construction of Biologically Important Pyrimidine Derivatives.

A series of versatile 4-((1,1,1,3,3,3-hexafluoropropan-2-yl)oxy)pyridine intermediates have been developed to efficiently produce biaryls, amines, ethers, and thioethers. These hydrolysis-stable ether intermediates exhibit reactivity toward electron-donating groups and nucleophiles in cross-coupling and nucleophilic substitution reactions while surpassing the stability of corresponding aryl halides. In comparison to conventional coupling methods, this protocol offers an alternative pathway for accessing natural product and drug-like compounds without the need for metal catalysts. With assistance of this approach, we successfully obtained a potent P-glycoprotein inhibitor 4k (YS-370), a potent epidermal growth factor receptor inhibitor 4l (YS-363), and a promising lysine-specific demethylase 1 inhibitor 5g.

The role of Lewis acidity in bis(β-diketonate)zirconium(IV) complexes as catalysts for the ring-opening polymerization of δ-valerolactone

Poly(δ-valerolactone) (PVL) is a polymer that has garnered significant researcher interest due to its intriguing features and prospective uses across numerous domains, particularly in medicine. This work aimed to assess the influence of the Lewis acidity of the bis(β-diketonate)Zr catalyst complex on the ring-opening polymerization of δ-valerolactone. The ligand in the compound contains an electron-donating group, specifically the methyl group (2a). Furthermore, electron-withdrawing groups employed include phenyl (2b–2c) and trifluoromethyl groups (2d). Characterization data indicate that PVL has been successfully synthesized with a bis(β-diketonate)Zr complex catalyst. The hierarchy of Lewis acid strength for the bis(β-diketonate)Zr complex is 2c > 2b > 2d ≫ 2a. The sequence of PVL DP from highest to lowest is 2b, 2c, 2d and 2a. Nonetheless, the elevated Lewis acidity of complex 2c does not provide PVL with the greatest degree of polymerization. The steric barrier of complex 2c, which contains two phenyl groups, is larger than that in complex 2b. Consequently, the coordination process of the nucleophilic monomer with the electrophilic zirconium central atom becomes increasingly difficult.