Anti-Inflammatory Potential of Ethanolic Leaf Extract of Eupatorium adenophorum Spreng. Through Alteration in Production of TNF-α, ROS and Expression of Certain Genes

Search for a novel anti-inflammatory agent from a herbal source, such as Eupatorium adenophorum Spreng., a plant from the Eastern Himalayas, is of prime interest in the present investigation. Inflammation causes tissue destruction and development of diseases such as asthma, rheumatoid arthritis, and so forth. The ethanolic leaf extract of E. adenophorum (EEA) was administered intravenously and in other cases topically at the site of delayed type hypersensitivity (DTH) reaction in mouse foot paw induced with dinitrofluorobenzene. EEA can effectively inhibit DTH reaction and bring back normalcy to the paw much earlier than the controls. Efficacy of EEA on regulatory mechanisms for inflammation has also been considered. Intravenous administration of EEA increased the number of CD4+ T cells in spleen and tumor necrosis factor (TNF)-α in serum of DTH mice. Initially it was difficult to reconcile with the anti-inflammatory role of EEA and simultaneous induction of TNF-α, an established pro-inflammatory cytokine. EEA induces higher expression of TNF-α gene and amount of the cytokine in serum. We discussed the other role of TNF-α, its involvement in repairing tissue damage incurred in course of inflammatory reaction. EEA also induces TGF-β encoding a cytokine involved in tissue repair mechanism. EEA inhibits expression of another pro-inflammatory cytokine gene IL-1β and downregulates cycloxygenase 2 (COX2) gene responsible for metabolism of inflammatory mediators like prostaglandins. Furthermore, anti-inflammatory role of EEA is also revealed through its inhibition of hydroxyl radical generation. Notably EEA does not necessarily affect the expression of other inflammation-related genes such as IL-6, IL-10 and IKK. The present study reports and analyzes for the first time the anti-inflammatory property of the leaf extract of E. adenophorum

Well-defined hybrid Copper-based nanoreactors for electrocatalytic CO2 reduction

In the perspective of drastically reducing anthropogenic CO2 emissions and mitigating the effects of global warming, the electrochemical CO2 reduction reaction (CO2RR) powered by renewable sources and catalyzed by transition metal-based catalysts represents an attractive strategy to produce fuels and commodity chemicals. However, further improvement in the catalyst design is required to tackle the main bottlenecks that currently limit the performances of the state-of-the-art catalysts. Although several transition metal-based systems have been reported to catalyze CO2RR, catalyst durability and selectivity still represent major challenges to achieve an efficient CO2RR, mainly due to catalyst deactivation and to competitive Hydrogen evolution reaction (HER) and/or alternative pathways leading to multiple carbon-based products. The combination of molecular chemistry and heterogeneous catalysis has recently revealed to be an effective strategy to improve the overall efficiency and selectivity of the CO2RR process. In particular, the formation of hybrid catalysts based on the integration of organic molecules or reticular frameworks with heterogeneous metal or metal-oxide surfaces allowed to tune the stability of key reaction intermediates or the local microenvironment of the catalyst, resulting in a significant improvement of the CO2RR performances. In this contribution, we highlight a modular and versatile strategy to synthesize well-defined hybrid nanomaterials, based on the in situ growth of polymeric matrices around a well-defined metal nanoparticle core in a controlled manner. For instance, well-defined Cu2O nanocubes (NCs) are used as both templates and catalysts for an in situ polymerization based on a Cu-catalyzed azide–alkyne cycloaddition reaction (CuAAC) in the presence of the corresponding monomeric building blocks. This approach results in a series of hybrid nanoreactors with well-defined shape and size, which are active electrocatalysts for CO2 reduction in neutral-pH electrolyte. The composition of the molecular layer was found to be critical for the catalytic performances. The data herein presented provide a proof-of-concept of the potential offered by a molecular perspective towards a rational design of heterogeneous electrocatalysts

Electro- and Photoinduced Interfacial Charge Transfers in Nanocrystalline Mesoporous TiO2 and TiO2/Iron Porphyrin Sensitized Films under CO2 Reduction Catalysis

Electro-and photochemical CO2 reduction (CO2R) is the quintessence of modern-day sustainable research. We report our studies on the electro-and photoinduced interfacial charge transfer occurring in a nanocrystalline mesoporous TiO2 film and two TiO2/iron porphyrin hybrid films (meso-aryl-and beta-pyrrole-substituted porphyrins, respectively) under CO2R conditions. We used transient absorption spectroscopy (TAS) to demonstrate that, under 355 nm laser excitation and an applied voltage bias (0 to -0.8 V vs Ag/AgCl), the TiO2 film exhibited a diminution in the transient absorption (at -0.5 V by 35%), as well as a reduction of the lifetime of the photogenerated electrons (at -0.5 V by 50%) when the experiments were conducted under a CO2 atmosphere changing from inert N2. The TiO2/iron porphyrin films showed faster charge recombination kinetics, featuring 100-fold faster transient signal decays than that of the TiO2 film. The electro-, photo-, and photoelectrochemical CO2R performance of the TiO2 and TiO2/iron porphyrin films are evaluated within the bias range of -0.5 to -1.8 V vs Ag/AgCl. The bare TiO2 film produced CO and CH4 as well as H2, depending on the applied voltage bias. In contrast, the TiO2/iron porphyrin films showed the exclusive formation of CO (100% selectivity) under identical conditions. During the CO2R, a gain in the overpotential values is obtained under light irradiation conditions. This finding was indicative of a direct transfer of the photogenerated electrons from the film to absorbed CO2 molecules and an observed decrease in the decay of the TAS signals. In the TiO2/iron porphyrin films, we identified the interfacial charge recombination processes between the oxidized iron porphyrin and the electrons of the TiO2 conduction band. These competitive processes are considered to be responsible for the diminution of direct charge transfer between the film and the adsorbed CO2 molecules, explaining the moderate performances of the hybrid films for the CO2R

Facile synthesis of 9,10,19,20-tetraarylporphycenes

A simple route was developed for the synthesis of 9,10,19,20-tetraarylporphycenes by combining both McMurry and oxidative synthetic strategies and using readily available precursors. The desired 5,6-diaryldipyrroethenes, which were prepared in multigram quantities over two steps, were used to prepare 9,10,19,20-tetraarylporphycenes under mild acid-catalyzed conditions. As 5,6-diaryldipyrroethene precursors can easily be prepared in multigram quantities, this method is useful for the preparation of meso-tetrarylporphycenes that contain different aryl substituents. The molecular structures of these macrocycles were determined by HRMS analysis as well as 1D and 2D NMR studies. The tetraarylporphycenes exhibited a strong Soret band at approximately 380 nm and three Q bands in the region of 580–655 nm. The tetraarylprophycenes are reasonably fluorescent and stable under redox conditions

Lewis acid assisted decomplexation of F-BODIPYs to dipyrrins

A simple synthetic route was developed for the decomplexation of F-BODIPYs (fluorine-substituted boron–dipyrromethenes) to afford dipyrrins in high yields. This was achieved by treating the F-BODIPYs with different Lewis acids such as ZrCl4, TiCl4, AlCl3, Sc(OTf)3 or SnCl4 in CH3CN/CH3OH under refluxing conditions. This synthetic strategy was efficient for different types of F-BODIPYs such as meso-aryl-substituted BODIPYs, 3-pyrrolyl BODIPYs, functionalized 3-pyrrolyl BODIPYs, π-extended pyrrolyl BODIPYs, sterically crowded BODIPYs and the BF2 complex of 25-oxasmaragdyrin

Synthesis, Structure, and Catalytic Activity of Pd(II) Complex of Calixoxasmaragdyrin

The palladium­(II) complex of calixoxasmaragdyrin was prepared in 80% yield by treating the free base calixoxasmaragdyrin with PdCl₂ in CH₃CN at reflux temperature. The crystal structure solved for Pd­(II) calixoxasmaragdyrin indicates that the calixoxasmaragdyrin macrocycle is highly distorted and attained a boat shaped structure. The Pd­(II) ion is coordinated to four pyrrolic nitrogens in square planar fashion, and it is placed at ∼0.138 Å above from the four coordinating pyrrole nitrogens plane (N1N2N3N4). The Pd–N bond lengths are inequivalent, and the Pd­(II) ion is positioned more toward the dipyrromethane moiety of calixoxasmaragdyrin. The complex shows one broad absorption band at 477 nm and is not very stable under redox conditions. The Pd­(II) calixoxasmaragdyrin showed good catalytic activity in the Suzuki–Miyaura cross coupling reactions

β-meso covalently linked novel dipalladium(II) bis-dipyrrin complex

β-Meso covalently linked bis-dipyrrin ligand was synthesized by removing BF2 unit from β-dipyrrinyl BODIPY under mild Lewis acid catalyzed conditions and the resulted bis-dipyrrin ligand was used to prepare the first example of dipalladium(II) bis- dipyrrin complex by treating it with Pd(acac) 2 in CH2Cl2 at reflux temperature. The formation of dipalladium bis-dipyrrin complex was confirmed by HR-MS, 1D, 2D NMR spectroscopy and X-ray crystallography. The crystal structure revealed that both the Pd(II)-dipyrrin units are nonplanar and makes an angle of ∼59° with each other. The Pd(II) ions were slightly deviated from the dipyrrin plane and each Pd(II) ion was in square planar geometry co-ordinating to two nitrogen atoms of dipyrromethene unit and two oxygen atoms of acetylacetonate ligand. The preliminary studies indicated that dipalladium bis-dipyrrin complex can be used as efficient catalyst for Suzuki-Miyaura cross coupling reactions

β-meso covalently linked azaBODIPY-Pd(II) dipyrrin conjugate

The first example of azaBODIPY-metal dipyrrin conjugate such as covalently linked azaBODIPY-Pd(II) dipyrrin conjugate where the meso-carbon of Pd(II) dipyrrin moiety was linked to β-pyrrole carbon of azaBODIPY moiety was synthesized over sequence of facile steps under simple reaction conditions. The compound azaBODIPY-Pd(II) dipyrrin conjugate is freely soluble in common organic solvents and characterized by HR-MS, 1D & 2D NMR, X-ray crystallography, absorption, fluorescence and electrochemical techniques. The X-ray structure revealed that the azaBODIPY and Pd(II) dipyrrin moieties are almost orthogonal to each other with a dihedral angle of 80°. The spectral and electrochemical studies supported weak interaction between azaBODIPY and Pd(II) dipyrrin moieties in conjugate and marginally influences each other's electronic properties

Synthesis, structure and properties of core-modified pentaphyrins containing six meso carbons

Our successful synthesis of nonaromatic 24π core-modified pentaphyrins containing six meso carbons is reported. The pentaphyrins were prepared by [3+2] condensation of butane-2,3-diyl-bisthiophene-2,5-diyl-bis(p-methoxyphenylmethanol) with different meso-aryl tripyrromethanes under mild acid-catalyzed conditions. By using this method, we obtained two stable, core-modified pentaphyrins containing six meso carbons in acceptable yields. The pentaphyrins were characterized by HR-MS, 1D, 2D NMR, absorption and electrochemical techniques and also by X-ray crystallography for one of the pentaphyrin macrocycles. The crystal structure revealed that the macrocycle is almost planar and one of the thiophene rings, which is positioned opposite to the ethene bridged meso-carbons, is inverted. Our studies revealed that the macrocycles in their protonated form have specific sensing ability for CH3COO− ions