1228273-66-2Relevant academic research and scientific papers
Porous organic cage stabilised palladium nanoparticles: Efficient heterogeneous catalysts for carbonylation reaction of aryl halides
Zhang, Yong,Xiong, Yu,Ge, Jin,Lin, Rui,Chen, Chen,Peng, Qing,Wang, Dingsheng,Li, Yadong
, p. 2796 - 2799 (2018)
Porous organic cage stabilised palladium nanoparticles were successfully prepared using methanol as a mild reductant. The as-prepared porous composite materials show high catalytic activity for the carbonylation reaction of aryl halides under mild conditions.
Syntheses, Crystal Structures, and Spectral Characterization of Six Novel Benzimidazolyl Substituted Triaryltriazoles
Zhou, Yong-Fei,Zhang, Shi-Pei,Feng, Zhe,Shen, Xuan,Zhu, Dun-Ru
, p. 2773 - 2780 (2017)
Six new benzimidazolyl substituted triaryltriazoles, 3-(2-pyridyl)-4-(p-R-phenyl)-5-(2-benzimidazolyl)-1,2,4-triazoles (L1: R?=?OCH3; L2: R?=?CH3; L3: R?=?H; L4: R?=?Br; L5: R?=?Cl; L6: R?=?F) were successfully synthesized. Yield of L1–6 is in the range from 61 to 76%. The compounds L1–6 were characterized by UV–vis, FTIR, 1H-NMR, ESI-MS spectra, and elemental analysis. Additionally, the absolute configurations of L1–5 were determined by single crystal X-ray crystallography.
Photolysis and thermolysis of pyridyl carbonyl azide monolayers on single-crystal platinum
Adkinson, Dana K.,Magri, David C.,Pitters, Jason L.,Griffiths, Keith,Norton, Peter R.,Workentin, Mark S.
, p. 1020 - 1028 (2013)
The photochemical and thermal reactivity of a number of acyl azide-substituted pyridine compounds, namely nicotinyl azide, isonicotinyl azide, picolinyl azide and dinicotinyl azide with investigated as saturated monolayers on a single-crystal Pt(111) surface in an ultrahigh vacuum chamber. Multilayers of the substrates exhibited a maximum rate of desorption at 270 K, above which, stable saturated monolayers formed as characterized by reflection-absorption infrared spectroscopy by observation of C=O and N 3 bands at 1700 cm-1, and 2100 and 1300 cm-1 respectively. The monolayers were stable up to 400 K. Photolysis of the monolayer (or heating above 400 K) results in the formation of the respective isocyanate intermediate after loss of nitrogen as evidenced by the appearance of a new infrared band at 2260 cm-1 with concomitant loss of the azide bands. The resulting isocyanate saturated monolayer is stable in absence of nucleophiles, but can be quenched with appropriate nucleophiles. Saturated monolayers of a number of acyl azide-substituted pyridine compounds, namely nicotinyl azide, isonicotinyl azide, picolinyl azide and dinicotinyl azide, were formed on single-crystal Pt(111) surfaces in a UHV chamber. These monolayers were characterized by RAIR and thermal programmed desorption. Photolysis or thermolysis of these saturated monolayers leads to the corresponding isocyanate via a Curtius rearrangement.
Selective Extraction of Americium(III) over Europium(III) Ions with Pyridylpyrazole Ligands: Structure–Property Relationships
Su, Dongping,Liu, Ying,Li, Shimeng,Ding, Songdong,Jin, Yongdong,Wang, Zhipeng,Hu, Xiaoyang,Zhang, Lirong
, p. 651 - 658 (2017)
To clarify the structure–property relationships of pyridylpyrazole ligands and provide guidance for the design of new and more efficient ligands for the selective extraction of actinides over lanthanides, a series of alkyl-substituted pyridylpyrazole ligands with different branched chains at different positions of the pyrazole ring were synthesized. Extraction experiments showed that the pyridylpyrazole ligands exhibited good selective extraction abilities for AmIIIions, and the steric effects of the branched chain had a significant impact on the distribution ratios of AmIIIand EuIIIions as well as the separation factor. Moreover, both slope analyses and UV/Vis spectrometry titrations indicated the formation of a 1:1 complex of 2-(1-octyl-1H-pyrazol-3-yl)pyridine (C8-PypzH) with EuIIIions. The stability constant (log K) for this complex obtained from the UV/Vis titration was 4.45 ± 0.04. Single crystals of the complexes of 3-(2-pyridyl)pyrazole (PypzH) with Eu(NO3)3and Sm(NO3)3were obtained; PypzH acts as a bidentate ligand in the crystal structures, and the N atom with a bound H atom did not participate in the coordination. In general, this study revealed some interesting findings on the effects of the alkyl-chain structure and the special complexation between pyridylpyrazole ligands and LnIIIions.
Divalent Metal Ion Catalysis in the Hydrolysis of Esters of Picolinic Acid. Metal Ion Promoted Hydroxide Ion and Water Catalyzed Reactions
Fife, Thomas H.,Przystas, Theodore J.
, p. 1041 - 1048 (1985)
Rate constants have been determined for hydrolysis of a series of phenolic and aliphatic esters of picolinic acid in H2O.Hydroxide ion, hydronium ion, and water catalyzed reactions were observed in hydrolysis of the phenolic esters.Catalysis by low concentrations of Ni2+ and Cu2+ occurs even though binding of the metal ions is weak (saturation effects were not observed).Both metal ion promoted water and OH- catalyzed reactions were observed with the esters having leaving groups with pKa values of 12.4 or less.Rate enhancements produced by 0.01 M Ni2+ and 0.001 M Cu2+ range from 10- to near 200-fold in the pH-independent water reactions and from 102- to over 105-fold in the OH- catalyzed reactions.Significant metal ion catalysis was not observed in the hydrolysis of 4-nitrophenyl isonicotinate or 8-(5-nitroquinolyl) isonicotinate; therefore, metal ion catalysis in the hydrolysis of the esters with the pyridine nitrogen ortho to the ester function must be associated with a chelation effect.The rate constants k0 and kOH for hydrolysis of the picolinate esters in the metal ion promoted water and OH- catalyzed reactions are little affected by the leaving group (β1g ca. 0) for leaving groups with pKa values ranging from 4.1 with 2,4-dinitrophenol to 12.4 with trifluoroethanol, and ratios of kOH/k0 are nearly constant.This indicates that there is little or no C-O bond breaking in the critical transition state, i.e., in both reactions the nucleophilic attack step is rate determining.When the leaving group is ethanol, then kOH is markedly less than in the case of the trifluoroethyl ester, and a metal ion promoted water reaction is not detected even at pH values as low as 4.Thus, a change in rate-determining step has occurred with the change in the leaving group.Likewise only metal ion promoted OH- catalysis is observed with ethyl 6-carboxypicolinate.Rate enhancements produced by saturating concentrations of Ni2+ and Cu2+ are in that the case 2.7*104- and 1.3*105-fold, respectively.Intramolecular general base catalysis does not occur in the metal ion promoted water reaction of 8-quinolyl picolinate or 8-(5-nitroquinolyl) picolinate.With the nitro substituted esters of picolinic acid a metal ion promoted formate and acetate ions are attacking the metal ion complexes as nucleophiles.
Pleuromutilin derivative with 1, 3, 4-oxadiazole side chain and preparation and application thereof
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Paragraph 0055-0056; 0070; 0090; 0092; 0095; 0102, (2021/07/24)
The invention belongs to the field of medicinal chemistry, and particularly relates to a pleuromutilin derivative with a 1, 3, 4-oxadiazole side chain and preparation and application thereof The pleuromutilin derivative with the 1, 3, 4-oxadiazole side chain is a compound shown in a formula 2 or a pharmaceutically acceptable salt thereof, and a solvent compound, an enantiomer, a diastereoisomer and a tautomer of the compound shown in the formula 2 or the pharmaceutically acceptable salt thereof or a mixture of the solvent compound, the enantiomer, the diastereoisomer and the tautomer in any proportion, including a racemic mixture. The pleuromutilin derivative has good antibacterial activity, is especially suitable for being used as a novel antibacterial agent for systemic system infection of animals or human beings, and has good water solubility.
Homarine Alkyl Ester Derivatives as Promising Acetylcholinesterase Inhibitors
Jo?o, Karen G.,Videira, Romeu A.,Paiva-Martins, Fátima,Valent?o, Patrícia,Pereira, David M.,Andrade, Paula B.
, p. 3315 - 3325 (2021/08/30)
Reversible acetylcholinesterase (AChE) inhibitors are key therapeutic tools to modulate the cholinergic connectivity compromised in several degenerative pathologies. In this work, four alkyl esters of homarine were synthesized and screened by using Electrophorus electricus AChE and rat brain AChE-rich fraction. Results showed that all homarine alkyl esters are able to inhibit AChE by a competitive inhibition mode. The effectiveness of AChE inhibition increases with the alkyl side chain length of the homarine esters, being HO?C16 (IC50=7.57±3.32 μM and Ki=18.96±2.28 μM) the most potent inhibitor. The fluorescence quenching studies confirmed that HO?C16 is the compound with higher selectivity and affinity for the tryptophan residues in the catalytic active site of AChE. Preliminary cell viability studies showed that homarine esters display no toxicity for human neuronal SH-SY5Y cells. Thus, the long-chain homarine esters emerge as new anti-cholinesterase agents, with potential to be considered for therapeutic applications development.
Design, synthesis, in vitro and in vivo evaluation against MRSA and molecular docking studies of novel pleuromutilin derivatives bearing 1, 3, 4-oxadiazole linker
Liu, Jie,Zhang, Guang-Yu,Zhang, Zhe,Li, Bo,Chai, Fei,Wang, Qi,Zhou, Zi-Dan,Xu, Ling-Ling,Wang, Shou-Kai,Jin, Zhen,Tang, You-Zhi
, (2021/05/17)
A class of pleuromutilin derivatives containing 1, 3, 4-oxadiazole were designed and synthesized as potential antibacterial agents against Methicillin-resistant staphylococcus aureus (MRSA). The ultrasound-assisted reaction was proposed as a green chemistry method to synthesize 1, 3, 4-oxadiazole derivatives (intermediates 85–110). Among these pleuromutilin derivatives, compound 133 was found to be the strongest antibacterial derivative against MRSA (MIC = 0.125 μg/mL). Furthermore, the result of the time-kill curves displayed that compound 133 could inhibit the growth of MRSA in vitro quickly (- 4.36 log10 CFU/mL reduction). Then, compound 133 (- 1.82 log10 CFU/mL) displayed superior in vivo antibacterial efficacy than tiamulin (- 0.82 log10 CFU/mL) in reducing MRSA load in mice thigh model. Besides, compound 133 exhibited low cytotoxicity to RAW 264.7 cells. Molecular docking studies revealed that compound 133 was successfully localized in the binding pocket of 50S ribosomal subunit (ΔGb = -10.50 kcal/mol). The results indicated that these pleuromutilin derivatives containing 1, 3, 4-oxadiazole might be further developed into novel antibiotics against MRSA.
4-Amino-1,2,4-triazole-3-thione-derived Schiff bases as metallo-β-lactamase inhibitors
Baud, Damien,Bebrone, Carine,Becker, Katja,Benvenuti, Manuela,Cerboni, Giulia,Chelini, Giulia,Cutolo, Giuliano,De Luca, Filomena,Docquier, Jean-Denis,Feller, Georges,Fischer, Marina,Galleni, Moreno,Gavara, Laurent,Gresh, Nohad,Kwapien, Karolina,Legru, Alice,Mangani, Stefano,Mercuri, Paola,Pozzi, Cecilia,Sannio, Filomena,Sevaille, Laurent,Tanfoni, Silvia,Verdirosa, Federica,Berthomieu, Dorothée,Bestgen, Beno?t,Frère, Jean-Marie,Hernandez, Jean-Fran?ois
supporting information, (2020/09/16)
Resistance to β-lactam antibiotics in Gram-negatives producing metallo-β-lactamases (MBLs) represents a major medical threat and there is an extremely urgent need to develop clinically useful inhibitors. We previously reported the original binding mode of 5-substituted-4-amino/H-1,2,4-triazole-3-thione compounds in the catalytic site of an MBL. Moreover, we showed that, although moderately potent, they represented a promising basis for the development of broad-spectrum MBL inhibitors. Here, we synthesized and characterized a large number of 4-amino-1,2,4-triazole-3-thione-derived Schiff bases. Compared to the previous series, the presence of an aryl moiety at position 4 afforded an average 10-fold increase in potency. Among 90 synthetic compounds, more than half inhibited at least one of the six tested MBLs (L1, VIM-4, VIM-2, NDM-1, IMP-1, CphA) with Ki values in the μM to sub-μM range. Several were broad-spectrum inhibitors, also inhibiting the most clinically relevant VIM-2 and NDM-1. Active compounds generally contained halogenated, bicyclic aryl or phenolic moieties at position 5, and one substituent among o-benzoic, 2,4-dihydroxyphenyl, p-benzyloxyphenyl or 3-(m-benzoyl)-phenyl at position 4. The crystallographic structure of VIM-2 in complex with an inhibitor showed the expected binding between the triazole-thione moiety and the dinuclear centre and also revealed a network of interactions involving Phe61, Tyr67, Trp87 and the conserved Asn233. Microbiological analysis suggested that the potentiation activity of the compounds was limited by poor outer membrane penetration or efflux. This was supported by the ability of one compound to restore the susceptibility of an NDM-1-producing E. coli clinical strain toward several β-lactams in the presence only of a sub-inhibitory concentration of colistin, a permeabilizing agent. Finally, some compounds were tested against the structurally similar di-zinc human glyoxalase II and found weaker inhibitors of the latter enzyme, thus showing a promising selectivity towards MBLs.
Lanthanoid pyridyl-β-diketonate 'triangles'. New examples of single molecule toroics
Caporale, Chiara,Fuller, Rebecca O.,Massi, Massimiliano,Murray, Keith S.,Ogden, Mark I.,Phonsri, Wasinee,Rajaraman, Gopalan,Sobolev, Alexandre N.,Swain, Abinash
supporting information, p. 17421 - 17432 (2020/12/28)
Trinuclear lanthanoid clusters have been synthesised and investigated as toroidal spin systems. A pyridyl functionalised β-diketonate, 1,3-bis(pyridin-2-yl)propane-1,3-dione (o-dppdH) has been used to synthesise a family of clusters of the form [Dy3(OH)2(o-dppd)3Cl2(H2O)4]Cl2·7H2O (1), [Tb3(o-dppd)3(μ3-OH)2(CH3CH2OH)3Cl3][Tb3(o-dppd)3(μ3-OH)2(H2O)(CH3CH2OH)2Cl3]Cl2·H2O (2), [Ho3(OH)2(o-dppd)3Cl(H2O)5]Cl3·3H2O (3) and [Er3(OH)2(o-dppd)3Cl2(H2O)3(CH3OH)]Cl2·3H2O·CH3OH (4). Despite the previous occurrence of this structural motif in the literature, these systems have not been widely investigated in terms of torodic behaviour. Magnetic studies were used to further characterise the complexes. DC susceptibility studies support weak antiferromagnetic exchange in the complexes. Slow magnetic relaxation behaviour is observed in the dynamic AC magnetic studies for complex 1. Theoretical studies predict that complex 1 and 3 have a non-magnetic ground state based on a toroidal arrangement of spins. Changes to the coordination environment in 2 do not support a toroic spin state. The prolate nature of the ErIII centres in complex 4 and large transverse anisotropy do not support the toroidal arrangement of lanthanoid spins in the complex.
