- Study on divalent copper, nickel and zinc model complexes for fluoride ion detection
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A series of new model complexes of 2,4-dihydroxybenzaldoxime (H3L) with divalent copper and nickel ions having a general formula [M(H2L)2]·sol (sol = solvent or nitrogen containing heterocycle) and a new zinc complex [Zn(H2L)2(pep)2] (where pep = 4-(2-(pyridine-4-yl)propyl)pyridine) were synthesized for the detection of fluoride ions. All complexes were structurally characterized by X-ray single crystal diffraction, powder X-ray diffraction and conventional spectroscopic tools. All these complexes show selective interactions with tetrabutylammonium fluoride. The position of the new UV-Vis absorption in each of these complexes in the presence of fluoride ions is guided by the electronic configuration of the metal ion. The complex [Zn(H2L)2(pep)2] has a distinct advantage over the other model complexes, as it can detect fluoride ions through both emission and absorption spectroscopy.
- Tarai, Arup,Baruah, Jubaraj B.
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- Synthesis, characterization and structural study of new vanadium complexes with phenolic oxime ligands
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In this work, three new vanadium complexes are reported. Their synthesis, crystallization and characterization are detailed. The complex (1) [VO(C7H6NO2)2] is a mononuclear and crystallizes in the monoclinic P21/n space group exhibiting a square pyramidal geometry around the vanadium. Dissolved in p-xylene (1–4 dimethylbenzene), this complex gives a binuclear complex (2) [V2O2(C7H6NO2)2(C7H5NO2)2]·C8H10 with a triclinic P-1 space group and an octahedral geometry around the vanadium. The complex (3) [VO2(C9H9N2O3)] was obtained using the new iminoacylated oxime ligand (the result of the nucleophilic attack of 4-hydroxysalicylaldoxime with acetonitrile), it crystallizes in the triclinic P-1 space group with a trigonal bipyramidal geometry around the vanadium. All complexes were characterized by single crystal X-ray diffraction, FT-IR, NMR, UV–visible and TGA.
- Belkhettab, Ilyas,Boutamine, Sultana,Slaouti, Hennia,Zid, Mohamed Faouzi,Boughzala, Habib,Hank, Zakia
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- Synthesis and SAR study of simple aryl oximes and nitrofuranyl derivatives with potent activity against Mycobacterium tuberculosis
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Background: Oximes and nitrofuranyl derivatives are particularly important compounds in medicinal chemistry. Thus, many researchers have been reported to possess antibacterial, antiparasitic, insecticidal and fungicidal activities. Methods: In this work, we report the synthesis and the biological activity against Mycobacterium tuberculosis H37RV of a series of fifty aryl oximes, ArCH=N-OH, I, and eight nitrofuranyl compounds, 2-nitrofuranyl-X, II. Results: Among the oximes, I: Ar = 2-OH-4-OH, 42, and I: Ar = 5-nitrofuranyl, 46, possessed the best activity at 3.74 and 32.0 μM, respectively. Also, 46, the nitrofuran compounds, II; X = MeO, 55, and II: X = NHCH2Ph, 58, (14.6 and 12.6 μM, respectively), exhibited excellent biological activities and were non-cytotoxic. Conclusion: The compound 55 showed a selectivity index of 9.85. Further antibacterial tests were performed with compound 55 which was inactive against Enterococcus faecalis, Klebisiella pneumonae, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhymurium and Shigel-la flexneri. This study adds important information to the rational design of new lead anti-TB drugs. Structure-activity Relationship (SAR) is reported.
- Calixto, Stephane Lima,Carvalho, Guilherme da Silva Louren?o,Coimbra, Elaine Soares,Granato, Juliana da Trindade,Louren?o, Maria Cristina da Silva,Wardell, James,da Costa, Cristiane Fran?a,de Souza, Marcus Vinicius Nora
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- METHOD FOR PREPARING BENZOIC ACID AMIDE COMPOUND
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The present invention relates to a method for preparing a benzoic acid amide compound in a high yield by presenting a novel method for preparing a benzyl amine compound to be used as a reactant and delimiting the reaction condition of each step by using the same, and the method is economically advantageous since mass production is possible.
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Paragraph 0104-0106
(2018/07/15)
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- Efficient symmetrical bidentate dioxime ligand-accelerated homogeneous palladium-catalyzed Suzuki-Miyaura coupling reactions of aryl chlorides
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A series of N,O-bidentate ligands were synthesized using the Vilsmeier-Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions. The coupling reactions were performed in the presence of PdCl2 as the catalyst, L8 as the ligand, Na2CO3 as the base, PEG-400 as the PTC and in ethanol/water (1?:?1) as an environmentally benign solvent at 85 °C. Plentiful biaryls were obtained by the optimized reaction with good yields at a low palladium loading of 0.20 mol%.
- Song, Jinyi,Zhao, Hongyan,Liu, Yang,Han, Huatao,Li, Zhuofei,Chu, Wenyi,Sun, Zhizhong
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supporting information
p. 372 - 376
(2016/12/30)
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- Discovery of phenoxybutanoic acid derivatives as potent endothelin antagonists with antihypertensive activity
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A series of phenoxybutanoic acid derivatives were synthesized and tested for their antagonistic activity on the contraction of the rat thoracic aortic ring induced by endothelin-1. Preliminary screening results showed that 6e and 6g with benzoheterocycles demonstrated significant antagonistic activities when compared to the reference compound BQ123. The results from additional assays for the binding affinity and selectivity for endothelin receptors showed that 6e was a selective ETA antagonist with a nanomolar IC50. Moreover, 6e was effective in relieving hypoxia-induced pulmonary arterial hypertension and right ventricular weight ratio. Therefore, 6e may have potential for further development as a therapeutic agent for the treatment of cardiovascular diseases.
- Cai, Jin,Liu, Ligang,Hong, Kwon Ho,Wang, Peng,Li, Lushen,Cao, Meng,Sun, Chunlong,Wu, Xiaoqing,Zong, Xi,Chen, Junqing,Ji, Min
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p. 657 - 667
(2015/02/19)
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- Hydrogen production on a hybrid photocatalytic system composed of ultrathin CdS nanosheets and a molecular nickel complex
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The production of clean and renewable hydrogen through water splitting by using solar energy has received much attention due to the increasing global energy demand. We report an economic and artificial photosynthetic system free of noble metals, consisting of ultrathin CdS nanosheets as a photosensitizer and nickelbased complex as a molecular catalyst. Emission quenching and flash photolysis studies reveal that this hybrid system allows for effective electron transfer from the excited CdS nanosheets to the nickel-based complex to generate reduced intermediate species for efficient hydrogen evolution. Notably, the unique morphological and structural features of the ultrathin CdS nanosheets contribute to the highly efficient photocatalytic performance. As a consequence, the resulting system shows exceptional activity and stability for photocatalytic hydrogen evolution in aqueous solution with a turnover number (TON) of about 28 000 versus catalyst and a lifetime of over 90 h under visible light irradiation.
- Xu, You,Yin, Xuguang,Huang, Yi,Du, Pingwu,Zhang, Bin
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supporting information
p. 4571 - 4575
(2015/03/18)
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- A study on fluoride detection and assembly of hydroxyaromatic aldoximes caused by tetrabutylammonium fluoride
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Tetrabutylammonium fluoride (TBAF) forms cocrystal H2NAP·TBAF with 2-hydroxynaphthaldoxime (H2NAP) or cocrystal 2(H3OHPA)·TBAF with 2,3-dihydroxyphenylaldoxime (H3OHPA), whereas a similar reaction with 2,4-dihydroxyphenylaldoxime (H3PHPA) forms tetrabutylammonium (TBA) salt TBA(H2.5PHPA)2. Formation of these cocrystals or salts is accompanied by a color change which enables the detection of fluoride ions. Cocrystal H2NAP·TBAF has a layered structure formed by hydrogen bonds between the fluoride ions and parent oxime molecules; the tetrabutylammonium cations are held in between layers of anionic assemblies. On the other hand, cocrystal 2(H3OHPA)·TBAF has a grid-like architecture constructed from hydrogen bonds between the parent oxime molecules and fluoride ions. TBA cations are encapsulated within the grids. It is shown that salt TBA(H2.5PHPA)2 forms anionic assemblies to encapsulate tetrabutylammonium cations which are devoid of fluoride ions. By interactions of the tetrabutylammonium fluoride ions with H3PHPA molecules, an anionic assembly is formed by the sharing of protons, which possesses a grid-like structure. The formation of such an assembly causes color change which enables one to detect fluoride ions by visual means. This journal is
- Tarai, Arup,Baruah, Jubaraj B.
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p. 2301 - 2309
(2015/03/14)
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- 4-cyanoresorcinol-based bent-core mesogens with azobenzene wings: Emergence of sterically stabilized polar order in liquid crystalline phases
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A new series of azobenzene containing bent-core molecules incorporating 4-cyanoresorcinol as the central core unit exhibiting cybotactic nematic, rectangular, columnar, and different types of tilted smectic (SmC) phases are synthesized. The mesophase behavior and phase structures are characterized in bulk and freely suspended films using a variety of experimental techniques. Depending on the chain length and temperature a series of different mesophases is observed in these compounds, ranging from cybotactic nematic via paraelectric SmC phases, polarization randomized SmCsPR phases to ferroelectric and antiferroelectric SmC phases, associated with increasing size and correlation length of the polar domains. Spontaneous formation of chiral domains is observed in the paraelectric SmC and the SmCsPR phases and discussed in relation with superstructural chirality, bend elastic constants, and surface effects. Development of polar order in tilted smectic liquid crystalline phases (SmC) of bent-core mesogens is found to take place with increasing polar domain size in a series of distinct phases via a paraelectric and a new randomized polar SmC phase (SmCsPR) to a ferroelectric phase, which then becomes modulated and finally changes to an antiferroelectric phase.
- Alaasar, Mohammed,Prehm, Marko,May, Kathrin,Eremin, Alexey,Tschierske, Carsten
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p. 1703 - 1717
(2014/04/03)
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- Effects of chain branching and chirality on liquid crystalline phases of bent-core molecules: Blue phases, de Vries transitions and switching of diastereomeric states
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Bent-core molecules based on a resorcinol bisbenzoate core with a series of distinct substituents in different positions at the central resorcinol core have been synthesized and characterized. The focus is on the effect of branched terminal groups in the racemic and chiral forms on the mesomorphic properties. These were investigated by differential scanning calorimetry, optical polarizing microscopy, X-ray diffraction, electro-optic and dielectric methods. Only bent-core mesogens derived from 4-cyanoresorcinol exhibit liquid crystalline phases and the mesophases of these compounds are strongly influenced by the branching and enantiomeric composition of the terminal chains. Depending on the structure of the rod-like wings and the enantiomeric composition, cybotactic nematic phases (NcybC), BPIII-like isotropic mesophases (BPIII cybC*) and various polar and apolar smectic phases (SmA, SmC, SmC*, SmCsPA, SmCsPA*) are formed. For one compound, a de Vries type smectic phase is observed and it appears that with decreasing temperature, order develops in two steps. First, at the SmA to SmC transition, the tilt direction becomes long range ordered and in a second step a long range ordering in bend direction takes place. Hence, for the optically active compound a transition from chirality induced polar switching to bend induced (shape induced) antiferroelectricity takes place. In this SmCsPA* phase a homogeneous layer chirality is induced under an applied electric field which interacts with the fixed molecular chirality leading to the energetically favoured diastereomeric state and giving rise to a field direction dependent uniform tilt director orientation. Field reversal induces a flipping of the layer chirality, which first leads to the less favorable diastereomeric state, and then this slowly relaxes to the more stable one by a spontaneous reversal of the tilt direction.
- Ocak, Hale,Bilgin-Eran, Belkiz,Prehm, Marko,Schymura, Stefan,Lagerwall, Jan P. F.,Tschierske, Carsten
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scheme or table
p. 8266 - 8280
(2012/03/10)
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- Development of polar order in liquid crystalline phases of a banana compound with a unique sequence of three orthogonal phases
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Alkyl substituted 4-cyanoresorcinol 1,3-bisbenzoates with terephthalate based rod-like wings show a series of three orthogonal smectic phases SmA-SmAPR-SmAPA.
- Keith, Christina,Prehm, Marko,Panarin, Yuri. P.,Vij, Jagdish K.,Tschierske, Carsten
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supporting information; scheme or table
p. 3702 - 3704
(2010/08/07)
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- Synthesis and tyrosinase inhibitory activity of novel N-hydroxybenzyl-N-nitrosohydroxylamines
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Several novel N-substituted N-nitrosohydroxylamines were synthesized. They all inhibited mushroom tyrosinase, but the type of inhibition was different depending on the substituent. Some N-(mono- or dihydroxybenzyl)-N-nitrosohydroxylamines exhibited uncompetitive inhibition with respect to L-dopa. Among them, compound 6 was also a competitive inhibitor with respect to oxygen. This observation suggests that another interaction by the meta- or para-hydroxyl group might stabilize the binding of the inhibitor to the enzyme through the oxygen binding site.
- Shiino, Mitsuhiro,Watanabe, Yumi,Umezawa, Kazuo
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p. 129 - 135
(2007/10/03)
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- Use of Nitrile Oxides in Synthesis. A Novel Synthesis of Chalcones, Flavanones, Flavones and Isoflavones
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Novel methodology is developed for a three-step synthesis of chalcones, flavanones, flavones and isoflavones. 1.Salicylaldoxime is chlorinated to the corresponding hydroxamoyl chloride in the presence of pyridine, and cycloadded to styrene and phenylacetylene. 2.The isoxazole derivatives formed are reductively cleaved over Raney-Ni to β-hydroxyketones or 1,3 diketones. 3.Acid-catalyzed cyclization gives the flavonoids.Use of ω-methoxy- or ω-dialkylamino-substituted styrenes (enamines) leads regioselectively to 4-aryl-substituted isoxazoles and derived isoflavones.
- Thomsen, Ib,Torssell, Kurt B. G.
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p. 303 - 308
(2007/10/02)
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