- Effect of substituents on the UV spectra of supermolecular system: Silver nanoparticles with bi-aryl Schiff bases containing hydroxyl
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Effect of substituents on the ultraviolet (UV) spectra of supermolecular system involving silver nanoparticles (AgNPs) and Schiff bases was investigated. AgNPs and 49 samples of model compounds (MC), bi-aryl Schiff bases containing hydroxyl (XBAY, involving 4-OHArCH?NArY, 2-OHArCH?NArY, XArCH?NAr-4′-OH, and XArCH?NAr-2′-OH), were synthesized. The size of AgNPs was characterized by transmission electron microscopy (TEM), and the UV absorption spectra of AgNPs, XBAYs, and MC-AgNPs mixed solutions were measured, respectively. The results show that (1) the size of AgNPs is larger in MC-AgNPs solutions than that in AgNPs solution due to the distribution of MC molecules on the surface of AgNPs; (2) the UV absorption wavelength of XBAYs changes in the action of AgNPs and their wavelength shift exists limitation between XBAY and MC-AgNPs solutions; and (3) the wavelength shift limit of MC-AgNPs (λWSL) is influenced by the substituents X and Y and the position of hydroxyl OH. The wavenumber ΔνWSL of λWSL can be quantified by employing the excited-state substituent constant σexCC and Hammett constant σ of substituents X and Y. Comparing with the 4-OH, the 4′-OH makes the ΔνWSL a red shift, whereas the 2′-OH, comparing with the 2-OH, makes the ΔνWSL a blue shift.
- Cao, Chao-Tun,Cheng, Shimao,Zhang, Jingyuan,Cao, Chenzhong
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- Synthesis, structure and catalytic alcohol oxidation by ruthenium(III) supported by Schiff base and triphenylphosphine ligands
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Treatment of [RuCl2(PPh3)3] with two equiv. bi-dentate Schiff base N,O-LH-Cl (N,O-LH-Cl = 2[(3-chloro-phenylimino)-methyl]-phenol) or N,O-LH-NO2 (N,O-LH-NO2 = 2[(4-nitro-phenylimino)-methyl]-phenol) in the presence of triethylamine afforded cis-[RuCl(PPh3)(κ2-N,O-L-Cl)2] (1) and trans-[RuCl(PPh3)(κ2-N,O-L-NO2)2]·Et2O (2), respectively. Reactions of [RuCl2(PPh3)3] and equal equiv. tetra-dentate Schiff bases gave corresponding ruthenium(III) complexes [RuCl(PPh3)(salen)] (3) (H2salen = N,N′-disalicylidene-1,2-ethanediamine), [RuCl(PPh3)(salipn)]·2CH2Cl2 (4) (H2salipn = N,N′-disalicylidene-1,2-(1-methyl)ethanediamine), [RuCl(PPh3)(salpn)]·CH2Cl2 (5) (H2salpn = N,N′-disalicylidene-1,2-propanediamine), [RuCl(PPh3)(salphen)]·CH2Cl2 (6) (H2salphen = N,N′-disalicylidene-1,2-phenyldiamine), [RuCl(PPh3)(saltoln)]·CH2Cl2 (7) (H2saltoln = N,N′-disalicylidene-1,2-tolyldiamine) and [RuCl(PPh3)(salcyn)] (8) (H2salcyn = N,N′-disalicylidene-(R,R)-1,2-cyclohexanediamine). The molecular structures of complexes 1–5 and 7 have been determined by single-crystal X-ray crystallography. The catalytic oxidation properties of ruthenium(III) complexes 1–8 were tested towards alcohols in the presence of N-methylmorpholine-N-oxide.
- Tang, Li-Hua,Wu, Fule,Lin, Hui,Jia, Ai-Quan,Zhang, Qian-Feng
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p. 212 - 218
(2018/04/02)
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- Syntheses and crystal structures of ruthenium complexes with bidentate salicylaldiminato and dithiophosphato ligands
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Treatment of the bidentate Schiff base 2-[(2,6-diisopropyl-phenylimino)-methyl]-phenol (HL1) with one equivalent of (Et4N)[RuCl4(MeCN)2] in the presence of triethylamine afforded (Et4N)[RuCl3(κ2
- Tang, Li-Hua,Wu, Fule,Lin, Hui,Jia, Ai-Quan,Zhang, Qian-Feng
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p. 329 - 335
(2018/05/22)
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- Palladium-Catalyzed Regioselective C-Benzylation via a Rearrangement Reaction: Access to Benzyl-Substituted Anilines
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An unprecedented C-benzylation rearrangement reaction, catalyzed by palladium, is reported. The reaction proceeds by rearrangement leading to the direct synthesis of para or ortho benzyl-substituted N-methylanilines. The product is obtained in high regioselectivity, without the need to use a ligand for the catalytic process.
- Amézquita-Valencia, Manuel,Alper, Howard
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supporting information
p. 16774 - 16778
(2016/11/17)
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- Halide substituted Schiff-bases: Different activities in methyltrioxorhenium(VII) catalyzed epoxidation via different substitution patterns
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This report shows the influence of halide substituted Schiff-bases as ligands of methyltrioxorhenium (MTO) in epoxidation catalysis. Therefore, selected Schiff-bases were prepared by the reaction of hydroxy-benzaldehydes and aniline derivates. These differently substituted Schiff-bases were tested as MTO-ligands in cyclooctene-and 1-octene-epoxidation. Although no great disparities among the substitution patterns have been found, some conclusions can be drawn. Flourines are inferior to chlorines or bromines as substituents. Halides in ortho-position lead to higher activities than in para-or meta-position. The balance between electron donating and withdrawing influences at the Schiff-base plays a prominent role in their utility as ligand to MTO in epoxidation catalysis.
- Altmann, Philipp,Cokoja, Mirza,Kühn, Fritz E.
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experimental part
p. 51 - 55
(2012/03/11)
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- Factors determining tautomeric equilibria in Schiff bases
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Schiff bases derived from o-hydroxyaldehydes present keto and enol tautomeric forms; the relative equilibrium between these two tautomers depending on the particular aldehyde the Schiff bases is derived from. Thus benzaldehyde produces a stable enol tauto
- Flores-Leonar, Martha,Esturau-Escofet, Nuria,Méndez-Stivalet, José M.,Marín-Becerra, Armando,Amador-Bedolla, Carlos
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experimental part
p. 600 - 605
(2012/02/03)
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- Methyltrioxorhenium-catalyzed oxidation of pseudocumene for vitamin e synthesis: A study of solvent and ligand effects
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Vitamin E is an essential food component of major economical relevance with important antioxidant properties and biological activity. The oxidation of pseudocumene to trimethyl-1,4-benzoquinone would be a key transformation in an alternative industrial production of α-tocopherol that is important for the antioxidant activity of vitamin E. The methyltrioxorhenium (MTO)-catalyzed oxidation of pseudocumene has been revisited to offer a more environmentally friendly, economically beneficial and milder approach to this important industrial product. It has been observed that by choosing the solvent and Lewis base additives (as ligands of MTO), both yield and chemoselectivity are considerably improved, allowing milder reaction conditions compared to previously reported protocols.
- Carril, Monica,Altmann, Philipp,Drees, Markus,Bonrath, Werner,Netscher, Thomas,Schuetz, Jan,Kuehn, Fritz E.
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experimental part
p. 55 - 67
(2011/11/30)
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- Synthesis, crystal structure and electronic properties of bis(N-2-bromophenyl-salicydenaminato)copper(II) complex
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A new series of complexes of the type bis(N-substituted-salicydenaminato)copper(II) (1-9), have been synthesized and characterized by IR, UV-Vis and elemental analysis methods. The molecular structure of bis(N-2-bromophenyl-salicydenaminato)copper(II) (6)
- Vafazadeh, Rasoul,Hayeri, Vahid,Willis, Anthony C.
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experimental part
p. 1810 - 1814
(2010/07/04)
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- Synthesis and antifungal activity of some new 1, 2-benzisoxazole
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Various 3H-N-substituted phenyl / thiazolyl 1,2-benzisoxazole have been synthesized by the reaction of schiffs base with DMSO-I2 in presence of H2SO4 and characterized by IR,NMR spectral studies and elemental analysis. These compounds showed significant activities against plant pathogenic fungi viz. Alterneria burnsii and Macrophomina phasiolina.
- Sareen,Khatri,Shinde,Chugh,Sareen
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experimental part
p. 33 - 34
(2011/06/21)
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- Synthesis and spectral characterization of N-[2-(4-halophenoxy)-3-(3- chlorophenyl)-3, 4-dihydro-2H-1,3,2-Λ5-benzoxazaphosphinin-2- yliden]-N-substituted amines by the Staudinger reaction
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The synthesis of the title compounds was accomplished in four steps. The synthetic route involves the preparation of Schiff's base by reacting salicylaldehyde with m-chloroaniline in EtOH. The Schiff's base was then reduced with NaBH4/MeOH. In the second step, PCl3 was reacted with p-chlorophenol/p-bromophenol in THF in the presence of Et3N to obtain P(III) dichloride derivatives. The reduced Schiff's base and dichloride derivatives were reacted in equimolar quantities in the presence of Et 3N in THF to get the cyclized product. Alkyl azides were prepared by reacting alkyl bromides with sodium azide, and then alkyl azides were treated with the cyclized product to obtain the title compounds. The structure of these novel compounds was elucidated by elemental analysis, IR, 1H, 13C, 31P NMR, and mass spectroscopy.
- Venkateswarlu,Satyanarayana,Rao, C. V. Nageswara,Naidu, K. Reddy Mohan,Raju, C. Naga
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scheme or table
p. 499 - 504
(2011/08/02)
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- Nonlinear optical properties of some derivatives of salicylaldimine-based ligands
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A series of potential nonlinear optical (NLO) compounds, (-OH) and (-Cl) substituted derivatives of salicylaldimine-based ligands 1-6 (Fig. 2), was designed and synthesized. Compounds 1 and 2 were characterized by X-ray diffraction analysis, elemental analysis, IR, 1H-NMR, 13C-NMR and UV-Visible spectroscopies. The electric dipole moments (μ) and the first hyperpolarizabilities (β) of the compounds 1-6 were calculated using ab-initio quantum calculations (finite field M?ller Plesset perturbation theory). The calculation results reveal that the substituent positions play a significant role in NLO properties of these compounds.
- Karaka?,Elmali,ünver,Svoboda
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p. 103 - 110
(2007/10/03)
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- Study of Formation Constants of Substituted Salicylanils and 2'-Hydroxysalicylanils
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The proton-ligand stability constants of some substituted salicylanils and 2'-hydroxy-salicylanils have been studied by the Bjerrum-Calvin pH titration technique in water-dioxane medium (1:3 v/v) at μ ca. 0.1 (NaClO4) and at 30 deg C (+/-0.1).The results
- Dodwad, S.S.,Patil, Indira,Datar, M.G.
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p. 595 - 597
(2007/10/02)
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- Study of Uranyl Complexes of Some Schiff Bases
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Dioxouranium(VI) complexes of some Schiff bases, obtained by condensing chloroanilines and toluidines with salicylaldehyde are synthesised and characterised by elemental analysis, spectral and conductance data.All the complexes are orange red in colour, m
- Prabhu, P. S.,Dodwad, S. S.
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p. 546 - 549
(2007/10/02)
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- Benzylideneaniline derivatives
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This invention describes a method of treating inflammation in warm blooded animals by topically administering an effective amount of benzylideneaniline or its derivatives.
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