2466-76-4Relevant articles and documents
Silica Subsurface Amine Effect on the Chemical Stability and Chromatographic Properties of End-Capped Immobilized Artificial Membrane Surfaces
Invergo, Ben,Alvarez, Francisco M.
, p. 1851 - 1860 (1991)
The silica surface of immobilized artificial membranes containing phosphatidylcholine (IAM.PC) has approximately two aminopropyl groups per immobilized phosphatidylcholine molecule.Primary amines near the silica subsurface adsorb biomolecules and also decrease the chemical stability of IAM.PC surfaces.Consequently, subsurface amines were end-capped by several methods including silylating reagents, acetyl analogues, glycidol, methyl glycolate, short-chain anhydrides (3-6 carbons/anhydride chain), and long-chain anhydrides (10-12 carbons/anhydride chain).All end-capping reactions resulted in loss of the initially immobilized phosphatidylcholine molecule.However, the amount of PC loss during end capping was very low (for alkyl anhydride end-capping reactions).After end capping, IAM.PC showed increased chemical stability compared to non end-capped IAM.PC surfaces.The chemical stability of IAM packing material was monitored by phospholipid leaching from IAM surfaces exposed to organic and aqeous solvents using thin-layer chromatography, 1H-NMR spectroscopy, infrared spectroscopy, and mass spectroscopy.IAM.PC packing material end capped with long-chain anhydrides exhibited the greatest chemical stability, i. e., little or no detectable phospholipid leaching when challenged with aqueous and/or organic solvents.The chromatography of acidic and basic compounds of end-capped and non end-capped IAM.PC surfaces was studied.Compared to non end-capped IAM.PC HPLC columns, the chromatographic retention times of acidic compounds (deoxynucleotides) decreased after end caping.In contrast, the retention times of basic compounds (amphetamine analogues) increased on end-capped IAM.PC HPLC columns.This indicates that these solutes have access to the silica subsurface amine during chromatography.
Differentiation of Nucleophilic and General Base Catalysis in the Hydrolysis of N-Acetylbenzotriazole Using the Proton Inventory Technique
Gopalakrishnan, Ganesa,Hogg, John L.
, p. 4959 - 4964 (1981)
The hydrolysis of N-acetylbenzotriazole is catalyzed by acetate and imidazole by two different modes as shown by the proton inventory technique.Acetate acts as a general base catalyst to abstract a proton from the attacking water molecule.The unexpected upward curvature in the proton inventory plot can be attributed to a reactant-state isotopic fractionation factor contribution from acetate ion.The proton inventory for imidazole catalysis exhibits downward curvature and is shown to be consistent with a nucleophilic catalyses role for imidazole.The intermediate, 1-acetylimidazole, then undergoes rate-determining water-catalyzed hydrolysis via the expected mechanism.
Synthesis, characterization and spectroscopic studies of two new 1-acetyl-3-alkylimidazolium ionic liquids
Huanhuan, Xu,Wenjuan, Zhu,Pingmei, Wang,Dafei, Wang,Qiang, Li
, p. 179 - 181 (2013)
Two new functionalized ionic liquids, 1-acetyl-3-alkylimidazolium iodides, were synthesized by the reactions of 1-acetylimidazole with alkyl iodides under solvent-free condition. Their structures were confirmed by 1H NMR, ESI-MS, IR, UV-Vis and elemental analysis. The 1-acetyl-3-ethylimidazolium iodide (3a) is a solid and 1-acetyl-3-hexylimidazolium iodide (3b) is a viscous liquid at room temperature.
DNA AFFINITY CLEAVING SEQUENCE SPECIFIC CLEAVAGE OF DNA BY DISTAMYCIN-EDTA*Fe(II) AND EDTA-DISTAMYCIN*Fe(II)
Taylor, John S.,Schultz, Peter G.,Dervan, Peter B.
, p. 457 - 465 (1984)
The attachment of EDTA*Fe(II) to distamycin changes the sequence specific DNA binding antibiotic into a sequence specific DNA cleaving molecule.We report the synthesis of EDTA-distamycin (ED) which has the metal chelator, EDTA, tethered to the carboxy terminus of the N-methylpyrrole tripeptide moiety of the antibiotic, distamycin.EDTA-distamycin*Fe(II) (ED*Fe(II)) at 1E-6M concentration efficiently cleaves pBR322 DNA (1E-5M in base pairs) in the presence of oxygen and dithiothreitol (DTT).Using Maxam-Gilbert sequencing gel analyses, we find that ED*Fe(II) affords DNA cleavage patterns of unequal intensity covering two to four contiguous base pairs adjacent to a five base pair site consisting of adenines (A) and thymines (T).The multiple cleavages at each site might be evidence for a diffusible oxidizing species, perhaps hydroxyl radical.The unequal intensity of cleavage on each side of the A + T site permit assignment of major and minor orientations of the tripeptide binding unit.A comparison of the cleavage specificity of ED*Fe(II) with distamycin-EDTA*Fe(II), (DE*Fe(II)) which has EDTA*Fe(II) attached to the amino terminus of the N-methylpyrrole tripeptide, shows DNA cleavage patterns at the same sites but with intensities of opposite polarity.Maxam-Gilbert sequencing gel analysis of the DNA cleavage patterns by ED*Fe(II) and DE*Fe(II) on both DNA strands of a 381 base pair restriction fragment reveals asymmetric DNA cleavage patterns.Cleavage is shifted to the 3' side of each DNA strand.A model consistent with this cleavage pattern indicates one preferred binding site for ED*Fe(II) and DE*Fe(II) is 3'-TTTAA-5' with the "amino end" of the tripeptide oriented to the 3' end of the thyamine rich strand.This "DNA affinity cleavage" method which consists of attaching cleaving functions to DNA binding molecules followed by DNA cleavage pattern analyses using Maxam-Gilbert sequencing gels may be a useful direct method for determining the binding site and orientation of small molecules on native DNA.
An efficient catalytic method for the c-n acylation of heterocycles by schiff base co(Ii), ni(ii), cu(ii) and zn(ii) transition metal complexes
Hegade, Sujit,Gaikwad, Gautam,Jadhav, Yuvraj,Chavan, Sanjay,Mulik, Ganpatrao
, p. 611 - 616 (2021/09/30)
The catalytic activity of Schiff base Co(II), Ni(II), Cu(II) and Zn(II) transition metal complexes was tested for N-Acylation of heterocycles with acetyl chloride. It is observed that all the complexes worked as efficient catalysts. The structural type of complexes was studied by an X-ray powder diffractogram (XRD). The mixed ligand complexes with PPh3 ligand show greater activity as compared to Phen complexes and Schiff base complexes. Especially complex [Ni(L)(PPh3)2Cl2] efficiently worked as a catalyst because of high thermal stability (TGA-DSC) and large catalytic surface area (BET).
Facile one-pot synthetic access to libraries of diversely substituted 3-aryl (Alkyl)-coumarins using ionic liquid (IL) or conventional base/solvent, and an IL-mediated approach to novel coumarin-bearing diaryl-ethynes
Kalkhambkar, Rajesh G.,Laali, Kenneth K.,Malunavar, Shruti S.,Prabhala, Pavankumar,Savanur, Hemantkumar M.,Sutar, Suraj M.
supporting information, (2020/04/08)
The in-situ formed carbonylimidazole derivatives of Ar(alkyl)-CH2COOH react at r.t. with substituted salicylaldehydes in [BMIM][PF6] or [BMIM][BF4] as solvent, and [PAIM][NTf2] as basic-IL, to produce libraries of 3-aryl(alkyl)coumarins. Whereas these reactions can also be performed with similar efficiency in THF by employing DBU, the IL approach offers easier work-up and recycling of the IL solvent. An IL-mediated approach to the synthesis of novel coumarin-bearing diaryl-ethynes by the Sonogshira reaction is also reported, and the potential for recycling/reuse of the IL solvent is shown.
Efficient CDI/CH3SO3H-catalyzed, microwave-assisted synthesis of 2-substituted benzothiazoles
Li, Yao-Wei,Zhang, Pei-Ming,Li, Rui,Bai, Yan,Yu, Yu,Gan, Zong-Jie
supporting information, p. 34 - 39 (2019/05/04)
CDI combined with CH3SO3H was found to be highly effective for the cyclization of 2-aminothiophenol derivatives with carboxylic acids under MW condition. Fourteen benzothiazole derivatives were synthesized in good yield and their structures were characterized by1H-NMR,13C-NMR, IR and mass spectrometry. This simple, rapid synthetic method is believed to provide a useful process for the synthesis of 2-substituted benzothiazole compounds.
Length-Selective Synthesis of Acylglycerol-Phosphates through Energy-Dissipative Cycling
Bonfio, Claudia,Caumes, Cécile,Duffy, Colm D.,Patel, Bhavesh H.,Percivalle, Claudia,Tsanakopoulou, Maria,Sutherland, John D.
supporting information, p. 3934 - 3939 (2019/03/08)
The main aim of origins of life research is to find a plausible sequence of transitions from prebiotic chemistry to nascent biology. In this context, understanding how and when phospholipid membranes appeared on early Earth is critical to elucidating the prebiotic pathways that led to the emergence of primitive cells. Here we show that exposing glycerol-2-phosphate to acylating agents leads to the formation of a library of acylglycerol-phosphates. Medium-chain acylglycerol-phosphates were found to self-assemble into vesicles stable across a wide range of conditions and capable of retaining mono- and oligonucleotides. Starting with a mixture of activated carboxylic acids of different lengths, iterative cycling of acylation and hydrolysis steps allowed for the selection of longer-chain acylglycerol-phosphates. Our results suggest that a selection pathway based on energy-dissipative cycling could have driven the selective synthesis of phospholipids on early Earth.
Imidazolium chloride: An efficient catalyst for transamidation of primary amines
Tian, Qingqiang,Gan, Zongjie,Wang, Xuetong,Li, Dan,Luo, Wen,Wang, Huajun,Dai, Zeshu,Yuan, Jianyong
supporting information, (2018/09/10)
A highly efficient and convenient protocol of imidazolium chloride (30 mol %) catalyzed amidation of amines with moderate to excellent yields was reported. The protocol shows broad substrate scope for aromatic, aliphatic, and heterocyclic primary amines.
POLYIMIDE PRECURSOR COMPOSITION AND PREPARATION METHOD AND USE THEREOF
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Page/Page column 22, (2016/10/09)
The present invention provides a polyimide precursor composition comprising a polyimide precursor and a thermal base generator having the structure of formula (1): wherein R1, R2, R3, R4, R5 and are as defined in the specification. The present invention also provides a polyimide prepared from the aforementioned precursor composition, and a preparation method thereof.
