Study of the protonation of simple Schiff bases in solvents of various polarity by means of Raman spectroscopy

1991 ◽  
Vol 69 (2) ◽  
pp. 239-245 ◽  
Author(s):  
S. Alex ◽  
P. Turcotte ◽  
R. Fournier ◽  
D. Vocelle
Keyword(s):  
Amino Acids ◽  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Schiff Base ◽  
Organic Acids ◽  
Schiff Bases ◽  
Spectral Response ◽  
The Other ◽  
Intensity Measurements ◽  
Bonding Properties

In this study, the protonation of simple Schiff bases by organic acids in various solvents is investigated by Raman spectroscopy and the spectral response of the C=N+ stretching mode is correlated with the macroscopic properties of the medium surrounding the imine. Upon protonation, the unperturbed C=N stretch increases in frequency due to the combination of the coupling with the C=N+H bend and a partial rehybridization of the C=N bond. Depending on the proton location relative to that of its counterion, one mechanism may prevail over the other. Intensity measurements show that protonation is mostly controlled by the hydrogen bonding properties of the solvent and by the polarity of the medium. However, whatever the solvent, full proton transfer cannot be achieved with organic acids with pKa similar to the COOH of amino acids found in visual or bacterial pigments, meaning that the protonation mechanism may depend upon particular properties of the protein. Key words: imines, protonation, Raman spectroscopy, rhodopsin, Schiff base.

scholarly journals Synthesis, Spectroscopic, Molecular Structure, and Antibacterial Studies of Dibutyltin(IV) Schiff Base Complexes Derived from Phenylalanine, Isoleucine, and Glycine

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Har Lal Singh ◽  
Jangbhadur Singh
Keyword(s):  
Amino Acids ◽  
Schiff Base ◽  
Schiff Bases ◽  
Molar Conductance ◽  
Schiff Base Complexes ◽  
Spectral Studies ◽  
E Coli ◽  
Elemental Analyses ◽  
In Vitro Antibacterial Activity

New series of organotin(IV) complexes and Schiff bases derived from amino acids have been designed and synthesized from condensation of1H-indole-2,3-dione, 5-chloro-1H-indole-2,3-dione, andα-amino acids (phenylalanine, isoleucine, and glycine). All compounds are characterized by elemental analyses, molar conductance measurements, and molecular weight determinations. Bonding of these complexes is discussed in terms of their UV-visible, infrared, and nuclear magnetic resonance (1H,13C, and119Sn NMR) spectral studies. The results suggest that Schiff bases behave as monobasic bidentate ligands and coordinate with dibutyltin(IV) in octahedral geometry according to the general formula [Bu2Sn(L)2]. Elemental analyses and NMR spectral data of the ligands with their dibutyltin(IV) complexes agree with their proposed distorted octahedral structures. Few representative compounds are tested for their in vitro antibacterial activity against Gram-positive (B. cereus,Staphylococcusspp.) and Gram-negative (E. coli,Klebsiellaspp.) bacteria. The results show that the dibutyltin complexes are more reactive with respect to their corresponding Schiff base ligands.

Conformation and Hydrogen Bonding Properties of an Aziridinyl Peptide:  X-ray Structure Analysis, Raman Spectroscopy and Theoretical Investigations

2004 ◽  
Vol 108 (51) ◽  
pp. 11398-11408 ◽  
Author(s):  
Tanja Schirmeister ◽  
Alexander Breuning ◽  
Alexander Murso ◽  
Dietmar Stalke ◽  
Milena Mladenovic ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Structure Analysis ◽  
X Ray ◽  
Theoretical Investigations ◽  
Bonding Properties

High Pressure Raman Study of the Hydrolysis Reaction of Tmos and Teos

1990 ◽  
Vol 180 ◽  
Author(s):  
G. Hoang ◽  
J. Watson ◽  
T. W. Zerda
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Constant ◽  
High Pressure ◽  
Hydrogen Bonding ◽  
Raman Band ◽  
Dipole Moments ◽  
Hydrolysis Reaction ◽  
Or Groups ◽  
Bonding Properties ◽  
Raman Study

ABSTRACTHigh pressure Raman spectroscopy is used to monitor the hydrolysis reaction of TMOS in solutions with methanol, acetonitrile, acetone, dioxane and formamide, and of TEOS as a function of pH and the catalyst used. The rate constants for various solvents, temperatures and pressures are experimentally determined from the time dependence of Raman band intensities. It is shown that the reaction is slow in dioxane and fast in methanol or formamide. The volume of activation is found from the pressure dependence of the rate constant. The volume of activation, the dielectric constant, dipole moments and hydrogen bonding properties and their role in the hydrolysis reaction are discussed. It is shown that solvents which can form hydrogen bonding with Si-OR groups can increase the rate of the reaction.

Metallkomplexe mit biologisch wichtigen Liganden, CXXXVII [1]. Halbsandwich-Komplexe mit N, O-Chelaten und Schiff-Basen von β-Aminosäuren/ Metal Complexes of Biologically Important Ligands, CXXXVII [1]. Halfsandwich Complexes with N, O-Chelates and Schiff Bases of β-Amino Acids

2001 ◽  
Vol 56 (4-5) ◽  
pp. 403-410 ◽  
Author(s):  
Daniela Koch ◽  
Winfried Hoffmüller ◽  
Kurt Polborn ◽  
Wolfgang Beck
Keyword(s):  
Amino Acids ◽  
Schiff Base ◽  
Metal Complexes ◽  
Ethyl Ester ◽  
Schiff Bases ◽  
Schiff Base Ligand ◽  
Schiff Base Complexes ◽  
Single Isomer ◽  
Bidentate Schiff Base Ligand

Abstract β-Phenylalanine forms with chloro bridged complexes the chiral N, O-chelates Cp*Ir(Cl)(NH2CH(Ph)CH2CO2) and (p-cymene)Ru(Cl)(NH2CHPhCH2CO2) as mixture of two diastereoisomers. Similarly the palladium(III) and platinum(II) complexes (Et3P)(Cl)M(NH2CH(Ph)CH2CO2) (M = Pd, Pt) were obtained. Schiff base complexes (arene)(Cl)M(O2CC(R)=N-CH(R)CH(R)CH2CO2CH3) (arene = Cp*, p-cymene; M = Ir, Ru) were synthesized from the chloro-bridged compounds, 2-oxocarboxylates and β-alanine or β-phenylalanine methylester. The Cp*Ir complex with a tridendate dianionic Schiff base generated from pyruvate and β-phenylalaninate is obtained as a single isomer. Cp*Ir(Cl) forms a complex with an N, O-bidentate Schiff base ligand from glycinate and acetylacetic ethyl ester.

scholarly journals Crystal structure of a 2:1 piroxicam–gentisic acid co-crystal featuring neutral and zwitterionic piroxicam molecules

2016 ◽  
Vol 72 (12) ◽  
pp. 1714-1717
Author(s):  
Elizabeth M. Horstman ◽  
Jeffery A. Bertke ◽  
Toby J. Woods ◽  
Paul J. A. Kenis
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
The Other ◽  
Acid Molecule ◽  
Dihydroxybenzoic Acid ◽  
Neutral Form ◽  
Gentisic Acid ◽  
Whole Molecule Disorder

A new 2:1 co-crystal of piroxicam and gentisic acid [systematic name: 4-hydroxy-1,1-dioxo-N-(pyridin-2-yl)-2H-1λ6,2-benzothiazine-3-carboxamide–2-(4-oxido-1,1-dioxo-2H-1λ6,2-benzothiazine-3-amido)pyridin-1-ium–2,5-dihydroxybenzoic acid, 2C15H13N3O4S·C7H6O4] has been synthesized using a microfluidic platform and initially identified using Raman spectroscopy. In the co-crystal, one piroxicam molecule is in its neutral form and an intramolecular O—H...O hydrogen bond is observed. The other piroxicam molecule is zwitterionic (proton transfer from the OH group to the pyridine N atom) and two intramolecular N—H...O hydrogen bonds occur. The gentisic acid molecule shows whole-molecule disorder over two sets of sites in a 0.809 (2):0.191 (2) ratio. In the crystal, extensive hydrogen bonding between the components forms layers propagating in theabplane.

scholarly journals New 1,2,3-Triazole Scaffold Schiff Bases as Potential Anti-COVID-19: Design, Synthesis, DFT-Molecular Docking, and Cytotoxicity Aspects

Vaccines ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1012
Author(s):  
Musa A. Said ◽  
Daoud J. O. Khan ◽  
Fawzia F. Al-blewi ◽  
Nadia S. Al-Kaff ◽  
Adeeb A. Ali ◽  
...  
Keyword(s):  
Schiff Base ◽  
Schiff Bases ◽  
Quantitative Structure Activity Relationship ◽  
Structure Activity Relationship ◽  
The Other ◽  
Activity Relationship ◽  
Energy Structure ◽  
Quantitative Structure ◽  
Schiff Base Ligands ◽  
Structure Activity

Schiff bases encompassing a 1,2,3-triazole motif were synthesized using an efficient multi-step synthesis. The formations of targeted Schiff base ligands were confirmed by different spectroscopic techniques (FT-IR, 1H NMR, 13C NMR, and CHN analysis). The spectral data analysis revealed that the newly designed hydrazones exist as a mixture of trans-E and cis-E diastereomers. Densityfunctional theory calculations (DFT) for the Schiff bases showed that the trans-trans form has the lowest energy structure with maximum stability compared to the other possible geometrical isomers that could be present due to the orientation of the amidic NH–C=O group. The energy differences between the trans-trans on one side and syn-syn and syn-trans isomers on the other side were 9.26 and 5.56 kcal/mol, respectively. A quantitative structure-activity relationship investigation was also performed in terms of density functional theory. The binding affinities of the newly synthesized bases are, maybe, attributed to the presence of hydrogen bonds together with many hydrophobic interactions between the ligands and the active amino acid residue of the receptor. The superposition of the inhibitor N3 and an example ligand into the binding pocket of 7BQY is also presented. Further interesting comparative docking analyses were performed. Quantitative structure-activity relationship calculations are presented, illustrating possible inhibitory activity. Further computer-aided cytotoxicity analysis by Drug2Way and PASS online software was carried out for Schiff base ligands against various cancer cell lines. Overall, the results of this study suggest that these Schiff base derivatives may be considered for further investigation as possible therapeutic agents for COVID-19.

scholarly journals Schiff bases of 1,5-diarylpent-4-ene-1,3-diones and their metal complexes: Synthesis, characterization and fluorescent studies

2020 ◽  
pp. 62-62
Author(s):  
Muhammed Ummathur ◽  
Radhika Pallikkavil ◽  
Krishnannair Krishnankutty
Keyword(s):  
Hydrogen Bonding ◽  
Schiff Base ◽  
Metal Complexes ◽  
Spectral Data ◽  
Schiff Bases ◽  
1H Nmr ◽  
Fluorescence Intensity ◽  
Metal Ion ◽  
Fluorescence Emission ◽  
Fluorescent Studies

Four Schiff bases (H2L1 to H2L4) have been synthesized by the con-densation between o-aminophenol and unsaturated diketones (1,5-diarylpent-4--ene-1,3-diones). Analytical, IR, 1H NMR and mass spectsral data revealed their existence in the imine-enamine form. Dibasic tetradentate coordination of the Schiff bases in their ML complexes [M = Cu(II), Ni(II), Co(II), Zn(II), Cd(II), and Hg(II)] has been established on the basis of physical, analytical and spectral data. The fluorescent studies of H2L4 show that fluorescence emission maxima shift with increase in polarity and hydrogen bonding ability of the solvent. Paramagnetic Cu(II), Ni(II) and Co(II) ions decrease the fluorescence intensity with increase in concentration of the metal ion while diamagnetic Zn(II), Cd(II) and Hg(II) ions have very little influence on the intensity of fluorescence of the Schiff base H2L4.

scholarly journals Review Article on Metal Complexes derived from 2’-hydroxyacetophenone based Schiff Base

2021 ◽  
Vol 37 (1) ◽  
pp. 25-32
Author(s):  
Pallavee Gupta ◽  
Dhananjay Dwivedi ◽  
Vijay R. Chourey
Keyword(s):  
Amino Acids ◽  
Schiff Base ◽  
Metal Complexes ◽  
Schiff Bases ◽  
Review Article ◽  
Amine Group ◽  
Oxidation Reduction ◽  
Schiff Base Formation ◽  
Base Formation

In this review article, we try to cover various studies have been done on 2’-hydroxyacetophenone based schiff bases and formed metal complexes such as Formation with diamine, amino acids etc., antibacterial, antifungal, cytotoxicity, larvicidal, oxidation-reduction and schiff base Formation with different amine group containing compounds etc.

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