Synthesis, Characterization, and Tautomeric Properties of Some Azo-azomethine Compounds

2012 ◽  
Vol 67 (2) ◽  
pp. 159-164 ◽  
Author(s):  
Kourosh Hamidian ◽  
Mohsen Irandoust ◽  
Ezzat Rafiee ◽  
Mohammad Joshaghani
Keyword(s):  
Solid Phase ◽  
Bathochromic Shift ◽  
Aromatic Diamine ◽  
Absorption Bands ◽  
Aromatic Diamines ◽  
Azo Compound ◽  
Intramolecular Hydrogen ◽  
Azomethine Compounds ◽  
Strong Intramolecular Hydrogen Bond ◽  
Positive Solvatochromism

The primary azo compound 1-(3-formyl-4-hydroxyphenylazo)-4-nitrobenzene reacts with some aliphatic and aromatic diamines and yields the corresponding azo-azomethine compounds. These compounds were characterized by elemental analysis, IR, UV/Vis, and NMR spectroscopy. The primary azo compound exists entirely in the azo form in solution as well as in the solid phase. The tautomeric structure of azo-azomethine compounds heavily depends on the solvent and the substituents. Aliphatic diamine-based compounds favor the enol-imine tautomer while aromatic diamine-based compounds have structures that lie between the two enol-imine and keto-amine tautomers due to a relatively strong intramolecular hydrogen bond. The compounds exhibit positive solvatochromism (bathochromic shift) so that their absorption bands move toward longer wavelengths as the polarity of the solvents increases. In addition, UV/Vis spectrophotometry has shown that the studied compounds have molar extinction coefficients larger than 40000.

Cellulose organic solvents: V. Conformational aspects of N,N-dimethyl ethanolamine N-oxide in its crystalline and diluted states

1984 ◽  
Vol 62 (1) ◽  
pp. 6-10 ◽  
Author(s):  
E. R. Maia ◽  
A. Péguy ◽  
S. Pérez
Keyword(s):  
Tertiary Amine ◽  
Amine Oxide ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Cyclic Form ◽  
Asymmetric Unit ◽  
Ir And Nmr Spectroscopy ◽  
Conformational Investigation ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

N,N-Dimethyl ethanolamine N-oxide (DMEAO) belongs to the class of tertiary amine oxide molecules that are good solvents for cellulose, although not being cyclic. Crystallographic investigation shows that anhydrous DMEAO is monoclinic, space group Cc, a = 25.725(9), b = 7.023(4), c = 9.483(5) Å, β = 101.16(10)°, Z = 12. The crystal structure has been solved by direct methods and refined to a final R value of 0.063 for 575 observed reflexions. Three independent molecules are found within the asymmetric unit; one of these displays a pseudo-cyclic form dictated by the occurrence of a strong intramolecular hydrogen bond. Conformational investigation of DMEAO in solution, using ir and nmr spectroscopy shows that this pseudo-cyclic form is more likely to occur in diluted states. These findings are related to the ability of this tertiary amine oxide to act as a good solvent, up to a water content of one water molecule per DMEAO molecule.

(1′R,3S)-2-Oxo-1-(1′-phenylethyl)piperidine-3-carboxylic acid: a case of a very strong intramolecular hydrogen bond

2004 ◽  
Vol 60 (11) ◽  
pp. o2110-o2112
Author(s):  
Ana-María Lumbreras-García ◽  
Alberto Galindo-Guzmán ◽  
Dino Gnecco ◽  
Joel-Luis Terán ◽  
Sylvain Bernès
Keyword(s):  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Intramolecular Hydrogen Bond ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

scholarly journals SYNTHESIS AND SPECTRAL CHARACTERISTICS OF PERSPECTIVE NANOSIZED CARBON QUANTUM DOTS FOR ADSORPTION AND CATALYTIC PROCESSES

2020 ◽  
Vol 86 (1) ◽  
pp. 3-11
Author(s):  
Volodymyr Ogenko ◽  
Svitlana Orysyk ◽  
Ljudmila Kharkova ◽  
Oleg Yanko
Keyword(s):  
Quantum Dots ◽  
Bathochromic Shift ◽  
Spectral Characteristics ◽  
Carbon Quantum Dots ◽  
Hypsochromic Shift ◽  
Absorption Bands ◽  
Rhodium Chloride ◽  
Electron Transitions ◽  
Trivalent State ◽  
Adsorption Processes

Processes of interaction between carbon quantum dots (CQDs) and solutions of rhodium, ruthenium and palladium chlorides in the surface layer have been investigated by electron and IR spectroscopy. When rhodium chloride is added to a solution of CQDS, a bathochromic shift of the β- and p-absorption bands (ABs) at 48725 and 41711 cm-1 as well as hypsochromic shift of the α-AB at 28935 cm-1 indicate that rhodium adsorption occurs on the surface of CQDs. The bathochromic shift of the absorption bands at 22400 сm1 together with the hypsochromic shift of ABs corresponding to d-d electron transitions in the metal ions indicates the formation of rhodium with CQDs. When ruthenium and palladium chlorides are added to an aqueous solution of CQDs, the intensive of ABs characterizing the complex anions [RuCl6]3-, [RuCl6]2- or [PdCl4]2- are absent in the UV-Vis spectra. This indicates the passage of adsorption processes of metals on the surface of CQDs.  The present of ABs (at 27055 and 25125 сm-1) indicate the trivalent state of ruthenium ion; the p-ABs bathochromic shift as well as α-ABs hypsochromic shift indicates the probable complex formation of CQDs with Ru3+ ions. The change in the position of the absorption bands of d-d electron transitions (at 25448 сm1) together with the bathochromic shift of p-ABs and hypsochromic shift of α-ABs indicates a change in coordination environment in the palladium ion with the possible formation of Pd → N bond. The IR-spectra data of CQDs showed the presence of a number of characteristic ABs for functionalized CQDs: ν(N–H) at 3260 сm1, (C=O) at 1830, 1840 and 1850 сm1, –С=O(NH) at 1770 сm1, ν(C=N) at 1680 and δ(N–H) at 1640 сm1, which confirms the coordination of metals on the surface of CQDs.

Aromatic amides. IX. Temperature effects on the N.M.R. spectra of substituted acetanilides

1974 ◽  
Vol 27 (12) ◽  
pp. 2617 ◽  
Author(s):  
ID Rae
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Benzene Ring ◽  
Intramolecular Hydrogen Bond ◽  
Temperature Effects ◽  
Dimethyl Sulphoxide ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond ◽  
Ortho Substituent

N.m.r. spectra have been measured for several anilides in dimethyl sulphoxide solution for temperatures in the range 40-140�. The change of the N-H chemical shift with temperature depends on the nature of the ortho substituent on the benzene ring, being least when a strong intramolecular hydrogen bond is possible between the amide N-H and the ortho substituent. For 2?-nitroanilides, the 6?- proton becomes increasingly deshielded as the temperature is raised.

scholarly journals Six-fold C–H borylation of hexa-peri-hexabenzocoronene

2020 ◽  
Vol 16 ◽  
pp. 391-397 ◽  
Author(s):  
Mai Nagase ◽  
Kenta Kato ◽  
Akiko Yagi ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Density Functional ◽  
Bathochromic Shift ◽  
Density Functional Theory Calculations ◽  
Absorption Bands ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Polycyclic Aromatic ◽  
Direct Functionalization ◽  
Poorly Soluble

Hexa-peri-hexabenzocoronene (HBC) is known to be a poorly soluble polycyclic aromatic hydrocarbon for which direct functionalization methods have been very limited. Herein, the synthesis of hexaborylated HBC from unsubstituted HBC is described. Iridium-catalyzed six-fold C–H borylation of HBC was successfully achieved by screening solvents. The crystal structure of hexaborylated HBC was confirmed via X-ray crystallography. Optoelectronic properties of the thus-obtained hexaborylated HBC were analyzed with the support of density functional theory calculations. The spectra revealed a bathochromic shift of absorption bands compared with unsubstituted HBC under the effect of the σ-donation of boryl groups.

Structure–Property Relationships in Addition Polyimides. II. Resins from Three-Ring Aromatic Diamines Containing Carbonyl and Methylene Groups

1997 ◽  
Vol 9 (2) ◽  
pp. 161-176 ◽  
Author(s):  
Peter Delvigs ◽  
David L Klopotek ◽  
Paul J Cavano
Keyword(s):  
Interlaminar Shear Strength ◽  
Aromatic Diamine ◽  
Flexural Properties ◽  
Structure Property ◽  
Aromatic Diamines ◽  
Structure Property Relationships ◽  
Methylene Groups ◽  
Interlaminar Shear ◽  
Bridging Groups

The use of flexibilized three-ring aromatic diamine moieties was investigated in an effort to improve the processing characteristics of addition-type polyimide resins. A series of 10 diamines containing carbonyl and methylene bridging groups was synthesized. The diamines were polymerized with the dimethylester of 3,3′, 4,4′-benzophenonetetracarboxylic acid (BTDE), using the monomethyl ester of nadic acid (NE) as an endcap. The effect of diamine structure on the solubility and rheological properties during cure was determined. The effect of diamine structure and formulated molecular weight on the thermo-oxidative stability and glass transition temperature of the polyimides was also investigated. Unidirectional laminates were fabricated from selected resins, using carbon fibre as the reinforcement. Interlaminar shear strength and flexural properties of the laminates were determined. The results indicate that polyimides from some of the diamines containing methylene bridging groups have potential as matrix resins for long-term applications at temperatures up to 300 °C.

Experimental evidence for trapped exciton states in liquid rare gases

1970 ◽  
Vol 317 (1528) ◽  
pp. 113-131 ◽  
Keyword(s):  
Experimental Evidence ◽  
Absorption Spectra ◽  
Disordered Systems ◽  
Vacuum Ultraviolet ◽  
Solid Phase ◽  
Liquid System ◽  
Rare Gases ◽  
Line Broadening ◽  
Absorption Bands ◽  
Additional Line

In connexion with studies of the electronic structure of disordered systems, we enquire whether there exist exciton states in simple liquids. We report the results of a vacuum ultraviolet spectroscopic study of liquid argon and of liquid krypton doped with xenon. Experimental evidence was obtained for Wannier-Mott type impurity states in liquids which have no parentage in the excited states of the isolated atoms constituting the dense fluid. The absorption spectra of the doped liquid rare gases were monitored in the region 160 to 120 nm. The following experimental results are reported: (a) In the Xe/Ar liquid two absorption bands corresponding to the 1 S 0 → 3 P 1 and to the 1 S 0 → 1 P 1 transitions (or alternatively to the n = 1 Wannier states) were identified at 141 nm (8.80eV)† and at 123nm (10.1 eV). An additional line was observed at 127 nm (9.76eV). (b) In the Xe/Kr liquid three absorption bands were observed at 144.5 nm (8.59 eV), 125.5 nm (9.89 eV) and 129 nm (9.6 eV). (c) The absorption spectra of the doped liquids were compared with the spectra of 1 cm thick doped solid rare-gas crystals. From these results we conclude that: (a) The 127 nm (9.76 eV) band in the Xe/Ar liquid system and the 129 nm (9.61 eV) band in the Xe/Kr liquid system cannot be attributed to a perturbed ‘atomic’ state and are assigned to the n = 2 Wannier state in the liquid. (b) Line broadening of exciton states in the liquid can be accounted for by a simple scattering model. (c) Preliminary information on band gaps in liquid rare gases were obtained from the spectroscopic data. (d) The effect of liquid-solid phase transition on the line broadening of exciton states is consistent with electron mobility data in these systems.

The intramolecular hydrogen bond in some β-nitroalcohols. Chemistry of nitroalkanes. Part CXIX

1977 ◽  
Vol 55 (13) ◽  
pp. 2504-2509 ◽  
Author(s):  
E. Lipczyńska-Kochany ◽  
T. Urbański
Keyword(s):  
Hydrogen Bond ◽  
Experimental Evidence ◽  
Intramolecular Hydrogen Bond ◽  
Infrared Absorption ◽  
Nmr Spectra ◽  
Absorption Bands ◽  
Intramolecular Hydrogen ◽  
Infrared Absorption Bands

New experimental evidence is given on the existence of an intramolecular hydrogen bond in β-nitroalcohols between the nitro and hydroxylic groups. The conclusion is based on examination of na → π* and infrared absorption bands and nmr spectra.

Preparation and characterization of some new diaminobisimides

1994 ◽  
Vol 6 (4) ◽  
pp. 287-301 ◽  
Author(s):  
D G Hawthorne ◽  
J H Hodgkin ◽  
M B Jackson ◽  
J W Loder ◽  
T C Morton
Keyword(s):  
Gel Permeation Chromatography ◽  
Aromatic Diamine ◽  
Side Reactions ◽  
Amino Groups ◽  
Aromatic Diamines ◽  
Reaction Conditions ◽  
Condensation Polymers ◽  
Yield And Purity ◽  
C Nmr

A series of stable diaminobisimides (DABIs) has been prepared as alternatives to simple aromatic diamines for use in the preparation of condensation polymers. These DABIs were prepared by reacting two moles of an aromatic diamine with one mole of a dianhydride under conditions that minimize side reactions and the formation of oligomers. In many cases, the pure DABI consisting of two moles of the diamine and one mole of the dianhydride (i.e. the 2:1 product) can be obtained free of oligomers (i.e. the 3:2, 4:3 etc products). The studies have shown that the major factor determining the yield and purity of a DABI is the extent of conjugation between the two amino groups in the starting diamine: to a lesser extent steric effects in the diamines also influence the product composition. The reaction conditions necessary to produce these new DABIs are described together with extensive characterization of these materials by FTIR,1H and 13C NMR and gel permeation chromatography. The results indicate that pure DABIs are more manageable materials than the impure. insoluble materials previously described in the literature and can be used successfully to produce useful high-temperature stable polymers.

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