IR-spektroskopische Untersuchungen an NH- und ND-Formazanen

1968 ◽  
Vol 23 (8) ◽  
pp. 1064-1071 ◽  
Author(s):  
W. Otting ◽  
F. A. Neugebauer
Keyword(s):  
Ir Spectra ◽  
Path Length ◽  
Hydrogen Bridge ◽  
Low Field

The solid and solution IR spectra of the yellow formazans (1) show in most cases a strong J'(NH) or ν (ND) band. The ν (NH) absorption of the red formazans (2) is so weak (ε ≈ 1 [liter mole-1 cm-1]), that it is only observed in solutions and with long path length. In the case of C-ethoxycarbonyl-N.N′-diphenylformazan opening of the intramolecular N — H - - - N hydrogen bridge by light gives rise to a new intramolecular N — H - - - O hydrogen bridge. The nuclear N — H resonance of the red formazans is shifted far to low field (14 p. p.m.).

scholarly journals Synthese und Eigenschaften unsymmetrischer Diketopiperazine des Cysteins / Synthesis and Properties of Unsymmetrical Diketopiperazines of Cysteine

1971 ◽  
Vol 26 (11) ◽  
pp. 1144-1151 ◽  
Author(s):  
V. Rossbach, ◽  
H. Wenck
Keyword(s):  
Ir Spectra ◽  
Functional Groups ◽  
Hydrogen Bridge ◽  
Subsequent Reduction ◽  
Oh Groups ◽  
Nucleophilic Reactivity ◽  
Kinetics Of

The synthesis of cyclo (c)-cys-ser, c-cys-asp and c-cys-try via cyclisation of the corresponding cystin-dipeptidesters and subsequent reduction of the disulfides of the diketopiperazines with mercapto-ethanole is described. The ir-spectra of the cyclo-dipeptides and their disulfides were studied with regard to interactions of the functional groups. The spectra indicate a strong hydrogen bridge between the OH-groups of c-cys-ser-disulfide and interactions between the SH and other functional groups of the above mentioned diketopiperazines. The kinetics of the reaction of cysdiketopiperazines with N-ethylmaleimide and p-nitro-phenylacetate were studied. The SH-groug of cys-diketopiperazines has a greater nucleophilic reactivity towards p-nitro-phenylacetate than was expected on the basis of the pKSH-values.

scholarly journals SYNTHESIS OF 3-(2-PYRIDYL)-N-METHYL-1,2,4-TRIAZOLE-5-ACETIC ACID ETHYL ESTER AND THEIR COORDINATION COMPOUNDS WITH Pd(II)

2017 ◽  
pp. 40-42
Author(s):  
Yu. Ogorodnik ◽  
D. Khomenko ◽  
R. Doroschuk ◽  
R. Lampeka
Keyword(s):  
Acetic Acid ◽  
Ir Spectra ◽  
Ethyl Ester ◽  
1H Nmr ◽  
Pyridine Ring ◽  
Acid Ethyl Ester ◽  
Ester Group ◽  
Weak Field ◽  
Low Field ◽  
Composition And Structure

Alkylation of 3-(2-pyridyl)-1,2,4-triazole-5-acetic acid with iodomethane leads to formation of 3-(2-pyridyl)-N1-methyl-1,2,4-triazole-5-acetic acid ethyl ester (L1) and 3-(2-pyridyl)-N2-1,2,4-triazole-5-acetic acid ethyl ester (L2). It was also managed to identify the compound ethyl ester 3-(2-pyridyl)-N2-methyl-1,2,4-triazol-5-yl-α-propionic acid (L3) which is the product of alkylation of L2 in the methylene group. L1-3 were used for synthesis of palladium(II) complexes PdL1Cl2, PdL2Cl2 and PdL3Cl2. The composition and structure of obtained compounds were proposed on the basis of IR and 1H NMR spectroscopy data and elemental analysis. IR spectra of synthesized ligands have a lot in common, due to their structure similarity. As a result of coordination all signals in the IR spectra are shifted besides bands of ester groups. 1H NMR spectra of obtained ligands is bit similar, this is due to their structure. Signals of pyridine ring protons 3-(2-pyridyl)-N1-methyl-1,2,4-trazole-5-acetic acid ethyl ester shifted to 0.11–0.13 ppm in a weak field in compare with izomers. N1–CH3 signals are shifted to lower field than N2–CH3, it can be explained by the influence of negative magnetic anisotropy of pyridine ring. Methyl and methylene signals of ester group are located nearly in the same field in L1–3. Coordination of all ligands occurs through the nitrogen atom of pyridine ring and N4-triazole. In this case all L1, L2 and L3 signals of pyridine protons suffer shift to a low field. Methyl and methylene signals of ester group almost no shifted what indicate that no coordination through oxygen atom.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

LOW FIELD E.S.R, IN THE SUPERCONDUCTING RELAXED STATE OF (TMTSF)2C104AT LOW TEMPERATURE

1983 ◽  
Vol 44 (C3) ◽  
pp. C3-1033-C3-1036 ◽  
Author(s):  
J. M. Delrieu ◽  
N. S. Sullivan ◽  
Bechgaard
Keyword(s):  
Low Temperature ◽  
Low Field
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