Effects of pressure on the infrared spectra of some heterocyclic organosilicon and organogermanium compounds

1984 ◽  
Vol 37 (1) ◽  
pp. 23 ◽  
Author(s):  
SD Hamann ◽  
P Mazerolles ◽  
A Faucher ◽  
G Manuel
Keyword(s):  
Phase Transitions ◽  
Conformational Changes ◽  
Infrared Spectra ◽  
Functional Group ◽  
Organogermanium Compounds ◽  
Transannular Interaction

Measurements have been made of the infrared spectra of eight solid heterocyclic organosilicon and organogermanium compounds at pressures up to 5 GPa at normal temperature. Evidence is found of reversible conformational changes under pressure, and of phase transitions in some of the compounds. Unexpectedly, it appears that compression does not favour the transannular interaction that exists, in some cases, between the heteroatom (silicon or germanium) and a functional group on the opposite side of the ring.

Infrared spectra of N-acetyl-L-α-amino-acid N'-methylamides with aliphatic side chains in non-polar solvents

1981 ◽  
Vol 46 (3) ◽  
pp. 772-780 ◽  
Author(s):  
Jorga Smolíková ◽  
Jan Pospíšek ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Conformational Changes ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Side Chains ◽  
Polar Solvents

Infrared spectra of the L-alanine (I), L-leucine (II), L-valine (III) and L-tert-leucine (IV) N-acetyl N'-methylamides were measured. Amides I-IV are not self associated in tetrachlormethane in the concentration 2 . 10-5 mol l-1 at room temperature and in tetrachloroethylene in the concentration 1.5 . 10-4 mol l-1 at temperatures above 65° C. True conformational changes are observable only with the least flexible amide IV which exists at room temperature in a C5 conformation. This conformational type is also highly populated in the valine derivative III, but is less important in the alanine and leucine derivatives I and II in which the intramolecularly bonded C7 and the distorted hydrogen-nonbonded conformations contribute seriously.

scholarly journals Investigation of phase transitions in liquid crystal 12BBAA using window clustering of infrared spectra

2021 ◽  
Vol 341 ◽  
pp. 117233
Author(s):  
Natalia Osiecka-Drewniak ◽  
Mirosław A. Czarnecki ◽  
Zbigniew Galewski
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Infrared Spectra

Study of Reactive Precipitation in Vortex Impinging Streams Reactor

2012 ◽  
Vol 455-456 ◽  
pp. 617-623
Author(s):  
You Feng Li ◽  
Hong Qi Ye ◽  
Xian Da He ◽  
Hui Liu
Keyword(s):  
Specific Surface ◽  
Infrared Spectra ◽  
Barium Sulfate ◽  
Functional Group ◽  
Stirred Tank ◽  
Complexing Agent ◽  
Tetraacetic Acid ◽  
Orthorhombic Structure ◽  
Tank Reactor ◽  
Ellipsoidal Particles

The vortex impinging streams technology (VIS) has good micromixing in the precipitation processes. The experiments were loaded with two reactants, BaCl2and Na2SO4, using ethylene diamine tetraacetic acid (EDTA) as complexing agent, to prepare BaSO4 in the vortex impinging streams reactor at Re=2500, comparing with those in the stirred tank reactor (STR). The products were characterized by XRD, TEM, BET and FTIR. The results indicate barium sulfate superfine particles are crystallized in the orthorhombic structure with lattice parameters a=7.156 Å, b=8.881 Å, and c=5.454 Å. The size of the ellipsoidal particles from VIS is about 386 nm, with narrower distribution and finer dispersity than that from STR. The specific surface area of the particles from VIS is 29.25 m2/g, comparing to 11.95 m2/g from STR. The infrared spectra decades the surface of the prepared BaSO4absorbs the functional group of EDTA.

scholarly journals Phase Transitions and Conformational Changes in Monolayers of Human Apolipoproteins CI and AII

2003 ◽  
Vol 107 (46) ◽  
pp. 12897-12897
Author(s):  
Jaime Ruiz-García ◽  
Abel Moreno ◽  
Gerald Brezesinski ◽  
Helmuth Möhwald ◽  
Jaime Mas-Oliva ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Conformational Changes

Effect of functional group conformation on the infrared spectra of some gem difunctional phenylethylene derivatives

1969 ◽  
Vol 47 (17) ◽  
pp. 3147-3152 ◽  
Author(s):  
D. J. Currie ◽  
C. E. Lough ◽  
F. K. McClusky ◽  
H. L. Holmes
Keyword(s):  
Absorption Band ◽  
Functional Groups ◽  
Infrared Spectra ◽  
Functional Group ◽  
Plane Deformation ◽  
Carbonyl Groups ◽  
Deformation Bands ◽  
Or Groups ◽  
Out Of Plane ◽  
Stretching Vibrations

Except for the benzalmalononitriles, two functional group stretching vibrations occur in the infrared (i.r.) spectra of the β,β-difunctional-styrenes with similar functional groups. For geometrically homogeneous compounds with dissimilar functional groups only one absorption band occurs for each functional group. The two bands for similar functional groups have been ascribed to S-cis- and S-trans-conformations of the carbonyl groups with respect to the ethylene and variation in the frequencies of each of these oriented carbonyls to rotation of the functional group or groups out of the plane of the ethylene by steric factors.Frequencies for ethylenic C—H out of plane deformation bands for β-monofunctional styrenes accorded with those already assigned to this vibration. A similar assignment could not be made for the difunctional analogues.

Development of solid-state emissive o-carboranes and theoretical investigation of the mechanism of the aggregation-induced emission behaviors of organoboron “element-blocks”

2017 ◽  
Vol 196 ◽  
pp. 31-42 ◽  
Author(s):  
Kazuo Tanaka ◽  
Kenta Nishino ◽  
Shunichiro Ito ◽  
Honami Yamane ◽  
Kazumasa Suenaga ◽  
...  
Keyword(s):  
Excited State ◽  
Conformational Changes ◽  
Functional Group ◽  
Theoretical Calculations ◽  
Luminescent Properties ◽  
Ring Structure ◽  
Aggregation Induced Emission ◽  
Intramolecular Mobility ◽  
Fused Ring ◽  
Potential Strategy

This paper presents the aggregation-induced emission (AIE) properties of o-carborane derivatives and proposes a potential strategy for constructing AIE-active organoboron complexes via the enhancement of freedom of intramolecular mobility. Initially, the optical properties of o-carborane derivatives with or without the fused ring structure at the C–C bond in o-carborane in which elongation should be induced by photo-excitation according to theoretical calculations were compared. Accordingly, it was shown that large mobility at the C–C bond in o-carborane should be responsible for the annihilation of emission in solution, leading to the AIE property. From this result, it was presumed that by enhancing the freedom of intramolecular mobility in conventional luminescent organoboron complexes, the deactivation of the excited state in solution and emission recovery in the aggregate can be induced. Based on this idea, we have performed several studies and introduce two representative results. Firstly, the decrease in luminescent properties of boron dipyrromethene (BODIPY) in solution by introducing a movable functional group is explained. Next, the AIE behaviors of boron ketoiminates and the potential mechanism concerning conformational changes for the deactivation of the excited state in the solution state are illustrated. It is proposed that enhancement of the freedom of mobility in the excited state of luminescent organoboron complexes could be a potential strategy for realizing AIE behaviors.

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