Promoting helicity in carbohydrate-containing foldamers through long-range hydrogen bonds

2007 ◽  
pp. 831-833 ◽  
Author(s):  
David Rodríguez-Lucena ◽  
Juan M. Benito ◽  
Carmen Ortiz Mellet ◽  
José M. García Fernández
Keyword(s):  
Hydrogen Bonds ◽  
Long Range

scholarly journals An Uneven Chain-like Ferromagnetic Copper(II) Coordination Polymer Displaying Metamagnetic Behavior and Long-Range Magnetic Ordering

2021 ◽  
Vol 8 (1) ◽  
pp. 2
Author(s):  
Cai-Ming Liu ◽  
You Song
Keyword(s):  
Molecular Structure ◽  
Coordination Polymer ◽  
Hydrogen Bonds ◽  
Long Range ◽  
Three Dimensional ◽  
Magnetic Ordering ◽  
Antiferromagnetic Interaction ◽  
Ferromagnetic Coupling ◽  
One Dimensional ◽  
1D Chain

Ferromagnetic coupling exists in an uneven chain-like copper(II) complex with both end-on azido and syn-syn carboxylato bridges, (Cu3(L)2(N3)4(H2O)3)n (1, HL = 6-hydroxynicotinic acid). It is the first example of one-dimensional (1D) chain-like copper(II) coordination polymer showing both metamagnetic behavior and long-range magnetic ordering (Tc = 6.7 K), thanks to the interchain hydrogen bonds, which make a three-dimensional (3D) supramolecular array of the entire molecular structure and mediate the interchain antiferromagnetic interaction.

Photoluminescence Changes Induced by Self-Organisation in Bridged Silsesquioxanes

2006 ◽  
Vol 514-516 ◽  
pp. 118-122 ◽  
Author(s):  
Luís D. Carlos ◽  
Rute A. Sá Ferreira ◽  
Sonia S. Nobre ◽  
Michel Wong Chi Man ◽  
Joël J. E. Moreau ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Long Range ◽  
Local Structure ◽  
The Self ◽  
Time Resolved ◽  
Emission Properties ◽  
Self Assembling ◽  
Molecular Precursor ◽  
Long Range Ordering ◽  
Bridged Silsesquioxanes

Two organo-bridged silsequioxanes derived from the same molecular precursor were synthesized with completely different local structure, namely long-range ordering. The photoluminescence features (emission, excitation, and time-resolved modes) were studied in the temperature range 13-300 K and compared with those of the molecular precursor. The effects of the self-assembling of the nanobuild blocks on these emission properties were discussed in terms of the magnitude of the hydrogen bonds between adjacent organic groups.

Large perturbations of long-range nJ(1H,1H) and nJ(1H,19F) by the intramolecular hydrogen bonds in 2-mercaptobenzaldehyde, salicylaldehyde, and some derivatives. Reference structures for intramolecular hydrogen bonds

1993 ◽  
Vol 71 (7) ◽  
pp. 960-967 ◽  
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian ◽  
David M. McKinnon ◽  
Perry W. Spevack ◽  
Kerry J. Cox ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Long Range ◽  
Bond Formation ◽  
Coupling Constants ◽  
Hydrogen Bond Formation ◽  
Intramolecular Hydrogen Bonds ◽  
Large Perturbation ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

Precise 1H nuclear magnetic resonance spectral parameters are reported for salicyladehyde and its 3-fluoro and 5-fluoro derivatives in nonpolar solutions. Such data are also given for the 2-mercapto, 2-methylthio, and 2-methoxy derivatives of benzaldehyde. Comparison of the long-range coupling constants in the various compounds and their conformers shows a large perturbation of their magnitudes by hydrogen bond formation. For the salicylaldehyde system, the perturbation is particularly large for couplings involving the aldehyde proton and protons or fluorine nuclei placed ortho to the hydroxyl group. For example, 5Jt (F, CHO) is reduced by about 50%. The perturbation, as expected, is much smaller for coupling constants of nuclei remote from the site of the hydrogen bond. In 2-mercaptobenzaldehyde the long-range coupling constants are also sensitive to hydrogen bond formation, those involving the sulfhydryl proton markedly so compared to the hydroxyl proton in salicylaldehyde. The strength of the [Formula: see text] bond is discussed. It is argued that the reference conformer for the mercapto compound in such a discussion is less easily defined than for salicylaldehyde because [Formula: see text] are similar to [Formula: see text] energies. The experimental data for the CCl4 solutions imply a free energy of formation of the [Formula: see text] bond of 4.8(5) kJ/mol at 300 K. Molecular orbital computations on the four planar conformers of each salicylaldehyde and 2-mercaptobenzaldehyde with the 6-31 G**(5D) basis are reported. For salicylaldehyde, the [Formula: see text] arrangement is taken as the reference conformer, with a computed energy of 25.7 kJ/mol relative to the hydrogen-bonded structure. For 2-mercaptobenzaldehyde, the [Formula: see text] and [Formula: see text] conformers are calculated to be isoenergetic, at 5.1 kJ/mol relative to the hydrogen-bonded conformer. Hence either arrangement serves as a reference structure in computations of the strength of the hydrogen bond. The computations are consistent with the experimental results for solutions of the molecules under discussion. An appendix gives the computed geometries of the eight planar conformers, as well as some atomic charges, allowing a rationalization of the relative energies of the conformers.

Weakened Hydrogen Bonds in Water Confined between Lipid Bilayers: The Existence of a Long-Range Attractive Hydration Force

ChemPhysChem ◽  
2009 ◽  
Vol 10 (9-10) ◽  
pp. 1438-1441 ◽  
Author(s):  
Zoran Arsov ◽  
Michael Rappolt ◽  
Joze Grdadolnik
Keyword(s):  
Hydrogen Bonds ◽  
Lipid Bilayers ◽  
Long Range ◽  
Hydration Force

scholarly journals The long-range effect induced by untying hydrogen bonds for single cell test using SECM

2016 ◽  
Vol 207 ◽  
pp. 135-142 ◽  
Author(s):  
Qing Zheng ◽  
Yifan Yang ◽  
Yuanyuan Yan ◽  
Yu Yu ◽  
Yao Liu ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Single Cell ◽  
Long Range ◽  
Range Effect ◽  
Cell Test

Hydrogen Bonds of Water and CO Groups Coordinate Long-Range Structural Changes in the L Photointermediate of Bacteriorhodopsin†

Biochemistry ◽  
1996 ◽  
Vol 35 (13) ◽  
pp. 4063-4068 ◽  
Author(s):  
Yoichi Yamazaki ◽  
Satoru Tuzi ◽  
Hazime Saitô ◽  
Hideki Kandori ◽  
Richard Needleman ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Long Range ◽  
Structural Changes
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