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Hydrogen bond
About: Hydrogen bond is a research topic. Over the lifetime, 57701 publications have been published within this topic receiving 1306326 citations.
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TL;DR: In this article, the thermal behavior of PNIPAM in its concentrated D2O solution (20 wt %) was studied by FTIR and 2D-IR correlation spectroscopy.
Abstract: The thermal behavior of PNIPAM in its concentrated D2O solution (20 wt %) was studied by FTIR and 2D-IR correlation spectroscopy. The spectral data of the C−H groups and the Amide I region provide details about the changes of the hydrophobic and hydrophilic parts in the polymer respectively during a heating−cooling cycle. The reversal of peak positions of the C−H bands upon cooling indicates the reversibility of temperature-induced dehydration of the hydrophobic groups. The change in hydrogen bonding of CO···D−N constructed between dehydrated CO and N−D groups, as derived from the Amide I region, does not revert precisely in the cooling process due to the newly formed hydrogen bonds in the collapsed state, and a hysteresis phenomenon is observed. In our concentrated solution (20 wt %), the strength of those intra- and interchain hydrogen bonds even prevent the polymers from dissociating completely below the LCST during the cooling process. The microdynamics phase separation mechanism was obtained by appli...
273 citations
TL;DR: 3 subset 4Me(2)CO shows amorphous (nonporous)-to-crystal (porous) structural rearrangement in the Me( 2)CO adsorption and desorption process, where the framework of the 2-D motif is maintained.
Abstract: Flexible porous coordination polymers containing amide groups as a function origin have been synthesized and categorized as “Coordination Polymer with Amide Groups”. Bispyridyl ligands with a spacer of amide group afford two-dimensional (2-D) motifs with a deformed square grid, resulting in three-dimensional (3-D) frameworks of [Co(NO3)2(3-pna)2]n (1), [Co(Br)2(3-pna)2]n (2), and {[Co(NCS)2(4-peia)2]·4Me2CO}n (3 ⊃ 4Me2CO) (3-pna = N-3-pyridylnicotinamide, 4-peia = N-(2-pyridin-4-yl-ethyl)-isonicotinamide), where the 2-D motifs are bound by complementary hydrogen bond between the amide groups. In the case of the 3 ⊃ 4Me2CO, the amide groups form a contrivance for a dynamic porous framework because of their relevant position and orientation in the mutual nearest neighboring motifs. Consequently, 3 ⊃ 4Me2CO shows amorphous (nonporous)-to-crystal (porous) structural rearrangement in the Me2CO adsorption and desorption process, where the framework of the 2-D motif is maintained. The adsorption isotherm has thr...
273 citations
TL;DR: In this article, the Fourier transform infra-red (FT i.r.) spectra of regioselectively substituted methylcelluloses were used to model components of amorphous cellulose.
273 citations
TL;DR: The crystal structure of flavocytochrome b2 has been solved at 3.0 A resolution by the method of multiple isomorphous replacement with anomalous scattering by using a combination of maps both averaged and not averaged about the molecular symmetry axis.
273 citations
TL;DR: A new structure reported here of the bovine mitochondrial bc1 complex at 2.28 A resolution allows for the first time to reliably describe the binding of antimycin and shows that the intramolecular hydrogen bond described in solution and in the small-molecule structure is replaced by one involving the NH rather than carbonyl O of the amide linkage.
273 citations