Factors Governing the Three-Dimensional Hydrogen-Bond Network Structure of Poly(m-Phenylene Isophthalamide) and a Series of Its Model Compounds (4):  Similarity in Local Conformation and Packing Structure between a Complicated Three-Arm Model Compound and the Linear Model Compounds

2006 ◽  
Vol 110 (42) ◽  
pp. 20858-20864 ◽  
Author(s):  
Piyarat Nimmanpipug ◽  
Kohji Tashiro ◽  
Orapin Rangsiman
Keyword(s):  
Hydrogen Bond ◽  
Linear Model ◽  
Network Structure ◽  
Model Compound ◽  
Three Dimensional ◽  
Hydrogen Bond Network ◽  
Model Compounds ◽  
Packing Structure ◽  
Local Conformation ◽  
Bond Network

(NH4)[B3PO6(OH)3]·0.5H2O

2007 ◽  
Vol 63 (11) ◽  
pp. i185-i185 ◽  
Author(s):  
Wei Liu ◽  
Jingtai Zhao
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Water Molecules ◽  
Hydrogen Bond Network ◽  
Ammonium Ions ◽  
One Dimensional ◽  
Bond Network ◽  
Solvothermal Conditions

The title compound, ammonium catena-[monoboro-monodihydrogendiborate-monohydrogenphosphate] hemihydrate, was obtained under solvothermal conditions using glycol as the solvent. The crystal structure is constructed of one-dimensional infinite borophosphate chains, which are interconnected by ammonium ions and water molecules via a complex hydrogen-bond network to form a three-dimensional structure. The water molecules of crystallization are disordered over inversion centres, and their H atoms were not located.

scholarly journals (Acetonitrile-κN)aqua[N,N′-bis(pyridin-2-ylmethyl)ethane-1,2-diamine-κ4N,N′,N′′,N′′′]zinc(II) perchlorate

2017 ◽  
Vol 73 (10) ◽  
pp. 1568-1571
Author(s):  
Ugochukwu Okeke ◽  
Yilma Gultneh ◽  
Ray J. Butcher
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Three Dimensional ◽  
Structural Features ◽  
Hydrogen Bond Network ◽  
Asymmetric Unit ◽  
Bond Network ◽  
Bifurcated Hydrogen Bond ◽  
Coordinated Water ◽  
Ionic Hydrogen Bonding

The structure of the title compound, [Zn(C14H18N4)(C2H3N)(H2O)](ClO4)2, contains a six-coordinate cation consisting of the tetradentate bispicen ligand, coordinated water, and coordinated acetonitrile, with the latter two ligands adopting acisconfiguration. There are two formula units in the asymmetric unit. Both cations show almost identical structural features with the bispicen ligand adopting the more commoncis-β conformation. One of the four perchlorate anions is disordered over two positions, with occupancies of 0.9090 (15) and 0.0910 (15). There is extensive inter-ionic hydrogen bonding between the perchlorate anions and O—H and N—H groups in the cations, including a bifurcated hydrogen bond between an N—H group and two O atoms of one perchlorate anion. As a result of this extended hydrogen-bond network, the ions are linked into a complex three-dimensional array.

scholarly journals Reorientation-induced relaxation of free OH at the air/water interface revealed by ultrafast heterodyne-detected nonlinear spectroscopy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ken-ichi Inoue ◽  
Mohammed Ahmed ◽  
Satoshi Nihonyanagi ◽  
Tahei Tahara
Keyword(s):  
Hydrogen Bond ◽  
Vibrational Relaxation ◽  
Three Dimensional ◽  
Technical Difficulty ◽  
Nonlinear Spectroscopy ◽  
Water Interface ◽  
Hydrogen Bond Network ◽  
Relaxation Dynamics ◽  
Air Water Interface ◽  
Bond Network

Abstract The uniqueness of water originates from its three-dimensional hydrogen-bond network, but this hydrogen-bond network is suddenly truncated at the interface and non-hydrogen-bonded OH (free OH) appears. Although this free OH is the most characteristic feature of interfacial water, the molecular-level understanding of its dynamic property is still limited due to the technical difficulty. We study ultrafast vibrational relaxation dynamics of the free OH at the air/water interface using time-resolved heterodyne-detected vibrational sum frequency generation (TR-HD-VSFG) spectroscopy. With the use of singular value decomposition (SVD) analysis, the vibrational relaxation (T1) times of the free OH at the neat H2O and isotopically-diluted water interfaces are determined to be 0.87 ± 0.06 ps (neat H2O), 0.84 ± 0.09 ps (H2O/HOD/D2O = 1/2/1), and 0.88 ± 0.16 ps (H2O/HOD/D2O = 1/8/16). The absence of the isotope effect on the T1 time indicates that the main mechanism of the vibrational relaxation of the free OH is reorientation of the topmost water molecules. The determined sub-picosecond T1 time also suggests that the free OH reorients diffusively without the switching of the hydrogen-bond partner by the topmost water molecule.

A hydrogen-bond network at the active site of subtilisin BPN'

1970 ◽  
Vol 257 (813) ◽  
pp. 119-124 ◽  
Keyword(s):  
Hydrogen Bond ◽  
Active Site ◽  
Serine Proteases ◽  
Catalytic Mechanism ◽  
Three Dimensional ◽  
Hydrogen Bond Network ◽  
The Common ◽  
Bond Network ◽  
The One ◽  
Active Site Region

Further examination of the active site region in our X-ray crystallographic model of subtilisin BPN' reveals a hydrogen-bond network that bears a remarkable resemblance to the one found in a- chymotrypsin. It involves the side chains of the reactive Ser-221, His-64, Asp-32 and Ser-33. Otherwise the two enzymes have entirely different three-dimensional structures. This observation suggests that the common hydrogen bond network plays some essential role in the catalytic mechanism of serine proteases generally.

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