scholarly journals Aptamer-Based Diagnostics and Therapeutics

2019 ◽  
Vol 12 (1) ◽  
pp. 6 ◽  
Author(s):  
Sarah Shigdar
Keyword(s):  
Hydrogen Bonding ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Base Pairing ◽  
Research Papers ◽  
Rna Sequences

Aptamers were first described almost 30 years ago, with the publication of three separate research papers describing how a randomized library of RNA sequences could be incubated with a target to find a sequence that specifically binds via van der Waals forces, covalent and hydrogen bonding, and not Watson Crick base pairing [...]

scholarly journals Crystal structure of 2-(2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ylidene)acetonitrile

2015 ◽  
Vol 71 (10) ◽  
pp. o792-o793
Author(s):  
K. Priya ◽  
K. Saravanan ◽  
S. Kabilan ◽  
S. Selvanayagam
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Crystal Packing ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Chair Conformation ◽  
Equatorial Orientation ◽  
Amino Group ◽  
Phenyl Rings

In the title 3-azabicyclononane derivative, C22H22N2, both the fused piperidine and cyclohexane rings adopt a chair conformation. The phenyl rings attached to the central azabicylononane fragment in an equatorial orientation are inclined to each other at 23.7 (1)°. The amino group is not involved in any hydrogen bonding, so the crystal packing is stabilized only by van der Waals forces.

scholarly journals 11-[Bis(trimethylsilyl)amino]-2,4-bis(trimethylsilyl)-7,8,9,10-tetrahydro-6H-cyclohepta[1,2-b]quinoline

IUCrData ◽  
2017 ◽  
Vol 2 (6) ◽  
Author(s):  
Ísmail Çelik ◽  
Mehmet Akkurt ◽  
Makbule Ekiz ◽  
Ahmet Tutar ◽  
Salih Ökten ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Title Compound ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Chair Conformation ◽  
Ring System ◽  
Maximum Deviation ◽  
Compound C ◽  
Trimethylsilyl Groups

In the title compound, C26H48N2Si4, the cycloheptane ring adopts a chair conformation, while the quinolinyl ring system is almost planar [maximum deviation = 0.040 (3) Å for one of the C atoms carrying a Me3Si group]. In the crystal, in the absence of classical hydrogen bonding, the packing is dominated by van der Waals forces. One of the N-bound trimethylsilyl groups is disordered by rotation about the C—SiMe3bond, and was modelled over two sets of sites in the ratio 0.873 (8):0.127 (8).

OxycodoneN-oxide

2012 ◽  
Vol 68 (11) ◽  
pp. o436-o438 ◽  
Author(s):  
Vijayakumar N. Sonar ◽  
Sean Parkin ◽  
Peter A. Crooks
Keyword(s):  
Hydrogen Bonding ◽  
Title Compound ◽  
Crystal Packing ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Pure Form ◽  
Chiral Center

The title compound, (5R,9R,13S,14S,17R)-14-hydroxy-3-methoxy-17-methyl-4,5-epoxymorphinan-6-oneN-oxide, C18H21NO5, has been prepared in a diastereomerically pure form by the reaction of oxycodone with 3-chloroperbenzoic acid and subsequent crystallization of the product from chloroform. The crystal packing shows that the molecule exhibits intramolecular O—H...O [D...A= 2.482 (2) Å] hydrogen bonding. In addition, there are weak intermolecular C—H...O interactions which, along with van der Waals forces, stabilize the structure. The new chiral center at the 17-position is demonstrated to beR.

2-Diethylamino-6-ethyl-6-methyl-3-phenylthieno[2,3-d]pyrimidin-4(3H)-one

2006 ◽  
Vol 62 (7) ◽  
pp. o2862-o2863
Author(s):  
Zheng-Dong Fang ◽  
Ming-Wu Ding
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Title Compound ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Stacking Interactions ◽  
Intermolecular Hydrogen Bonding ◽  
Compound C ◽  
Hydrogen Bonding Interactions ◽  
Π Stacking

In the title compound, C19H23N3OS, the two fused rings of the thieno[2,3-d]pyrimidin-4(3H)-one system are almost coplanar. The packing of the molecules in the crystal structure is determined by van der Waals forces. No intermolecular hydrogen-bonding interactions or π–π stacking interactions are present in the crystal structure.

Mechanical Behavior of Lightly Crosslinked Polyurethanes

1977 ◽  
Vol 50 (5) ◽  
pp. 934-944 ◽  
Author(s):  
S. Dzierża ◽  
J. Janáček
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Elevated Temperatures ◽  
Van Der Waals ◽  
Crosslinking Agent ◽  
Polymeric Materials ◽  
Van Der Waals Forces ◽  
Branch Points ◽  
Chain Entanglement ◽  
Polyurethane Elastomers

Abstract Polyurethane elastomers are a numerous group of polymeric materials of wide practical application. They are usually formed by polyaddition of diisocyanates with hydroxyl-terminated polyesters or polyethers in the presence of low molecular weight diols or diamines as chain extenders. One may consider urethane elastomers to be block copolymers, consisting of moderately flexible long linear polyester or polyether segments and relatively stiff segments of aromatic and urethane groups. The length and structure of each block can be easily controlled. Crosslinking by an excess of diisocyanate can occur only at the stiff segments, and the number of branch points can also be controlled. The properties of these elastomers can be widely changed using components of different structures and varying their quantitative ratios. They are the results of a combination of segment flexibility, crosslinking, chain entanglement, orientation of segments, hydrogen bonding and other van der Waals forces, as well as rigidity of aromatic units. In the urethane systems, hydrogen bonding and other van der Waals forces, play a much more pronounced role than in familiar olefin-derived elastomers. Although polyurethane elastomers have very good mechanical properties at room temperature, their application is strongly limited by rapid deterioration of properties which takes place at elevated temperatures. The decay of mechanical properties of polyurethane is caused by the breaking of hydrogen and other secondary bonds, as well as by the presence of relatively weak crosslinks that make up their network. The properties of polyurethanes at elevated temperatures may, perhaps, be improved by forming additional crosslinks, besides the typical ones. Some efforts concerning this problem have been published. The aim of our study was to obtain and check the properties of polyurethane elastomers having unsaturated bonds, on which some additional crosslinks were expected to be formed in the presence of a suitable crosslinking agent.

scholarly journals Crystal structure of di-μ-iodido-bis[bis(acetonitrile-κN)copper(I)]

2015 ◽  
Vol 71 (11) ◽  
pp. m189-m190
Author(s):  
Eva Rebecca Barth ◽  
Christopher Golz ◽  
Michael Knorr ◽  
Carsten Strohmann
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Title Compound ◽  
Crystal Packing ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Tetrahedral Coordination ◽  
Coordination Environment ◽  
Hydrogen Bonding Interactions ◽  
Distorted Tetrahedral Coordination

The title compound, [Cu2I2(CH3CN)4], exhibits a centrosymmetric Cu2I2core [Cu...Cu distance = 2.7482 (11) Å], the CuIatoms of which are further coordinated by four molecules of acetonitrile. The CuIatom has an overall distorted tetrahedral coordination environment evidenced byL—Cu—Langles (L= N or I) ranging from 100.47 (10) to 117.06 (2)°. The coordination geometries of the acetonitrile ligands deviate slightly from linearity as shown by Cu—N—C angles of 167.0 (2) and 172.7 (2)°. In the crystal, there are no significant hydrogen-bonding interactions present, so the crystal packing seems to be formed predominantly by van der Waals forces.

2-(2,4-Dichloro-6-methylphenoxy)-3-isopropyl-5,6,7,8-tetrahydrobenzothieno[2,3-d]pyrimidin-4(3H)-one

2007 ◽  
Vol 63 (3) ◽  
pp. o1142-o1144 ◽  
Author(s):  
Ai-Hua Zheng ◽  
Ji-Yin Long ◽  
Xiao-Hua Zeng ◽  
Hong-Mei Wang
Keyword(s):  
Hydrogen Bonding ◽  
Title Compound ◽  
Crystal Packing ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Ring System ◽  
Hydrogen Bonding Interaction ◽  
Compound C ◽  
Bonding Interaction

In the title compound C20H21Cl2N2O2S, the thienopyrimidine ring system is essentially planar. The crystal packing is stabilized by van der Waals forces and by an intermolecular C—H...O hydrogen-bonding interaction, which links the molecules into zigzag chains.

Self-Assembly of a Chiral Cubic Three-Connected Net from the High Symmetry Molecules C60 and SnI4

2020 ◽  
Author(s):  
Daniel B. Straus ◽  
Robert J. Cava
Keyword(s):  
Organic Synthesis ◽  
Self Assembly ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
High Symmetry ◽  
Molecular Chirality ◽  
Chiral Materials ◽  
Self Assembled ◽  
Chiral Centers

The design of new chiral materials usually requires stereoselective organic synthesis to create molecules with chiral centers. Less commonly, achiral molecules can self-assemble into chiral materials, despite the absence of intrinsic molecular chirality. Here, we demonstrate the assembly of high-symmetry molecules into a chiral van der Waals structure by synthesizing crystals of C<sub>60</sub>(SnI<sub>4</sub>)<sub>2</sub> from icosahedral buckminsterfullerene (C<sub>60</sub>) and tetrahedral SnI4 molecules through spontaneous self-assembly. The SnI<sub>4</sub> tetrahedra template the Sn atoms into a chiral cubic three-connected net of the SrSi<sub>2</sub> type that is held together by van der Waals forces. Our results represent the remarkable emergence of a self-assembled chiral material from two of the most highly symmetric molecules, demonstrating that almost any molecular, nanocrystalline, or engineered precursor can be considered when designing chiral assemblies.

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