Supramolecular Construction of Bidentate Ligands Through Self‐assembly by Hydrogen Bonding

2021 ◽  
pp. 1-25
Author(s):  
Felix Bauer ◽  
Bernhard Breit
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Bidentate Ligands

Self-assembly of bidentate ligands for combinatorial homogeneous catalysis based on an A-T base pair model

2006 ◽  
Vol 78 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Bernhard Breit ◽  
Wolfgang Seiche
Keyword(s):  
Hydrogen Bonding ◽  
Metal Complex ◽  
Base Pair ◽  
Self Assembly ◽  
Bidentate Ligands ◽  
Metal Complex Catalysis ◽  
System A ◽  
Pair Model ◽  
Excellent Activity ◽  
Monodentate Ligands

A new concept for generation of chelating ligand libraries for homogeneous metal complex catalysis based on self-assembly is presented. Thus, self-assembly of structurally simple monodentate ligands in order to give structurally more complex bidentate ligands is achieved employing hydrogen bonding. Based on this concept and on the 2-pyridone/hydroxypyridine tautomeric system, a new rhodium catalyst was identified which operated with excellent activity and regioselectivity upon hydroformylation of terminal alkenes. In order to generate defined unsymmetrical heterodimeric ligands, an A-T base pair analog-the aminopyridine/isoquinolone system-was developed which allows for complementary hydrogen bonding. Based on this platform, a 4 x 4 phosphine ligand library was screened in the course of the rhodium-catalyzed hydroformylation of 1-octene. A catalyst operating with outstanding activity and regioselectivity in favor of the linear aldehyde was discovered.

scholarly journals Self-Assembled Bimetallic Aluminum-Salen Catalyst for the Cyclic Carbonates Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4097
Author(s):  
Wooyong Seong ◽  
Hyungwoo Hahm ◽  
Seyong Kim ◽  
Jongwoo Park ◽  
Khalil A. Abboud ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Reaction Pathway ◽  
Kinetic Studies ◽  
Cyclic Carbonate ◽  
Reaction Conditions ◽  
Formation Reaction ◽  
X Ray ◽  
Carbonate Formation ◽  
Salen Aluminum

Bimetallic bis-urea functionalized salen-aluminum catalysts have been developed for cyclic carbonate synthesis from epoxides and CO2. The urea moiety provides a bimetallic scaffold through hydrogen bonding, which expedites the cyclic carbonate formation reaction under mild reaction conditions. The turnover frequency (TOF) of the bis-urea salen Al catalyst is three times higher than that of a μ-oxo-bridged catalyst, and 13 times higher than that of a monomeric salen aluminum catalyst. The bimetallic reaction pathway is suggested based on urea additive studies and kinetic studies. Additionally, the X-ray crystal structure of a bis-urea salen Ni complex supports the self-assembly of the bis-urea salen metal complex through hydrogen bonding.

scholarly journals Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4705
Author(s):  
Boer Liu ◽  
Xi Chen ◽  
Glenn A. Spiering ◽  
Robert B. Moore ◽  
Timothy E. Long
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Random Copolymer ◽  
Thermomechanical Properties ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Central Block ◽  
Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

Recording the Self-Assembly Behavior of Nanomaterials Directed by Hydrogen Bonding

2021 ◽  
Author(s):  
Ganghuo Pan ◽  
Jie Leng ◽  
Liye Deng ◽  
Liwen Xing ◽  
Rui Feng
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
The Self ◽  
Assembly Behavior

Self-assembly of CdSe/CdS quantum dots by hydrogen bonding on Au surfaces for photoreception

2003 ◽  
pp. 2278 ◽  
Author(s):  
Jing Tang ◽  
Henrik Birkedal ◽  
Eric W. McFarland ◽  
Galen D. Stucky
Keyword(s):  
Quantum Dots ◽  
Hydrogen Bonding ◽  
Self Assembly ◽  
Cds Quantum Dots

Self-assembly of 2,6-dimethylpyridine on Cu(110) directed by weak hydrogen bonding

2007 ◽  
Vol 601 (16) ◽  
pp. L91-L94 ◽  
Author(s):  
Junseok Lee ◽  
Daniel B. Dougherty ◽  
John T. Yates
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Weak Hydrogen Bonding

Hydrogen-Bonding Layer Protecting Polyelectrolyte Capsules and Its Mechanical Property Study with Atomic Force Microscope

2008 ◽  
Vol 8 (6) ◽  
pp. 2996-3002 ◽  
Author(s):  
Liqin Ge ◽  
Xing Wang ◽  
Long Ba ◽  
Zhongze Gu
Keyword(s):  
Hydrogen Bonding ◽  
Atomic Force Microscope ◽  
Elastic Deformation ◽  
Self Assembly ◽  
Laser Scanning ◽  
Confocal Laser ◽  
Bonding Layer ◽  
Layer By Layer ◽  
Assembly Method ◽  
Atomic Force

The hydrogen-bonding multilayered polyelectrolyte capsules with sizes around 6 μm were fabricated by layer-by-layer self-assembly method. The morphology of the obtained capsules was observed with Scanning Electron Microscope (SEM), Confocal Laser Scanning Microscope (CLSM) and Atomic Force Microscope (AFM), respectively. The elastic properties of the capsules were studied with AFM. The capsule was pressed by cantilever with different lengths, a glass bead glued at the end of the cantilever. The force curves were measured on the capsule in air. The Young's modulus of the capsule was obtained (E = 170 MPa for the loading). Results show that this model can predict the elastic deformation of the microcapsule. The accuracy of the elastic deformation of polymer capsule can be ensured using a cantilever of mediate stiffness. Our results show that the existence of the hydrogen-bonding layer makes the multilayered polyelectrolyte harder in comparison with the pure multilayered polyelectrolyte capsules.

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