Self-assembled “Supra-molecular” Structures via Hydrogen Bonding and Aromatic/Aliphatic Microphase Separation on Different Length Scales in Symmetric-Tapered Bisamides

2004 ◽  
Vol 16 (6) ◽  
pp. 1014-1025 ◽  
Author(s):  
Chenchen Xue ◽  
Shi Jin ◽  
Xing Weng ◽  
Jason J. Ge ◽  
Zhihao Shen ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Microphase Separation ◽  
Molecular Structures ◽  
Length Scales ◽  
Self Assembled

Fundamental theoretical and practical investigations of the polymorph formation of small amphiphilic molecules, their co-crystals and salts

2017 ◽  
Vol 232 (1-3) ◽  
Author(s):  
Thomas Martin ◽  
Paul Niemietz ◽  
Dominik Greim ◽  
Philipp Ectors ◽  
Jürgen Senker ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Benzoic Acid ◽  
Microphase Separation ◽  
Process Variations ◽  
Practical Investigations ◽  
Molecular Structures ◽  
Model Systems ◽  
Coordination Polyhedra ◽  
Π Stacking ◽  
General Importance

AbstractThe amphiphilic nature of benzoic acid, benzoates and benzamide causes an unexpected rich polymorphism. Featuring rather rigid and small molecular structures these compounds are ideal model systems for gaining a more fundamental understanding of molecular polymorphism by systematic and concerted investigations. The hydrophilic head allows for hydrogen bonding while the phenyl moiety gives rise to various π-stacking modes. Variations of hydrogen bonding versus π-stacking modes give rise to four polymorphs of benzamide. The central synthon in all phases is a dimer where hydrophilic units form double hydrogen bonds. As suggested by MD simulations of the nucleation process, variations of the crystallization conditions trigger whether the first self-assembly occurs via the hydrophilic head or the hydrophophic tail groups. Based on NMR crystallographic investigations for the co-crystallization of benzamide with benzoic acid, we observed yet another variation of the balance of the two dominating intermolecular interactions leading to the formation of a 1:1 co-crystal. The average crystal structure resembles the packing motive of pure benzoic acid with alternating ribbons of homogenous benzamide and benzoic acid dimers. For alkali-benzoate salts a coordination dilemma arises that is of general importance for many active pharmaceutical ingredients (APIs). A 1:1 stoichiometry requires condensation of coordination polyhedra of small inorganic cations which in turn causes steric stress that varies with the relative volumes of cation and anion. Interestingly, one way of resolving the dilemma is microphase separation which is directly related to the amphiphilic character of benzoate.

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.

scholarly journals Exciton Fine-Structure Splitting in Self-Assembled Lateral InAs/GaAs Quantum-Dot Molecular Structures

ACS Nano ◽  
2015 ◽  
Vol 9 (6) ◽  
pp. 5741-5749 ◽  
Author(s):  
Stanislav Fillipov ◽  
Yuttapoom Puttisong ◽  
Yuqing Huang ◽  
Irina A. Buyanova ◽  
Suwaree Suraprapapich ◽  
...  
Keyword(s):  
Fine Structure ◽  
Quantum Dot ◽  
Molecular Structures ◽  
Fine Structure Splitting ◽  
Structure Splitting ◽  
Self Assembled ◽  
Gaas Quantum Dot

Exploring the 3D Structure and Defects of a Self-Assembled Gold Mesocrystal by Coherent X-ray Diffraction Imaging

Nanoscale ◽  
2021 ◽  
Author(s):  
Jerome Carnis ◽  
Felizitas Kirner ◽  
Dmitry Lapkin ◽  
Sebastian Sturm ◽  
Young Yong Kim ◽  
...  
Keyword(s):  
Nanostructured Materials ◽  
Crystallographic Orientation ◽  
3D Structure ◽  
Structural Heterogeneity ◽  
X Ray Diffraction ◽  
Length Scales ◽  
X Ray ◽  
Diffraction Imaging ◽  
Self Assembled

Mesocrystals are nanostructured materials consisting of individual nanocrystals having a preferred crystallographic orientation. On mesoscopic length scales, the properties of mesocrystals are strongly affected by structural heterogeneity. Here, we report...

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