scholarly journals Molecular self-assembly at nanometer scale modulated surfaces: trimesic acid on Ag(111), Cu(111) and Ag/Cu(111)

2014 ◽  
Vol 16 (23) ◽  
pp. 11265-11269 ◽  
Author(s):  
Mahdi Sadeghzadeh Baviloliaei ◽  
Lars Diekhöner
Keyword(s):  
Self Assembly ◽  
Room Temperature ◽  
The Self ◽  
Nanometer Scale ◽  
Trimesic Acid ◽  
Perfect Order

A modulated substrate strongly influences the self-assembly of trimesic acid: from disorder at room temperature to perfect order upon annealing.

Hydrothermal Syntheses, Crystal Structures, and Luminescent Properties of Two MnII Coordination Polymers: From Two-Fold Interpenetrated pcu Topological Net to Polycatenated 2D+2D→3D Framework

2015 ◽  
Vol 68 (2) ◽  
pp. 322 ◽  
Author(s):  
Wenlong Liu ◽  
Mengqiang Wu ◽  
Xueying Wang ◽  
Wei Wang ◽  
Dayu Liu ◽  
...  
Keyword(s):  
Dicarboxylic Acid ◽  
Coordination Polymers ◽  
Self Assembly ◽  
Room Temperature ◽  
Luminescent Properties ◽  
The Self ◽  
X Ray Diffraction ◽  
X Ray ◽  
3D Framework ◽  
Dimethyl Benzene

Using a hydrothermal synthesis, the self-assembly of MnII ions and 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene with two dicarboxylate ligands, 2-nitrobenzene-1,4-dicarboxylic acid (2-H2ata) and 5-methylbenzene-1,3-dicarboxylic acid (5-CH3-H2ip) constructed two interesting coordination polymers: [Mn(2-ata)(bimb)]n (1) and {[Mn(5-CH3-ip)(bimb)1.5]·2H2O}n (2), where bimb refers to 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene. Their structures were determined by single-crystal X-ray diffraction, elemental analysis, and infrared spectroscopy. Complex 1 exhibits a 2-fold interpenetrated pcu net. Complex 2 shows an unusual polycatenated 2D+2D→3D framework. In addition, the solid-state photoluminescent properties of 1 and 2 were investigated at room temperature.

Phase separation and selective guest–host binding in multi-component supramolecular self-assembly on Au(111)

2018 ◽  
Vol 54 (75) ◽  
pp. 10570-10573 ◽  
Author(s):  
Linghao Yan ◽  
Guowen Kuang ◽  
Nian Lin
Keyword(s):  
Phase Separation ◽  
Self Assembly ◽  
The Self ◽  
Trimesic Acid

We find a phase separation and selective guest–host inclusion in the self-assembly of trimesic acid, benzenetribenzoic acid and coronene on Au(111).

scholarly journals Adjacent functional group effects on the assembly of columnar liquid crystals

2020 ◽  
Vol 98 (7) ◽  
pp. 379-385
Author(s):  
Carson O. Zellman ◽  
Danielle Vu ◽  
Vance E. Williams
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Self Assembly ◽  
Room Temperature ◽  
Functional Group ◽  
The Self ◽  
Clearing Temperature ◽  
Crystal Phases ◽  
Potential Strategy ◽  
The Impact

Although the impact of individual functional groups on the self-assembly of columnar liquid crystal phases has been widely studied, the effect of varying multiple substituents has received much less attention. Herein, we report a series of dibenzo[a,c]phenazines containing an alcohol or ether adjacent to an electron-withdrawing ester or acid. With one exception, these difunctional mesogens form columnar phases. The phase behavior appeared to be dominated by the electron-withdrawing substituent; transition temperatures were similar to derivatives with these groups in isolation. In most instances, the addition of an electron-donating group ortho to an ester or acid suppressed the melting temperature and elevated the clearing temperature, leading to broader liquid crystal thermal ranges. This effect was more pronounced for derivatives functionalized with longer chain hexyloxy groups. These results suggest a potential strategy for controlling the phase ranges of columnar liquid crystals and achieving room temperature mesophases.

Self-assembly study of ammonium oleanolate and generation of gel– gold nanoparticle hybrid material

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Braja Gopal Bag ◽  
Subhajit Das
Keyword(s):  
Hybrid Material ◽  
Self Assembly ◽  
Room Temperature ◽  
Aqueous Ammonia ◽  
The Self ◽  
Solvent Mixtures ◽  
Optical Birefringence ◽  
Aqueous Solvent Mixtures ◽  
Aqueous Solvent ◽  
The Stability

A solution of oleanolic acid, a renewable nano-sized monohydroxy triterpenic acid in tetrahydrofuran, transformed into a gel instantly at room temperature on treatment with aqueous ammonia. Study of the self-assembly properties of ammonium oleanolate in water and aqueous solvent mixtures indicated that it self-assembles in the aqueous solvent mixtures forming gels in DMSO-water and DMF-water. Fibrillar networks with optical birefringence properties were observed by polarized optical microscopy. Scanning electron microscopy of the dried gel samples indicated fibrillar networks with fibers of nano to micrometer diameters. The thermodynamic parameters calculated from the gel to sol transition temperatures indicated the stability of the gels. A gel-gold nanoparticles hybrid material has also been prepared and characterized by HRTEM, EDX, SAED and surface Plasmon resonance studies.

Noble metal nanoclusters-decorated NiFe layered double hydroxide superstructure as nanoreactors for selective hydrogenation catalysis

Nanoscale ◽  
2020 ◽  
Vol 12 (34) ◽  
pp. 17780-17785
Author(s):  
Hao Zhang ◽  
Xiaoying Guo ◽  
Xun Wang
Keyword(s):  
Selective Hydrogenation ◽  
Self Assembly ◽  
Building Blocks ◽  
The Self ◽  
Nanometer Scale ◽  
Metal Nanoclusters ◽  
The Core ◽  
Core Issue ◽  
Double Hydroxide ◽  
Noble Metal Nanoclusters

The ability to conduct the self-assembly of nanometer-scale building blocks is the core issue in achieving “bottom-up” fabrications of desired superstructures.

Porphyrin self-assembly as template for RNA?

2001 ◽  
Vol 05 (09) ◽  
pp. 691-701 ◽  
Author(s):  
GERLINDE BISCHOFF ◽  
ROBERT BISCHOFF ◽  
SIEGFRIED HOFFMANN
Keyword(s):  
Self Assembly ◽  
Electrostatic Interactions ◽  
Room Temperature ◽  
Helical Structure ◽  
Scanning Force Microscopy ◽  
The Self ◽  
Scanning Calorimetry ◽  
Low Salt ◽  
Aqueous Conditions ◽  
Increasing Temperature

The self-assembly of chiral porphyrin molecules HpD (hematoporphyrin IX derivative) has been shown to form helical fibers in low salt aqueous conditions. The spectroscopic (UV and circular dichroism (CD)), thermodynamic (Tm, differential scanning calorimetry (DSC)) and microscopic (light and scanning force microscopy (SFM)) examinations of the HpD properties were performed individually and in the presence of nucleic acid double strands (15–60 °C, 0–50 mM NaCl ). The asymmetric HpD molecules themselves at room temperature show sharp positive or negative CD signals, which increase enormously with HpD concentration. The data show strong evidence for the external self-stacking interaction of HpD , pure and in the presence of polynucleotides. At low salt concentration (<40 mM NaCl , pH 7) the spectra change completely by increasing the temperature. At 35 to 40 °C RNA-similar spectra of the pure HpD self-assemblies (without nucleic acids) occur. At higher temperatures the aggregates become unstable and break off. At room temperature the helical structure of the fibers could be visualized by SFM investigations. Molecular modeling analysis offers dynamic arrangements of the self-assemblies from stacks to spiral-like superstructures with increasing temperature. Hydrogen bonding, electron transferring and electrostatic interactions determine the shape of the proposed highly flexible arrangements. Moreover, the interrelation between the HpD stacks and the helix of the polynucleotides was studied. The calculated low transition energies indicate the importance of these structures as a crossing link. All data are discussed in favor of a hypothetical evolutionary matrix role in porphyrin self-assembly for RNA.

GROWTH AND CHARACTERIZATION OF ATOMIC AND NANOMETER SCALE WIRES ON THE SILICON SURFACE

2000 ◽  
Vol 07 (05n06) ◽  
pp. 555-560 ◽  
Author(s):  
J. NOGAMI
Keyword(s):  
Transport Properties ◽  
Electronic Properties ◽  
Self Assembly ◽  
Silicon Surface ◽  
Growth Behavior ◽  
The Self ◽  
Nanometer Scale ◽  
Semiconductor Surfaces ◽  
Length Scales

Growth of metals on semiconductor surfaces can result in the self-assembly of a variety of 1D or 2D structures whose lateral dimensions range from one atom to tens of atoms. Over this range in length scales, STM gives information about the structure, the growth behavior and the electronic properties of these small structures. STM and STS data on several different systems are presented. In addition, ongoing and future efforts to measure the transport properties of these small structures are described.

TERRACE INDUCED HOMOCHIRAL SELF-ASSEMBLY OF ZINC PHTHALOCYANINEON COPPER (111) SURFACE

2016 ◽  
Vol 23 (06) ◽  
pp. 1650047
Author(s):  
XIN SONG ◽  
HUIHUI KONG ◽  
LACHENG LIU ◽  
XIAOQING LIU ◽  
MINGDONG DONG ◽  
...  
Keyword(s):  
Self Assembly ◽  
Growth Process ◽  
Room Temperature ◽  
Organic Molecules ◽  
The Self ◽  
Step Edge ◽  
Suitable Method ◽  
Large Area ◽  
Molecular Assemblies ◽  
Lower Terrace

It is still a challenge to find a suitable method to fabricate a well-defined homochiral surface from achiral molecules, and one of the possible methods is to modify surfaces with organic molecular assemblies. Large-area chiral self-assembly nanostructures have been observed at room temperature by depositing ZnPc molecules on a Cu(111) surface. The growth process has been investigated. ZnPc molecules get adsorbed first at the terrace steps, and then extend over the lower terrace until the whole terrace is covered with ZnPc molecules; such growth process would be stopped when the self-assembly nanostructure run into a decorated upper terrace step edge. We found that the terrace steps with specific directions with respect to the close-packed directions of the substrate can induce homochiral self-assembly on the lower terraces. So we can propose a possible way to fabricate a well-defined homochiral surface from achiral organic molecules.

scholarly journals Controlled Morphological Changes in Self-Assembled Structures Formed by Fmoc Variants of Threonine and Serine

2021 ◽  
Author(s):  
Vivekshinh Kshtriya ◽  
Bharti Koshti ◽  
Nidhi Gour
Keyword(s):  
Self Assembly ◽  
Room Temperature ◽  
Morphological Changes ◽  
The Self ◽  
Temperature Conditions ◽  
Morphological Transitions ◽  
Concentration Changes ◽  
Higher Temperature ◽  
Self Assembled ◽  
First Time

<p>We report for the very first time the self-assembly of<a> </a>Fmoc variant 2-(9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(tert-butoxy)butanoic acid of threonine (<b>Fmoc-Thr(tbu)-OH</b>) and <a>of serine (</a><b>Fmoc-</b><b>Ser(tbu)-OH</b>. The self-assembled structure formation of Fmoc variants of threonine and serine were examined under varying concentration and temperature conditions..Our studies reveal that the self-assembled structures formed by <b>Fmoc-Thr(tbu)-OH </b>and <b>Fmoc-Ser(tbu)-OH </b>reveal morphological transitions at the supramolecular level as we alter its concentration and temperature. <b>Fmoc-Thr(tbu)-OH </b>self-assembles to sphere at lower concentration which changes to dumb-bell shapes at higher concentration under room temperature conditions. When the solution at lower concentration is heated the spheres changes to rods while the dumb bell shapes at higher concentrations change to elongated dumb-bell-rod like morphologies. <b>Fmoc-Ser(tbu)-OH </b>on<b> </b>the other hand give flower like morphologies at lower concentration which changes to long rods at higher concentration. On heating at higher temperature 70 <sup>ο</sup>C flower-like structures change to small rods while the long rods obtained at higher concentration changes to big flower-like structures. The controlled morphological changes noted in the modified single amino acids is very interesting and pave the way for the design of novel self-assembled architectures for applications in material science and nanotechnology.</p>

scholarly journals Room-temperature surface-assisted reactivity of a melanin precursor: silver metal–organic coordination versus covalent dimerization on gold

Nanoscale ◽  
2018 ◽  
Vol 10 (35) ◽  
pp. 16721-16729 ◽  
Author(s):  
F. De Marchi ◽  
G. Galeotti ◽  
M. Simenas ◽  
E. E. Tornau ◽  
A. Pezzella ◽  
...  
Keyword(s):  
Self Assembly ◽  
Room Temperature ◽  
The Self ◽  
Metal Organic ◽  
Covalent Dimerization ◽  
Silver Metal ◽  
Temperature Surface

The surface drives the self-assembly of a catechol–indole molecule, triggering metal–organic coordination on silver and dimerization on gold at room temperature.

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