Search results for " assembly."

Kinetically Trapped Supramolecular Assembly of Perylene Dianhydride Derivative in Methanol: Optical Spectra, Morphology, and Mechanisms.

2016

Supramolecular self-assembly has attracted increasing attention as a breakthrough methodology in the fields of nanoscience and nanotechnology. Herein, a perylene dianhydride derivative (TP-PDA) self-assembles into well-defined nanospheres through a nucleation-growth process. The mechanisms of this process were explored by using spectral analysis, dynamic light scattering (DLS), and scanning electron microscopy (SEM). In situ DLS and in situ SEM both revealed that the size of the aggregated nanospheres increases with time until the formation of equilibrium H-aggregates. This shows that TP-PDA undergoes a kinetically trapped assembly with a rapid transformation into the thermodynamically favo…

The key role of hydrogen bonding in the nuclearity of three copper(II) complexes with hydrazone-derived ligands and nitrogen donor heterocycles

2011

International audience; Three new Cu(II) complexes of formula [Cu(L1)(pyz)(CH3OH)]ClO4 (1), [Cu(L1)(4,4′-bpy)(ClO4)]·0.5H2O (2) and [{Cu(L2)(ClO4)}2(μ-4,4′-bpy)] (3) have been synthesised by using pyrazine (pyz) and 4,4′-bipyridine (4,4′-bpy) and tridentate O,N,O-donor hydrazone ligands, L1H and L2H, obtained by the condensation of 1,1,1-trifluoro-2,4-pentanedione with salicyloylhydrazide and benzhydrazide, respectively. The ligands and their complexes have been characterized by elemental analyses, FT-IR, and UV–Vis spectroscopies. Single crystal X-ray structure analysis evidences the metal ion in a slightly deformed square pyramidal geometry in all the complexes. However complexes 1 and 2 …

Exploring the 2,2′-Diamino-5,5′-bipyrimidine Hydrogen-Bonding Motif: A Modular Approach to Alkoxy-Functionalized Hydrogen-Bonded Networks

1998

The programmed self-association of 2,2’-diamino-4,4’-dialkoxy-5,5’-bipyrimidines allows for the de novo construction of alkoxy-functionalized H-bonded ribbons and sheets as evidenced by X-ray crystallographic analysis. The data provide insight into the interplay of the different structural and interactional features of the molecular components to the generation of the supramolecular assembly. Hydrophobicity of the didodecyl side chains of 4c leads to the dominance of the H-bonding factor, resulting in the formation of a fully interconnected array. These results define the utility of the of 2,2’-diamino-4,4’-dialkoxy-5,5’-bipyrimidines as a potential scaffold for the attachment of electro- o…

"Comment on ""Non-symmetric substituted ureas locked in an (E,Z) conformation: an unusual anion binding via supramolecular assembly"" by M. Olivari, …

2014

We propose another point of view on the type of hydrogen bonded complexes that were described in this journal (M. Olivari et al., New J. Chem., 2013, 37, 663). The main difference is the molecular geometry and breakage of the intramolecular hydrogen bond during association. The current comment is to highlight mentioned aspects and to point out that in some cases the interpretation may not be straightforward due to the simultaneous effects associated with complexation.

Assembly and encapsulation of coordination tectons driven by hydrogen-bondingand space-filling

2001

[FR] Le composé ¿Fe(LI)3¿2¿Fe(H2O)6¿(ClO4)6 (2), LI = 1,10-phénanthroline-5,6-dione, a été synthétisé et caractérisé. La structure cristalline 2 est définie par un assemblage bidimensionnel non covalent, peu commun, constitué par des tectons chiraux ¿Fe(LI)3¿2+, assemblés par des cations ¿Fe(H2O)6¿2+ encapsulés dans des cages. Ces cages sont formées par 12 liaisons hydrogène établies entre les molécules d¿eau coordinées et les groupes dione appartenant à six molecules chirales ¿Fe(LI)3¿2+ ¿, ¿ alternées.

Nouvelles perspectives concernant la structure et la fonction du domaine carboxyl terminal de Hfq

2015

Accumulating evidence indicates that RNA metabolism components assemble into supramolecular cellular structures to mediate functional compartmentalization within the cytoplasmic membrane of the bacterial cell. This cellular compartmentalization could play important roles in the processes of RNA degradation and maturation. These components include Hfq, the RNA chaperone protein, which is involved in the post-transcriptional control of protein synthesis mainly by the virtue of its interactions with several small regulatory ncRNAs (sRNA). The Escherichia coli Hfq is structurally organized into two domains. An N-terminal domain that folds as strongly bent β-sheets within individual protomers to…

On the thermo-mechanical behaviour of the IFMIF target assembly under steady state and transient operative scenarios

Analysis of the thermo-mechanical behaviour of IFMIF target assembly integrated with its support framework

2014

On the computational assessment of the IFMIF-EVEDA Target Assembly thermal behaviour

2011

ISWI Regulates Higher-Order Chromatin Structure and Histone H1 Assembly In Vivo

2007

Imitation SWI (ISWI) and other ATP-dependent chromatin-remodeling factors play key roles in transcription and other processes by altering the structure and positioning of nucleosomes. Recent studies have also implicated ISWI in the regulation of higher-order chromatin structure, but its role in this process remains poorly understood. To clarify the role of ISWI in vivo, we examined defects in chromosome structure and gene expression resulting from the loss of Iswi function in Drosophila. Consistent with a broad role in transcriptional regulation, the expression of a large number of genes is altered in Iswi mutant larvae. The expression of a dominant-negative form of ISWI leads to dramatic a…