Search results for "assembly"
showing 10 items of 768 documents
Generation of [2×2] Grid Metallosupramolecular Architectures from Preformed Ditopic Bis(acylhydrazone) Ligands and through Component Self‐Assembly
2007
Ditopic bis(acylhydrazone) ligands, derived from the reactions of carbohydrazides with 2-phenylpyrimidine-4,6-dicarbaldehyde and designed for grid formation with octahedrally coordinating transition-metal ions, exhibit a varied coordination chemistry depending upon the degree of their deprotonation. The neutral acylhydrazones are relatively poor ligands and are seemingly involved in multiple, labile complexation equilibria varying with the solvent and the particular metal salt in solution; nevertheless, grid complexes of different forms can be isolated in the solid state. Although only limited study has been made of the singly deprotonated ligands, grid species appear to be much more readil…
Efficient Self-Assembly of Di-, Tri-, Tetra-, and Hexavalent Hosts with Predefined Geometries for the Investigation of Multivalency
2015
Coordination-driven self-assembly of differently shaped di- to hexavalent crown-ether host molecules is described. A series of [21]crown-7- and [24]crown-8-substituted bipyridine and terpyridine ligands was synthetized in a "toolbox" approach. Subsequent coordination to 3d transition metal and ruthenium(II) ions provides an easy and fast access to host assemblies with variable valency and pre-defined orientations of the crown-ether moieties. Preliminary isothermal calorimetry (ITC) titrations provided promising results, which indicated the host complexes under study to be suitable for the future investigation of multivalent and cooperative binding. The hosts described herein will also be su…
Sterically controlled self-assembly of tetrahedral M(6)L(4) cages via cationic N-donor ligands.
2014
Tripodal cationic N-donor ligands exhibit sterically controlled self-assembly of tetrahedral M6L4 coordination cages that promote selective anion encapsulation (PF6(-)OTf(-)) in the solid state. The described method is a potential template for stepwise assembly of hetero-ligand coordination cages and polymers.
Layer-by-layer deposited multilayer assemblies of polyelectrolytes and proteins: from ultrathin films to protein arrays
2008
We have recently introduced a new method of creating ultrathin films of polyelectrolytes based on the electrostatic attraction between opposite charges. Multilayer assemblies are adsorbed in a layer-by-layer fashion from aqueous solutions of the polymers. The total film thickness can easily be adjusted by varying the ionic strength of the solution. Here, we report on the temperature stability and the water content of the multilayer assemblies. Furthermore, we have extended our concept to the incorporation of protein layers into films of synthetic polyelectrolytes. The well established system biotin/streptavidin was used to construct such multilayers, also by biospecific recognition. Adsorpt…
Molecular self-assembly on an insulating surface: interplay between substrate templating and intermolecular interactions
2012
We report on molecular self-assembly of biphenyl-4,4'-dicarboxylic acid (BPDCA) on CaCO3(10 (1) over bar4) under ultra-high vacuum conditions. Two-dimensional, ordered islands are obtained upon deposition at room temperature, coexisting with a streaky structure that is ascribed to individual, mobile molecules forming a two-dimensional gas-like phase. High-resolution non-contact atomic force microscopy (NC-AFM) images of the molecular islands reveal an ordered inner structure that is dominated by rows of molecules aligned side by side running along the [(42) over bar 61] crystallographic direction. A detailed analysis of these rows exhibits inter-row distances that are multiples of the calci…
Kinetically Controlled Sequential Growth of Surface-Grafted Chiral Supramolecular Copolymers.
2016
We report a facile strategy to grow supramolecular copolymers on Au surfaces by successively exposing a surface-anchored monomer to solutions of oppositely charged peptide comonomers. Charge regulation on the active chain end of the polymer sufficiently slows down the kinetics of the self-assembly process to produce kinetically trapped copolymers at near-neutral pH. We thereby achieve architectural control at three levels: The β-sheet sequences direct the polymerization away from the surface, the height of the supramolecular copolymer brushes is well-controlled by the stepwise nature of the alternating copolymer growth, and 2D spatial resolution is realized by using micropatterned initiatin…
A New Structural Motif for an Enantiomerically Pure Metallosupramolecular Pd4L8Aggregate by Anion Templating
2014
An enantiomerically pure BINOL-based bis(3-pyridyl) ligand 1 assembles into a homochiral [Pd4(1)8] complex upon coordination to tetravalent PdII ions. The formation of this aggregate is templated by two tetrafluoroborate counterions that are encapsulated in two peripheral cavities. The resulting structure is a new structural motif for this kind of metallosupramolecular assemblies that arranges the palladium ions in a distorted tetrahedral fashion and forces ligand 1 to adopt two different conformations. Both phenomena are unique and cause an overall three-dimensional structure that has another confined, chiral, and hydrophilic central cavity.
Enantioselective self-assembly of antiferromagnetic hexacopper(ii) wheels with chiral amino acid oxamates
2013
The Cu(2+)-mediated self-assembly of oxamato-based ligands derived from either the (S)- or (R)-enantiomers of the amino acid valine leads to the formation of two antiferromagnetically coupled homochiral anionic hexacopper(II) wheels in the presence of templating tetramethylammonium countercations.
Guest-Induced Folding and Self-Assembly of Conformationally Adaptive Macrocycles into Nanosheets and Nanotubes
2017
A conformationally adaptive macrocycle is presented, namely zorb[4]arene, which exists in multiple conformations in the uncomplexed state. The binding cavity of zorb[4]arene is concealed, either due to a collapsed conformation or by self-inclusion. The zorb[4]arene with long alkyl chains manifests itself with surprisingly low melting point and thus exist as an oil at room temperature. Binding of a guest molecule induces the folding and conformational rigidity of zorb[4]arene and leads to well-defined three-dimensional structures, which can further self-assemble into nanosheets or nanotubes upon solvent evaporation, depending on guest molecules and the conformations they can induce.
Self-Assembled Polymers Based on bis-Tetra-Urea Calix[4]arenes Connected via the Wide Rim
2008
Six double calixarenes were synthesised in which two tetra-urea calix[4]arenes are linked by a rigid spacer between the urea functions at their wide rim. The dimerisation of their tetra-urea parts leads to hydrogen-bonded polymeric assemblies in apolar solvents. The addition of the stoichiometric amount of a tetra-tosylurea calix[4]arene disrupts the polymeric structures due to the preferred formation of heterodimeric capsules between tetra-aryl and tetra-tosylurea calix[4]arenes. The existence of polymeric assemblies was further established by AFM studies on spin-coated samples.