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Marc Schmutz

Publications and source records attributed to Marc Schmutz.

13 recordsLinked to original sources
PubMed2006

Tuning the thermotropic and lyotropic properties of liquid-crystalline terpyridine ligands.

A rational synthetic strategy is developed to provide compact and simple terpyridine (terpy) mesogens that show liquid-crystallinity both as pure compounds and in organic solution (amphotropic compound). The use of a central 4-methyl-3,5-diacylaminophenyl platform equipped with two lateral aromatic rings, each bearing three appended aliphatic chains, allows connection of a 2,2':6',2''-terpyridine fragment through a polar group such as an ester, amide, or flat conjugated alkyne linker. For the T(12)ester and T(12)amide scaffolds, the mesophase is best described as a lamellar phase, in which the molecules self-assemble into columnar stacks held together in layers. In the T(12)amide case, the additional amide link results in significant stabilization of the lamellar phase. The driving forces for the appearance of columnar ordering are the hydrogen-bonding interactions of the amide groups, which induce head-to-tail pi-stacking of the terpy subunits. Replacing the polar linker by a nonpolarized but linear alkyne spacer, as in the T(12)ethynyl compound, provides a columnar mesophase organized in a rectangular lattice of p2gg symmetry. In this arrangement, two nondiscotic molecules arranged into dimers by hydrogen bonding and pi-pi stacking pile up in a head-to-tail manner to form columns. In addition, the T(12)amide compound proves to be an excellent gelator of cyclohexane, linear alkanes, and DMSO. The resulting robust and transparent gels are birefringent and formed by large aggregates that are readily aligned by shear-flow. TEM and freeze-fracture microscopy reveal that the gels have an original layered morphology made of fibers.

Amides↗
PubMed2006

Highly luminescent gels and mesogens based on elaborated borondipyrromethenes.

Supramolecular gels and liquid-crystalline materials containing borondipyrromethene (F-Bodipy) are a new class of highly luminescent materials built by attachment of long-chain alkoxydiacylamido scaffoldings to boradiazaindacene templates. Robust gels were formed in nonane, and luminescence spectroscopy was used to probe the aggregation processes of the flat indacene cores. Coincidently, columnar mesophase was obtained from the pure material over a wide temperature range, allowing textural observations by fluorescence microscopy.

Journal Article↗
PubMed2006

Membrane properties of branched polyprenyl phosphates, postulated as primitive membrane constituents.

We have postulated earlier that the highly branched isoprenoid alkanes, which are distributed widely in many sediments, may have been derived from the corresponding branched polyprenyl phosphates, potentially present in biomembranes in primitive organisms. These polyprenyl-branched polyprenyl phosphates might be derived by a simple alkylation from non-substituted polyprenyl phosphates, which we postulate to be the precursors of all membrane terpenoids. We have now synthesized a series of 6-(poly)prenyl-substituted polyprenyl phosphates and studied the formation of vesicles from these phosphates, as a function of the substituted-chain length, the position of the double bond, and pH. Nine of the branched polyprenyl phosphates containing 20-30 C-atoms do form vesicles at a 'physiological' pH; the lipophilicity/hydrophilicity ratio is as expected an important factor. We have also studied the water permeability through membranes of these branched polyprenyl phosphate vesicles by our stopped-flow/light-scattering method. These highly branched polyprenyl phosphates can more effectively reduce the water permeability than non-substituted polyprenyl phosphates: the vesicles formed by the former are more stable against mechanical stress. This reinforces our hypothesis about the origin of the sedimentary polyprenyl-substituted polyprene hydrocarbons.

Cell Membrane↗
PubMed2005

Hierarchical self-assembly of a bow-shaped molecule bearing self-complementary hydrogen bonding sites into extended supramolecular assemblies.

The bow-shaped molecule 1 bearing a self-complementary DAAD-ADDA (D=donor A=acceptor) hydrogen-bonding array generates, in hydrocarbon solvents, highly ordered supramolecular sheet aggregates that subsequently give rise to gels by formation of an entangled network. The process of hierarchical self-assembly of compound 1 was investigated by the concentration and temperature dependence of UV-visible and (1)H NMR spectra, fluorescence spectra, and electron microscopy data. The temperature dependence of the UV-visible spectra indicates a highly cooperative process for the self-assembly of compound 1 in decaline. The electron micrograph of the decaline solution of compound 1 (1.0 mM) revealed supramolecular sheet aggregates forming an entangled network. The selected area electronic diffraction patterns of the supramolecular sheet aggregates were typical for single crystals, indicative of a highly ordered assembly. The results exemplify the generation, by hierarchical self-assembly, of highly organized supramolecular materials presenting novel collective properties at each level of organization.

Journal Article↗
PubMed2003

Preparation and evaluation of a new class of gene transfer reagents: poly(-alkylaminosiloxanes).

We report the evaluation of poly(-alkylaminosiloxane) as a novel class of polycationic DNA carriers. Controlled hydrolysis of mono- and di-aminoalkylmethyldimethoxysilane provided a wide range of defined oligomeric mixtures. Basic hydrolysis conditions yielded mixtures composed mainly of cyclic and long linear oligomers, while under acidic conditions mainly short-linear oligomers were derived. They all efficiently interacted with plasmid DNA as revealed by electron microscopy and DNA retardation assays. However, only diamine-based oligomers prepared under basic conditions were able to mediate substantial levels of DNA transfection in human HeLa cells. SiDA1b, prepared by basic hydrolysis of 3-(2-aminoethylamino)propyl-methyl-dimethoxysilane, was found to be at least as efficient as the frequently used cationic transfection agents DOTAP and polyethylenimine (PEI). The transfection activity was sensitive to bafilomycin A1, suggesting a mechanism that depends on proton capture during the acidification process associated with endocytosis.

Animals↗
PubMed2002

The bromodomain mediates transcriptional intermediary factor 1alpha -nucleosome interactions.

Nuclear histone acetyltransferases, DNA-dependent ATPases, and transcriptional intermediary factors (TIFs) all harbor a distinct structural module known as the bromodomain (BrD). Although the BrD can interact with histones H3 and H4 and their acetylated N-terminal tails in vitro, its function in a chromosomal environment remains elusive. We used the nuclear receptor coregulator TIF1alpha, a protein kinase that associates tightly with euchromatin, to analyze the properties of the BrD in a nucleosomal environment in vitro. Here, we report that TIF1alpha-chromatin association is direct and involves DNA and nucleosome interactions mediated by the BrD. Mutation of the BrD signature peptide, PMDL, abolishes DNA binding and disrupts BrD-nucleosome interactions. Based on our results, we propose that the BrD plays a critical role in vivo by directing transregulators to their cognate location on nucleosomal DNA.

Amino Acid Sequence↗
PubMed2002

Helical self-organization and hierarchical self-assembly of an oligoheterocyclic pyridine-pyridazine strand into extended supramolecular fibers.

The synthesis and characterization of an alternating pyridine-pyridazine strand comprising thirteen heterocycles are described. Spontaneous folding into a helical secondary structure is based on a general molecular self-organization process enforced by the conformational information encoded within the primary structure of the molecular strand itself. Conformational control based on heterocyclic "helicity codons" illustrates a strategy for designing folding properties into synthetic oligomers (foldamers). Strong intermolecular interactions of the highly ordered lock-washer subunits of compound 3 results in hierarchical supramolecular self-assembly into protofibrils and fibrils. Compound 3 also forms mechanically stable two-dimensional Langmuir-Blodgett and cast thin films.

Heterocyclic Compounds↗
PubMed2002

Supramolecular polymers generated from heterocomplementary monomers linked through multiple hydrogen-bonding arrays--formation, characterization, and properties.

Supramolecular polymers are described that are derived from the association of two homoditopic heterocomplementary monomers through sextuple hydrogen-bonding arrays. They form fibers and a variety of different materials depending on the conditions. The strong affinity of the DAD-DAD (D=donor, A=acceptor) hydrogen-bonding sites for double-faced cyanuric acid type wedges drives the supramolecular polymeric assembly in apolar and chlorinated organic solvents. The marked influence of stoichiometry, as well as end-capping and cross-linking agents upon fiber formation is revealed in solution and by electron microscopy (EM). The results further contribute to the development of a supramolecular polymer chemistry that comprises reversible polymers formed through recognition-controlled noncovalent connections between the molecular components. Such materials are, by nature, dynamic and present adaptive character in view of their ability to respond to external stimuli.

Chemical Phenomena↗