Search results for "Supramolecular"
showing 10 items of 830 documents
Inverse Thermogelation of Aqueous Triblock Copolymer Solutions into Macroporous Shear-Thinning 3D Printable Inks
2020
Amphiphilic block copolymers that undergo (reversible) physical gelation in aqueous media are of great interest in ditIerent areas including drug delivery, tissue engineering, regenerative medicine, and biofabrication. We investigated a small library of ABA-type triblock copolymers comprising poly(2-methyl-2-oxazoline) as the hydrophilic shell A and different aromatic poly(2-oxazoline)s and poly(2-oxazine)s cores B in an aqueous solution at different concentrations and temperatures. Interestingly, aqueous solutions of poly(2-methyl-2-oxazoline)-block-poly(2-phenyl-2-oxazine)-block-poly(2-methyl-2-oxazoline) (PMeOx-b-PPheOzi-b-PMeOx) undergo inverse thermogelation below a critical temperatur…
Coordination compounds for molecular electronics: Synthesis, characterization and electronic transport properties of copper rotaxanes and molecular c…
2014
Esta tesis se centra en el estudio de compuestos de coordinación de interés en el campo de la electrónica molecular. Este campo tiene como objetivo la utilización de unidades moleculares como componentes activos en circuitos electrónicos. Los dispositivos unimoleculares presentan cualidades únicas, inherentes a la nanoescala, que no poseen equivalencia en los componentes convencionales, actualmente basados en el silicio. Además, la síntesis de moléculas dispone de un altísimo grado de control sobre el tamaño y estructura final que permite la fabricación ‘a medida’ de estos componentes. Entre otros compuestos, los complejos metálicos despiertan un especial interés debido sus ricas propiedade…
Diseño, síntesis y caracterización de sistemas híbridos. aplicaciones médicas y medioambientales.
2016
El desarrollo que ha experimentado la Química Supramolecular en el campo del reconocimiento ha permitido a los investigadores, dar un paso adelante en el diseño y la síntesis de arquitecturas supramoleculares bien definidas, con un tamaño nanométrico a partir de la autoorganización de los receptores. En este sentido, el descubrimiento de nuevos materiales, procesos y el desarrollo de nuevas técnicas experimentales ha permitido el desarrollo de nuevos nanosistemas con aplicaciones muy innovativas en comparación con las especies por separado. Entre los posibles materiales que se pueden emplear, las nanopartículas presentan un gran interés debido a sus propiedades ópticas, magnéticas, electrón…
Química de coordinación catiónica y aniónica de nuevos poliazareceptores politópicos
2013
La química supramolecular es uno de los campos de la Química que más se ha desarrollado en los últimos 50 años. La importancia de la química supramolecular se ha potenciado por su carácter multidisciplinar, ya que se puede considerar como un triple punto de encuentro entre la Química, la Biología y la Física. La primera definición de química supramolecular se atribuye al Profesor Jean-Marie Lehn que la describió como “la Química más allá de la molécula” en referencia a las entidades organizadas que resultan de la asociación de dos o más especies químicas unidas mediante fuerzas no covalentes. En el presente trabajo nos hemos centrado en la síntesis de receptores con estructuras macropolicíc…
Exploring the self-assembly of resorcinarenes : from molecular level interactions to mesoscopic structures
2012
Sulfate-Templated 2D Anion-Layered Supramolecular Self-Assemblies
2019
Summary Using solution and solid-state analyses, we demonstrate that the tripodal N-methylated(1,3,5-benzene-tricarboxamide)-tris(phenylurea) BTA ligands, possessing urea functionalities in the meta position, are able to form extended self-assembly 2D networks via hydrogen bonding templated by sulfate (SO42–). The divergence of the urea binding sites confers a propeller-like conformation to the ligands and is key to formation of the self-assemblies. Studies in solution and in the solid state as well as scanning electron microscopy (SEM) on the self-assembly properties of the ligands showed that the convergence also leads to the formation of hierarchical structures, including porous films an…
A new series of π-extended tetrathiafulvalene derivatives incorporating fused furanodithiino and thienodithiino units: a joint experimental and theor…
2004
A new family of tetrathiafulvalenes has been prepared. The materials exhibit complex redox behaviour related to the electronic influence of the 1,4-dithiin moieties embedded within the framework of the molecules. The X-ray crystal structure of compound 4 reveals an unusual non-planar conformation of the heterocyclic compound, with the TTF fragment adopting a boat conformation. Theoretical calculations, performed at the DFT level (B3P86/6-31G*), confirm the boatlike structure (C2v symmetry) as the most stable conformation for this family of tetrathiafulvalenes. Upon oxidation, electrons are extracted from the whole molecule and the radical cations and dications remain highly distorted from p…
Mass spectrometric study of oligourea macrocycles and their anion binding behavior
2009
Two series, one of tris-urea macrocycles and another of hexakis-urea macrocycles, are examined by (tandem) Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry with respect to their fragmentation patterns and anion binding properties. All macrocycles are based on two different building blocks, one of which is a very rigid xanthene unit and the other one is a more flexible diphenyl ether. The composition and the sequence of these units thus determine their flexibility. During the fragmentation of deprotonated oligourea macrocycles in the gas phase, one urea N-CO bond is cleaved followed by a scrambling reaction within the macrocycle structure. Consequently, fragments are obser…
Encapsulation of Xenon by a Self-Assembled Fe4L6 Metallosupramolecular Cage
2015
We report (129)Xe NMR experiments showing that a Fe4L6 metallosupramolecular cage can encapsulate xenon in water with a binding constant of 16 M(-1). The observations pave the way for exploiting metallosupramolecular cages as economical means to extract rare gases as well as (129)Xe NMR-based bio-, pH, and temperature sensors. Xe in the Fe4L6 cage has an unusual chemical shift downfield from free Xe in water. The exchange rate between the encapsulated and free Xe was determined to be about 10 Hz, potentially allowing signal amplification via chemical exchange saturation transfer. Computational treatment showed that dynamical effects of Xe motion as well as relativistic effects have signific…
High‐Zirconium‐Content Nano‐Sized Bimodal Mesoporous Silicas
2006
Silica-based nanoparticulated bimodal mesoporous materials with high Zr content (43 ≥ Si/Zr ≥ 4) have been synthesized by a one-pot surfactant-assisted procedure from a hydroalcoholic medium using a cationic surfactant (CTMABr = cetyltrimethylammonium bromide) as structure-directing agent, and starting from molecular atrane complexes of Zr and Si as hydrolytic inorganic precursors. This preparative technique allows optimization of the dispersion of the Zr guest species in the silica walls. The bimodal mesoporous nature of the final high surface area nano-sized materials is confirmed by XRD, TEM, and N2 adsorption–desorption isotherms. The small intraparticle mesopore system (with pore sizes…