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Schaefer C.,Institute for Complex Molecular Systems | Voets I.K.,Institute for Complex Molecular Systems | Palmans A.R.A.,Institute for Complex Molecular Systems | Meijer E.W.,Institute for Complex Molecular Systems | And 4 more authors.
ACS Macro Letters | Year: 2012

In a combined experimental and theoretical approach, we investigate the supramolecular polymerization of ionic discotic amphiphiles into nanorods of varying mean length, depending on the temperature and ionic strength of the buffered aqueous solution. Invoking a nucleated supramolecular polymerization model that explicitly deals with the effects of screened Coulomb interactions, we correlate the degree of cooperativity of the supramolecular polymerization with the ionic strength of the solution, as probed by means of circular dichroism spectroscopy. Experiment and theory show that electrostatic interactions between the amphiphiles in the rods make the polymerization less cooperative, implying that the larger the concentration of mobile ions in the solution the larger the cooperativity due to their screening effect. We furthermore extract quantitative information about the effective surface charge densities of the supramolecular nanorods in solution, a parameter that has been particularly difficult to determine experimentally in other related self-assembled systems. © 2012 American Chemical Society.

Bakker M.H.,Institute for Complex Molecular Systems | Lee C.C.,Novartis | Meijer E.W.,Institute for Complex Molecular Systems | Meijer E.W.,TU Eindhoven | And 3 more authors.
ACS Nano | Year: 2016

Supramolecular polymers are an emerging family of nanosized structures with potential use in materials chemistry and medicine. Surprisingly, application of supramolecular polymers in the field of drug delivery has received only limited attention. Here, we explore the potential of PEGylated 1,3,5-benzenetricarboxamide (BTA) supramolecular polymers for intracellular delivery. Exploiting the unique modular approach of supramolecular chemistry, we can coassemble neutral and cationic BTAs and control the overall properties of the polymer by simple monomer mixing. Moreover, this platform offers a versatile approach toward functionalization. The core can be efficiently loaded with a hydrophobic guest molecule, while the exterior can be electrostatically complexed with siRNA. It is demonstrated that both compounds can be delivered in living cells, and that they can be combined to enable a dual delivery strategy. These results show the advantages of employing a modular system and pave the way for application of supramolecular polymers in intracellular delivery. © 2016 American Chemical Society.

Zhang X.-Q.,TU Eindhoven | Van Santen R.A.,TU Eindhoven | Van Santen R.A.,Institute for Complex Molecular Systems | Jansen A.P.J.,TU Eindhoven
Physical Chemistry Chemical Physics | Year: 2012

We present a lattice-gas kinetic Monte Carlo model to investigate the formation of silicate oligomers, their aggregation and the subsequent gelation process. In the early oligomerization stage, the 3-rings are metastable, 5-rings and 6-rings are formed in very small quantities, 4-rings are abundant species, linear and branched species are transformed into more compact structures. Results reveal that the gelation proceeds from 4-ring containing species. A significant amount of 5-rings and 6-rings, sharing Si with 4-ring, form in the aging stage. These reveal the formation mechanism of silicate rings and clusters during zeolite synthesis. This journal is © 2012 the Owner Societies.

Van Der Graaff W.N.P.,TU Eindhoven | Li G.,TU Eindhoven | Mezari B.,TU Eindhoven | Pidko E.A.,TU Eindhoven | And 2 more authors.
ChemCatChem | Year: 2015

Sn-Beta zeolite was prepared by acid dealumination of Beta zeolite, followed by dehydration and impregnation with anhydrous SnCl4. The formation of extraframework Sn (EFSn) species was prevented by the removal of unreacted SnCl4 in a methanol washing step prior to calcination. The resulting Sn-Beta zeolites were characterized by X-ray diffraction, Ar physisorption, NMR, UV/Vis, and FTIR spectroscopy. These well-defined Lewis acid zeolites exhibit good catalytic activity and selectivity in the conversion of 1,3-dihydroxyacetone to methyl lactate. Their performance is similar to a reference Sn-Beta zeolite prepared by hydrothermal synthesis. Sn-BEA zeolites that contain EFSn species exhibit lower catalytic activity; the EFSn species also catalyze formation of byproducts. DFT calculations show that partially hydrolyzed framework Sn-OH species (open sites), rather than the tetrahedral framework Sn sites (closed sites), are the most likely candidate active sites for methyl lactate formation. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Smulders M.M.J.,Institute for Complex Molecular Systems | Filot I.A.W.,Institute for Complex Molecular Systems | Leenders J.M.A.,Institute for Complex Molecular Systems | Van Der Schoot P.,TU Eindhoven | And 3 more authors.
Journal of the American Chemical Society | Year: 2010

Here, we report on the strong amplification of chirality observed in supramolecular polymers consisting of benzene-1,3,5-tricarboxamide monomers and study the chiral amplification phenomena as a function of temperature. To quantify the two chiral amplification phenomena, i.e., the sergeants-and- soldiers principle and the majority-rules principle, we adapted the previously reported sergeants-and-soldiers model, which allowed us to describe both amplification phenomena in terms of two energy penalties: the helix reversal penalty and the mismatch penalty. The former was ascribed to the formation of intermolecular hydrogen bonds and was the larger of the two. The latter was related to steric interactions in the alkyl side chains due to the stereogenic center. With increasing temperature, the helix reversal penalty was little affected and remained rather constant, showing that the intermolecular hydrogen bonds remain intact and are directing the helicity in the stack. The mismatch penalty, however, was found to decrease when the temperature was increased, which resulted in opposite effects on the degree of chiral amplification when comparing the sergeants-and-soldiers and the majority-rules phenomena. While for the former a reduction in mismatch penalty resulted in a decrease in degree of chiral amplification, for the latter it resulted in a stronger chiral amplification effect. By combining the sergeants-and-soldiers and majority-rules phenomena in a diluted majority-rules experiment, we could further determine the effect of temperature on the degree of chiral amplification. Extending the experiments to different concentrations revealed that the relative temperature, i.e., the temperature relative to the critical temperature of elongation, controls the degree of chiral amplification. On the basis of these results, it was possible to generate a general "master curve" independent of concentration to describe the temperature-dependent majority-rules principle. As a result, unprecedented expressions of amplification of chirality are recorded. © 2010 American Chemical Society.

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