Search results for "calixarenes"
showing 10 items of 50 documents
Low-generation dendrimers with a calixarene core and based on a chiral C2-symmetric pyrrolidine as iminosugar mimics
2012
The preparation of low-generation dendrimers based on a simple calix[4]arene scaffold by insertion of the iminosugar-analogue C2-symmetric 3,4-dihydroxypyrrolidine is described. This methodology allows a rapid incorporation of a considerable number of iminosugar-like moieties in a reduced volume and in a well-defined geometry. The inclusion of alkali-metal ions (sodium and potassium) in the polar cavity defined by the acetamide moieties at the lower rim of the calixarene was demonstrated, which allows also the rigidification of the dendrimer structure and the iminosugar presentation in the clusters. The combination of the supramolecular properties of calixarenes with the advantage of a dend…
The Structural Diversity of Benzofuran Resorcinarene Leads to Enhanced Fluorescence
2014
An unexpected and previously unknown resorcinarene mono-crown with a fused benzofuran moiety in its macrocyclic core was obtained as a byproduct from a bridging reaction of tetramethoxy resorcinarene with tetraethylene glycol ditosylate. The formation of the fused benzofuran moiety in the resorcinarene macrocycle resulted in a unique rigid and puckered boat conformation, as shown by XRD studies in the solid state. Modification of the macrocycle was also observed to affect the photophysical properties in solution by enhancing the fluorescence brightness compared with a conventional resorcinarene macrocycle. The fluorescent properties enabled unique detection of structural features, that is, …
Docetaxel-Loaded Nanoparticles Assembled from β-Cyclodextrin/Calixarene Giant Surfactants: Physicochemical Properties and Cytotoxic Effect in Prostat…
2017
Giant amphiphiles encompassing a hydrophilic β-cyclodextrin (βCD) component and a hydrophobic calix[4]arene (CA4) module undergo self-assembly in aqueous media to afford core-shell nanospheres or nanocapsules, depending on the nanoprecipitation protocol, with high docetaxel (DTX) loading capacity. The blank and loaded nanoparticles have been fully characterized by dynamic light scattering (DLS), ζ-potential measurements and cryo-transmission electron microscopy (cryo-TEM). The data are compatible with the distribution of the drug between the nanoparticle core and the shell, where it is probably anchored by inclusion of the DTX aromatic moieties in βCD cavities. Indeed, the release kinetics …
Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials
2018
New calixarene-based nanosponges (CaNSs), i.e., hyper-reticulated polymers constituted by calixarene monomer units joined by means of bis(1,2,3-trialzolyl)alkyl linkers, were synthesized, characterized and subjected to preliminary tests to assess their supramolecular absorption abilities towards a set of suitable organic guests, selected as pollutant models. The synthesis was accomplished by means of a CuAAC reaction between a tetrakis(propargyloxy)calix[4]arene and an alkyl diazide. The formation of the polymeric network was assessed by means of FTIR and 13C{1H} CP-MAS solid-state NMR techniques, whereas morphological characterization was provided by SEM microghaphy. The materials were pro…
Badanie właściwości inkluzyjnych p-tert-butylokaliksarenów metodą inwersyjnej chromatografii gazowej
2007
Metodą QSRR scharakteryzowano właściwości inkluzyjne p-tert-butylokaliksarenów o 4, 6 i 8 merach w cyklu oraz ich octanów, wykorzystując do tego celu inwersyjną chromatografię gazową. W badaniach zastosowano przy tym dwa szeregi homologiczne solutów - alkohole alifatyczne oraz benzen i jego homologi. Stwierdzono, że zdolności inkluzyjne w znacznym stopniu zależą od wymiarów luki molekularnej cyklomeru. Zamiana w kaliksarenach grup wodorotlenowych na octanowe nie wywiera natomiast istotnego wpływu na możliwości tworzenia kompleksów typu gość-gospodarz. Wyniki uzyskane metodą QSRR potwierdzono wyznaczonymi wartościami indeksów Kovátsa.
Badanie metodą inwersyjnej chromatografii gazowej wpływu wielkości podstawnika na właściwości inkluzyjne kaliksarenów
2009
Badano wpływ wielkości alifatycznego podstawnika na zdolności inkluzyjne kaliksarenów {kaliks[4]arenu(K4), p-izopropylokaliks[4]arenu (IPK4) i p-tert-butylokaliks[4]arenu (TBK4)}. Oceny wpływu dokonywano za pomocą metody QSRR przy użyciu inwersyjnej chromatografii gazowej. W charakterze solutów użyto szeregu alifatycznych alkoholi, homologów benzenu i homologów pirydyny. Na podstawie indeksów retencji Kovatsa i wykresów zależności właściwej objętości retencji od temperatury wrzenia [Vg=f(Tw)] stwierdzono, że tylko podstawione kaliksareny wykazują właściwości inkluzyjne w stosunku do niższych alkoholi.
Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges
2019
Two mixtures of polyaminoazides were synthesized by a nucleophilic displacement strategy providing no separation of the components. The mixtures were adequately characterized by means of combined HR-ESIMS, FTIR and NMR techniques and, despite their complexity, they were successfully used to accomplish the subsequent preparation of pH-sensitive calixarene hyper-reticulated nanosponge materials. The desired responsivity to pH variations of the nanosponges obtained was verified by means of absorption tests on a set of organic pollutant model molecules.
Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: New multivalent galectin-3 ligands
2014
Four novel calix[4]arene-based glycoclusters were synthesized by conjugating the saccharide units to the macrocyclic scaffold using the CuAAC reaction and using long and hydrophilic ethylene glycol spacers. Initially, two galactosylcalix[4]arenes were prepared starting from saccharide units and calixarene cores which differ in the relative dispositions of the alkyne and azido groups. Once the most convenient synthetic pathway was selected, two further lactosylcalix[4]arenes were obtained, one in the cone, the other one in the 1,3-alternate structure. Preliminary studies of the interactions of these novel glycocalixarenes with galectin-3 were carried out by using a lectin-functionalized chip…
Cyclodextrin–calixarene co-polymers as a new class of nanosponges
2014
Hyper-reticulated co-polymers jointly formed by cyclodextrin and calixarene units, which can be considered as a new class of nanosponges, were easily obtained by means of a click chemistry approach. In particular, we succeeded in preparing our materials by exploiting the copper-catalyzed 1,3-dipolar cycloaddition (CuAAC) reaction between heptakis-(6-deoxy)-(6-azido)-beta-cyclodextrin and (5,11,17,23-tetra-tert-butyl)-(25,26,27,28-tetra-propargyloxy)-calix-[4]-arene, mixed in different proportions. These materials were fully characterized by means of combined FT-IR, thermogravimetric, C-13 {H-1} CP-MAS NMR and nitrogen adsorption/desorption techniques. In particular, C-13 {H-1} CP-MAS spectr…
Supramolecular Organocatalysis in Water Mediated by Macrocyclic Compounds
2018
In the last decades many efforts have been devoted to design supramolecular organocatalysts able to work in water as the reaction medium. The use of water as solvent provides promising benefits with respect to environmental impact. In this context, macrocyclic compounds played a role of primary importance thanks to their ease of synthesis and their molecular recognition abilities toward the reactants. The aim of this review is to give an overview of the recent advances in the field of supramolecular organocatalysis in water, focusing the attention on calixarene and cyclodextrins derivatives. Calixarenes and cyclodextrins, thanks to their hydrophobic cavities, are able to host selectively th…