Search results for "nanosponges"

PROPERTIES AND APPLICATIONS OF POLYAMINOCYCLODEXTRIN DERIVATIVES

Nel presente lavoro sono state prese in esame le potenziali applicazioni delle poliamminociclodestrine. In particolare, diversi derivati poliamminociclodestrinici (amCD) sono stati ottenuti utilizzando un approccio sintetico diretto, tramite reazione di sostituzione nucleofila tra la heptakis-(6-deossi)-(6-bromo)-βCD (BrβCD) e poliammine lineari. Una volta effettuata l’opportuna caratterizzazione NMR, ESI-MS e potenziometrica, sono state investigate diverse possibili utilizzazioni di tali materiali. Anzitutto, sono state valutate le capacità di dare complessi di inclusione host-guest con diversi derivati organici sia delle amCD libere che di materiali costituiti da nanospugne a base di amCD…

Evaluation of adsorption ability of Cyclodextrin-Calixarene Nanosponges towards Pb2+ ion in aqueous solution

2021

Abstract Different cyclodextrin-calixarene nanosponges (CyCaNSs) have been characterized by means of FFC-NMR relaxometry, and used as sorbents to remove Pb2+ ions from aqueous solutions. Considering that the removal treatments may involve polluted waters with different characteristics, the adsorption experiments were performed on solutions without and with the addition of background salts, under different operational conditions. The adsorption abilities and affinities of the nanosponges towards Pb2+ ions were investigated by measuring the metal ion concentration by means of Inductively Coupled Plasma Emission Spectroscopy (ICP-OES) and Differential Pulse Anodic Stripping Voltammetry (DP-ASV…

APPLICATION OF FFC-NMR TECHNIQUES FOR THE STUDY OF THE FEATURES OF NANOSPONGES

Fast-Field-Cycling (FFC) NMR relaxometry is a versatile and powerful tool for studying the microscopic dynamics of molecular systems, provided that a suitable analysis of the longitudinal relaxation kinetics and the relevant NMRD (i.e. longitudinal relaxation rate R1 vs. Larmor frequency νL) dispersion curves is performed. In particular, FFC-NMR can afford valuable information on the texture properties (average pore size, specific surface and specific pore volume) of porous materials, once they have been saturated with water. Thus, it appears a technique of choice for assessing the otherwise elusive texture properties of nanosponges (NSs). These hyper-crosslinked polymers, obtained by retic…

Nanosponge-C3N4 composites with improved photocatalytic activity for selective partial alcohol oxidation in aqueous suspension

2022

Composites of C3N4 with nanosponges based on β-cyclodextrins containing a 5% w/w of C3N4 were synthesised, physicochemicaly characterised and tested as heterogeneous photocatalysts for the degradation of 4-nitrophenol and for the partial oxidation of 5-hydroxymethyl-2-furfural and veratryl alcohol. The results outline a synergistic effect in terms of conversion and selectivity. The association of the nanosponges with the C3N4 enhances the photocatalytic activity of the semiconductor, possibly due to the local concentration effect occurring on the photocatalyst surface that would involve a concentration into the nanosponge matrix ca. 500 times larger than in the solution bulk. Composites of …

Heuristic Algorithm for the Analysis of Fast Field Cycling (FFC) NMR Dispersion Curves

2021

Evaluation of nuclear magnetic relaxation dispersion (NMRD) curves obtained by the fast field cycling nuclear magnetic resonance (FFC-NMR) relaxometry technique is a valuable tool for analyzing the microscopic dynamics of condensed matter systems. However, quantitative data analysis involves several conceptual and practical issues. Moving forward from previous literature approaches, we propose a new analysis method, relying on the elaboration of the inverse integral transform of the NMRD curve. Our approach results in a true heuristic method, able to unambiguously individuate the dynamic domains in the system, thereby avoiding the possible introduction of any element of discretion. The anal…

Water Dynamics at the Solid-Liquid Interface to Unveil the Textural Features of Synthetic Nanosponges.

2020

A Fast-Field-Cycling NMR investigation was carried out on a set of polyurethane cyclodextrin nanosponges, in order to gain information on their textural properties, which have been proven to be quite difficult to assess by means of ordinary porosimetric techniques. Experiments were performed on both dry and wet samples, in order to evaluate the behavior of the “non-exchangeable” C-bound 1H nuclei, as well as the one of the mobile protons belonging to the skeletal hydroxyl groups and the water molecules. The results acquired for the wet samples accounted for the molecular mobility of water molecules within the channels of the nanosponge network, leading back to the possible pore size distrib…

FFC-NMR techniques for assessing the texture features of nanosponges

2021

Nanosponges (NSs), i.e. hyper cross linked polymeric materials obtained by reticulating cyclodextrin units with suitable linker units, constitute an emerging class of functional materials, due to their easy synthesis and chemical modification, and to their tunable absorption and controlled release abilities as well. NSs are supposed to possess a thick network of nanochannels in their highly disordered structure. However, their textural features (average pore size, specific surface and specific pore volume) are quite difficult to estimate, and classical evaluation methodologies (N2 absorption isotherms analyzed by BET or BJH methods, or dye absorption isotherms1) have afforded questionable r…

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…

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.

Chemical and pharmaceutical evaluation of the relationship between triazole linkers and pore size on cyclodextrin–calixarene nanosponges used as carr…

2016

Mixed cyclodextrin–calixarene nanosponges were used to prepare some composites with the well known polyphenolic bioactive compounds quercetin and silibinin. The composites were characterized by means of different techniques (UV-vis, FT-IR, microcalorimetry, thermogravimetry), in order to assess their loading and thermal stability. The kinetics of release of the bioactive molecules into aqueous solution were studied at two different pH values (1.0, 6.4), which mimic typical physiological conditions. Finally the possible antiproliferative effects in vitro were assayed towards three triple negative breast cancer cell lines (SUM 149, SUM 159 and MDA-MB-23). Our results point out the role assume…