Search results for "nanosponge"

Nanosponge-C3N4 composites as photocatalysts for selective partial alcohol oxidation in aqueous suspension

2023

A set of four composite materials was prepared, consisting of a nanosponge matrix based on beta-cyclodextrin in which carbon nitride was dispersed. The materials were characterized by the presence of diverse cross-linker units joining the cyclodextrin moieties, in order to vary the absorption/release abilities of the matrix. The composites were characterized and used as photocatalysts in aqueous medium under UV, visible and natural solar irradiation for the photodegradation of 4-nitrophenol, and for the selective partial oxidation of 5-hydroxymethylfurfural and veratryl alcohol to the corresponding aldehydes. The nanosponge-C3N4 composites showed higher activity than the pristine semiconduc…

Reduced graphene oxide/silver nanoparticles/β-cyclodextrin nanosponges composites with improved photocatalytic activity

2023

Significant activity improvement was achieved by associating graphene oxide-silver composite photocatalysts with cyclodextrin-based nanosponge materials, due to the synergistic effect provided by the supramolecular host abilities of the nanosponge. Three photocatalysts were prepared, fully characterized (FT-IR, ss-NMR, Raman, XRD, SEM, EDX, AFM, ICP, TGA, potentiometric titration), and tested for the oxidative photodegradation of some dyes and phenols, chosen as model organic pollutants. Compared to the unsupported photocatalyst, the nanosponge-based materials showed enhanced performances (being able to carry out the degradation even of dyes which do not react in the presence of the unsuppo…

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…

Pre- and post-modification of mixed cyclodextrin-calixarene co-polymers: A route towards tunability

2017

Various pre-modified and post-modified cyclodextrin-calixarene hyper-reticulated co-polymers were synthesized, fully characterized by different techniques (FT-IR, 13C{1H} CP-MAS and LGFS solid-state NMR, thermogravimetry, porosimetry), and tested to assess their absorption abilities as nanosponges. The construction of the polymer network was accomplished exploiting the well-known CuAAC reaction between two different heptakis-6-azido-β-cyclodextrins and two different propargyloxy-calix[4]arenes. Post-modification was aimed to achieve the presence of ionizable (acidic or basic) groups on the polymer framework. Sequestration tests towards two model pollutant molecules surprisingly showed that …

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…

Scopolamine Derivatives as Potential Pharmaceuticals with Calixarene-CyclodextrineNanosponges as Drug Carriers

2017

Tropane alkaloids are molecules with a strong biological activity, which are mainly produced by the members offamily Solanaceae, but also found inother plant families (Convolvulaceae, Brasicaceae, Erythroxylaceae andEuphorbiaceae).1 More than 20 active pharmaceutical substances containingthetropane moiety have been industrially produced and applied as mydriatics, antiemetics, antispasmodics, anesthetics and bronchodilators.Nearly all of them are based on the Scopolamine structure.2 In recent years, several researchers aimed their work to the use of supramolecular systems for the inclusion of organic species, such as complex systems based on cyclodextrines or calixarenes.3They have attracted…