Search results for "Cucurbituril"
showing 10 items of 15 documents
Materiali ibridi a base di nanotubi di allosite per la rimozione d’inquinanti
2017
L’allosite (HNT) è un interessante materiale argilloso allumino-silicato naturale, non tossico e biocompatibile, con la caratteristica forma tubolare cava dotata di parziale carica positiva interna e negativa esterna.Combinando le peculiarità di un composto organico con le proprietà di un materiale inorganico, è possibile ottenere sistemi ibridi organici–inorganici con interessanti proprietà e vasti campi di applicazione. Sono un esempio delle “nanospugne” capaci di adsorbire efficacemente potenziali inquinanti. In questo contesto sono stati preparati, dei materiali ibridi “spugna” costituiti da unità ciclodestriniche e allosite e ancora un sistema ibrido HNT-Cucurbit[8]uril. Il primo possi…
Application of the Generalized Molar-Ratio Method to the Determination of the Stoichiometry and Apparent Binding Constant of Nanoparticle-Organic Cap…
2015
A generalization of the molar-ratio method is applied to the determination of the stoichiometry and apparent binding constant of metal nanoparticle-organic capping complexes (MmLx) using voltammetric data for the oxygen reduction reaction (ORR) in air-saturated aqueous phosphate buffer solutions. The method is applied to the formation of binary nanohybrids consisting of gold nanoparticles (AuNPs) capped with a rigid spacer, cucurbit[7]uril (CB), termed AuNP@CB, as well as to the formation of their ternary complexes (MmLxBz) with methylene blue (MB), termed AuNP@CB@MB. The obtained stoichiometries correspond to binding of four Au surface atoms for each CB unit.
Chemistry inside molecular containers in the gas phase.
2013
Inner-phase chemical reactions of guest molecules encapsulated in a macromolecular cavity give fundamental insight into the relative stabilization of transition states by the surrounding walls of the host, thereby modelling the situation of substrates in enzymatic binding pockets. Although in solution several examples of inner-phase reactions are known, the use of cucurbiturils as macrocyclic hosts and bicyclic azoalkanes as guests has now enabled a systematic mass spectrometric investigation of inner-phase reactions in the gas phase, where typically the supply of thermal energy results in dissociation of the supramolecular host-guest assembly. The results reveal a sensitive interplay in wh…
Strong Emission Enhancement in pH-Responsive 2:2 Cucurbit[8]uril Complexes
2019
Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional con…
Breaking the Nd3+-sensitized upconversion nanoparticles myth about the need of onion-layered structures
2018
Up to now, most strategies to build efficient 800 nm-light responsive upconversion nanoparticles (UCNPs) have included onion-layered structures, in which Nd3+ is confined within the inorganic crystal structure of at least one layer. We report here an easy room-temperature modular preparation of core-shell UCNPs consisting of NaYF4:Yb,Er(Tm)/NaYF4 (UCCS) with Nd3+ anchored at the organic capping by using cucurbituril[7] (CB[7]) as an adhesive. Strikingly, excitation at 800 nm effectively triggers the upconversion emission of UCCS@CB[7]@Nd nanohybrids.
The Luminescence of CH3NH3PbBr3Perovskite Nanoparticles Crests the Summit and Their Photostability under Wet Conditions is Enhanced
2016
CH3 NH3 PbBr3 perovskite nanoparticles (PAD ) are prepared with a photoluminescence quantum yield of ≈100% in air atmosphere by using the quasi-spherical shaped 2-adamantylammonium bromide (ADBr) as the only capping ligand. The photostability under wet conditions of this kind of nanoparticles is enhanced by using cucurbit[7]uril-adamantylammonium (AD@CB) host-guest complexes as the capping ligand.
Initial Biological Assessment of Upconversion Nanohybrids
2021
Nanoparticles for medical use should be non-cytotoxic and free of bacterial contamination. Upconversion nanoparticles (UCNPs) coated with cucurbit[7]uril (CB[7]) made by combining UCNPs free of oleic acid, here termed bare UCNPs (UCn), and CB[7], i.e., UC@CB[7] nanohybrids, could be used as photoactive inorganic-organic hybrid scaffolds for biological applications. UCNPs, in general, are not considered to be highly toxic materials, but the release of fluorides and lanthanides upon their dissolution may cause cytotoxicity. To identify potential adverse effects of the nanoparticles, dehydrogenase activity of endothelial cells, exposed to various concentrations of the UCNPs, was determined. Da…
Nanocomposite based on Multi-Macrocyclic Receptors and Halloysite for Volatile Organic Compounds Capture
2015
Volatile organic compounds (VOCs) are chemicals released to the atmosphere by natural and anthropogenic sources. VOCs are hazardous air pollutants and promote formation of photochemical smog. Variety of chemicals released from pharmaceutical industry includes priority pollutants like benzene, toluene, and dichloromethane. The aim of this work was at designing, preparing and characterizing from the physico-chemical view-point a pseudo nano-sponge with low environmental impact for pollutant removal. As adsorbent material, a nanocomposite based on nanoclay and cucurbiturils, which are biocompatible materials, were investigated. Clay minerals (e.g. montmorillonite and kaolin) are important comp…
Enhanced catalytic electrochemical reduction of dissolved oxygen with ultracleancucurbituril[7]-capped gold nanoparticles
2014
Gold nanoparticles capped with cucurbituril[7] have been prepared in the absence of metallic cations and organic ligands. Remarkably, these nanohybrids encapsulate dissolved oxygen and are highly active in electrochemical reduction. The effect of the presence of sodium and ammonium salts on this catalysed process is also analysed.
Strong Emission Enhancement in pH‐Responsive 2:2 Cucurbit[8]uril Complexes
2019
Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional con…