Search results for "calixarene"

Unexpected Conformational Behaviour of a Diphosphate Derived from a Spherand-Type Calixarene

2005

The spherand-type calixarene 2a, which consists of three diphenol units linked by methylene bridges, was treated with phosphorus pentachloride and then with water. A C1-symmetrical conformation was found for the resulting bisphosphate 7 in the crystalline state by X-ray analysis, with an anti orientation of the phosphoryl groups. MM3 calculations lead to a nearly identical conformation for the most stable isomer (RRS-twist), while a slightly higher energy was found for an RRS-crown isomer with a syn orientation of the phosporyl groups. Surprisingly, all NMR studies (1H, 13C and 31P) of 7 are in agreement with a dynamic C2 symmetry in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Wein…

Near-Infrared-Responsive Choline-Calix[4]arene-Gold Nanostructures for Potential Photothermal Cancer Treatment

2022

The development of novel chemical approaches for the fabrication of gold nanostructures with localized surface plasmon resonance (LSPR) falling in the near-infrared (NIR) region is one challenging topic in nanomaterials science. Due to their optical and photothermal properties triggered by light excitation in the therapeutic window (λmax = 650-1300 nm), gold-based nanostructures are appealing candidates in anticancer nanomedicine. Here, we report a novel method to prepare water-dispersible gold nanostructures with NIR-LSPR (λmax = 600-1000 nm) properties. The gold nanostructures were achieved in a single step by an unconventional method using NADH as a reducing agent and an amphiphilic chol…

Recent Advances in Halogen Bonded Assemblies with Resorcin[4]arenes

2020

Resorcinarenes are cavity-containing compounds when in the crown conformation, from the calixarene family of concave compounds. These easy to synthesize macrocycles can be decorated at the upper rim through the eight hydroxyl groups and/or the 2-position of the aromatic ring. They are good synthons in supramolecular chemistry leading to appealing assemblies such as open-inclusion complexes, capsules and tubes through multiple weak interactions with various guests. Halogen bonding (XB) is a highly directional non-covalent interaction by an electron-deficient halogen atom as a donor that interacts with a Lewis base, the XB acceptor. This tutorial review provides an overview of recent advances…

Protected but Accessible: Oxygen Activation by a Calixarene-Stabilized Undecagold Cluster

2013

DFT computations show that calixarenes stabilize subnanometer Au11 clusters allowing access of small molecules like O2 to reactive metal sites in the core. Maximum of three dioxygen molecules can bind to the cluster, and they are activated to a superoxo O2(-) state. This study predicts that gold clusters could act as viable oxidation catalysts at ambient conditions based on similar principles as the metal centers in enzymes.

CCDC 1524101: Experimental Crystal Structure Determination

2017

UCUZOK : 6,12,18,24-tetramethoxy-2,8,14,20-tetranonyl-4,10,16,22-tetrahydroxycalix[4]arene propan-2-ol solvate Space Group: P-1, Cell: a 12.27090(10)Å b 13.96500(10)Å c 19.53620(10)Å, α 83.2880(1)° β 89.0250(1)° γ 84.9650(1)° Work published 2017 via Cambridge Crystallographic Data Centre.

CCDC 264161: Experimental Crystal Structure Determination

2017

WEJVOZ : New structure undergoing enhancement. Space Group: P21/c, Cell: a 18.5217(4)Å b 23.2973(6)Å c 21.1118(3)Å, α 90.00° β 96.591(1)° γ 90.00°. Work published 2017 via Cambridge Crystallographic Data Centre.

CCDC 750239: Experimental Crystal Structure Determination

2014

UDUXOI : 2,26,51,54-Tetraethyl-6,24,30,48-tetramethoxy-9,12,15,18,21,33,36,39,42,45-decaoxaheptacyclo[27.19.3.35,25.03,8.022,53.027,32.046,50]tetrapentaconta-1(48),3,5,7,22,24,27,29,31,46,49,52-dodecaene methanol solvate. Work published 2014 via Cambridge Crystallographic Data Centre.

SMART NANOSPONGE-BASED SYSTEMS FOR ADVANCED APPLICATIONS

2023

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…