• IUPAC definition Calixarene: Originally macrocyclic compounds capable of assuming a basket (or 'calix') shaped conformation. (wikipedia.org)
  • The 4 hydroxyl groups interact by hydrogen bonding and stabilize the cone conformation. (wikipedia.org)
  • Alternatively placing a bulky substituent on the upper rim also locks a conformation. (wikipedia.org)
  • The formation of the calixarene metal complexes is considered in two steps, (a) in a distortion from the equilibrium conformation of the free calixarenes and (b) subsequent complexation. (uni-bielefeld.de)
  • The most stable conformation for the coordination products of these cations with the calix[4]arene with 12 OH groups is a slightly flattened 'crown' that is derived by maximum hydrogen bonding of the OH-groups and the most effective cation-pi interactions. (uni-bielefeld.de)
  • With hydrophobic cavities that can hold smaller molecules or ions, calixarenes belong to the class of cavitands known in host-guest chemistry. (wikipedia.org)
  • Special cases are complexes of Li+ and Na+ which in most instances prefer the coordination on the oxygen atoms of the upper rim of the calixarene cavities and thus form 'boat'-like structures. (uni-bielefeld.de)
  • A substituent in the meso position Rb is added to the name with a prefix C- as in C-methylcalix[6]arene The word calixarene is derived from the Greek calix or chalice because this type of molecule resembles a vase (or cup) and from the word arene that refers to the aromatic building block. (wikipedia.org)
  • In calix[4]arene 4 up-down conformations exist: cone (point group C2v,C4v), partial cone Cs, 1,2 alternate C2h and 1,3 alternate D2d. (wikipedia.org)
  • He introduced the name "calixarene": from "calix", the Greek name for a chalice, and "arene" for the presence of aryl groups in the cyclic array. (wikipedia.org)
  • Calixarenes represent excellent building blocks for the design of solid-state architectures, in particular calix-4-arenes crystallize easily and the introduction of a wide range of director functions is relatively simple. (usf.edu)
  • Careful examination of the crystal packing of a series of calix-4-arene derivatives systematically modified with various alkyl chain lengths at the lower rim and selected functional groups at the upper rim will be considered in the broader perspective of crystal engineering strategies and development of novel materials. (usf.edu)
  • A variety of conformations for three model calix[4]arenes with 8 or 12 OH groups have been investigated by calculations at density functional (RI-BP86) and RI-MP2 level of approximation. (uni-bielefeld.de)
  • Rozhenko AB, Schoeller W, Letzel M, Decker B, Agena C, Mattay J. Conformational features of calix[4]arenes with alkali metal cations: A quantum chemical investigation with density functional theory. (uni-bielefeld.de)
  • In a second step, addition of a Lewis base generates a tetracoordinate adduct, which serves as an activating group, enabling functionalization of one of the boron-bound oxygen atoms by a second electrophile. (acs.org)
  • The other classes of β-lactam antibiotics, namely carbapenems and monobactams, were discovered more recently [ 7 ] [ 8 ] , in an effort to identify new members of this broad group of molecules. (encyclopedia.pub)
  • Calixarenes are characterised by a wide upper rim and a narrow lower rim and a central annulus. (wikipedia.org)
  • With phenol as a starting material the 4 hydroxyl groups are intrannular on the lower rim. (wikipedia.org)
  • For example, amphiphilic and pseudo-amphiphilic calixarenes may be synthesized by selective functionalization at either face of the skeleton and a second functionality may then be introduced at the opposite face. (usf.edu)
  • In these processes, a tricoordinate boronic ester initially serves as a protective group for a sugar-derived 1,2- or 1,3-diol motif, permitting functionalization of free OH groups. (acs.org)
  • In a resorcin[4]arene 8 hydroxyl groups are placed extraannular on the upper ring. (wikipedia.org)
  • Conformations can be locked in place with proper substituents replacing the hydroxyl groups which increase the rotational barrier. (wikipedia.org)
  • In addition, the third coupling was achieved with the substrate bearing a free hydroxyl group. (acs.org)
  • Calixarenes are sparingly soluble as parent compounds and have high melting points. (wikipedia.org)
  • In addition, regular exercise increases the functional activity of mitochondrial respiratory chain (MRC) complexes and upregulates the expression levels of MRC complexes. (bvsalud.org)
  • The calixarenes form stable complexes with the alkali metal cations of lithium up to caesium. (uni-bielefeld.de)
  • Pd(II) extraction experiments were conducted using single-metal Pd(II) solutions, simulated mixed palladium group metal (PGM) solutions, and acid-leached automotive catalyst residue solutions. (nature.com)
  • Calixarenes exist in different chemical conformations because rotation around the methylene bridge is not difficult. (wikipedia.org)
  • In calix[4]arene 4 up-down conformations exist: cone (point group C2v,C4v), partial cone Cs, 1,2 alternate C2h and 1,3 alternate D2d. (wikipedia.org)
  • The calixarene based on p-tert-butyl phenol is also a cone. (wikipedia.org)
  • A detailed density functional theory study has also been carried out to understand the energetic relationships among cone conformers, intramolecular hydrogen-bonding patterns, and DMSO encapsulation. (ufg.br)
  • Calixarenes are characterised by a wide upper rim and a narrow lower rim and a central annulus. (wikipedia.org)
  • With phenol as a starting material the 4 hydroxyl groups are intrannular on the lower rim. (wikipedia.org)