Host-guest complexes calixarenes

These molecules are significant in the field of research devoted to host—guest complexation. Synthetic routes to a number of calixarenes have been developed (11). 

Only few investigations have been published on the gas-phase ion chemistry of host-guest complexes of calixarenes. With the advent of ESI mass spectrometry, especially when combined with ion-trap and FT-ICR mass spectrometry, this field has started to be developed. Binding selectivities of alkali metal ions to cahxarene-based crown ethers and open-chain ethers have been studied , the inclusion of neutral guests into the protonated resorcarene-based cavitand hosts by gas-phase ion-molecule reactions with amines have been studied and the formation of capsules from various calixarene tetraether derivatives and alkylammonium ions as ionic guests (notably enabling their detection by mass spectrometry) have been described recently . ... 

Molecular modeling of calixarenes and their host-guest complexes, F. C. J. M. van Veggel, in Calixarenes in Action, L. Mandolini and R. Ungaro, Eds., Imperial College Press, London, 2000. 

Harrowfield, J.M. Richmond. W.R. Sobolev. A. Inclusion of quaternary ammonium compounds by calixarenes. J. Inch Phenoin. Mol. Recognit. Chem. 1994. 19. 257. Lippmann, T. Wilde. H. Pink. M. Schaefer. A. Hesse. M. Mann. G. Host-guest complexes between resorcinol-derived cal ix [4] arenas and alkyl ammonium ions. Angew. Chem. 1993, 105, 1258-1260. ... 

HOST-GUEST COMPLEXES Calixarenes and Related Molecules Calix[8]arenes, 1, n=8... 

Van Veggel, F.C.J.M. Molecular Modeling of Calixarenes and Their Host-Guest Complexes. In Calixarenes in Action Mandolini, L.. Ungaro, R.. Eds. Imperial College Press Singapore. 2000 11-36. 

Fig. 3 Self-assembly of three calix[4]arenas (la) functionalired with two melamine groups and six complementary barbiturate building blocks (2) into a (la)326 superstructure. Mixing in of another calixarene building block functionalized with Zn-porphyrin units (lb) generates a small DCL of four superstructures. Addition of a tripyridine guest (3) shifts the equilibrium in favor of the host-guest complex (lb)326 32. (Adapted from Refs. [9] and [10].)...

The calixarenes are important molecular receptors and play a major role in host-guest supramolecular chemistry [162, 163, 163a], Their conic shape favors host-guest complexation of various hydrophobic molecules and the functionalized rim enables interaction with polar molecules. Modifieation of calixarenes by organometallic moieties can be achieved ... 

All these examples illustrate the great versatility of calixarenes as supports for a variety of other functions able to participate in host-guest complexing and cation and anion sensing. 

Calix[4]resorcinarenes, a subclass of calixarenes, are large cyclic tetramers that have found applications as macrocyclic receptors, host molecules, host-guest complexes, and so on (Botta et al, 2005 Martinez et al., 2000 Leyton et al., 2005 Yonetake et al, 2001). It shonld be noted that the synthesis of calix[4]resorcinarenes was first reported in the late nineteenth century by Bayer based on the concentrated sulfuric acid-catalyzed cyclocondensation of benzaldehyde and resorcinol (Bayer, 1872). These cyclic compounds were synthesized by TSA (Scheme 3.8) (Karami etal.,2012f). 

In these solid inclusion componnds, the association of host and guest components is strictly a solid state phenomenon, and the examples covered in this chapter focns almost entirely on solid inclnsion componnds of this type. However, it is relevant to note that there is also another class of inclnsion compound in which the host is a molecnle containing an appropriate cavity or binding site that can inclnde gnest molecules. Such molecular host-guest complexes generally exist as associated entities both in the solntion state and in the crystalline state, and thns the incln-sion phenomenon is not exclusively a property of the solid state. Examples of host molecules of this type are crown ethers, cyclodextrins, cryptands, and calixarenes. 

Inclusion of cationic molecules by hosts in organic solvents is also observed with other host molecules, such as crown ethers and calixarenes. Cat-ion/n and coordination interactions are the main driving forces in these complexes. However, the formation of host-guest complexes with neutral... 

Depending on the relative surface coverage of subphthalocyanine 7 and Ceo on Ag(lll), periodic intermixed monolayers consisting of ID chains of 1-nm width or 2D hexagonal patterns were formed [ 127). Also imder potential control weU-defined host-guest complexes are formed. Empty calixarenes and C6o-caIixarene complexes can be visuahzed at the electrolyte Au(lll) interface. hi this case, the Ceo-calixarene complex is preformed before formation of the monolayer [128]. 

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