Resorcin arenes

Quantum yields (Yb111) or partial quantum yields (Nd111) for 1 1 complexes of LnIn chlorides with calix[4]resorcin-arenes and calix[4]arenes measured upon ligand excitation (290 nm) at room temperature... 

The higher energy of the triplet states in calixarenes 39a-f (fig. 37), 20600-23 500 cm , allows sizeable sensitization of Eu and Tb° luminescence. Compared with calix[4]resorcin-arenes, better quantum yields are also obtained for the Nd and Yb 1 1 complexes (table 7), 0.06-0.24%, and 0.09-0.61%, respectively. However, the solvent is not the same, dmf as compared to ethanol, which may explain the difference. As for the calix[4]resorcinarene complexes, the speciation in solution has not been established, but in this case, the 1 1 complexes have been isolated and gave satisfactory elemental analyses (Korovin and Rusakova, 2001 Shevchuk et al., 1998a). The best quantum yields are obtained with H239f which bears two phenylamide chromophores on the narrower rim and these substituents are directly coordinated onto the lanthanide ion, which understandably increases the efficiency of the energy transfer process. 

Reports of conformational supramolecular isomers of organic materials include that of the compound 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile, 5, which has at least six polymorphs. The main difference in the six phases is the variation in the torsion angle between the thiophene and the o-nitroaniline moieties. Another example involves the two components C-methylcalix[4]resorcin-arene (6) and 4,4 -bipyridine (bipy), which can form three supramolecular isomers (7) in the presence of different... 

Covalent and noncovalent combination of porphyrins as well as calix[4]arenes, resorcin[4]arenes including macroheterocyclic fragments, and cyclodextrins by construction of supramolecular artificial receptors 98EJ02689. 

Capsules are instantly formed by simple addition of two equivalents of Pd(dppp)(OTf)2 (dppp = l,3-bis(diphenylphosphino)propane) to acetone, CH2C12 or CHC13 solutions of resorcin [4]arene derivatives having four pyridine units as pendent groups, see Figure 64.637... 

The placement of four pyridyl groups on the upper rim of the resorcin[4]arene cavitands was followed by the addition of Pd(II) ions to generate a monomeric molecular receptor with hydrophobic binding sites <00TL3113>. The treatment of 2,4,6-rm[(4-pydrinyl)methyl-sulfanyl]-l,3,5-triazene (tpst) with silver to form a single-stranded one-dimensional coordination polymer, [Ag7(tpst)(C104)2(N03)5(dmf)2] , which contains nanotubes... 

Fig. 9.2 (a) X-ray crystal structure of 1 and (b) the snub cube, one of the 13 Archimedean solids. The square faces of the snub cube correspond to the resorcin[4]arenes the eight shaded triangles that adjoin three squares correspond to the water molecules of 1. 

The discovery that members of the resorcin[4]arene family self-assemble to form 1, owing to its classification as an Archimedean solid, prompted us to examine the topologies of related spherical hosts with a view to understanding their structures on the basis of symmetry. In addition to providing grounds for classification, we anticipated that such an approach would allow us to identify similarities at the structural level, which, at the chemical level, may not seem obvious and may be used to design large, spherical host assemblies similar to 1. 

We have recently demonstrated the ability of six resorcin[4]arenes and eight water molecules to assemble in apolar media to form a spherical molecular assembly which conforms to a snub cube (Fig. 9.3). [10] The shell consists of 24 asymmetric units - each resorcin[4]arene lies on a four-fold rotation axis and each H2O molecule on a three-fold axis - in which the vertices of the square faces of the polyhedron correspond to the corners of the resorcin[4]arenes and the centroids of the eight triangles that adjoin three squares correspond to the water molecules. The assembly, which exhibits an external diameter of 2.4 nm, possesses an internal volume of about 1.4 A3 and is held together by 60 O-H O hydrogen bonds. 

Methylene-bridged resorcin[4]arenes or cavitands, of the general structure shown in Scheme 8, are suitable as templates for the organization of peptide structure because of their rigidity, enforced cavities and synthetic availability.132 59 ... 

Scheme 8 Methylene-Bridged Resorcin[4]arenes Allow for the Attachment of, for Example, Peptides at the Rim Positions (R1) and Propylphosphate at the Pendant Groups (X1) 32 ...

Parent resorcin[4]arenes also show Cs selectivity in extraction from alkaline media (pH 12), for example, into benzene.24 With long alkyl chains appended to the bridging carbon atom, separation by flotation is possible. 

Calixarenes modified with a reporter site are equally competent chemosen-sors for the detection of a variety of analytes according to Scheme 6, especially when the analyte is cationic. The tt-cavity of a tetraanionic resorcin[4]arene readily binds cationic guests, a feature that Inouye et al. have exploited in the development of an acetylcholine chemosensor [358], The fluorescence from a pyrene-modified N-alkylpyridinium is strongly quenched upon its association with the tetraphenolate form of resorcin[4]arene (24). This quenching is consis-... 

MacGillivray, L.R. and Atwood, J.L. (2000) Cavity-containing materials based upon resorcin[4]arenes by discovery and design, J. Solid State Chem. 152, 199-210. 

Photochemical host-guest systems on the basis of photoswitchable macrocycles have also been investigated most recently in a number of publications. Schafer et al.23 and Anselmetti et al.24 modified a bifunctional resorcin[4]arene with two anthracene units and proved its switching function in photochemical induction and heating cycles. Moreover, they modified the lower rim of the resorcin[4]arene with four 10-(decylthio)decyl linkers for an oriented surface immobilization on gold via molecular self-assembly (Fig. 15.7). The affinity modulation of this optical switch was... 

Figure 15.7 Resorcin[4]arene photoswitch for self-assembly (a) and pictograms visualizing the diluted self-assembled monolayer of this photoswitch for single-molecule affinity studies by AFM (b).23 (Reprinted with permission from C. Schafer et al., J. Am. Chem. Soc. 2007,129, 1488-1489. Copyright 2007 American Chemical Society.)...

Different asymmetric residues with a different number of stereocenters attached with the same spacer to the resorcin[4]arene part showed an important influence on the encapsulated guest, even though the overall number of stereocenters changes drastically from 88 for 14-14 to only 8 for 12 12. These complementary experiments are undoubtedly proof of principle that magnetic desymmetrization of closed space can be performed by placing a chiral object outside the immediate environment. 

Supramolecular self-assembly can be as simple as acetic acid dimerization through mutually complementary hydrogen bonds or as complex as supramolecule formation from multiple components as demonstrated by numerous examples of resorcin[4]arene and calix[4]arene capsules. One of the more interesting directions to have been taken has been the design and synthesis of self-complementary... 

Besides these covalently constructed cage-type receptors a number of self-assembled capsules with hydrogen bond donors protruding to the inside have also been described. An early example was reported by Atwood et al. This system makes use of the well known properties of resorcin[4]arene 30a and pyrogallol[4]arene 30b to form hexameric spherical capsules in the solid state and, in the case of 30b, also in solution. 

Molecular Capsules Derived from Resorcin[4] arenes by Metal-Coordination... 

Keywords Cavitand Metal coordination Resorcin[4]arene Self-assembly Supramolecular chemistry Terpyridine ligand... 

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