Chromogenic calix arenes

Chawla and Srinivas have synthesized new chromogenic calix[8]arenes (Figure 97) which exhibit observable color changes (with Al up to 100 nm) with mono- and diamines, the shift being larger for diamines [125]. Diamines were also detected in the presence of an excess of monoamines. 

Figure 97 A chromogenic calix[8]arene for the detection of amines [125]...

Benounis, M., Jaffrezic-Renault, N., Halouani, H., Lamartine, R. and Dumazet-Bonnamour, I. (2006) Detection of heavy metals by an optical fiber sensor with a sensitive cladding including a new chromogenic calix[4]arene molecule. Materials Science and Engineering C, 26, 364-8. 

Thus, the characteristic potentiometric selectivity of calix[6]arene hexaester 29 for primary amine guests can be reasonably interpreted on the basis of the structural factors relevant to the nonpolar moieties of guests. Such a mode of discrimination can also be achieved by a calix[6]arene hexaester with short alkyl chains [28 (R = H)]. In addition, the selectivity was found to be essentially the same in the presence or absence of lipophilic anionic site HFPB added in the membrane (Table 3). Potentiometric discrimination of protonated amines by host 28 (R = H, Bu ) as well as of aldehydes (as the protonated hydrazones generated in situ) by hosts 26 (R = Bu ) and 28 (R = H) was also reported. Recently, quantitative estimation of optical selectivities for alkali metal ions or protonated amines were made with liquid membranes containing chromogenic derivatives of calixarenes. ... 

The doubly functionalized calix[4]arene 9, bearing two chiral arms , was prepared recently [48]. This neutral system proved not only to be a good receptor for a-phenylglycine anions, it was also found to display good enantioselectivity towards the L-isomer fCa(L)//< l(D) = 4.76. It was thus proposed by the authors, that this presumably preorganized receptor could function as a chromogenic sensor for nonracemic a-phenylglycine anions. 

Chang K-C, Su I-H, Lee G-H, Chung W-S (2007) Triazole- and Azo-coupled Calix[4]arene as a highly sensitive chromogenic sensor for Ca and Pb ions. Tetrahedron Lett 48 7274-7278... 

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