Functionalized calix[4]pyrroles

Abstract

Abstract:The synthesis and properties of a number of functionalized calix[4]pyrroles are described. To date, two generalized preparative approaches have been pursued. The first involves modifying the basic pyrrole-plus-ketone synthesis of calix[4]pyrrole by using modified precursors or by co-condensing more than one ketone with pyrrole. The second approach relies on the reaction of a pre-formed calix[4]pyrrole with an electrophile. In both cases, the resulting species can be subject to further manipulation. In this way a range of structures, including ones bearing ancillary recognition subunits, electro-or photochemical reporter groups, and/or water solubilizing substituents may be obtained. Solid supports bearing calix[4]pyrroles may also be produced in this way.

Tri‐ and Pentacalix[4]pyrroles: Synthesis, Characterization and Their Use in the Extraction of Halide Salts

“…[7] Moreover, chromatographic separation systems have been generated by attaching receptors to an appropriate stationary phase. [8] These and other practical considerations have led to a spectacular growth within the anion-recognition field. However, the weak nature of most anion-receptor interactions, particularly in the case of neutral-anion-receptor systems that reflect the relatively low-charge density of most anions, [9] makes the design of selective and effective receptors an on-going challenge.…”

“…Thus, while a number of research groups have designed elegant anion receptors, many of which have proven to be quite effective, there still remains a need for simple and easy-to-make anion-binding systems. In this context, calix [4]pyrroles, which are macrocyclic compounds containing four pyrrole units connected to each other through sp 3 -hybridized carbon atoms, have emerged as molecules of particular interest, [8] because the core structure can be accessed in one synthetic step and a large number of modifications are readily conceivable. To date, simple meso-alkyl-substituted, halogenated, [10] C-rim modified, [11] photoactive and chromophore-modified, [5] strapped, [12] ditopic, [13] expanded, [14] Nconfused, [15] siloxane-functionalized, [16] and polyfunctional [17] calixpyrrole derivatives have been reported.…”

Expanded porphyrins. Synthetic materials with potential medical utility

“…One approach that appears attractive involves the use of modi®ed calixpyrroles bearing¯uorescent reporter groups (e.g. 12) [37]. Another, is to generate pyrrolic entities containing built-in chromophores.…”

Deciphering Noncovalent Interactions Accompanying 7,7,8,8‐Tetracyanoquinodimethane Encapsulation within Biphene[n]arenes: Nucleus‐Independent Chemical Shifts Approach

“…[14] The majority of macrocyclic arenes containing monobenzene or substituted benzenes, such as calixarenes from phenols, [15] resorcinarenes from resorcinol, [16] cyclotriveratrylenes from veratrole, [17] and pillararenes from hydroquinone, [18] have been synthesized and characterized. To this end, modified arene hosts comprised of heterocyclic units, namely, pyrroles, [19] pyridines, [20] and imidazolium [21] heterocycles, have also been reported.…”