Ferrocene-substituted calix[4]pyrrole: a new electrochemical sensor for anions involving CH⋯anion hydrogen bonds

Syntheses of Calix[4]Pyrroles by Amberlyst-15 Catalyzed Cyclocondensations of Pyrrole with Selected Ketones

“…Calix [4]pyrroles are conformationally flexible macrocycles [6,7] of significant importance due to their binding under different conditions with anions [8], neutral substrates [9] and metal ions [10]. The complexation behavior of calix [4]pyrroles with anions and cations has been widely studied using fluorescent [11], colorimetric [12] and electrochemical signaling [13] devices. They find interesting applications as raw materials for transformation into novel calix [4]pyridines and calix [4]pyridinopyrroles [14], as new solid supports capable of separating anion mixtures [15], in optical recognition of organic vapors [16] and as biologically active species [17].…”

Anion Sensors

“…Gale, Sessler and coworkers have reported the synthesis of a calix [4]pyrrole macrocycle containing a ferrocene group 19 ( Fig. 19.4) [39]. NMR titrations in DMSO-d 6 /acetonitrile-d 3 mixtures showed that, upon addition of anions such as chloride, the ferrocene protons in the alpha position of the cyclopentadienyl ring shift downfield.…”

Modification of glassy carbon electrode by the electrochemical oxidation of 3‐aminophenylcalix[4]pyrrole in nonaqueous media

“…It has been reported that this type of hydrogenbonding interaction is even possible between ferrocene CH and anion coordinated with calixpyrrole ring. [15] The coordinated BF 4 − anion interacts with the proton of the peripheral amino phenyl grou and prevents the modification through amine nitrogen atoms. X-ray crystal analysis revealed that the anion complexes of calix [4]pyrrole adopt a conelike confirmation such that the four pyrrolic NH protons can hydrogen bond to anions, leaving pyrrolic β-carbon at the same side to bind to the carboxylic or alcoholic oxygen atoms.…”