Study on the interaction of anions with A2B cobalt corroles in non-aqueous medium

Abstract

A series of five cobalt corrole complexes Co[(p-NO2Ph)2RCor](py)2 where R is functionalized with different aromatic aldehydes at meso positions, was examined in acetonitrile solvent. Three of the five complexes changed color to green in 10[Formula: see text] M acetonitrile solution. Their potential to sense anions was investigated using the colorimetric and spectroscopic approach in 14 different tetrabutyl ammonium salts of F[Formula: see text], CN[Formula: see text], CH3COO[Formula: see text], NO[Formula: see text], AsO[Formula: see text], AsO[Formula: see text], Cl[Formula: see text], Br[Formula: see text], I[Formula: see text], ClO[Formula: see text], H2PO[Formula: see text], S[Formula: see text], HS[Formula: see text]and PF[Formula: see text]. Co-1, Co-2 and Co-4 shows selectivity towards F[Formula: see text], CN[Formula: see text]and CH3COO[Formula: see text] by their changing of color from green or reddish-brown to dark reddish-brown. The complexes exclusively bind these three anions at their axial positions. The binding constant determination gives the number of binding species (n) >1 at less than one equivalent concentration of anions in the acetonitrile solution of the complex. A band appeared at around 735 nm, on the other hand, suggests that a bis(CN)-derivative of corrole complex could form under >1 equivalent anionic conditions. The limit of detection for the Co-4 was superior than Co-1 and Co-2, which were 0.0068 [Formula: see text]M for CN[Formula: see text], 0.0082 [Formula: see text]M for F[Formula: see text]and 0.0177 [Formula: see text]M for CH3COO[Formula: see text] ion. Although the complexes detect all three anions at less than 1 equivalent of the anion addition, the Co-1 and Co-2 are more selective towards CH3COO[Formula: see text]ion, whereas Co-4 selectively detects CN[Formula: see text]anion at larger equivalents of these anions.