Colorimetric anion sensing by porphyrin-based anion receptors

Porphyrin derivatives 1-4 with H-bond donors and/or color-reporting chromophoric unit were synthesized and studied as anion-binding receptors. 1 and 2 exhibited binding selectivity in the order of AcO->H(2)PO(4)much greater than Cl-, Br-, I- in DMSO-d(6). Color change tests with several different anions for colorimetric anion sensors (3 and 4) resulted in selectivities for F-, AcO- and H2PO4- in organic solution. While 1 and 2 exhibited good selectivities for AcO- and H2PO4-, 3 and 4 showed a dramatic color change for F- due to increased interaction with a nitrophenylazo phenolic OH group. (C) 2001 Elsevier Science Ltd. All rights reserved.