(cis)-5,10,15,20-Tetrakis[2-(arylurea)phenyl]porphyrins: novel neutral ligands for remarkably selective and exceptionally strong chloride anion complexation in (CD3)2SO

Urea appended free-base porphyrins 2–4 bind strongly (K > 10 5 dm 3 mol - 1 ) to spherical Cl - in (CD 3 ) 2 SO and exhibit significant binding selectivity since they complex with Cl - to a much greater extent (10 3 –10 2 :1) than with the trigonal NO 3 - and tetrahedral H 2 PO 4 - anions.