Novel trans-disubstituted hexaaza-macrocyclic ligands containing pyridine head units: Synthesis, disubstitution and colorimetric properties

Abstract A trans -N,N′-methylated hexaazamacrocycle precursor L 3 , derived from the hexadentate polyamine macrocycle L (Py2[18]aneN6), was synthesized for the first time. The crystal structures of the intermediates L 1 · 8H 2 O and L 2 I 2 · H 2 O showing two trans quaternary nitrogen atoms have also been determined by single-crystal X-ray crystallography. By the alkylation of the trans secondary amines present in L 3 , two novel macrocyclic molecular probes 1 and 2 linked to two nitrophenylurea and two nitrophenylthiourea groups, respectively, are reported. Crystals of 1 ·2CDCl 3 suitable for single-crystal X-ray diffraction analysis were also obtained. The coordination ability of compounds 1 and 2 toward hydrated nitrate salts of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) was studied. Their responses toward different anions (fluoride (F − ), chloride (Cl − ), bromide (Br − ), iodide (I − ), hydroxide (OH − ), acetate (AcO − ), cyanide (CN − ), dihydrogen phosphate (H 2 PO 4 − ), nitrate (NO 3 − ) and perchlorate (ClO 4 − )) in DMSO solution were evaluated by UV–vis absorption spectroscopy. The immobilization of probe 1 in cellulose supported systems to evaluate its efficiency in the fast recognition of different anions (F − , AcO − , CN − , H 2 PO 4 − ) in aqueous phase was also described.