Syntheses, crystal structures, and metal ion complexation studies of noveldiaza-18-crown-6 ligands containing aromatic thiol-derived side arms

The Mannich aminomethylation reaction of aromatic thiols has been used to p roduce diaza-18-crown-6 ligands containing thiol-derived side arms. Thiophe nols were attached to the azacrown through N-CH2-S linkages even in the pre sence of hydroxy or acetamido groups. Heteroaromatic thiols containing N=C- SH (or NH-C=S) structural fragments were attached to diaza-18-crown-6 by N- CH2-N linkages with the thiol becoming a thione function. X-ray crystal str uctural analyses show the N-CH2-S and N-CH2-N linkages for some of the new macrocyclic compounds. Interactions of four of the new diaza-18-crown-6 lig ands with Na+, K+, Ba2+, Ag+, Zn2+, Cd2+, Ni2+, and Cu2+ were evaluated by calorimetric titration at 25 degrees in methanol. The results show that the se ligands form stable complexes with many of the metal ions studied.