Three pyridine-based, macrocyclic, oxygen-, nitrogen-, and sulfur-containing ligands, 15-aza-6-oxa-3,9-dithiabicyclo[9.3.1]pentadeca-1(15),11,13-triene, 18-aza-6,9-dioxa-3,12-dithiabicyclo[12.3.1]octadeca-1(18),14,16-triene, and 21-aza-6,9,12-trioxa-3,15-dithiabicyclo[15.3.1]heneicosa-1(21),17,19-triene, are reported. The molecular and crystal structure of the 15-aza-6-oxa-3,9-dithiabicyclo[9.3.1]pentadeca-1(15),11,13-triene was solved by X-ray diffraction methods; the space group is monoclinc, P2(1)/c, with a = 9.048 (1) angstrom, b = 15.315 (2) angstrom, c = 9.565 (2) angstrom, beta = 116.52 (1)-degrees, V = 1186 (2) angstrom3, Z = 4, d(calcd) = 1.352 g.cm-3, and mu = 4.05 cm-1. Its molecular structure is compared with that found by molecular mechanics calculations using the MM2 program. Complexes with Cu(II), Ni(II), and Co(II) metal ions are also reported. The molecular structure of the (15-aza-6-oxa-3,9-dithiabicyclo[9.3.1]pentadeca-1(15),11,13-triene)dichlorocopper(II) complex is described; the space group is monoclinc, P2(1)/n, with a = 7.381 (1) angstrom, b = 13.916 (3) angstrom, c = 14.336 (6) angstrom, beta = 100.10 (2)-degrees, V = 1449 (2) angstrom 3, Z = 4, d(calcd) = 1.720 g.cm-3, and mu = 21.5 cm-1. Neutral mobile carrier based liquid membrane electrodes have been prepared by using 15-aza-6-oxa-3,9-dithiabicyclo[9.3.1]pentadeca-1(15),11,13-triene as the sensor material, and their potentiometric response toward Cu(II), Ni(II), and Co(II) is also reported.