π−π Stacking and magnetic coupling mechanism on a mononuclear Cu(II) complex

Synthesis, crystal structures, and magnetic properties of two supramolecular coordination complexes constructed by sulfonate groups

“…The χ M T decreases continuously with decreasing temperature and reaches a minimum of 0.151 cm 3 K mol À1 near 1.8 K. The 1/χ M versus T plot obeys the Curie-Weiss law with a Weiss constant of h = À4.91 K and a Curie constant C of 0.404 cm 3 K mol À1 . The negative h value is indicative of dominant antiferromagnetic interactions between Cu 2+ centers [13,19]. The χ M T value is 0.377 cm 3 K mol À1 at 300 K for 2, which is close to the spin only value of 0.375 cm 3 K mol À1 (g = 2.0) expected for a total spin S = 1/2.…”

“…In IR spectra of 1 (figure S2 in Supplementary material), peaks at 1609, 1483, and 1355 cm À1 can be assigned to vibrations of C-N and C-C of pyridine, which are lower energy than in 4-hydroxypyridone-3-sulfonic acid (1637, 1501, and 1370 cm À1 ), indicating coordination of N of pyridine [13][14][15]. Characteristic vibrations of ν as SO À 3 in 1 are 1263 and 1184 cm À1 , whereas the ν s ðSO À 3 Þ is at 1010 cm À1 , both different from that in 4-hydroxypyridone-3-sulfonic acid (ν as ðSO À 3 Þ at 1255, 1176 cm À1 and ν s ðSO À 3 Þ at 1018 cm À1 ), due to coordination of SO À 3 with Cu(II).…”

“…IR spectra of 2 (figure S3 in Supplementary material) show no strong peaks at 1634 or 1458 cm À1 , indicating that there may be no pyridine ring in 2 [13][14][15]. The peak at …”

Effects of the tetravanadate [V4O12]4− anion on the structural, magnetic, and biological properties of copper/phenanthroline complexes

“…Concerning the antiferromagnetic interaction in 3 , the spin-density extends over the N-containing rings of neighboring dmp ligands that participate in π – π stacking (Fig. S17c), so that the exchange interaction may proceed through such interaction as supported by other Cu(II)-based complexes [ 116 , 117 ]. Finally, the weak antiferromagnetic interaction in 4 can also be explained by the long Cu⋯Cl contacts occurring between adjacent complexes in view of the spin-density phase shared by both atoms (Fig.…”