2D dysprosium complex exhibiting slow magnetic relaxation originating from the strong Ising anisotropy of single Dy³⁺ ions has been reported.

The cocrystals were assembled with 1,4-diiodotetrafluorobenzene (1,4-DITFB) as the halogen bonding donor and the polycyclic aromatic hydrocarbons (PAH), biphenyl (Bp), naphthalene (Nap), phenanthrene (Phe), as the π-type halogen bonding acceptors, corresponding to cocrystals 3 (Bp-DITFB), 4 (Nap-DITFB) and 5 (Phe-DITFB), respectively. The single crystal X-ray diffraction analysis reveals that the two-dimensional layer in 3 or the one-dimensional chain structures in 4 and 5 are formed by C–I⋯π halogen bonds, and that the C–I⋯π bonding occurs in both above-the-carbon and above-the-bond models of DITFB to PAHs. Other intermolecular interactions in cocrystals such as C–F⋯F–C contacts, edge-to-edge type π–π stacking and C–H⋯I hydrogen bonding are also significant in maintaining the stability of supramolecular structures. The stoichiometry of all three cocrystals is 1 : 2 of PAH to DITFB. The PAHs with smaller conjugation systems and linear (not more than two benzene rings) or bent structures may be apt to form cocrystals with 1,4-DITFB by C–I⋯π halogen bonding. The cocrystals are well characterized by various spectroscopic methods. Additionally, the cocrystals 4 and 5, as expected, produce strong green and orange phosphorescence, respectively, due to strong spin-orbital coupling of iodine atoms. Phosphorescence of Phe in cocrystal 5 appears to be largely red-shifted compared with regular emission in solution or on general solid-supports. The phosphorescence decay of cocrystals 4 and 5 both obey a mono-exponential form with lifetimes of 0.067 ms and 1.449 ms, respectively.

Two supramolecular cocrystals, 1, pyrene/1,4-diiodotetrafluorobenzene (1,4-DITFB), and 2, pyrene/1,2-diiodotetrafluorobenzene (1,2-DITFB), have been prepared and characterized using X-ray diffraction analysis and multiple spectroscopic methods. Several intermolecular interactions such as C–I⋯I–C, C–I⋯π, π–π and C–H⋯F were observed in cocrystal 1 and/or 2, in which DITFB molecules act simultaneously as an isolator to prevent the pyrene molecule from aggregating and also as a heavy atom effect agent to induce phosphorescence emission from pyrene. The spectral results demonstrate that the two cocrystals both display strong phosphorescence at room temperature with decay rates of 1.7 × 10³ s⁻¹ and 0.22 × 10³ s⁻¹, respectively. The differences in the phosphorescence behavior between 1 and 2 are relevant to the local molecular environment created by 1,4- or 1,2-DITFB in cocrystals.

A novel ferromagnetic 1D dysprosium chain was synthesized. It exhibits slow magnetic relaxation, originating from the single-ion behaviour of Dy³⁺ as indicated by dc and ac magnetic data of both diluted and un-diluted samples.

A novel 1D dysprosium complex was synthesized by employing a pyridine-N-oxide ligand. It exhibits slow magnetic relaxation with an energy barrier of 227 K under zero dc field.