Structures of substituted di-aryl-1,3,4-oxadiazole derivatives: 2,5-bis(pyridyl)- and 2,5-bis(aminophenyl)-substitution

PdII and PtII complexes with a thio-aza macrocycle ligand containing an intercalating fragment: Structural and antitumor activity studies

Two new Pt^II and Pd^II complexes of formula [LMCl₂] (M=Pt, Pd) were synthesized and characterized both in solution and solid state. They were obtained using the thio-aza macrocycle 9,18-dimethyl-12,17dithia-9,18,27,28-tetraaaza-29-oxatetracyclo[24.2.1.0^2,7.0^20,25]enneicosa-2,4,6,20,22,24,26,28¹-octaene (L) containing the 2,5-diphenyl [1, 3, 4]oxadiazole as intercalating fragment. M^II is coordinated in cis-position by the two S atoms of L. The two crystal structures of [LPtCl₂] and [LPdCl₂] complexes showed that the M^II ion is located outside the macrocyclic cavity. The square planar coordination sphere is fulfilled by two chloride anions in a cisplatin-like arrangement with the chloride leaving groups exposed to the environment. The biological activity of both [LPtCl₂] and [LPdCl₂], monitored towards a leukemic cellular model (U937), is coherent with their ability to interfere, at different levels, with the DNA structure.

4-[5-(4-Benzoyloxyphenyl)-1,2,4-oxadiazol-3-yl]phenyl benzoate

In the title compound, C₂₈H₁₈N₂O₅, the dihedral angle between the terminal benzoate rings is 20.67 (12)°. The central oxadiazole ring is almost coplanar with its two benzene ring substituents, making dihedral angles of 4.80 (16) and 5.82 (16)°. In the crystal, pairs of C—H⋯O hydrogen bonds form inversion dimers with R₂²(40) ring motifs. The structure also features C—H⋯O, C—H⋯π and π–π inter­actions [centroid–centroid separation = 3.695 (4) Å].