Preparation, characterization, and antitumor properties of cis-PtCl₂ complexes linked to anthraquinones through position number 2

A new series of platinum-anthraquinone complexes of the type cis-PtLL′Cl₂ [where L is the monodentate AQ-NH-(CH₂)_n-NH₂ and L′ = NH₃ or LL′ is the bidentate ligand AQ-NH-(CH₂)_n. NH-(CH₂)₂-NH₂] in which the anthraquinone is linked to the diaminedichloroplatinum(II) moiety through position 2 was prepared and screened in vitro for antileukemic activity against P388 cells. All ligands were characterized by ¹H and ¹³C NMR spectroscopy and all complexes by ¹⁹⁵Pt NMR. The platinum complexes of anthraquinones which are modified in position 2 are significantly less potent than their analogs which are substituted in position 1. The activity of the complexes is either equal to or lower than the activity of the free ligands themselves. In the attempt to prepare AQ-NH-(CH₂)₄-NH-(CH₂)₂-NH₂, a new compound, 2-(N-pyrrolidine)anthraquinone, was obtained and its structure was determined by x-ray crystallography. It crystallized in the monoclinic system in the space group P2₁/c. The unit cell parameters are a = 9.595(1), b = 12.537(2), c = 11.461(1) A ̊, β = 94.14(2)°, V = 1375(1) A ̊³, and z = 4.