title: Molecular structure, solution chemistry and biological properties of the novel [ImH][trans-IrCl(4)(Im)(DMSO)], (I) and of the orange form of [(DMSO)(2)H][trans-IrCl(4)(DMSO)(2)], (II), complexes.
abstract: The new iridium(III) complex, imidazolium[trans(DMSO,imidazole)tetrachloroiridate(III)], (I) (DMSO=dimethyl sulfoxide), and the orange form of [(DMSO)(2)H][trans(DMSO)(2)tetrachloroiridate(III)], (II) have been prepared and characterized, both in the solid state and in solution, by X-ray diffraction and by various physicochemical techniques. Single crystal X-ray diffraction studies point out that complex (II) is isomorphous to the ruthenium(III) analogue, [(DMSO)(2)H][trans-RuCl(4)(DMSO)(2)], (III). Crystallographic data are the following: a=16.028(2) A, b=24.699(3) A, c=8.262(1) A, in space group Pbca (Z=8) for (imidazolium)[trans(DMSO,imidazole)tetrachloroiridate(III)], (I); and a=9.189(2) A, b=16.511(4) A, c=14.028(3) A, beta=100.82(2) degrees in space group P2/n (Z=4) for [(DMSO)(2)H][trans(DMSO)(2)tetrachloroiridate(III)], (II). Visible absorption spectra show that both complexes are stable for several days, at pH 7.4, at room temperature. No significant chloride hydrolysis is observed, even at high temperature (70 degrees C), over 24 h. The extreme stability of these iridium(III) complexes within a physiological buffer was further assessed by (1)H NMR; in addition, cyclic voltammetry measurements evidenced a high stability of the oxidation state +3. Preliminary biological studies show that both complexes do not bind appreciably bovine serum albumin nor inhibit significantly the proliferation of representative human tumor cell lines, suggesting that hydrolysis of coordinated chlorides is a crucial feature for the biological properties and the antitumor activity of the parent ruthenium(III) complexes.
authors.affiliation: Department of Chemistry, University of Florence, Sesto Fiorentino, Firenze, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Messori
authors.forename: Giordana
authors.initials: G
authors.lastname: Marcon
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Orioli
authors.forename: Marco
authors.initials: M
authors.lastname: Fontani
authors.forename: Piero
authors.initials: P
authors.lastname: Zanello
authors.forename: Alberta
authors.initials: A
authors.lastname: Bergamo
authors.forename: Gianni
authors.initials: G
authors.lastname: Sava
authors.forename: Pasquale
authors.initials: P
authors.lastname: Mura
mesh_terms: D018360:Crystallography, X-Ray; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D007495:Iridium / Q000737:chemistry* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D014407:Tumor Cells, Cultured
chemical_list: D007093:Imidazoles; D009942:Organometallic Compounds; D012710:Serum Albumin, Bovine; D007495:Iridium