Thiocarbonyl-bound metallonitrosyl complexes with visible-light induced DNA cleavage and promising vasodilation activity

Ruthenium-nitrosyl complexes as NO-releasing molecules, potential anticancer drugs, and photoswitches based on linkage isomerism

“…The most common synthetic routes to ruthenium nitrosyl complexes include: (a) the use of specific starting materials, which already contain the ruthenium nitrosyl moiety, via a variety of substitution reactions (NO 2 by Cl, 27 NH 3 , 28,29 pyridines, 29–33 pyrazine; 34 NO 3 by H 2 O, F; 35 OH by F; 22,36,37 Cl by pyridines, 38–40 tetradentate Schiff bases, 41,42 tetradentate 2-hydroxybenzamidobenzene derivatives, 43 bis-phosphine monoxide ligands; 44 H 2 O by Cl, 45 SO 4 ; 46 NH 3 by Cl 46 ) or metathesis reactions of Na + to Ba 2+ , 29 Ba 2+ to NH 4 + , 29 Cl − to ClO 4 − , 47 PF 6 − , 48 in solution and in the solid state; 45,46 (b) conversion of the coordinated nitro ligand into nitrosyl in acidic media (HCl, TFA, HFP 6 , HNO 3 ) reported for ruthenium triammine complex, 45 as well as for compounds with pyridine, bipyridine, terpyridine, phenanthroline, triazine, and indazole ligands (see references in Table 1); (c) direct reaction of ruthenium pyridine, bipyridine, terpyridine, porphyrin, corrole species (see Table 1) or ruthenium azole complexes 49 with NO via substitution reactions of labile monodentate ligands, e.g. , Cl, 50–54 H 2 O, 55,56 DMSO, 57 etc . As a source of nitric oxide, NO gas was used.…”

“…As a source of nitric oxide, NO gas was used. 52–54,57 This gas can also be produced by reactions of sodium nitrite with HBF 4 or H 2 SO 4 , 51,55 and copper with HNO 3 . 50 NOBF 4 was used to introduce the second NO ligand into the coordination sphere of ruthenium.…”

“…cis -[Ru(bpy) 2 (NO)X] n + (ref. 51) also showed a higher susceptibility to OH − attack and conversion to nitrite form, an thus requiring a lower pH to stabilize the nitrosyl complex. The complex [Ru(NO)(tpy)(NH·NH q )] 3+ was found to be a vasodilator in in vitro experiments with rat aorta rings precontracted by norepinephrine and phenylephrine that could act as reducing agents.…”

“…174 More recently, vasodilation activity through NO generation was confirmed for cis -[Ru(phen) 2 (NO)X] 3+ (phen = phenanthroline, X = thiourea or thiobenzamide), and along with the stabilization of nitrosyl- over the nitro-form of the complex at physiological pH, such compounds show potential for pharmacological applications that deserves further biological studies. 51…”

Recent advances in photorelease complexes for therapeutic applications

“…A lower quantum yield of NO˙ release was noted when the long-wavelength light was employed. The two complexes RU15a and RU15b , again studied by the group of Lopes, 51 used the phenanthroline chelate and a thiocarbonyl subunit. As well as studying the nitric oxide release process further work studied their DNA cleaving properties in the presence and absence of blue light.…”