Structural, Spectroscopic, and Photochemical Investigation of an Octahedral NO-Releasing {RuNO}⁷ Species

Abstract

[Ru(Me3[9]aneN3)(bpy)(NO)](BF4)2 ([1](BF4)2) was explored by single-crystal X-ray diffractometry, leading to the first crystal structure of an octahedral {RuNO}(7) complex. The metal resides on the center of a distorted octahedron, with dN-O and ∠Ru-N-O at 1.177(3) Å and 141.6(2)°, respectively. [1](BF4)2 can be stored indefinitely under argon. Solutions of [1](2+) show no signs of decomposition when protected from air and light. The electron paramagnetic resonance X-band spectrum at 85 K in vitrified acetonitrile (MeCN) shows signals consistent with an S = (1)/2 spin state, better described as Ru(II)NO(•) (g = [2.030, 1.993, 1.880] and A = [11.0, 30.4, 3.9]/10(-4) cm(-1)). In water, the {RuNO}(7) species reacts with O2 in a 1:4 stoichiometry. The reaction is first-order in both reactants with k = (1.9 ± 0.2) M(-1) s(-1) at 25 °C (ΔH(⧧) = 11.5 ± 0.3 kJ mol(-1); ΔS(⧧) = -189 ± 1 J K(-1) mol(-1)). Solutions of [1](2+) evolve NO when irradiated a 365 nm with ϕNO = 0.024 and 0.090 mol einstein(-1) in H2O and MeCN, respectively.

Coordination Chemistry of Nitric Oxide and Biological Signaling

“…Plot of ln k O2 vs E NO+ / NO for the reactions of O 2 with different complexes: [1]: [Ru(Me 3 [9]aneN 3 )(bpy) (NO)] 2+ ;[97] [2]: [Fe II (CN) 5 (NO)] 3− ;[97] [3]: [Ru II (NH 3 ) 5 (NO)] 2+ ,[98] and[4]: Ru II (bpy)(tpm)(NO)] 2+ [99]. Extracted from reference[97].…”

A New Member of the Growing Family of Interconvertible {RuNO}6,7,8 Species. Redox and Acid‐Base Characterization of [Ru((CH2py)2Me[9]aneN3)(NO)]n+

“…In a series of publications preceding the present one, [16][17][18][19] we have reported detailed studies based on octahedral [Ru-(Me 3 [9]aneN 3 )(L 2 )(NO)] n + (L 2 = 2,2'-bipyridine, 4,4'-dimethoxy-2,2'-bipyridine and 2,2'-bipyrimidine) and cis-[Ru(L py )(NO)] n + (L py = 1-(pyridine-2-ylmethyl)-1,4,8,11-tetraazacyclotetradecane) complexes. In all these cases, we have been able to explore the consecutive one-electron reduction processes which convert the {RuNO} 6 species into the {RuNO} 7 and {RuNO} 8 ones, while addressing the spectroscopic characterization of the different oxidation states.…”

The design of TACN-based molecular systems for different supramolecular functions

“…Fig. 73a), whose solutions proved to be sensitive to a 365 nm irradiation source leading to NO release [177]. This property makes this complex appealing for photodynamic therapy applications, as it is well established that NO could cause cellular apoptosis.…”

“…The radiolabelling of L73 with 90 Y and 177 Lu was found to be very efficient and the complexes were stable in serum for at least 14 days. A derivative of L73 conjugated to an antibody was also synthesised for RIT applications and the biodistribution of 90 Y and 177 Lu complexes was evaluated in vivo on nude mice bearing ZR-75-1 human breast cancer [170]. The magnetic data show a temperature dependence of the magnetic susceptibility, with χT values going from 33.3 to 28.5 cm 3 mol -1 K -1 on cooling, suggesting the presence of intracomplex ferromagnetic interactions.…”

“…In vivo PET imaging, biodistribution and blocking studies were performed in 4T1 murine A derivative of NOTA used for radioimmunotherapy (RIT) is the so-called NETA ({4-[2-(biscarboxymethyl-amino)-ethyl]-7-carboxymethyl- [1,4,7]triazonan-1-yl}-acetic acid). NETA is an octadentate ligand containing the NOTA skeleton and a flexible acyclic tridentate pendant arm and it is a promising chelator for of α-and β-emitters, including 90 Y, 177 Lu, 212 Bi, 213 Bi and 212 Pb. A derivative of NETA called 3p-C-NETA (L73) was synthesised using an unprecedented synthetic method based on the region-specific ring opening of the aziridinium ion [169].…”