Photoactivatable CO‐Releasing Properties of {Ru(CO)₂}‐Core Pyridylbenzimidazole Complexes and Reactivity towards Lysozyme

Abstract

The photoinduced CO-releasing properties of [RuL Py (CO) 2 Cl 2 ] (1), [Ru(L Py2Bz -ĸ 2 N 1 ,N 2 )(CO) 2 Cl 2 ] (2), and [Ru(L Py2Bz-Et -ĸ 3 N 1 ,N 2 ,N 3 )(CO) 2 (Cl)]·PF 6 (3) [L Py = 2-(2-pyridyl)benzimidazole, L Py2Bz = 2,6-bis(benzimidazole-2′-yl)pyridine, and L Py2Bz-Et = 2,6-bis(1-ethyl-benzimidazol-2′-yl)pyridine] in both DMSO and reduced myoglobin solution are reported. Complexes 1 and 2 release CO upon illumination at 365 nm. The bidentate chelation mode of L Py2Bz in 2 is changed into a meridional tridentate mode upon the ethylation of the benzimidazolic NH groups, 3. The extension of the conjugation system and the shift of the MLCT band into the visible region in 3

RuII–Carbonyl photoCORMs with N,N‐Benzimidazole Bidentate Ligands: Spectroscopic, Lysozyme Binding Affinity, and Biological Activity Evaluation

“…Experimentally, the aerated DMSO solutions of 2 and 3 are stable. Their illumination profiles (Figure b) resemble that of 1 and the previously published Ru II photoCORMs , . A clear isosbestic point is observed at 382 nm that may be taken as an evidence of CO release.…”

“…It was difficult to assign the ν(Ru–Cl) mode(s) consistent with the cis ‐ or trans ‐(Cl, Cl) isomer from the far‐IR spectra of 2 and 3 . However, the value of Δν(CO) [ν s (CO) – ν as (CO)] could be used to estimate which isomer was obtained . The values of Δν(CO) of 2 and 3 are in the range of 50–72 cm –1 , which compare well with the presence of the two chlorido ligands in the trans positions.…”

“…For example, changing one CO in [Ru(qmtpm)(CO) 2 Cl]ClO 4 {qmtpm = 2‐quinoline‐ N ‐(2′‐methylthiophenyl)methylenimine} with PPh 3 gives rise to a CORM capable of releasing CO with low‐power (15 mW/cm 2 ) visible light. Recently, [RuCl(L‐ĸ 3 N 1 ,N 2 ,N 3 )(CO) 2 ]PF 6 {where L = 2,6‐bis(1‐ethyl‐benzimidazol‐2′‐yl)pyridine} and [RuCl 2 (BZM) (CO) 2 ] (where BZM = Bromazepam, an antianxiety drug) have been introduced; they have excellent CO‐releasing properties upon illumination with blue light at 468 nm. The applications of Ru II –carbonyl complexes have been extended, to include them being used as effective photo‐ and electrocatalysts, especially in the reduction of CO 2 …”

Pyridylbenzimidazole based Re(i)(CO)3 complexes: antimicrobial activity, spectroscopic and density functional theory calculations

“…Referenced to bipyridine ligand system, a more conjugated ligand (pyridylbenzimidazole) has been chosen to motive the electronic properties of this class of Re(I) tricarbonyl compounds. To get an insight into the inuence of presence of free benzimidazole arm close to the coordination sphere on the electronic structure of 16 (5)) (Scheme 1)) have been synthesized in a similar way to 1-3. With the aim of understanding the electronic transitions of 1-5, time-dependent density functional theory calculations (TDDFT) were undertaken in both singlet and triplet states.…”

Green‐Light‐Induced PhotoCORM: Lysozyme Binding Affinity towards MnI and ReI Carbonyl Complexes and Biological Activity Evaluation

“…For the class of metal carbonyl complexes, change of the metal ion (rhenium, manganese, iron, ruthenium, molybdenum, tungsten), and the axial ligand as well as extension of the ancillary ligand conjugation system led to modulation of the M–CO that influence in turn the electron density and consequently the energy of the incident light. Manganese(I) and ruthenium(II) carbonyl complexes have been widely studied in the context of CORMs because of their rich photochemical properties , . By extending the conjugation system of the ancillary ligand, Mascharak and his co‐workers succeed in shift the MLCT band of Mn I and Ru II photoCORMs into the visible region and thus visible‐light LEDs were used as excitation source …”