Analysis of Ion Pairing in Solid State and Solution in p-Cymene Ruthenium Complexes

Abstract

The importance of ion pairing in different fields of chemistry is widely recognized. In this work, we have synthesized a set of cationic p-cymene ruthenium complexes of general formula [(p-cym)X-ray diffraction studies on selected complexes revealed relatively strong anion−cation interactions in the solid state mainly based on N−H•••X (X = Cl, F, O) and C−H•••π interactions, also observed in the DFT-modeled complexes in the gas phase. Moreover, NMR studies showed that they exist as intimate ion pairs in solution and, remarkably, as head-to-tail quadruples in the particular case of the cation [(p-cym)Ru(MeIm)(κ 2 -O^N−L1)] + ([1] + ) with Cl − and BPh 4 − as counteranions. Furthermore, a value of ΔG = −2.9 kcal mol −1 at 299 K has been estimated for the equilibrium {− } in concentrated CDCl 3 solutions. In addition, preliminary studies concerning the cytotoxic properties against HeLa cell lines of the derivatives suggested a positive effect derived from the presence of the lipophilic BPh 4 − anion and also from the NH group of the benzimidazolyl fragment.

Resveratrol enhances A1 and hinders A2A adenosine receptors signaling in both HeLa and SH-SY5Y cells: Potential mechanism of its antitumoral action

“…130 µM) in both cell lines analyzed here after 24 h of RSV treatment. This value was ten-fold higher than that achieved with cisplatin after treatment for 24 h (IC 50 = 16.3 mM) and 48 h (IC 50 = 14.9 mM) as previously reported by our group in these HeLa cells (57). In human gastric cancer cells these IC longer exposure to this phytochemical, as previously described in human colorectal cancer cells (64) and human lung adenocarcinoma A549 cells (65).…”

“…130 µM) in both cell lines analyzed here after 24 h of RSV treatment. This value was ten-fold higher than that achieved with cisplatin after treatment for 24 h (IC 50 = 16.3 μM) and 48 h (IC 50 = 14.9 μM) as previously reported by our group in these HeLa cells ( 57 ). In human gastric cancer cells these IC 50 values ranged from 150 to 200 µM [BGC823 200 μM ( 58 ), MGC803 127 μM ( 59 )].…”

New Triazolyl N^N Bidentate Rh(III), Ir(III), Ru(II) and Os(II) Complexes: Synthesis and Characterization, Probing Possible Relations between Cytotoxicity with Transfer Hydrogenation Efficacy and Interaction with Model Biomolecules

“…In addition, the metal derivatives were generally not active against A549 and HEK293 except for the C2 , C7 , which had BPh 4 − as a counterion. Such improved activity may be due to the increased lipophilicity induced by the BPh 4 − counter ion, which enabled efficient cell membrane crossing by the metallodrug, as previously reported [ 26 , 27 , 28 , 29 ]. These two complexes displayed good (EC 50 < 10 µM) to moderate (EC 50 < 50 µM) cytotoxic activities against cancer cell lines, but low (EC 50 between 60 µM and 200 µM) activity against normal cells (BHK21).…”

Matrix Effects on Photoluminescence and Oxygen Sensitivity of a Molecular Ruby

“…The smaller Φ PL and a shorter τ 778 of CrBPh 4 compared to CrBF 4 (Figure 3c) is ascribed to π‐π and CH–π stacking interactions of the electron rich phenyl groups of the borate anions with the pyridine rings of the ddpd ligands. Consequently, C−H moieties of the borate anions can approach the emissive Cr III center and open additional multiphonon relaxation pathways [12f] which reduce Φ PL and τ 778 [18h] . To confirm this, spectroscopic studies of CrBPh 4 were performed in deaerated benzonitrile (PhCN).…”