Search

Dicationic ruthenium(II)-p-cymene complexes containing curcumin ligands (curcH = curcumin, bdcurcH = bisdemethoxycurcumin) and ionic N-methyl-1,3,5-triaza-7-phosphaadamantane [PTA-Me]X (X = BF4 or I) have been synthesized and fully characterized for the first time. The solid-state structure of [Ru(p-cym)(curc)(PTA-Me)][SO3CF3][BF4] has also been determined by single-crystal X-ray diffraction. Modest antiproliferative activities of the complexes were observed against cisplatin-sensitive and cisplatin-resistant human ovarian carcinoma cells (A2780 and A2780cisR, respectively) and nontumorigenic human embryonic kidney (HEK293) cells. [ABSTRACT FROM AUTHOR]

Five bidentate ligands derived from quinoline-2-carboxylic acid, i.e. 2-(1 H -benzimidazol-2-yl)quinoline ( L1 ), 2-(1-benzyl-1 H -benzimidazol-2-yl)quinoline ( L2 ), 2-[1-(2,3,5,6-tetramethylbenzyl)-1 H -benzimidazol-2-yl]quinoline ( L3 ), 2-[1-(4-chlorobenzyl)-1 H -benzimidazol-2-yl]quinoline ( L4 ), and 2-[1-(4-methylbenzyl)-1 H -benzimidazol-2-yl]quinoline ( L5 ) were synthesized. Treatment of L1-5 with [RuCl 2 ( p -cymene)] 2 and KPF 6 afforded six-coordinate piano-stool Ru(II) complexes, namely, [RuCl(L1)( p -cymene)]PF 6 ( C1 ), [RuCl(L2)( p -cymene)]PF 6 ( C2 ), [RuCl(L3)( p -cymene)]PF 6 ( C3 ), [RuCl(L4)( p -cymene)]PF 6 ( C4 ), and [RuCl(L5)( p -cymene)]PF 6 ( C5 ). Synthesized compounds were characterized with different techniques such as 1 H and 13 C NMR, FT-IR, and UV–vis spectroscopy. The solid state structure of L1 and C3 was confirmed by single-crystal X-ray diffraction analysis. The single crystal structure of C3 verified coordination of L3 to the Ru(II) center. The Ru(II) center has a pseudo-octahedral three legged piano stool geometry. The complexes C1-5 were tested as catalysts for the catalytic oxidation of benzyl alcohol to benzaldehyde in the presence of periodic acid (H 5 IO 6 ) (Substrate/Catalyst/Oxidant = 1/0.01/0.5). The best result was obtained with C2 (3 h→90%). [ABSTRACT FROM AUTHOR]

Multicomponent molecular systems that exhibit large amplitude movements controlled by external inputs – namely, molecular machines – are extensively investigated both for their basic science interest and for their potential applications in technology and medicine. Light is a convenient stimulus to operate molecular machines because it can provide both an energy supply to feed their motion and an analytical signal to monitor their state. Research in the past two decades has shown that the unique and highly tunable structural, photophysical, photochemical and redox properties of Ru(II) polypyridine complexes are advantageous tools for implementing a light-induced response in molecular devices and machines. Here we describe the latest progresses in the realization of artificial nanoscale machines that use such metal complexes to process light signals. We will show the level of creativity and sophistication reached in this research area by describing a few selected examples. [ABSTRACT FROM AUTHOR]

Treatment of [(p-cymene)RuCl2]2with HSp-Tol or HSCH2Ph in the presence of K[PF6] gave the cationic dinuclear cymene–ruthenium(II) complexes [(p-cymene)2Ru2(μ-Cl)(μ-Sp-Tol)2][PF6] (1) and [(p-cymene)2Ru2(μ-Cl)(μ-SCH2Ph)2][PF6] (2), respectively, which have been characterized by IR, NMR spectroscopies and mass spectrometry along with microanalyses. Their crystal structures were determined by single-crystal X-ray diffraction analyses. The structures of the cationic complexes contain the unusualpseudo-trigonal-bipyramidal Ru2S2Cl framework without a ruthenium–ruthenium single bond. The twop-cymene–ruthenium units are held together by two bridging thiolates and one bridging chloride. [ABSTRACT FROM AUTHOR]

The cationic complex [(pymox-Me2)RuCl2]+BF4−was found to be a highly effective catalyst for the C−H bond oxidation reaction of arylalkanes in water. For example, the treatment of ethylbenzene (1.0 mmol) with t-BuOOH (3.0 mmol) and 1.0 mol % of the Ru catalyst in water (3 mL) cleanly produced PhCOCH3at room temperature. Both a large kinetic isotope effect (kH/kD= 14) and a relatively large Hammett value (ρ = −1.1) suggest a solvent-caged oxygen rebounding mechanism via a Ru(IV)-oxo intermediate species. [ABSTRACT FROM AUTHOR]