Chemistry of ruthenium with some phenolic ligands: synthesis, structure and redox properties

Reaction of three phenolate ligands, viz. salicylaldehyde (HL1), 2-hydroxyacetophenone (HL2) and 2-hydroxynaphthylaldehyde (HL3), (abbreviated in general as HL, where H stands for the phenolic proton) with [Ru(PPh3)3Cl2] in 1¦1 mole ratio gives complexes of the type[Ru(PPh3)2(L)Cl2]. The structure of the [Ru(PPh3)2(L2)Cl2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium isO2P2Cl2 with a cis-trans-cis geometry, respectively. The [Ru(PPh3)2(L)Cl2] complexes are one-electron paramagnetic (low-spin d5, S=½) and show rhombic ESR spectra in 1¦1 dichloromethane-toluene solution at 77 K. In dichloromethane solution the [Ru(PPh3)2(L)Cl2] complexes show several intense LMCT transitions in the visible region. Reaction between the phenolic ligands and [Ru(PPh3)3Cl2] in 2¦1 mole ratio in the presence of a base affords the [Ru(PPh3)2(L)2] complexes in two isomeric forms. 1H NMR spectra of one isomer shows that it does not have any C2 symmetry and has the cis-cis-cis disposition of the three sets of donor atoms. 1H NMR spectra of the other isomer shows that it has C2 symmetry. The structure of the isomer of the [Ru(PPh3)2(L1)2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is O4P2 with a cis-trans-cis disposition of the carbonylic oxygens, phenolate oxygens and phosphorus atoms, respectively. The [Ru(PPh3)2(L)2] complexes are diamagnetic (low-spin d6, S=O) and show intense MLCT transitions in the visible region. Cyclic voltammetry on the [Ru(PPh3)2(L)Cl2] complexes shows a ruthenium(III)---ruthenium(II) reduction near -0.3 V versus SCE and a ruthenium(III)---ruthenium(IV) oxidation in the range 1.08-1.24 V versus SCE. Cyclic voltammetry on both isomers of the [Ru(PPh3)2(L)2] complexes shows a ruthenium(II)---ruthenium(III) oxidation within 0.09-0.41 V versus SCE, followed by a ruthenium(III)-ruthenium(IV) oxidation within 1.31-1.52 V versus SCE

Exosomal RNA: Interplay and Therapeutic Potential

Exosomal RNA has emerged as a crucial mediator of intercellular communication, enabling the transfer of genetic information between cells. This intricate signaling system holds great promise for unraveling complex cellular processes and advancing therapeutic applications. This review provides an in-depth examination of the current state of knowledge regarding exosomal RNA, emphasizing its role in intercellular signaling and its relevance to various physiological and pathological conditions. Furthermore, we explore the potential therapeutic applications that leverage exosomal RNA, opening new avenues for innovative treatments across diverse medical domains. The nuanced interplay of exosomal RNA presents a fertile ground for further investigation and application, promising advancements in both fundamental biology and clinical interventions

Design and Implementation of Dynamic Load Balancing Algorithms for Rollback Reduction in Optimistic PDES

This article discusses the load transfer mechanism between logical processes and migration of of logical processes between several pairs of physical processors

Design And Implementation Of Dynamic Load Balancing Algorithms For Rollback Reduction In Optimistic Pdes

Two algorithms are proposed for dynamic load balancing which reduce the number of rollbacks in an optimistic parallel discrete event simulation (PDES) system. The first algorithm is based on the load transfer mechanism between lps while the other is based on the principle of evolutionary strategy. Both algorithms are implemented on a cluster of heterogeneous workstations to determine their performance. The experimental results show that the algorithm based on the load transfer is effective when the grain size is greater than ten milliseconds, while the one based on process migration yields good performance only for grain sizes of 20 milliseconds or larger. In both cases, the speed up ranges mostly between 1 and 2 using four processors

Chemistry of osmium in N<SUB>2</SUB>P<SUB>2</SUB>Br<SUB>2</SUB> coordination sphere: synthesis, structure and reactivities

A family of three mixed-ligand osmium complexes of type [Os(PPh3)2(N-N)Br2], where N-N=2,2&#8242;-bipyridine (bpy), 4,4&#8242;-dimethyl-2,2&#8242;-bipyridine (Me2bpy) and 1,10-phenanthroline (phen), have been synthesized and characterized. The complexes are diamagnetic (low-spin d6, S=0) and in dichloromethane solution they show intense MLCT transitions in the visible region. The two bromide ligands have been replaced from the coordination sphere of [Os(PPh3)2(phen)Br2] under mild conditions by a series of anionic ligands L (where L=quinolin-8-olate (q), picolinate (pic), oxalate (Hox) and 1-nitroso-2-naphtholate (nn)) to afford complexes of type [Os(PPh3)2(phen)(L)]+, which have been isolated and characterized as the perchlorate salt. The structure of the [Os(PPh3)2(phen)(pic)]ClO4 complex has been determined by X-ray crystallography. The PPh3 ligands occupy trans positions and the picolinate anion is coordinated to osmium as a bidentate N,O-donor forming a five-membered chelate ring. The [Os(PPh3)2(phen)(L)]+ complexes are diamagnetic and show multiple MLCT transitions in the visible region. The [Os(PPh3)2(N-N)Br2] complexes show an osmium(II)-osmium(III) oxidation (-0.02 to 0.12 V vs. SCE) followed by an osmium(III)-osmium(IV) oxidation (1.31 to 1.43 V vs. SCE). The [Os(PPh3)2(phen)(L)]+ complexes display the osmium (II)-osmium (III) oxidation (0.26 to 0.84 V vs. SCE) and one reduction of phen (-1.50 to -1.79 V vs. SCE). The osmium (III)-osmium (IV) oxidation has been observed only for the L=q and L=Hox complexes at 1.38 V vs. SCE and 1.42 V vs. SCE respectively. The osmium(III) species, viz. [OsIII(PPh3)2(N-N)Br2]+and [OsIII(PPh3)2(phen)(L)]2+, have been generated both chemically and electrochemically and characterized in solution by electronic spectroscopy and cyclic voltammetry

Unusual transformation of N-arylbenzohydroxamic acids mediated by osmium. Formation of organometallic complexes of osmium(III)

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Oxidation of rhodium(I) by hydroxamic acids. Synthesis, structure, and electrochemical properties of bis(hydroxamate) complexes of rhodium(III)

This article does not have an abstract