Reaction of N-(aryl)picolinamide (HL-R; R ¼ OCH 3 , CH 3 , H, Cl and NO 2 ) with ruthenium trichloride or [Ru(DMSO) 4 Cl 2 ] in refluxing 2-methoxyethanol in the presence of a base (NEt 3 ) affords tris complexes of the type [Ru(L-R) 3 ]. The structure of the [Ru(L-OCH 3 ) 3 ] complex has been determined by X-ray crystallography. In these complexes the amide ligands are coordinated to the metal center as monoanionic bidentate N,N-donors. All the [Ru(L-R) 3 ] complexes are one-electron paramagnetic and show rhombic ESR spectra at 77 K. They also show intense LMCT transitions in the visible region. Cyclic voltammetry on all the complexes shows a ruthenium(III)/ruthenium(IV) oxidation within the range of 0.89 to 1.21 V vs. SCE and a ruthenium(III)/ruthenium(II) reduction within the range of À0.22 to À0.41 V vs. SCE. Representative one-electron oxidized and reduced complexes, viz. [Ru IV (L-H) 3 ] þ and [Ru II (L-H) 3 ] À , respectively, have also been generated in solution and characterized spectroscopically as well as electrochemically.

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A series of acylguanidine-modified zanamivir analogs were synthesized and their inhibitory activities against the NAs of avian influenza viruses (H1N1 and H3N2) were evaluated. In particular, zanamivir derivative , with a hydrophobic naphthalene substituent, exhibits the best inhibitory activity against group-1 NA with an IC50 of 20 nM.

Reaction of chloranilic acid (H2ca) with [Os(bpy)2 Br2] (bpy = 2,2'-bipyridine) affords a dinuclear complex of type [{Os(bpy)2}2 (ca)]2+, isolated as the perchlorate salt. A similar reaction of H2ca with [Os(PPh3)2 (pap)Br2] (pap = 2-(phenylazo)pyridine) affords a dinuclear complex of type [{Os(PPh3)2 (pap)}2 (ca)]2+ (isolated as the perchlorate salt) and a mononuclear complex of type [Os(PPh3)2 (pap)(ca)]. Reaction of H2ca with [Os(PPh3)2(CO)2(HCOO)2] gives a dinuclear complex of type [{Os(PPh3)2(CO)2}2 (r-ca)], where r-ca is the two electron reduced form of the chloranilate ligand. The structures of the [{Os(PPh3)2 (pap)}2 (ca)](ClO4)2, [Os(PPh3)2 (pap)(ca)], and [{Os(PPh3)2(CO)2}2 (r-ca)] complexes have been determined by X-ray crystallography. In the [{Os(bpy)2}2 (ca)]2+ and [{Os(PPh3)2 (pap)}2 (ca)]2+ complexes, the chloranilate dianion is serving as a tetradentate bridging ligand. In the [Os(PPh3)2 (pap)(ca)] complex, the chloranilate dianion is serving as a bidentate chelating ligand. In the [{Os(PPh3)2(CO)2}2 (r-ca)] complex, the reduced form of the chloranilate ligand (r-ca(4-)) is serving as a tetradentate bridging ligand. All the four complexes are diamagnetic and show intense metal-to-ligand charge-transfer transitions in the visible region. The [Os(PPh3)2 (pap)(ca)] complex shows an Os(II)-Os(III) oxidation, followed by an Os(III)-Os(IV) oxidation on the positive side of a standard calomel electrode. The three dinuclear complexes show two successive oxidations on the positive side of SCE. The mixed-valent Os(II)-Os(III) species have been generated in the case of the two chloranilate-bridged complexes by coulometric oxidation of the homovalent Os(II)-Os(II) species. The mixed-valent Os(II)-Os(III) species show intense intervalence charge-transfer transitions in the near-IR region.