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The discovery of new light-triggered prodrugs based on ruthenium (II) complexes is a promising approach for photoactivated chemotherapy (PACT). The light-mediated activation of "strained" Ru(II) polypyridyl complexes resulted in ligand release and produced a ligand-deficient metal center capable of forming covalent adducts with biomolecules such as DNA. Based on the strategy of exploiting structural distortion to activate photochemistry, biologically active small molecules were coordinated to a Ru(II) scaffold to create light-triggered dual-action agents. Thirteen new Ru(II) complexes with pyridyl-pyrazol(in)e ligands were synthesized, and their photochemical reactivity and anticancer properties were investigated. Isomeric bidentate ligands were investigated, where "regular" ligands (where the coordinated nitrogens in the heterocycles are linked by C-C atoms) were compared to "inverse" isomers (where the coordinated nitrogens in the heterocycles are linked by C-N atoms). Coordination of the regular 3-(pyrid-2-yl)-pyrazol(in)es to a Ru(II) bis-dimethylphenanthroline scaffold yielded photoresponsive compounds with promising photochemical and biological properties, in contrast to the inverse 1-(pyrid-2-yl)-pyrazolines. The introduction of a phenyl ring to the 1N-pyrazoline cycle increased the distortion in complexes and improved ligand release upon light irradiation (470 nm) up to 5-fold in aqueous media. Compounds 1-8, containing pyridyl-pyrazol(in)e ligands, were at least 20-80-fold more potent than the parent pyridyl-pyrazol(in)es, and exhibited biological activity in the dark, with half-maximal inhibitory concentration (IC50) values ranging from 0.2 to 7.6 μM in the HL60 cell line, with complete growth inhibition upon light irradiation. The diversification of coligands and introduction of a carboxylic acid into the Ru(II) complex resulted in compounds 9-12, with up to 146-fold improved phototoxicity indices compared with complexes 1-8.

A synthetic route to the preparation of cobalt(III) complexes coordinated by bidentate phenylthioether ligands is described. Complexes of the type ((2-(X-phenylthio)ethylamine)- N , S)bis(ethylenediamine)cobalt(III) perchlorate, [(en)2Co(S (X-phenyl)CH2CH2 N H2)](ClO4)3, where X = 4-methoxy (2a), 4-methyl (2b), 3-methyl (2c), nothing (2d), 3-methoxy (2e), 4-bromo (2f) and 3-bromo (2g) were prepared. The synthetic route involves reaction of trans -dichloridobis(ethylenediamine)cobalt(III) chloride with NH2CH2CH2SC6H4X to produce cis -[(en)2CoCl(N H2CH2CH2SC6H4X)]Cl2 (1a – g). Formation of the Co–S bond, completing the ring closure, is then accomplished by removing the coordinated chlorido by addition of AgClO4 in sulfolane. Complexes were characterized by 1H and 13C NMR spectroscopy, UV-Vis spectroscopy and elemental analysis. In addition, the solid-state structure (X-ray) of the monohydrate of 2d confirms the coordination mode of the ligand. Preliminary kinetic investigations in basic solution show that the Co–S bond is broken resulting in the formation of [(en)2Co(OH)(N H2CH2CH2SC6H4X)]2+. At 15.0°C, a Hammett Plot is linear (r 2 = 0.981) with ρ = 2.24 ± 0.13. We have prepared a series of cobalt(III) complexes coordinated in a κ 2N,S manner by substituted phenylthioether ligands. The preparation is a two-step process starting with trans- dichloridobis(ethylenediamine)cobalt(III) chloride. NMR spectroscopy was used to characterize the complexes. In addition, the presence of an intense ligand-to-metal charge-transfer transition in the UV region confirms that a sulfur atom is bonded to the cobalt(III) center. In basic solution, the Co–S bond is broken, presumably by the classical SN1CB mechanism. The rate of the cleavage reaction increases as the electron-withdrawing ability of the phenyl substituent increases. (Image credit: Lee Roecker.) [ABSTRACT FROM AUTHOR]

The crystal structure and a Hirshfeld surface analysis of the substituted anilinium salt 4-(dimethylazaniumyl)-2-hydroxyanilinium dichloride monohydrate, C8H14N2O+·2Cl- ·H2O, at low temperature (90 K) are presented. The organic cation is essentially planar: the r.m.s. deviation of its non-hydrogen atoms (aside from the two methyl groups) is 0.0045 A °. The methyl carbons are 1.3125 (12) A ° and 1.1278 (12) A ° either side of the mean plane. The crystal packing involves extensive hydrogen bonding of types O--H...Cl, N--H...Cl, N--H...OW, and OW--HW...Cl (where W = water), which arrange into chains of R2 4(12) motifs that combine to form corrugated layers parallel to (101). Atom-atom contacts for the cation primarily involve hydrogen, leading to the most abundant coverage percentages being 51.3% (H...H), 23.0% (H...Cl), 12.9% (H....O), and 9.7% (C...H). [ABSTRACT FROM AUTHOR]

The synthesis, crystal structure and spectroscopic analysis of (E)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-3-(4-chlorophenyl)prop-2-en-1-one (C17H13ClO3), a substituted chalcone, are described. The overall geometry of the molecule is largely planar (r.m.s. deviation = 0.1742 JA), but slightly kinked, leading to a dihedral angle between the planes of the benzene rings at either side of the molecule of 8.31 (9)°. In the crystal, only weak interactions determine the packing motifs. These include C--H--O and C--H--Cl hydrogen bonds and n-n overlap of aromatic rings. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of a monoclinic polymorph of 2-amino-5-chlorobenzophenone oxime, C13H11ClN2O, are presented. The molecular conformation results from twisting of the phenyl and 2-amino-5-chloro benzene rings attached to the oxime group, which subtend a dihedral angle of 80.53 (4)°. In the crystal, centrosymmetric dimers are formed as a result of pairs of strong O--H--N hydrogen bonds. A comparison is made to a previously known triclinic polymorph, including differences in atom-atom contacts obtained via a Hirshfeld-surface analysis. [ABSTRACT FROM AUTHOR]