Chemotherapeutic Activities of New η6-p-Cymene Ruthenium(II) and Osmium(II) Complexes with Chelating SS and Tridentate SNS Ligands

A series of new chelating bidentate (SS) alkylimidazole-2-thione-Ru(II)/Os(II) complexes (3ai, 3aii, 3aiii, 3bii/4aiii, 4bi, 4bii), and the tridentate (SNS) pyridine-2,6-diylimidazole-2-thione-Ru(II)/Os(II) complexes (5bi, 5civ/6bi, 6ci, 6civ) in the forms [MII(cym)(L)Cl]PF6 and [MII(cym)(L)]PF6 (M = Ru or Os, cym = η6-p-cymene, and L = heterocyclic derivatives of thiourea) respectively, were successfully synthesized. Spectroscopic and analytical methods were used to characterize the complexes and their ligands. Solid-state single-crystal X-ray diffraction analyses revealed a "piano-stool" geometry around the Ru(II) or Os(II) centers in the respective complexes. The complexes were investigated for in vitro chemotherapeutic activities against human cervical carcinoma (HeLa) and the non-cancerous cell line (Hek293) using the MTT assay. The compounds 3aii, 5civ, 5bi, 4aiii, 6ci, 6civ, and the reference drug, 5-fluorouracil were found to be selective toward the tumor cells; the compounds 3ai, 3aiii, 3bii, 4bi, 4bii, and 6bi, which were found not to be selective between normal and tumor cell lines. The IC50 value of the tridentate half-sandwich complex 5bi (86 ± 9 μM) showed comparable anti-proliferative activity with the referenced commercial anti-cancer drug, 5-fluorouracil (87 ± 15 μM). The pincer (SNS) osmium complexes 6ci (36 ± 10 μM) and 6civ (40 ± 4 μM) were twice as effective as the reference drug 5-fluorouracil at the respective dose concentrations. However, the analogous pincer (SNS) ruthenium complex 5civ was ineffective and did not show anti-proliferative activity, even at a higher concentration of 147 ± 1 μM. These findings imply that the higher stability of the chelating (SS) and the pincer (SNS) ligand architectures in the complexes improves the biological (anti-proliferative) activity of the complexes by reducing the chance of ligand dissociation under physiological conditions. In general, the pincer (SNS) osmium complexes were found to be more cytotoxic than their ruthenium analogues, suggesting that the anti-proliferative activity of the imidazole-2-thione-Ru/Os complexes depends on the ligand's spatial coordination, the nature of the metal center, and the charge of the metal complex ions.

Phase Transition of High-Surface-Area Glycol-Thermal Synthesized Lanthanum Manganite

Cubic and rhombohedral phases of lanthanum manganite were synthesized in a high-pressure reactor. A mixture of La and Mn nitrates with ethylene glycol at a synthesis temperature of 200 °C and a calcination temperature of up to 1000 °C, resulted in a single-phase perovskite, LaMnO₃ validated using X-ray diffraction. Significant changes in unit cell volumes from 58 to 353 ų were observed associated with structural transformation from the cubic to the rhombohedral phase. This was confirmed using structure calculations and resistivity measurements. Transmission electron microscopy analyses showed small particle sizes of approximately 19, 39, 45, and 90 nm (depending on calcination temperature), no agglomeration, and good crystallinity. The particle characteristics, high purity, and high surface area (up to 33.1 m²/g) of the material owed to the inherent PAAR reactor pressure, are suitable for important technological applications, that include the synthesis of perovskite oxides. Characteristics of the synthesized LaMnO₃ at different calcination temperatures are compared, and first-principles calculations suggest a geometric optimization of the cubic and rhombohedral perovskite structures.

Crystal structure of chlorido-(η 6-toluene)(5,5′-dimethyl-2,2′-bipyridine-κ2 N,N′)ruthenium(II) hexafluoridophosphate(V) ─ acetone (1/1) C22H26ClN2ORuPF6

C22H26ClN2ORuPF6, triclinic, P 1 ‾ $\overline{1}$ (no. 2), a = 10.2106(4) Å, b = 10.8139(4) Å, c = 11.1963(4) Å, α = 93.765(2)°, β = 90.418(1)°, γ = 94.324(2)°, V = 1229.98(8) Å3, Z = 2, R gt (F) = 0.0251, wR ref (F 2) = 0.0683, T = 100 K.

Crystal structure of chlorido-(η 6-toluene)(2,2′-bipyridine-κ2 N,N′)ruthenium(II) hexafluorophosphate, C17H16ClN2RuPF6

C17H16ClN2RuPF6, monoclinic, P21/c (no. 14), a = 14.4426(9) Å, b = 8.3311(5) Å, c = 16.413(1) Å, β = 109.2690°, V = 1864.2(2) Å3, Z = 4, R gt (F) = 0.0309, wR ref (F 2) = 0.0697, T = 173 K.

Crystal structure of 3,3′-(pyridine-2,6-diylbis(methylene))bis(1-propyl-1H-imidazol-3-ium) ditetrafluoroborate, C19H27B2F8N5

C19H27N5, orthorhombic Pbca (no. 61), a = 9.8515(12) Å, b = 16.508(2) Å, c = 29.817(3) Å, β = 90°, V = 4849.3(10) Å3, Z = 8, R gt (F) = 0.0409, wR ref(F 2) = 0.1082.

Synthesis and Characterization of Ag/Al2O3 Catalysts for the Hydrogenation of 1-Octyne and the Preferential Hydrogenation of 1-Octyne vs 1-Octene

Catalysts featuring 2, 5, and 10 wt % silver supported on alumina were prepared by the deposition precipitation method and activated under hydrogen. All catalysts were characterized by Brunauer-Emmett-Teller (BET) measurements, inductively coupled plasma-optical emission spectrometry (ICP-OES), backscattered electron scanning electron microscopy (BSE-SEM), high-resolution transmission electron microscopy (HR-TEM), hydrogen-temperature-programmed reduction (H₂-TPR), H₂-chemisorption, thermogravimetric analysis (TGA), infrared (IR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, and isopropylamine (IPA) TPD and evaluated in a continuous plug flow fixed-bed reactor. Metal nanoparticles with average sizes of 4.5, 11.5, and 21.1 nm were identified by HR-TEM for the 2, 5, and 10 wt % Ag/Al₂O₃ catalysts, respectively. A conversion of 99% was observed for 1-octyne over particles between 10 and 15 nm in size, with stable operation up to 24 h (decreasing thereafter) at a temperature of 140 °C and a pressure of 30 bar in the competitive hydrogenation reaction. No conversion of 1-octene was noted in competitive reactions (mixed 1-octyne and 1-octene feed) but rather a gain of 1-octene throughout the 72 h time-on-stream. The performance of all catalysts was influenced by both the metal and support, where the latter impacted the overall acidity of the catalysts, thus affecting their long-term stability.

Synthesis and characterization of amine-functionalized supported phosphine catalysts and their application in ethylene oligomerization

ABSTRACT A series of phosphorus and nitrogen-based ethylene oligomerization ligands of the type Ph2PN(X)PPh2 where X = i-propyl, n-butyl, ethylbenzene and cyclohexyl substituents are reported. These ligands were functionalized to enable tethering on amino-silica. The free ligands, amino-silica and the tethered ligands were characterized by BET, XRD, IR, TGA and NMR. The catalysts were tested for ethylene oligomerization using Cr(acac)3 (acac = acetylacetonate) as the precursor and MMAO (modified methylaluminoxane) as the activator. The activity and selectivity of these catalysts to 1-octene was monitored at 45 bar ethylene in the temperature range of45-100 °C. The activity of the supported catalysts was comparable to their homogeneous counterparts, surpassing them in some cases and selectivities to 1-octene in the C8 products were as high as 99 wt%. The steric effect of the substituent on the ligand as well as that of the support was found to influence the activity and product distribution. Keywords: 1-hexene, 1-octene, ethylene oligomerization, phosphine ligands, silica, supported catalysts

A new polymorph of 1-(4-nitrophenyl)-1H-benzimidazole (C13H9N3O2)

C13H9N3O2, monoclinic, P21/c (no. 14), a = 3.7375(1) Å, b = 27.9680(6) Å, c = 10.2595(2) Å, β = 95.5120(10)°, V = 1067.47(4) Å3, Z = 4, R gt (F) = 0.0370, wR ref (F 2) = 0.0975, T = 100 K.

Crystal structure of bis{(2-pyridinyl)-1-phenyl-1-isopropylmethanolato-κ2 N,O}nickel, C30H32N2NiO2

C30H32N2NiO2, monoclinic, P 2 1 / c $P{2}_{1}/c$ (no. 14), a = 12.1250(4) Å, b = 13.6413(4) Å, c = 8.1152(3) Å, β = 108.348(2)°, V = 1274.02(7) Å3, Z = 2, R gt (F) = 0.0285, wR ref (F 2) = 0.0711, T = 100 K.

Crystal structure of 4-tert-butyl-2-N-(2-pyridylmethyl)aminophenol, C16H20N2O

C16H20N2O, monoclinic, P 2 1 / c $P{2}_{1}/c$ (no. 14), a = 9.7933(2) Å, b = 17.5290(3) Å, c = 17.1148(3) Å, β = 101.242(1)°, V = 2881.67(9) Å3, Z = 8, R gt(F) = 0.0402, wR ref(F 2) = 0.1106, T = 150(2) K.

Nb2O5 as a radical modulator during oxidative dehydrogenation and as a Lewis acid promoter in CO2 assisted dehydrogenation of octane over confined 2D engineered NiO–Nb2O5–Al2O3

Ordered mesoporous 2D NiO–Nb₂O₅–Al₂O₃ nano-composites were used for CO₂ assisted dehydrogenation of n-octane; and the close proximity of Ni and Nb₂O₅ in the optimised catalyst promoted CO₂ dissociation and substantially prolonged alkane activation.

Ethylene Trimerization over Supported SNS and PNP

ABSTRACT Chromium(III) complexes with sulphur, nitrogen and phosphorus tridentate ligands were synthesized and characterized. These complexes were supported on SiO2 and characterized by BET surface area measurements, XRF, SEM-EDX and FTIR. The complexes were tested for activity and selectivity in the trimerization of ethylene. The substituent's effect and influence on the sulphur on the supported catalysts were studied using the ethyl and the decyl substituted catalysts. The influence of temperature on catalytic performance was evaluated using the PPP supported system. The most active supported catalyst, the decyl substituted SNS catalyst, showed good activity of up to 19 500 g/g Cr h-1 and selectivity of 97.3 % to C6 products (98.2 % 1-hexene). This activity and selectivity were comparable to the homogeneous counterpart's performance that achieved 22 000 g/g Cr h-1 and 98.2 % C6 products (96.7 % 1-hexene), which surpassed the ethyl substituted catalyst, which was not supported, under the same reaction conditions. The supported PPP catalyst activities showed it was sensitive to higher temperatures, but this depends on the supporting technique. Keywords: Ethylene trimerization, sulfanyl ligands, phosphine ligands, supported catalysts.

The effects of metals and ligands on the oxidation of n-octane using iridium and rhodium “PNP” aminodiphosphine complexes

Ir and Rh “PNP” complexes with different ligands are utilized for the oxidation of n-octane. Based on the obtained conversion, selectivity, and the characterized recovered catalysts, it is found that the combination of Ir and the studied ligands does not promote the redox mechanism that is known to result in selective formation of oxo and peroxo compounds [desired species for C(1) activation]. Instead, they support a deeper oxidation mechanism, and thus higher selectivity for ketones and acids is obtained. In contrast, these ligands seem to tune the electron density around the Rh (in the Rh-PNP complexes), and thus result in a higher n-octane conversion and improved selectivity for the C(1) activated products, with minimized deeper oxidation, in comparison to Ir-PNP catalysts.