Papers by Christoph Janiak
Journal of Environmental Management
Carbon, 2014
Hybrid materials of platinum nanoparticles (Pt-NP) and thiol-functionalized thermally reduced gra... more Hybrid materials of platinum nanoparticles (Pt-NP) and thiol-functionalized thermally reduced graphite oxide (TRGO-SH), were synthesized by thermal decomposition of the organometallic precursor methylcyclopentadienyl-trimethylplatinum(IV) in dispersions of TRGO-SH in the ionic liquid 1-n-butyl-3-methyl-imidazolium tetrafluoroborate under microwave-assisted heating conditions. For the kinetic stabilization of Pt-NPs on TRGO-SH no additional donor ligands were necessary. The ionic liquid acts as separator of the TRGO-SH graphene sheets and as kinetic stabilizing template in the Pt-nanoparticle formation process. Thiol-functionalization of thermally reduced graphite oxide was carried out using three different synthetic procedures: (1) ring opening of propylene sulfide; (2) xanthate grafting and reduction to thiol; (3) reduction, thioesterfication under Mitsunobu conditions and ester hydrolysis. These three different TRGO-SH materials (1), (2) and (3) had different sulfur contents (1.2, 2.5 and 14 wt.%, respectively) and were used as support materials for platinum nanoparticles. The loading of Pt-NPs on TRGO-SH (1), (2) and (3) was 3.2, 3.5 and 8.8 wt.% with particle diameters determined from transmission electron microscopy of (9 ± 4), (2.5 ± 0.9) and (5 ± 2) nm, respectively.
Related Article: A.B.Caballero, J.K.Maclaren, A.Rodriguez-Dieguez, I.Vidal, J.A.Dobado, J.M.Salas... more Related Article: A.B.Caballero, J.K.Maclaren, A.Rodriguez-Dieguez, I.Vidal, J.A.Dobado, J.M.Salas, C.Janiak|2011|Dalton Trans.|40|11845|doi:10.1039/c1dt10603a
Inorganica Chimica Acta, Oct 1, 2011
Two 2D-polymers of Cu(I), [Cu 2 (l-tp)(CH 3 CN)(l-I)(l 3-I)] n (1) and [Cu 2 (l-tp)(l 3-I) 2 ] n ... more Two 2D-polymers of Cu(I), [Cu 2 (l-tp)(CH 3 CN)(l-I)(l 3-I)] n (1) and [Cu 2 (l-tp)(l 3-I) 2 ] n (2), both obtained from the reaction between copper iodide and 1,2,4-triazolo[1,5-a]pyrimidine (tp) in the presence of KI are described. While in compound 1, tp acts as bridging ligand via N1 and N3 between chair-like [Cu 4 I 4 ] units, in compound 2, tp moieties are placed at both sides of a [Cu n I n ] kinked layer, displaying also a bridging mode but, in this case, through its atoms N3 and N4. These structural differences between both compounds seem to be due to the solvent of crystallization, being acetonitrile for 1 and water for 2. These polymers are the first examples of Cu(I) compounds based on the nucleobase-analog ligand tp.
Acta Crystallographica Section A, Aug 22, 2011
six sandwiches per unit cell stacked in rhomdohedral symmetry [1]. Intercalated Cu atoms and addi... more six sandwiches per unit cell stacked in rhomdohedral symmetry [1]. Intercalated Cu atoms and additional M atoms are incorporated on octahedral and tetrahedral sites in the Van der Waals gaps between MS 2 layers. Here we present the evolution of the complex superstructures of selected intercalated compounds at different temperatures between 14K and 400K using single-crystal X-ray diffraction data. The interest in these compounds is the phase transitions related to ordering of the intercalated atoms and charge-density wave transitions at different temperatures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The polymerization behaviour of a new series of palladium() pre-catalysts in the vinyl-polymeri... more The polymerization behaviour of a new series of palladium() pre-catalysts in the vinyl-polymerization of norbornene has been investigated. Compounds containing [PdCl 4 ] 2Ϫ or [Pd 2 Cl 6 ] 2Ϫ anions and the organic cations [K(18-crown-6)] ϩ , [H 3 O(18-crown-6)] ϩ , [Ph 3 PCH 2 C(O)CH 3 ] ϩ or [Him] ϩ (im = imidazole) can be activated with the Lewis acids methylalumoxane (MAO), tris(pentafluorophenyl)borane, B(C 6 F 5) 3 or a combination of B(C 6 F 5) 3 / triethylaluminum (TEA). The catalytic systems show very high norbornene polymerization activities of up to 10 7 g polymer mol Pd Ϫ1 h Ϫ1. In the case of an activation with B(C 6 F 5) 3 alone it is possible to obtain soluble palladiumcatalyzed poly(norbornene)s which exhibit a fully saturated polymer backbone and a molar mass (M n) between 8 × 10 3 and 3 × 10 5 g mol Ϫ1. The activation process of the pre-catalyst [Ph 3 PCH 2 C(O)CH 3 ] 2 [Pd 2 Cl 6 ] (2C) in combination with B(C 6 F 5) 3 can be followed by multinuclear (1 H, 13 C, 19 F and 31 P) NMR investigations and points to the in situ formation of PdCl 2 which then represents the active species for the polymerization process. The X-ray structure of compound 2C is reported. Scheme 2 Pre-catalysts employed in the vinyl-polymerization of norbornene.
Inorganica Chimica Acta, Aug 1, 2012
A metal-organic-gel catalyst based on Fe(NO 3) 3 and benzene-1,3,5-tricarboxylic acid (H 3 BTC) w... more A metal-organic-gel catalyst based on Fe(NO 3) 3 and benzene-1,3,5-tricarboxylic acid (H 3 BTC) was synthesised and characterized by IR, elemental analysis, thermogravimetry/mass spectrometry (TG/MS), Mössbauer spectroscopy and environmental scanning/transmission electron microscopy (ESEM/TEM). The Fe-BTC metal-organic gel activity was evaluated for the oxidation of primary and secondary alcohols with dilute aqueous 10% H 2 O 2 in water at 90°C to the corresponding aldehydes or ketones with high chemoselectivity and with absence of overoxidation to carboxylic acids. The Fe-BTC gel catalyst allows to use only water as solvent and does not require any organic solvents. The inexpensive and non-toxic iron catalyst works with environmentally friendly hydrogen peroxide at safe, low 10% aqueous H 2 O 2 concentration without the use of phase transfer conditions. A progressive addition of hydrogen peroxide significantly improved the conversion of benzyl alcohol.
La quimioterapia es la forma mas comun del tratamiento del cancer y el cisplatino es uno de los f... more La quimioterapia es la forma mas comun del tratamiento del cancer y el cisplatino es uno de los farmacos mas utilizados desde su descubrimiento por Rosenberg en 1965 (Rosen- berg, 1978). Las desventajas de los farmacos tradicionales basados en Pt(II) (efectos se- cundarios severos y resistencia a algunos tipos de cancer) ha provocado el desarrollo de nuevos compuestos de otros metales como rutenio o iridio. Asi, en los ultimos anos, los complejos de Ir(III) han despertado un gran interes ya que ademas de propiedades anti- tumorales, presentan excelentes propiedades fotofisicas que se pueden aprovechar para estudiar el mecanismo de accion de los mismos y seguir el transcurso de la enfermedad (Lo, Louie & Zhang, 2010). Recientemente, la terapia fotodinamica (PDT) ha surgido como una nueva tecnica prometedora para el tratamiento del cancer. Se trata de un metodo no invasivo en el que se utiliza luz para la activacion de un Farmaco llamado fotosensibilizador (PS). Tras la irradiacion, el PS transfiere energia al oxigeno molecular de las proximidades, generando especies reactivas de oxigeno, tales como oxigeno singlete, que pueden danar irreversiblemente las celulas cancerigenas. En este sentido los complejos de iridio poseen multiples ventajas, entre ellas, largos tiempos de vida media del estado triplete excitado, lo que es fundamental para que se lleve a cabo la transferencia de energia (Zamora, Vigueras, Rodriguez, Santana & Ruiz, 2018). En este trabajo se han sintetizado 5 comple- jos de Ir(III) en los que se ha mantenido fijo el ligando C^N y se ha variado el ligando auxiliar N^N polipiridilo. El objetivo ha sido estudiar el efecto de la longitud y el grado de conjugacion π de estos ligandos auxiliares en las propiedades fotofisicas y biologicas de los complejos metali- cos finales. Los de mayor longitud mostraron un efecto de desactivacion de la luminiscencia, causado por agregacion, y una mejora en los va- lores de citotoxicidad en celulas tumorales humanas cuando se irradian con luz visible (azul). Ademas, se observo que los complejos 1 y 5 se localizan preferentemente en el reticulo endoplasmatico, y que el mecanismo de accion de los mismos implica la inhibicion de la sintesis de proteinas.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Phosphorus Sulfur and Silicon and The Related Elements, Dec 3, 2013
ABSTRACT A new type of cascade cyclization was observed in the phosphorylation reaction of (R,R)-... more ABSTRACT A new type of cascade cyclization was observed in the phosphorylation reaction of (R,R)- or (S,S)-N,N′-bis(salicylidene)cyclohexanediimine with phosphoryltrichloride, which resulted in the formation of bis(chlorophosphorylated) decahydro-2,4-di(2-hydroxyphenyl)benzo[d][1,3,6]oxadiazepine with two new stereogenic phosphorus atoms and two new stereogenic carbon atoms in the oxadiazepine ring in the β-position to phosphorus. During the synthesis, the N atom attacks the phosphorodichloridate group with the formation of the P–N bond to give an asymmetric phosphorus atom and an iminium ion. This compound with six stereogenic centers crystallizes in the monoclinic centrosymmetric space group P21/c and the crystal structure together with solution and solid-state MAS 13C and 31P NMR studies reveals a preferential formation of stereoisomers.
CrystEngComm, 2004
ABSTRACT
Dalton Transactions, 2016
Oxime-based CO-releasing molecules (oximeCORMs) were immobilized with a catechol-modified backbon... more Oxime-based CO-releasing molecules (oximeCORMs) were immobilized with a catechol-modified backbone on maghemite iron oxide nanoparticles (IONPs) to give oximeCORM@IONP. The CO release from the free and immobilized oximeCORMs was measured using the standard myoglobin assay. The oxime-CORM-nanoparticles were coated with dextran for improved water solubility and confined into an alginate shell for protection and separation from the surrounding myoglobin assay to allow for CO release studies by UV/Vis absorption without interference from highly-absorptive oximeCORM@IONP. Half-lifes of the oxime-based polymer-confined alginate@dextran@oximeCORM@IONPs were estimated at 20°C to 814 ± 23 min, at 37°C to 346 ± 83 min and at 50°C to 73 ± 1 min. The alginate@dextran@oximeCORM@IONP composite showed a further decrease of the half-life of CO release to 153 ± 27 min at 37°C through local magnetic heating of the susceptible iron oxide nanoparticles with application of an external alternating magnetic field (31.7 kA m −1 , 247 kHz, 39.9 mTesla). The activation energy for the CO release from molecular dicarbonylchlorido(imidazole-2-carbaldehydeoxime)(alkoxycarbonyl)ruthenium(II) complexes is determined to be ∼100 kJ mol −1 for five different imidazole-oxime derivatives. † Electronic supplementary information (ESI) available: Synthesis for oximebased CORMs, NMR, IR and ESI-mass spectra, myoglobin assay, leaching experiments, DLS experiments, TEM measurements, toxicity tests, and activation energy. See
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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Papers by Christoph Janiak