- Thermal stability of bidendate nitrogen ligands tethered to multiwall carbon nanotubes
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Bidendate nitrogen ligands, particularly 1,10-phenanthroline, form stable complexes with a variety of divalent metal ions. If these ligands are attached to a stable, inert platform, then they may be used for sequestering transition metal ions from a range of aqueous solutions including many that form components of industrial processes. Alternatively, they may function as a base for the development of durable heterogeneous catalysts. These ligands may be tethered to carboxyl-functionalized carbon nanotubes via an ethylene oxide linker through either an ether or ester bond. The suitability of these adducts for a variety of applications has been assessed using thermogravimetry. Both kinds of adducts are thermally robust with an onset of degradation above 400 °C.
- Howell, Bob A.,Dumitrascu, Adina
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- Environmental sensitivity of Ru(II) complexes: The role of the accessory ligands
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A suite of Ru(II) complexes in which one ligand is pH responsive and the other two are varied in an effort to achieve improved photophysics has been synthesized and their potential as pH reporters assessed. The more general purpose of the study was to examine the role of the accessory ligands in heteroleptic reporter complexes and the degree to which such ligands can affect the performance of luminescent reporters. For this suite of complexes, judicious choice of the accessory ligand can alter both the pKa* and the dynamic range of response. It was found that the emission color and brightness were influenced by pH, but the lifetimes were only weakly affected. Surprisingly, some accessory ligands which should have improved luminescent properties essentially turned off the pH response. Several possible reasons for this observation are explored. It is suggested, and density functional theory (DFT) calculations support, that the relative π* levels of the pH sensitive and the accessory ligands are critical.
- Dixon, Eileen N.,Snow, Michael Z.,Bon, Jennifer L.,Whitehurst, Alison M.,Degraff, Benjamin A.,Trindle, Carl,Demas, James N.
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- Molecular engineering for optical properties of 5-substituted-1,10-phenanthroline-based Ru(ii) complexes
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A series of homo- and heteroleptic Ru(ii) complexes[Ru(phen)3?n(phen-X)n](PF6)2(n= 0-3, X = CN, epoxy, H, NH2) were prepared and characterized. The influence of electron-withdrawing or electron-releasing substituents of the 1,10-phenanthroline ligands on the photo-physical properties was evaluated. It reveals fundamental interests in the fine tuning of redox potentials and photo-physical characteristics, depending both on the nature of the substitution of the ligand, and on the symmetry of the related homo- or heteroleptic complex. These complexes exhibit linear absorption and two-photon absorption (2PA) cross-sections over a broad range of wavelength (700-900 nm) due to absorption in the intra-ligand charge transfer (ILCT) and the metal-to-ligand charge transfer (MLCT) bands. These 2PA properties were more particularly investigated in the 700-1000 spectral range for a family of complexes bearing electro-donating ligands (phen-NH2).
- Beley, Marc,Blanchard-Desce, Mireille,Chevreux, Sylviane,Gros, Philippe C.,Lawson-Daku, Latévi Max,Lemercier, Gilles,Mongin, Olivier,Moreau, Juliette,Rousset, Elodie
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p. 10119 - 10132
(2021/08/03)
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- Dual mechanism of action of 5-Nitro-1,10-phenanthroline against mycobacterium tuberculosis
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New chemotherapeutic agents with novel mechanisms of action are urgently required to combat the challenge imposed by the emergence of drug-resistant mycobacteria. In this study, a phenotypic whole-cell screen identified 5-nitro-1,10-phenanthroline (5NP) as a lead compound. 5NP-resistant isolates harbored mutations that were mapped to fbiB and were also resistant to the bicyclic nitroimidazole PA-824. Mechanistic studies confirmed that 5NP is activated in an F420-dependent manner, resulting in the formation of 1,10-phenanthroline and 1,10-phenanthrolin-5-amine as major metabolites in bacteria. Interestingly, 5NP also killed naturally resistant intracellular bacteria by inducing autophagy in macrophages. Structure-activity relationship studies revealed the essentiality of the nitro group for in vitro activity, and an analog, 3-methyl-6-nitro-1,10-phenanthroline, that had improved in vitro activity and in vivo efficacy in mice compared with that of 5NP was designed. These findings demonstrate that, in addition to a direct mechanism of action against Mycobacterium tuberculosis, 5NP also modulates the host machinery to kill intracellular pathogens.
- Kidwai, Saqib,Park, Chan-Yong,Mawatwal, Shradha,Tiwari, Prabhakar,Jung, Myung Geun,Gosain, Tannu Priya,Kumar, Pradeep,Alland, David,Kumar, Sandeep,Bajaj, Avinash,Hwang, Yun-Kyung,Song, Chang Sik,Dhiman, Rohan,Lee, Ill Young,Singh, Ramandeep
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supporting information
(2017/11/04)
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- A ruthenium tetrazole complex-based high efficiency near infrared light electrochemical cell
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We report on the exploitation of a new tetrazole-substituted 1,10-phenanthroline and a 2,2′-bipyridine (bpy) ancillary ligand modified with an electron-donating group in cationic ruthenium complexes. This complex, placed in between two electrodes without any polymer, demonstrates high efficiency near-infrared (NIR) electroluminescence (EL). The comparison between bpy and its methyl-substituted ancillary ligand shows that the cationic Ru tetrazolate complex containing methyl groups exhibits a red shift in the EL wavelength from 620 to 800 nm compared to [Ru(bpy)3]2+ and an almost twofold reduction in the turn-on voltage, i.e., from 5 to 3 V, with respect to 5-tetrazole-1,10-phenanthroline. An external quantum efficiency of 0.95% for the dimethyl derivative is demonstrated, which is a remarkable result for non-doped NIR light electrochemical cells based on ruthenium polypyridyl.
- Shahroosvand, Hashem,Abaspour, Saeid,Pashaei, Babak,Radicchi, Eros,De Angelis, Filippo,Bonaccorso, Francesco
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p. 6211 - 6214
(2017/07/10)
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- Crosslinked polysaccharides and methods of making and using crosslinked polysaccharides
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This invention relates to methods of crosslinking polysaccharides to form crosslinked polysaccharides, and more particularly, to crosslinked polysaccharides that may be incorporated in fluids useful in, for example, applications requiring a crosslinked viscoelastic gel. In one embodiment, the present invention provides a method of crosslinking a polysaccharide comprising the steps of: providing a metal coordinating group having a reactive site, derivatizing a polysaccharide with the metal coordinating group to produce a derivatized polysaccharide having bidentate ligands, and crosslinking the derivatized polysaccharide having bidentate ligands with a metal ion to form a metal ligand coordination complex.
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Page/Page column 2; 4
(2008/06/13)
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- On the chlorine addition to the C(5)-C(6) bridge and the N-oxidation of 1,10-phenanthroline
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It was found that under the influence of aqueous hypochlorite 1,10-phenanthroline (1) is initially transformed into 5,6-dichloro-5,6-dihydro-1,10-phenanthroline (2) and 5-chloro-6-hydroxy-5,6-dihydro-1,10-phenanthroline (8). The latter readily undergoes subsequent transformations either into a mixture of 5,5-dichloro-6-oxo-5,6-dihydro-1,10-phenanthroline (4) and 5,6-dioxo-5,6-dihydro-1,10-phenanthroline (5) or into the known 5,6-epoxy-1,10-phenanthroline (3) depending on the acidic or alkaline conditions, respectively. In contrast to the flat molecule of the starting 1, that of the dichloro derivative (2) being twisted at the central bond of the bipyridine system can be easily N-oxidized to di-N-oxide (11). Both 2 and its di-N-oxide (11) in the presence of sodium isopropoxide at 0°C freely lost hydrogen chloride and returned to the fully aromatic system of 5-chloro-1,10-phenanthroline (9) and its di-N-oxide (13), respectively.
- Antkowiak, Roza,Antkowiak, Wieslaw Z.
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p. 893 - 909
(2007/10/03)
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- Is the formation of 1,10-phenanthroline di-N-oxide possible?
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5,6-Dichloro-5,6-dihydro-1,10-phenanthroline (2) was found as an additional product of the hypochlorous acid action on 1,10-phenanthroline. When treated with MCPBA the product of the chlorine addition yielded a corresponding di-N-oxide 3, which readily lost hydrogen chloride under the influence of sodium isopropoxide. The resulting monochloro di-N-oxide 5 molecules (assumed to be flat) revealed a satisfactory stability unless the neutral or basic solution was made acidic.
- Antkowiak, Roza,Antkowiak, Wieslaw Z.
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p. 1857 - 1858
(2007/10/03)
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- The synthesis of ascididemin
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A short synthsis of the pentacyclic marine alkaloid ascididemin 1 (four steps, 21% yield) from 1,10-phenanthroline 16 is described. The key step, photocyclisation of the quinoneimine 14 in sulphuric acid, is the first such aza stilbene photocyclisation of a quinoneimine. Intermediate 14 is prepared in a single, but low yielding, step from the quinone 4 in an aza Wadsworth-Emmons reaction, or in much better yield from the epoxide 17 by treatment with 2- iodoaniline and triethylaluminium, followed by oxidation with barium manganate.
- Moody, Christopher J.,Rees, Charles W.,Thomas, Robert
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p. 3589 - 3602
(2007/10/02)
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- Arene Imine Derivatives of Nitrogen Heterocycles: 1a,9b-Dihydrobenzazirinoquinoline, 1a,9b-Dihydrobenzazirinoquinoline and 1a,9b-Dihydroazirinophenanthroline
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The synthesis of the K-imine derivatives of benzoquinoline (1), benzoquinoline (2) and 1,10-phenanthroline (3) are described.The parent nitrogen heterocycles were oxidized with sodium hypochlorite to the corresponding K-oxides, 4, 6 and 8, which in turn were reacted with sodium azide.The resulting azido alcohols were then cyclized with triethyl phosphite to the title compounds 5, 7 and 9.The oxirane ring cleavage in benzoquinoline 5,6-oxide (4) and in benzoquinoline 5,6-oxide (6) by sodium azide proceeded by the predicted regioselectivity: 4 gave trans-5-azido-5,6-dihydro-6-benzoquinolinol (11) and trans-6-azido-5,6- dihydro-5-benzoquinolinol (10) as the major and minor products respectively, and 6 yielded solely trans-6-azido-5,6-dihydro-5-benzoquinolinol (12).The latter compound proved by X-ray analysis to crystallize as a hydrogen bonded dimer.
- Abu-Shqara, Elias,Blum, Jochanan
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p. 1197 - 1200
(2007/10/02)
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