- The synthesis and complexation of a cobaltocenium-based redox-active cryptand containing the phenanthroline unit
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The synthesis and characterization of a cobaltocenium-based redox-active cryptand 3 containing a phenanthroline unit is described. Complex formation (with Ca2+) was studied by 1H/13C-NMR, and the effects of complexation on the redox properties of 3 were monitored by cyclic voltammetry. The fluorescence spectra of the complexes of 3 and its ferrocene analogue (4) with Eu3+ are also reported, and the low intensity of the fluorescence in each case attributed to carbonyl coordination of Eu3+ rather than metallocene quenching.
- Hall, C.Dennis,Djedovic, Natasha
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- Pyridyldiimine macrocyclic ligands: Influences of template ion, linker length and imine substitution on ligand synthesis, structure and redox properties
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A series of 2,6-diiminopyridine-derived macrocyclic ligands have been synthesized via [2 + 2] condensation around alkaline earth metal triflate salts. The inclusion of a tert-butyl group at the 4-position of the pyridine ring of the macrocyclic synthons results in macrocyclic complexes that are soluble in common organic solvents, thereby enabling a systematic comparison of the physical properties of the complexes by NMR spectroscopy, mass spectrometry, solution-phase UV–Vis spectroscopy, cyclic voltammetry and single-crystal X-ray crystallography. Solid-state structures determined crystallographically demonstrate increased twisting in the ligand, concurrent with either a decrease in ion size or an increase in macrocycle ring size (18, 20, or 22 membered rings). The degree of folding and twisting within the macrocycle can be quantified using parameters derived from the Npyr-M-Npyr bond angle and the relative orientation of the pyridinediimine (PDI) and pyridinedialdimine (PDAI) fragments to each other within the solid state structures. Cyclic voltammetry and UV–Vis spectroscopy were used to compare the relative energies of the imine π* orbital of the redox active PDI and PDAI components in the macrocycle when coordinated to redox inactive metals. Both methods indicate the change from a methyl to hydrogen substitution on the imine carbon lowers the energy of the ligand π* system.
- Thierer, Laura M.,Wang, Qiuran,Brooks, Sam H.,Cui, Peng,Qi, Jia,Gau, Michael R.,Manor, Brian C.,Carroll, Patrick J.,Tomson, Neil C.
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supporting information
(2021/02/16)
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- Synthesis, Src kinase inhibitory and anticancer activities of 1-substituted 3-(N-alkyl-N-phenylamino)propane-2-ols
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A series of 3-(N-alkyl-N-phenylamino)propan-2-ol derivatives were synthesized from epichlorohydrine in a multi-step strategy and were evaluated as Src kinase inhibitors. First, epoxy ring opening of epichlorohydrine was carried out in the presence of N-alkylanilines to yield 3-(N-alkyl-N-phenylamino)-1-chloro-propan-2-ol derivatives using Ca(OTf)2 as catalyst based on our previous studies [1]. Second, ring closure was performed under basic conditions to afford N-epoxymethyl N-alkylaniline derivatives. Finally, the epoxide ring opening with four different secondary amines and three nucleobases afforded the final products, i.e., a series of β-amino alcohols. All compounds were screened for their inhibitory activity against Src kinase and anticancer activity on human breast carcinoma cells, BT-20 cell line. Among all compounds, 3-N-methyl-N-phenylamino-1-(pyrrolidin-1-yl)propan-2-ol (13b) exhibited the highest inhibitory potency (IC50 = 66.1 μM) against Src kinase. Structure-activity relationship studies suggested that the incorporation of bulky groups at position 1 and N-substitution with groups larger than methyl moiety, reduced the inhibitory potency of the compound significantly. Compounds 3-(N-ethyl-N-phenylamino-)-1-(4-methylpiperazin-1-yl)propan-2-ol (14c) and 3-(N-ethyl-N-phenylamino)-1-(thymine-1-yl)propan-2-ol (17) were found to inhibit the growth of breast carcinoma cells by approximately 45-49% at concentration of 50 μM.
- Sharma, Deepti,Sharma, Raman K.,Bhatia, Sumati,Tiwari, Rakesh,Mandal, Deendayal,Lehmann, Jessica,Parang, Keykavous,Olsen, Carl E.,Parmar, Virinder S.,Prasad, Ashok K.
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p. 1164 - 1172
(2011/11/05)
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- A Novel High-yield Route to Organic Derivatives of Group 2 Metals; X-Ray Structure of 4(py)14>*py (OTf = OSO2CF3) and NMR Spectral Characterisation of (R = SiMe3)
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Treatment of M(OTf)2 with 2 MOAr or 2 MNR2 (M = Na or K, Ar = C6H2But2-2,6-Me-4; R = SiMe3) in thf at 0 deg C affords 4, (M = Sr 5 or Ba 6), (M = Ca 7 or Sr 8) or 9; the new compounds 1-3 have been characterised by their NMR spectra in pyridine, and the pyridine adduct of 3 also by X-ray diffraction: crystalline 2-OTf)2(μ-OTf)2(μ3-OTf)4(py)14>*py 10 is unique among metal triflates in having three different bonding modes for the -OTf ligand.
- Frankland, Andrew D.,Hitchcock, Peter B.,Lappert, Michael F.,Lawless, Gerard A.
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p. 2435 - 2436
(2007/10/02)
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- Regiospecific Ring Opening of Epoxides with Cyanotrimethylsilane on Solid Bases: Reaction Features, and Role of Metal Cations of Solid Bases
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A new attempt of utilizing solid acids and bases for ring opening of epoxides with Me3SiCN was investigated.Solid strong bases such as calcium oxide and magnesium oxide catalyzed the regio- and chemoselective ring opening of epoxides with Me3SiCN much more effectively than homogeneous catalysts.On CaO and MgO, the reactions of unsymmetrical epoxides with Me3SiCN afforded 3-trimethylsiloxyalkanenitriles in high yields through regio- and stereoselective attack of cyanide ion on the less substituted epoxycarbon.Additionally, on CaO, 2,3-epoxy-1-alkanol derivatives were selectively converted to the corresponding C-3 opened products by the attack of cyanide ion.In these cases no isocyanides were formed.It was suggested that CaO acted as a bifunctional catalyst; the lattice oxide anions of CaO activated Me3SiCN, and simultaneously calcium ions promoted the ring opening of epoxyalkanol as Lewis acid sites.
- Sugita, Keisuke,Ohta, Akihisa,Onaka, Makoto,Izumi, Yusuke
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p. 1792 - 1799
(2007/10/02)
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- Studies on trifluoromethanesulfonic acid. Part 2. Conductivities of solutions of metal trifluoromethanesulfonates and other bases in trifluoromethanesulfonic acid
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Electrical conductivity measurements are reported for solutions in trifluoromethanesulfonic acid of a number of simple and complex bases, including univalent and divalent metal trifluoromethanesulfonates.The univalent metal salts, water, aniline, and acetic acid behave as fully dissociated bases, while the alkaline earth metal salts show considerable ion association.The trifluoromethanesulfonate anion appears to have an abnormally high mobility, as compared to the metal cations, and is believed to conduct by a proton-transfer mechanism.Dissociation constants for some weak organic bases and association constants for strontium and barium trifluoromethanesulfonates are estimated.Sulfuric acid behaves as a weak electrolyte, while sulfur trioxide is effectively a non-electrolyte.The conductivities of potassium nitrate and potassium dihydrogenphosphate are consistent with the formation of the nitryl cation and the phocphate acidium ion, respectively.
- Russell, David G.,Senior, John B.
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