5315-25-3Relevant articles and documents
Synthesis of a new tetradentate chelator with 1-Hydoroxy-2(1H)-pyridinone (HOPO) as chelating unit: Interaction with Fe (III), solution thermodynamics and DFT studies
Baral, Minati,Dash, Dibyajit,Kanungo, B. K.
, (2020)
1,2-Hydroxypyridinone (1,2-HOPO) forms very stable transition metal complexes that may be useful in various ways, among these the iron complexes have been long used for the treatment of iron overload diseases like β-Thalassemia. A new tetradentate chelator, 1-hydroxy-N-[3-[2-[2-[3-[(1-hydroxy-6-oxo-pyridine-2carbonyl)amino]propoxy]ethoxy]ethoxy]propyl]-6-oxo-pyridine-2-carboxamide (L) having two 1,2-HOPO units with long chain amine backbone has been synthesized and characterized through various techniques like TLC, solubility, melting point, FT-IR, 1H NMR, 13C NMR, ESI-MS, UV–Vis and emission spectroscopy. The protonation constants of the ligand were determined by both potentiometrically as well as spectrophotometrically in aqueous medium at 25° ±1 °C. The solution thermodynamics of the ligand its Fe(III) complexes in aqueous solution were also studied. The pKa values for ligand are found to be 7.34 and 6.06 and the formation constant of metal complex (M2L3) is found to be logβ230 = 42.45. To support the experimental data, theoretical calculation at DFT level of theory was done using GGA (Gradient Generalized Approximation) with BLYP functional and DZP basis set. The results of calculated thermodynamic properties suggest that, ΔG follows the same trend of protonation as determined by potentiometry and spectrophotometry. Studies of the DFT optimized structures of LH2, LH? shows that, there is π stacking interaction between the hydroxypyridinone rings in the species and the intramolecular π-stacking interaction decreases as the distance between two pyridine ring increases upon deprotonation and was found to be 2.7, 3.2 and 14.6 ? for LH2, LH? and L?2 respectively.
NEW COMPOUND
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Paragraph 0316; 0320, (2019/11/26)
PROBLEM TO BE SOLVED: To provide a new compound that does not have structural similarity to ceramide and has excellent CERT inhibitory activity. SOLUTION: The present invention provides a new compound of structural formula (I). A bond group -X- is cis-cyclopropyl-, R1, R2, R3, R4, and R5 independently represent a hydrogen atom, a halogen atom, a linear or branched C1-C8 alkyl group that may have a halogen atom, or OR6. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2020,JPOandINPIT
Photocatalytic CO2 Reduction by Trigonal-Bipyramidal Cobalt(II) Polypyridyl Complexes: The Nature of Cobalt(I) and Cobalt(0) Complexes upon Their Reactions with CO2, CO, or Proton
Shimoda, Tomoe,Morishima, Takeshi,Kodama, Koichi,Hirose, Takuji,Polyansky, Dmitry E.,Manbeck, Gerald F.,Muckerman, James T.,Fujita, Etsuko
supporting information, p. 5486 - 5498 (2018/05/17)
The cobalt complexes CoIIL1(PF6)2 (1; L1 = 2,6-bis[2-(2,2′-bipyridin-6′-yl)ethyl]pyridine) and CoIIL2(PF6)2 (2; L2 = 2,6-bis[2-(4-methoxy-2,2′-bipyridin-6′-yl)ethyl]pyridine) were synthesized and used for photocatalytic CO2 reduction in acetonitrile. X-ray structures of complexes 1 and 2 reveal distorted trigonal-bipyramidal geometries with all nitrogen atoms of the ligand coordinated to the Co(II) center, in contrast to the common six-coordinate cobalt complexes with pentadentate polypyridine ligands, where a monodentate solvent completes the coordination sphere. Under electrochemical conditions, the catalytic current for CO2 reduction was observed near the Co(I/0) redox couple for both complexes 1 and 2 at E1/2 = -1.77 and -1.85 V versus Ag/AgNO3 (or -1.86 and -1.94 V vs Fc+/0), respectively. Under photochemical conditions with 2 as the catalyst, [Ru(bpy)3]2+ as a photosensitizer, tri-p-tolylamine (TTA) as a reversible quencher, and triethylamine (TEA) as a sacrificial electron donor, CO and H2 were produced under visible-light irradiation, despite the endergonic reduction of Co(I) to Co(0) by the photogenerated [Ru(bpy)3]+. However, bulk electrolysis in a wet CH3CN solution resulted in the generation of formate as the major product, indicating the facile production of Co(0) and [Co-H]n+ (n = 1 and 0) under electrochemical conditions. The one-electron-reduced complex 2 reacts with CO to produce [Co0L2(CO)] with νCO = 1894 cm-1 together with [CoIIL2]2+ through a disproportionation reaction in acetonitrile, based on the spectroscopic and electrochemical data. Electrochemistry and time-resolved UV-vis spectroscopy indicate a slow CO binding rate with the [CoIL2]+ species, consistent with density functional theory calculations with CoL1 complexes, which predict a large structural change from trigonal-bipyramidal to distorted tetragonal geometry. The reduction of CO2 is much slower than the photochemical formation of [Ru(bpy)3]+ because of the large structural changes, spin flipping in the cobalt catalytic intermediates, and an uphill reaction for the reduction to Co(0) by the photoproduced [Ru(bpy)3]+.
