- Bi-stable spin-crossover in charge-neutral [Fe(R-ptp)2] (ptp = 2-(1: H -pyrazol-1-yl)-6-(1 H -tetrazol-5-yl)pyridine) complexes
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Bi-stable charge-neutral iron(ii) spin-crossover (SCO) complexes are a class of switchable molecular materials proposed for molecule-based switching and memory applications. In this study, we report on the SCO behavior of a series of iron(ii) complexes composed of rationally designed 2-(1H-pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine (ptp) ligands. The powder forms of [Fe2+(R-ptp-)2]0 complexes tethered with less-bulky substituents - R = H (1), R = CH2OH (2), and R = COOCH3 (3; previously reported) - at the 4-position of the pyridine ring of the ptp skeleton showed abrupt and hysteretic SCO at or above room temperature (RT), whereas complex 5 featuring a bulky pyrene substituent showed incomplete and gradual SCO behavior. The role of intermolecular interactions, lattice solvent, and electronic nature of the chemical substituents (R) in tuning the SCO of the complexes is elucidated.
- Senthil Kumar, Kuppusamy,Vela, Sergi,Heinrich, Beno?t,Suryadevara, Nithin,Karmazin, Lydia,Bailly, Corinne,Ruben, Mario
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- Attachment of a RuII Complex to a Self-Folding Hexaamide Deep Cavitand
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We report the design, synthesis and characterization of a new RuII metallocavitand that is catalytically active in alkene epoxidation reactions. The elaboration of the resorcin[4]arene's aromatic cavity produced a self-folding, deep hexaamide cavitand featuring a single diverging terpyridine (tpy) group installed at its upper rim. The construction of the metallocavitand involved the initial chelation of a RuIII chloride complex by the tpy ligand followed by the incorporation of 2-(phenylazo)pyridine (azpy) as an ancillary ligand. The resulting RuII chloro complex was converted into the catalytically active aqua counterpart by a ligand exchange process.
- Korom, Sa?a,Ballester, Pablo
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supporting information
p. 12109 - 12112
(2017/09/12)
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- Synthesis of 2,6-di(pyrazol-1-yl)-4-bromomethylpyridine, and its conversion to other 2,6-di(pyrazol-1-yl)pyridines substituted at the pyridine ring
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Two routes to 2,6-di(pyrazol-1-yl)-4-hydroxymethylpyridine (1) from 2,6-dihydroxy-isonicotinic acid, in four and six steps, are reported. Reaction of 1 with 48% HBr yields 2,6-di(pyrazol-1-yl)-4-bromomethylpyridine (2), which is a powerful precursor to a range of new tridentate ligands for transition metals functionalised at the pyridine ring. As a proof of principle, we describe the further elaboration of 2 to give two 2,6-di(pyrazol-1-yl)pyridines bearing nucleobase substituents, and the back-to-back ligand 1,2-bis[2,6-di(pyrazol-1-yl)pyrid-4-yl]ethane. Crystal structures of two of these new derivatives are presented.
- Elha?k, Jér?me,Pask, Christopher M.,Kilner, Colin A.,Halcrow, Malcolm A.
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p. 291 - 298
(2007/10/03)
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- Synthesis of bisfunctionalized-oligopyridines bearing an ester group
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The synthesis of 2,2′-bipyridine, 1,10-phenantroline and 2,2′:6′,2″-terpyridine substituted by an ethylester function is described. The 5- and 6-methyl-2,2′-bipyridines bearing an ethylester group on the 6′ position as well as the ethyl 6,6″-dimethyl-2,2′:6′,2″-terpyridine-4′- carboxylate moiety were synthesized via a Stille cross-coupling reaction, starting from bromo-picoline building blocks. A radical bromination of the methyl-oligopyridine gave selectively the corresponding benzylic bromide derivatives in fair yield.
- Ulrich, Gilles,Bedel, Sébastien,Picard, Claude,Tisnès, Pierre
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p. 6113 - 6115
(2007/10/03)
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- Carboxylate derivatives of oligopyridines
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The key compound ethyl 2,6-dibromopyridine-4-carboxylate was prepared in two steps starting from the commercially available citrazinic acid. By using the Stille coupling reaction ethyl 2,6- dibromopyridine-4-carboxylate was converted to 2,2'-bipyridines, 2,2':6',2''-terpyridines and 2,2':6',2'':6'',2''':6''',2''''- quinquepyridines which bear a carboxylate functional group directly attached to the central pyridine ring.
- Fallahpour, Reza-Ali
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p. 1138 - 1142
(2007/10/03)
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