- Extension of Azine-Triazole Synthesis to Azole-Triazoles Reduces Ligand Field, Leading to Spin Crossover in Tris-L Fe(II)
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The first examples of azole-Triazole Rat ligands, bidentate L4NMeIm(3-(1-methyl-1H-imidazol-4-yl)-5-phenyl-4-(p-Tolyl)-4H-1,2,4-Triazole) and L4SIm (4-(5-phenyl-4-(p-Tolyl)-4H-1,2,4-Triazol-3-yl)thiazole), have been prepared, by extension of the general synthesis used to access many examples of azine-Triazoles. The tris-L FeII complexes of the azine-Triazoles are consistently low spin (LS). As intended, these new azole-Triazole ligands provide lower field strengths, resulting in high-spin (HS) [FeII(L4NMeIm)3](BF4)2 (1·4H2O) and spin crossover (SCO) active [FeII(L4SIm)3](BF4)2 (2·0.5H2O). Single-crystal structure determinations revealed that at 100 K 1·solvents is HS whereas 2·solvents is LS. Solid-state variable temperature magnetic studies of air-dried crystals showed that the methylimidazole-Triazole complex 1·4H2O remains HS while the thiazole-Triazole complex 2·0.5H2O undergoes a two-step gradual SCO (T1/2 approximately 275 and 350 K). Variable-Temperature Evans method NMR studies of 2, in five different solvents (CD3NO2, CD3CN, CD3COCD3, CD2Cl2, and CDCl3) gave T1/2 values in a relatively narrow range, 214-259 K. These T1/2 values did not correlate with the solvent polarity index P′ (R2 = 0.25) but did correlate with the solvent basicity parameter SB (R2 = 0.90). Variable-Temperature UV-vis studies on a golden yellow CH3CN solution of 2, with monitoring of the d-d transition at 530 nm (? = 39 L mol-1 cm-1 at 293 K) while the solution was heated from 253 to 303 K, showed that the high-spin fraction increased from 0.51 to 0.77. Cyclic voltammetry studies in CH3CN revealed a Fe(III)/Fe(II) redox process that was reversible for 1 and irreversible for 2, with significant tuning of the Epa value: The methylimidazole-Triazole complex 1 is significantly easier to oxidize (0.46 V) than the thiazole-Triazole complex 2 (0.68 V; both vs 0.01 M Ag/AgNO3).
- Brooker, Sally,Singh, Sandhya
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- 5,6,7,8-TETRAHYDRO[1,2,4]TRIAZOLO[4,3-a]PYRAZINE DERIVATIVES AS P2X7 MODULATORS
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The present invention provides a compound of formula (I) or a pharmaceutically acceptable salt thereof wherein A is hydrogen, C1-4alkyl, C3-6cycloalkyl, C1-3alkoxy, C1-3alkoxy C1-4alkyl, C1-2fluoroalkyl, halogen, NR6 R7, optionally substituted heteroaryl (Het), or optionally substituted phenyl, and R1, R2, R3, R4, R5, R6 and R7 are as defined in the description. The compounds or salts are thought to modulate P2X7 receptor function and to be capable of antagonizing the effects of ATP at the P2X7 receptor. The invention also provides the use of the compound or salt in the treatment or prophylaxis of, for example, inflammatory pain, neuropathic pain, visceral pain, rheumatoid arthritis, osteoarthritis or neurodegenerative disorders.
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(2010/11/17)
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