Mason Helen E, Howard Judith A K, Sparkes Hazel A
Department of Chemistry, Durham University, South Road, Durham DH1 3LE, England.
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, England.
Acta Crystallogr C Struct Chem. 2020 Sep 1;76(Pt 9):927-931. doi: 10.1107/S2053229620010530. Epub 2020 Aug 29.
The synthesis and structures of three isoxazole-containing Schiff bases are reported, namely, (E)-2-{[(isoxazol-3-yl)imino]methyl}phenol, CHNO, (E)-2-{[(5-methylisoxazol-3-yl)imino]methyl}phenol, CHNO, and (E)-2,4-di-tert-butyl-6-{[(isoxazol-3-yl)imino]methyl}phenol, CHNO. All three structures contain an intramolecular O-H...N hydrogen bond, alongside weaker intermolecular C-H...N and C-H...O contacts. The C-O(H) and imine C=N bond lengths were consistent with structures existing in the enol rather than the keto form. Despite having dihedral angles <25°, none of the compounds were observed to be strongly thermochromic, unlike their anil counterparts; however, all three compounds showed a visible colour change upon irradiation with UV light.
报道了三种含异恶唑的席夫碱的合成及结构，即(E)-2-{[(异恶唑-3-基)亚氨基]甲基}苯酚，C₉H₇NO₂、(E)-2-{[(5-甲基异恶唑-3-基)亚氨基]甲基}苯酚，C₁₀H₉NO₂和(E)-2,4-二叔丁基-6-{[(异恶唑-3-基)亚氨基]甲基}苯酚，C₁₇H₂₅NO₂。所有三种结构都包含分子内O-H...N氢键，以及较弱的分子间C-H...N和C-H...O接触。C-O(H)和亚胺C=N键长与烯醇形式而非酮形式的结构一致。尽管二面角<25°，但与它们的苯胺类似物不同，没有观察到任何一种化合物具有强烈的热致变色性；然而，所有三种化合物在紫外光照射下都显示出可见的颜色变化。
