The Reactions of β-Hydroxychalcones and 2-Acetoxy-1,3-diarylpropan-1,3-diones with Lead Tetraacetate
作者:Kazu Kurosawa、Akira Moriyama
DOI:10.1246/bcsj.47.2717
日期:1974.11
The reaction of β-hydroxychalcone with leadtetraacetate gave benzil. The reaction of 4,4′-dimethoxy-β-hydroxychalcone gave 2-acetoxy-1,3-di(p-methoxyphenyl)propan-1,3-dione and 4,4′-dimethoxybenzil. The reactions of 2-acetoxy-1,3-diarylpropan-1,3-diones yielded 2,2-diacetoxy-1,3-diarylpropan-1,3-diones and benzils respectively. The formation of the benzils from β-hydroxychalcones and 2-acetoxy-1,3-diarylpropan-1
A facile and efficient synthesis of 1,3-diketones was developed by the gold(I)-catalyzed regioselective hydration of ynones at room temperature. This methodology employed 2.5 mol% of PPh3AuCl and 3 mol% of AgOTf as a simple catalytic system without any special phosphine ligand and was compatible with a wide range of substrates, giving rise to 1,3-diaryl, 1-alkyl-3-aryl-, and 1,3-dialkyl-1,3-diketones
A quantitative reactivity scale for electrophilic fluorinating reagents
作者:Neshat Rozatian、Ian W. Ashworth、Graham Sandford、David R. W. Hodgson
DOI:10.1039/c8sc03596b
日期:——
experimentation in the absence of quantitative values for electrophilicities. Here we report an experimentally-determined kinetic reactivity scale for ten N–F fluorinating reagents, including Selectfluor™, NFSI, Synfluor™ and several N-fluoropyridinium salts, in CH3CN. The reactivity scale, which covers eight orders of magnitude, employs para-substituted 1,3-diaryl-1,3-dicarbonyl derivatives to measure relative
Mechanochromic luminescence (ML) refers to the luminescence color and/or intensity change of solid-state materials induced by mechanical perturbations. For organic molecular solids, this phenomenon is related to the specific packing modes and orientations of individual fluorophores, which could give rise to different excited-state interactions. The molecular solids of difluoroboron dibenzoylmethane (BF2dbm) derivatives were previously found to exhibit reversible ML at room temperature and are promising as self-healing optical materials. In this report, we aim to shed some light on the mechanism of BF2dbm ML by trying to understand the excited-state interactions among solid-state BF2dbm molecules and elucidate how these interactions change upon mechanical stimulation. We first investigated the optical properties of monomeric, dimeric, and polymeric BF2dbm derivatives in optically dilute solutions and demonstrated unambiguously that BF2dbm moieties have a propensity to form H-aggregates. Next, we studied the physical properties of these boron complexes in the solid state including their crystal structures, fluorescence emissions, and mechanochromic luminescence. By correlating solution data with the solid-state characterization results, it was concluded that two coupled processes, force-induced emissive H-aggregate formation and energy transfer to the emissive H-aggregates, are responsible for the observed BF2dbm ML in the solid state.
机械变色发光(ML)是指固态材料在机械扰动诱导下发生的发光颜色和/或强度变化。对于有机分子固体来说,这种现象与单个荧光团的特定堆积模式和取向有关,它们可能会产生不同的激发态相互作用。以前曾发现二氟硼二苯甲酰甲烷(BF2dbm)衍生物分子固体在室温下表现出可逆的 ML,有望成为自修复光学材料。在本报告中,我们试图了解固态 BF2dbm 分子之间的激发态相互作用,并阐明这些相互作用在机械刺激下是如何变化的,从而揭示 BF2dbm ML 的机理。我们首先研究了单体、二聚体和聚合 BF2dbm 衍生物在光学稀释溶液中的光学特性,并明确证明 BF2dbm 分子有形成 H-聚集体的倾向。接下来,我们研究了这些硼复合物在固态下的物理性质,包括它们的晶体结构、荧光发射和机械变色发光。通过将溶液数据与固态表征结果相关联,我们得出结论:在固态下观察到的 BF2dbm ML 是由两个耦合过程造成的:力诱导的发射性 H-聚集体的形成和向发射性 H-聚集体的能量转移。