High Pressure & Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India.
High Pressure & Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Oct 5;259:119903. doi: 10.1016/j.saa.2021.119903. Epub 2021 May 3.
Curcumin, described as a wonder drug owing to various medicinal, viz. anticancer, antiviral, anti-inflammatory etc., properties, can also be seen as a model molecular system to study strong intra-molecular OH----O hydrogen bonds which govern its physico-chemical properties. The study of these hydrogen bonds is important to understand its binding characteristics. Here, we present systematic in-situ variable temperature studies of curcumin in the range 350-75 K using infrared spectroscopy to analyse the effects of external stresses on molecular structure and hydrogen bonding network. The results have been well supported by Raman spectroscopic studies. Our studies show striking difference in the nature of the two intra-molecular hydrogen bonds, generally considered equivalent, which form at the edges of the molecule. Also, the strongest intra-molecular hydrogen bond involving the enol group, present at the centre of the molecule, depicts a remarkable temperature induced strengthening upon cooling. The studies further indicate that the compound does not show any drastic structural transition in the measured temperature range. However, subtle spectral changes associated with reorientations of the hydrogen bonds are noticed across 210 K. These results will be useful to predict reaction pathways during chemical complexation of curcumin.
姜黄素因其具有多种药用特性，如抗癌、抗病毒、抗炎等，被誉为“灵丹妙药”，它也可以被视为研究强分子内 OH----O 氢键的模型分子体系，这些氢键决定了它的物理化学性质。研究这些氢键对于理解其结合特性非常重要。在这里，我们使用红外光谱法在 350-75 K 的范围内对姜黄素进行了系统的原位变温研究，以分析外部压力对分子结构和氢键网络的影响。拉曼光谱研究很好地支持了这些结果。我们的研究表明，在分子边缘形成的两个通常被认为等效的分子内氢键的性质存在显著差异。此外，分子中心处存在的最强的涉及烯醇基团的分子内氢键在冷却时表现出显著的温度诱导增强。这些研究进一步表明，在测量的温度范围内，该化合物没有显示出任何剧烈的结构转变。然而，在 210 K 左右，注意到与氢键重定向相关的微妙光谱变化。这些结果将有助于预测姜黄素在化学络合过程中的反应途径。
