The mysterious flashes of light communicated by fireflies conceal a rich and exciting solution spectrochemistry that revolves around the chemiexcitation and photodecay of the fluorophore, oxyluciferin. A triple chemical equilibrium by double deprotonation and keto–enol tautomerism turns this simple molecule into an intricate case where the relative spectral contributions of six chemical species combine over a physiologically relevant pH range, rendering physical isolation and spectral characterization of most of the species unmanageable. To disentangle the individual spectral contributors, here we demonstrate the advantage of chemical oriented multivariate data analysis. We designed a set of specific oxyluciferin derivatives and applied a multivariate curve resolution-alternating least squares (MCR-ALS) procedure simultaneously to an extensive set of pH-dependent spectroscopic data for oxyluciferin and the target derivatives. The analysis provided, for the first time, the spectra of the pure individual components free of contributions from the other forms, their pH-dependent profiles and distributions, and the most accurate to date values for the three equilibrium constants.
萤火虫发出的神秘闪光隐藏着丰富而令人兴奋的溶液光谱
化学,它围绕着荧光体氧
荧光素的
化学激发和光致衰减展开。通过双去质子化和酮烯醇同分异构的三重
化学平衡,这个简单的分子变成了一个复杂的案例,在生理相关的 pH 值范围内,六个
化学物种的相对光谱贡献结合在一起,使得大多数物种的物理分离和光谱特征描述变得难以处理。为了厘清各个光谱贡献者,我们在此展示了以
化学为导向的多元数据分析的优势。我们设计了一组特定的氧
荧光素衍
生物,并将多元曲线解析-交替最小二乘法(MCR-ALS)程序同时应用于氧
荧光素和目标衍
生物的大量与 pH 值相关的光谱数据。该分析首次提供了不含其他形式成分的纯粹单个成分的光谱、其随 pH 值变化的轮廓和分布,以及三个平衡常数迄今为止最精确的值。