Abstract：
(R)-(-)-Mellein, (3R,4R)-4-hydroxymellein and (3R,4S)-4-hydroxymellein obtained from fungi, i. e. from Diplodia globulosa, were investigated as a class of natural products presenting ESIPT (excited state intramolecular proton transfer) phenomenon, through fluorescence and CPL (circularly polarized luminescence). The study was preceded by the assessment of the absolute configuration through ECD and VCD (electronic and vibrational circular dichroism) spectroscopies in addition to NMR spectra. It is found that ESIPT takes place in these systems very rapidly, and no dual fluorescence has been observed. The experimental study is backed up by TD-DFT calculations of ECD and CPL spectra, plus MD calculations to follow proton transfer in the excited state and careful analysis of the puckering dynamics of the lactone ring. Deprotonated forms of the three compounds were also investigated by the same chiroptical experimental and theoretical methods, showing how one can find in natural compounds not only biological activity but also biologically compatible sensing probes.
摘要：
(R)-(-)-Mellein,(3R,4R）-4-羟基mellein和（3R，4S）-4-羟基mellein从真菌中获得，也就是来自双创，被研究为一类呈现ESIPT（激发态分子内质子转移）现象的天然产物，通过荧光和CPL（圆偏振发光）。在研究之前，除了NMR光谱外，还通过ECD和VCD（电子和振动圆二色性）光谱法评估了绝对构型。发现ESIPT在这些系统中发生得非常快，并且没有观察到双重荧光。实验研究得到了ECD和CPL光谱的TD-DFT计算的支持，加上MD动力学，以跟踪激发态下的质子转移，并仔细分析内酯环的起皱动力学。还通过相同的手性实验和理论方法研究了三种化合物的去质子化形式，显示了如何在天然化合物中不仅可以找到生物活性，还可以找到生物相容性传感探针。
