The photophysical and photochemical properties of the sulfonyl azide‐based fluorescent probe DNS–Az and its reduction product DNS by hydrogen sulfide (H2S) have been investigated theoretically. The calculated results indicated the first excited states of DNS–Az was dark state (oscillator strength less than 0.03) and DNS was bright state (oscillator strength more than 0.1), which determined the predicted radiative rate kr of DNS–Az was much smaller than that of DNS, meanwhile, due to more larger reorganization energy of DNS–Az, its predicted internal conversion rate kic was four times larger than that of DNS; moreover, owing to the effect of heavy atom from sulfur atom in DNS–Az, its predicted intersystem crossing rate kisc was seven times larger than that of DNS, thus the calculated fluorescence quantum yield of DNS–Az was only 2.16% and that of DNS was more than 77.2%, the above factors is the basis for DNS–Az molecule to function as a fluorescent probe. Regarding both DNS‐Az and DNS molecules, their maximum Huang‐Rhys factors, which are less than unity, signify the reliability of 0–0 transitions between their S0 and S1 electronic states. In addition, for DNS, our simulated emission peak of the 0–0 transition is 515 nm, a value that exhibits enhanced accuracy and coherence when compared to the experimental datum of 528 nm. The reaction mechanism of DNS‐Az generating DNS by H2S has been investigated too, according to the potential energy profile, we found that the fluorescent probe firstly protonated, then this organic ion broke down into DNS with the aid of a proton.

中文翻译：

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丹磺酰基荧光探针检测硫化氢发光及反应机理的理论研究


从理论上研究了基于磺酰叠氮化物的荧光探针 DNS-Az 及其被硫化氢 (H2S) 还原的产物 DNS 的光物理和光化学性质。计算结果表明，DNS-Az的第一激发态为暗态（振荡强度小于0.03），DNS为亮态（振荡强度大于0.1），这决定了DNS-Az的预测辐射率kr远小于同时，由于DNS-Az的重组能更大，其预测内部转化率kic比DNS大4倍；而且，由于DNS-Az中硫原子重原子的影响，其预测的系间窜越率kisc比DNS大7倍，因此计算得到的DNS-Az荧光量子产率仅为2.16%，而DNS的荧光量子产率仅为2.16%。大于77.2%，以上因素是DNS-Az分子作为荧光探针发挥作用的基础。对于 DNS-Az 和 DNS 分子，它们的最大 Huang-Rhys 因子小于 1，表示其 S0 和 S1 电子态之间 0-0 跃迁的可靠性。此外，对于 DNS，我们模拟的 0-0 跃迁发射峰为 515 nm，与 528 nm 的实验数据相比，该值表现出更高的准确性和一致性。还研究了H2S生成DNS-Az的反应机制，根据势能分布，我们发现荧光探针首先质子化，然后该有机离子在质子的帮助下分解成DNS。