Organic dye molecules with excited state proton transfer property gain huge scientific interest owing to the design flexibility and functional diversity. However, the anti-counterfeiting of a single dye molecule through intra- and intermocular excited state proton transfer (ESIPT and ESPT) has yet to be achieved. This study demonstrates a simple and efficient approach to realize the anti-counterfeiting of a single dye molecule in a PMMA film. We control the 1-hydroxypyrene-2-carbaldehyde (HP) to be fluorescent or not through two different solvents based on ESIPT and ESPT mechanisms. Furthermore, we investigate the detailed information of excited-state dynamics for HP in two solvents, aiming at exploring the mechanisms of totally different luminescence property, through the femtosecond transient absorption spectroscopy. Meanwhile, the theoretical TDDFT research sheds light on the correlation between molecular structure and luminescence character. Specifically, the fluorescence of the molecule in acetonitrile is quenched by an ESIPT (127 fs) induced intersystem crossing (11.8 ps) whereas the ESPT (195 fs) and following aldehyde group rotation (26.5 ps) make the molecule to exhibit a strong luminescence property in dimethyl sulfoxide. The results are promising and offer new avenues to realize the greener and sustainable anti-counterfeiting of a single dye molecule.

由于设计的灵活性和功能的多样性，具有激发态质子转移性质的有机染料分子获得了巨大的科学兴趣。然而，尚未实现通过染料内和分子间激发态质子转移（ESIPT和ESPT）的单个染料分子的防伪。这项研究演示了一种简单有效的方法来实现PMMA膜中单个染料分子的防伪。我们基于ESIPT和ESPT机制通过两种不同的溶剂控制1-羟基py-2-甲醛（HP）的荧光性或不荧光性。此外，我们通过飞秒瞬态吸收光谱研究了两种溶剂中HP激发态动力学的详细信息，旨在探索完全不同的发光特性的机理。同时，TDDFT的理论研究揭示了分子结构与发光特性之间的关系。具体而言，乙腈中分子的荧光通过ESIPT（127 fs）诱导的系统间穿越（11.8 ps）猝灭，而ESPT（195 fs）和醛基旋转（26.5 ps）之后使该分子表现出强发光特性在二甲基亚砜中。结果令人鼓舞，并为实现单一染料分子的绿色和可持续防伪提供了新途径。5 ps）使该分子在二甲基亚砜中显示出强大的发光特性。结果令人鼓舞，并为实现单一染料分子的绿色和可持续防伪提供了新途径。5 ps）使该分子在二甲基亚砜中显示出强大的发光特性。结果令人鼓舞，并为实现单一染料分子的绿色和可持续防伪提供了新途径。