Novel strategies to optimize the photophysical properties of organic fluorophores are of great significance to the design of imaging probes to interrogate biology. While the 2-(2-hydroxyphenyl)-benzothiazole (HBT) fluorophore has attracted considerable attention in the field of fluorescence imaging, its short emission in the blue region and low quantum yield restrict its wide application. Herein, by mimicking the excited-state intramolecular proton transfer (ESIPT) effect, we designed a series of 2-(2-hydroxyphenyl)-benzothiazole (HBT) derivatives by complexing the heteroatoms therein with a boron atom to enhance the chance of the tautomerized keto-like resonance form. This strategy significantly red-shifted the emission wavelengths of HBT, greatly enhanced its quantum yields, and caused little effect on molecular size. Typically, compounds 12B and 13B were observed to emit in the near-infrared region, making them among the smallest organic structures with emission above 650 nm.

优化有机荧光团光物理性质的新策略对于设计用于询问生物学的成像探针具有重要意义。虽然2-(2-羟基苯基)-苯并噻唑(HBT)荧光团在荧光成像领域引起了广泛关注，但其在蓝色区域的短发射和低量子产率限制了其广泛应用。在此，通过模仿激发态分子内质子转移 (ESIPT) 效应，我们设计了一系列2-(2-羟基苯基)-苯并噻唑(HBT) 衍生物，通过将其中的杂原子与硼原子络合以提高互变异构酮类共振形式的机会。该策略显着红移了 HBT 的发射波长，大大提高了其量子产率，并且对分子大小几乎没有影响。通常，化合物12B 和 13B 观察到在近红外区域发射，使它们成为最小的有机结构之一，发射高于 650 nm。