Light‐Regulated Nucleation for Growing Highly Uniform Single‐Crystalline Microrods.

We report a light‐irradiation method to control the synchronous nucleation of a donor‐acceptor (D‐A) fluorophore for growing highly uniform single‐crystalline microrods, which is in sharp contrast to the prevailing methods of restricting spontaneous nucleation and additionally adding seeds. The D‐A fluorophore was observed to undergo photoinduced electron transfer to CrCl3, leading to the generation of HCl and the subsequent protonation of the D‐A fluorophore. By intensifying photoirradiation or prolonging its duration, the concentration of protonated D‐A fluorophores can be rapidly increased to a high supersaturation level. This results in the formation of a controlled number of nuclei in a synchronous manner, which in turn kickstart the epitaxial growth of protonated D‐A fluorophores towards uniform single‐crystalline microrods of controlled sizes. The light‐regulated synchronous nucleation and uniform growth of microrods are a unique phenomenon that can only be achieved by specific Lewis acids, making it a novel probing method for sensitively detecting strong Lewis acids such as chromium chloride. [ABSTRACT FROM AUTHOR]