Two novel spirobifluorene-based two-photon fluorescent probes for the detection of hydrazine in solution and living cells

Two spirobifluorene-based two-photon fluorescent probes for the detection of hydrazine, namely SPF-MN and SPF- PA, have been designed and synthesized. Along with the addition of hydrazine to a solution of SPF-MN, both a colorimetric change from yellow to colorless and a fluorescence change from yellow to blue (Under 365 nm UV light) can be observed by ‘‘naked-eye’’. Probe SPF- PA displayed response toward hydrazine with fluorescence enhancement. The detection limits are 6.9 μM for SPF- PA and 0.29 μM for SPF-MN, respectively. Moreover, SPF-MN and SPF- PA can be used as two-photon fluorescent probes for hydrazine with large two-photon absorption cross-sections and used for the imaging of hydrazine in living cells. Specially, SPF-PA can located at the surface of the cells, and it is the first fluorescent probe which possesses the capability of sensing intercellular hydrazine. Besides, SPF-MN is the first colorimetric two-photon fluorescent probe for meeting the criteria of both hydrazine bioimaging and visual detection of hydrazine in solution.