A Unique Family of Rigid Analogues of the GFP Chromophore with Tunable Two‐Photon Action Cross‐Sections for Biological Imaging

Conformationally restricted analogues of the GFP chromophore have been synthesized. The spectroscopic properties of GCTPOC, a unique family with tunable two-photon action cross-sections, were investigated. GCTPOC could be used as a robust two-photon platform for development of a two-photon fluorescent thiol sensor, which could stain endogenous thiols both in vitro and in vivo.