Fluorescence microscopy offers the opportunity to image noninvasively biological samples in real time. However, the phenomenon of diffraction limits the resolution of conventional fluorescence microscopes to submicrometer dimensions in both the horizontal and vertical directions. This limitation can be overcome by photoswitchable fluorescent probes able to undergo reversible saturable optically linear fluorescence transitions (RESOLFT).

In this study, firstly, a photoswitchable fluorescent probe based on BODIPY fluorophore and Spiropyran photochrome were designed and its photophysical and photochemical properties were investigated in organic and aqueous environments. Also, its imaging with patterned illumination was showed by trapping them in PMMA matrix.

Secondly, photochromic [1,3]oxazines with different substituents as well as polymers incorporating them were synthesized and their photochemical and photophysical properties were investigated.

Thirdly, to improve the switching speeds and fatigue resistance of the BODIPY-Spiropyran conjugate, the photochromic part was replaced by [1,3]oxazines and dyads incorporating BODIPY fluorophore and [1,3]oxazine photochromes were synthesized.

Lastly, a new strategy was designed to switch the fluorescence of fluorophores by a modular approach. It is based on photoinduced elongation of the absorption wavelength of a fluorescent chromophore with the aid of an appended photochromic auxochrome.