Due to ever-increasing insights into their fundamental
properties
and photochromic behaviors, spiropyran derivatives are still a target
of interest for researchers. The interswitching ability of this photochrome
between the spiropyran (SP) and merocyanine (MC) isoforms under external
stimuli (light, cations, anions, pH etc.) with different spectral
properties as well as the protonation–deprotonation of its
MC form allows researchers to use it suitably in sensing purposes
by developing different colorimetric and fluorometric probes. Selective
and sensitive recognition can be achieved by little modification of
its SP moiety and functional groups. In this review, we emphasize
the recent advancements (from 2019 to 2022) of spiropyran–merocyanine
based fluorogenic and chromogenic probes for selective detection of
various metal ions, anions, neutral analytes, and pH. We precisely
explain their design strategies, sensing mechanisms, and biological
and environmental applications. This review may accelerate the improvements
in designing more advanced probes with innovative applications in
the near future.