Cyanide (CN
–
) is an anion well–known for its toxicity, being a chemical
agent often related to cases of homicide and suicide. Despite being responsible for the
toxicity of many animals and plants, it is used in several industrial activities, with
innumerous implications in terms of the environment. Due to its high toxicity, the
maximum level of CN
–
concentration allowed by the World Health Organization in potable
water is 1.7 µmol/L. This low concentration limit requires methods of visual detection and
quantitative determination which are ever more sensitive, simple, reliable, and
economical. Advancements in the field of chromogenic and fluorogenic chemosensors for
anionic analytes have led to the development of several methodologies for the detection
of CN
–
. Therefore, this review aims to present the main strategies that have been used in
the study of quantitative and naked–eye detection of CN
–
by means of chromogenic and
fluorogenic chemosensors. Aspects related to CN
–
, such as its reactivity, toxicity,
applications, and implications in different domains of knowledge, are presented. Recent
work involving the development of chemosensors for CN
–
based on acid–base reactions,
chemodosimeters, chromoreactands, and competition assays is also described. In
addition, recent studies that make use of nanotechnology to develop strategies for the
detection of CN
–
are also discussed, as well as the prospects envisioned in this field.
