Trivalent analytes such as Fe³⁺, Cr³⁺ and A^l3+ play pivotal roles in various fields including environmental monitoring, biological sensing, and industrial processes. The development of efficient and selective detection methods for trivalent species is therefore of paramount importance. In this review, we present an overview of recent advances in the recognition of trivalent analytes using simple organic chromogenic and fluorogenic probes. In this review we discuss the strategies employed for the design and synthesis of chromogenic and fluorogenic probes tailored for trivalent analytes, highlighting key structural motifs and functional groups that contribute to their recognition capabilities.

A new salicylaldehyde-based sensor N'-(5-bromo-2-hydroxybenzylidene)-4-methylbenzohydrazide (P4) was designed, and its sensing ability towards various metal ions was assessed using UV-visible spectroscopy. The structure of P4 was spectroscopically characterized by UV-Visible, Infrared, ¹H-NMR, ¹³C-NMR spectroscopy and mass spectrometry. UV-Visible absorption spectral study showed selective sensing ability of P4 for Cd²⁺ and Ni²⁺ ions in presence of diverse transition metal ions. The results revealed that the detection limit for Cd²⁺ and Ni²⁺ was 3.14 µM and 0.92 µM, respectively. Moreover, the compound P4 was fully implemented for detection of Cd²⁺ and Ni²⁺ in simulated samples.