This project aims to develop multifunctional optical probes based on nitrogen heterocyclic systems capable of sensitive and selective detection of both pH changes and biologically relevant metal ions. Building on our previous work on benzazole-based pH sensors, the central concept is to extend these platforms toward integrated sensing, where protonation and metal coordination are combined within a single molecular framework. Such systems are expected to offer enhanced analytical performance and multi-parameter responsiveness, addressing limitations of conventional single-analyte probes. This approach is particularly relevant because metal ion speciation and binding are strongly pH-dependent, and their simultaneous detection enables more accurate analysis of complex chemical environments.The research will focus on the molecular engineering of benzazole and related heterocycles, incorporating systematically varied donor-acceptor substituents and tailored coordination sites to tune optical and binding properties. The prepared compounds will be evaluated with UV–Vis and fluorescence spectroscopy to determine pH responsiveness, emission behaviour, sensitivity, and selectivity toward target metal cations. In parallel, mass spectrometry (ESI-MS and MS/MS) will be used to elucidate binding stoichiometry, complex stability, and interaction mechanisms, providing complementary structural insight.Computational studies will employ density functional theory, molecular dynamics simulations, and ONIOM QM/MM approaches to investigate protonation equilibria, coordination modes, and electronic transitions, supporting the development of predictive structure-property relationships.The expected outcomes include new multifunctional optical sensors, validated methodologies, and general design principles. The project advances chemical sensing toward integrated, tuneable molecular probes with applications in environmental monitoring, analytical chemistry, and biologically relevant systems.