Luminescent Chemosensors: From Molecules to Nanostructures

Abstract

Chemical analysis has been improved by the advent of sensory devices based on chemosensors that are able to transform chemical information (composition, concentration, etc.) into an analytically useful signal. These devices, in fact, find applications in many different areas of great social and economic impact. Among all the possible chemosensors, we focus here our attention on luminescent ones as they present many advantages such as sensitiveness, low cost, ease of use and versatility. After a discussion on their pros and cons and of the most important features in the design of new species with customized properties, we present selected examples of different chemosensors that take advantage from various transduction mechanisms always following a supramolecular approach. A step forward in the research and application has been done implementing these structures in nanosized materials to obtain powerful and versatile platforms for addressing crucial issues in sensing, imaging, and molecular testing. In this context we have chosen to restrict the discus-sion on luminescent multichromophoric silica-based nanoprobes as a virtuous exam-ple of how a high design versatility allows the preparation of nanostructures where modulation and multifunctionality offer the possibility to induce collective energy-and electron-transfer processes, that are at the base of signal amplification effects. 12.1 Introduction The sensing process, in a general acceptation, exploits one or more chemical-physical phenomena to inform about the external environment (sensing domain), and converts the stimulus of the sensed phenomenon/species into a signal or data stream that can be understood and manipulate. To obtain the detection of the target analyte, therefore, two different processes are needed: molecular recognition and signal transduction. This means that the starting point is always the design of single molecules, or of arrays of molecules,