Studies on synthesis and evaluations of novel ratiometric fluorescent chemosensors based on pyrenes

Brief introductory outlines of present thesis are discussed in which the general introduction of fluorescent sensors based on pyrene and pyrene derivatives for ions are presented. Result and Discussion: Fluorescence spectroscopy which has been applied to single molecule detection is widely used because of its high sensitivity, facile operation, and low cost. The design of fluorescent sensors for heavy metals such as Zn 2+ , Cu 2+ , Fe 3+ , Cd 2+ , Hg 2+ is of particular importance, in part because of metals hazards and toxicity in biological, industrial and agricultural applications. Moreover, anion binding is now a major research endeavor. Anions are ubiquitous in nature and play important roles in nature and in biological and chemical systems. Whether one is designing a molecular sensor for the detection of a cation, an anion or both simultaneously, the hosts design rquires the same criterion, i.e. a binding site, a reporter group and molecular scaffold. Furthermore, the photophysical properties of a fluorophore can be easily tuned using a range of mechanisms. These mechanisms include intramolecular charge transfer (ICT), photoinduced electron transfer (PET), the influence of the heavy metal ions (heavy atom effect), and metal-to-ligand charge transfer (MLCT), chelation enhanced quenching (CHEQ) and Forster (coulombic) resonance energy transfer (FRET) are utilized in sensing. The fluorophore can be in the form of organic dyes, luminescent metal complexes. One such fluorophore that has been extensively studied and the photophysics is well understood, is that of the pyrene motif. Pyrene is one of the classical polycyclic aromatic hydrocarbons (PAHs), which shows a high fluoresence (FL) quantum yield in solution and efficient excimer formation. Conclusion: According to the above review of recent development of chemosensor for cations and anions based on pyrene, the synthesis, characterization, and ions selectivity recognition properties of receptor focused on pyrene would exhibit further interests and challenges to the supramolecular chemists. Reference: (1) E. Manandhar, K. J. Wallace, Onorg. Chim. Acta. 381 (2012) 15;(2) J.R. Lakowicz, Ed. Principles of Fluorescence Spectroscopy; Plenum Publishers Corp.: New York, 1999.