Mercury is a highly toxic and hazardous environmental contaminant, even at low levels. Excessive exposure of the human body to mercury leads to DNA damage, brain damage, and nervous system defects, including Minamata disease. The design and synthesis of fluorescent sensors for mercury ions has recently become attractive for developing chemical detectors that offer high selectivity and sensitivity. In the present study, three novel macromolecules, 1, 2 and 3, were prepared as fluoroionophores for the selective optical detection of Hg2+in aqueousorganic solutions. Compound 1 based on 2-(3-(2-aminoethylthio)propylthio)ethanamine covalently bound to two units of 7-nitrobenzo-2-oxa-1,3-diazolyl fluorophores. Compound 2 consists of 2-(3-(2-aminoethylthio)propylthio)ethanamine covalently bound to two units of dansyl moieties. Compound 3 based on 2-(4-(2-aminoethylthio)butylthio)ethanamine possessing two dansyl moieties. The compounds were readily obtained by the ready synthetic approach from a conventional two-step synthesis and are based on a flexible pendant structure containing two sulfur atoms and two nitrogen atoms which are covalently bound to two NBD or dansyl fluorophores. The ion binding takes place by a favorable electrostatic interactions between the sulfur and nitrogen atoms of the ligand and Hg2+ and is resulted in the fluorescence quenching. Sensors exhibit Hg2+ selective ON-OFF fluorescence quenching behavior in aqueous acetonitrile solutions and are shown to discriminate various foreign ions such as Cu2+, Ag+, Zn2+, Cd2+, Co2+, Ca2+, Na+ and Fe 3+. In acetonitrile/water solvent mixtures, 1, 2 and 3 act as ON-OFF fluorescence switches upon Hg2+ binding, exhibiting detection limits of 20, 1.4 and 50 ppb, respectively. The detection limits of these sensors are sufficient for the detection of submicromolar concentration ranges of Hg2+ ions found in the environment and many biological systems. Compound 4 was prepared for utilizing as a surface-based sensor. Self-assembled monolayer (SAM) of compound 4 was prepared and deposited on a quartz surface. Characterization of quartz surface modified with 4 was carried out by sessile drop contact angle goniometry. The cation recognition properties of the SAMs were attempted to study by fluorescence spectroscopy. Unfortunately, the fluorescence signals of the SAMs on a quartz surface could not be successfully determined