Perylene DiimideBased Fluorescent and Colorimetric Sensors for Environmental Detection Perylene tetracarboxylic diimide (PDI) and its derivatives exhibit excellent thermal, chemical and optical stability, strong electron affinity, strong visiblelight absorption and unique fluorescence onoff features. The combination of these features makes PDIs ideal molecular frameworks for development in a broad range of sensors for detecting environmental pollutants such as heavy metal ions (e.g., Cu2, Cd2, Hg2, Pd2, etc.), inorganic anions (e.g., Fxe2x88x92, ClO4xe2x88x92, PO4xe2x88x92, etc.), as well as poisonous organic compounds such as nitriles, amines, nitroaromatics, benzene homologues, etc. In this review, we provide a comprehensive overview of the recent advance in research and development of PDIbased fluorescent sensors, as well as related colorimetric and multimode sensor systems, for environmental detection in aqueous, organic or mixed solutions. The molecular design of PDIs and structural optimization of the sensor system (regarding both sensitivity and selectivity) in response to varying analytes are discussed in detail. At the end, a perspective summary is provided covering both the key challenges and potential solutions for the future development of PDIbased optical sensors.

Molecular Dissection of dH3w, A Fluorescent Peptidyl Sensor for Zinc and Mercury Previously, we reported that fluorescent peptide dansylHPHGHWNH2 (dH3w), designed on the repeats of the human histidinerich glycoprotein, shows a turnon response to Zn(II) and a complex response to Hg(II) characterized by a turnoff phase at low Hg(II) concentrations and a turnon phase at high concentrations. As Hg(II) easily displaces Zn(II), dH3w is a useful probe for the environmental monitoring of Hg(II). In order to investigate the molecular basis of the metal selectivity and fluorescence response, we characterized three variants, dH3w(H1A), dH3w(H3A), and dH3w(H5A), in which each of the three histidine residues was changed to alanine, and two variants with a single fluorescent moiety, namely dH3w(W6A), in which the tryptophan residue at the Cterminus was changed to alanine, and AcH3w, in which the Nterminal dansyl moiety was substituted by an acetyl group. These variants allowed us to demonstrate that all the histidine residues are essential for a strong interaction with Zn(II), whereas two histidine residues (in particular His5) and the dansyl group are necessary to bind Hg(II). The data reported herein shed light on the molecular behavior of dH3w, thus paving the way to the rational designing of further and more efficient fluorescent peptidyl probes for Hg(II).