SolidState Emissive MetalloSupramolecular Assemblies of QuinolineBased Acyl Hydrazone Development of fluorescencebased sensory materials for metal elements is currently in the mainstream of research due to the simplicity and usability of fluorescence as a method of detection. Herein, we report a novel xe2x80x9cbisxe2x80x9dquinolinebased acyl hydrazonexe2x80x94named bQH that could be synthesized by a facile, lowcost method through simple condensation of hydrazide with an aldehyde. This acyl hydrazone showed emissive properties through Zn selective binding, especially in its solidstate, as shown by experiments such as UVxe2x80x93Vis, photoluminescence (PL), nuclear magnetic resonance (NMR), and inductivelycoupled plasmaoptical emission spectroscopies (ICPOES), and energydispersive Xray spectroscopy (EDS) mapping. The binding modes in which bQH coordinates to Zn2 was proved to consist of two modes, 1:1 and 1:2 (bQH:Zn2), where the binding mode was controlled by the Zn2 ion content. Under the 1:1 binding mode, bQHZn2 complexes formed a polymeric array through the metallosupramolecular assembly. The resulting bQHZn2 complex maintained its fluorescence in solidstate and exhibited excellent fluorescence intensity as compared to the previously reported quinolinebased acyl hydrazone derivative (mQH).

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).