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A novel butterfly-shaped tetracarboxylic acid [9,9′-methylene-bis(9-methylfluorene-2,7-dicarboxylic acid), H4L] featuring a co-facial bifluorene core was designed and synthesised. Reactions of H4L with CdII produced the luminescent supramolecular frameworks 2 and 3, with different dimensionalities and wingspans of L4−. Their solid-state emission properties were rationalised based on the torsional dynamics of the facing bifluorene units by means of X-ray diffraction analysis and TD-DFT calculations.

The H-shaped [I10Cl4]4− polyhalide is the result of the interplay of directional HBs, XBs and π–π interactions driven by the structural features of the 2-(p-tolyl)selenopheno[2,3-b]pyridinium cation template.

The reaction between differently substituted borasiloxanes and 2,5-bis(3-pyridylethynyl)thiophene provided the first example of luminescent borasiloxane-based chiral helices held together by N-B bonds. The starting building blocks and the helices were fully characterized, and the nature of the N-B bond rationalized by means of theoretical calculations.

Five coumarin derivatives, able to coordinate Fe(III) and exhibit a ratiometric and turn-on fluorescence response, were prepared and tested. The derivative with the –OCH3 substituent exhibited a high fluorescence enhancement in the presence of Fe(III), Ga(III), Au(III) and Y(III). Thanks to the higher stability of the Fe(III) complexes, this molecule could be proposed as a selective fluorescent sensor for the detection of Fe(III) in CH3CN and CH3CN : H2O (1 : 1, v/v) solutions, showing a linear response up to 35.0 μM Fe(III) concentration and a limit of detection of 2.4 μM Fe(III) concentration. The fluorescence response towards this ion was also tested on a solid surface with a simple cellulose paper-strip test. The peculiarity of the proposed sensor lies in its easy and low-cost synthesis, relevant ratiometric response and, since it is derived from a natural product, low impact on the environment and its organisms.

Sulphur and nitrogen oxide pollutants cause acid rain that can eventually lead to the dissolution of calcite in marble and limestones. Calcium oxalate is an inorganic protective agent, which is obtained by treatment with ammonium oxalate. The functionalization of oxalic acid to give monoesters and monoamides (oxamates) allows tailoring the solubility of the relevant ammonium and calcium salts. In this context, theoretical calculations carried out at the Density Functional Theory (DFT) level were exploited to investigate the capability of oxalate, methyloxalate, phenyloxalate, oxamate, methyloxamate, and phenyloxamate to interact with the calcium carbonate lattice. An in-depth validation based on the structural data showed that DFT calculations with the PBE0 functional along with a single or triple-zeta def2 basis set allow understanding the different reactivity of the oxalate and oxamate derivatives and their efficiency in interacting with stones containing calcium carbonate, such as Carrara marble and biomicritic limestones.

The synthesis of 5-hydroxy-2-(hydroxymethyl)pyridin-4(1H)-one (P1) is presented, together with the evaluation of its coordination ability towards Fe(3+), studied by a combination of chemical, computational, and animal approaches. The use of complementary analytical techniques has allowed us to give evidence of the tautomeric changes of P1 as a function of pH, and to determine their influence on the coordinating ability of P1 towards Fe(3+). The pFe(3+) value 22.0 of P1-iron complexes is noticeably higher than that of deferiprone (20.6), one of the three clinical chelating agents in therapeutic use for iron overload diseases. This is due on one side to the tautomeric change to the catechol form, and on the other to the lower protonation constant of the OH group. Bio-distribution studies on mice allowed us to confirm in vivo the efficacy of P1. Furthermore the coordinating ability toward Al(3+), Cu(2+) and Zn(2+) has been studied to evaluate the possible use of P1 against a second toxic metal ion (Al(3+)), and to envisage its potential influence on the homeostatic equilibria of essential metal ions. The chelating ability of P1 toward these ions, not higher than that of the corresponding deferiprone, contributes to render P1 a more selective iron chelator.

Five new [Pt(N^N)(dtoc)] complexes (1-5; N^N = diimine: 2,2'-bipyridine and its 4,4'-alkyl/aryl-substituted derivatives or 1,10-phenanthroline; dtoc(2-) = 1,2-dithiolate-1,2-closo-dicarbadodecaborane) have been synthesized and characterized by spectroscopic and electrochemical methods, and by means of X-ray diffraction in the case of complexes 1 and 4. Hybrid DFT and time-dependent (TD) DFT calculations were performed on complexes 1-5 and the previously reported complex [Pt(Ph2phen)(dtoc)] (6; Ph2phen = 4,7-diphenyl-1,10-phenanthroline) both in the gas phase and in the presence of several solvents (CH2Cl2, CHCl3, CH3CN, acetone, THF, DMF, DMSO, and toluene) to gain an insight into the electronic structure of the complexes and explain their experimental features. Theoretical calculations allowed for the determination of structure-property relationships within the series of the six complexes considered, and the prediction of their second order nonlinear optical (SONLO) properties by evaluating their first static hyperpolarizabilities (βtot).

Four new fluorescent chemosensors for metal ions based on 8-hydroxyquinoline (8-HDQ) derivatives and sulfur-containing macrocyclic units were synthesized and characterized, namely 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L1), 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L2), 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L3), and 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L4). Preliminary fluorimetric titrations indicated L1 as the only member of the family of ligands to give a selective CHEF-type response to the presence of Zn(2+) in MeCN-H2O (1:1, v/v) solutions, which allowed imaging of this metal ion in Cos-7 cells in vitro. The other ligands either did not show any fluorescence response (L3, L4) to any of the metal ions considered (Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+)) or gave (L2) a CHEF-type response also to the presence of Cd(2+). The coordination properties of L1 towards Zn(2+) were, therefore, fully investigated by potentiometric measurements and absorption and emission spectroscopy at different pH values, which indicated that the formation of 2:1 L1/Zn(2+) complexes is responsible for the CHEF-type effect observed. The complexes [Zn(L1)2H2O](BF4)2 and [Zn(L3)](ClO4)2 were characterized in the solid state by X-ray crystallography, and DFT calculations were performed to understand the origin of the Zn(2+)/Cd(2+) optical discrimination of the 8-HDQ-based "conjugate" fluorescent chemosensors reported.

The I(2)-adducts of drugs propylthiouracil (PTU) and methimazole (MeImSH) oxidize liquid mercury in dichloromethane to separate in good yield the neutral complexes [HgI(2)(PTU)(2)·MeOH] (1), [HgI(2)(PTU)(2)·HgI(2)] (2), and [Hg(2)I(4)(MeImSH)(2)] (3). The single crystal X-ray diffraction analysis of 1-2 shows that the Hg(II) center is coordinated by two sulfur atoms and by two iodine atoms in a tetrahedral geometry. In complex 2 almost linear molecules of HgI(2) result encapsulated in the crystal packing enfolded by the hydrophobic propyl appendages of coordinated units of PTU. X-ray analysis of complex 3 shows the presence of dimeric [Hg(2)I(4)(MeImSH)(2)] molecules to form Hg(2)S(2)I(4) cores. The intra- and intermolecular hydrogen bonds concerning PTU and MeImSH have been evaluated. The oxidation of Hg(0) to Hg(II) requires a two-electron transfer process accomplished by an oxidative addition from the "activated" iodine moiety. The oxidizing and complexing properties of PTU-I(2) and MeImSH-I(2) have been interpreted considering the S-donor to I(2) interaction that leads to a charge separation between the sulfur-bound iodine atom S-I and the terminal I atom. Compounds 1, 2, and 3 react with tetraethylammonium iodide to separate the compound (Et(4)N)(2)[HgI(4)] with the release of free PTU and MeImSH, respectively. The reported dissolution technique could be applied to the recovery of mercury from waste electrical and electronic equipment (WEEE) scrap, the nature of complexes 1-3 makes it possible the easy separation of the mercury as tetraiodomercurate anion and the recycling of the donors.