A heterodimeric polyaminocarboxylate ligand based on a DO3A-sulfonamide linked to AAZTA (6-amino-6-methylperhydro-1,4-diazepinetetracarboxylic acid) was synthesised via an orthogonal pathway in order to differentiate the two chelating cages and allow the formation of a Gd(III)-Ga(III) heteroditopic complex. The goal is to create a smart MRI/PET probe with pH dependent relaxivity and with the bimodal imaging approach that enables direct quantification of the stimulus, in this case pH. A (1)H NMR relaxometric study of the Gd-Ga heteroditopic complex addressed the pH modulation of the relaxivity and thus its possible use as an MRI pH sensitive probe.

Hexasubstituted hybrid tetradentate (N,N′,P,P′)-ferrocenes bearing phosphino and aminomethyl groups, plus hindering tert-butyl moieties, were synthesized by using two different strategies: a "diverging" synthesis involving successive functionalization of preformed di-tert-butylated ferrocene and a "converging" assembly of the species from appropriately substituted cyclopentadienyl rings. While the new cyclopentadienyl salts formed are of interest, their assembly with iron dichloride used as a "converging" way to produce tetradentate ferrocene ligands presented several drawbacks. Conversely, the synthesis of new tert-butylated (aminomethyl)ferrocene derivatives was found convenient to further form (N,N′)-aminomethyl,(P,P′)-tert-butylated-ferrocenyl diphosphines by N-directed ortho-metalation. The novel N 2didentate and N 2 P 2 -tetradentate tert-butylated ferrocene compounds were all synthesized in good to high yields (48−96%) and tolerated aryl, alkyl, and heteroaryl phosphino groups as substituents on nitrogen and phosphorus atoms. They were characterized by X-ray diffraction and multinuclear NMR ( 1 H, 13 C, 31 P, 15 N). We observed the conformation control provided to rac-(N,N′)-diaminomethyl-(P,P′)-tert-butylated-ferrocenyldiphosphines with in particular the systematic near-eclipsed conformation of aminomethyl groups. This conformation is at the origin of the unexpected formation at RT of a zwitterionic cyclopalladate from an (aminomethyl)ferrocene derivative, arising from intramolecular Cp-proton transfer to the proximate free amino group by simple C−H activation reaction in the presence of palladium dichloride.

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Several prochiral NCN pincer complexes of palladium(II) including hemilabile ligands and a long aliphatic chain were synthesized and characterized spectroscopically. In some of the complexes, the presence of two different substituents on the N donor atoms made them stereogenic so that they were isolated as a mixture of diastereoisomers, which could be differentiated by 1 H NMR. Binding of some of these complexes to bovine b-lactoglobin by insertion within its inner cavity was theoretically investigated by molecular docking simulations and experimentally confirmed by CD spectroscopy.Adjunction of H-bond donor substituents on the ligand framework gave more stable supramolecular protein -complex assemblies. These constructs were shown to catalyze aldol condensation reactions in aqueous medium affording in some cases the less favorable cis-product. Since the corresponding complexes gave exclusively the trans product in the absence of b-lactoglobulin, this unusual diastereoselectivity was ensued by the second sphere of coordination brought by the protein host.2