Riccardo Sinisi

Easy Separation of Δ and Λ Isomers of Highly Luminescent [IrIII]‐Cyclometalated Complexes Based on Chiral Phenol‐Oxazoline Ancillary Ligands

A new class of neutral cyclometalated iridium(III) complexes with enantiomerically pure C(1)-symmetric phenol-oxazolines (3a,b) have been synthetized in high yields and fully characterized. Resolution of the corresponding Δ(R) and Λ(R) or Δ(S) and Λ(S) isomers was easily achieved by conventional flash chromatography. The corresponding Δ and Λ helicities have been confirmed by CD spectroscopy and X-ray crystallography. Regarding the absorption and luminescence properties with unpolarized light, no significant difference between Δ and Λ isomers has been observed. A strong blue luminescence is observed for deaerated solutions of complexes 5a and 5b in CH(3)CN.

Efficient guanidine-catalyzed alkylation of indoles with fluoromethyl ketones in the presence of water.

A simple and efficient guanidine-catalyzed methodology for the direct preparation of trifluoromethyl-indolyl-phenylethanols in the presence of water is reported. This synthetically viable class of compounds is obtained in excellent yields (up to 98%) through Friedel-Crafts-type alkylation of indoles with aromatic fluoromethyl ketones. Exceptional reaction scope of indoles and alkylating agents is described.

New Polyphenolic β-Lactams with Antioxidant Activity

Novel 4‐alkylidene‐β‐lactams with a polyphenolic side chain were synthesized and evaluated as radical scavengers. We have undertaken a detailed study of the antioxidant activity in vitro with chemical and biological testing of the new β‐lactams and of the corresponding methyl polyhydroxy benzoates. Antioxidant activity of β‐lactams and methyl benzoates was measured with the Briggs–Rauscher oscillating reaction, the TEAC (Trolox® Equivalent Antioxidant Capacity) assay, and as ability to inhibit ROS (=Reactive Oxygen Species) production on myoblast H9c2 cells. The results were discussed with regard to mechanism and correlated with structural parameters.

Blue and highly emitting [Ir(IV)] complexes by an efficient photoreaction of yellow luminescent [Ir(III)] complexes

A family of cyclometalated [Ir(III)] complexes containing two F2ppy ligands and a bis-oxazoline (box) ancillary ligand, either chiral (1) or achiral (2) has been synthesized. They exhibit photophysical and electrochemical properties quite similar to the isoelectronic and well known [Ir(F2ppy)2(acac)] complex. However, an unprecedented photoreactivity has been observed. Upon UV irradiation of air-equilibrated solutions of both complexes, stable photoproducts containing an [Ir(IV)] metal center are obtained. The photoproducts exhibit highly efficient blue luminescence with good OLED performances. The same [Ir(IV)] complexes are obtained also by electrochemical oxidation.