Sensitized terbium(III) macrocyclic-phthalimide complexes as luminescent pH switches.

Four new macrocyclic-phthalimide ligands were synthesised via the coupling of N-(3-bromopropyl)phthalimide either to cyclen (1,4,7,10-tetraazacyclododecane) itself or its carboxylate-functionalized analogues, and photophysical studies were carried out on their corresponding Tb(III) complexes in aqueous media as a function of pH. Luminescence intensities of Tb·L1a–Tb·L3a were in ‘switched off’ mode under acidic conditions (pH < 4), and were activated on progression to basic conditions as the phthalimido functions therein were hydrolysed to their corresponding phthalamates Tb·L1b–Tb·L3b. Emission of phthalamate-based macrocyclic Tb(III) complexes Tb·L1b–Tb·L3b was in ‘switched on’ mode between pH 4 and 11, exhibiting high quantum yields (Φ) and long lifetimes (τ) of the order of milliseconds at pH ~ 6.

A chemically unlocked binary molecular switch.

A highly luminescent and sensitive terbium complex of a ligand comprising of a phthalimide group appended to a DO3A moiety is an active pH sensor that is conditional on its previous pH.

¹H NMR study of monocrotaline and its metabolites in human blood.

Monocrotaline (MCT) is a naturally occurring hepatotoxic pyrrolizidine alkaloid found in plants. This investigation is aimed at furthering the understanding of the role of blood in mediating the transport of MCT and its reactive metabolites in humans. Reactions of monocrotaline and its metabolites, dehydromonocrotaline (DHM), retronecine (RET) and dehydroretronecine (DHR) with human blood plasma, red blood cells (RBCs), and whole blood were studied in vitro by proton nuclear magnetic resonance spectroscopy.

Synthesis and characterisation of a novel tubulin-directed DO3A-colchicine conjugate with potential theranostic features.

Colchicine is a known tubulin binding agent enabling necrosis in tumors. A novel tubulin-directed DO3A-colchicine conjugate and its Gd(III) complex were prepared from N-deacetylcolchicine, coupling alkaloid and polyaza-alicyclic functions via a peptide coupling methodology. The longitudinal proton relaxivity of the Gd(III) complex in water at 4.