Three luminescent tricarbonylrhenium(I) polypyridine complexes containing a tyramine-derived 2,2′-dipicolylamine (DPAT) unit, [Re(N∧N)(CO)3(py-TU-DPAT)](CF3SO3) (py-TU-DPAT = 3-(2-(4-hydroxy-3-(2,2′-dipicolylaminomethyl)phenyl)ethylthioureidyl)pyridine; N∧N = 1,10-phenanthroline (phen) (1a), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4-phen) (2a), 4,7-diphenyl-1,10-phenanthroline (Ph2-phen) (3a)), and their DPAT-free counterparts, [Re(N∧N)(CO)3(py-TU-Et)](CF3SO3) (py-TU-Et = 3-(ethylthioureidyl)pyridine; N∧N = phen (1b), Me4-phen (2b), Ph2-phen (3b)), have been synthesized and characterized. Their electrochemical and photophysical properties have been studied. Upon photoexcitation, all the complexes exhibited triplet metal-to-ligand charge-transfer (3MLCT) (dπ(Re) → π*(N∧N)) emission in fluid solutions at 298 K and in low-temperature alcohol glass. The DPAT complexes showed lower emission quantum yields and shorter emission lifetimes compared to those of the DPAT-free analogues, indicative of the quenching properties of the appended DPAT unit. The DPAT complexes also exhibited pH-dependent emission, with their emission intensities at pH < 3 being ca. 40 fold higher than those at pH > 11. These complexes displayed emission enhancement and lifetime elongation in the presence of zinc(II) and cadmium(II) ions. The cellular uptake of all the complexes by human cervix epithelioid carcinoma (HeLa) cells has been examined by ICP-MS. We have investigated the cytotoxicity of the complexes by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the results revealed that all the complexes were more cytotoxic than cisplatin. Furthermore, the cellular uptake of complexes 3a and 3b and the intracellular ion-binding properties of the former complex have been studied by laser-scanning confocal microscopy.

Glowing sweets! Three luminescent rhenium(I) polypyridine complexes have been modified with an α‐D‐glucose moiety. Their biomolecular binding, bacterial staining, and cellular‐uptake properties have been examined (see figure). Various experimental results have indicated that glucose transporters play a very important role in the cellular uptake of these glucose complexes.

Two novel luminescent polypyridinerhenium(I) bis-biotin com-(2)} and their biotinfree counterpart [N ∧ N = 4,4Ј-bis(n-butylaminocarbonyl)-2,2Ј-bipyridine, bpyC4 (3)] have been synthesized and characterized. Upon irradiation, all the complexes exhibited triplet metal-to-ligand charge-transfer ( 3 MLCT) emission in fluid solutions at room temperature and alcohol glass at 77 K. The avidin-binding properties of the bis-biotin complexes 1 and 2 have been studied by 4Ј-hydroxyazobenzene-2-carboxylic