Two neutral pyrazolato diimine rhenium(I) carbonyl complexes with formula [Re(CO)3(N-N)(btpz)] where N-N = 2,2‘-bipyridine (1) and 1,10-phenanathroline (2), and btpz = 3,5-bis(trifluoromethyl) pyrazolate, were synthesized and characterized by elemental analysis, routine spectroscopic methods, and single-crystal X-ray diffraction study. Ground and excited state properties of these complexes were investigated by steady-state and time-resolved spectroscopies. Complexes 1 and 2 show photoluminescent emission in both solution and solid-state at room temperature, arising from metal to ligand charge-transfer (MLCT) transition with strong overlapping of intraligand π → π* transitions. The long-lived excited state lifetimes of complexes 1 and 2, which are on the order of microseconds, indicate the presence of phosphorescent emission. As these complexes hold the potential to serve as phosphors for organic light-emitting diodes (OLEDs), their electroluminescent performances were evaluated by employing them as dopant...

Realizing Green Phosphorescent Light-Emitting Materials from Rhenium(I) Pyrazolato Diimine Complexes

Excited-state equilibration: a process leading to long-lived metal-to-ligand charge transfer luminescence in supramolecular systems

We report here the design of the first class of luminescent biotinylation reagents derived from rhenium(I) polypyridine complexes. These complexes [Re(N−N)(CO)3(py-biotin-NCS)](PF6) (py-biotin-NCS = 3-isothiocyanato-5-(N-((2-biotinamido)ethyl)aminocarbonyl)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)), containing a biotin unit and an isothiocyanate moiety, have been synthesized from the precursor amine complexes [Re(N−N)(CO)3(py-biotin-NH2)](PF6) (py-biotin-NH2 = 3-amino-5-(N-((2-biotinamido)ethyl)aminocarbonyl)pyridine; N−N = phen (1c), Me4-phen (2c), Ph2-phen (3c)). To investigate the amine-specific reactivity of the isothiocyanate complexes 1a−3a, they have been reacted with a model substrate ethylamine, resulting in the formation of the thiourea complexes [Re(N−N)(CO)3(py-biotin-TU-Et)](PF6) (py-biotin-TU-Et = 3-ethylthioureidyl-5-(N-((2-biotinamido)ethyl)aminocarbonyl)pyridine; N−N = phen (1b...

Rhenium(I) polypyridine biotin isothiocyanate complexes as the first luminescent biotinylation reagents: synthesis, photophysical properties, biological labeling, cytotoxicity, and imaging studies.

The synthesis, characterization, and X-ray crystal structures of [Re(diimine)(CO)3(dpe)](PF6) (dpe = 1,2-di(4-pyridyl)ethylene) compounds are reported. The cis-dpe complexes exhibit yellow luminescence after UV excitation, whereas the trans-dpe counterparts are nonluminescent. The luminescence quantum yields of the cis-dpe complexes are strongly dependent on the identity of the diimine ligand. Irradiation (350 nm) of the trans-dpe complexes induces trans → cis dpe-ligand isomerization with quantum yields on the order of 0.2, and this process leads to an on-switching of yellow luminescence. After long 350-nm irradiation times, a steady state composed of roughly 70% cis- and 30% trans-dpe complexes is reached. The reverse cis → trans photoisomerization reaction is induced by irradiating the cis-dpe complexes at 250 nm, switching off the yellow luminescence. For 250-nm excitation, photodecomposition of the [Re(diimine)(CO)3(dpe)]+ complexes competes efficiently with photoisomerization.

Photoswitchable luminescence of rhenium(i) tricarbonyl diimines.

Two novel diimine rhenium(I) carbonyl complexes with the formula [Re(CO)3(L)Br], where L = 1-(4-5‘-phenyl-1,3,4-oxadiazolylbenzyl)-2-pyridinylbenzoimidazole (1) and 1-(4-carbazolylbutyl)-2-pyridinylbenzoimidazole (2), have been successfully synthesized and characterized by elemental analysis, 1H NMR, and IR spectra. Their electrochemical, photophysical, and electroluminescent behaviors, along with the X-ray crystal structure analysis of 2, are also described. White electrophosphorescent devices were fabricated using 1 and 2 as emitters. The devices based on carbazole-containing (hole-transporting group) 2 with the structure ITO/m-MTDATA (30 nm)/NPB (20 nm)/2:CBP (8%, 30 nm)/Bphen (20 nm)/Alq3 (20 nm)/LiF (0.8 nm)/Al (200 nm) exhibit Commission Internationale de L'Eclairage coordinates of x = 0.34, y = 0.33 with a maximum brightness of 2300 cd/m2 at 580 mA/cm2. When a brightness of 1500 cd/m2 appears at 230 mA/cm2, the devices based on 10 wt % 2 still possess 56% of the maximum efficiency which appeared at...

Synthesis, structural characterization, and electrophosphorescent properties of rhenium(I) complexes containing carrier-transporting groups.

Photochemical and photophysical reactions of fac-rhenium(I) tricarbonyl complexes. Effects from binucleating spectator ligands on excited and ground state processes

Inhibition of the fac -(RCO2)ReI(CO3)(bis -azine) photodecarboxylation of the carboxylate ligand, RCO2- , when R is a strongly electron donating group : Thermal and photochemical properties of complexes where R = ferrocene, 4-(dimethylamino)benzyl

J. Guerrero

Papers

Photochemical and photophysical reactions of fac-rhenium(I) tricarbonyl complexes. Effects from binucleating spectator ligands on excited and ground state processes

Inhibition of the fac -(RCO2)ReI(CO3)(bis -azine) photodecarboxylation of the carboxylate ligand, RCO2- , when R is a strongly electron donating group : Thermal and photochemical properties of complexes where R = ferrocene, 4-(dimethylamino)benzyl