title: NIR lanthanide luminescence by energy transfer from appended terpyridine-boradiazaindacene dyes.
abstract: Mononuclear trivalent lanthanide complexes with formula [Ln(L)(NO(3))(3)] [in which L=4,4-difluoro-8-(2':2'';6'':2'''-terpyridin-4''-yl)-1,3,5,7-tetramethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indacene (Boditerpy)] are reported for Ln=Yb, Nd, Er, La and Gd. According to the crystal structure of the Yb complex, the lanthanide ion is bound to the terdentate terpyridine and the inner coordination sphere of the nine-coordinate lanthanide ion is completed by three bidentate nitrate anions. The coordination polyhedron can be described as a distorted tricapped antiprism. The terpyridine chelate is almost planar and tilted by nearly 60 degrees from the indacene subunit. FT-IR spectra confirm the bidentate binding mode of the nitrate anions for the other complexes. NMR and ES-MS spectra (through characteristic isotopic patterns) confirm the chemical formulation. The complexes have high molar absorption coefficients in the visible spectral region (65,000 M(-1) cm(-1) at 529 nm) and display sizeable NIR luminescence (900 to 1600 nm, for Ln=Yb, Nd and Er), upon irradiation through the electronic state of the indacene moiety at 514 nm. Crystal-field splitting was analysed at low temperature. The quantum yield of the Yb solution (10(-4) M) in dichloromethane amounts to 0.31 %, corresponding to a sensitisation efficacy of the ligand of ca. 63 %.
authors.affiliation: Laboratoire de Chimie Moléculaire, Ecole de Chimie, Polymères, Matériaux, Université Louis Pasteur-CNRS, UMR 7509, 25 rue Becquerel, 67008 Strasbourg Cedex, France. ziessel@chimie.u-strasbg.fr
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Ziessel
authors.forename: Gilles
authors.initials: G
authors.lastname: Ulrich
authors.forename: Loïc
authors.initials: L
authors.lastname: Charbonnière
authors.forename: Daniel
authors.initials: D
authors.lastname: Imbert
authors.forename: Rosario
authors.initials: R
authors.lastname: Scopelliti
authors.forename: Jean-Claude G
authors.initials: JC
authors.lastname: Bünzli
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D000465:Algorithms; D001880:Boranes / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004396:Coloring Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004735:Energy Transfer; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy; D011725:Pyridines / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared
chemical_list: D001880:Boranes; D004396:Coloring Agents; D028581:Lanthanoid Series Elements; D008024:Ligands; D011725:Pyridines; C476083:boradiazaindacene; D015082:2,2'-Dipyridyl