title: Lanthanide clusters with chalcogen encapsulated Ln: NIR emission from nanoscale NdSe(x).
abstract: Ln(SePh)(3) (Ln = Ce, Pr, Nd) reacts with elemental Se in the presence of Na ions to give (py)(16)Ln(17)NaSe(18)(SePh)(16), a spherical cluster with a 1 nm diameter. All three rare-earth metals form isostructural products. The molecular structure contains a central Ln ion surrounded by eight five-coordinate Se(2-) that are then surrounded by a group of 16 Ln that define the cluster surface, with additional μ(3) and μ(5) Se(2-), μ(3) and μ(4) SePh(-), and pyridine donors saturating the vacant coordination sites of the surface Ln, and a Na ion coordinating to selenolates, a selenido, and pyridine ligands. NIR emission studies of the Nd compound reveal that this material has a 35% quantum efficiency, with four transitions from the excited state (4)F(3/2) ion to (4)I(9/2), (4)I(11/2), (4)I(13/2), and (4)I(15/2) states clearly evident. The presence of Na(+) is key to the formation of these larger clusters, where reactions using identical concentrations of Nd(SePh)(3) and Se with either Li or K led only to the isolation of (py)(8)Nd(8)Se(6)(SePh)(12).
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway New Jersey 08854-8087, United States.
authors.forename: Brian F
authors.initials: BF
authors.lastname: Moore
authors.forename: G Ajith
authors.initials: GA
authors.lastname: Kumar
authors.forename: Mei-Chee
authors.initials: MC
authors.lastname: Tan
authors.forename: Jesse
authors.initials: J
authors.lastname: Kohl
authors.forename: Richard E
authors.initials: RE
authors.lastname: Riman
authors.forename: Mikhail G
authors.initials: MG
authors.lastname: Brik
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Emge
authors.forename: John G
authors.initials: JG
authors.lastname: Brennan