Performance of Spherical Quantum Well Down Converters in Solid State Lighting.

We report the color conversion performance of amber and red emitting quantum dots (QDs) on InGaN solid-state lighting (SSL) light emitting diode (LED) packages. Spherical quantum well (SQW) architectures (CdS/CdSeS/CdS) were prepared using a library of thio- and selenourea synthesis reagents and high throughput synthesis robotics. CdS/CdSeS QDs with narrow luminescence bands were coated with thick CdS shells (thickness = 1.

Multiplexed SNP genotyping using the Qbead system: a quantum dot-encoded microsphere-based assay.

We have developed a new method using the Qbead system for high-throughput genotyping of single nucleotide polymorphisms (SNPs). The Qbead system employs fluorescent Qdot semiconductor nanocrystals, also known as quantum dots, to encode microspheres that subsequently can be used as a platform for multiplexed assays. By combining mixtures of quantum dots with distinct emission wavelengths and intensities, unique spectral 'barcodes' are created that enable the high levels of multiplexing required for complex genetic analyses.

Immunofluorescent labeling of cancer marker Her2 and other cellular targets with semiconductor quantum dots.

Semiconductor quantum dots (QDs) are among the most promising emerging fluorescent labels for cellular imaging. However, it is unclear whether QDs, which are nanoparticles rather than small molecules, can specifically and effectively label molecular targets at a subcellular level. Here we have used QDs linked to immunoglobulin G (IgG) and streptavidin to label the breast cancer marker Her2 on the surface of fixed and live cancer cells, to stain actin and microtubule fibers in the cytoplasm, and to detect nuclear antigens inside the nucleus.

A New Electron-Transfer Donor for Photoinduced Electron Transfer in Polypyridyl Molecular Assemblies.

A synthetic procedure has been devised for the preparation of the reductive quencher ligand 4-methyl-4'-(N-methyl-p-tolylaminomethyl)-2,2'-bipyridine (dmb-tol), which contains toluidine covalently bound to 2,2'-bipyridine. When bound to Re(I) in [Re(I)(dmb-tol)(CO)(3)Cl], laser flash Re(I) --> dmb metal-to-ligand charge-transfer (MLCT) excitation at 355 nm in CH(3)CN at 298 +/- 2 K is followed by efficient, rapid (<5 ns) appearance of a transient with an absorption feature at 470 nm. The transient spectrum is consistent with formation of the redox-separated state, [Re(I)(dmb(-)-tol(+))(CO)(3)Cl], which returns to the ground state by back electron transfer with k(ET) = (1.

Excited-State Electronic Structure in Polypyridyl Complexes Containing Unsymmetrical Ligands.

Step-scan Fourier transform infrared absorption difference time-resolved (S(2)FTIR DeltaA TRS) and time-resolved resonance Raman (TR(3)) spectroscopies have been applied to a series of questions related to excited-state structure in the metal-to-ligand charge transfer (MLCT) excited states of [Ru(bpy)(2)(4,4'-(CO(2)Et)(2)bpy)](2+), [Ru(bpy)(2)(4-CO(2)Et-4'-CH(3)bpy)](2+), [Ru(bpy)(4,4'-(CO(2)Et)(2)bpy)(2)](2+), [Ru(4,4'-(CO(2)Et)(2)bpy)(3)](2+), [Ru(bpy)(2)(4,4'-(CONEt(2))(2)bpy)](2+), [Ru(bpy)(2)(4-CONEt(2)-4'-CH(3)bpy)](2+), and [Ru(4-CONEt(2)-4'-CH(3)bpy)(3)](2+) (bpy is 2,2'-bipyridine). These complexes contain bpy ligands which are either symmetrically or unsymmetrically derivatized with electron-withdrawing ester or amide substituents. Analysis of the vibrational data, largely based on the magnitudes of the nu(CO) shifts of the amide and ester substituents (Deltanu(CO)), reveals that the ester- or amide-derivatized ligands are the ultimate acceptors and that the excited electron is localized on one acceptor ligand on the nanosecond time scale.

Synthesis, Characterization, and Photochemical/Photophysical Properties of Ruthenium(II) Complexes with Hexadentate Bipyridine and Phenanthroline Ligands.

Three hexadentate, podand-type, polypyridyl ligands, (5-bpy-2C)(3)Bz, (4-bpy-2C-Ph)(3)Et, and (4-phen-2C-Ph)(3)Et, and their Ru(II) and Fe(II) complexes have been prepared. Reaction of these ligands with Fe(II) produces only the monometallic hemicage species, while monometallic, bimetallic, and polymetallic Ru(II) complexes are formed. These species are separable by column chromatography, and NMR and ESI mass spectrometry demonstrate that with each ligand the first band to elute corresponds to the monometallic species, [RuL](2+).

Mid-Infrared Spectrum of [Ru(phen)(3)](2+).

Time-resolved infrared spectra in the fingerprint region (1300-1700 cm(-)(1)) are reported for the metal-to-ligand charge-transfer (MLCT) excited state(s) of [Ru(phen)(3)](2+) and [Os(phen)(DAS)(2)](2+) (phen is 1,10-phenanthroline; DAS is 1,2-bis(diphenylarsino)ethane) in acetonitrile-d(3) at 298 K. The spectra are assigned by comparison to electrochemically generated [Ru(III)(phen)(3)](3+) and [Ru(II)(phen(*)(-)())(phen)(2)](+). The data provide clear evidence for the localized description [Ru(III)(phen(*)(-)())(phen)(2)](2+) on the approximately 100 ns time scale.

Effect of Delocalization and Rigidity in the Acceptor Ligand on MLCT Excited-State Decay.

In its most simple form, the energy gap law for excited-state nonradiative decay predicts a linear dependence of ln k(nr) on the ground- to excited-state energy gap, where k(nr) is the rate constant for nonradiative decay. At this level of approximation, the energy gap law has been successfully applied to nonradiative decay in a wide array of MLCT excited states of polypyridyl complexes of Re(I), Ru(II), and Os(II). This relationship also predicts a dependence of k(nr) on the structural characteristics of the acceptor ligand.