Varying Substituents and Solvents To Maximize the Luminescence from [Ru(trpy)(bpy)CN]⁺ Derivatives

Ruthenium­(II) in combination with monodentate, bidentate, and tridentate ligands has proven to be a useful design for a variety of applications, but the majority of systems are virtually nonluminescent in solution. The goal of this work has been to design luminescent forms with practicable emission quantum yields, and the focus has been on [Ru­(X-T)­(dmeb)­CN]⁺ systems, where X-T denotes 2,2′:6′,2″-terpyridine bearing substituent X at the 4′-position and dmeb denotes [2,2′-bipyridine]-4,4′-dicarboxylic acid, dimethyl ester. Results show that varying the π-electron-donating ability of the 4′-X substituent is an effective way to tune the energy and lifetime of the charge-transfer (CT) emission. The lifetime achieved in a room-temperature, fluid solution is as high as 175 ns, depending on the 4′-substituent and the solvent employed because the excited state is very polar. That represents a 20-fold improvement in lifetime relative to that of the prototype, [Ru­(trpy)­(bpy)­CN]⁺, one of the earliest examples found to be luminescent in a fluid solution. A simple theoretical model proves to be capable of rationalizing all the experimental lifetimes. It suggests that, with the dmeb ligand available to accept the electron, enhancing the donor ability of the 4′-X substituent lowers the energy of the ³CT state and reduces the likelihood of thermally activated decay via a higher-energy d–d state. However, direct nonradiative decay to the ground state begins to reduce the excited-state lifetime whenever the emission maximum shifts beyond 750 nm. Within those limits, there is inevitably a maximal attainable lifetime, regardless of the method of tuning

Varying Substituents and Solvents To Maximize the Luminescence from [Ru(trpy)(bpy)CN]⁺ Derivatives

Ruthenium­(II) in combination with monodentate, bidentate, and tridentate ligands has proven to be a useful design for a variety of applications, but the majority of systems are virtually nonluminescent in solution. The goal of this work has been to design luminescent forms with practicable emission quantum yields, and the focus has been on [Ru­(X-T)­(dmeb)­CN]⁺ systems, where X-T denotes 2,2′:6′,2″-terpyridine bearing substituent X at the 4′-position and dmeb denotes [2,2′-bipyridine]-4,4′-dicarboxylic acid, dimethyl ester. Results show that varying the π-electron-donating ability of the 4′-X substituent is an effective way to tune the energy and lifetime of the charge-transfer (CT) emission. The lifetime achieved in a room-temperature, fluid solution is as high as 175 ns, depending on the 4′-substituent and the solvent employed because the excited state is very polar. That represents a 20-fold improvement in lifetime relative to that of the prototype, [Ru­(trpy)­(bpy)­CN]⁺, one of the earliest examples found to be luminescent in a fluid solution. A simple theoretical model proves to be capable of rationalizing all the experimental lifetimes. It suggests that, with the dmeb ligand available to accept the electron, enhancing the donor ability of the 4′-X substituent lowers the energy of the ³CT state and reduces the likelihood of thermally activated decay via a higher-energy d–d state. However, direct nonradiative decay to the ground state begins to reduce the excited-state lifetime whenever the emission maximum shifts beyond 750 nm. Within those limits, there is inevitably a maximal attainable lifetime, regardless of the method of tuning

Rigid Medium Effects on Photophysical Properties of MLCT Excited States of Polypyridyl Os(II) Complexes in Polymerized Poly(ethylene glycol)dimethacrylate Monoliths

Higher-energy emissions from the metal-to-ligand charge-transfer (MLCT) excited states of a series of polypyridyl Os­(II) complexes were observed at the fluid-to-film transition in PEG-DMA550. The higher-energy excited states, caused by a “rigid medium effect” in the film, led to enhanced emission quantum yields and longer excited-state lifetimes. Detailed analyses of spectra and excited-state dynamics by Franck–Condon emission spectral analysis and application of the energy gap law for nonradiative excited-state decay reveal that the rigid medium effect arises from the inability of part of the local medium dielectric environment to respond to the change in charge distribution in the excited state during its lifetime. Enhanced excited-state lifetimes are consistent with qualitative and quantitative predictions of the energy gap law

Competing Pathways in the <i>photo-</i>Proton-Coupled Electron Transfer Reduction of <i>fac</i>-[Re(bpy)(CO)₃(4,4′-bpy]^+* by Hydroquinone

The emitting metal-to-ligand charge transfer (MLCT) excited state of <i>fac</i>-[Re^I(bpy)(CO)₃(4,4′-bpy)]⁺ (<b>1</b>) (bpy is 2,2′-bipyridine, 4,4′-bpy is 4,4′-bipyridine), [Re^II(bpy^–•)(CO)₃(4,4′-bpy)]⁺*, is reductively quenched by 1,4-hydroquinone (H₂Q) in CH₃CN at 23 ± 2 °C by competing pathways to give a common electron–proton-transfer intermediate. In one pathway, electron transfer (ET) quenching occurs to give Re^I(bpy^–•)(CO)₃(4,4′-bpy)]⁰ with <i>k</i> = (1.8 ± 0.2) × 10⁹ M^–1 s^–1, followed by proton transfer from H₂Q to give [Re^I(bpy)(CO)₃(4,4′-bpyH^•)]⁺. Protonation triggers intramolecular bpy^•– → 4,4′-bpyH⁺ electron transfer. In the second pathway, preassociation occurs between the ground state and H₂Q at high concentrations. Subsequent Re → bpy MLCT excitation of the adduct is followed by electron–proton transfer from H₂Q in concert with intramolecular bpy^•– → 4,4′-bpyH⁺ electron transfer to give [Re^I(bpy)(CO)₃(4,4′-bpyH^•)]⁺ with <i>k</i> = (1.0 ± 0.4) × 10⁹ s^–1 in 3:1 CH₃CN/H₂O

Photodriven Oxygen Removal via Chromophore-Mediated Singlet Oxygen Sensitization and Chemical Capture

We report a general, photochemical method for the rapid deoxygenation of organic solvents and aqueous solutions via visible light excitation of transition metal chromophores (TMCs) in the presence of singlet oxygen scavenging substrates. Either 2,5-dimethylfuran or an amino acid (histidine or tryptophan methyl ester) was used as the substrate in conjunction with an iridium or ruthenium TMC in toluene, acetonitrile, or water. This behavior is described for solutions with chromophore concentrations that are pertinent for both luminescence and transient absorption spectroscopies. These results consistently produce TMC lifetimes comparable to those measured using traditional inert gas sparging and freeze–pump–thaw techniques. This method has the added benefits of providing long-term stability (days to months); economical preparation due to use of inexpensive, commercially available oxygen scrubbing substrates; and negligible size and weight footprints compared to traditional methods. Furthermore, attainment of dissolved [O₂] < 50 μM makes this method relevant to any solution application requiring low dissolved oxygen concentration in solution, provided that the oxygenated substrate does not interfere with the intended chemical process

An Amide-Linked Chromophore–Catalyst Assembly for Water Oxidation

The synthesis and analysis of a new amide-linked, dinuclear [Ru­(bpy)₂(bpy-ph-NH-CO-trpy)­Ru­(bpy)­(OH₂)]⁴⁺ (bpy = 2,2′-bipyridine; bpy-ph-NH-CO-trpy = 4-(2,2′:6′,2″-terpyridin-4′-yl)-<i>N</i>-[(4′-methyl-2,2′-bipyridin-4-yl)­methyl]­benzamide) assembly that incorporates both a light-harvesting chromophore and a water oxidation catalyst are described. With the saturated methylene linker present, the individual properties of both the chromophore and catalyst are retained including water oxidation catalysis and relatively slow energy transfer from the chromophore excited state to the catalyst

An analytical framework for delirium research in palliative care settings: integrated epidemiologic, clinician-researcher, and knowledge user perspectives

Context. Delirium often presents difficult management challenges in the context of goals of care in palliative care settings. Objectives. The aim was to formulate an analytical framework for further research on delirium in palliative care settings, prioritize the associated research questions, discuss the inherent methodological challenges associated with relevant studies, and outline the next steps in a program of delirium research.Methods. We combined multidisciplinary input from delirium researchers and knowledge users at an international delirium study planning meeting, relevant literature searches, focused input of epidemiologic expertise, and a meeting participant and coauthor survey to formulate a conceptual research framework and prioritize research questions.Results. Our proposed framework incorporates three main groups of research questions: the first was predominantly epidemiologic, such as delirium occurrence rates, risk factor evaluation, screening, and diagnosis; the second covers pragmatic management questions; and the third relates to the development of predictive models for delirium outcomes. Based on aggregated survey responses to each research question or domain, the combined modal ratings of "very'' or "extremely'' important confirmed their priority.Conclusion. Using an analytical framework to represent the full clinical care pathway of delirium in palliative care settings, we identified multiple knowledge gaps in relation to the occurrence rates, assessment, management, and outcome prediction of delirium in this population. The knowledge synthesis generated from adequately powered, multicenter studies to answer the framework's research questions will inform decision making and policy development regarding delirium detection and management and thus help to achieve better outcomes for patients in palliative care settings. (C) 2014 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved

Real Time <i>RT-PCR</i> detection of <i>TUSC2</i> gene expression in patients receiving DC-<i>TUSC2</i>.

1<p>Specimens not available.</p

Consort style flowchart of participants through the study.

<p>Consort style flowchart of participants through the study.</p

DC-<i>TUSC2</i> metabolic tumor response in a metastatic lung cancer patient.

<p>The patient is a 54 year old female with a large cell neuroendocrine carcinoma. She had received six prior chemotherapy regimens. Prior to entry in the protocol, two hepatic metastases were progressing on gemcitabine. The patient also had a metastasis in the head of the pancreas and a peripancreatic lymph node (arrows). A. Pretreatment PET scan. The dose of Fluorodeoxyglucose(18F) was 8.8mCi B. Post-treatment PET scan performed 20 days following the fourth dose of DC-<i>TUSC2</i>. The dose of Fluorodeoxyglucose(18F) was 9.0mCi. All scans were performed within a 60 to 90 minute window after injection.</p