Tuning Emission Lifetimes of Ir(C

Emissive compounds with long emission lifetimes (µs to ms) in the visible region are of interest for a range of applications, from oxygen sensing to cellular imaging. The emission behavior of Ir(ppy)2(acac) complexes (where ppy is the 2-phenylpyridyl chelate and acac is the acetylacetonate chelate) with an oligo(para-phenyleneethynylene) (OPE3) motif containing three para-rings and two ethynyl bridges attached to acac or ppy is examined here due to the accessibility of the long-lived OPE3 triplet states. Nine Ir(ppy)2(acac) complexes with OPE3 units are synthesized where the OPE3 motif is at the acac moiety (aOPE3), incorporated in the ppy chelate (pOPE3) or attached to ppy via a durylene link (dOPE3). The aOPE3 and dOPE3 complexes contain OPE3 units that are decoupled from the Ir(ppy)2(acac) core by adopting perpendicular ring-ring orientations, whereas the pOPE3 complexes have OPE3 integrated into the ppy ligand to maximize electronic coupling with the Ir(ppy)2(acac) core. While the conjugated pOPE3 complexes show emission lifetimes of 0.69-32.8 µs similar to the lifetimes of 1.00-23.1 µs for the non-OPE3 Ir(ppy)2(acac) complexes synthesized here, the decoupled aOPE3 and dOPE3 complexes reveal long emission lifetimes of 50-625 µs. The long lifetimes found in aOPE3 and dOPE3 complexes are due to intramolecular reversible electronic energy transfer (REET) where the long-lived triplet-state metal to ligand charge transfer (3MLCT) states exchange via REET with the even longer-lived triplet-state localized OPE3 states. The proposed REET process is supported by changes observed in excitation wavelength-dependent and time-dependent emission spectra from aOPE3 and dOPE3 complexes, whereas emission spectra from pOPE3 complexes remain independent of the excitation wavelength and time due to the well-established 3MLCT states of many Ir(ppy)2(acac) complexes. The long lifetimes, visible emission maxima (524-526 nm), and photoluminescent quantum yields of 0.44-0.60 for the dOPE3 complexes indicate the possibility of utilizing such compounds in oxygen-sensing and cellular imaging applications.

Cyclophane Molecules Exhibiting Thermally Activated Delayed Fluorescence: Linking Donor Units to Influence Molecular Conformation.

The synthetic methodology to covalently link donors to form cyclophane-based thermally activated delayed fluorescence (TADF) molecules is presented. These are the first reported examples of TADF cyclophanes with "electronically innocent" bridges between the donor units. Using a phenothiazine-dibenzothiophene-S,S-dioxide donor-acceptor-donor (D-A-D) system, the two phenothiazine (PTZ) donor units were linked by three different strategies: (i) ester condensation, (ii) ether synthesis, and (iii) ring closing metathesis. Detailed X-ray crystallographic, photophysical and computational analyses show that the cyclophane molecular architecture alters the conformational distribution of the PTZ units, while retaining a certain degree of rotational freedom of the intersegmental D-A axes that is crucial for efficient TADF. Despite their different structures, the cyclophanes and their nonbridged precursors have similar photophysical properties since they emit through similar excited states resulting from the presence of the equatorial conformation of their PTZ donor segments. In particular, the axial-axial conformations, known to be detrimental to the TADF process, are suppressed by linking the PTZ units to form a cyclophane. The work establishes a versatile linking strategy that could be used in further functionalization while retaining the excellent photophysical properties of the parent D-A-D system.

Impact of Methoxy Substituents on Thermally Activated Delayed Fluorescence and Room-Temperature Phosphorescence in All-Organic Donor-Acceptor Systems.

Thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) are known to occur in organic D-A-D and D-A systems where the donor group contains the phenothiazine unit and the acceptor is dibenzothiophene- S, S-dioxide. This study reports the synthesis and characterization of one new D-A and four new D-A-D systems with methoxy groups on the phenothiazine to examine their effect on emission properties in the zeonex matrix. X-ray analysis and highly specialized NMR techniques were used to characterize asymmetric methoxy-substituted derivative 3b, which is chiral at N because of an extremely high flipping barrier at the phenothiazine N atom. Based on hybrid-density functional theory computations, the methoxy substituents tune the relative stabilities of the axial conformers with respect to equatorial conformers of the phenothiazine units, depending on their substitution position. This conformational effect significantly influences both TADF and RTP contributions compared to the parent D-A-D system. It is also demonstrated that the equatorial forms of D-A-D and D-A systems in zeonex exhibit TADF. Additionally, the methoxy groups promote luminescence in D-A-D systems where only axial conformers exist. This work reveals further design opportunities for more efficient TADF and RTP molecules.

Synthetic, Structural, and Computational Studies on Heavier Tetragen and Chalcogen Triazenide Complexes.

The syntheses of the triazenide complexes [{N(NDipp)2}2M] (Dipp = 2,6-di-isopropylphenyl; M = Ge(II) (1), Sn(II) (2), Pb(II) (3), and Te(II) (5)) are described for the first time. These compounds have been characterized by single-crystal X-ray diffraction and heteronuclear NMR spectroscopy. Density functional theory calculations were employed to confirm the presence and nature of the stereochemically active lone pairs in 1-5, alongside the Gibbs energy changes for their general synthesis, which enable the rationalization of observed reactivities.

Unravelling the Complexities of Pseudocontact Shift Analysis in Lanthanide Coordination Complexes of Differing Symmetry.

In two closely related series of eight-coordinate lanthanide complexes, a switch in the sign of the dominant ligand field parameter and striking variations in the sign, amplitude and orientation of the main component of the magnetic susceptibility tensor as the Ln3+ ion is permuted conspire to mask modest changes in NMR paramagnetic shifts, but are evident in Yb EPR and Eu emission spectra.

Role of the Diphosphine Chelate in Emissive, Charge-Neutral Iridium(III) Complexes.

A class of neutral tris-bidentate IrIII metal complexes incorporating a diphosphine as a chelate is prepared and characterized here for the first time. Treatment of [Ir(dppBz)(tht)Cl3 ] (1, dppBz=1,2-bis(diphenylphosphino)benzene, tht=tetrahydrothiophene) with fppzH (3-trifluoromethyl-5-(2'-pyridyl)-1H-pyrazole) afforded the dichloride complexes, trans-(Cl,Cl)[Ir(dppBz)(fppz)Cl2 ] (2) and cis-(Cl,Cl)[Ir(dppBz)(fppz)Cl2 ] (3). The reaction of 3 with the dianionic chelate precursor, 5,5'-di(trifluoromethyl)-3,3'-bipyrazole (bipzH2 ) or 5,5'-(1-methylethylidene)-bis(3-trifluoromethyl-1H-pyrazole) (mepzH2 ), in DMF gave the tris-bidentate complex [Ir(dppBz)(fppz)(bipz)] (4) or [Ir(dppBz)(fppz)(mepz)] (5), respectively. In contrast, a hydride complex [Ir(dppBz)(fppz)(bipzH)H] (6) was isolated instead of 4 in protic solvent, namely: diethylene glycol monomethyl ether (DGME). All complexes 2-6 are luminescent in powder form and thin films where the dichlorides (2, 3) emit with maxima at 590-627 nm (orange) and quantum yields (QYs) up to 90 % whereas the tris-bidentate (4, 5) and hydride (6) complexes emit at 455-458 nm (blue) with QYs up to 70 %. Hybrid (time-dependent) DFT calculations showed considerable metal-to-ligand charge transfer contribution to the orange-emitting 2 and 3 but substantial ligand-centered 3 π-π* transition character in the blue-emitting 4-6. The dppBz does not participate in the radiative transitions in 4-6, but it provides the rigidity and steric bulk needed to promote the luminescence by suppressing the self-quenching in the solid state. Fabrication of an organic light-emitting diode (OLED) with dopant 5 gave a deep-blue CIE chromaticity of (0.16, 0.15). Superior blue emitters, which are vital in OLED applications, may be found in other neutral IrIII complexes containing phosphine chelates.

Bond Rotations and Heteroatom Effects in Donor-Acceptor-Donor Molecules: Implications for Thermally Activated Delayed Fluorescence and Room Temperature Phosphorescence.

The synthesis of 1-methylphenoxazine via CO2-directed lithiation chemistry is reported. This electron donor was coupled with 2,8-dibromodibenzothiophene- S, S-dioxide with Buchwald-Hartwig chemistry to give a new donor-acceptor-donor charge-transfer fluorescent molecule 1b. X-ray crystal structures and calculations show that the phenoxazinyl groups are coplanar and equatorial (eq) to the acceptor plane in nonmethylated 1a but are pyramidal and axial (ax) in 1b. The bond rotation energy barriers between donor and acceptor groups for 1a and 1b are only 0.13 and 0.19 eV, respectively, from hybrid-DFT computations at the CAM-B3LYP/6-31G(d) level. Many possible conformers are present in solutions and in zeonex. In zeonex, the methyl groups in 1b shift the emission band 0.13 eV higher in energy compared to 1a. Excited state eq-eq and ax-ax geometries were identified with DFT calculations with charge transfer (CT) emission assigned as 1CT(eq) and 1CT(ax) dominating. The lower energy 1CT(eq) contributes to thermally activated delayed fluorescence, whereas the higher energy 1CT(ax) does not. Phenothiazine analogues 2a and 2b also have major fluorescence emissions assigned as 1CT(eq) and 1CT(ax), respectively. 2a and 2b have substantial room temperature phosphorescence (RTP), whereas 1a and 1b do not, highlighting the importance of the sulfur atom in 2a and 2b to obtain RTP emission.

The TEMPO Trial at 5 Years: Transoral Fundoplication (TIF 2.0) Is Safe, Durable, and Cost-effective.

BACKGROUND: Questions remain about the therapeutic durability of transoral incisionless fundoplication (TIF). In this study, clinical outcomes were evaluated at 5 years post-TIF 2.0. METHODS: A total of 63 chronic gastroesophageal reflux disease (GERD) sufferers with troublesome symptoms refractory to proton pump inhibitor (PPI) therapy, absent or ≤2 cm hiatal hernia, and abnormal esophageal acid exposure were randomized to the TIF group or PPI group. Following the 6-month evaluation, all patients in the PPI group elected for crossover to TIF; therefore, all 63 patients underwent TIF 2.0 with EsophyX2 device. Primary outcome was elimination of daily troublesome regurgitation and atypical symptoms at the 5-year follow-up. Secondary outcomes were improvement in symptom scores, PPI use, reoperations, and patient health satisfaction. The cost-effectiveness of TIF 2.0 was also estimated. RESULTS: Of 63 patients, 60 were available at 1 year, 52 at 3 years, and 44 at 5 years for evaluation. Troublesome regurgitation was eliminated in 88% of patients at 1 year, 90% at 3 years, and 86% at 5 years. Resolution of troublesome atypical symptoms was achieved in 82% of patients at 1 year, 88% at 3 years, and 80% at 5 years. No serious adverse events occurred. There were 3 reoperations by the end of the 5-year follow-up. At the 5-year follow-up, 34% of patients were on daily PPI therapy as compared with 100% of patients at screening. The total GERD Health-related quality-of-life score improved by decreasing from 22.2 to 6.8 at 5 years ( P < .001). CONCLUSION: In this patient population, the TIF 2.0 procedure provided safe and sustained long-term elimination of troublesome GERD symptoms.

Monitoring of the ADP/ATP Ratio by Induced Circularly Polarised Europium Luminescence.

A series of three europium complexes bearing picolyl amine moieties was found to possess differing binding affinities towards Zn2+ and three nucleotides: AMP, ADP, and ATP. A large increase in the total emission intensity was observed upon binding Zn2+ , followed by signal amplification upon the addition of nucleotides. The resulting adducts possessed strong induced circularly polarised emission, with ADP and ATP signals of opposite sign. Model DFT geometries of the adducts suggest the Δ diastereoisomer is preferred for ATP and the Λ isomer for ADP/AMP. This change in sign allows the ADP/ATP (or AMP/ATP) ratio to be assessed by monitoring changes in the emission dissymmetry factor, gem .

Transoral fundoplication offers durable symptom control for chronic GERD: 3-year report from the TEMPO randomized trial with a crossover arm.

BACKGROUND: Four randomized controlled trials have demonstrated the short-term efficacy and safety of transoral esophagogastric fundoplication (TF) performed with the EsophyX® device in eliminating troublesome gastroesophageal reflux disease (GERD) symptoms in well-selected patient populations. The aim of this study was to assess the durability of these outcomes at 3 years post-procedure. METHODS: The TF EsophyX versus Medical PPI Open Label trial was conducted in seven US sites. Between June and August 2012, we enrolled patients with small (<2 cm) or absent hiatal hernias who suffered from troublesome GERD symptoms while on PPI therapy for at least 6 months and had abnormal esophageal acid exposure (EAE). Randomization was to TF group (n = 40) or to PPI group (n = 23). Following evaluation at 6 months, all remaining PPI patients (n = 21) elected to undergo crossover to TF. Fifty-two patients were assessed at 3 years for (1) GERD symptom resolution using three GERD-specific quality of life questionnaires, (2) healing of esophagitis using endoscopy, (3) EAE using 48-h Bravo testing, and (4) discontinuation of PPI use. Two patients who underwent revisional procedures by year 3 were included in the final analysis. RESULTS: At 3-year follow-up, elimination of troublesome regurgitation and all atypical symptoms was reported by 90 % (37/41) and 88 % (42/48) of patients, respectively. The mean Reflux Symptom Index score improved from 22.2 (9.2) on PPIs at screening to 4 (7.1) off PPIs 3 years post-TF, p < 0.0001. The mean total % time pH <4 improved from 10.5 (3.5) to 7.8 (5.7), p = 0.0283. Esophagitis was healed in 86 % (19/22) of patients. At the end of study, 71 % (37/52) of patients had discontinued PPI therapy. All outcome measures remained stable between 1-, 2-, and 3-year follow-ups. CONCLUSION: This study demonstrates that TF can be used to achieve long-term control of chronic GERD symptoms, healing of esophagitis, and improvement in EAE.

Biotransformation of fluorophenyl pyridine carboxylic acids by the model fungus Cunninghamella elegans.

1. Fluorine plays a key role in the design of new drugs and recent FDA approvals included two fluorinated drugs, tedizolid phosphate and vorapaxar, both of which contain the fluorophenyl pyridyl moiety. 2. To investigate the likely phase-I (oxidative) metabolic fate of this group, various fluorinated phenyl pyridine carboxylic acids were incubated with the fungus Cunninghamella elegans, which is an established model of mammalian drug metabolism. 3. 19F NMR spectroscopy established the degree of biotransformation, which varied depending on the position of fluorine substitution, and gas chromatography-mass spectrometry (GC-MS) identified alcohols and hydroxylated carboxylic acids as metabolites. The hydroxylated metabolites were further structurally characterised by nuclear magnetic resonance spectroscopy (NMR), which demonstrated that hydroxylation occurred on the 4' position; fluorine in that position blocked the hydroxylation. 4. The fluorophenyl pyridine carboxylic acids were not biotransformed by rat liver microsomes and this was a consequence of inhibitory action, and thus, the fungal model was crucial in obtaining metabolites to establish the mechanism of catabolism.

Oligo(p-phenyleneethynylene) (OPE) molecular wires: synthesis and length dependence of photoinduced charge transfer in OPEs with triarylamine and diaryloxadiazole end groups.

The systematic synthesis and photophysical, electrochemical and computational studies on an extended series of triphenylamine-[C≡C-1,4-C6H2(OR)2]n-C≡C-diphenyl-1,3,4-oxadiazole dyad molecules (the OR groups are at 2,5-positions of the para-phenylene ring and R = C6H13; n = 0-5, compounds 1, 2, 3, 4 and 5, respectively) are reported. Related molecules with identical end groups, triphenylamine-C≡C-1,4-C6H2(OR)2-C≡C-triphenylamine (R = C6H13; 6) and diphenyl-1,3,4-oxadiazole-[C≡C-C6H2(OR)2]2-C≡C-diphenyl-1,3,4-oxadiazole (R = C6H13; 7) were also studied. These D-B-A 1-5, D-B-D 6 and A-B-A 7 (D = electron donor, B = bridge, A = electron acceptor) systems were synthesized using palladium-catalysed cross-coupling reactions of new p-phenyleneethynylene building blocks. Steady-state emission studies on the dyads 1-5 reveal a complicated behavior of the emission that is strongly medium dependent. In low polarity solvents the emission is characterized by a sharp high-energy peak attributed to fluorescence from a locally excited (LE) state. In more polar environments the LE state is effectively quenched by transfer into an intramolecular charge-transfer (ICT) state. The medium dependence is also observed in the quantum yields (QYs) which are high in cyclohexane and low in acetonitrile, thus also indicating charge-transfer character. Low-temperature emission spectra for 2-5 in dichloromethane and diethyl ether also reveal two distinct excited states, namely the LE state and the conventional ICT state, depending on solvent and temperature. Hybrid DFT calculations for 1-7 establish that the OPE bridge is involved in both frontier orbitals where the bridge character increases as the bridge length increases. Computed TD-DFT data on 1-5 assign the emission maxima in cyclohexane as LE transitions. Each time-resolved emission measurement on 2-7 in cyclohexane and diethyl ether reveals a wavelength dependent bi-exponential decay of the emission with a fast component in the 5-61 ps range on blue detection and a slower approximately 1 ns phase, independent of detection wavelength. The fast component is attributed to LE fluorescence and this emission component is rate limited and quenched by transfer into an ICT state. The fast LE fluorescence component varies systematically with conjugation length for the series of D-B-A dyads 2-5. An attenuation factor ß of 0.15 Å(-1) was determined in accordance with an ICT superexchange mechanism.

An Experimental and Computational Approach to Understanding the Reactions of Acyl Nitroso Compounds in [4 + 2] Cycloadditions.

Catalytic aerobic oxidation of phenyl hydroxycarbamate 1 and 1-hydroxy-3-phenylurea 2 using CuCl2 and 2-ethyl-2-oxazoline in methanol gave acyl nitroso species in situ, which were trapped in nitroso-Diels-Alder (NDA) reactions with various dienes to afford the corresponding cycloadducts in high yields (90-98%). Competing ene products were also present for dienes containing both alkene π-bonds and allylic σ-bonds, and the ene yields are higher with 1 than with 2. The use of the chiral hydroxamic acid, (R)-1-hydroxy-3-(1-phenylethylurea) 3 (same conditions) gave NDA cycloadducts in high yields (97-99%) with no ene product from 2,3-dimethyl-1,3-butadiene. NDA cycloadducts were not obtained from other hydroxamic acid analogues [RCONHOH (R = PhCH2 4; Ph(CH2)2 5; Ph(CH2)3 6; Ph(CH2)4 7; Ph 8; 2-pyridyl 9; 3-pyridyl 10] with various dienes using copper-oxidation but rather were obtained using sodium periodate, resulting in variable NDA yields (13-51%) from hydroxamic acids 1-10 with cyclohexa-1,3-diene and 2,3-dimethyl-1,3-butadiene (several cycloadducts characterized by X-ray crystallography). The NDA and nitroso-ene reaction pathways of nitroso intermediates with dienes were mapped by DFT computations (B3LYP/6-31G*), which showed that the acyl nitroso species are super-reactive and that activation energies in the NDA processes are lower than the isomerization barriers between some cis- and trans-butadienes.

Ir(III)-Based Phosphors with Bipyrazolate Ancillaries; Rational Design, Photophysics, and Applications in Organic Light-Emitting Diodes.

A series of three charge-neutral Ir(III) complexes bearing both neutral chelating ligands 4,4'-di-t-butyl-2,2'-bipyridine (dtbbpy) and monoanionic cyclometalated ligands derived from 2-phenylpyridine (ppyH), together with either two monoanionic ligands (i.e., chloride and monodentate pyrazolate) or a single dianionic chelate derived from 5,5'-di(trifluoromethyl)-3,3'-bipyrazole (bipzH2) or 5,5'-(1-methylethylidene)-bis-(3-trifluoromethyl-1H-pyrazole) (mepzH2), was successfully synthesized. These complexes are derived from a common, structurally characterized, Ir(III) intermediate complex [Ir(dtbbpy) (ppy)Cl2] (1), from treatment of IrCl3·3H2O with equal amount of the diimine (N^N) and precursor of the cyclometalated (C^N) ligands in a form of one-pot reaction. Treatment of 1 with various functional pyrazoles afforded [Ir(dtbbpy) (ppy) (pz)Cl] (2), [Ir(dtbbpy) (ppy) (bipz)] (3), and [Ir(dtbbpy) (ppy) (mepz)] (4), which display intense room-temperature emission with λmax spanning the region between 532 and 593 nm in both fluid and solid states. The Ir(III) complexes, 3 and 4, showcase rare examples of three distinctive chelates (i.e., neutral, anionic, and dianionic) assembled around the central Ir(III) cation. Hybrid density functional theory (DFT; B3LYP) electronic structure calculations on 1-4 reveal the lowest unoccupied molecular orbital to be π*(bpy) in character for all complexes and highest occupied molecular orbital (HOMO) offering d(Ir)-π(phenyl) character for 1, 2, and 4 and π(bipz) character for 3. The different HOMO composition of 3 and 4 is also predicted by calculations using pure DFT (BLYP) and wave function (MP2) methods. On the basis of time-dependent DFT calculations, the emissive processes are dominated by the phenyl group-to-bipyridine, ligand(ppy)-to-ligand(bpy) charge transfer admixed with metal-to-ligand transition for all Ir(III) complexes. Organic light emitting diodes were successfully fabricated. A double emitting layer design was adopted in the device architecture using Ir(III) metal complexes 3 and 4, attaining peak external quantum efficiencies, luminance efficiencies, and power efficiencies of 18.1% (59.0 cd/A and 38.6 lm/W) and 16.6% (53.3 cd/A and 33.5 lm/W), respectively.

Challenging lanthanide relaxation theory: erbium and thulium complexes that show NMR relaxation rates faster than dysprosium and terbium analogues.

Measurements of the proton NMR paramagnetic relaxation rates for several series of isostructural lanthanide(III) complexes have been performed in aqueous solution over the field range 1.0 to 16.5 Tesla. The field dependence has been modeled using Bloch-Redfield-Wangsness theory, allowing values for the electronic relaxation time, Tle and the magnetic susceptibility, µeff, to be estimated. Anomalous relaxation rate profiles were obtained, notably for erbium and thulium complexes of low symmetry 8-coordinate aza-phosphinate complexes. Such behaviour challenges accepted theory and can be interpreted in terms of changes in Tle values that are a function of the transient ligand field induced by solvent collision and vary considerably between Ln(3+) ions, along with magnetic susceptibilities that deviate significantly from free-ion values.

Transoral incisionless fundoplication effective in eliminating GERD symptoms in partial responders to proton pump inhibitor therapy at 6 months: the TEMPO Randomized Clinical Trial.

BACKGROUND: Incomplete control of troublesome regurgitation and extraesophageal manifestations of chronic gastroesophageal reflux disease (GERD) is a known limitation of proton pump inhibitor (PPI) therapy. This multicenter randomized study compared the efficacy of transoral incisionless fundoplication (TIF) against PPIs in controlling these symptoms in patients with small hiatal hernias. METHODS: Between June and August 2012, 63 patients were randomized at 7 US community hospitals. Patients in the PPI group were placed on maximum standard dose (MSD). Patients in the TIF group underwent esophagogastric fundoplication using the EsophyX2 device. Primary outcome was elimination of daily troublesome regurgitation or extraesophageal symptoms. Secondary outcomes were normalization of esophageal acid exposure (EAE), PPI usage and healing of esophagitis. RESULTS: Of 63 randomized patients (40 TIF and 23 PPI), 3 were lost to follow-up leaving 39 TIF and 21 PPI patients for analysis. At 6-month follow-up, troublesome regurgitation was eliminated in 97% of TIF patients versus 50% of PPI patients, relative risk (RR) = 1.9, 95% confidence interval (CI) = 1.2-3.11 (P = .006). Globally, 62% of TIF patients experienced elimination of regurgitation and extraesophageal symptoms versus 5% of PPI patients, RR = 12.9, 95% CI = 1.9-88.9 (P = .009). EAE was normalized in 54% of TIF patients (off PPIs) versus 52% of PPI patients (on MSD), RR = 1.0, 95% CI = 0.6-1.7 (P = .914). Ninety percent of TIF patients were off PPIs. CONCLUSION: At 6-month follow-up, TIF was more effective than MSD PPI therapy in eliminating troublesome regurgitation and extraesophageal symptoms of GERD.

Mixed-valence ruthenium complexes rotating through a conformational Robin-Day continuum.

The conformational energy landscape and the associated electronic structure and spectroscopic properties (UV/Vis/near-infrared (NIR) and IR) of three formally d(5)/d(6) mixed-valence diruthenium complex cations, [{Ru(dppe)Cp*}2(µ-C≡CC6H4C≡C)](+), [1](+), [trans-{RuCl(dppe)2}2(µ-C≡CC6H4C≡C)](+), [2](+), and the Creutz-Taube ion, [{Ru(NH3)5}2(µ-pz)](5+), [3](5+) (Cp = cyclopentadienyl; dppe = 1,2-bis(diphenylphosphino)ethane; pz = pyrazine), have been studied using a nonstandard hybrid density functional BLYP35 with 35 % exact exchange and continuum solvent models. For the closely related monocations [1](+) and [2](+), the calculations indicated that the lowest-energy conformers exhibited delocalized electronic structures (or class III mixed-valence character). However, these minima alone explained neither the presence of shoulder(s) in the NIR absorption envelope nor the presence of features in the observed vibrational spectra characteristic of both delocalized and valence-trapped electronic structures. A series of computational models have been used to demonstrate that the mutual conformation of the metal fragments--and even more importantly the orientation of the bridging ligand relative to those metal centers--influences the electronic coupling sufficiently to afford valence-trapped conformations, which are of sufficiently low energy to be thermally populated. Areas in the conformational phase space with variable degrees of symmetry breaking of structures and spin-density distributions are shown to be responsible for the characteristic spectroscopic features of these two complexes. The Creutz-Taube ion [3](5+) also exhibits low-lying valence-trapped conformational areas, but the electronic transitions that characterize these conformations with valence-localized electronic structures have low intensities and do not influence the observed spectroscopic characteristics to any notable extent.

Univariate and multivariate analyses of preoperative factors influencing symptomatic outcomes of transoral fundoplication.

BACKGROUND: Preoperative factors predicting symptomatic improvement after transoral fundoplication (TF) in chronic gastroesophageal reflux disease (GERD) patients with persistent symptoms on proton-pump inhibitors (PPIs) therapy have not been elucidated fully. METHODS: Univariate and multivariate logistic regression analyses were performed on data from 158 consecutive patients who underwent TF with the EsophyX device between January 2010 and June 2012 in 14 community centers. Variables included age, gender, body mass index, GERD duration, PPIs therapy duration, presence of hiatal hernia, esophagitis, Hill grade, quality of life scores (QOL) on PPIs, % total time pH < 4, and DeMeester score on reflux testing off PPIs. RESULTS: All patients suffered from typical GERD symptoms. Additionally, 78% (124/158) of patients suffered from atypical symptoms. Six percent (10/158) with recurrent GERD symptoms refractory to PPI therapy underwent revisional procedure (9 laparoscopic Nissen, 1 TF). Median follow-up was 22 (range 10-43) months. For patients with typical symptoms, univariate analyses revealed 4 preoperative factors predictive of successful outcomes: age ≥ 50 [odds ratio (OR) = 2.4, 95% confidence interval (CI) = 1.2-4.8, p = 0.014], GERD Health-related Quality of Life score (GERD-HRQL) ≥ 15 on PPIs (OR = 6.0, CI = 1.2-29.4, p = 0.026, Reflux Symptom Index score > 13 on PPIs (OR = 2.4, CI = 1.1-5.2, p = 0.027), and Gastroesophageal Reflux Symptom Score ≥ 18 on PPIs (OR = 2.6, CI = 1.2-5.8, p = 0.018). Age and GERD-HRQL score remained significant predictors by multivariate analysis. For patients with atypical symptoms, only GERD-HRQL score ≥ 15 on PPIs (OR = 9.9, CI = 0.9-4.6, p = 0.036) was associated with successful outcomes. CONCLUSIONS: Elevated preoperative QOL scores on PPIs and age ≥ 50 were most closely associated with successful outcome of TF in patients with persistent symptoms despite medical therapy.

Crystal structures of the carborane dianions [1,4-(PhCB10H10C)2C6H4]²â» and [1,4-(PhCB10H10C)2C6F4]²â» and the stabilizing role of the para-phenylene unit on 2n+3 skeletal electron clusters.

While carboranes with 2 n+2 and 2 n+4 (n=number of skeletal atoms) skeletal electrons (SE) are widely known, little has been reported on carboranes with odd SE numbers. Electrochemical measurements on two-cage assemblies, where two C-phenyl-ortho-carboranyl groups are linked by a para-phenylene or a para-tetrafluorophenylene bridge, revealed two well separated and reversible two-electron reduction waves indicating formation of stable dianions and tetraanions. The salts of the dianions were isolated by reduction with sodium metal and their unusual structures were determined by X-ray crystallography. The diamagnetic dianions contain two 2 n+3 SE clusters where each cluster has a notably long carborane C-carborane C distance of ca 2.4 Å. The π conjugation within the phenylene bridge plays an important role in the stabilization of these carboranes with odd SE counts.

Bimetallic cyclometalated iridium(III) diastereomers with non-innocent bridging ligands for high-efficiency phosphorescent OLEDs.

Two phosphorescent dinuclear iridium(III) diastereomers (ΛΔ/ΔΛ) and (ΛΛ/ΔΔ) are readily separated by making use of their different solubilities in hot hexane. The bridging diarylhydrazide ligand plays an important role in the electrochemistry and photophysics of the complexes. Organic light-emitting devices (OLEDs) that use these complexes as the green-emissive dopants in solution-processable single-active-layer architectures feature electroluminescence efficiencies that are remarkably high for dinuclear metal complexes, achieving maximum values of 37 cd A(-1), 14 lm W(-1), and 11% external quantum efficiency.