Discovery of a hyperalkaline liquid condensed phase: significance toward applications in carbon dioxide sequestration.

Bicarbonate ion-containing solutions such as seawater, natural brines, bovine serum and other mineralizing fluids have been found to contain hyperalkaline droplets of a separate, liquid condensed phase (LCP), that have higher concentrations of bicarbonate ion (HCO3 -) relative to the bulk solution in which they reside. The existence and unique composition of the LCP droplets have been characterized by nanoparticle tracking analysis, nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, dissolved inorganic carbon analysis and refractive index measurements. Carbon dioxide can be brought into solution through an aqueous reaction to form LCP droplets that can then be separated by established industrial membrane processes as a means of concentrating HCO3 -. Reaction of calcium with the LCP droplets results in calcium carbonate precipitation and mineral formation. The LCP phenomenon may bear on native mineralization reactions and has the potential to change fundamental approaches to carbon capture, sequestration and utilization.

High-resolution Spatiotemporal Dynamics of Harmful Algae in the Indian River Lagoon (Florida)-A Case Study of Aureoumbra lagunensis, Pyrodinium bahamense, and Pseudo-nitzschia.

The Indian River Lagoon (IRL), located on the east coast of Florida, is a complex estuarine ecosystem that is negatively affected by recurring harmful algal blooms (HABs) from distinct taxonomic/functional groups. Enhanced monitoring was established to facilitate rapid quantification of three recurrent bloom taxa, Aureoumbra lagunensis, Pyrodinium bahamense, and Pseudo-nitzschia spp., and included corroborating techniques to improve the identification of small-celled nanoplankton (<10 µm in diameter). Identification and enumeration of these target taxa were conducted during 2015-2020 using a combination of light microscopy and species-specific approaches, specifically immunofluorescence flow cytometry as well as a newly developed qPCR assay for A. lagunensis presented here for the first time. An annual bloom index (ABI) was established for each taxon based on occurrence and abundance data. Blooms of A. lagunensis (>2×108 cells L-1) were observed in all six years sampled and across multiple seasons. In contrast, abundance of P. bahamense, largely driven by the annual temperature cycle that moderates life cycle transitions and growth, displayed a strong seasonal pattern with blooms (105-107 cells L-1) generally developing in early summer and subsiding in autumn. However, P. bahamense bloom development was delayed and abundance was significantly lower in years and locations with sustained A. lagunensis blooms. Pseudo-nitzschia spp. were broadly distributed with sporadic bloom concentrations (reaching 107 cells L-1), but with minimal concentrations of the toxin domoic acid detected (<0.02 µg L-1). In summer 2020, multiple monitoring tools characterized a novel nano-cyanobacterium bloom (reaching 109 cells L-1) that coincided with a decline in A. lagunensis and persisted into autumn. Statistical and time-series analyses of this spatiotemporally intensive dataset highlight prominent patterns in variability for some taxa, but also identifies challenges of characterizing mechanisms underlying more episodic yet persistent events. Nevertheless, the intersect of temperature and salinity as environmental proxies proved to be informative in delineating niche partitioning, not only in the case of taxa with long-standing data sets but also for seemingly unprecedented blooms of novel nanoplanktonic taxa.

Quantitative Measurement of the Improvement Derived From a 10-Mo Progressive Exercise Program to Improve Balance and Function in Women at Increased Risk for Fragility Fractures.

INTRODUCTION/BACKGROUND: Osteoporosis is a common disorder and is associated with an increased risk of bone fracture. Falls are a proximate cause of a high proportion of medical costs and mortality. Improving balance can reduce the risk of falls and improve health outcomes, especially for the at-risk population of people with osteoporosis and osteopenia. The FrameWorksTM exercise program is a formal, standardized, informational and interventional 10-month exercise program. The purpose of this study was to quantitatively assess the improvement in standing balance, functional reach, and overall confidence in balance after participating in the 10-month program. METHODOLOGY: This study is a prospectively designed study with a pre and post study measurement of balance metrics. Sixty-two female participants, 45 years of age or older and at increased risk for fragility fractures, completed the 10-month program as well the pre and post program testing. Confidence was measured with the Activities-specific Balance Confidence Scale, a self-reported survey. Balance was measured digitally by means of testing with a NeuroCom® Basic Balance Master® system. Measurements were made of the Limits of Stability (LOS) Test and Modified Clinical Test of Sensory Interaction on Balance (mCTSIB). Balance was clinically assessed with the Functional Reach Test (FRT). RESULTS: Participation in the 10 months FrameWorksTM program resulted in improvement in quantitative measures of balance (Composite Sway Velocity, -12%, p < 0.001; End point excursion, 17.1%, p < 0.000001). A clinical measure of balance, the Functional Reach Test, improved, (2.9 cm, p < 0.0001). Participation also resulted in improvement in balance confidence (9.4 %, p < 0.00001). A height increase was observed (0.6 cm, p < 0.000001). CONCLUSIONS: The 10-month FrameWorksTM program improves balance and confidence in women at risk for fragility fractures. By improving balance and confidence, people are less likely to fall and therefore sustain fewer fractures and associated injuries.

Tungsten carbide-nitride on graphene nanoplatelets as a durable hydrogen evolution electrocatalyst.

Alternatives to platinum-based catalysts are required to sustainably produce hydrogen from water at low overpotentials. Progress has been made in utilizing tungsten carbide-based catalysts, however, their performance is currently limited by the density and reactivity of active sites, and insufficient stability in acidic electrolytes. We report highly active graphene nanoplatelet-supported tungsten carbide-nitride nanocomposites prepared via an in situ solid-state approach. This nanocomposite catalyzes the hydrogen evolution reaction with very low overpotential and is stable operating for at least 300 h in harsh acidic conditions. The synthetic approach offers a great advantage in terms of structural control and kinetics improvement.

Concentric craniotomy: removal of tumor involving the skull and the intracranial space.

BACKGROUND: Removal of a tumor involving both the intracranial space and the skull presents technical challenges. This is especially so if there is a potential for significant hemorrhage due to a hemangioma or a significant attachment to the brain as with a meningioma. CASE DESCRIPTION: We describe a technique where the tumor attached to the skull is left undisturbed and a second wider concentric craniotomy exposes normal dura. The entire tumor, both intracranial and that involving the skull and dura, can then be removed as one specimen. CONCLUSION: The technique we describe, a concentric craniotomy, transforms a difficult operation with the potential for significant hemorrhage into a more standard removal of a convexity tumor.

Adrenocortical carcinoma in a 3% years old girl with hetro-sexual precocity.

Adrenocortical carcinoma is a rare neoplasm in children. Hetro-sexual precocious puberty could be the initial presentation of a rare adrenocortical neoplasm in the pediatric age group. Features of hetro-sexual precocious puberty in a girl should alert the possibility of such a rare disease. We report a rare case of adrenocortical carcinoma in a three years and six months old girl who presented with hetro-sexual precocious puberty of two years duration. Left adrenalectomy was done and histopathology revealed adrenocortical carcinoma.

CO2 photoreduction with long-wavelength light: dyads and monomers of zinc porphyrin and rhenium bipyridine.

Photocatalytic CO(2) reduction has been studied for two dyads with porphyrin covalently attached to rhenium tricarbonyl bipyridine moieties, and on separate components consisting of [Re(CO)(3)(Picoline)Bpy](+) and either zinc porphyrin or zinc chlorin. TONs decrease in the order: zinc porphyrin + Re > long spacer dyad > zinc chlorin + Re > short spacer dyad.

Thermodynamics and kinetics of CO2, CO, and H+ binding to the metal centre of CO2 reduction catalysts.

In our developing world, carbon dioxide has become one of the most abundant greenhouse gases in the atmosphere. It is a stable, inert, small molecule that continues to present significant challenges toward its chemical activation as a useful carbon end product. This tutorial review describes one approach to the reduction of carbon dioxide to carbon fuels, using cobalt and nickel molecular catalysts, with particular focus on studying the thermodynamics and kinetics of CO(2) binding to metal catalytic sites.

Photochemistry and photophysics of a Pd(II) metalloporphyrin: Re(I) tricarbonyl bipyridine molecular dyad and its activity toward the photoreduction of CO2 to CO.

The photochemistry and photophysics of the cationic molecular dyad, 5-{4-[rhenium(I)tricarbonylpicoline-4-methyl-2,2'-bipyridine-4'-carboxyamidyl]phenyl}-10,15,20-triphenylporphyrinatopalladium(II) ([Re(CO)(3)(Pic)Bpy-PdTPP][PF(6)]) have been investigated. The single crystal X-ray structure for the thiocyanate analogue, [Re(CO)(3)(NCS)Bpy-PdTPP], exhibits torsion angles of 69.1(9)°, 178.1(7)°, and 156.8(9)° between porphyrin plane, porphyrin-linked C(6)H(4) group, amide moiety, and Bpy, respectively. Steady-state photoexcitation (λ(ex) = 520 nm) of [Re(CO)(3)(Pic)Bpy-PdTPP][PF(6)] in dimethylformamide (DMF) results in substitution of Pic by bromide at the Re(I)Bpy core. When [Re(CO)(3)(Pic)Bpy-PdTPP][PF(6)] is employed as a photocatalyst for the reduction of CO(2) to CO in DMF/NEt(3) solution with λ(ex) > 420 nm, 2 turnovers (TNs) CO are formed after 4 h. If instead, a two-component mixture of PdTPP sensitizer and mononuclear [Re(CO)(3)(Pic)Bpy][PF(6)] catalyst is used, 3 TNs CO are formed. In each experiment however, CO only forms after a slight induction period and during the concurrent photoreduction of the sensitizer to a Pd(II) chlorin species. Palladium(II) meso-tetraphenylchlorin, the hydrogenated porphyrin analogue of PdTPP, has been synthesized independently and can be substituted for PdTPP in the two-component system with [Re(CO)(3)(Pic)Bpy][PF(6)], forming 9 TNs CO. An intramolecular electron transfer process for the dyad is supported by cyclic voltammetry and steady-state emission studies, from which the free energy change was calculated to be ΔG(ox)* = -0.08 eV. Electron transfer from Pd(II) porphyrin to Re(I) tricarbonyl bipyridine in [Re(CO)(3)(Pic)Bpy-PdTPP][PF(6)] was monitored using time-resolved infrared (TRIR) spectroscopy in the ν(CO) region on several time scales with excitation at 532 nm. Spectra were recorded in CH(2)Cl(2) with and without NEt(3). Picosecond TRIR spectroscopy shows rapid growth of bands assigned to the π-π* excited state (2029 cm(-1)) and to the charge-separated state (2008, 1908 cm(-1)); these bands decay and the parent recovers with lifetimes of 20-50 ps. Spectra recorded on longer time scales (ns, µs, and seconds) show the growth and decay of further species with ν(CO) bands indicative of electron transfer to Re(Bpy).

Platinum(II) terpyridyl acetylide complexes on platinized TiO(2): toward the photogeneration of H(2) in aqueous media.

New platinum(II) terpyridyl acetylide complexes having the ability to bind to TiO(2) have been synthesized and assayed in their ability to sensitize platinized titanium dioxide for the photogeneration of H(2) using visible light (lambda > 410 nm). Specifically, the complexes [Pt(tpy-phen-COOH)(C[triple bond]C-C(6)H(5))]Cl (1), where tpy-phen-COOH = 4'-(4-carboxyphenyl)-[2,2';6',2'']terpyridine and C[triple bond]C-C(6)H(5) = phenylacetylide, and [Pt(tpy-COOH)(C[triple bond]C-C(6)H(5))]Cl (2), where tpy-COOH = 4'-carboxy-2,2';6',2''-terpyridine, were prepared to investigate the effectiveness of attachment and proximity to the TiO(2) surface on hydrogen yield. Both complexes 1 and 2 sensitize the photogeneration of hydrogen, but produce fewer turnovers than the unbound chromophore, [Pt(ttpy)(C[triple bond]C-C(6)H(5))]PF(6) (5). On the basis of these observations and electrochemical data, a major limitation to the effectiveness of these chromophores is their instability upon oxidation. To attempt to remedy this problem, two donor-chromophore (D-C) dyads, [Pt(tpy-phen-COOH)(C[triple bond]C-C(6)H(4)CH(2)-PTZ)]PF(6) (3), where C[triple bond]C-C(6)H(4)CH(2)-PTZ = N-(4-ethynylbenzyl)-phenothiazine and [Pt(tpy-COOH)(C[triple bond]C-C(6)H(4)CH(2)-PTZ)]Cl (4) were prepared to function as TiO(2)-attached sensitizers. Transient absorption measurements have shown that the PTZ moiety reductively quenches the Pt center in several picoseconds. While the resultant PTZ(+) radical cation is capable of oxidizing rapidly the triethanolamine sacrificial electron donor, dyads 3 and 4 attached to platinized TiO(2) do not function to generate hydrogen upon irradiation, in contrast with results seen for 1 and 2.

Cyclometalated 6-phenyl-2,2'-bipyridyl (CNN) platinum(II) acetylide complexes: structure, electrochemistry, photophysics, and oxidative- and reductive-quenching studies.

Three cyclometalated 6-phenyl-4-(p-R-phenyl)-2,2'-bipyridyl (CNN-Ph-R) Pt(II) acetylide complexes, Pt(CNN-Ph-R)(CCPh), where R = Me (1), COOMe (2), and P(O)(OEt)(2) (3), have been synthesized and studied. Compounds 1 and 3 have been structurally characterized by single crystal X-ray crystallography and are found to exhibit distorted square planar geometries about the Pt(II) ions. The electrochemical properties of the compounds, as determined by cyclic voltammetry, have also been examined. Complexes 1-3 are brightly emissive in fluid CH(2)Cl(2) solution and in the solid state with lambda(em)(max) of ca. 600 nm and lifetimes on the order of ca. 500 ns in fluid solution. The emissions are assigned to a (3)MLCT transition. The complexes undergo oxidative quenching by MV(2+) with quenching rates near the diffusion-controlled limit (k(q) approximately 1.4 x 10(10) M(-1) s(-1)) in CH(2)Cl(2) solution. Reductive-quenching experiments of complexes 1-3 by the amine donors N,N,N',N'-tetramethylphenylenediamine (TMPD), phenothiazine (PTZ), and N,N,N',N'-tetramethylbenzidine (TMB) follow Stern-Volmer behavior, with very fast quenching rates on the order of 10(9)-10(10) M(-1) s(-1) in CH(2)Cl(2) solution. When the complexes are employed as the sensitizer in multiple component systems containing MV(2+), TEOA, and colloidal Pt in aqueous media, approximately one turnover of H(2) (TN vs mol of chromophore) is produced per hour upon irradiation with lambda > 410 nm but only after at least a 2 h induction period.

Visible light-driven hydrogen production from aqueous protons catalyzed by molecular cobaloxime catalysts.

A series of cobaloxime complexes([Co(dmgH)(2)pyCl] (1), [Co(dmgH)(2)(4-COOMe-py)Cl] (2), [Co(dmgH)(2)(4-Me(2)N-py)Cl] (3), [Co(dmgH)(dmgH(2))Cl(2)] (4), [Co(dmgH)(2)(py)(2)](PF(6)) (5), [Co(dmgH)(2)(P(n-Bu)(3))Cl] (6), and [Co(dmgBF(2))(2)(OH(2))(2)] (7), where dmgH = dimethylglyoximate monoanion, dmgH(2) = dimethylglyoxime, dmgBF(2) = (difluoroboryl)dimethylglyoximate anion, and py = pyridinewere synthesized and studied as molecular catalysts for the photogeneration of hydrogen from systems containing a Pt terpyridyl acetylide chromophore and triethanolamine (TEOA) as a sacrificial donor in aqueous acetonitrile. All cobaloxime complexes 1-7 are able to quench the luminescence of the Pt(II) chromophore [Pt(ttpy)(CCPh)]ClO(4) (C1) (ttpy = 4'-p-tolyterpyridine). The most effective electron acceptor for hydrogen evolution is found to be complex 2, which provides the fastest luminescence quenching rate constant for C1 of 1.7 x 10(9) M(-1) s(-1). The rate of hydrogen evolution depends on many factors, including the stability of the catalysts, the driving force for proton reduction, the relative and absolute concentrations of system components (TEOA, Co molecular catalyst, and sensitizer), and the ratio of MeCN/water in the reaction medium. For example, when the concentration of TEOA increases, the rate of H(2) photogeneration is faster and the induction period is shorter. Colloidal cobalt experiments and mercury tests were run to verify that the system is homogeneous and that catalysis does not occur from in situ generated colloidal particles during photolysis. The most effective system examined to date consists of the chromophore C1 (1.1 x 10(-5) M), TEOA (0.27 M), and catalyst complex 1 (2.0 x 10(-4) M) in a MeCN/water mixture (24:1 v/v, total 25 mL); this system has produced approximately 2150 turnovers of H(2) after only 10 h of photolysis with lambda > 410 nm.

Platinum(II) terpyridyl-acetylide dyads and triads with nitrophenyl acceptors via a convenient synthesis of a boronated phenylterpyridine.

Four new Pt(II) terpyridyl acetylide complexes which possess a covalently linked nitrophenyl moiety were prepared and studied. Specifically, the chromophore-acceptor (C-A) dyads reported here include [Pt(ptpy-ph-p-NO(2))(C[triple bond]C-C(6)H(5))](PF(6))(3) (1), where ptpy-ph-p-NO(2) = 4'-{4-(4-nitrophenyl)-phenyl}-[2,2';6',2'']terpyridine, and C[triple bond]C-C(6)H(5) = phenylacetylide and [Pt(ptpy-ph-m-NO(2))(C[triple bond]C-C(6)H(5))](PF(6))(2) (2), where ptpy-ph-m-NO(2) = 4'-(4-m-nitrophenyl-phenyl)-2,2';6',2''-terpyridine, as well as the related donor-chromophore-acceptor (D-C-A) triads [Pt(ptpy-ph-p-NO(2))(C[triple bond]C-C(6)H(4)CH(2)-PTZ)]PF(6) (3), where C[triple bond]C-C(6)H(4)CH(2)-PTZ = 4-ethynylbenzyl-N-phenothiazine, and [Pt(ptpy-ph-m-NO(2))(C[triple bond]C-C(6)H(4)CH(2)-PTZ)]PF(6) (4). Transient absorption spectroscopy and electrochemical analyses were used to characterize these compounds. In contrast to previous observations for closely related multicomponent systems, it appears that, in the current systems, the nitrophenyl group is not an effective quencher of the excited state. The luminescence and transient absorption properties of the C-A dyads are virtually identical to those of the parent chromophore, [Pt(ttpy)(C[triple bond]C-C(6)H(5))]PF(6) (5), where ttpy = 4'-p-tolyl-[2,2';6',2'']terpyridine.

Synthesis, electrochemistry, photophysics, and solvatochromism in new cyclometalated 6-phenyl-4-(p-R-phenyl)-2,2'-bipyridyl (R = Me, COOMe, P(O)(OEt)2) (C--N--N) platinum(II) thiophenolate chromophores.

Three new cyclometalated 6-phenyl-4-(p-R-phenyl)-2,2'-bipyridyl (C--N--N) Pt(II) thiophenolate complexes (R = Me (2a), COOMe (2b), and P(O)(OEt)(2) (2c)) have been synthesized and studied. The new C--N--N ligands L2 (R = COOMe) and L3 (R = P(O)(OEt)(2)) undergo cyclometalation with a Pt(II) source to give the Pt(II) chloro complexes 1b and 1c, respectively, which are luminescent in fluid solution with lambda(max) approximately 575 nm, assigned to a metal-to-ligand charge-transfer ((3)MLCT) emissive state. Reaction of the chloro complexes 1a (R = Me), 1b, and 1c with sodium thiophenolate gives 2a-2c, respectively, in good yields. The novel thiophenolate complexes have two interesting absorption bands in their electronic spectra tentatively assigned to a charge-transfer to C--N--N ((1)CT) (lambda(abs) approximately 415 nm) transition and a mixed metal/ligand-to-ligand' charge-transfer (MMLL'CT, lambda(abs) approximately 555 nm) transition, respectively. The MMLL'CT band is solvatochromic with absorption maxima in the range of 496 nm in MeOH to 590 nm in toluene (epsilon approximately 4000 dm(3) mol(-1) cm(-1)), which correlate well with an empirical charge-transfer-based solvent scale. Excitation of 2a-2c into the MMLL'CT band gives emission maxima around 680 nm in frozen CH(2)Cl(2) solution, and no emission in fluid solution. Ligand L2 and complexes 1a.MeCN, 1b, and 2b.CH(2)Cl(2) have been characterized by single crystal X-ray crystallography. The electrochemical properties of ligands L1 (R = Me) and L2 and complexes 1a-1c and 2a-2c have been examined by cyclic voltammetry and are shown to exhibit reversible and quasi-reversible reductions and irreversible oxidations.

Bi- and terpyridyl platinum(II) chloro complexes: molecular catalysts for the photogeneration of hydrogen from water or simply precursors for colloidal platinum?

Platinum(II) bi- and terpyridyl chloro complexes, Pt(dcbpy)Cl2 and [Pt(ttpy)Cl]+, where dcbpy = 4,4'-dicarboxyl-2,2'-bipyridine and ttpy = 4-tolyl-2,2':6',2''-terpyridine, are used to investigate the nature of the active catalyst for the photocatalytic production of hydrogen from water. In a Pt(II) chloro system that contains a sacrificial electron donor, either MeOH or triethanolamine (TEOA), and titanium dioxide (TiO2) as an electron relay, sizable amounts of H2 can be observed upon UV bandgap irradiation. The quantity of H2 can be significantly reduced in the presence of mercury under the same conditions. Using a known sensitizer, [Pt(ttpy)(phenylacetylide)]+ (1), combined with a Pt(II) chloro complex in a similar system, there is a substantial induction period until the evolution of H2, under visible light (lambda > 410 nm) irradiation. It is suggested that the Pt(II) chloro complexes are simply acting as precursors to Pt colloids that function as the H2 generating catalyst

Strong intra- and intermolecular aurophilic interactions in a new series of brilliantly luminescent dinuclear cationic and neutral au(I) benzimidazolethiolate complexes.

The structural and photophysical properties of a new series of cationic and neutral Au(I) dinuclear compounds (1 and 2, respectively) bridged by bis(diphenylphosphino)methane (dppm) and substituted benzimidazolethiolate (X-BIT) ligands, where X = H (a), Me (b), OMe (c), and Cl (d), have been studied. Monocationic complexes, [A(u2)(micro-X-BIT)(micro-dppm)](CF(3)CO(2)), were prepared by the reaction of [A(u2)(micro-dppm)](CF(3)CO(2))(2) with 1 equiv of X-BIT in excellent yields. The cations 1a-1d possess similar molecular structures, each with a linear coordination geometry around the Au(I) nuclei, as well as relatively short intramolecular Au(I)...Au(I) separations ranging between 2.88907(6) A for 1d and 2.90607(16) A for 1a indicative of strong aurophilic interactions. The cations are violet luminescent in CH(2)Cl(2) solution with a lambda(em)(max) of ca. 365 nm, assigned as ligand-based or metal-centered (MC) transitions. Three of the cationic complexes, 1a, 1b, and 1d, exhibit unusual luminescence tribochromism in the solid-state, in which the photoemission is shifted significantly to higher energy upon gentle grinding of microcrystalline samples with DeltaE = 1130 cm(-1) for 1a, 670 cm(-1) (1b), and 870 cm(-1) (1d). The neutral dinuclear complexes, [A(u2)(micro-X-BIT)(micro-dppm)] (2a-2d) were formed in good yields by the treatment of a CH(2)Cl(2) solution of cationic compounds (1) with NEt(3). 2a-2d aggregate to form dimers having substantial intra- and intermolecular aurophilic interactions with unsupported Au(I)...Au(I) intermolecular distances in the range of 2.8793(4)-2.9822(8) A, compared with intramolecular bridge-supported separations of 2.8597(3)-2.9162(3) A. 2a-2d exhibit brilliant luminescence in the solid-state and in DMSO solution with red-shifted lambda(em)(max) energies in the range of 485-545 nm that are dependent on X-BIT and assigned as ligand-to-metal-metal charge transfer (LMMCT) states based in part on the extended Au...Au...Au...Au interactions.

Synthesis and structural characterization of a new vapochromic Pt(II) complex based on the 1-terpyridyl-2,3,4,5,6-pentaphenylbenzene (TPPPB) ligand.

A novel terpyridine ligand containing a pentaphenylphenyl moiety linked to the terpyridyl core (1-terpyridyl-2,3,4,5,6-pentaphenyl-benzene (TPPPB)) has been synthesized in good yield and reacted with Pt(DMSO)2Cl2, to produce the cationic complex [Pt(TPPPB)Cl]Cl (5). 5 was studied structurally and spectroscopically. It is observed to be brightly luminescent in the solid state at room temperature and at 77 K, with no change in lambdaem(max). The complex exhibits reversible vapochromic behavior upon exposure to methylene chloride vapors, changing color from red (5-R) to green (5-G). The shift to higher energy in the emission maximum from 654 to 514 nm is the largest vapochromic shift (140 nm) yet reported. The [Pt(TPPPB)Cl]Cl complex exhibits high selectivity for certain volatile organic compounds (VOCs) including methylene chloride, ethanol, ethyl acetate, and acetonitrile. The crystal structures of both the green and red forms have been determined by single-crystal X-ray diffraction. In both forms, the cationic Pt(II) complex possesses the anticipated square-planar coordination geometry that is distorted as a consequence of constraints from the terpyridyl binding. Analysis of the crystal packing of the green form (5-G) reveals the presence of non-interacting Pt...Pt separations with distances of 3.9092(9) and 4.5483(11) A and a zigzag arrangement between neighboring Pt(II) ions. The red form (5-R) contains complexes that are stacked with Pt...Pt separations of 3.2981(14) and 3.3427(14) A, indicative of metallophilic interaction. The change in the emitting state, as a consequence of the effect of the volatile organic compounds, results from a disruption of the d8-d8 metallophilic interactions in the red form and its metal-metal-to-ligand charge transfer (MMLCT) excited state to a more-localized Pt(dpi)-to-tpy(pi*) metal-to-ligand charge transfer (MLCT) excited state in the green form.

Unifocal langerhans cell histiocytosis presenting with pathological fracture.

A 13-year-old Ethiopian female patient who initially presented with localized pain and minimal soft tissue swelling later developed pathological fracture of the left femnur. The patient was initially treated as a case of osteomyelitis until the diagnosis of Langerhans cell histiocytosis (histiocytosis X, eosiniphilic granuloma) was made by bone biopsy. The clinical presentation of the case and brief review of the literature is discussed.

Photoinduced electron transfer in platinum(II) terpyridyl acetylide chromophores: reductive and oxidative quenching and hydrogen production.

A series of luminescent platinum(II) terpyridyl acetylide complexes, ([Pt(tpy)(CCPh)]ClO4 (1) and [Pt(ttpy)(CC-p-C6H4R)]ClO4, where tpy=terpyridine, ttpy=4'-p-tolylterpyridine, R=H, Cl, Me) (2-4) were studied with regard to excited-state quenching by dialkylated bipyridinium cations as electron acceptors and triethanolamine (TEOA) as an electron donor and the photogeneration of hydrogen from systems containing the chromophore, the dialkylated bipyridinium cations, TEOA, and colloidal Pt as a catalyst. The dialkylated bipyridinium cations include methyl viologen (MV2+) and a series of diquats prepared from 2,2'-bipyridine or 4,4'-dimethyl-2,2'-bipyridine. The quenching rates for the diquats for one of the chromophores (2) are close to the diffusion-controlled limit. The most effective electron acceptor and relay for hydrogen evolution has been found to be 4,4'-dimethyl-1,1'-trimethylene-2,2'-bipyridinium (DQ4) which on photoreduction by the chromohore provides the strongest reducing agent of the diquats studied. The rate of hydrogen evolution depends in a complex way on the concentration of the bipyridinium electron relay, increasing with concentration at low concentrations and then decreasing at high concentrations. The rate of H2 photogeneration also increases with TEOA concentration at low values and eventually reaches a plateau. The most effective system examined to date consists of the chromophore 2 (2.2x10(-5) M), DQ4 (3.1x10(-4) M), TEOA (2.7x10(-2) M), and Pt colloid (6.0x10(-5) M), and has produced 800 turnovers of H2 (67% yield based on TEOA as sacrificial electron donor) after 20 h of photolysis with lambda>410 nm.