A new paradigm is established for the design of conjugated anodically coloring electrochromic molecules. It is shown that through crossconjugation the electronic energy levels of the radical cation ...state may be controllably tuned independent of the neutral state. It is shown how cross-conjugation can be used to tune the radical cation state independent of the neutral state. Manipulating the oscillator strengths of radical cation transitions allows for tuning of the color by shifting the λmax of the low-energy absorption by over 400 nm. The neutral states of these molecules are UV absorbing, providing solutions that are colorless with L*a*b* values of 100, 0, 0. They are oxidized to vibrantly colored radical cations with absorptions that span the visible spectrum, creating green, yellow, and red chromophores. These molecules are then mixed to create transmissive, colorless blends that switch to opaque black solutions.
This work assesses the steric, torsional, and electronic effects of substituents on anodically coloring electrochromic (ACE) molecules to gain insight toward constructing highly transmissive neutral ...states, while attaining vibrant colors in their cation radical and dication states. We examine seven thioalkyl-substituted bis(3,4-ethylenedioxthiophene)-1,4-phenylene (BEDOT-Ph) ACE molecules and compare their optoelectronic, geometric, and excited-state properties. We evaluate their redox properties and show that their first oxidation potential, forming the cation radical, can be varied over 0.70 V, with second oxidations ranging from 0.3 to 0.5 V versus Fc/Fc+. Upon chemical solution doping with Fe(OTf)3, the cation radical states absorb strongly in the visible, providing vibrantly colored solutions, while further oxidation with the stronger oxidant NOPF6 provides evidence for the formation of a dication state. Electrochemical oxidation in an optically transparent thin layer electrode (OTTLE) shows evidence of both the cation radical and the dication states, possibly forming via a disproportionation mechanism. Time-dependent density functional theory (TD-DFT) calculations carried out at the mPW1PBE/cc-PVDZ level are used for the excited state analysis of the neutral and charged states. These model results provide insight into how substituent identity impacts both a high energy absorption localized in the visible region and a lower energy peak that can be moved to the near-infrared region, thereby controlling the color. In tandem with experimental evaluation, we demonstrate how structural design modifications can control both redox and optical properties as a strategy to elucidate color, paving the way for electrochromic applications and fine manipulation of color control.
Peridotites from the thick roots of Archaean cratons are known for their compositional diversity, whose origin remains debated. We report thermodynamic modelling results for reactions between ...peridotite and ascending mantle melts. Reaction between highly magnesian melt (komatiite) and peridotite leads to orthopyroxene crystallisation, yielding silica-rich harzburgite. By contrast, shallow basalt-peridotite reaction leads to olivine enrichment, producing magnesium-rich dunites that cannot be generated by simple melting. Komatiite is spatially and temporally associated with basalt within Archaean terranes indicating that modest-degree melting co-existed with advanced melting. We envisage a relatively cool mantle that experienced episodic hot upwellings, the two settings could have coexisted if roots of nascent cratons became locally strongly extended. Alternatively, deep refractory silica-rich residues could have been detached from shallower dunitic lithosphere prior to cratonic amalgamation. Regardless, the distinct Archaean melting-reaction environments collectively produced skewed and multi-modal olivine distributions in the cratonic lithosphere and bimodal mafic-ultramafic volcanism at surface.
Objective To assess the effectiveness of physiotherapy compared with no intervention in patients with Parkinson’s disease.Design Systematic review and meta-analysis of randomised controlled ...trials.Data sources Literature databases, trial registries, journals, abstract books, and conference proceedings, and reference lists, searched up to the end of January 2012.Review methods Randomised controlled trials comparing physiotherapy with no intervention in patients with Parkinson’s disease were eligible. Two authors independently abstracted data from each trial. Standard meta-analysis methods were used to assess the effectiveness of physiotherapy compared with no intervention. Tests for heterogeneity were used to assess for differences in treatment effect across different physiotherapy interventions used. Outcome measures were gait, functional mobility and balance, falls, clinician rated impairment and disability measures, patient rated quality of life, adverse events, compliance, and economic analysis outcomes.Results 39 trials of 1827 participants met the inclusion criteria, of which 29 trials provided data for the meta-analyses. Significant benefit from physiotherapy was reported for nine of 18 outcomes assessed. Outcomes which may be clinically significant were speed (0.04 m/s, 95% confidence interval 0.02 to 0.06, P<0.001), Berg balance scale (3.71 points, 2.30 to 5.11, P<0.001), and scores on the unified Parkinson’s disease rating scale (total score −6.15 points, −8.57 to −3.73, P<0.001; activities of daily living subscore −1.36, −2.41 to −0.30, P=0.01; motor subscore −5.01, −6.30 to −3.72, P<0.001). Indirect comparisons of the different physiotherapy interventions found no evidence that the treatment effect differed across the interventions for any outcomes assessed, apart from motor subscores on the unified Parkinson’s disease rating scale (in which one trial was found to be the cause of the heterogeneity).Conclusions Physiotherapy has short term benefits in Parkinson’s disease. A wide range of physiotherapy techniques are currently used to treat Parkinson’s disease, with little difference in treatment effects. Large, well designed, randomised controlled trials with improved methodology and reporting are needed to assess the efficacy and cost effectiveness of physiotherapy for treating Parkinson’s disease in the longer term.
A series of conjugated, random terpolymers based on all donor repeat units are prepared via direct (hetero)arylation polymerization yielding cathodically colored electrochromic polymers that span ...the visible spectrum. The polymers are based on repeat units of a dialkylthiophene, a 3,4-propylenedioxythiophene, and dimers of 3,4-ethylenedioxythiophene. Using a tight feedback loop between computational and experimental chemistry, the colors of these polymers are controllably tuned to cover the visible spectrum by controlling the monomer ratios. Examinations via ultraviolet–visible–near-infrared spectroscopy, differential pulse voltammetry, spectroelectrochemistry, and colorimetry show that, while these systems can vary greatly in their spectral properties, their oxidation potentials are all low (<0.5 V vs Ag/AgCl). The color tunability allows for access to neutral state orange, red, pink, magenta, purple, and blue polymers of various hues with a* values ranging from 22 to 35 and b* values ranging from −44 to 45, while maintaining highly transmissive oxidized states. This approach allows access to a wide gamut of colors with only three monomers while affording materials with low oxidation potentials and high contrast.
Atmospherically-fed Earth surface archives such as ombrotrophic peatlands, lake sediments, and ice consistently show an upward increase in Zn concentrations of hitherto unclear origin. Here, we ...present a combined stable Zn isotope and trace element (Zn, Cd, Ni, Cu, Cr, V, Ta, Pb) dataset for a historically polluted, near-urban bog (Liffey Head) from the east coast of Ireland. This peat record is compared to an archive from a rural site at the west coast of Ireland (Brackloon Wood). Both archives show a clear near-surface increase in Zn deposition, accompanied by periodic deposition in Cr, Ni, Mo, and V suggesting a co-genetic origin of these elements. In the Liffey Head site, biologic upward distillation of nutrients can be excluded as the origin of the elemental enrichments. The differences in the excess metal ratios between the two sites (e.g., Zn/Cd of 426–1564, east, and 77–106, west) are attributed to a higher contribution from traffic emissions (diesel, petrol) and oil-burning at the near-urban site, and dominant atmospheric influence from solid fossil fuel combustion emissions (e.g., mixed fuel, coal and wood) at the rural site.
The Zn isotope composition in the historically-polluted Liffey Head bog evolved from δ66/64ZnJMC-Lyon values of 0.72 ± 0.03‰ in the peat accumulated during the 19th century to lighter ratios (0.18 ± 0.03‰) towards the top of the monolith (i.e., recent). Zinc-isotope ratios are positively correlated with excess metal/Cd ratios and also with 206Pb/207Pb, collectively fingerprinting the gradual change from a mining-dominated to a traffic-dominated atmospheric pollution at the east coast over the past century. A prevalent input, interpreted to represent combustion emissions from diesel engines, is observed for the past 15 years. Combined with trace elements and radiogenic Pb isotopes, the information obtained with the Zn isotope systematics adds towards an in-depth characterisation of the pollution signals.
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•Sources of past and recent atmospheric pollution in Ireland are recorded in bogs.•Recent increase in Zn reflects real pollution signal not upward mobility of Zn.•Zn isotopes and metal ratios evidence recent influence from fossil fuel combustion.•Petrol-related pollution can be distinguished from diesel-combustion emissions.•Long-range metal pollution from solid fossil fuels found also at pristine sites.
Accessing conjugated polymers suitable for applications ranging from organic photovoltaics to bioelectronics through simple synthetic protocols is desirable for the conjugated polymer community, as ...many polymer systems that meet device performance metrics require arduous synthetic protocols. To simplify and minimize monomer and polymer synthetic steps, a dibrominated dihydropyrrolopyrrole was synthesized in air using a single synthetic step and did not require column chromatography for purification. Subsequently, the first example of an electron-rich pyrrolopyrrole monomer being polymerized is accomplished via direct arylation polymerization using a dioxythiophene comonomer to access an alternating copolymer in a total of three synthetic steps. The resulting copolymer exhibits absorbance in the high-energy portion of the visible spectrum in solution and the solid state, a relatively low onset of oxidation (∼0.6 V vs Ag/AgCl), and yellow-to-black electrochromism. Finally, the synthetic complexity is calculated, and the pyrrolopyrrole-co-dioxythiophene polymer is less synthetically complex when compared to many conjugated polymers that find applicability in organic photovoltaics and electrochromism. These findings demonstrate the viability of incorporating dihydropyrrolopyrroles into the repeat unit structure of conjugated polymers via metal-catalyzed cross-coupling reactions and highlight their potential to offer a synthetically simple alternative to current state-of-the-art conjugated polymers.
Subtle structural changes in monomeric building blocks can have an immense effect, whether positive or detrimental, on the resulting properties of conjugated polymers. With this in mind, it is ...paramount to understand structure–property relationships that serve as the guiding principles for manipulating optical and electrochemical characteristics. Herein, a family of dialkylthiophene-co-propylenedioxythiophene copolymers are synthesized via direct arylation polymerizations, with a key design motif being minimal changes in the structural composition of the propylenedioxythiophene comonomer. Variation in the substitution pattern on the propylene bridge provides insights into the role of stereo- and compositional isomers on the resulting polymer properties. Specifically, time-dependent density functional theory calculations reveal changes in the number and placement of comonomers with varying composition and stereocenters, impacting the calculated absorbance spectra, as evident from calculated absorbance maxima spanning 75 nm, which ultimately manifests in differences in the calculated color. Experimentally, UV–vis absorbance spectroscopy and colorimetry reveal a dependence on the stereo- and regiospecificity, while electrochromic properties, such as contrast and switching times, are not drastically affected by the substitution patterns. Independent of position and functionality, each polymer exhibited a transmittance change greater than 65% at the maximum absorbance wavelength while maintaining the ability to rapidly switch between colored and transmissive states in organic electrolytes. This work highlights how subtle structural changes can manipulate and optimize optical features without sacrificing electrochromic properties such as kinetic switching time and optical contrast. In addition to fundamental insights into monomeric design of propylenedioxythiophene building blocks and their optical and redox characteristics, the results provide an additional structural handle for fine-tuning the observed color of electrochromic polymers.
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