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We collected 1 year of aerosol chemical speciation monitor (ACSM) data in Magadino, a village located in the south of the Swiss Alpine region, one of Switzerland's most polluted areas. We analysed the mass spectra of organic aerosol (OA) by positive matrix factorisation (PMF) using Source Finder Professional (SoFi Pro) to retrieve the origins of OA. Therein, we deployed a rolling algorithm, which is closer to the measurement, to account for the temporal changes in the source profiles. As the first-ever application of rolling PMF with multilinear engine (ME-2) analysis on a yearlong dataset that was collected from a rural site, we resolved two primary OA factors (traffic-related hydrocarbon-like OA (HOA) and biomass burning OA (BBOA)), one mass-to-charge ratio (m/z) 58-related OA (58-OA) factor, a less oxidised oxygenated OA (LO-OOA) factor, and a more oxidised oxygenated OA (MO-OOA) factor. HOA showed stable contributions to the total OA through the whole year ranging from 8.1 % to 10.1 %, while the contribution of BBOA showed an apparent seasonal variation with a range of 8.3 %–27.4 % (highest during winter, lowest during summer) and a yearly average of 17.1 %. OOA (sum of LO-OOA and MO-OOA) contributed 71.6 % of the OA mass, varying from 62.5 % (in winter) to 78 % (in spring and summer). The 58-OA factor mainly contained nitrogen-related variables which appeared to be pronounced only after the filament switched. However, since the contribution of this factor was insignificant (2.1 %), we did not attempt to interpolate its potential source in this work. The uncertainties (σ) for the modelled OA factors (i.e. rotational uncertainty and statistical variability in the sources) varied from ±4 % (58-OA) to a maximum of ±40 % (LO-OOA). Considering that BBOA and LO-OOA (showing influences of biomass burning in winter) had significant contributions to the total OA mass, we suggest reducing and controlling biomass-burning-related residential heating as a mitigation strategy for better air quality and lower PM levels in this region or similar locations. In Appendix A, we conduct a head-to-head comparison between the conventional seasonal PMF analysis and the rolling mechanism. We find similar or slightly improved results in terms of mass concentrations, correlations with external tracers, and factor profiles of the constrained POA factors. The rolling results show smaller scaled residuals and enhanced correlations between OOA factors and corresponding inorganic salts compared to those of the seasonal solutions, which was most likely because the rolling PMF analysis can capture the temporal variations in the oxidation processes for OOA components. Specifically, the time-dependent factor profiles of MO-OOA and LO-OOA can well explain the temporal viabilities of two main ions for OOA factors, m/z 44 (CO2+) and m/z 43 (mostly C2H3O+). Therefore, this rolling PMF analysis provides a more realistic source apportionment (SA) solution with time-dependent OA sources. The rolling results also show good agreement with offline Aerodyne aerosol mass spectrometer (AMS) SA results from filter samples, except for in winter. The latter discrepancy is likely because the online measurement can capture the fast oxidation processes of biomass burning sources, in contrast to the 24 h filter samples. This study demonstrates the strengths of the rolling mechanism, provides a comprehensive criterion list for ACSM users to obtain reproducible SA results, and is a role model for similar analyses of such worldwide available data.

The measurement of elements in PM10 was performed with 1 h time resolution at a rural freeway site during summer 2015 in Switzerland using the Xact1 625 Ambient Metals Monitor. On average the Xact elements (without accounting for oxygen and other associated elements) make up about 20 % of the total PM10 mass (14.6 µg m−3). We conducted source apportionment by positive matrix factorisation (PMF) of the elemental mass measurable by the Xact (i.e. major elements heavier than Al), defined here as PM10el. Eight different sources were identified in PM10el (elemental PM10) mass driven by the sum of 14 elements (notable elements in brackets): Fireworks-I (K, S, Ba and Cl), Fireworks-II (K), sea salt (Cl), secondary sulfate (S), background dust (Si, Ti), road dust (Ca), non-exhaust traffic-related elements (Fe) and industrial elements (Zn and Pb). The major components were secondary sulfate and non-exhaust traffic-related elements followed by background dust and road dust factors, explaining 21 %, 20 %, 18 % and 16 % of the analysed PM10 elemental mass, respectively, with the factor mass not corrected for oxygen content. Further, there were minor contributions (on the order of a few percent) of sea salt and industrial sources. The regionally influenced secondary sulfate factor showed negligible resuspension, and concentrations were similar throughout the day. The significant loads of the non-exhaust traffic-related and road dust factors with strong diurnal variations highlight the continuing importance of vehicle-related air pollutants at this site. Enhanced control of PMF implemented via the SourceFinder software (SoFi Pro version 6.2, PSI, Switzerland) allowed for a successful apportionment of transient sources such as the two firework factors and sea salt, which remained mixed when analysed by unconstrained PMF.

Reactive oxygen species (ROS) are believed to contribute to the adverse health effects of aerosols. This may happen by inhaled particle-bound (exogenic) ROS (PB-ROS) or by ROS formed within the respiratory tract by certain aerosol components (endogenic ROS). We investigated the chemical composition of aerosols and their exogenic ROS content at the two contrasting locations Beijing (China) and Bern (Switzerland). We apportioned the ambient organic aerosol to different sources and attributed the observed water-soluble PB-ROS to them. The oxygenated organic aerosol (OOA, a proxy for secondary organic aerosol, SOA) explained the highest fraction of the exogenic ROS concentration variance at both locations. We also characterized primary and secondary aerosol emissions generated from different biogenic and anthropogenic sources in smog chamber experiments. The exogenic PB-ROS content in the OOA from these emission sources was comparable to that in the ambient measurements. Our results imply that SOA from gaseous precursors of different anthropogenic emission sources is a crucial source of water-soluble PB-ROS and should be additionally considered in toxicological and epidemiological studies in an adequate way besides primary emissions. The importance of PB-ROS may be connected to the seasonal trends in health effects of PM reported by epidemiological studies, with elevated incidences of adverse effects in warmer seasons, which are accompanied by more-intense atmospheric oxidation processes.

Particulate matter (PM) pollution is a severe environmental problem in the Beijing–Tianjin–Hebei (BTH) region in North China. PM studies have been conducted extensively in Beijing, but the chemical composition, sources, and atmospheric processes of PM are still relatively less known in nearby Tianjin and Hebei. In this study, fine PM in urban Shijiazhuang (the capital of Hebei Province) was characterized using an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) from 11 January to 18 February in 2014. The average mass concentration of non-refractory submicron PM (diameter  µm, NR-PM1) was 178±101 µg m−3, and it was composed of 50 % organic aerosol (OA), 21 % sulfate, 12 % nitrate, 11 % ammonium, and 6 % chloride. Using the multilinear engine (ME-2) receptor model, five OA sources were identified and quantified, including hydrocarbon-like OA from vehicle emissions (HOA, 13 %), cooking OA (COA, 16 %), biomass burning OA (BBOA, 17 %), coal combustion OA (CCOA, 27 %), and oxygenated OA (OOA, 27 %). We found that secondary formation contributed substantially to PM in episodic events, whereas primary emissions were dominant (most significant) on average. The episodic events with the highest NR-PM1 mass range of 300–360 µg m−3 were comprised of 55 % of secondary species. On the contrary, a campaign-average low OOA fraction (27 %) in OA indicated the importance of primary emissions, and a low sulfur oxidation degree (FSO4) of 0.18 even at RH >90 % hinted at insufficient oxidation. These results suggested that in Shijiazhuang in wintertime fine PM was mostly from primary emissions without sufficient atmospheric aging, indicating opportunities for air quality improvement by mitigating direct emissions. In addition, secondary inorganic and organic (OOA) species dominated in pollution events with high-RH conditions, most likely due to enhanced aqueous-phase chemistry, whereas primary organic aerosol (POA) dominated in pollution events with low-RH and stagnant conditions. These results also highlighted the importance of meteorological conditions for PM pollution in this highly polluted city in North China.

Similarities and differences in the submicron atmospheric aerosol chemical composition are analyzed from a unique set of measurements performed at 21 sites across Europe for at least one year. These sites are located between 35 and 62°N and 10° W – 26°E, and represent various types of settings (remote, coastal, rural, industrial, urban). Measurements were all carried out on-line with a 30-min time resolution using mass spectroscopy based instruments known as Aerosol Chemical Speciation Monitors (ACSM) and Aerosol Mass Spectrometers (AMS) and following common measurement guidelines. Data regarding organics, sulfate, nitrate and ammonium concentrations, as well as the sum of them called non-refractory submicron aerosol mass concentration ([NR-PM1]) are discussed. NR-PM1 concentrations generally increase from remote to urban sites. They are mostly larger in the mid-latitude band than in southern and northern Europe. On average, organics account for the major part (36–64%) of NR-PM1 followed by sulfate (12–44%) and nitrate (6–35%). The annual mean chemical composition of NR-PM1 at rural (or regional background) sites and urban background sites are very similar. Considering rural and regional background sites only, nitrate contribution is higher and sulfate contribution is lower in mid-latitude Europe compared to northern and southern Europe. Large seasonal variations in concentrations (μg/m³) of one or more components of NR-PM1 can be observed at all sites, as well as in the chemical composition of NR-PM1 (%) at most sites. Significant diel cycles in the contribution to [NR-PM1] of organics, sulfate, and nitrate can be observed at a majority of sites both in winter and summer. Early morning minima in organics in concomitance with maxima in nitrate are common features at regional and urban background sites. Daily variations are much smaller at a number of coastal and rural sites. Looking at NR-PM1 chemical composition as a function of NR-PM1 mass concentration reveals that although organics account for the major fraction of NR-PM1 at all concentration levels at most sites, nitrate contribution generally increases with NR-PM1 mass concentration and predominates when NR-PM1 mass concentrations exceed 40 μg/m³ at half of the sites.

Aerosol–cloud interactions (ACI) constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN). Here we present a data set – ready to be used for model validation – of long-term observations of CCN number concentrations, particle number size distributions and chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural background, alpine sites, remote forests and an urban surrounding. Expectedly, CCN characteristics are highly variable across site categories. However, they also vary within them, most strongly in the coastal background group, where CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behaviour, most continental stations exhibit very similar activation ratios (relative to particles > 20 nm) across the range of 0.1 to 1.0 % supersaturation. At the coastal sites the transition from particles being CCN inactive to becoming CCN active occurs over a wider range of the supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g. at Barrow (Arctic haze in spring), at the alpine stations (stronger influence of polluted boundary layer air masses in summer), the rain forest (wet and dry season) or Finokalia (wildfire influence in autumn). The rural background and urban sites exhibit relatively little variability throughout the year, while short-term variability can be high especially at the urban site. The average hygroscopicity parameter, κ, calculated from the chemical composition of submicron particles was highest at the coastal site of Mace Head (0.6) and lowest at the rain forest station ATTO (0.2–0.3). We performed closure studies based on κ–Köhler theory to predict CCN number concentrations. The ratio of predicted to measured CCN concentrations is between 0.87 and 1.4 for five different types of κ. The temporal variability is also well captured, with Pearson correlation coefficients exceeding 0.87. Information on CCN number concentrations at many locations is important to better characterise ACI and their radiative forcing. But long-term comprehensive aerosol particle characterisations are labour intensive and costly. Hence, we recommend operating migrating-CCNCs to conduct collocated CCN number concentration and particle number size distribution measurements at individual locations throughout one year at least to derive a seasonally resolved hygroscopicity parameter. This way, CCN number concentrations can only be calculated based on continued particle number size distribution information and greater spatial coverage of long-term measurements can be achieved.

The Xact 625 Ambient Metals Monitor was tested during a 3-week field campaign at the rural, traffic-influenced site Härkingen in Switzerland during the summer of 2015. The field campaign encompassed the Swiss National Day fireworks event, providing increased concentrations and unique chemical signatures compared to non-fireworks (or background) periods. The objective was to evaluate the data quality by intercomparison with other independent measurements and test its applicability for aerosol source quantification. The Xact was configured to measure 24 elements in PM10 with 1 h time resolution. Data quality was evaluated for 10 24 h averages of Xact data by intercomparison with 24 h PM10 filter data analysed with ICP-OES for major elements, ICP-MS for trace elements, and gold amalgamation atomic absorption spectrometry for Hg. Ten elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, Ba, Pb) showed excellent correlation between the compared methods, with r2 values ≥ 0.95. However, the slopes of the regressions between Xact 625 and ICP data varied from 0.97 to 1.8 (average 1.28) and thus indicated generally higher Xact elemental concentrations than ICP for these elements. Possible reasons for these differences are discussed, but further investigations are needed. For the remaining elements no conclusions could be drawn about their quantification for various reasons, mainly detection limit issues. An indirect intercomparison of hourly values was performed for the fireworks peak, which brought good agreement of total masses when the Xact data were corrected with the regressions from the 24 h value intercomparison. The results demonstrate that multi-metal characterization at high-time-resolution capability of Xact is a valuable and practical tool for ambient monitoring.

Mass spectrometric measurements commonly yield data on hundreds of variables over thousands of points in time. Refining and synthesizing this raw data into chemical information necessitates the use of advanced, statistics-based data analytical techniques. In the field of analytical aerosol chemistry, statistical, dimensionality reductive methods have become widespread in the last decade, yet comparable advanced chemometric techniques for data classification and identification remain marginal. Here we present an example of combining data dimensionality reduction (factorization) with exploratory classification (clustering), and show that the results cannot only reproduce and corroborate earlier findings, but also complement and broaden our current perspectives on aerosol chemical classification. We find that applying positive matrix factorization to extract spectral characteristics of the organic component of air pollution plumes, together with an unsupervised clustering algorithm, k-means+ + , for classification, reproduces classical organic aerosol speciation schemes. Applying appropriately chosen metrics for spectral dissimilarity along with optimized data weighting, the source-specific pollution characteristics can be statistically resolved even for spectrally very similar aerosol types, such as different combustion-related anthropogenic aerosol species and atmospheric aerosols with similar degree of oxidation. In addition to the typical oxidation level and source-driven aerosol classification, we were also able to classify and characterize outlier groups that would likely be disregarded in a more conventional analysis. Evaluating solution quality for the classification also provides means to assess the performance of mass spectral similarity metrics and optimize weighting for mass spectral variables. This facilitates algorithm-based evaluation of aerosol spectra, which may prove invaluable for future development of automatic methods for spectra identification and classification. Robust, statistics-based results and data visualizations also provide important clues to a human analyst on the existence and chemical interpretation of data structures. Applying these methods to a test set of data, aerosol mass spectrometric data of organic aerosol from a boreal forest site, yielded five to seven different recurring pollution types from various sources, including traffic, cooking, biomass burning and nearby sawmills. Additionally, three distinct, minor pollution types were discovered and identified as amine-dominated aerosols.

Fine particulate matter (PM) levels and resulting impacts on human health are in the Po Valley (Italy) among the highest in Europe. To build effective PM abatement strategies, it is necessary to characterize fine PM chemical composition, sources and atmospheric processes on long timescales (> months), with short time resolution (1) with a time resolution of 30 min at the regional background site of Ispra during 1 full year, using the Aerodyne Aerosol Chemical Speciation Monitor (ACSM) under the most up-to-date and stringent quality assurance protocol. The identification of the main components of the organic fraction is made using the Multilinear-Engine 2 algorithm implemented within the latest version of the SoFi toolkit. In addition, with the aim of a potential implementation of ACSM measurements in European air quality networks as a replacement of traditional filter-based techniques, parallel multiple offline analyses were carried out to assess the performance of the ACSM in the determination of PM chemical species regulated by air quality directives. The annual NR-PM1 level monitored at the study site (14.2 µg m−3) is among the highest in Europe and is even comparable to levels reported in urban areas like New York City and Tokyo. On the annual basis, submicron particles are primarily composed of organic aerosol (OA, 58 % of NR-PM1). This fraction was apportioned into oxygenated OA (OOA, 66 %), hydrocarbon-like OA (HOA, 11 % of OA) and biomass burning OA (BBOA, 23 %). Among the primary sources of OA, biomass burning (23 %) is thus bigger than fossil fuel combustion (11 %). Significant contributions of aged secondary organic aerosol (OOA) are observed throughout the year. The unexpectedly high degree of oxygenation estimated during wintertime is probably due to the contribution of secondary BBOA and the enhancement of aqueous-phase production of OOA during cold months. BBOA and nitrate are the only components of which contributions increase with the NR-PM1 levels. Therefore, biomass burning and NOx emission reductions would be particularly efficient in limiting submicron aerosol pollution events. Abatement strategies conducted during cold seasons appear to be more efficient than annual-based policies. In a broader context, further studies using high-time-resolution analytical techniques on a long-term basis for the characterization of fine aerosol should help better shape our future air quality policies, which constantly need refinement.

In early spring the Baltic region is frequently affected by high-pollution events due to biomass burning in that area. Here we present a comprehensive study to investigate the impact of biomass/grass burning (BB) on the evolution and composition of aerosol in Preila, Lithuania, during springtime open fires. Non-refractory submicron particulate matter (NR-PM1) was measured by an Aerodyne aerosol chemical speciation monitor (ACSM) and a source apportionment with the multilinear engine (ME-2) running the positive matrix factorization (PMF) model was applied to the organic aerosol fraction to investigate the impact of biomass/grass burning. Satellite observations over regions of biomass burning activity supported the results and identification of air mass transport to the area of investigation. Sharp increases in biomass burning tracers, such as levoglucosan up to 683 ng m−3 and black carbon (BC) up to 17 µg m−3 were observed during this period. A further separation between fossil and non-fossil primary and secondary contributions was obtained by coupling ACSM PMF results and radiocarbon (14C) measurements of the elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon (OCnf) was the dominant fraction of PM1, with the primary (POCnf) and secondary (SOCnf) fractions contributing 26–44 % and 13–23 % to the total carbon (TC), respectively. 5–8 % of the TC had a primary fossil origin (POCf), whereas the contribution of fossil secondary organic carbon (SOCf) was 4–13 %. Non-fossil EC (ECnf) and fossil EC (ECf) ranged from 13–24 and 7–13 %, respectively. Isotope ratios of stable carbon and nitrogen isotopes were used to distinguish aerosol particles associated with solid and liquid fossil fuel burning.

As part of the European ACTRIS project, the first large Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM) intercomparison study was conducted in the region of Paris for 3 weeks during the late-fall – early-winter period (November–December 2013). The first week was dedicated to the tuning and calibration of each instrument, whereas the second and third were dedicated to side-by-side comparison in ambient conditions with co-located instruments providing independent information on submicron aerosol optical, physical, and chemical properties. Near real-time measurements of the major chemical species (organic matter, sulfate, nitrate, ammonium, and chloride) in the non-refractory submicron aerosols (NR-PM1) were obtained here from 13 Q-ACSM. The results show that these instruments can produce highly comparable and robust measurements of the NR-PM1 total mass and its major components. Taking the median of the 13 Q-ACSM as a reference for this study, strong correlations (r2 > 0.9) were observed systematically for each individual Q-ACSM across all chemical families except for chloride for which three Q-ACSMs showing weak correlations partly due to the very low concentrations during the study. Reproducibility expanded uncertainties of Q-ACSM concentration measurements were determined using appropriate methodologies defined by the International Standard Organization (ISO 17025, 1999) and were found to be 9, 15, 19, 28, and 36 % for NR-PM1, nitrate, organic matter, sulfate, and ammonium, respectively. However, discrepancies were observed in the relative concentrations of the constituent mass fragments for each chemical component. In particular, significant differences were observed for the organic fragment at mass-to-charge ratio 44, which is a key parameter describing the oxidation state of organic aerosol. Following this first major intercomparison exercise of a large number of Q-ACSMs, detailed intercomparison results are presented, along with a discussion of some recommendations about best calibration practices, standardized data processing, and data treatment.

Chemically resolved (organic, nitrate, sulfate, ammonium) data of non-refractory submicron (NR-PM1) aerosol from the first long-term deployment (27 July 2012 to 02 October 2013) of a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) at the Swiss high-altitude site Jungfraujoch (JFJ; 3580 m a.s.l.) are presented. Besides total mass loadings, diurnal variations and relative species contributions during the different meteorological seasons, geographical origin and sources of organic aerosol (OA) are discussed. Backward transport simulations show that the highest (especially sulfate) concentrations of NR-PM1 were measured in air masses advected to the station from regions south of the JFJ, while lowest concentrations were seen from western regions. OA source apportionment for each season was performed using the Source Finder (SoFi) interface for the multilinear engine (ME-2). OA was dominated in all seasons by oxygenated OA (OOA, 71–88 %), with lesser contributions from local tourism-related activities (7–12 %) and hydrocarbon-like OA related to regional vertical transport (3–9 %). In summer the OOA can be separated into a background low-volatility OA (LV-OOA I, possibly associated with long-range transport) and a slightly less oxidised low-volatility OA (LV-OOA II) associated with regional vertical transport. Wood burning-related OA associated with regional transport was detected during the whole winter 2012/2013 and during rare events in summer 2013, in the latter case attributed to small-scale transport for the surrounding valleys. Additionally, the data were divided into periods with free tropospheric (FT) conditions and periods with planetary boundary layer (PBL) influence, enabling the assessment of the composition for each. Most nitrate and part of the OA are injected from the regional PBL, while sulfate is mainly produced in the FT. The south/north gradient of sulfate is also pronounced in FT air masses (sulfate mass fraction from the south: 45 %; from the north: 29 %). Furthermore, a detailed investigation of specific marker fragments of the OA spectra (f43, f44, f55, f57, f60) showed different degrees of ageing depending on season.

Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSMs) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about 3 weeks in November and December~2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of mass-to-charge ratio m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). ME-2 boundary conditions (profile constraints) were optimised individually by means of correlation to external data in order to achieve equivalent / comparable solutions for all ACSM instruments and the results are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative standard deviations (SD) from the mean between 13.7 and 22.7 % of the source's average mass contribution depending on the factors (HOA: 14.3 ± 2.2 %, COA: 15.0 ± 3.4 %, OOA: 41.5 ± 5.7 %, BBOA: 29.3 ± 5.0 %). Factors which tend to be subject to minor factor mixing (in this case COA) have higher relative uncertainties than factors which are recognised more readily like the OOA. Averaged over all factors and instruments the relative first SD from the mean of a source extracted with ME-2 was 17.2 %.

We present a new instrument for monitoring aerosol composition, the time-of-flight aerosol chemical speciation monitor (ToF-ACSM), combining precision state-of-the-art time-of-flight mass spectrometry with stability, reliability, and easy handling, which are necessities for long-term monitoring operations on the scale of months to years. Based on Aerodyne aerosol mass spectrometer (AMS) technology, the ToF-ACSM provides continuous online measurements of chemical composition and mass of non-refractory submicron aerosol particles. In contrast to the larger AMS, the compact-sized and lower-priced ToF-ACSM does not feature particle sizing, similar to the widely-used quadrupole-ACSM (Q-ACSM). Compared to the Q-ACSM, the ToF-ACSM features a better mass resolution of M/ΔM = 600 and better detection limits on the order of < 30 ng m−3 for a time resolution of 30 min. With simple upgrades these limits can be brought down by another factor of ~ 8. This allows for operation at higher time resolutions and in low concentration environments. The associated software packages (single packages for integrated operation and calibration and analysis) provide a high degree of automation and remote access, minimising the need for trained personnel on site. Intercomparisons with Q-ACSM, C-ToF-AMS, nephelometer and scanning mobility particle sizer (SMPS) measurements, performed during a first long-term deployment (> 10 months) on the Jungfraujoch mountain ridge (3580 m a.s.l.) in the Swiss Alps, agree quantitatively. Additionally, the mass resolution of the ToF-ACSM is sufficient for basic mass defect resolved peak fitting of the recorded spectra, providing a data stream not accessible to the Q-ACSM. This allows for quantification of certain hydrocarbon and oxygenated fragments (e.g. C3H7+ and C2H3O+, both occurring at m/Q = 43 Th), as well as improving inorganic/organic separation.

TbB3O6, that suffers peritectic decomposition below its melting point, was obtained as single crystals by growth from borate flux. Depending on the borate flux, orthorhombic space group Pnma TbB3O6belonging to the isomorphic series of rare earth triborates with small lanthanides, or monoclinic space group C2c TbB3O6, belonging the corresponding isomorphic series with large lanthanides, was synthesized. Within a broad range at subambient temperatures monoclinic TbB3O6shows a structural phase transition with a large thermal hysteresis. The phase transition was characterised by means of differential scanning calorimetry, temperaturedependent polarization microscopy and singlecrystal Xray diffraction. According to the observed features the transition can be classified as a nonferroic, martensitic phase transformation. © 2008 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim [ABSTRACT FROM AUTHOR]

The Group IV bent metallocenes Cp2M (M = Ti, Zr, Hf) were involved in carbene-related chemistry in various ways. Examples from four different areas are used to illustrate this. In situ generated Cp2M: species exhibit some carbene-like character. They add to olefins, and their addition products can incorporate additional unsaturated organic reagents, e.g., alkyne, to form five-membered metallacycles. The high oxophilicity of the Group IV metals helps the addition of alkene-, aryne-, η2-ketone-, η2-aldehyde-, or butadiene-containing reagents to a great variety of metal carbonyl compounds to form the Fischer-type carbene complexes. The resulting zirconoxycarbene complexes have found some application in organometallic chemistry and in organic synthesis. Reactive [Cp2MIVR]+ cations can be stabilized by the addition of the Arduengo carbenes that serve as bulky two-electron donor ligands. First examples were structurally characterized. Dialkylimidazol-2-ylidenes also add to the electrophilic MX4 compounds yielding stable trans-bis(imidazol-2-ylidene)MX4 systems. Several examples are presented where ruthenium carbene complexes are used for carrying out catalytic olefin metathesis reactions at pendant olefinic substituents at the bent metallocenes. These reactions have led to the formation of novel bimetallic metallocene systems, as well as to new ansa-metallocenes. These catalytic reactions have helped in the current efforts to develop a functional group chemistry at the sensitive Group IV bent metallocene frameworks. [ABSTRACT FROM AUTHOR]

Charged molecules play essential roles in many natural and artificial functional processes, ranging from photosynthesis to photovoltaics to chemical reactions and more. It is often difficult to identify the optical dynamic properties of relevant redox species because they cannot be easily prepared, their spectra overlap, or they evolve on a femtosecond timescale. Here, we address these challenges by combining spectroelectrochemistry, ultrafast transient absorption spectroscopy, and suitable data analysis. We illustrate the method with the various redox species of a cyclophane composed of two perylene bisimide subunits. While singular-value decomposition is a well-established tool in the analysis of time-dependent spectra of a single molecular species, we here use it additionally to separate transient maps of individual redox species. This is relevant because at any specific applied electrochemical potential, several redox species coexist in the ensemble, and our procedure allows disentangling their spectroscopic response. In the second step, global analysis is then employed to retrieve the excited-state lifetimes and decay-associated difference spectra. Our approach is generally suitable for unraveling ultrafast dynamics in materials featuring charge-transfer processes., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Reliable structure elucidation of covalent organic cage compounds remains challenging as routine analysis might leave ambiguities. Diffusion-ordered NMR spectroscopy (DOSY) allows insight into the molecular size and mass of the species present in solution, but a systematic evaluation of the diffusion behavior for cage assemblies is rarely considered. Here we report the synthesis of four series of covalent organic cages based on tribenzotriquinacenes and diboronic acids with varying geometry and exohedral substituents. We provide a guideline for the consistent measurement of diffusion coefficients from 1 H-DOSY NMR spectroscopy, which was utilized to study the diffusion behavior for the whole set of cages and selected examples from the literature. For structurally similar cages, a linear correlation between the solvodynamic volume and the molecular mass allows precise size determination. For more complex systems, multiple parameters, such as window size or rigid exohedral functionalization. further modulate cage diffusion in solution., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Objectives: Less than 1 % of patients with Lyme Neuroborreliosis (LNB) present with a cerebrovascular event. Ischaemic strokes occur more commonly than parenchymal or subarachnoid haemorrhages. If cerebral vasculitis due to LNB is suspected, antibiotic treatment should be started immediately, which will normally lead to remission. Very rarely progression and recurrent strokes are observed despite sufficient antibiotic therapy, even if steroids are added. Currently there are no guidelines on the adequate treatment of cerebral vasculitis due to LNB which is not responsive to antibiotics and steroids, but in very few reported cases cyclophosphamide led to disease stabilisation. We reviewed the literature regarding cyclophosphamide treatment in these patients and want to share our experience of cyclophosphamide therapy in progressive cerebral vasculitis due to LNB., Results: We report a 71-year-old female patient with cerebral vasculitis and multiple strokes as a complication of LNB. Progression could only be halted by additional immunosuppressive treatment using cyclophosphamide. However, at that point the patient had already suffered severe ischaemic brain damage. Similarly, in existing case reports cyclophosphamide had been administered only at a time when patients already showed serious neurological deficits., Conclusion: Cerebral vasculitis in patients with LNB is very rare and normally responds to antibiotic treatment. A minority of patients show disease progression despite antibiotics and steroids. Our case report strengthens the recommendation that in those patients - even if signs of progressive vasculitis are only detectable on imaging and not clinically - cyclophosphamide should be considered without delay to prevent further cerebrovascular events., Competing Interests: Declaration of Competing Interest 1. Conflicting interests The Authors declare that there is no conflict of interest. 2. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. 3. Informed consent Written informed consent from the patient´s legal guardian has been obtained., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Perylene bisimides are widely studied due to their various applications. Most research is carried out on neutral molecules but charged species are essential in the context of organic electronics and photovoltaics. In this study, we carry out ultrafast transient absorption spectroelectrochemistry and coherent two-dimensional electronic spectroelectrochemistry on three different neutral perylene bisimide derivatives as well as their singly and doubly reduced species. We compare an unsubstituted, flat parent perylene bisimide with two twisted ones that introduce spin-orbit coupling, leading to enhanced intersystem crossing. The internal conversion from higher excited states to the lowest electronically excited state occurs in the picosecond regime with lifetimes significantly shorter for the charged species compared to the neutral ones. Coherent oscillations of the transients for the flat dianion of parent perylene bisimide indicate the occurrence of Fermi resonance. The corresponding vibrational coupling and the superposition of the participating vibrational modes may lead to an enhanced charge separation and triplet formation.

Negative allosteric modulators of N-methyl- d-aspartate receptors containing the GluN2B subunit represent promising drug candidates for the treatment of various neurological disorders including stroke, epilepsy, and Parkinson's disease. To increase the bioavailability and GluN2B affinity, the phenol of the potent benzazepine-based inhibitor, WMS-1410 (3), was replaced bioisosterically by a benzoxazolone moiety and the phenylbutyl side chain was conformationally restricted in a phenylcyclohexyl substituent. A four-step, one-pot procedure transformed the oxazolo-benzazepine 7 into the phenylcyclohexyl derivative 11. The same protocol was applied to the methylated analog 12, which unexpectedly led to ring-contracted oxazolo-isoquinolines 18. This rearrangement was explained by the additional methyl moiety in the 8-position inhibiting the formation of the planar intermediate iminium ion with phenylcyclohexanone. The allyl protective group of 11 and 18 was removed with RhCl 3 and HCl to obtain the tricyclic compounds 5 and 19 without substituent at the oxazolone ring. The structures of the rearranged products 18 and 19 were elucidated by X-ray crystal structure analysis. The oxazolo-isoquinoline trans-18 with allyl moiety (K i  = 89 nM) and the oxazolo-benzazepine 5 without substituent at the oxazolone ring (K i  = 114 nM) showed GluN2B affinity in the same range as the lead compound 3. In two-electrode voltage clamp measurements, 5 displayed only weak inhibitory activity., (© 2022 The Authors. Archiv der Pharmazie published by Wiley-VCH GmbH on behalf of Deutsche Pharmazeutische Gesellschaft.)

The rate of transvenous lead extraction (TLE) is increasing, with an increasing rate of complex devices being implanted. TLE is now a routine part of cardiac device management and up-to-date data on the safety and efficacy of TLE with modern tools and techniques is essential to management decisions regarding noninfectious indications for lead extraction. We present a contemporary, prospective review of TLE at our high-volume cardiac center. All patients who underwent TLE from June 2016 to June 2019 were enrolled in our local database, and baseline clinical data, procedural information, and outcome data were collected. In total, 561 leads were explanted (n = 153) or extracted (n = 408) from 341 patients over the study period. Patients were predominantly male (71%), with a mean age of 65 ± 17 years. The most common indication for lead removal was lead failure (45.2%, n = 154), followed by infection of the pocket or device (29.3%, n = 100). In total, complete success was achieved in 96.4% (n = 541) leads, clinical success in a further 2.1% (n = 12), and failure only in 1.4% (n = 8). There was an overall complication rate of 0.9% (3/341) for major complications and 1.5% (5/341) for minor complications. There were no deaths. In conclusion, our data suggest that there are ongoing improvements in the safety profile and success rates of lead extraction undertaken by experienced operators. The major complication rate now is <1%., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: The diagnosis of device infections, especially pocket infections, is challenging and relies primarily on clinical presentation. The prospective DIRT (Device associated Infections Role of new diagnostic Tools) study identified procalcitonin (PCT) as the most promising biomarker among other 14 biomarkers to aid the diagnosis of pocket infection. It also identified an optimized cut-off value of 0.05 ng/ml for a localized generator pocket infection., Aims: The present study aims to validate the proposed PCT cut-off value of 0.05 ng/ml for the diagnosis of pocket infection in an independent cohort., Methods: We prospectively enrolled 81 patients with pocket infections and 81 controls matched for age and renal function presenting for elective device exchange or lead revision. Patients with concomitant infectious or inflammatory diseases, end-stage renal failure, current active malignancy, or receiving immunosuppressive therapy were excluded., Results: An elevated PCT over 0.05 ng/ml was found in 68% (n = 55) of pocket infections and 24% (n = 19) of controls, corresponding to a sensitivity of 68% and a specificity of 77% for diagnosing a pocket infection. In receiver operating characteristic (ROC) analysis, PCT showed an area under the curve of 0.75 (95% confidence interval, 0.68-0.83; P < 0.001). Sensitivity remained high with antibiotic pretreatment (65% compared to 69% without pretreatment) and in cases with minimal inflammatory signs (67% compared to 70% with extensive inflammation)., Conclusion: Our study validates the cut-off value of 0.05 ng/ml PCT for diagnosis of a pocket infection, even in patients pre-treated with antibiotics or with minimal clinical signs of inflammation.

A family of neutral bis-cyclometalated Ir(III) complexes based on phenanthridine (phent) derivates as cyclometalating ligands and picolinate as an ancillary ligand are described. The influence of extended conjugation, rigidity, and hydrophobicity as well as the electronic nature of the substituents were investigated in relation to the photoluminescence, PL, and electrochemiluminescence, ECL, properties. A significant increase of ECL in aqueous media is observed upon extension of the aromatic system or by substituting the phenyl with a dibenzofurane moiety, in compounds 2 and 3 , respectively. Under real immunoassay conditions, these complexes achieve up to 4-fold higher ECL efficiency than the commercial ruthenium standard. These values, among the highest reported in the literature under these conditions, confirm the potential of iridium complexes as alternative labels in commercial instruments.

Introduction: The authors analyzed a series of ankylosing spondylitis patients with cervical spine fracture undergoing posterior stabilization using spinal navigation based on intraoperative CT imaging. The purpose of this study was to evaluate the accuracy and safety of navigated posterior stabilization and to analyze the adequacy of this method for treatment of fractures in ankylosed cervical spine., Methods: Prospectively collected clinical data, together with radiological documentation of a series of 8 consecutive patients with 9 cervical spine fracture were included in the analysis. The evaluation of screw insertion accuracy based on postoperative CT imaging, description of instrumentation-related complications and evaluation of morphological and clinical results were the subjects of interest., Results: Of the 66 implants inserted in all cervical levels and in upper thoracic spine, only 3 screws (4.5%) did not meet the criteria of anatomically correct insertion. Neither screw malposition nor any other intraoperative events were complicated by any neural, vascular or visceral injury. Thus we did not find a reason to change implant position intraoperatively or during the postoperative period. The quality of intraoperative CT imaging in our group of patients was sufficient for reliable trajectory planning and implant insertion in all segments, irrespective of the habitus, positioning method and comorbidities. In addition to stabilization of the fracture, the posterior approach also allows reducing preoperative kyphotic position of the cervical spine. In all patients, we achieved a stable situation with complete bone fusion of the anterior part of the spinal column and lateral masses at one year follow-up., Conclusion: Spinal navigation based on intraoperative CT imaging has proven to be a reliable and safe method of stabilizing cervical spine with ankylosing spondylitis. The strategy of posterior stabilization seems to be a suitable method providing high primary stability and the conditions for a subsequent high fusion rate.

The dissociation of hierarchically formed dimeric triple lithium bridged triscatecholate titanium(IV) helicates with hydrocarbyl esters as side groups is systematically investigated in DMSO. Primary alkyl, alkenyl, alkynyl as well as benzyl esters are studied in order to minimize steric effects close to the helicate core. The 1 H NMR dimerization constants for the monomer-dimer equilibrium show some solvent dependent influence of the side chains on the dimer stability. In the dimer, the ability of the hydrocarbyl ester groups to aggregate minimizes their contacts with the solvent molecules. Due to this, most solvophobic alkyl groups show the highest dimerization tendency followed by alkenyls, alkynyls and finally benzyls. Furthermore, trends within the different groups of compounds can be observed. For example, the dimer is destabilized by internal double or triple bonds due to π-π repulsion. A strong indication for solvent supported London dispersion interaction between the ester side groups is found by observation of an even/odd alternation of dimerization constants within the series of n-alkyls, n-Ω-alkenyls or n-Ω-alkynyls. This corresponds to the interaction of the parent hydrocarbons, as documented by an even/odd melting point alternation., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

This corrects the article DOI: 10.1038/sdata.2017.3.

Novel analogues of oxadiazole-substituted naphtho[2,3-b]thiophene-4,9-diones were synthesized in which the tricyclic quinone skeleton was systematically replaced with simpler moieties, such as structures with fewer rings and open-chain forms, while the oxadiazole ring was maintained. In addition, variants of the original 1,2,4-oxadiazole ring were explored. Overall, the complete three-ring quinone was essential for potent suppression of human keratinocyte hyperproliferation, whereas analogous anthraquinones were inactive. Also, the oxadiazole ring per se was not sufficient to elicit activity. However, rearrangement of the heteroatom positions in the oxadiazole ring resulted in highly potent inhibitors with compound 24b being the most potent analogue of this series showing an IC 50 in the nanomolar range. Furthermore, experiments in isolated enzymatic assays as well as in the keratinocyte-based hyperproliferation assay did not support a major role of redox cycling in the mode of action of the compounds., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment.

Diastereoselective radical coupling was achieved with chiral auxiliaries. The radicals were generated by anodic decarboxylation of five malonic acid derivatives. These were prepared from benzyl malonates and four menthol auxiliaries. Coelectrolyses with 3,3-dimethylbutanoic acid in methanol at platinum electrodes in an undivided cell afforded hetero-coupling products in 22-69% yield with a diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21-50% yield with ratios of diastereomers being 1.17:2.00:0.81 to 7.03:2.00. The stereochemistry of the new stereogenic centers was confirmed by X-ray structure analysis and 13 C NMR data.

Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO 2 + fragment is among the most important measurements for such analyses. Here, we show that a non-OA CO 2 + signal can arise from reactions on the particle vaporizer, ion chamber, or both, induced by thermal decomposition products of inorganic salts. In our tests (eight instruments, n = 29), ammonium nitrate (NH 4 NO 3 ) causes a median CO 2 + interference signal of +3.4% relative to nitrate. This interference is highly variable between instruments and with measurement history (percentiles P 10-90 = +0.4 to +10.2%). Other semi-refractory nitrate salts showed 2-10 times enhanced interference compared to that of NH 4 NO 3 , while the ammonium sulfate ((NH 4 ) 2 SO 4 ) induced interference was 3-10 times lower. Propagation of the CO 2 + interference to other ions during standard AMS and ACSM data analysis affects the calculated OA mass, mass spectra, molecular oxygen-to-carbon ratio (O/C), and f 44 . The resulting bias may be trivial for most ambient data sets but can be significant for aerosol with higher inorganic fractions (>50%), e.g., for low ambient temperatures, or laboratory experiments. The large variation between instruments makes it imperative to regularly quantify this effect on individual AMS and ACSM systems.

Neutral green-emitting four-coordinate Cu(I) complexes with general formula POPCu(NN), where POP = bis[2-(diphenylphosphino)phenyl]ether and NN = substituted 2-pyridine-1,2,4-triazole ligands, were synthesized. The crystal structures of (POPCuMeCN)(+)(PF6)(-) (1), POPCuPhPtp (2a, PhPtp = 2-(5-phenyl-2H-[1,2,4]triazol-3-yl)-pyridine), and POPCu(3,5-2FPhPtp) (2d, 3,5-2FPhPtp = 2-(5-(3,5-difluorophenyl)-2H-1,2,4-triazol-3-yl)pyridine) were determined by single-crystal X-ray diffraction analysis. The electronic and photophysical properties of the complexes were examined by UV-vis, steady-state, and time-resolved spectroscopy. At room temperature, weak emission was observed in solution, while in the solid state, all complexes exhibit intense green emission with quantum yield up to 0.54. The electronic and photophysical properties were further supported by calculation performed at the (time-dependent) density functional theory level. One of the complexes was also tested as dopant in electroluminescent devices.

The title compounds, C22H29NO2 (3) and C22H29NO2 (4) [systematic names: (1S*,2R*)-7-meth-oxy-2-methyl-3-(4-phenyl-but-yl)-2,3,4,5-tetra-hydro-1H-3-benzazepin-1-ol and (1R*,2R*)-7-meth-oxy-2-methyl-3-(4-phenyl-but-yl)-2,3,4,5-tetra-hydro-1H-3-benzazepin-1-ol, are diastereomers with the relative configuration of the adjacent hydroxyl and methyl groups at the seven-membered azepine ring being trans in (3) and cis in (4). In the crystals the orientation of these groups is -anti-periplanar (3) and +syn-clinal (4). In both cases, the crystals studied proved to be of a racemic mixture, with relative configurations (R*,S*)-3 and (R*,R*)-4. In both compounds, the seven-membered azepine ring has a chair-like conformation, and the 4-phenyl-butyl side chain adopts a extended conformation in (R*,S*)-3, but a twisted conformation in (R*,R*)-4. In the crystal of (S*,R*)-3, mol-ecules are linked via C-H⋯O hydrogen bonds, forming slabs parallel to the ac plane. In the crystal of (R*,R*)-4, mol-ecules are linked via O-H⋯N hydrogen bonds, forming chains propagating along the c-axis direction. The chains are linked by C-H⋯O hydrogen bonds, forming slabs parallel to the ac plane.

In the title compound, C25H27NO4S, which crystallized as a racemate, the relative configuration of the adjacent OH and CH3 groups on the azepine ring is trans. The seven-membered azepin ring has a chair-like conformation. The planar aromatic rings of the benzyl and tosyl-ate moiety are inclined to the planar 3-benzazepine ring by 78.39 (15) and 77.03 (14)°, respectively, and to each another by 13.82 (15)°. In the crystal, mol-ecules are linked via O-H⋯O and C-H⋯O hydrogen bonds, forming double-stranded chains along the a-axis direction. The chains are linked via C-H⋯π inter-actions, forming a three-dimensional architecture.

The preparation of a series of planar chiral, ferrocenyl-substituted hydrosilanes as precursors of ferrocene-stabilized silicon cations is described. These molecules also feature stereogenicity at the silicon atom. The generation and (29)Si NMR spectroscopic characterization of the corresponding silicon cations is reported, and problems arising from interactions of the electron-deficient silicon atom and adjacent C(sp(3))-H bonds or aromatic π donors are discussed. These issues are overcome by tethering another substituent at the silicon atom to the ferrocene backbone. The resulting annulation also imparts conformational rigidity and steric hindrance in such a way that the central chirality at the silicon atom is set with complete diastereocontrol. These chiral Lewis acid catalysts were then tested in difficult Diels-Alder reactions, but no enantioinduction was seen., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

1,3,5-Triazapentadienes usually show U- or twisted S-shaped conformations along the N-C-N-C-N skeleton due to dominating n/π* interactions. If, however, the 1,3,5-triazapentadiene unit is part of a ring, its W conformation might be restricted to the plane. Here, we describe the synthesis of 13 new 1,3,5-triazapentadienes 10-12, which are sterically restrained by incorporation into six- or seven-membered ring systems, by addition of a lithiated primary amine or hydrazine 5 to a dinitrile 7, 8, or 9 with the two cyano groups in 1,3 or 1,4 distance. These novel compounds show very strong tendency for aggregation due to hydrogen bonding, especially to form homodimers as seen from X-ray data in the solid state. Additional hydrogen bonding generates also linear chains in the crystal. Several of the new compounds show fluorescence in solution. Quantum chemical DFT calculations were used for evaluation of the dimerization energies and for interpretation of the photophysical properties.

The reaction of the neutral diphosphanide [((Cl)Im(Dipp))P-P(Cl)(Dipp)] (6) ((Cl)Im(Dipp) = 4,5-dichloro-1,3-bis(Dipp)-imidazol-2-yl; Dipp = 2,6-di-iso-propylphenyl) with methyl triflate (MeOTf) leads to the formation of cationic diphosphane [((Cl)Im(Dipp))(Me)P-P(Cl)(Dipp)](+) (8+) in a stereoselective methylation. In contrast, reacting with the Lewis acid GaCl3 yields cationic diphosphene [((Cl)Im(Dipp))P=P(Dipp)](+) (7+), which is explained by a low P-Cl bond dissociation energy. The significantly polarized P=P double bond in 7+ allows for its utilization as an acceptor for nucleophiles - the reaction with Cl(-) regenerates diphosphanide and the reaction with PMe3 gives cation [((Cl)Im(Dipp))P-P(PMe3)(Dipp)] (9+). In depth DFT investigation provides detailed insights into the bonding situation of the reported compounds.

All diastereoisomeric decahydroquinoxalines representing conformationally restricted analogs of κ agonists U-50,488 and GR-89,696 have been prepared. Cis/trans configured compound 7 is by far the highest binding diastereoisomer with a Ki of 0.35 nM. Racemates 4, 6, and 7 were separated into enantiomers. (+)-(4aR,5S,8aS)-Configured enantiomer 7b was identified as a high affinity (Ki=0.25 nM) κ ligand with high selectivity over μ and δ receptors. It acts as full agonist with an EC50 value of 2.0 nM in the [(35)S]GTPγS assay, while enantiomer 7a showed an EC50 value of 1000 nM., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Conformationally constrained perhydroquinoxalines 4 show high κ receptor affinity, selectivity over related receptors and full agonistic activity. Since the κ affinity can be correlated with the dihedral angle of the ethylenediamine pharmacophore (4a: 55°/71°), the dihedral angles of the postulated cyclopentane derivative 5a (73°/84°) and indane derivative 6a (77°/81°) were calculated. The first step of the synthesis represents a double Henry reaction of 1,4-dialdehydes 8 and 10 with nitromethane, leading predominantly to the trans,trans-configured nitrodiols 9 and 11. X-ray crystal structure analyses of 9 and 11 led to dihedral angles O2 N−C−C−OH of 73.4 and 88.3°, respectively, which reflect the calculated dihedral angles of the hypothesized final products 5a and 6a., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The enantiomerically and diastereomerically pure tricyclic oxazolidine cis-10 was prepared in a five step synthesis starting with 1-bromo-2-iodobenzene. Me3SiCN and allylSiMe3 reacted with cis-10 in the presence of TiCl4 to form the nitrile (3S)-11 and the allyl derivative (3S)-12 with high diastereoselectivity. The hydrogenolytic removal of the chiral auxiliary failed, since the endocyclic benzyl-N-bond was cleaved simultaneously. Therefore the N-(hydroxyethyl)amide of (3S)-12 was transformed into the enamide 27, which was hydrolyzed to afford the secondary amide 28. The enamide strategy to remove the chiral auxiliary from (3S)-11 led to complete racemization due to fast deprotonation in α-position of the cyano moiety. Two pairs of enantiomers 30a-b/ent-30a-b with prototypical σ substituents at the N-atom were prepared. The low σ1 affinity of the tetrahydro-2-benzazepines (ent-30b, Ki = 407 nM) is attributed to the short distance between the two lipophilic aromatic moieties.

The series of differently substituted ketenimines 1 was hydroluminated using di-iso-butyl aluminum hydride. For the sterically congested ketenimine 1a, preferred hydroalumination of the C═N-bond was proven by X-ray crystallography (compound 5a). In situ treatment of the hydroaluminated ketenimines 5 with various heterocumulenes like carbodiimides, isocycanates, isothiocyanates and ketenimines as electrophiles and subsequent hydrolytic workup resulted in novel enamine derived amide species in case of N-attack (sterically less hindered ketenimines) under formation of a new C-N-bond or in 1,3-diimines by C-C-bond-formation in case of bulky substituents at the ketenimine-nitrogen atom. Furthermore, domino reactions with more than 1 equiv of the electrophile or by subsequent addition of two different electrophiles are possible and lead to polyfunctional amide derivatives of the biuret type which are otherwise not easily accessible.

A series of novel benzene centered mono-, bis- and tris-1,3,5-triazapentadiene ligands was synthesized and investigated with respect to their reactivity towards triphenylborane. The resulting blue-fluorescent boron complexes with a six-membered ring chelate structure show excellent thermal and chemical stability. All title compounds were completely characterized including X-ray diffraction studies for and . Whereas the absorption spectra of all three classes of compounds are similar, the fluorescence spectra show distinct differences. Thus, the emission spectra of show Stokes shifts of 4100-6700 cm(-1) with low quantum yields both in solution and in the solid state. However, the more bulky compounds show markedly larger molar extinction coefficients and smaller bathochromic shifts compared to . For all compounds, we observe significantly more intense red-shifted fluorescence in the solid state compared to that in dichloromethane solutions. For the interpretation of the absorption properties TD-DFT studies were performed based on DFT geometry optimizations.

We have synthesized a series of luminescent trigonal [CuX(dtbphen)] (X = I (), Br (), Cl (), CN (), dtbphen = 2,9-di-tert-butylphenanthroline) and tetrahedral [Cu2(μ-I)2(L)2] (L = phenanthroline (), 2,9-dimethylphenanthroline ()) copper diimine complexes. Bearing in mind the chemical simplicity of this class of long-known Cu(i) phenanthroline compounds, it is surprising that they exhibit non-trivial photophysical properties, which have not been fully recognized. They display broad XMLCT absorption between ca. 450-600 nm, and the broad emission between ca. 550-850 nm in the solid state occurring with lifetimes on the μs timescale indicates phosphorescence, although the energetic overlap between excitation and emission suggests thermally activated delayed fluorescence (TADF) from S1. In line with the latter assumption, low temperature measurements of in the solid state show an energetic separation of emission and excitation. However, a counter-intuitive decrease of emission intensity and simultaneous increase of the emission lifetime at low temperatures are observed for , which indicates two triplet states also being involved. Our DFT and TD-DFT calculations show that emission from the lowest excited triplet state T1 is of (3)LMXCT nature, separated by only ca. 0.16 eV from S1. Low temperature photophysical measurements at 77 K in a glassy matrix of in 2-Me-THF and of in the solid state are in agreement with the theoretical results, revealing in addition that π-interactions in the solid state also greatly influence the photophysical properties, making a clear conclusion towards TADF ambiguous. This study suggests that other related simple and long-known Cu(i) systems may exhibit a similar, more complex excited state behavior than previously appreciated, involving several emitting states and important intermolecular interactions.

The terpenols l(-)-borneol, (1S2S3S5R)-3-pinanol, (-)-menthol, and (-)-myrtenol are easily available chiral alcohols for the preparation of enantiomerically pure catechol esters -H2. Those ligands are used for the hierarchical assembly of triple lithium-bridged dinuclear titanium(iv) triscatecholate helicates Li[Li3()6Ti2]. In solution, the dimeric species are in a solvent dependent equilibrium with the monomer Li2[()3Ti]. The equilibrium is studied by (1)H NMR. CD spectroscopy indicates that the configuration at the complex units of the enantiomerically pure dimeric α-chiral derivatives Li[Li3()6Ti2] is opposite to the configuration of the monomers Li2[()3Ti]. For the γ-chiral complex Li2[()3Ti] only a de of 25% is observed and in this case no interpretation of the mechanism of stereocontrol is possible.

In this study the scope of the 1,1-carboboration reaction was extended to the preparation of mixed heterole-based conjugated π-systems. Two arylbis(alkynyl)phosphane starting materials 2 were synthesized bearing two thiophene isomers at the alkyne units and the bulky tipp-substituent (tipp=2,4,6-triisopropylphenyl) at the phosphorous atom. The bis(thienylethynyl)phosphanes 2 were converted into the corresponding 2,5-thienyl-substituted 3-borylphospholes 4 in a double 1,1-carboboration reaction sequence employing the strongly electrophilic B(C6 F5 )3 reagent under mild reaction conditions. Subsequent Suzuki-Miyaura type cross-coupling yielded the corresponding 3-phenylphospholes 7 in a one-pot procedure from phosphanes 2 in high yields. Phospholes 7 were converted into the respective phosphole oxides 8. A photophysical characterization of derivatives 7 and 8 was carried out. The results presented here demonstrate the suitability of the 1,1-carboboration reaction for the preparation of phosphole-/thiophene-based, light-emitting systems., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A large set of tetrahydro-2-benzazepines with an α-hydroxy or α-(aryl)alkoxy substituted benzyl moiety in the 5-position was prepared according to the recently reported C6C1 + C3N synthetic strategy. The Heck reaction of 2-iodobenzaldehyde acetal 4 and the subsequent Stetter reaction led to the ketone 7, which was reduced diastereoselectively to form the like-configured alcohol 8. The diastereomeric unlike-configured alcohol 9 was obtained by a Mitsunobu inversion of 8. Alkylation and reductive cyclization of the diastereomeric alcohols 8 and 9 provided like- and unlike-configured 2-benzazepines 13 and 23, which allowed the introduction of various substituents at the N-atom. Analysis of the relationship between the structure and the σ1 affinity revealed that large substituents such as the butyl, benzyl or 4-phenylbutyl moiety at the benzazepine N-atom resulted in high affinity ligands. A p-methoxybenzyl ether is less tolerated by the σ1 receptor than a methyl ether or an alcohol. The unlike-configured alcohols 25d and 27d show slightly higher σ1 affinity than their like-configured diastereomers 15d and 17d. With respect to the σ1 affinity, σ1/σ2 selectivity and lipophilic ligand efficiency, like- and unlike-configured alcohols 15d and 25d represent the most promising σ1 ligands of this series. Interactions of the novel 2-benzazepines with various binding sites of the NMDA receptor were not observed.

A study on the key parameters involved in the anion-binding process and catalytic activity of the new family of CH-bond-based, anion-binding bis-triazole catalysts BisTri was carried out. The effects of substitution at the side arms and the central backbone structure of the catalyst were investigated. Electron-deficient 3,5-bis(trifluoromethyl)phenyl groups at the side arms led to the most strongly bound structures. The evaluation of differently shaped anions showed remarkable binding selectivity of the BisTri derivatives for the chloride anion. Examination of various nucleophiles in a model catalytic alkylation reaction suggested a more complex mechanism than the expected SN 1, in which the nucleophiles also participate partially in activation of the electrophile. DFT calculations were performed to investigate the relationship between the catalyst conformation and the binding affinity. Finally, in silico design and identification of a new, more efficient BisTri catalyst was accomplished., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

4,5-Dimethyl-1,2-bis(1-naphthylethynyl)benzene (12) undergoes a rapid multiple ring-closure reaction upon treatment with the strong boron Lewis acid B(C6F5)3 to yield the multiply annulated, planar conjugated π-system 13 (50 % yield). In the course of this reaction, a C6F5 group was transferred from boron to carbon. Treatment of 12 with CH3B(C6F5)2 proceeded similarly, giving a mixture of 13 (C6F5-transfer) and the product 15, which was formed by CH3-group transfer. 1,2-Bis(phenylethynyl)benzene (8 a) reacts similarly with CH3B(C6F5)2 to yield a mixture of the respective C6F5- and CH3-substituted dibenzopentalenes 10 a and 16. The reaction is thought to proceed through zwitterionic intermediates that exhibit vinyl cation reactivities. Some B(C6F5)3-substituted species (26, 27) consequently formed by in situ deprotonation upon treatment of the respective 1,2-bis(alkynyl)benzene starting materials (24, 8) with the frustrated Lewis pair B(C6F5)3/P(o-tolyl)3. The overall formation of the C6F5-substituted products formally require HB(C6F5)2 cleavage in an intermediate dehydroboration step. This was confirmed in the reaction of a thienylethynyl-containing starting material 21 with B(C6F5)3, which gave the respective annulated pentalene product 23 that had the HB(C6F5)2 moiety 1,4-added to its thiophene ring. Compounds 12-14, 23, and 26 were characterized by X-ray diffraction., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)