Iridium Corroles Exhibit Weak Near-Infrared Phosphorescence but Efficiently Sensitize Singlet Oxygen Formation.

Six-coordinate iridium(III) triarylcorrole derivatives, Ir[TpXPC)]L2, where TpXPC = tris(para-X-phenyl)corrole (X = CF3, H, Me, and OCH3) and L = pyridine (py), trimethylamine (tma), isoquinoline (isoq), 4-dimethylaminopyridine (dmap), and 4-picolinic acid (4pa), have been examined, with a view to identifying axial ligands most conducive to near-infrared phosphorescence. Disappointingly, the phosphorescence quantum yield invariably turned out to be very low, about 0.02 - 0.04% at ambient temperature, with about a two-fold increase at 77 K. Phosphorescence decay times were found to be around ~5 µs at 295 K and ~10 µs at 77 K. Fortunately, two of the Ir[TpCF3PC)]L2 derivatives, which were tested for their ability to sensitize singlet oxygen formation, were found to do so efficiently with quantum yields Φ(1O2) = 0.71 and 0.38 for L = py and 4pa, respectively. Iridium corroles thus may hold promise as photosensitizers in photodynamic therapy (PDT). The possibility of varying the axial ligand and of attaching biotargeting groups at the axial positions makes iridium corroles particularly exciting as PDT drug candidates

Stable optical oxygen sensing materials based on click-coupling of fluorinated platinum(II) and palladium(II) porphyrins—A convenient way to eliminate dye migration and leaching

AbstractNucleophilic substitution of the labile para-fluorine atoms of 2,3,4,5,6-pentafluorophenyl groups enables a click-based covalent linkage of an oxygen indicator (platinum(II) or palladium(II) 5,10,15,20-meso-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin) to the sensor matrix. Copolymers of styrene and pentafluorostyrene are chosen as polymeric materials. Depending on the reaction conditions either soluble sensor materials or cross-linked microparticles are obtained. Additionally, we prepared Ormosil-based sensors with linked indicator, which showed very high sensitivity toward oxygen. The effect of covalent coupling on sensor characteristics, stability and photophysical properties is studied. It is demonstrated that leaching and migration of the dye are eliminated in the new materials but excellent photophysical properties of the indicators are preserved

Establishing low-energy sequential decomposition pathways of leucine enkephalin and its N- and C-terminus fragments using multiple-resonance CID in quadrupolar ion guide

The simultaneous resonant low-energy excitation of leucine enkephalin and its fragment ions was demonstrated in a collision cell of the multipole-quadrupole time-of-flight instrument. Using low-amplitude multiple-resonance excitation CID, we were able to show the exclusive sequential fragmentation of N- and C-terminus fragments all the way to the final fragments—immonium ions of phenylalanine or tyrosine. In this CID mode the single-channel dissociation of each new generation of fragments followed the lowest energy decomposition pathways observable on the time scale of our experiment. Up to six generations of sequential dissociation were carried out in multiple-resonance CID experiments. The direct qualitative comparison of fragmentation of axial-acceleration versus resonant (radial) CID was performed in the same instrument. In both activation methods, fragmentation patterns suggested complex decomposition mechanisms attributable to dynamic competition between sequential and parallel dissociation channels

New highly fluorescent pH indicator for ratiometric RGB imaging of pCO2

A new diketo-pyrrolo-pyrrole (DPP) indicator dye for optical sensing of carbon dioxide is prepared via a simple one step synthesis from commercially available low cost 'Pigment Orange 73'. The pigment is modified via alkylation of one of the lactam nitrogens with a tert-butylbenzyl group. The indicator dye is highly soluble in organic solvents and in polymers and shows pH-dependent absorption (λmax 501 and 572 nm for the protonated and deprotonated forms, respectively) and emission spectra (λmax 524 and 605 nm for the protonated and deprotonated forms, respectively). Both the protonated and the deprotonated forms show high fluorescence quantum yields (Φprot 0.86; Φdeprot 0.66). Hence, colorimetric read-out and ratiometric fluorescence intensity measurements are possible. The emission of the two forms of the indicator excellently matches the response of the green and the red channels of an RGB camera. This enables imaging of carbon dioxide distribution with a simple and low cost optical set-up. The sensor based on the new DPP dye shows very high sensitivity and is particularly promising for monitoring atmospheric levels of carbon dioxide

Sampling in low oxygen aquatic environments: The deviation from anoxic conditions

Studies of the impact of hypoxic or anoxic environments on both climate and ecosystems rely on a detailed characterization of the oxygen (O-2) distribution along the water column. The former trivial separation between oxic and anoxic conditions is now often redefined as a blurry concentration range in which both aerobic and anaerobic processes might coexist, both in situ and during experimental incubations. The O-2 concentrations during such incubations have often been assumed to be equal to in situ levels, but the concentration was rarely measured. In order to evaluate the actual oxygen concentration in samples collected from low-oxygen environments, a series of measurements were performed on samples collected in the Pacific oxygen minimum zones. Our results show a significant deviation from in situ anoxic conditions in samples collected by Niskin bottles where leakage from the bottle material resulted in O-2 concentrations of up to 1 mu M. Subsequent sampling further increased the O-2 contamination. Sampling and analysis by Winkler method resulted in variable apparent concentrations of 2-4 mu M. Two common procedures to avoid atmospheric contamination were also tested: allowing gentle overflow and keeping the sampling bottle submersed in a portion of the sampled water. Both procedures resulted in similar O-2 contamination with values of 0.5-1.5 mu M when bottles were immediately closed and measurements performed with optical sensors, and 3-4 mu M apparent concentration when analyzed by the Winkler method. Winkler titration is thus not suited for analysis of low-O-2 samples. It can be concluded that incubation under anoxic conditions requires deoxygenation after conventional sampling.We would like to thank Lars B. Pedersen at Aarhus University for the construction of STOX sensors. We are grateful to the cruise leaders Bess B. Ward and Frank Stewart for the invitation to participate in OMZ cruises. We also thank the captains and crews of the R/Vs L'Atalante, New Horizon, Oceanus and Sally Ride. We additionally thank A. Franco-Garcia, M. Giraud, J. Ledesma, F. Baurand, D. Lefevre, B. Dewitte, C. Maes, V. Garcon and the PACOP platform (Toulouse) for operational and experimental support during the AMOP cruise. This work was funded by the Poul Due Jensen Foundation and co-financed by the 2014-2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia (to EGR, project reference FEDER-UCA18-107225)

NIR optical carbon dioxide sensors based on highly photostable dihydroxy-aza-BODIPY dyes

A new class of pH-sensitive indicator dyes for optical carbon dioxide sensors based on di-OH-aza-BODIPYs is presented. These colorimetric indicators show absorption maxima in the near infrared range (λmax 670–700 nm for the neutral form, λmax 725–760 nm for the mono-anionic form, λmax 785–830 nm for the di-anionic form), high molar absorption coefficients of up to 77 000 M−1 cm−1 and unmatched photostability. Depending on the electron-withdrawing or electron-donating effect of the substituents the pKa values are tunable (8.7–10.7). Therefore, optical carbon dioxide sensors based on the presented dyes cover diverse dynamic ranges (0.007–2 kPa; 0.18–20 kPa and 0.2–100 kPa), which enables different applications varying from marine science and environmental monitoring to food packaging. The sensors are outstandingly photostable in the absence and presence of carbon dioxide and can be read out via absorption or via the luminescence-based ratiometric scheme using the absorption-modulated inner-filter effect. Monitoring of the carbon dioxide production/consumption of a Hebe plant is demonstrated

Measurement of oxygen transfer from air into organic solvents:Oxygen transfer from air into organic solvents

BACKGROUND: The use of non‐aqueous organic media is becoming increasingly important in many biotechnological applications in order to achieve process intensification. Such media can be used, for example, to directly extract poorly water‐soluble toxic products from fermentations. Likewise many biological reactions require the supply of oxygen, most normally from air. However, reliable online measurements of oxygen concentration in organic solvents (and hence oxygen transfer rates from air to the solvent) has to date proven impossible due to limitations in the current analytical methods. RESULTS: For the first time, online oxygen measurements in non‐aqueous media using a novel optical sensor are demonstrated. The sensor was used to measure oxygen concentration in various organic solvents including toluene, THF, isooctane, DMF, heptane and hexane (which have all been shown suitable for several biological applications). Subsequently, the oxygen transfer rates from air into these organic solvents were measured. CONCLUSION: The measurement of oxygen transfer rates from air into organic solvents using the dynamic method was established using the solvent resistant optical sensor. The feasibility of online oxygen measurements in organic solvents has also been demonstrated, paving the way for new opportunities in process control. © 2015 The Authors. Journal of Chemical Technology & Biotechnology published by JohnWiley & Sons Ltd on behalf of Society of Chemical Industry

Features of feeding for pacific herring <i>Clupea pallasii,</i> walleye pollock <i>Theragra chalcogramma</i>, and arabesque greenling <i>Pleurogrammus azonus</i> in Peter the Great Bay (Japan Sea) in summer season

Qualitative and quantitative indices of feeding and competitive relationships are investigated for pacific herring Clupea pallasii , walleye pollock Theragra chalcogramma , and arabesque greenling Pleurogrammus azonus on the data of bottom trawl surveys conducted over the shelf and upper continental slope of Peter the Great Bay in June-September of 2002-2009. Daily rations of these species in summer are estimated as 4.5, 3.0 and 4.3 % of body weight on average, respectively. The diet depends on their bathymetric distribution and structure of prey: generally, the portion of plankton and nektobenthos reflects the species ability to dwell beyond the bottom and changes from 66.9 and 32.1 % for herring and 45.2 and 46.9 % for pollock to 30.2 and 31.8 % for greenling. The rest of the greenling diet is presented by benthic invertebrates (24.8 %) and nekton (13.2 %). Mysids are the main common diet component for all three species, their portion in the herring and pollock diets is extremely high in Peter the Great Bay comparing with other habitats of these species, obviously because of high abundance of mysid shrimps and low concentrations of large-sized zooplankton (particularly euphausiids) in the Bay. Role of the considered species in demersal ichthyocenosis of Peter the Great Bay is not high enough for food competition between them, taking into account their active seasonal migrations and low stocks of herring and pollock in recent times