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1.
New Phytol ; 2020 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-32386326

RESUMO

Lycophytes are the earliest diverging extant lineage of vascular plants, sister to all other vascular plants. Given that most species are adapted to ever-wet environments, it has been hypothesized that lycophytes, and by extension the common ancestor of all vascular plants, have few adaptations to drought. We investigated the responses to drought of key fitness-related traits such as stomatal regulation, shoot hydraulic conductance (Kshoot ) and stem xylem embolism resistance in Selaginella haematodes and S. pulcherrima, both native to tropical understory. During drought stomata in both species were found to close before declines in Kshoot , with a 50% loss of Kshoot occurring at -1.7 and -2.5 MPa in S. haematodes and S. pulcherrima, respectively. Direct observational methods revealed that the xylem of both species was resistant to embolism formation, with 50% of embolized xylem area occurring at -3.0 and -4.6 MPa in S. haematodes and S. pulcherrima, respectively. X-ray microcomputed tomography images of stems revealed that the decline in Kshoot occurred with the formation of an air-filled lacuna, disconnecting the central vascular cylinder from the cortex. We propose that embolism-resistant xylem and large capacitance, provided by collapsing inner cortical cells, is essential for Selaginella survival during water deficit.

2.
New Phytol ; 2020 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-32455476

RESUMO

Photosynthetic 'least-cost' theory posits that the optimal trait combination for a given environment is that where the summed costs of photosynthetic water and nutrient acquisition/use are minimised. The effects of soil water and nutrient availability on photosynthesis should be stronger as climate-related costs for both resources increase. Two independent datasets of photosynthetic traits, Globamax (1509 species, 288 sites) and Glob13C (3645 species, 594 sites), were used to quantify biophysical and biochemical limitations of photosynthesis and the key variable Ci /Ca (CO2 drawdown during photosynthesis). Climate and soil variables were associated with both datasets. The biochemical photosynthetic capacity was higher on alkaline soils. This effect was strongest at more arid sites, where water unit-costs are presumably higher. Higher values of soil silt and depth increased Ci /Ca , likely by providing greater H2 O supply, alleviating biophysical photosynthetic limitation when soil water is scarce. Climate is important in controlling the optimal balance of H2 O and N costs for photosynthesis, but soil properties change these costs, both directly and indirectly. In total, soil properties modify the climate-demand driven predictions of Ci /Ca by up to 30% at a global scale.

3.
J Exp Bot ; 71(14): 4333-4344, 2020 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-32279077

RESUMO

Adapting agriculture to climate change is driving the need for the selection and breeding of drought-tolerant crops. The aim of this study was to identify key drought tolerance traits and determine the sequence of their water potential thresholds across three grapevine cultivars with contrasting water use behaviors, Grenache, Syrah, and Semillon. We quantified differences in water use between cultivars and combined this with the determination of other leaf-level traits (e.g. leaf turgor loss point, π TLP), leaf vulnerability to embolism (P50), and the hydraulic safety margin (HSM P50). Semillon exhibited the highest maximum transpiration (Emax), and lowest sensitivity of canopy stomatal conductance (Gc) to vapor pressure deficit (VPD), followed by Syrah and Grenache. Increasing Emax was correlated with more negative water potential at which stomata close (Pgs90), π TLP, and P50, suggesting that increasing water use is associated with hydraulic traits allowing gas exchange under more negative water potentials. Nevertheless, all the cultivars closed their stomata prior to leaf embolism formation. Modeling simulations demonstrated that despite a narrower HSM, Grenache takes longer to reach thresholds of hydraulic failure due to its conservative water use. This study demonstrates that the relationships between leaf hydraulic traits are complex and interactive, stressing the importance of integrating multiple traits in characterizing drought tolerance.

4.
Plant Cell Environ ; 43(4): 854-865, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31953855

RESUMO

Identifying the drivers of stomatal closure and leaf damage during stress in grasses is a critical prerequisite for understanding crop resilience. Here, we investigated whether changes in stomatal conductance (gs ) during dehydration were associated with changes in leaf hydraulic conductance (Kleaf ), xylem cavitation, xylem collapse, and leaf cell turgor in wheat (Triticum aestivum). During soil dehydration, the decline of gs was concomitant with declining Kleaf under mild water stress. This early decline of leaf hydraulic conductance was not driven by cavitation, as the first cavitation events in leaf and stem were detected well after Kleaf had declined. Xylem vessel deformation could only account for <5% of the observed decline in leaf hydraulic conductance during dehydration. Thus, we concluded that changes in the hydraulic conductance of tissues outside the xylem were responsible for the majority of Kleaf decline during leaf dehydration in wheat. However, the contribution of leaf resistance to whole plant resistance was less than other tissues (<35% of whole plant resistance), and this proportion remained constant as plants dehydrated, indicating that Kleaf decline during water stress was not a major driver of stomatal closure.

5.
Inorg Chem ; 59(2): 1496-1512, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31913029

RESUMO

We report a detailed characterization of Eu3+ and Tb3+ complexes derived from a tripyridinophane macrocycle bearing three acetate side arms (H3tpptac). Tpptac3- displays an overall basicity (∑ log KiH) of 24.5, provides the formation of mononuclear ML species, and shows a good binding affinity for Ln3+ (log KLnL = 17.5-18.7). These complexes are also thermodynamically stable at physiological pH (pEu = 18.6, pTb = 18.0). It should be noted that the pGd value of Gd-tpptac (18.4) is only slightly lower than that of commercially available MRI contrast agents such as Gd-dota (pGd = 19.2). Moreover, a very good selectivity for these ions over the endogenous cations (log KCuL = 14.4, log KZnL = 12.9, and log KCaL = 9.3) is observed. The X-ray structure of the terbium complex shows the metal coordinated by the nine N6O3 donor set of the ligand and one inner-sphere water molecule. DFT calculations result in two Eu-tpptac structures with similar bond energies (ΔE = 0.145 eV): one structure in which the water is coordinated to the metal ion and one structure in which the water molecule is farther away from the ion, bound to the ligand with an OH-π bond. By detailed luminescence experiments, we demonstrate that the europium complex in aqueous solution presents a hydration equilibrium between nine-coordinate, dehydrated [Eu-tpptac]0 and ten-coordinate, monohydrated [Eu-tpptac(H2O)]0 species. A similar trend is observed for the terbium complex. Despite the presence of this hydration equilibrium, the H3tpptac ligand sensitizes Eu3+ and Tb3+ luminescence efficiently in buffered water at physiological pH. Particularly, the terbium complex displays a long excited-state lifetime of 2.24 ms and an overall quantum yield of 33% with a brightness of 3600 M-1 cm-1. Such features of Ln3+ complexes of H3tpptac indicate that this platform appears to be particularly appealing for the further development of luminescent lanthanide labels.

6.
Ann Bot ; 124(7): 1173-1184, 2020 01 06.
Artigo em Inglês | MEDLINE | ID: mdl-31227829

RESUMO

BACKGROUND AND AIMS: Hydraulic studies are currently biased towards conifers and dicotyledonous angiosperms; responses of arborescent monocots to increasing temperature and drought remain poorly known. This study aims to assess xylem resistance to drought-induced embolism in palms. METHODS: We quantified embolism resistance via P50 (xylem pressure inducing 50 % embolism or loss of hydraulic conductivity) in petioles and leaflets of six palm species differing in habitat and phylogenetic relatedness using three techniques: in vivo X-ray-based microcomputed tomography, the in situ flow centrifuge technique and the optical vulnerability method. KEY RESULTS: Our results show that P50 of petioles varies greatly in the palm family, from -2.2 ± 0.4 MPa in Dypsis baronii to -5.8 ± 0.3 MPa in Rhapis excelsa (mean ± s.e.). No difference or weak differences were found between petioles and leaf blades within species. Surprisingly, where differences occurred, leaflets were less vulnerable to embolism than petioles. Embolism resistance was not correlated with conduit size (r = 0.37, P = 0.11). CONCLUSIONS: This study represents the first estimate of drought-induced xylem embolism in palms across biomes and provides the first step towards understanding hydraulic adaptations in long-lived arborescent monocots. It showed an almost 3-fold range of embolism resistance between palm species, as large as that reported in all angiosperms. We found little evidence for hydraulic segmentation between leaflets and petioles in palms, suggesting that when it happens, hydraulic segregation may lack a clear relationship with organ cost or replaceability.


Assuntos
Arecaceae , Embolia , Secas , Humanos , Filogenia , Caules de Planta , Água , Microtomografia por Raio-X , Xilema
7.
J Exp Bot ; 71(3): 1151-1159, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31641746

RESUMO

Drought represents a major abiotic constraint to plant growth and survival. On the one hand, plants keep stomata open for efficient carbon assimilation while, on the other hand, they close them to prevent permanent hydraulic impairment from xylem embolism. The order of occurrence of these two processes (stomatal closure and the onset of leaf embolism) during plant dehydration has remained controversial, largely due to methodological limitations. However, the newly developed optical visualization method now allows concurrent monitoring of stomatal behaviour and leaf embolism formation in intact plants. We used this new approach directly by dehydrating intact saplings of three contrasting tree species and indirectly by conducting a literature survey across a greater range of plant taxa. Our results indicate that increasing water stress generates the onset of leaf embolism consistently after stomatal closure, and that the lag time between these processes (i.e. the safety margin) rises with increasing embolism resistance. This suggests that during water stress, embolism-mediated declines in leaf hydraulic conductivity are unlikely to act as a signal for stomatal down-regulation. Instead, these species converge towards a strategy of closing stomata early to prevent water loss and delay catastrophic xylem dysfunction.

8.
Plant Cell Environ ; 43(3): 548-562, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31850535

RESUMO

Climate change threatens food security, and plant science researchers have investigated methods of sustaining crop yield under drought. One approach has been to overproduce abscisic acid (ABA) to enhance water use efficiency. However, the concomitant effects of ABA overproduction on plant vascular system functioning are critical as it influences vulnerability to xylem hydraulic failure. We investigated these effects by comparing physiological and hydraulic responses to water deficit between a tomato (Solanum lycopersicum) wild type control (WT) and a transgenic line overproducing ABA (sp12). Under well-watered conditions, the sp12 line displayed similar growth rate and greater water use efficiency by operating at lower maximum stomatal conductance. X-ray microtomography revealed that sp12 was significantly more vulnerable to xylem embolism, resulting in a reduced hydraulic safety margin. We also observed a significant ontogenic effect on vulnerability to xylem embolism for both WT and sp12. This study demonstrates that the greater water use efficiency in the tomato ABA overproducing line is associated with higher vulnerability of the vascular system to embolism and a higher risk of hydraulic failure. Integrating hydraulic traits into breeding programmes represents a critical step for effectively managing a crop's ability to maintain hydraulic conductivity and productivity under water deficit.

9.
Tree Physiol ; 39(10): 1736-1749, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31553461

RESUMO

The vulnerability of forest species and tree populations to climate change is related to the exposure of the ecosystem to extreme climatic conditions and to the adaptive capacity of the population to cope with those conditions. Adaptive capacity is a relatively under-researched topic within the forest science community, and there is an urgent need to understand to what extent particular combinations of traits have been shaped by natural selection under climatic gradients, potentially resulting in adaptive multi-trait associations. Thus, our aim was to quantify genetic variation in several leaf and woody traits that may contribute to multi-trait associations in which intra-specific variation could represent a source for species adaptation to climate change. A multi-trait approach was performed using nine Quercus petraea provenances originating from different locations that cover most of the species' distribution range over Europe and that were grown in a common garden. Multiple adaptive differences were observed between oak provenances but also some evolutionary stasis. In addition, our results revealed higher genetic differentiation in traits related to phenology and growth than in those related to xylem anatomy, physiology and hydraulics, for which no genetic differentiation was observed. The multiple associations between those traits and climate variables resulting from multivariate and path analyses suggest a multi-trait association largely involving phenological and growth traits for Q. petraea.


Assuntos
Quercus , Mudança Climática , Ecossistema , Europa (Continente) , Fenótipo
10.
Plant Physiol ; 181(3): 1163-1174, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31455632

RESUMO

Vascular pathogens cause disease in a large spectrum of perennial plants, with leaf scorch being one of the most conspicuous symptoms. Esca in grapevine (Vitis vinifera) is a vascular disease with huge negative effects on grape yield and the wine industry. One prominent hypothesis suggests that vascular disease leaf scorch is caused by fungal pathogen-derived elicitors and toxins. Another hypothesis suggests that leaf scorch is caused by hydraulic failure due to air embolism, the pathogen itself, and/or plant-derived tyloses and gels. In this study, we transplanted mature, naturally infected esca symptomatic vines from the field into pots, allowing us to explore xylem integrity in leaves (i.e. leaf midveins and petioles) using synchrotron-based in vivo x-ray microcomputed tomography and light microscopy. Our results demonstrated that symptomatic leaves are not associated with air embolism. In contrast, symptomatic leaves presented significantly more nonfunctional vessels resulting from the presence of nongaseous embolisms (i.e. tyloses and gels) than control leaves, but there was no significant correlation with disease severity. Using quantitative PCR, we determined that two vascular pathogen species associated with esca necrosis in the trunk were not found in leaves where occlusions were observed. Together, these results demonstrate that symptom development is associated with the disruption of vessel integrity and suggest that symptoms are elicited at a distance from the trunk where fungal infections occur. These findings open new perspectives on esca symptom expression where the hydraulic failure and elicitor/toxin hypotheses are not necessarily mutually exclusive.

12.
J Exp Bot ; 69(22): 5611-5623, 2018 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-30184113

RESUMO

According to the hydraulic vulnerability segmentation hypothesis, leaves are more vulnerable to decline of hydraulic conductivity than branches, but whether stem xylem is more embolism resistant than leaves remains unclear. Drought-induced embolism resistance of leaf xylem was investigated based on X-ray microcomputed tomography (microCT) for Betula pendula, Laurus nobilis, and Liriodendron tulipifera, excluding outside-xylem, and compared with hydraulic vulnerability curves for branch xylem. Moreover, bordered pit characters related to embolism resistance were investigated for both organs. Theoretical P50 values (i.e. the xylem pressure corresponding to 50% loss of hydraulic conductance) of leaves were generally within the same range as hydraulic P50 values of branches. P50 values of leaves were similar to branches for L. tulipifera (-2.01 versus -2.10 MPa, respectively), more negative for B. pendula (-2.87 versus -1.80 MPa), and less negative for L. nobilis (-6.4 versus -9.2 MPa). Despite more narrow conduits in leaves than branches, mean interconduit pit membrane thickness was similar in both organs, but significantly higher in leaves of B. pendula than in branches. This case study indicates that xylem shows a largely similar embolism resistance across leaves and branches, although differences both within and across organs may occur, suggesting interspecific variation with regard to the hydraulic vulnerability segmentation hypothesis.


Assuntos
Betula/anatomia & histologia , Secas , Laurus/anatomia & histologia , Liriodendron/anatomia & histologia , Árvores/anatomia & histologia , Xilema/fisiologia , Betula/fisiologia , Laurus/fisiologia , Liriodendron/fisiologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/citologia , Folhas de Planta/fisiologia , Brotos de Planta/anatomia & histologia , Brotos de Planta/citologia , Brotos de Planta/fisiologia , Árvores/fisiologia , Microtomografia por Raio-X
13.
Tree Physiol ; 38(7): 1016-1025, 2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29474679

RESUMO

Methods to estimate xylem embolism resistance generally rely on hydraulic measurements, which can be far from straightforward. Recently, a pneumatic method based on air flow measurements of terminal branch ends was proposed to construct vulnerability curves by linking the amount of air extracted from a branch with the degree of embolism. We applied this novel technique for 10 temperate tree species, including six diffuse, two ring-porous and two gymnosperm species, and compared the pneumatic curves with hydraulic ones obtained from either the flow-centrifuge or the hydraulic-bench dehydration method. We found that the pneumatic method provides a good estimate of the degree of xylem embolism for all angiosperm species. The xylem pressure at 50% and 88% loss of hydraulic conductivity (i.e., Ψ50 and Ψ88) based on the methods applied showed a strongly significant correlation for all eight angiosperms. However, the pneumatic method showed significantly reduced Ψ50 values for the two conifers. Our findings suggest that the pneumatic method could provide a fast and accurate approach for angiosperms due to its convenience and feasibility, at least within the range of embolism resistances covered by our samples.


Assuntos
Transpiração Vegetal , Árvores/fisiologia , Xilema/fisiologia , Cycadopsida/fisiologia , Magnoliopsida/fisiologia , Caules de Planta/fisiologia
14.
Physiol Plant ; 163(1): 59-72, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29057474

RESUMO

Drought-induced xylem embolism is a key process closely related to plant mortality during extreme drought events. However, this process has been poorly investigated in crop species to date, despite the observed decline of crop productivity under extreme drought conditions. Interspecific variation in hydraulic traits has frequently been reported, but less is known about intraspecific variation in crops. We assessed the intraspecific variability of embolism resistance in four sunflower (Helianthus annuus L.) accessions grown in well-watered conditions. Vulnerability to embolism was determined by the in situ flow-centrifuge method (cavitron), and possible trade-offs between xylem safety, xylem efficiency and growth were assessed. The relationship between stem anatomy and hydraulic traits was also investigated. Mean P50 was -3 MPa, but significant variation was observed between accessions, with values ranging between -2.67 and -3.22 MPa. Embolism resistance was negatively related to growth and positively related to xylem-specific hydraulic conductivity. There is, therefore, a trade-off between hydraulic safety and growth but not between hydraulic safety and efficiency. Finally, we found that a few anatomical traits, such as vessel density and the area of the vessel lumen relative to that of the secondary xylem, were related to embolism resistance, whereas stem tissue lignification was not. Further investigations are now required to investigate the link between the observed variability of embolism resistance and yield, to facilitate the identification of breeding strategies to improve yields in an increasingly arid world.


Assuntos
Helianthus/fisiologia , Secas , Helianthus/anatomia & histologia , Caules de Planta/anatomia & histologia , Caules de Planta/fisiologia , Especificidade da Espécie , Xilema/anatomia & histologia , Xilema/fisiologia
15.
Cell Chem Biol ; 24(3): 360-370, 2017 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-28286129

RESUMO

The main inhibitory neurotransmitter, γ-aminobutyric acid (GABA), modulates many synapses by activating the G protein-coupled receptor GABAB, which is a target for various therapeutic applications. It is an obligatory heterodimer made of GB1 and GB2 that can be regulated by positive allosteric modulators (PAMs). The molecular mechanism of activation of the GABAB receptor remains poorly understood. Here, we have developed FRET-based conformational GABAB sensors compatible with high-throughput screening. We identified conformational changes occurring within the extracellular and transmembrane domains upon receptor activation, which are smaller than those observed in the related metabotropic glutamate receptors. These sensors also allow discrimination between agonists of different efficacies and between PAMs that have different modes of action, which has not always been possible using conventional functional assays. Our study brings important new information on the activation mechanism of the GABAB receptor and should facilitate the screening and identification of new chemicals targeting this receptor.


Assuntos
Transferência Ressonante de Energia de Fluorescência , Receptores de GABA-B/metabolismo , Regulação Alostérica , Cálcio/análise , Cálcio/metabolismo , Agonistas dos Receptores de GABA-B/química , Agonistas dos Receptores de GABA-B/metabolismo , Antagonistas de Receptores de GABA-B/química , Antagonistas de Receptores de GABA-B/metabolismo , Células HEK293 , Humanos , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Receptores de GABA-B/química , Ácido gama-Aminobutírico/química , Ácido gama-Aminobutírico/metabolismo
16.
Nat Chem Biol ; 13(4): 372-380, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28135236

RESUMO

Cell surface receptors represent a vast majority of drug targets. Efforts have been conducted to develop biosensors reporting their conformational changes in live cells for pharmacological and functional studies. Although Förster resonance energy transfer (FRET) appears to be an ideal approach, its use is limited by the low signal-to-noise ratio. Here we report a toolbox composed of a combination of labeling technologies, specific fluorophores compatible with time-resolved FRET and a novel method to quantify signals. This approach enables the development of receptor biosensors with a large signal-to-noise ratio. We illustrate the usefulness of this toolbox through the development of biosensors for various G-protein-coupled receptors and receptor tyrosine kinases. These receptors include mGlu, GABAB, LH, PTH, EGF and insulin receptors among others. These biosensors can be used for high-throughput studies and also revealed new information on the activation process of these receptors in their cellular environment.


Assuntos
Técnicas Biossensoriais , Transferência Ressonante de Energia de Fluorescência , Ensaios de Triagem em Larga Escala , Receptores Proteína Tirosina Quinases/metabolismo , Receptores Acoplados a Proteínas-G/metabolismo , Animais , Células HEK293 , Humanos , Ratos
17.
Dalton Trans ; 44(11): 4791-803, 2015 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-25341077

RESUMO

The development of the brightest luminescent europium(iii) complexes is traced, including analysis of the C3-symmetric core complex based on a functionalized triazacyclononane and identification of the most suitable strongly absorbing chromophore. Strategies for the synthesis of the complexes, including enantiopure analogues, are outlined and opportunities for applications in time-resolved microscopy and spectral imaging emphasised. Practicable examples are introduced, including selective organelle staining for cellular optical imaging at 65 nm resolution and the development of new bioassays using time-resolved FRET methods.


Assuntos
Bioensaio/métodos , Corantes/síntese química , Európio/química , Imagem Óptica/métodos , Compostos Organometálicos/síntese química , Animais , Técnicas de Química Sintética , Corantes/química , Corantes/metabolismo , Humanos , Compostos Organometálicos/química , Compostos Organometálicos/metabolismo
18.
Org Biomol Chem ; 12(40): 8061-71, 2014 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-25184483

RESUMO

The synthesis is described of a series of meta and para-substituted phenylsulfonate derivatives of very bright Eu(III) complexes with arylphosphinate groups and strongly absorbing arylalkynylpyridine moieties. The synthetic route involved the early introduction of trifluoroethyl esters to protect the sulfonic acid group, withstanding the use of reagents including acetyl bromide and mCPBA, and tolerating acid-catalysed esterification and Sonogashira reaction conditions. The Eu(III) complexes exhibit enhanced water solubility; their photophysical properties are not perturbed significantly by introduction of the anionic sulfonate groups.

19.
Angew Chem Int Ed Engl ; 53(40): 10718-22, 2014 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-25115848

RESUMO

Luminescent europium complexes are used in a broad range of applications as a result of their particular emissive properties. The synthesis and application of bright, highly water-soluble, and negatively charged sulfonic- or carboxylic acid derivatives of para-substituted aryl-alkynyl triazacyclononane complexes are described. Introduction of the charged solubilizing moieties suppresses cellular uptake or adsorption to living cells making them applicable for labeling and performing assays on membrane receptors. These europium complexes are applied to monitor fluorescent ligand binding on cell-surface proteins with time-resolved Förster resonance energy transfer (TR-FRET) assays in plate-based format and using TR-FRET microscopy.


Assuntos
Compostos Aza/análise , Complexos de Coordenação/análise , Európio/análise , Transferência Ressonante de Energia de Fluorescência/métodos , Substâncias Luminescentes/análise , Microscopia/métodos , Piperidinas/análise , Receptores Acoplados a Proteínas-G/metabolismo , Compostos Aza/metabolismo , Complexos de Coordenação/metabolismo , Európio/metabolismo , Células HEK293 , Humanos , Ligantes , Substâncias Luminescentes/metabolismo , Piperidinas/metabolismo , Ligação Proteica , Receptores Acoplados a Proteínas-G/análise , Solubilidade , Água/química
20.
Chemistry ; 20(28): 8636-46, 2014 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-24938657

RESUMO

A series of europium and terbium complexes based on a functionalized triazacyclononane carboxylate or phosphinate macrocyclic ligand is described. The influence of the anionic group, that is, carboxylate, methylphosphinate, or phenylphosphinate, on the photophysical properties was studied and rationalized on the basis of DFT calculated structures. The nature, number, and position of electron-donating or electron-withdrawing aryl substituents were varied systematically within the same phenylethynyl scaffold in order to optimize the brightness of the corresponding europium complexes and investigate their two-photon absorption properties. Finally, the europium complexes were examined in cell-imaging applications, and selected terbium complexes were studied as potential oxygen sensors.


Assuntos
Alquinos/química , Compostos Aza/química , Európio/química , Compostos Organometálicos/química , Piperidinas/química , Térbio/química , Ligantes , Estrutura Molecular
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