Fluorescence Quantum Yields and Their Relation to Lifetimes of Rhodamine 6G and Fluorescein in Nine Solvents: Improved Absolute Standards for Quantum Yields¶

Magde, Douglas; Wong, Roger; Seybold, Paul G.

doi:10.1562/0031-8655(2002)075<0327:fqyatr>2.0.co;2

Cited by 749 publications

(580 citation statements)

References 22 publications

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“…The luminescence quantum yield FF of 1 was determined by relative measurements [20] with respect to the standard value of a solution of Rhodamin 6G in EtOH (FF = 95%) at the excitation wavelength 480 nm. [21] Atomic Force Microscopy (AFM) images were taken with a 5500LS SPM system from Agilent Technologies under ambient conditions. Powder X-ray diffraction (PXRD) measurements for both thermally evaporated thin films and solution grown crystalline films were performed using a modular X-ray powder diffractometer RIGAKU.…”

Section: Resultsmentioning

confidence: 99%

A Compact Tetrathiafulvalene–Benzothiadiazole Dyad and Its Highly Symmetrical Charge‐Transfer Salt: Ordered Donor π‐Stacks Closely Bound to Their Acceptors

Geng

Pfattner

Campos

et al. 2014

Chemistry A European J

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A compact and planar donor-acceptor molecule 1 comprising tetrathiafulvalene (TTF) and benzothiadiazole (BTD) has been synthesised and experimentally characterised by structural, optical and electrochemical methods. Solution processed and thermally evaporated thin films of 1 have also been explored as active material in organic field-effect transistors (OFETs). For these devices, a hole field-effect mobility of FE = (1.3 ± 0.5) ×10-3 cm 2 /Vs and of FE = (2.7 ± 0.4) ×10 -3 cm 2 /Vs could be determined for the solution processed and thermally evaporated thin films, respectively. An intense intramolecular charge-transfer (ICT) transition around 495 nm dominates the optical absorption spectrum of the neutral dyad, which also shows a weak emission from its ICT state. The iodine induced oxidation of 1 leads to a partially oxidised crystalline charge-transfer (CT) salt {(1) 2 I 3 }, and eventually also to a fully oxidized compound {1I 3 } ½I 2 .Single crystals of the former CT compound, exhibiting a highly symmetrical crystal structure, reveal a fairly good room temperature electrical conductivity of the order of 2 S cm -1 . The one-dimensional spin system bears compactly bonded BTD acceptors (spatial localisation of LUMO) along its ridge.

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Section: Resultsmentioning

confidence: 99%

A Compact Tetrathiafulvalene–Benzothiadiazole Dyad and Its Highly Symmetrical Charge‐Transfer Salt: Ordered Donor π‐Stacks Closely Bound to Their Acceptors

Geng

Pfattner

Campos

et al. 2014

Chemistry A European J

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“…F is the relative integrated fluorescence intensity, and OD is the optical density at the exciting wavelength. Rhodamine 6G was chosen as the standard (quantum yield equal to 0.90 in water) (20). Emission spectra were obtained at 25°C using 490 nm excitation while collecting fluorescence from 496 to 800 nm.…”

Section: Fret Efficiency ϭ Imentioning

confidence: 99%

Structure and Conformational Changes in the C-terminal Domain of the β2-Adrenoceptor

Granier

Kim

Shafer

et al. 2007

Journal of Biological Chemistry

143

111

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The C terminus of the ␤ 2 -adrenoceptor (AR) interacts with G protein-coupled receptor kinases and arrestins in an agonist-dependent manner, suggesting that conformational changes induced by ligands in the transmembrane domains are transmitted to the C terminus. We used fluorescence resonance energy transfer (FRET) to examine ligand-induced structural changes in the distance between two positions on the ␤ 2 -AR C terminus and cysteine 265 (Cys-265) at the cytoplasmic end of transmembrane domain 6. The donor fluorophore FlAsH (Fluorescein Arsenical Helix binder) was attached to a CCPGCC motif introduced at position 351-356 in the proximal C terminus or at the distal C terminus. An acceptor fluorophore, Alexa Fluor 568, was attached to Cys-265. FRET analyses revealed that the average distances between Cys-265 and the proximal and distal FlAsH sites were 57 and 62 Å , respectively. These relatively large distances suggest that the C terminus is in an extended, relatively unstructured conformation. Nevertheless, we observed ligand-specific changes in FRET. All ligands induced an increase in FRET between the proximal C-terminal FlAsH site and Cys-265. Ligands that have been shown to induce arrestin-dependent ERK activation, including the catecholamine agonists and the inverse agonist ICI118551, led to a decrease in FRET between the distal FlAsH site and Cys-265, whereas other ligands had no effect or induced a small increase in FRET. Taken together the results provide new insight into the structure of the C terminus of the ␤ 2 -AR as well as ligand-induced conformational changes that may be relevant to arrestin-dependent regulation and signaling.G protein-coupled receptors (GPCRs) 3 are versatile membrane proteins that regulate a wide variety of physiological functions. They respond to a large array of structurally diverse ligands and are the largest group of targets for drug discovery. Structure/function analysis has identified amino acids important for G protein coupling and ligand binding for several well characterized GPCRs, including the ␤-2 adrenoceptor (␤ 2 -AR) (1). Moreover, many of these studies provide support for the accuracy of three-dimensional models of GPCRs based on the high resolution structure of bovine rhodopsin (2). However, few studies have directly addressed the mechanism by which diffusible ligands activate G proteincoupled receptors.The most detailed information about structural changes associated with activation of a GPCR come from studies of rhodopsin. This is in part owing to its natural abundance and biochemical stability relative to other GPCRs. Electron paramagnetic resonance spectroscopy studies provide evidence that photoactivation of rhodopsin involves a rotation and tilting of transmembrane segment 6 (TM6) relative to TM3 (3). Lightinduced conformational changes have also been observed in the cytoplasmic domain spanning TM1 and TM2, and the cytoplasmic end of TM7 (4 -6).Although rhodopsin has long been used as a model system for GPCR activation, it is unique among GPCRs because of...

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“…4,6 However, under alkaline conditions, where the xanthene-related chromophore/fluorophore exists as the anion, φ f is much larger (i.e., 0.92 for fluorescein). 3,6,8 This point is illustrated in Figure 1. Figure 1.…”

Section: Introductionmentioning

confidence: 88%

Aarhus green: a tetrafluoro-substituted derivative of fluorescein

Holmehave¹,

Pedersen²,

Jensen³

et al. 2015

Arkivoc

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Dedicated to Professor Michael Orfanopoulos on the occasion of his 67th birthday ‡ These authors contributed equally to this work.DOI: http://dx.doi.org/10.3998/ark.5550190.p009.011 AbstractThe synthesis and characterization of a 2',4',5',7'-tetrafluorinated derivative of fluorescein, called Aarhus Green, is reported. As with related 2',7'-difluorinated compounds, tetrafluorination of the xanthene-derived moiety makes the more fluorescent anion accessible over a larger pH range. However, in contrast to a published report, we find that fluorination in the 4' and 5' positions does not appreciably decrease the fluorescence quantum yield, φ f . Rather, Aarhus Green has a reasonably large φ f (0.79 ± 0.04). Moreover, Aarhus Green does not efficiently sensitize the production of singlet oxygen and it is photostable. Thus, tetrafluorination of the xanthene moiety in fluorescein derivatives can be a useful tool in the development of fluorescent probes.

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Fluorescence Quantum Yields and Their Relation to Lifetimes of Rhodamine 6G and Fluorescein in Nine Solvents: Improved Absolute Standards for Quantum Yields¶

Cited by 749 publications

References 22 publications

A Compact Tetrathiafulvalene–Benzothiadiazole Dyad and Its Highly Symmetrical Charge‐Transfer Salt: Ordered Donor π‐Stacks Closely Bound to Their Acceptors

A Compact Tetrathiafulvalene–Benzothiadiazole Dyad and Its Highly Symmetrical Charge‐Transfer Salt: Ordered Donor π‐Stacks Closely Bound to Their Acceptors

Structure and Conformational Changes in the C-terminal Domain of the β2-Adrenoceptor

Aarhus green: a tetrafluoro-substituted derivative of fluorescein

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