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QXY7 acid [equivalent to QSY-7 acid]

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Physical properties
Molecular weight771.81
Spectral properties
Absorbance (nm)561
Correction Factor (280 nm)0.22
Extinction coefficient (cm -1 M -1)900001
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
Absorbance (nm)
Correction Factor (280 nm)
Extinction coefficient (cm -1 M -1)
QXY7 is the same molecule to QSY-7 acid (ThermoFisher). QXY7 has a broad and intense absorption at ~550 nm maxima with no detectable fluorescence, making it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications paring with Cy3, TAMRA, Alexa Fluor 555, iFluor 647 or other spectrally similar fluorescent dyes.


Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of QXY7 acid [equivalent to QSY-7 acid] to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

0.1 mg0.5 mg1 mg5 mg10 mg
1 mM129.566 µL647.828 µL1.296 mL6.478 mL12.957 mL
5 mM25.913 µL129.566 µL259.131 µL1.296 mL2.591 mL
10 mM12.957 µL64.783 µL129.566 µL647.828 µL1.296 mL

Molarity calculator

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Spectral properties

Absorbance (nm)561
Correction Factor (280 nm)0.22
Extinction coefficient (cm -1 M -1)900001

Product Family

NameExcitation (nm)Emission (nm)Extinction coefficient (cm -1 M -1)Quantum yieldCorrection Factor (280 nm)Correction Factor (260 nm)
ICG acid789813230000-0.076-
Cy3NS acid *CAS 1032678-01-5*55556915000010.1510.0730.07
Cy5NS acid65167025000010.271, 0.420.030.02
Cy7NS acid7567792500000.30.0360.05
AMCA acid *CAS#: 106562-32-7*34643419000-0.153-
EDANS acid [5-((2-Aminoethyl)amino)naphthalene-1-sulfonic acid] *CAS 50402-56-7*3364555900-0.107-
EDANS acid [5-((2-Aminoethyl)amino)naphthalene-1-sulfonic acid]3364555900-0.107-
DABCYL acid [4-((4-(Dimethylamino)phenyl)azo)benzoic acid] *CAS 6268-49-1*----0.516-
BCECF acid *CAS#: 85138-49-4*50452790000---
XFD532 acid *Same Structure to Alexa Fluor™ 532 acid*534553810000.6110.090.24
XFD488 acid *Same Structure to Alexa Fluor™ 488 acid*499520710000.9210.110.30
Cy3B acid56057112000010.5810.0690.048
XFD350 acid *Same Structure to Alexa Fluor™ 350 acid*34344119000-0.190.25
XFD546 acid *Same Structure to Alexa Fluor™ 546 acid*5615721120000.7910.120.21
XFD568 acid *Same Structure to Alexa Fluor™ 568 acid*579603913000.6910.460.45
XFD514 acid51854380000-0.180.31
XFD555 acid5535681550000.110.080.08
XFD647 acid6506712700000.3310.03-
XFD750 acid7527762900000.1210.04-
XFD700 acid6967192050000.2510.07-
Show More (11)



View all 14 references: Citation Explorer
Structural exploration and Förster theory modeling for the interpretation of gas-phase FRET measurements: Chromophore-grafted amyloid-β peptides.
Authors: Kulesza, Alexander and Daly, Steven and MacAleese, Luke and Antoine, Rodolphe and Dugourd, Philippe
Journal: The Journal of chemical physics (2015): 025101
Action-FRET: probing the molecular conformation of mass-selected gas-phase peptides with Förster resonance energy transfer detected by acceptor-specific fragmentation.
Authors: Daly, Steven and Poussigue, Frédéric and Simon, Anne-Laure and MacAleese, Luke and Bertorelle, Franck and Chirot, Fabien and Antoine, Rodolphe and Dugourd, Philippe
Journal: Analytical chemistry (2014): 8798-804
Fluorescence-based sensing of glucose using engineered glucose/galactose-binding protein: a comparison of fluorescence resonance energy transfer and environmentally sensitive dye labelling strategies.
Authors: Khan, Faaizah and Gnudi, Luigi and Pickup, John C
Journal: Biochemical and biophysical research communications (2008): 102-6
A time-resolved, internally quenched fluorescence assay to characterize inhibition of hepatitis C virus nonstructural protein 3-4A protease at low enzyme concentrations.
Authors: Mao, Shi-Shan and DiMuzio, Jillian and McHale, Carolyn and Burlein, Christine and Olsen, David and Carroll, Steven S
Journal: Analytical biochemistry (2008): 1-8
Longer wavelength fluorescence resonance energy transfer depsipeptide substrates for hepatitis C virus NS3 protease.
Authors: Konstantinidis, Alex K and Richardson, Paul L and Kurtz, Kevin A and Tripathi, Rakesh and Chen, Chih-Ming and Huang, Peggy and Randolph, John and Towne, Danli and Donnelly, Jennifer and Warrior, Usha and Middleton, Tim and Kati, Warren M
Journal: Analytical biochemistry (2007): 156-67
M-DNA: A novel metal ion complex of DNA studied by fluorescence techniques.
Authors: Wettig, Shawn D and Wood, David O and Aich, Palok and Lee, Jeremy S
Journal: Journal of inorganic biochemistry (2005): 2093-101
Short PNA molecular beacons for real-time PCR allelic discrimination of single nucleotide polymorphisms.
Authors: Petersen, Kenneth and Vogel, Ulla and Rockenbauer, Eszter and Nielsen, Kirsten Vang and Kølvraa, Steen and Bolund, Lars and Nexø, Bjørn
Journal: Molecular and cellular probes (2004): 117-22
Fluorescence assay of SIRT protein deacetylases using an acetylated peptide substrate and a secondary trypsin reaction.
Authors: Marcotte, Patrick A and Richardson, Paul L and Richardson, Paul R and Guo, Jun and Barrett, Leo W and Xu, Nan and Gunasekera, Angelo and Glaser, Keith B
Journal: Analytical biochemistry (2004): 90-9
Resonance energy transfer for assessing the molecular integrity of proteins for local delivery.
Authors: Wu, David and Edelman, Elazer R
Journal: Biotechnology and bioengineering (2004): 406-12
Evaluation of the phosphorescent palladium(II)-coproporphyrin labels in separation-free hybridization assays.
Authors: Burke, Martina and O'Sullivan, Paul J and Soini, Aleksi E and Berney, Helen and Papkovsky, Dmitri B
Journal: Analytical biochemistry (2003): 273-80