scholarly journals A Ground-State Complex Between Methyl Viologen and the Fluorescent Whitening Agent 4, 4’–bis (2-sulfostyryl)-biphenyl disodium salt: A Fluorescence Spectroscopy Study

2021 ◽  
Author(s):  
Emily J. Armstrong ◽  
Henry Galas ◽  
R. Stephen Wylie ◽  
Shiva Zohrehvand ◽  
Jan van Stam ◽  
...  
Keyword(s):  
Ground State ◽  
Methyl Viologen ◽  
Disodium Salt ◽  
Static Quenching ◽  
Fluorescent Whitening Agent ◽  
Whitening Agent ◽  
Diffusion Controlled ◽  
Quenching Efficiency ◽  
Spectroscopic Examination ◽  
Fluorescent State

This study explores the quenching of the dianionic fluorescent whitening agent, NFW, by various substances, including methyl viologen (MV), in water and in the presence of Beta-cyclodextrin (β-CD). Results of a fluorescence spectroscopic examination of the β-CD-NFW system are presented. It was found that NFW forms a 1:1 inclusion complex with β-CD with an association constant of 2540 ± 380 M<sup>-1</sup>. The included NFW fluorescent state is protected by the β-CD cavity from a range of water-based quenchers (neutral, anionic and cationic). Quenching proceeds near the diffusion-controlled limit in water for the quenchers tested with the exception of the dicationic MV. MV is an extremely efficient quencher of NFW fluorescence with a nominal K<sub>SV</sub> ~ 5.0x10<sup>3</sup> M<sup>-1</sup> in water alone, corresponding to a nominal k<sub>q</sub> of ~ 4x10<sup>12</sup> M<sup>-1</sup>s<sup>-1</sup>, which exceeds the diffusion-controlled limit in this solvent. The quenching efficiency of MV is strongly suppressed in the presence of 10 mM β-CD (K<sub>SV</sub> = 105 ± 12 M<sup>-1</sup>) and in the presence of NaCl (K<sub>SV</sub> = 106 ± 9 M<sup>-1</sup> at 0.5 M salt). In the absence of CD or salt, there is a strong contribution from static quenching in the MV system; the presence of these additives suppresses the static quenching. Various results suggest the static quenching is due to formation of a ground-state complex between the dianion NFW and the dication MV.

Photochemistry of Free-Base Porphyrin Linked to Methyl Viologen

1992 ◽  
Vol 57 (1) ◽  
pp. 26-32 ◽  
Author(s):  
N. M. Guindy ◽  
F. M. Elzawawy ◽  
D. Y. Sabry
Keyword(s):  
Methyl Viologen ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Phenyl Group ◽  
Laser Flash ◽  
Porphyrin Ring ◽  
Free Base ◽  
Intramolecular Quenching ◽  
Quenching Efficiency ◽  
Triton X

The photochemistry of free-base meso-tetraphenylporphyrin linked to methyl viologen via an alkoxy chain (n = 3) at the ortho, meta or para-position of one meso-phenyl group, in Triton X-100 micellar aqueous solutions is reported. The appended viologen does not quench the porphyrin fluorescence nor its triplet excited state due to the different solubilization of both parts of the molecule in the medium where the porphyrin ring resides in the hydrophobic phase and the alkoxy linker protrudes into the rather diffuse outer phase of detergent oxyethylene units, while the viologen moiety penetrates into the aqueous layer. However, laser flash photolysis measurements show that in the presence of nicotinamide dinucleotide, NADH, the porphyrin ring is reduced to phlorin due to the penetration of NADH into the organic phase. For porphyrin-tetraviologen in which a viologen molecule is linked to each of the porphyrin meso-position via alkoxy chain, fluorescence quenching could be achieved. The values of the quenching efficiency are high (94% in acetonitrile) compared to intramolecular quenching and are dependent upon the solvent viscosity.

The Effect of Fluorescent Whitening Agent on the Coated Ink-Jet Printing Paper

2011 ◽  
Vol 183-185 ◽  
pp. 1692-1695
Author(s):  
Wen Hua Gao ◽  
Ke Fu Chen ◽  
Ren Dang Yang ◽  
Fei Yang ◽  
Xiao Bin Chen
Keyword(s):  
Great Influence ◽  
Chromatic Aberration ◽  
Coated Paper ◽  
Fluorescent Whitening Agent ◽  
Ink Jet Printing ◽  
Whitening Agent ◽  
Ink Jet ◽  
Color Density ◽  
Jet Printing ◽  
Printing Paper

Fluorescent whitening agent is relatively small dosage in the coating, but it has great influence on the properties of the coating and ink-jet printing qualities. With the increase of fluorescent whitening agent dosage, the PH of the coating rose but the viscosity was hardly to change. The brightness of coated ink-jet printing paper and color density of the printing image firstly presented the trend of increasing then decreasing. What’s more, when the brightness of the coated paper achieved to the maximum, color density and contact angle properties were the largest. Chromatic aberration property of the image reduced from 1.87 to 1.75, when the addition of fluorescent whitening agent rose from 0.1% to 0.5%. While the dosage was rose to 0.9%, chromatic aberration increased to 2.15. The gloss of coated paper decreased with the dosage of fluorescent whitening agent increasing. In sum, fluorescent whitening agent can enhance the brightness of the coated paper as well as the printing properties. The results show that the best brightness and printing qualities of coated ink-jet printing paper are obtained, when the fluorescent whitening agent is 0.5%( relative to pigment).

scholarly journals Halogen-Bond Assisted Photoinduced Electron Transfer

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4361
Author(s):  
Bogdan Dereka ◽  
Ina Fureraj ◽  
Arnulf Rosspeintner ◽  
Eric Vauthey
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Ground State ◽  
Halogen Bond ◽  
Quenching Rate ◽  
Excited Complex ◽  
Diffusion Controlled ◽  
Donor Acceptor ◽  
Quenching Rate Constant ◽  
Excited State Population

The formation of a halogen-bond (XB) complex in the excited state was recently reported with a quadrupolar acceptor–donor–acceptor dye in two iodine-based liquids (J. Phys. Chem. Lett. 2017, 8, 3927–3932). The ultrafast decay of this excited complex to the ground state was ascribed to an electron transfer quenching by the XB donors. We examined the mechanism of this process by investigating the quenching dynamics of the dye in the S1 state using the same two iodo-compounds diluted in inert solvents. The results were compared with those obtained with a non-halogenated electron acceptor, fumaronitrile. Whereas quenching by fumaronitrile was found to be diffusion controlled, that by the two XB compounds is slower, despite a larger driving force for electron transfer. A Smoluchowski–Collins–Kimball analysis of the excited-state population decays reveals that both the intrinsic quenching rate constant and the quenching radius are significantly smaller with the XB compounds. These results point to much stronger orientational constraint for quenching with the XB compounds, indicating that electron transfer occurs upon formation of the halogen bond.

Photochemical studies of a sulphonated derivative of 1,3-Diphenyl-2-pyrazoline

1975 ◽  
Vol 28 (9) ◽  
pp. 2083 ◽  
Author(s):  
IH Leaver ◽  
GC Ramsay ◽  
LJ Stephens
Keyword(s):  
Aqueous Solution ◽  
Vinyl Alcohol ◽  
Wool Fibre ◽  
Poly Vinyl Alcohol ◽  
Simulated Sunlight ◽  
Fluorescent Whitening Agent ◽  
Whitening Agent

The photochemistry of the sulphonated pyrazoline fluorescent whitening agent sodium 4-(3?-phenyl-2?-pyrazolin-1?-yl)benzenesulphonate has been examined in aqueous solution, in films of poly(vinyl alcohol) and in the wool fibre. Photooxidation to give the pyrazole occurs almost quantitatively in solution, but accounts for only half of the photoproducts formed in the polymer. In the wool fibre, pyrazole formation accounts for more than half of the pyrazoline whitener destroyed during exposure to simulated sunlight.

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