Intramolecular Quenching of the Photofading of Some Dyes

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.

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Efficient intramolecular quenching and electron transfer in tetraphenylporphyrin attached with benzoquinone or hydroquinone as a photosystem model

Tetrahedron Letters ◽

10.1016/s0040-4039(01)85940-2 ◽

1979 ◽

Vol 20 (3) ◽

pp. 257-260 ◽

Cited By ~ 52

Author(s):

Iwao Tabushi ◽

Noboru Koga ◽

Mitsuhiro Yanagita

Keyword(s):

Electron Transfer ◽

Intramolecular Quenching

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Photocontrolled multiple-state photochromic benzo[b]phosphole thieno[3,2-b]phosphole-containing alkynylgold(I) complex via selective light irradiation

Nature Communications ◽

10.1038/s41467-021-27711-9 ◽

2022 ◽

Vol 13 (1) ◽

Author(s):

Nathan Man-Wai Wu ◽

Maggie Ng ◽

Vivian Wing-Wah Yam

Keyword(s):

Excited States ◽

Smart Materials ◽

Storage Capacity ◽

Optical Memory ◽

Color Changes ◽

Intramolecular Quenching ◽

Environmental Friendly ◽

Multiple State ◽

Complex Features ◽

Photochromic Materials

AbstractPhotochromic materials have drawn growing attention because using light as a stimulus has been regarded as a convenient and environmental-friendly way to control properties of smart materials. While photoresponsive systems that are capable of showing multiple-state photochromism are attractive, the development of materials with such capabilities has remained a challenging task. Here we show that a benzo[b]phosphole thieno[3,2‑b]phosphole-containing alkynylgold(I) complex features multiple photoinduced color changes, in which the gold(I) metal center plays an important role in separating two photoactive units that leads to the suppression of intramolecular quenching processes of the excited states. More importantly, the exclusive photochemical reactivity of the thieno[3,2‑b]phosphole moiety of the gold(I) complex can be initiated upon photoirradiation of visible light. Stepwise photochromism of the gold(I) complex has been made possible, offering an effective strategy for the construction of multiple-state photochromic materials with multiple photocontrolled states to enhance the storage capacity of potential optical memory devices.

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