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Citation
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HERO ID
7622846
Reference Type
Journal Article
Title
Photophysical properties and structural analysis of modified methylene blues as near infrared dyes
Author(s)
Tamoto, A; Aratani, N; Yamada, H; ,
Year
2018
Is Peer Reviewed?
Yes
Journal
Journal of Photochemistry and Photobiology A: Chemistry
ISSN:
1010-6030
EISSN:
1873-2666
Publisher
ELSEVIER SCIENCE SA
Location
LAUSANNE
Page Numbers
441-446
DOI
10.1016/j.jphotochem.2017.10.031
Web of Science Id
WOS:000430883200054
URL
https://linkinghub.elsevier.com/retrieve/pii/S1010603017312832
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Abstract
To study and improve methylene blue (MB) on its physical properties, structural modifications have been implemented. The counter ion exchanged or 3,7-substituted MB derivatives were prepared and the structural investigation by single crystal X-ray analysis has been performed. The positively-charged symmetric structures for MBI, MBPF6, and MBBPh4 were confirmed. The UV-vis absorption spectra for these products are identical to the original MB and exhibit peaks at 655 nm, indicating negligible interactions between the phenothiazine core and the counter anions. According to this behavior, the solubility in the media could be controlled by the counter anion without change of absorption spectrum. On the other hand, 3,7-bis(diphenylamino)phenothiazinium chloride 3 (MB 3) displays remarkably red shifted absorption bands in which the diphenylamine moieties play as a donor part. The absorption peaks strongly depend on the solvent polarity. Curiously MB 3 in halogenated solvents exhibits the largest red shift of the absorption and negative solvatochromism. For instance, MB 3 in CH2I2 illustrates the absorption spectral peak at 729 nm and the edge reaches to 900 nm despite its anthracene-sized compound at the most. Importantly no solvent dependency was observed for the absorption of normal MB so that this is characteristic for MB 3. Hence, this work demonstrates the utility of MB dye as an efficient NIR light harvesting material. (C) 2017 Elsevier B.V. All rights reserved.
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