Synthesis and physicochemical studies of some new quinolinoxazine pentamethine cyanine dyes

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• 作者：R.M. Abd El-Aal ; N.M. Saber ; S.M. Mina ; Z.M. Essam ; ^{zahraaessam@yahoo.com}
• 关键词：Quinolinoxazine ; Synthesis ; Electronic absorption spectra ; Fluorescence emission ; Solvatochromic behaviour
• 刊名：Arabian Journal of Chemistry
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：10
• 期：1
• 页码：82-90
• 全文大小：896 K
• 卷排序：10

文摘

Polymethine cyanine dyes belong to a well-known class of organic compounds, which have been used in photography and as information storage in laser technology. A series of novel cyanine dyes were synthesized through the formylation of quinolinium[b,c]1,4-oxazine-chloride salt 1. Reaction of compound 2-chloro-3-formyl-quinolinium[b,c]1,4-oxazine-chloride salt 2 with different molar ratios of 2(4)-methyl substituted heterocyclic in basic catalysis afforded the corresponding 2-chloroquinolinium[b,c]1,4-oxazine-chloride salt-3[2(4)]-dimethine (3a–c), quinolinium[b,c]-1,4-oxazinechloride salt-2,3[2(4)]-pentamethine (4a–c) and quinolino[b,c]1,4-oxazine-6yl[2(4)]-monomethine-/2,3[2(4)]-pentamethine cyanine dyes (5a–c) respectively. The structure of the dyes was characterized by elemental analysis, visible absorption, fluorescence emission, IR, 1H-NMR and mass spectroscopy. The correlations between the structure and properties of these dyes have been studied. A comparison of the visible absorption maxima between compounds 3b, 4b and 5b showed that asymmetrical mono-pentamethine cyanine dye 5b reveals a bathochromic shift than both dimethine 3b and pentamethine cyanine dyes 4b. This could be attributed to the more extensive π-conjugation and increasing number of methine groups in asymmetric pentamethine. All the observations and analytical spectra in this paper support the syntheses of new di-, penta- and mono-/pentamethine cyanine dyes. The absorption spectra of dyes were investigated in organic solvents. The results indicated that the excitation for their colour is a simple charge-transfer from oxygen atom of oxazine nucleus and/or nitrogen atom of pyridine (quinoline) nucleus to N-quaternary salts in di-, penta- and mono-/pentamethine cyanine dyes respectively. These dyes showed positive solvatochromism with increased solvent polarity, which depends on the structure and the type of dye.