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Simple modification of basic dyes with bulky & symmetric WCAs for improving their solubilities in organic solvents without color change

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ABSTRACT

A simple and easy solubility enhancement of basic dyes was performed with bulky and symmetric weakly coordinating anions (WCAs). The WCAs decreased the ionic character of the dyes by broadening the partial charge distribution and causing a screening effect on the ionic bonding. This new modification with WCAs has advantages in that it has no influence on the optical properties of the dyes. The solubilities of unmodified and modified dyes were tested in several organic solvents. X-ray powder diffraction patterns of the dyes were measured. Color films were prepared with the dyes and their color loci were analyzed to evaluate the optical properties. By the modification with WCAs, commercial basic dyes showed sufficient solubilities for be applied to various applications while preserving their superior optical properties.

No MeSH data available.


Structures of used chemicals.
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f1: Structures of used chemicals.

Mentions: The structures of the used chemicals are shown in Fig. 1. All dyes used in this study were pararosaniline cationic dyes which are widely used due to their high color strength and low cost. Imide-based (BI) and borate-based (BB) anions that have symmetric structures were chosen as counteranions. Anions with symmetric structures can effectively broaden the charge distribution, therefore, the partial charge of dye molecules can be reduced1415. As a result, modified dyes should have sufficient stabilities and low ionic character. In addition, bulky anions produce a screening effect on the ionic bonding region. As such, the modified dyes should not be easily dissolved by positive and negative ions. For these reasons, basic dyes with bulky and symmetric WCAs behave like non-ionic organic molecules. As a result, they show higher solubilities in organic solvents than unmodified basic dyes. Additionally, borate-based asymmetric anion (UB) was used as contrasting group to evidently show the effect of bulkiness and symmetry of introduced counteranion.


Simple modification of basic dyes with bulky & symmetric WCAs for improving their solubilities in organic solvents without color change
Structures of used chemicals.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382776&req=5

f1: Structures of used chemicals.
Mentions: The structures of the used chemicals are shown in Fig. 1. All dyes used in this study were pararosaniline cationic dyes which are widely used due to their high color strength and low cost. Imide-based (BI) and borate-based (BB) anions that have symmetric structures were chosen as counteranions. Anions with symmetric structures can effectively broaden the charge distribution, therefore, the partial charge of dye molecules can be reduced1415. As a result, modified dyes should have sufficient stabilities and low ionic character. In addition, bulky anions produce a screening effect on the ionic bonding region. As such, the modified dyes should not be easily dissolved by positive and negative ions. For these reasons, basic dyes with bulky and symmetric WCAs behave like non-ionic organic molecules. As a result, they show higher solubilities in organic solvents than unmodified basic dyes. Additionally, borate-based asymmetric anion (UB) was used as contrasting group to evidently show the effect of bulkiness and symmetry of introduced counteranion.

View Article: PubMed Central - PubMed

ABSTRACT

A simple and easy solubility enhancement of basic dyes was performed with bulky and symmetric weakly coordinating anions (WCAs). The WCAs decreased the ionic character of the dyes by broadening the partial charge distribution and causing a screening effect on the ionic bonding. This new modification with WCAs has advantages in that it has no influence on the optical properties of the dyes. The solubilities of unmodified and modified dyes were tested in several organic solvents. X-ray powder diffraction patterns of the dyes were measured. Color films were prepared with the dyes and their color loci were analyzed to evaluate the optical properties. By the modification with WCAs, commercial basic dyes showed sufficient solubilities for be applied to various applications while preserving their superior optical properties.

No MeSH data available.