TY - JOUR

T1 - Water-soluble acidochromic dyes lipophilized with quaternary ammonium cations as tunable hydrogen chromoionophores for polymeric optical sensors

AU - Похвищева, Надежда Викторовна

AU - Прожерин, Илья Сергеевич

AU - Меньшова, Анна Сергеевна

AU - Ванин, Александр Александрович

A2 - Пешкова, Мария Анатольевна

PY - 2025/10/1

Y1 - 2025/10/1

N2 - Colorimetric ion-selective bulk optodes generate an analytical signal using chromoionophores, which are mainly derivatives of acid-base indicators lipophilized by introducing long-chain substituents. However, this method of lipophilization can be cumbersome due to the complex structure of the parent compounds and intricacy of the product purification. Here, we explore a promising approach to increase the lipophilicity of water-soluble acidochromes by ion-pairing them with lipophilic counterions. Lipophilic ion pairs of several sulfonaphthalein dyes with quaternary ammonium cations are synthesized and used as chromoionophores in coextraction-based PVC–DOS optodes. It is shown that the nature of the acidochrome and counterion determine the lipophilicity and acidity of the resulting ion pair. The partition coefficients of the obtained dyes are in the range from 104 to 106. The pKa values for bromothymol and bromophenol blue ion pairs in the polymeric phase are estimated to be 16.0 ± 0.1 and 10.7 ± 0.6, respectively. The predicted and experimental pH-response of the optodes containing synthesized ion pairs is largely independent of the background electrolyte activity in contrast to conventional optodes.

AB - Colorimetric ion-selective bulk optodes generate an analytical signal using chromoionophores, which are mainly derivatives of acid-base indicators lipophilized by introducing long-chain substituents. However, this method of lipophilization can be cumbersome due to the complex structure of the parent compounds and intricacy of the product purification. Here, we explore a promising approach to increase the lipophilicity of water-soluble acidochromes by ion-pairing them with lipophilic counterions. Lipophilic ion pairs of several sulfonaphthalein dyes with quaternary ammonium cations are synthesized and used as chromoionophores in coextraction-based PVC–DOS optodes. It is shown that the nature of the acidochrome and counterion determine the lipophilicity and acidity of the resulting ion pair. The partition coefficients of the obtained dyes are in the range from 104 to 106. The pKa values for bromothymol and bromophenol blue ion pairs in the polymeric phase are estimated to be 16.0 ± 0.1 and 10.7 ± 0.6, respectively. The predicted and experimental pH-response of the optodes containing synthesized ion pairs is largely independent of the background electrolyte activity in contrast to conventional optodes.

KW - Acidity constant

KW - Acidochromic dyes

KW - Chromoionophores

KW - Partition coefficient

KW - Polymeric optodes

KW - Sulfonaphthalein dyes

UR - https://www.mendeley.com/catalogue/113808cb-d7da-3597-ba30-9933b3ffd847/

U2 - 10.1016/j.snb.2025.137794

DO - 10.1016/j.snb.2025.137794

M3 - Article

VL - 440

JO - Sensors and Actuators, B: Chemical

JF - Sensors and Actuators, B: Chemical

SN - 0925-4005

M1 - 137794

ER -