Environment-sensitive indolenine-based hemisquaraine dyes: Synthesis, molecular structure, and spectral properties

• Published in: Dyes and pigments 2023-11, Vol.219, p.111612, Article 111612
• Main Authors: Svoiakov, Rostyslav P., Kulyk, Olesia G., Hovor, Iryna V., Shishkina, Svitlana V., Tatarets, Anatoliy L.
• Format: Article
• Language: English
• Subjects: Environment sensors; Hemisquaraine dyes; Molecular rotors; pH-sensitive dyes; Polarity sensors; Viscosity sensors
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2023.111612

Environment-sensitive fluorescent dyes are widely used in biomedical research, clinical diagnostics, molecular and cellular biology, analytical and bioanalytical chemistry. Many sensing dyes in the series of cyanines, styryls, BODIPY, squaraines, fluoresceins, and rhodamines among others have been developed and employed for these applications. Meanwhile, push-pull hemisquaraine dyes have been only moderately explored as the environment sensors. Herein, we developed a series of hemisquaraine dyes containing methylamino (MeH), dimethylamino (MeMe), phenylamino (PhH), phenylmethylamino (PhMe), and diphenylamino (PhPh) groups. These substituents were found to strongly affect sensitivity of the dyes towards H-bond formation, polarity, pH, viscosity, and the presence of bovine serum albumin (BSA), which aids the development of sensors for particular applications. [Display omitted] •A series of new monosquaraine dyes with substituted amino groups was synthesized.•These substituents affect independent sensitivity of the dyes to medium parameters.•Methylamino and phenylamino derivatives are sensitive to H-bonding and acidity.•Dimethylamino and diphenylamino derivatives are sensitive to polarity and viscosity.•Phenylmethylamino derivative is sensitive towards the presence of albumin (BSA).