Halochromic coordination polymers based on a triarylmethane dye for reversible detection of acids

Area of Science:

• Coordination Chemistry
• Materials Science
• Chemical Sensing

Background:

• Chromeazurol B is a pH-sensitive dye with potential for coordination polymer synthesis.
• Hydroxytriarylmethane dyes offer unique functional groups for material design.

Purpose of the Study:

• To synthesize and characterize novel coordination polymers incorporating Chromeazurol B.
• To investigate the pH-sensitive (halochromic) properties of these new materials.
• To explore their potential as multifunctional sensor materials.

Main Methods:

• Solvothermal synthesis of coordination polymers.
• Single-crystal X-ray diffraction for structural analysis.
• Diffuse reflectance spectroscopy and FT-IR for characterization of color changes.
• Investigation of halochromic properties in response to HCl vapors.

Main Results:

• Two new coordination polymers, [NaZn4(H2O)3(L)3]·3THF·3H2O (1) and [Zn3(H2O)3(μ2-OH2)(μ3-OH)(HL)2(H2L)]·2THF·3H2O (2), were successfully synthesized.
• Compound 1 exhibits a layered honeycomb structure, while compound 2 forms a double-chain ribbon.
• Both compounds demonstrate visual pH-sensitivity in aqueous solutions, with compound 1 showing reversible color changes from violet-grey to orange and pink upon exposure to HCl vapors.
• Structural analysis confirmed the coordination of Chromeazurol B anions in different color states.

Conclusions:

• The study presents the first examples of halochromic coordination polymers.
• Compound 1 displays remarkable acid stability and reversible color changes, making it a promising candidate for sensor applications.
• The findings pave the way for designing new multifunctional sensor materials based on halochromic coordination polymers.