1,4-Dihydropyrrolo[3,2-b]pyrroles as Anodically Coloring Electrochromes

Disciplines

Materials Chemistry | Organic Chemistry

Abstract (300 words maximum)

Cathodically coloring electrochromes have been primarily used for organic electronic applications in anti-glare mirrors and windows, smart windows, and smart sunglasses. However, in practice, these materials have a residual red-light absorbance leaving a blue tint in the films. Anodically coloring electrochromes (ACE) provide a solution to this problem because they are colorless in the neutral state, and upon oxidation are colored. The Collier Research Group uses 1,4-dihydropyrrolo[3,2-b]pyrroles (DHPP) because they are synthetically simple and highly tailorable, thus, highly applicable to organic electronic applications. Guided by time-dependent density functional theory, DHPP molecules functionalized with methoxy and fluorinated functional groups were synthesized to understand the relationship between calculated and experimental optical and electrochemical properties. Following the successful synthesis, optical and electrochemical properties were confirmed via ultraviolet-visible absorbance spectroscopy (UV-vis), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The 4-methoxy DHPP exhibited a redshift in absorbance upon oxidation, transitioning from a colorless neutral compound to a pale yellow/green solution when oxidized. Electrochemical measurements revealed the methoxy-containing DHPP possesses a low onset of oxidation (~0.35 V vs Ag/AgCl) while the fluorinated DHPP possesses a relatively high onset of oxidation (~1.1 V vs. Ag/AgCl). Subsequently, the fluorinated DHPP did not oxidize or change color during the UV-vis titration experiments. Ultimately, these results demonstrate the methoxy-DHPP to be a suitable molecule for ACE applications and provides important structure-property relationships for the continued development of this novel class of materials.

Academic department under which the project should be listed

Chemistry and Biochemistry

Primary Investigator (PI) Name

Graham S. Collier

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1,4-Dihydropyrrolo[3,2-b]pyrroles as Anodically Coloring Electrochromes

Cathodically coloring electrochromes have been primarily used for organic electronic applications in anti-glare mirrors and windows, smart windows, and smart sunglasses. However, in practice, these materials have a residual red-light absorbance leaving a blue tint in the films. Anodically coloring electrochromes (ACE) provide a solution to this problem because they are colorless in the neutral state, and upon oxidation are colored. The Collier Research Group uses 1,4-dihydropyrrolo[3,2-b]pyrroles (DHPP) because they are synthetically simple and highly tailorable, thus, highly applicable to organic electronic applications. Guided by time-dependent density functional theory, DHPP molecules functionalized with methoxy and fluorinated functional groups were synthesized to understand the relationship between calculated and experimental optical and electrochemical properties. Following the successful synthesis, optical and electrochemical properties were confirmed via ultraviolet-visible absorbance spectroscopy (UV-vis), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The 4-methoxy DHPP exhibited a redshift in absorbance upon oxidation, transitioning from a colorless neutral compound to a pale yellow/green solution when oxidized. Electrochemical measurements revealed the methoxy-containing DHPP possesses a low onset of oxidation (~0.35 V vs Ag/AgCl) while the fluorinated DHPP possesses a relatively high onset of oxidation (~1.1 V vs. Ag/AgCl). Subsequently, the fluorinated DHPP did not oxidize or change color during the UV-vis titration experiments. Ultimately, these results demonstrate the methoxy-DHPP to be a suitable molecule for ACE applications and provides important structure-property relationships for the continued development of this novel class of materials.