Electrochromic Organic Compound with Ortho-Substituted Phenyl Cage
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Solution Overview
Problem
Existing electrochromic organic compounds face challenges in achieving high transparency in their colorless state and absorption in a long wavelength region in their colored state, while also maintaining stability under repeated oxidation and reduction reactions.
Innovation Solution
An electrochromic organic compound with a thiophene core skeleton and a phenyl group having ortho substituents is developed, which absorbs light in the ultraviolet region in its neutral state and shifts to a long wavelength region in its oxidized state, ensuring high transparency and stability through steric hindrance and electron-donating substituents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the conjugation length of oligothiophene is increased to achieve absorption in the visible long wavelength region in the colored state, then the absorption edge extends to the visible range in the neutral state, reducing transparency
Solution Approach 1:
The patent introduces a cage structure with ortho-substituted phenyl groups at specific positions of the oligothiophene backbone. This localized structural modification creates steric hindrance that restricts the planarity and conjugation extent only in specific regions, allowing the molecule to maintain high transparency in the neutral state while achieving long wavelength absorption in the oxidized state.
Solution Approach 2:
The patent combines oligothiophene units with ortho-substituted phenyl groups to create a composite molecular structure. This composite design integrates the electrochromic properties of oligothiophene with the steric protection of phenyl cages, achieving both high transparency in the colorless state and stable long wavelength absorption in the colored state.
2Illumination intensity
If electrically conductive polymers are used to achieve colored state through oxidation, then the absorption shifts to long wavelength region, but the neutral state retains visible absorption and insufficient transparency is achieved
Solution Approach 1:
The patent changes the fundamental parameter of conjugation length by using oligothiophene (shorter conjugation) instead of electrically conductive polymers (long conjugation). This parameter change ensures that the neutral state absorbs only in the ultraviolet region, achieving high transparency, while the oxidized state still achieves visible long wavelength absorption through the electrochromic transition.
3Reliability
If oligothiophene compounds with shorter conjugation length are used to improve transparency in the neutral state, then the visible absorption wavelength in the oxidized state shifts to shorter wavelengths (400-600 nm)
Solution Approach 1:
The patent applies local quality modification by introducing the cage structure with ortho-substituted phenyl groups at specific positions. This localized structural feature provides steric protection that stabilizes the radical cation formed during oxidation, enabling the shorter oligothiophene to achieve absorption at longer wavelengths (600 nm or more) in the oxidized state despite the shorter overall conjugation length.
4Reliability
If electrically conductive polymers are used to achieve electrochromic function, then the structure provides some stability through intramolecular delocalization, but the polymers still deteriorate during repetitive oxidation-reduction reactions
Solution Approach 1:
The patent creates a composite molecular structure combining oligothiophene with ortho-substituted phenyl groups. The phenyl groups with ortho substituents form a protective cage structure that provides enhanced steric protection to the radical cation formed during oxidation, significantly improving durability in repetitive oxidation-reduction cycles compared to simple electrically conductive polymers.
Solution Approach 2:
The patent introduces the cage structure with ortho-substituted phenyl groups in advance, before the oxidation-reduction cycles begin. This pre-installed protective structure provides steric shielding that cushions the unstable radical cation from degradation during repetitive electrochemical reactions, preventing deterioration before it can occur.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compound achieves high transparency in its colorless state and absorption in the visible light region in its colored state, with enhanced durability during repetitive oxidation-reduction cycles, suitable for use in electrochromic elements and optical filters.
Implementation Method 1
The optical absorption characteristics (coloration or light transmittance) of electrochromic materials change through an electrochemical oxidation-reduction reaction
Implementation Method 2
Various electrochromic (hereinafter also referred to as 'EC') materials have been reported. The optical absorption characteristics (coloration or light transmittance) of electrochromic materials change through an electrochemical oxidation-reduction reaction
Implementation Method 3
An EC material of an oligothiophene compound described in David D. Graf and Kent R. Mann, Inorganic Chemistry, 1997, 36, 141 has a shorter π-conjugated chain length than electrically conductive polymers. Thus, oligothiophene EC compounds in their neutral state often have an absorption peak in the ultraviolet region and look transparent to the human eye
Data Source
AI summary
An organic compound having the following general formula [1]:wherein A1 and A2 independently denote a hydrogen atom or a substituent,R7 denotes a hydrogen atom or a substituent,R2 to R5 denote a substituent,R1 and R6 independently denote a hydrogen atom or a substituent, andm is 2 or 3.