Arylazo-heteroaryl compounds and their use for long-term thermal energy storage
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Solution Overview
Problem
Existing azobenzene derivatives for molecular solar thermal energy storage face challenges with short Z isomer half-life, limited thermal stability at high temperatures, and restricted heat storage at temperatures below 0°C, leading to uncontrolled crystallization and loss of latent heat.
Innovation Solution
Development of arylazopyrazole derivatives with ester-linked hydrocarbon groups that store thermal energy in their metastable Z isomer liquid phase, allowing for optically triggered crystallization and heat release at low temperatures, achieving thermal stability up to two weeks and storing up to 92 kJ/mol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If azobenzene derivatives are used for MOST energy storage, then energy storage capability is achieved, but Z isomer half-life is short leading to limited storage duration
Solution Approach 1:
The patent modifies molecular parameters by replacing phenyl rings with heteroaryl rings (pyrazole, oxazole, isoxazole, thiazole, isothiazole, imidazole) to change the electronic and steric properties of the azo compound. This parameter change in molecular structure extends the Z isomer half-life from seconds/days to much longer durations while maintaining energy storage capability through reversible photoisomerization
Solution Approach 2:
The patent creates composite molecular structures combining azo groups with heteroaryl rings and various functional groups (ester-linked hydrocarbons, fluorinated groups, etc.). These composite structures achieve both long thermal stability of Z isomer and maintained photoswitchability, resolving the contradiction between energy storage and storage duration
2Duration of action of stationary object
If thermal stability of Z isomer is increased, then storage time is extended, but heat storage capacity at low temperatures decreases due to uncontrolled crystallization
Solution Approach 1:
The patent introduces specific local functional groups (ester-linked hydrocarbon groups, fluorinated groups) at particular positions on the heteroaryl rings to locally modify intermolecular interactions. This local quality change prevents uncontrolled crystallization at low temperatures while maintaining overall thermal stability and long storage time
Solution Approach 2:
The patent designs compounds that undergo controlled phase transitions between liquid and solid states. The ester-linked hydrocarbon groups enable the Z isomer to remain in liquid phase at low temperatures, preventing uncontrolled crystallization and allowing heat storage to be maintained below 0°C while extending storage time
3Reliability
If heteroaryl rings are introduced to extend Z isomer half-life, then thermal stability improves, but molecular complexity increases
Solution Approach 1:
The patent systematically varies parameters of heteroaryl rings (different heteroatoms, ring sizes, substitution patterns) to achieve optimal balance between thermal stability and structural simplicity. By changing these parameters, long Z isomer half-life is achieved with relatively simple molecular architectures rather than complex multi-component systems
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 arylazopyrazoles demonstrate remarkable thermal stability of Z isomers at high temperatures and liquid-phase stability below 0°C, enabling prolonged thermal energy storage and controlled heat release, suitable for applications like defrosting and personal heating under extreme cold conditions.
Implementation Method 1
Photo-switching molecular systems including azobenzenes, norbornadienes, dihydroazulenes, and fulvalenediruthenium complexes have been recognized as molecular solar thermal (MOST) energy storage materials that convert photon energy to thermal energy by reversible isomerization and energy storage in a metastable isomeric state
Implementation Method 2
azobenzene derivatives have been particularly well explored as MOST compounds due to a plethora of functionalization methods available and their remarkable E-Z isomerization cyclability
Implementation Method 3
Various forms of MOST materials have been developed incorporating azobenzene groups, including small molecules, oligomers, polymers, carbon nanotubes, graphene oxides, etc.
Data Source
AI summary
The present invention relates to a compound of Formula (I): wherein R1, R2, m, n, p, Q, X, Y, W, and “A” are as described herein. The present invention also relates to a process for preparation of a compound of Formula (I). Also disclosed is a thermal-storage device comprising one or more compounds of Formula (I) and a method of storing energy.