Tetracyclic Liquid Crystal Compound with Diatomic Bonding
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Solution Overview
Problem
Current liquid crystal compounds lack optimal physical properties such as high stability to heat and light, wide temperature range, low viscosity, suitable optical and dielectric anisotropy, and compatibility, which are essential for efficient operation in liquid crystal display devices.
Innovation Solution
A liquid crystal compound represented by formula (1) with specific alkyl and alkenyl groups, ring structures, and bonding configurations is developed, providing improved stability, compatibility, and dielectric anisotropy, and is used in a composition that balances physical properties for enhanced performance in liquid crystal display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid crystal compounds are used, then the device structure is simple, but the physical properties such as stability, viscosity, and dielectric anisotropy are insufficient
Solution Approach 1:
The patent employs composite molecular structures combining tetracyclic ring systems with various functional groups (fluorophenylene, cyclohexylene, alkenyl chains) to achieve superior physical properties. This composite approach allows the liquid crystal compound to exhibit enhanced stability, appropriate viscosity, and large negative dielectric anisotropy while maintaining operational functionality in display devices.
Solution Approach 2:
The patent systematically varies molecular parameters including ring structures (tetracyclic, bicyclic, tricyclic), terminal groups (alkyl, alkenyl, fluorinated groups), and bonding configurations to optimize physical properties. By adjusting these parameters, the compound achieves high stability to heat and light, controlled viscosity, and large negative dielectric anisotropy without excessive structural complexity.
2Reliability
If liquid crystal compounds with high dielectric anisotropy are developed, then the threshold voltage decreases, but the compatibility with other liquid crystal compounds deteriorates
Solution Approach 1:
The patent introduces specific functional groups at terminal positions (fluorinated groups, alkenyl chains) while maintaining a core tetracyclic structure. This local modification approach allows the compound to exhibit large negative dielectric anisotropy through the terminal groups while the core structure ensures compatibility with other liquid crystal compounds through favorable intermolecular interactions.
Solution Approach 2:
The patent adjusts the dielectric anisotropy parameter by modifying terminal group composition (fluorine content, chain length) while keeping the core tetracyclic structure constant. This parameter optimization achieves large negative dielectric anisotropy for low threshold voltage operation while maintaining compatibility through the consistent core structure that interacts favorably with other liquid crystal components.
3Productivity
If liquid crystal compounds with low viscosity are used, then the response time shortens, but the temperature range of liquid crystal phase narrows
Solution Approach 1:
The patent combines rigid tetracyclic ring structures with flexible alkenyl terminal chains to create a composite molecular architecture. The rigid core maintains high melting point and wide temperature range, while the flexible terminal chains reduce viscosity for fast response. This composite structure successfully balances both requirements.
Solution Approach 2:
The patent optimizes the balance between molecular rigidity and flexibility by adjusting the length and saturation of terminal chains. The tetracyclic core provides thermal stability and wide temperature range, while controlled addition of alkenyl groups with specific carbon chain lengths reduces viscosity without excessively lowering the clearing point, achieving both short response time and wide operating temperature range.
Data Source
AI summary
A means is a compound represented by formula (1), a liquid crystal composition containing the compound, and a liquid crystal display device including the composition. R1 and R2 are independently alkyl having 1 to 15 carbons or the like; ring A1, ring A2 and ring A3 are independently 1, 4-cyclohexylene, 1,4-phenylene or the like; and Z1, Z2 and Z3 are independently a single bond or the like.