2′,3′-difluoro-4-heptyl-4”-pentyl-[1,1′;4′,1”]terphenyl

Description

2′,3′-difluoro-4-heptyl-4”-pentyl-[1,1′;4′,1”]terphenyl is a calamitic (rod-shaped) mesogen based on a terphenyl core terminated by a pentyl chain, with two lateral fluorines on adjacent ring positions. Molecules of this shape share a common director, and that orientational order – fluid in position, ordered in direction – is what a liquid crystal device switches.

Key data

• Catalogue code: KC1020
• Molecular formula: C30H36F2
• Molecular weight: 434.6 g/mol
• Category: Liquid Crystals

What the substitution pattern does

The pentyl chain places this compound at n=5 in its homologous series. Chain length is not a cosmetic variable here: each added methylene lowers the melting point unevenly and shifts the balance between nematic and smectic order, because an odd-numbered chain sets its terminal bond at a different angle to the molecular long axis than an even one. Homologues therefore alternate in behaviour rather than trending smoothly, and an odd-numbered member frequently outperforms both of its neighbours for a given formulation.

Two fluorines on adjacent ring positions point their combined dipole across the molecular long axis, not along it. Lateral 2,3-difluorination is the standard route to negative dielectric anisotropy – the property required by vertically aligned display modes, where the field must reorient molecules that start out perpendicular to the substrate.

Three linked rings extend the rigid core further than a biphenyl, raising birefringence and clearing point together. The price is a higher melting point, which is why terphenyls appear as high-birefringence additives to mixtures rather than as single-component materials.

Phase behaviour

Transition sequence measured for this compound:

Crys 36.5 (SmC 24.0) N 111.5 °C I

Reading that sequence, in order of increasing temperature:

• Crys – crystalline solid
• SmC – smectic C – layered, molecules tilted to the layer normal
• N – nematic – orientational order without layers
• I – isotropic liquid

The mesophase window spans roughly 75.0 K above the melting point. Width of that window, not its position alone, decides whether a compound is usable neat or only as one component of a eutectic mixture.

Typical applications

• formulation of negative-dielectric-anisotropy mixtures for VA display modes
• extension of rigid-core length in high-birefringence blends
• alignment-layer and surface-anchoring studies
• thermally addressed and polymer-dispersed liquid crystal formulations
• nematic and smectic host mixtures for display and photonic devices

Ordering

This compound is supplied to order. Pricing depends on quantity and on the specification you need, so it is quoted rather than listed – send an enquiry stating the quantity and any purity or analytical requirement, and you will receive a written quotation.

Handling and documentation

Supplied for laboratory and industrial use by trained personnel only. Not for use as a medicine, food, cosmetic or biocide, and not for administration to humans or animals. Safety documentation is issued with the order; this page is not a source of hazard information.