2,3-difluoro-4″-heptyl-4-pentylterphenyl

Description

2,3-difluoro-4″-heptyl-4-pentylterphenyl 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: KC1018
• CAS number: 121218-85-7
• 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 65.5 SmI 74.5 SmC 118.5 SmA 135.0 N 137.0 °C I

Reading that sequence, in order of increasing temperature:

• Crys – crystalline solid
• SmI – smectic I – tilted, hexatic in-plane order
• SmC – smectic C – layered, molecules tilted to the layer normal
• SmA – smectic A – layered, molecules normal to the layers
• N – nematic – orientational order without layers
• I – isotropic liquid

The mesophase window spans roughly 71.5 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
• reference material for calibrating transition temperatures and optical measurements
• alignment-layer and surface-anchoring studies
• thermally addressed and polymer-dispersed liquid crystal formulations

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.

Please quote CAS 121218-85-7 or catalogue code KC1018 when enquiring, so that the correct isomer is supplied.

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.