Single-Component Conductors: A Sturdy Electronic Structure Generated by Bulky Substituents

Area of Science:

• Materials Science
• Solid-State Chemistry
• Organic Electronics

Background:

• Bulky substituents are typically avoided in molecular metals to maximize orbital overlap.
• Crystal engineering strategies using sterically hindered groups are underexplored in single-component conductors.
• Understanding steric effects is crucial for designing novel molecular conductors with tailored properties.

Purpose of the Study:

• To investigate the impact of steric bulk on the solid-state structure and conductivity of molecular metals.
• To synthesize and characterize a novel single-component molecular conductor, [Au(iPr-thiazdt)2], featuring isopropyl substituents.
• To explore the pressure-dependent electronic behavior and phase transitions of the new material.

Main Methods:

• Synthesis of the novel [Au(iPr-thiazdt)2] complex.
• Single-crystal X-ray diffraction to determine the solid-state structure.
• Electrical transport measurements under varying pressure.
• Optical spectroscopy to probe electronic transitions.

Main Results:

• A unique three-dimensional network structure of crisscrossing molecules was observed in [Au(iPr-thiazdt)2].
• The material exhibits weak conductivity (5 S·cm(-1)) at ambient pressure.
• A pressure-induced decrease in the energy gap was observed, with a regime change around 1.5 GPa.
• The Mott insulating state remained stable up to 4 GPa, unlike other conducting systems.

Conclusions:

• Steric bulk, introduced via isopropyl groups, leads to a novel 3D molecular packing in [Au(iPr-thiazdt)2].
• The compound displays unique electronic properties, maintaining a Mott insulating state under significant pressure.
• This work demonstrates the potential of crystal engineering with bulky substituents in designing advanced molecular conductors.