Dimeric tetrabromo-p-quinodimethanes: synthesis and structural/electronic properties

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Tetrabromo-p-quinodimethanes (TBQs) are under-explored molecular building blocks.
• Novel TBAQ dimers (TBQ1-5) with π-conjugated linkers were synthesized and characterized.

Purpose of the Study:

• To investigate the structural, electronic, and dynamic properties of novel TBAQ dimers.
• To explore the influence of π-conjugated linkers on electronic communication between TBAQ units.
• To assess the potential of these compounds as precursors in organic synthesis and materials science.

Main Methods:

• Synthesis and full characterization of five TBAQ dimers (TBQ1-5).
• Spectroscopic measurements (NMR, Raman, UV-vis) and theoretical calculations (first-principles).
• Assessment of sublimation, self-assembly, and reactivity on Au(111) for TBQ3.

Main Results:

• TBAQ fragments exhibit a warped, butterfly-like geometry due to steric hindrance from bromine atoms.
• Complex NMR spectra suggest the presence of three stereoisomers (two diastereomers) and fluxional inversion.
• Linker's rotational freedom modulates electronic properties and communication between TBAQ moieties.

Conclusions:

• The synthesized TBAQ dimers possess unique structural and dynamic characteristics.
• These compounds demonstrate potential as versatile building blocks for advanced materials and organic synthesis.
• Further studies on their self-assembly and reactivity are warranted.