Synthesis, π-Stacking and Application of Tetraethynyl Dioxotriangulenes

Overview

4,8-Dioxotriangulene (DOT) derivatives with tetraethynyl substitution patterns are investigated as n-type organic semiconductor materials. The study establishes DOT as a viable molecular scaffold for organic electronics through synthesis, structural characterization, and functional evaluation in field-effect transistor devices.

Methods and approach

Three tetraethynyl DOT variants (1a–c) with differing silyl and alkyl protecting groups were synthesized via palladium-catalyzed C(Ar)–O bond activation of phenolic ester precursors. Structural organization was elucidated using single-crystal X-ray diffraction. Electrochemical properties were assessed through cyclic voltammetry and reduction protocols. Radical anion stability was confirmed by electron paramagnetic resonance spectroscopy and ultraviolet–visible absorption spectroscopy. Semiconductor performance was evaluated in solution-processed thin-film field-effect transistor geometries.

Key Findings

Tetraethynyl DOT derivatives 1a and 1b demonstrated distinct solid-state π-stacking architectures. Compound 1a assembled into discrete tetrameric units via π–π interactions, while 1b formed one-dimensional columnar stacks with substantial interplanar orbital overlap. Electrochemical reduction of 1b generated a persistent radical anion species, confirming stabilization of negative charge and spin density across the extended π-conjugated framework. The radical anion remained stable under characterization conditions, as confirmed by spectroscopic methods. Solution-processed thin films of 1b exhibited n-type semiconductor behavior in field-effect transistor configurations, demonstrating hole-blocking and electron-transport characteristics.

Implications

The results establish DOT as a practical molecular platform for n-type organic semiconductor design, particularly through rational control of peripheral substitution to modulate solid-state packing architecture. The ability to generate and stabilize radical anion species indicates favorable redox properties for electron-transport applications. The successful demonstration of n-type field-effect transistor performance in solution-processed films indicates potential utility in organic optoelectronics and flexible device technologies.

Scope and limitations

This summary is based on the study abstract and available metadata. It does not include a full analysis of the complete paper, supplementary materials, or underlying datasets unless explicitly stated. Findings should be interpreted in the context of the original publication.