Synthesis, crystal structure, polymorphism and microscopic luminescence properties of anthracene derivative compounds

TL;DR

This study investigates the crystal structures and luminescence properties of anthracene derivatives, revealing a new polymorph and how molecular packing influences optical behavior, advancing their application in optoelectronics.

Contribution

The paper provides detailed structural analysis of anthracene derivatives, including a newly identified polymorph, and links intermolecular interactions to optical properties, enhancing understanding for optoelectronic applications.

Findings

Identification of a new polymorph via X-ray diffraction.

Shifting substituents affects c0-c0 interactions and optical properties.

Crystallographic and optical data link molecular packing to luminescence.

Abstract

Anthracene derivative compounds are currently investigated because of their unique physical properties (e.g., bright luminescence and emission tunability), which make them ideal candidates for advanced optoelectronic devices. Intermolecular interactions are the basis of the tunability of the optical and electronic properties of these compounds, whose prediction and exploitation benefit from the knowledge of the crystal structure and the packing architecture. Polymorphism can occur due to the weak intermolecular interactions, asking for detailed structural analysis clarifying the origin of observed material property modifications. Here, two silylethyne-substituted anthracene compounds are characterized by single-crystal synchrotron X-ray diffraction, identifying a new polymorph. Additionally, laser confocal microscopy and fluorescence lifetime imaging microscopy confirm the results obtained by the X-ray diffraction characterization, i.e., shifting the substituents towards the external benzene rings of the anthracene unit favours {\pi}-{\pi} interactions, impacting on both the morphology and the microscopic optical properties of the crystals. The compounds with more isolated anthracene units feature shorter lifetime and emission spectra more similar to those ones of isolated molecules. The crystallographic study, supported by the optical investigation, sheds light on the influence of non-covalent interactions on the crystal packing and luminescence properties of anthracene derivatives, providing a further step towards their efficient use as building blocks in active components of light sources and photonic networks.