Insights into light transmission through 2,5-bis(arylethynyl)pyrazine based crystals: a combined experimental and theoretical study

Abstract

In the field of optical nano/micro waveguides, the ability to modulate the crystal structure and understand the relationship between structure and waveguide properties is a crucial aspect of significant interest. These factors play a vital role in the design of materials capable of transmitting light with the highest possible efficiency. In this work, crystals and co-crystals based on 2,5-bis(arylethynyl)pyrazines have been synthesized. The introduction of functional groups of diverse electronic nature in different positions, as well as the formation of co-crystals with 1,4-diiodotetrafluorobenzene (F₄DIB) as a co-assembler, enabled crystalline structures with different morphologies and good optical waveguide properties to be obtained. Additionally, aspects of paramount importance in light transmission have been studied, including morphology, crystal parameters such as packing arrangement, aggregate types, intermolecular distances, the presence of microchannels in the crystal, and the relationship between the direction of the molecular transition dipole moment and the propagating electric field.