A world beyond hydrogen bonds? -Chalcogen-chalcogen interactions yielding tubular structures

Area of Science:

• Solid-state chemistry
• Supramolecular chemistry
• Materials science

Background:

• Chalcogen-chalcogen (X...X) interactions are crucial in solid-state chemistry.
• Cyclic and acyclic systems containing sulfur, selenium, and tellurium offer unique structural possibilities.
• The self-assembly of molecular building blocks into extended structures is a key area of research.

Purpose of the Study:

• To demonstrate the formation of tubular structures in the solid state driven by chalcogen-chalcogen contacts.
• To present examples of cyclic sulfur and selenium systems exhibiting these tubular arrangements.
• To investigate the inclusion of guest molecules within these novel tubular structures.

Main Methods:

• Synthesis and characterization of various cyclic and acyclic chalcogen-containing compounds.
• Single-crystal X-ray diffraction analysis to determine solid-state structures.
• Analysis of intermolecular interactions, specifically chalcogen-chalcogen contacts.

Main Results:

• Tubular structures are formed through close chalcogen-chalcogen (X...X) contacts in the solid state.
• Cyclic systems with ring sizes of 24-33 and acyclic systems like 2,7-ditelluraocta-3,5-diyne form zigzag, ladder-type, or helical tubes.
• These tubes successfully include hydrocarbon guest molecules, such as n-hexane.
• The driving force for X...X contacts is identified as np(X)-sigma*(X-C) interactions.

Conclusions:

• Close chalcogen-chalcogen contacts are a viable strategy for constructing tubular architectures in the solid state.
• The size and nature of the chalcogen centers influence the resulting tubular structure (e.g., helical vs. zigzag).
• The ability of these tubes to encapsulate guest molecules highlights their potential for host-guest chemistry and materials applications.