Halogen-bonded cocrystallization with phosphorus, arsenic and antimony acceptors

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Solid-State Chemistry

Background:

• Non-covalent interactions, including halogen bonds, are crucial for materials design, typically involving small, 2nd-period elements like nitrogen and oxygen.
• Heavier elements, particularly sulfur, have limited roles as halogen bond acceptors in established supramolecular chemistry.

Purpose of the Study:

• To experimentally observe and theoretically study halogen bonds involving heavier pnictogen elements (phosphorus, arsenic, antimony).
• To explore the potential of these interactions in forming novel cocrystals and advancing materials science.

Main Methods:

• Cocrystallization of 1,3,5-trifluoro-2,4,6-triiodobenzene with triphenylphosphine, triphenylarsine, and triphenylstibine.
• Experimental characterization of the resulting cocrystals.
• Theoretical calculations to study the nature and strength of the observed halogen bonds (I···P, I···As, I···Sb).

Main Results:

• Successful formation of cocrystals featuring halogen bonds between iodine and phosphorus, arsenic, and antimony.
• Demonstration that increasingly metallic pnictogens can form sufficiently strong halogen bonds to facilitate cocrystal assembly.
• Observation of colossal thermal expansion in the cocrystal involving I···Sb halogen bonds.

Conclusions:

• Heavier pnictogens can act as effective halogen bond acceptors, expanding the scope of supramolecular chemistry.
• This finding opens new avenues for designing advanced materials with tailored properties, exemplified by significant thermal expansion.
• The study highlights the potential of incorporating heavier elements into supramolecular frameworks for novel material applications.