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Halogen bonding stabilizes a cis ‐azobenzene derivative in the solid state: a crystallographic study
Author(s) -
Saccone Marco,
Siiskonen Antti,
Fernandez-Palacio Franisco,
Priimagi Arri,
Terraneo Giancarlo,
Resnati Giuseppe,
Metrangolo Pierangelo
Publication year - 2017
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520617003444
Subject(s) - azobenzene , synthon , crystallography , cis–trans isomerism , halogen bond , intramolecular force , chemistry , metastability , covalent bond , derivative (finance) , materials science , molecule , stereochemistry , hydrogen bond , organic chemistry , financial economics , economics
Crystals of trans ‐ and cis ‐isomers of a fluorinated azobenzene derivative have been prepared and characterized by single‐crystal X‐ray diffraction. The presence of F atoms on the aromatic core of the azobenzene increases the lifetime of the metastable cis ‐isomer, allowing single crystals of the cis ‐azobenzene to be grown. Structural analysis on the cis ‐azobenzene, complemented with density functional theory calculations, highlights the active role of the halogen‐bond contact (N…I synthon) in promoting the stabilization of the cis ‐isomer. The presence of a long aliphatic chain on the azobenzene unit induces a phase segregation that stabilizes the molecular arrangement for both the trans ‐ and cis ‐isomers. Due to the rarity of cis ‐azobenzene crystal structures in the literature, our paper makes a step towards understanding the role of non‐covalent interactions in driving the packing of metastable azobenzene isomers. This is expected to be important in the future rational design of solid‐state, photoresponsive materials based on halogen bonding.