Halogen bonding directed supramolecular assembly in bromo-substituted trezimides and tennimides?

CrystEngComm Pub Date: 2013-12-12 DOI: 10.1039/C3CE42168F

Abstract

Reaction of isophthaloyl dichloride (I) with 2-amino-5-bromopyridine (BrO) and 2-amino-5-bromopyrimidine (26BrO) produces the trimeric (trezimide) and tetrameric (tennimide) imide-based macrocycles (BrIO)3 and (BrIO)4, and (26BrIO)3 and (26BrIO)4, respectively, in one-step and in modest yields. Macrocyclisation (forming 18-/24-membered rings) is facilitated by the imide hinge [O[double bond, length as m-dash]C–N(R)–C[double bond, length as m-dash]O] (R = ortho-N-substituted-pyridine/pyrimidine), though competing reactions also lead to considerable oligomer/polymer formation. The macrocycles (having 3 or 4 Br atoms) lack classical strong hydrogen bonding donors (i.e. N–H, O–H), but contain numerous acceptors (i.e. Naromatic, C[double bond, length as m-dash]O, arene) participating in halogen and weaker hydrogen bonding. Five crystal structures are analysed with the macrocycles typically aggregating through short C–Br?O[double bond, length as m-dash]Ccarbonyl and/or C–Br?Naromatic halogen bonds (Nc ≤ 0.90) and often associated with longer C–Br?H/π(arene) contacts. Of note, (BrIO)3 exhibits three types of Br?O[double bond, length as m-dash]C/π(arene) halogen bonds with Br?H and C–H?O contacts. The C–Br?N/O halogen bonds, in promoting overall aggregation, typically link macrocycles into 1-D halogen bonded chains.

Graphical abstract: Halogen bonding directed supramolecular assembly in bromo-substituted trezimides and tennimides
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