Document Type

Article

Publication Date

7-1-2022

Publication Title

Crystal Growth & Design

Volume

2023

Issue

23

First Page

1281

Keywords

Anions, Cations, Cavities, Reaction mechanisms, Receptors

Last Page

1287

Abstract

Doubly and triply deprotonated 2-bromo-C-alkylresorcinarene anions form host–guest complexes with both tetramethylammonium cations and bis-protonated dimethyl piperazine cations. The trianion forms a fully closed dimeric capsule with one endo- and two exo-cavity bis-protonated dimethyl piperazine cations. Interestingly, the dianion crystallized from a mixture of the 2-bromo-C-methylresorcinarene, dimethylethylenediamine, and tetramethylammonium chloride forms a nanotube consisting of only the 2-bromo-C-methylresorcinarene anion and the tetramethylammonioum cation. The nanotube has an exo-functionalized anionic hydrophilic outer surface that interacts with cationic guests and a hydrophobic interior channel. Solution studies support the deprotonation and the formation of these host–guest complexes. Quantification of binding in chloroform shows a very strong binding constant between the 2-bromo-C-pentylresorcinarene and tetramethylammonium chloride (K1 = 3.63 × 105 M–1, K2 = 2.32 × 104 M–1), far higher than that observed for the unfunctionalized C-pentylresorcinarene (K1 = 5.10 × 104 M–1, K2 = 1.30 × 103 M–1). We attribute this to the stronger ion-pair in the former as the halogen increases the acidity of the phenolic hydroxyl groups.

DOI

https://doi.org/10.1021/acs.cgd.2c00325

ISSN

1528-7483

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