Benzene Triimide Cage as a Selective Container of Azide

Abstract

Benzene triimide (BTI, or mellitic triimide) is a C 3-symmetric backbone with a highly electron-deficient, extended π surface and three easy functionalization sites. Here, we report the first BTI-based cage composed of two face-to-face BTIs pillared by three m-xylylene spacers and efficient and selective binding of azide through cooperative anion−π interactions. The cage was easily synthesized in two steps from benzene triimide. Crystal structures showed that the two BTI planes can be separated at about 5–6 Å and form a well-defined electron-deficient cavity. Among a series of anions tested, the cage was found able to bind N3 –, SCN–, and I–. In particular, the binding toward N3 – is very strong (K a = 11098 ± 46 M–1) and highly selective, over 150 and 250 times higher than SCN– and I–, respectively. The control single BTI, however, showed only very weak binding (K a < 5 M–1). The crystal structure showed that N3 – is tightly trapped within the cavity through multiple, very short anion−π interactions. The slow enter–release of N3 – from the cavity was observed in the NMR. The charge-transfer and electron-transfer character of the interactions was also discussed.

Synthesis ofi‐Corona[6]arenes for Selective Anion Binding: Interdependent and Synergistic Anion–π and Hydrogen‐Bond Interactions

“…We showed previously that 1,3‐alternate oxacalix[2]arene[2]triazine 1 [26, 27] (Figure 1) is a unique electron‐neutral receptor for anions owing to its V‐shaped cleft to accommodate an anion by the formation of anion–π interactions between anion and triazine rings [14, 17] . The anion‐π interactions in complexation of oxacalix[2]arene[2]triazine derivatives with anions have also been demonstrated successfully in the fabrication of assembled structures, [23, 24] responsive vesicles [23] and anion sensing systems [22, 28] . Seeking for anion receptors which would also serve as the potential building units for the construction of artificial anion channels, we have recently devised coronarenes, [29–34] a new type of macrocyclic compounds.…”

Synthesis ofi‐Corona[6]arenes for Selective Anion Binding: Interdependent and Synergistic Anion–π and Hydrogen‐Bond Interactions

“…Anion-p interactions, [10][11][12] attraction between chargeneutral electron-deficient aromatic systems and anions,h ave been recognized as the nascent and important non-covalent bond interactions since the generality,b inding strength and binding models were unveiled experimentally [13][14][15][16][17] and computationally [18][19][20] in recent years.T hey have been utilized as the driving force to enable anion recognition and sensing, [21,22] molecular assembly [23,24] and catalysis. [12,25] Notably,i nt he typical anion-p interaction motif,t he anion is located just above the centroid of electron-deficient aromatic ring.…”

“…[14,17] Thea nion-p interactions in complexation of oxacalix [2]arene [2]triazine derivatives with anions have also been demonstrated successfully in the fabrication of assembled structures, [23,24] responsive vesicles [23] and anion sensing systems. [22,28] Seeking for anion receptors which would also serve as the potential building units for the construction of artificial anion channels,wehave recently devised coronarenes, [29][30][31][32][33][34] anew type of macrocyclic compounds.C onstituted by para-(het)arylenes and heteroatoms in an alternative manner, coronarenes adopt coronary conformation with cylindroid cavities.F or example,O 6corona [3]arene [3]tetrazine 2 ( Figure 1) gives ar egular hexagonal structure with three tetrazine rings and six oxygen atom linkages form almost aplane while the three phenylene Figure 1. General structure of tetraoxacalix [2]arene [2]triazine 1,O 6corona [3]arene [3]tetrazine 2 and i-corona [3]arene [3] rings are nearly perpendicular to the plane.A sa ne lectrondeficient macrocycle,O 6 -corona [3]arene [3]tetrazinec omplexes with chlorides via anion-p interactions.…”

Electroactive Anion Receptor with High Affinity for Arsenate

“…1 H NMR (500 MHz, CDCl 3 ) δ 13.40 (s, 2H), 4.23 (q, J = 7.1 Hz, 4H), 2.42 (s, 6H), 1.30 (t, J = 7.1 Hz, 6H). 13 Diethyl 3,5-dimethyl-1,4-dithiine-2,6-dicarboxylate (7) THF (50 mL) was added to round bottom flask containing sodium hydride (3.31 g, 60% dispersion in mineral oil, 82.8 mmol, 3.0 equiv.). The mixture was cooled to 0 °C, and compound 5 (8.0 g, 27.6 mmol, 1.0 equiv.)…”