Anion-Assisted Formation of Discrete Homodimeric and Heterotetrameric Assemblies by Benzene Based Protonated Heteroaryl Receptors

Anion-assisted formation of discrete homodimeric and heterotetrameric assemblies by benzene based protonated heteroaryl receptors <b>L</b>^<b>1</b>–<b>L</b>^<b>6</b> have been studied thoroughly by single crystal X-ray diffraction studies. Crystallographic results elucidate the fact that protonated tripodal receptor <b>L</b>^<b>1</b> formed staggered homodimeric capsular assemblies <b>2</b> and <b>3</b> with CF₃COO^– and ClO₄^– ions, respectively. Protonation of <b>L</b>^<b>3</b> with trimesic acid also showed the formation homodimeric assembly, <b>6</b>. In all these cases the anions are hydrogen bonded to the receptor molecules and show remarkable influence on the outcome of the self-assembly process to form discrete capsules. The necessity of the alkyl substitution on the benzene platform has been established from complexes <b>8</b>, <b>9</b>, and <b>10</b>, which were obtained upon protonation of <b>L</b>^<b>6</b> with HNO₃, HI, and HClO₄, respectively. Interestingly, when a 1:1 mixture of <b>L</b>^<b>1</b> (tripodal) and <b>L</b>^<b>5</b> (dipodal) were treated with HClO₄ and HBF₄, discrete heterotetrameric assemblies have been isolated as complexes <b>11</b> and <b>12</b>. The detailed solid state structural analysis of these complexes revealed the formation of heterotetrameric assemblies assisted by anion–water clusters. Correlation of these solid state structural assemblies with our previously reported complexes <b>1</b>, <b>4</b>, <b>5</b>, and <b>7</b> has also been described. The role of anionic templates in assisting the formation of discrete capsular assemblies from receptors possessing heteroaryl units and 1,3,5-methyl substituted benzene platform has been established

Anion-Assisted Formation of Discrete Homodimeric and Heterotetrameric Assemblies by Benzene Based Protonated Heteroaryl Receptors

Anion-assisted formation of discrete homodimeric and heterotetrameric assemblies by benzene based protonated heteroaryl receptors <b>L</b>^<b>1</b>–<b>L</b>^<b>6</b> have been studied thoroughly by single crystal X-ray diffraction studies. Crystallographic results elucidate the fact that protonated tripodal receptor <b>L</b>^<b>1</b> formed staggered homodimeric capsular assemblies <b>2</b> and <b>3</b> with CF₃COO^– and ClO₄^– ions, respectively. Protonation of <b>L</b>^<b>3</b> with trimesic acid also showed the formation homodimeric assembly, <b>6</b>. In all these cases the anions are hydrogen bonded to the receptor molecules and show remarkable influence on the outcome of the self-assembly process to form discrete capsules. The necessity of the alkyl substitution on the benzene platform has been established from complexes <b>8</b>, <b>9</b>, and <b>10</b>, which were obtained upon protonation of <b>L</b>^<b>6</b> with HNO₃, HI, and HClO₄, respectively. Interestingly, when a 1:1 mixture of <b>L</b>^<b>1</b> (tripodal) and <b>L</b>^<b>5</b> (dipodal) were treated with HClO₄ and HBF₄, discrete heterotetrameric assemblies have been isolated as complexes <b>11</b> and <b>12</b>. The detailed solid state structural analysis of these complexes revealed the formation of heterotetrameric assemblies assisted by anion–water clusters. Correlation of these solid state structural assemblies with our previously reported complexes <b>1</b>, <b>4</b>, <b>5</b>, and <b>7</b> has also been described. The role of anionic templates in assisting the formation of discrete capsular assemblies from receptors possessing heteroaryl units and 1,3,5-methyl substituted benzene platform has been established

Binding Studies on an Arene-Capped Bicyclic Cyclophane with π‑Rich Neutral Guests and Anions

Structural aspects of binding of π-rich neutral guests with <b>L</b> and anions with [H₆<b>L</b>]⁶⁺ are examined thoroughly. <b>L</b> forms inclusion complexes with π-rich solvents, 2DMSO⊂<b>L</b> (<b>1</b>), 3DMF⊂<b>L</b>₂ (<b>2</b>), (DMF·benzene·DMF)⊂<b>L</b>₂ (<b>3</b>), MeCN⊂<b>L</b> (<b>4</b>), and MeCOMe⊂<b>L</b> (<b>5</b>) in dimethylsulfoxide (DMSO), dimethyl formamide (DMF), benzene/DMF, acetonitrile (MeCN), and acetone (MeCOMe) respectively. The single crystal X-ray structural analysis of complexes illustrates cavity and cleft binding of these guests via N–H···O interactions in <b>1</b>, <b>2</b>, <b>3</b>, <b>5</b> and N–H···N interactions in <b>4</b> with the secondary nitrogen center of <b>L</b> and the hydrogen bonding acceptor atoms of the solvent guests. Inclusion of benzene in the side pocket is also observed in <b>3</b>. Our efforts to isolate single crystals with solvents such as MeOH, EtOH, CHCl₃, and CH₂Cl₂ are unsuccessful. Single crystal X-ray diffraction study has also shown the encapsulation of nitrate in the cleft of [H₆<b>L</b>]⁶⁺ via N–H···O hydrogen bonding interactions in [H₆<b>L</b>]­[NO₃]₆·HNO₃·6H₂O (<b>6</b>), whereas in [H₆<b>L</b>]₂[ClO₄]₁₂·CH₃OH·17H₂O (<b>7</b>) perchlorates are recognized in the cavity and side pockets of [H₆<b>L</b>]⁶⁺. This receptor has previously shown encapsulation of iodide (<b>8</b>), and Cl^–···H₂O (<b>9</b>). A potentiometric study of <b>L</b> exhibits the maximum concentration of [H₆<b>L</b>]⁶⁺ species at pH 2–3 in MeOH/H₂O 1:1 (v/v) binary solvent. Anion binding studies with <b>L</b> at pH 2.0 in MeOH/H₂O 1:1 (v/v) solvent system are examined by isothermal titration calorimetric (ITC) experiments

LabeoninicombinedExpandedDataset

LabeoniniCombinedExpandedDataset (for Fig. 1