4 research outputs found
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><sup><b>1</b></sup>–<b>L</b><sup><b>6</b></sup> have been studied thoroughly by single crystal X-ray
diffraction studies. Crystallographic results elucidate the fact that
protonated tripodal receptor <b>L</b><sup><b>1</b></sup> formed staggered homodimeric capsular assemblies <b>2</b> and <b>3</b> with CF<sub>3</sub>COO<sup>–</sup> and ClO<sub>4</sub><sup>–</sup> ions, respectively. Protonation of <b>L</b><sup><b>3</b></sup> 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><sup><b>6</b></sup> with HNO<sub>3</sub>, HI, and HClO<sub>4</sub>, respectively. Interestingly, when a 1:1 mixture of <b>L</b><sup><b>1</b></sup> (tripodal) and <b>L</b><sup><b>5</b></sup> (dipodal) were treated with HClO<sub>4</sub> and HBF<sub>4</sub>, 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><sup><b>1</b></sup>–<b>L</b><sup><b>6</b></sup> have been studied thoroughly by single crystal X-ray
diffraction studies. Crystallographic results elucidate the fact that
protonated tripodal receptor <b>L</b><sup><b>1</b></sup> formed staggered homodimeric capsular assemblies <b>2</b> and <b>3</b> with CF<sub>3</sub>COO<sup>–</sup> and ClO<sub>4</sub><sup>–</sup> ions, respectively. Protonation of <b>L</b><sup><b>3</b></sup> 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><sup><b>6</b></sup> with HNO<sub>3</sub>, HI, and HClO<sub>4</sub>, respectively. Interestingly, when a 1:1 mixture of <b>L</b><sup><b>1</b></sup> (tripodal) and <b>L</b><sup><b>5</b></sup> (dipodal) were treated with HClO<sub>4</sub> and HBF<sub>4</sub>, 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
Ï€-rich neutral guests with <b>L</b> and anions with [H<sub>6</sub><b>L</b>]<sup>6+</sup> are examined thoroughly. <b>L</b> forms inclusion complexes
with π-rich solvents, 2DMSO⊂<b>L</b> (<b>1</b>), 3DMF⊂<b>L</b><sub>2</sub> (<b>2</b>), (DMF·benzene·DMF)⊂<b>L</b><sub>2</sub> (<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, CHCl<sub>3</sub>, and CH<sub>2</sub>Cl<sub>2</sub> are unsuccessful.
Single crystal X-ray diffraction study has also shown the encapsulation
of nitrate in the cleft of [H<sub>6</sub><b>L</b>]<sup>6+</sup> via N–H···O hydrogen bonding interactions
in [H<sub>6</sub><b>L</b>]Â[NO<sub>3</sub>]<sub>6</sub>·HNO<sub>3</sub>·6H<sub>2</sub>O (<b>6</b>), whereas in [H<sub>6</sub><b>L</b>]<sub>2</sub>[ClO<sub>4</sub>]<sub>12</sub>·CH<sub>3</sub>OH·17H<sub>2</sub>O (<b>7</b>) perchlorates are
recognized in the cavity and side pockets of [H<sub>6</sub><b>L</b>]<sup>6+</sup>. This receptor has previously shown encapsulation
of iodide (<b>8</b>), and Cl<sup>–</sup>···H<sub>2</sub>O (<b>9</b>). A potentiometric study of <b>L</b> exhibits the maximum concentration of [H<sub>6</sub><b>L</b>]<sup>6+</sup> species at pH 2–3 in MeOH/H<sub>2</sub>O 1:1
(v/v) binary solvent. Anion binding studies with <b>L</b> at
pH 2.0 in MeOH/H<sub>2</sub>O 1:1 (v/v) solvent system are examined
by isothermal titration calorimetric (ITC) experiments