Cu^II‐Templated Threading of a Bis‐amide‐tris‐amine Macrocycle by Substituted 2,2′‐Bipyridyl Derivatives Assisted by Strong π–π Stacking and Second‐Sphere H‐Bonding Interactions

Abstract

Derivatives of 5,5Ј-substituted 2,2Ј-bipyridine (BPy) ligands with bromo-terminated aliphatic side chains with ester functionalities (BPy5Br), hydroxy-terminated aliphatic side chains with amide functionalities (BPy5OH), and benzyl-terminated side chains with amide functionalities (BPy5Bnz) were synthesized. The single-crystal X-ray structure analysis of the axle BPy5Br shows that it has a linear rodlike structure with a length of 15.75 Å. The above three ligands along with a methyl-substituted BPy ligand (BPy5Me) are explored as axles for Cu II -templated threading of a bis-amide-tris-amine macrocycle wheel (MC). High-yield (70-80 %) syntheses of the [2]pseudorotaxanes PRT1, PRT2, PRT3, and PRT4 are obtained by reaction of MC with the axles BPy5Me, BPy5Br, BPy5OH, and BPy5Bnz, respectively, in the presence of Cu II ions. These complexes were characterized by ESI-MS, UV/ Vis and EPR spectroscopy, and single-crystal X-ray diffraction studies. The solution-state binding stoichiometry and the association constants for complex formation between MC- [a]Cu 2+ and the axles were studied by UV/Vis absorption titrations. Sigma-fit curves indicate 1:1 stoichiometry, and the association constants range from 1.2 ϫ 10 3 to 2.6 ϫ 10 3 M -1 . Single-crystal X-ray structure analysis of PRT1, PRT2, and PRT4 confirms the threading of MC by the respective axles, which are coordinated to the Cu II center with Cu-N bond lengths of 1.992-2.203 Å. Interestingly, strong aromatic π-π stacking interactions between two parallel arene moieties of MC and the pyridyl unit of the axle with π-π interaction distances of 3.402-3.618 Å are observed in all three [2]pseudorotaxanes. However, for PRT4, a strong hydrogen-bonding interaction is also operative between the carbonyl oxygen atom of BPy5Bnz and the amide proton of MC with a N-H···O distance of 2.200 Å. Thus, multiple template interactions such as metal coordination, π-π stacking, and second-sphere hydrogen-bonding interactions between MC and the axles play crucial roles for facile threading and high-yield syntheses of [2]pseudorotaxanes.

Treatment of Oil-Contaminated Soil from Kuwaiti Dry Oil Lakes: Development of a New Processing Technology

“…As described in section , L-COOH-Cl included the terpyridine complexes moiety and carboxylic acid groups, which would be expected to have a good performance for coordinating with N, S, and metal complexes. , Therefore, it was inferred that asphaltenes were mainly separated from the surface of soil particles by coordinating with heteroatoms in asphaltenes. To determine the mechanism of asphaltenes removal, XPS analysis was conducted.…”

From construction to application of a new generation of interlocked molecules composed of heteroditopic wheels

“…2). 15 b ,25 Moreover, our group has also demonstrated macrobicyclic, W11 and pyridine N -oxide axle-based HB templated [2]pseudorotaxane ( P4 ) formation where the changes of the pyridine N -oxide axle direction within the wheel were studied. 20 Recently Yuan and co-workers constructed a different type of [2]pseudorotaxane ( P5 ) by incorporating a heteroditopic cyclo[6]aramide wheel that shows binding of dibutyl ammonium chloride via HB interactions.…”

Copper(ii)-directed synthesis of neutral heteroditopic [2]rotaxane ion-pair host systems incorporating hydrogen and halogen bonding anion binding cavities

“…Recently Ghosh and co-workers have demonstrated copper(II)-templated pseudorotaxane assembly between a tris-aminefunctionalised macrocycle and a range of bipyridine, phenanthroline and 2-pyridyl-benzimidazole threading compounds. 19,24,25,[27][28][29] Similarly, evidence for the formation of copper(II)-templated pseudorotaxane assemblies between the new isophthalamide-containing copper-complexed macrocycle 3•Cu(ClO 4 ) 2 and 2,2-bipyridyl and 4-iodopyridyl-2,6-dicarbonyl threading ligands was obtained using UV-visible spectroscopy and X-ray crystallography techniques. For the purposes of the pseudorotaxane assembly investigations unsubstituted 2,2bipyridine was used as a model threading ligand in place of a 4,4-bis-amide functionalised analogue owing to the prohibitively low solubilities of simple 4,4-bis-amide functionalised 2,2-bipyridine derivatives (Scheme 2).…”