Pd^II and Pt^II Complexes with Amphiphilic Ligands: Formation of Micelles and [5]Rotaxanes with α‐Cyclodextrin in Aqueous Solution

Abstract

[3]Pseudorotaxanes [1(alpha-CD)(2)][X] (X=Cl, NO(3)), prepared from reaction of an N-alkylbipyridinium [4,4'-bpy-N-(CH(2))(10)OC(6)H(3)-3,5-(OMe)(2)][X] ([1][X]) and alpha-CD, react with M(NO(3))(2)(en) (M=Pd, Pt; en=1,2-ethylenediamine) in a 2:1 molar ratio to afford [5]rotaxanes [M{(4,4'-bpy-N-(CH(2))(10)OC(6)H(3)-3,5-(OMe)(2))(alpha-CD)(2)}(2) (en)][NO(3)](4) ([2(alpha-CD)(4)][NO(3)](4), M=Pd; [3(alpha-CD)(4)][NO(3)](4), M=Pt). A similar reaction of [1][Cl] with [M(NO(3))(2)(en)] (M=Pd, Pt) produces amphiphilic Pd and Pt complexes, [2][NO(3)](4) and [3][NO(3)](4). Complexes [2][NO(3)](4) and [3][NO(3)](4) form micelles in the presence of small amounts of dyes (Nile red and pyrene) in water. The critical micelle concentration (CMC) was determined by the absorption peak of the dye, which is encapsulated in the micelles in solution. Micelle formation is confirmed by dynamic light scattering measurement of the solution and TEM (transmission electron microscopy) images of the micelles deposited from the solution. Addition of alpha-CD to the aqueous solution containing these amphiphilic complexes results in degradation of the micelle structure and the formation of [5]rotaxanes, [2(alpha-CD)(4)][NO(3)](4) and [3(alpha-CD)(4)][NO(3)](4).

Strategies and Tactics for the Metal‐Directed Synthesis of Rotaxanes, Knots, Catenanes, and Higher Order Links

“…[232] A cyclodextrin-based [5]rotaxane has been reported by Osakada and co-workers, using Pd II or Pt II coordination to bridge two pseudo [3]rotaxanes. [233] Kim demonstrated the construction of 1D polyrotaxanes such as 172-Ag I , by employing Co II , [95] Ni II , [95] Cd II , [95] Cu II [95,200] or Ag I [95,[234][235][236] as "connectors" to form a linear network of pseudorotaxane cucurbituril-bispyridyl-bis(dialkylammonium) units, threaded by intercomponent hydrogen bonding (Scheme 63). Lui and co-workers [237] prepared related 1D-polyrotaxanes based on 4,4'-bipyridine and cyclodextrins linked by Ni II[237a] or Cu II ions [237b] or Ru II (bpy) 2 groups.…”

Metallosurfactants Consisting of Amphiphilic Ligands and Transition Metals: Structure, Bonding, Reactivity, and Self-assembling Property

“…2 19) . The authors synthesized a series of Pd-and Pt-containing MSs 20) . The reaction of 3 with M (NO 3…”

Exploring and Exploiting the Symmetry-Breaking Effect of Cyclodextrins in Mechanomolecules

“…There are a few examples of discrete [n>3]rotaxanes [56][57][58][59] based on CD templates, but the ring orientations are not well characterized. In 1992, Harada [60] reported the first synthesis of a CD polyrotaxane, comprising polyethylene glycol (PEG) threaded by many α-CD rings.…”