The molecular structure of the spontaneously assembled supramolecular cluster [M4L6] n− has been explored with different metals (M = GaIII, FeIII, TiIV) and different encapsulated guests (NEt4 +, BnNMe3 +, Cp2Co+, Cp*2Co+) by X-ray crystallography. While the identity of the metal ions at the vertices of the M4L6 structure is found to have little effect on the assembly structure, encapsulated guests significantly distort the size and shape of the interior cavity of the assembly. Cations on the exterior of the assembly are found to interact with the assembly through either π−π, cation−π, or CH−π interactions. In some cases, the exterior guests interact with only one assembly, but cations with the ability to form multiple π−π interactions are able to interact with adjacent assemblies in the crystal lattice. The solvent accessible cavity of the assembly is modeled using the rolling probe method and found to range from 253−434 Å3, depending on the encapsulated guest. On the basis of the volume of the guest and the volume of the cavity, the packing coefficient for each host−guest complex is found to range from 0.47−0.67.

A series of bis(3-hydroxy-N-methyl-pyridin-2-one) ligands was synthesized and their respective uranyl complexes were characterized by single crystal X-ray diffraction analyses. These structures were inspected for high-energy conformations and evaluated using a series of metrics to

A new tridentate redox-active ligand platform, derived from bis(2-mercapto-p-tolyl)amine, [SNS(cat)]H(3), has been prepared in high yields by a four-step procedure starting from commericially available bis(p-tolyl)amine. The redox-active pincer-type ligand has been coordinated to tungsten to afford the six-coordinate, homoleptic complex W[SNS](2). To benchmark the redox behavior of the [SNS] ligand, the analogous tungsten complex of the well-known redox-active bis(3,5-di-tert-butylphenolato)amide ligand, W[ONO](2), also has been prepared. Both complexes show two reversible reductions and two partially reversible oxidations. Structural, spectroscopic, and electrochemical data all indicate that W[ONO](2) is best described as a tungsten(VI) metal center coordinated to two [ONO(cat)](3-) ligands. In contrast, experimental data suggests a higher degree of S→W π donation, giving the W[SNS](2) complex non-innocent electronic character that can be described as a tungsten(IV) metal center coordinated to two [SNS(sq)](2-) ligands.

The supramolecular host assembly [Ga(4)L(6)](12-) (1; L = 1,5-bis[2,3-dihydroxybenzamido]naphthalene) encapsulates cationic guest molecules within its hydrophobic cavity and catalyzes a variety of chemical transformations within its confined interior space. Despite the well-defined structure, the host ligand framework and interior cavity are very flexible and 1 can accommodate a wide range of guest shapes and sizes. These observations raise questions about the steric effects of confinement within 1 and how encapsulation fundamentally changes the motions of guest molecules. Here we examine the motional dynamics (guest bond rotation and tumbling) of encapsulated guest molecules to probe the steric consequences of encapsulation within host 1. Encapsulation is found to increase the Ph-CH(2) bond rotational barrier for ortho-substituted benzyl phosphonium guest molecules by 3 to 6 kcal/mol, and the barrier is found to depend on both guest size and shape. The tumbling dynamics of guests encapsulated in 1 were also investigated, and here it was found that longer, more prolate-shaped guest molecules tumble more slowly in the host cavity than larger but more spherical guest molecules. The prolate guests reduce the host symmetry from T to C(1) in solution at low temperatures, and the distortion of the host framework that is in part responsible for this symmetry reduction is observed directly in the solid state. Analysis of guest motional dynamics is a powerful method for interrogating host structure and fundamental host-guest interactions.