Coordination-driven self-assembly of truncated tetrahedra capable of encapsulating 1,3,5-triphenylbenzene

Abstract

The design and synthesis of coordinative truncated tetrahedra is described. The coordination-driven self-assembly of a truncated tetrahedron was achieved using 90° organoplatinum acceptors and a hexapyridyl ligand with six-fold symmetry under mild conditions. This tetrahedron can act as a host toward 1,3,5-triphenylbenzene. The truncated tetrahedral structures and the host-guest complex were identified using multinuclear ((31)P and (1)H) NMR spectroscopy, electrospray ionization mass spectrometry, X-ray crystallography, and pulsed-field-gradient spin-echo NMR, along with computational simulations.

Figure 1

³¹P{¹H} NMR spectra (121.4 MHz) of truncated tetrahedra 3a in acetone-d₆/CD₃NO₂ (a) and 3b in acetone-d₆/D₂O (b).

Figure 2

Crystal structure of truncated tetrahedron 3a (Pt: green; C: grey; N: blue; P: Orange; protons, solvent, and PF₆⁻ omitted for clarity).

Figure 3

Partial ¹H NMR spectra (300 MHz) of “free” 4 in acetone-d₆ (a), 3b in acetone-d₆/D₂O (b), and the encapsulated complex 3b·4₃ in acetone-d₆/D₂O (c).

Figure 4

Computational model (MMFF) of the encapsulated complex 3b·4₃ (For clarity, the three guest molecules are labeled as blue, green, and orange).

Scheme 1

Graphical representation of the [12 + 4] self-assembly of 90° organoplatinum acceptors 1 and hexapyridyl ligand 2 into a truncated tetrahedron 3.