Definitive Support by Transmission Electron Microscopy, Electron Diffraction, and Electron Density Maps for the Formation of a BCC Lattice from Poly{N-[3,4,5-tris(n-dodecan-l-yloxy)benzoyl]ethyleneimine}

Abstract

Transmission electron microscopy (TEM), electron diffraction (ED), and electron density maps (EDM) experiments were carried out on a poly[N-[3,4,5-tris(n-dodecan-1-yloxy)benzoyl]ethyleneimine] [poly[(3,4,5)12G1-Oxz]] with a degree of polymerization (DP) of 20. All experiments confirmed the thermotropic body-centered cubic (BCC) Im3m lattice suggested previously by X-ray diffraction (XRD) experiments. The unit cell parameter determined by ED at 23 degrees C is a = 42.4 A, in good agreement with XRD results which show a = 42.6 A after quenching from 70 degrees C. EDM of the XRD results confirm that the supramolecular minidendrimer obtained from poly[(3,4,5)12G1-Oxz] adopts a spherical "inverse micellar-like" structure, with the polyethyleneimine backbone and the aromatic groups microsegregated and concentrated in the corners and in the center of the cubic unit cell. A space-filling continuum is realized by the n-alkyl groups that radiate out of the aromatic core of the spherical dendrimer. This manuscript is only the second example of complete structural analysis of a lattice generated from supramolecular objects and complements the previous example reported from our laboratory on the Pm3n lattice.

Exploring and Expanding the Three-Dimensional Structural Diversity of Supramolecular Dendrimers with the Aid of Libraries of Alkali Metals of Their AB3 Minidendritic Carboxylates

“…Nevertheless we can provide at least a qualitative explanation for the formation of Im $\bar 3$ m versus Pm $\bar 3$ n or the combination of Pm $\bar 3$ n and Im $\bar 3$ m lattices for different metal salts and number of methylene units in the alkyl tail (Figure 1). As suggested in recent publications,2b, 14 the Im $\bar 3$ m lattice is generated from more perfect supramolecular spherical objects than the one that generates the Pm $\bar 3$ n lattice. In the cubic lattice the alkyl tails of the supramolecular dendrimer are conformationally disordered 9.…”

Self-assembling supramolecular systems of different symmetry formed by wedged macromolecular dendrons

“…If S ~ r 2 , the dendron has a con ical shape. These cones are most often formed by micelles, which are ordered into mesophases of differ ent symmetry [54,55]: cubic phases [56,57] and [58,59], as well as the tetragonal phase P4 2 /mnm [53]. Note that the dendron focal angle can also be changed by mixing two different mesogenic compounds [60].…”

In vivo selective inhibition of mitogen‐activated protein kinase kinase 1/2 in rabbit experimental osteoarthritis is associated with a reduction in the development of structural changes

“…Our laboratory is involved in the elaboration of libraries of monodisperse self‐assembling dendrons that produce supramolecular architectures of sufficient shape perfection to allow their self‐organization into unprecedented three‐dimensional (3D) and two‐dimensional (2D) lattices 1–30. A retrostructural analysis of the structure of these lattices that provides a rational approach to the design and synthesis of libraries of self‐assembling dendrons is outlined in Scheme .…”