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Supramolecular Structural Diversity among First‐Generation Hybrid Dendrimers and Twin Dendrons
Author(s) -
Percec Virgil,
Rudick Jonathan G.,
Peterca Mihai,
Yurchenko Michael E.,
Smidrkal Jan,
Heiney Paul A.
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701658
Subject(s) - dendrimer , supramolecular chemistry , materials science , crystallography , amine gas treating , phase transition , self assembly , lamellar structure , stereochemistry , chemistry , polymer chemistry , nanotechnology , crystal structure , physics , organic chemistry , quantum mechanics
Hybrid dendrimers, obtained by complete monofunctionalization of the peripheral amines of a “zero‐generation” polyethyleneimine dendrimer, provide structurally diverse lamellar, columnar, and cubic self‐organized lattices that are less readily available from other modified dendritic structures. The reaction of tris(2‐aminoethyl)amine (TREN) with 4‐dodecyloxybenzimidazolide provides only the corresponding zero‐generation TREN dendrimer. From the mixture of tri‐ and disubstituted TREN derivatives obtained from first‐generation self‐assembling dendritic imidazolides, the hybrid dendrimer and a twin dendron could be separated, purified, and characterized. The hybrid dendrimers display smectic, columnar hexagonal ( Φ h ), and cubic ( Pm $\bar 3$ n ) lattices. The TREN twin dendrons, on which only two peripheral amines have been acylated, exhibit centered‐rectangular columnar ( Φ r‐c ), Φ h , and Pm $\bar 3$ n lattices. The existence of a thermoreversible Φ h ‐to‐ Pm $\bar 3$ n phase transition in the first‐generation hybrid dendrimers and twin dendrons is exploited to elucidate an epitaxial relationship between the two mesophases. We postulate a mechanism by which the transition proceeds. The thermoreversible Φ h ‐to‐ Pm $\bar 3$ n phase change is accompanied by optical property changes that are suitable for rudimentary signaling or logic functions. This structural diversity reflects the quasiequivalence of flat‐taper and conical self‐assembling dendrons and the ability of flexible dendrimers to accommodate concomitant conformational and shape changes.