Exploring and Expanding the Structural Diversity of Self‐Assembling Dendrons through Combinations of AB, Constitutional Isomeric AB₂, and AB₃ Biphenyl‐4‐Methyl Ether Building Blocks

Abstract

General, efficient and inexpensive methods for the synthesis of dendritic building blocks methyl 3',4'-dihydroxybiphenyl-4-carboxylate, 3',5'-dihydroxybiphenyl-4-carboxylate, and methyl 3',4',5'-trihydroxybiphenyl-4-carboxylate were elaborated. In all syntheses the major step involved an inexpensive Ni(II)-catalyzed Suzuki cross-coupling reaction. These three building blocks were employed together with methyl 4'-hydroxybiphenyl-4-carboxylate in a convergent iterative strategy to synthesize seven libraries containing up to three generations of 3',4'-, 3',5'-, and 3',4',5'-substituted biphenyl-4-methyl ether based amphiphilic dendrons. These dendrons self-assemble into supramolecular dendrimers that self-organize into periodic assemblies. Structural and retrostructural analysis of their assemblies demonstrated that these dendrons self-assemble into hollow and non-hollow supramolecular dendrimers exhibiting dimensions of up to twice those reported for architecturally related dendrons based on benzyl ether repeat units. These new dendrons expand the structural diversity and demonstrate the generality of the concept of self-assembling dendrons based on amphiphilic arylmethyl ethers.

Why Are Biological Systems Homochiral?

“…8 Therefore, here we will first discuss the most important concepts elaborated since these reviews were published, and some very fundamental problems from before these reviews were published. Libraries of self‐assembling dendrons based on amphiphilic benzyl ether,9 phenylpropyl ether,10 biphenylmethyl ether,11 biphenylpropyl ether,12 and of dendrons with even more complex architectures were investigated 13. A combination of structural and retrostructural analysis methods based on x‐ray diffraction was elaborated to demonstrate that the two most frequently encountered supramolecular architectures assembled from all of them are columnar14 and spherical or globular 15.…”

Self-Assembly of Dendritic Dipeptides as a Model of Chiral Selection in Primitive Biological Systems

“…Since their initial discovery, several generational libraries of Percec-type dendrimers have been prepared including the benzyl [45] (Fig. 1), biphenylmethyl [46], propylphenyl [47], and propylbiphenyl [32] ether series, as well as related AB 4 /AB 5 [48], hybrid [49], and deconstructed topologies [50]. The most common mechanisms of selfassembly for Percec-type dendrons include the packing of cone-shaped dendrons or crowns [51,52] into spheres or polyhedral sphere-like objects [53] (Fig.…”

Deconstruction as a Strategy for the Design of Libraries of Self‐Assembling Dendrons

“…At elevated temperatures, compounds 12 a , b self‐organize into bicontinous Ia $\bar 3$ d cubic phases (Cub bi , Figure 6). The Cub bi phase has also been observed for phasmidic molecules10b and dendrons with semifluorinated periphery,11 but has not been found in generational libraries of self‐assembling dendrons3a–c, e or self‐assembling hybrid dendrons 3d. f The Cub bi phase generated from 12 a , b can be approximated by interconnected distorted columnar segments with a diameter of approximately 70 Å (Figure 6).…”

“…The current design of self‐assembling dendron libraries involves a generational strategy in which first generation dendrons are sequentially added to constitutional isomeric AB n ( n ≥ 2) building blocks to produce higher‐generation dendrons 2. 3a–d The synthesis, structural, and retrostructural analysis of generational libraries of self‐assembling dendrons,3a–c, e as well as of hybrid AB n ‐(AB) y dendrons,3d, f enabled the discovery of diverse self‐organizable supramolecular dendrimers 4. Despite differences in building‐block structure, homologous connective topologies of dendrons from different generational libraries provide a conserved and therefore predictable3e assembly of the supramolecular dendrimers that is programmed by their primary structure.…”

“…Unfortunately, the predictability reduces the likelihood of finding new supramolecular structures through the synthesis of additional generational libraries. The discovery of new supramolecular architectures from self‐assembling dendrons requires the synthesis of dendritic structures that were not previously accessible through the strategies of generational3a–c, e or hybrid dendron libraries 3d. f–g Aside from the generational and combined generational hybrid strategies, no other rational method to the design of libraries required to access dendrons with novel primary structures is available.…”