Synthesis and Self‐Association of Double‐Helical AADD Arrays

Abstract

The design and syntheses of four self-complementary oligomers that contain an underlying AADD hydrogen bond sequence are presented, and their self-association was examined in the solution and solid state. The molecular recognition between the two strands is highly sensitive to substitutions of their component heterocycles. Substitution with electron-donating and -withdrawing groups and the influence of preorganization has a large effect on the overall stabilities of the complexes studied. In particular, a wide range (>10(5) M(-1)) of stabilities with respect to substitutions at various positions in the AADD oligomers was demonstrated. In the most extreme case, the dimerization constant measured (K(dimer) ≥4.5×10(7) M(-1)) is comparable to the most stable homodimers of neutral AADD arrays reported to date.

Supramolecular Helical Systems: Helical Assemblies of Small Molecules, Foldamers, and Polymers with Chiral Amplification and Their Functions

“…447 Wisner and co-workers synthesized an alternate ADADA pentamer (270) and AADD tetramer (271) using a pyridine unit, and 1,4-thiazine-1,1-dioxide and indole units as a hydrogen acceptor (A) and donor (D), respectively (Figure 84B). 448,449 − and the two ligand strands (Figure 84C). 450 The single-crystal X-ray analysis of its model, [(272) 2 H 2 ](FeCl 4 ) 2 , supports such a doubly hydrogen-bonded double-helical structure.…”

“…(B) Chemical and X-ray crystal structures of 270 and 271 . (Reproduced with permission from refs and . Copyright 2007 American Chemical Society and Copyright 2012 Wiley-VCH, respectively.)…”

Self-complementary quadruple hydrogen bonding motifs: from design to function

“…8) which can undergo self assembly through AADD mode of H-bonding. 37 Fig. 6 Effect of ring size in the equilibrium of folded and unfolded conformation of heterocyclic ureas affecting the mode of self-assembly.…”

Folding and duplex formation in mixed sequence recognition-encodedm-phenylene ethynylene polymers

“…Progress has been made in the development of synthetic oligomers that fold into well-dened three-dimensional structures based on the sequence of building blocks, [7][8][9][10][11][12] or that form duplexes in a sequence-selective manner. [13][14][15][16][17][18][19][20] Some of these synthetic systems also exhibit properties that resemble those found in biopolymers, such as substrate binding, self-assembly and catalysis. [21][22][23][24][25][26][27] One of the most important functional properties found in biomolecules is the ability of nucleic acid oligomers to template the synthesis of a specic sequence of another oligomer, either protein or nucleic acid.…”