posted on 2021-06-04, 00:04authored byPavle Troselj, Peter Bolgar, Pablo Ballester, Christopher A. Hunter
Melamine oligomers
composed of repeating triazine-piperidine units
and equipped with phenol and phosphine oxide side-chains form H-bonded
duplexes. The melamine backbone provides sufficient rigidity to prevent
intramolecular folding of oligomers up to three recognition units
in length, leading to reliable duplex formation between sequence complementary
oligomers. NMR spectroscopy and isothermal titration calorimetry (ITC)
were used to characterize the self-assembly properties of the oligomers.
For length-complementary homo-oligomers, duplex formation in toluene
is characterized by an increase in stability of an order of magnitude
for every base-pair added to the chain. NMR spectra of dilute solutions
of the AD 2-mer show that intramolecular H-bonding between
neighboring recognition units on the chain (1,2-folding) does not
occur. NMR spectra of dilute solutions of both the AAD and the ADD 3-mer show that 1,3-folding does not take
place either. ITC was used to characterize interactions between all
pairwise combinations of the six different 3-mer sequences, and the
sequence complementary duplexes are approximately an order of magnitude
more stable than duplexes with a single base mismatch. High-fidelity
duplex formation combined with the synthetic accessibility of the
monomer building blocks makes these systems attractive targets for
further investigation.