Peptide Nucleic Acids Containing Cationic/Amino-Alkyl Modified Bases Promote Enhanced Hybridization Kinetics and Thermodynamics with Single-Strand DNA.

Peptide nucleic acids (PNAs) are antisense molecules with excellent polynucleotide hybridization properties; they are resistant to nuclease degradation but often have poor cell permeability leading to moderate cellular activity and limited clinical results. The addition of cationic substitutions (positive charges) to PNA molecules greatly increases cell permeability. In this report, we describe the synthesis and polynucleotide hybridization properties of a novel cationic/amino-alkyl nucleotide base-modified PNA (OPNA).

Conformationally Locked Tolans, β-Sheet Structures, and Photophysical Properties.

Conformationally locked tetrasubstituted tolans were synthesized by introducing a tether on the tolan. To demonstrate the utilities of these motifs, a β-hairpin structure (15) was synthesized, and its additional stabilizing effects were evaluated. Moreover, the photophysical properties of cyclic tolans and their β-sheet structure were investigated.

A calix[2]phenol[2]pyrrole and a fused pyrrolidine-containing derivative.

The hybrid calix[2]phenol[2]pyrrole 4 and the fused pyrrolidine-containing macrocycle 9 were synthesized from two different isomeric starting materials, namely dimethyl 2-hydroxyisophthalate and 5-hydroxyisophthalate, respectively. The fused species 9 is devoid of obvious substrate binding properties. In contrast, the heterocalix system 4 displays the fluoride-induced conformational changes characteristic of the parent system.