Environment-Sensitive Probes Containing a 2,6-Diethynylpyridine Motif for Fluorescence Turn-On Detection and Induction of Nanoarchitectures of Human Telomeric Quadruplex

Bis(phenylethynyl) pyridylcarboxamides with amide side chains at the para position of the NH2 group possess strong solvatochromic properties compared with the meta analogues. Fluorescence binding titrations show that these probes exhibit remarkable fluorescence turn-on responses upon interacting with the human telomeric G-quadruplex (h-TELO). Forster resonance energy transfer melting analysis shows the high selectivity of these probes for h-TELO over duplex DNA. Isothermal titration calorimetry, as well as UV/Vis and fluorescence spectroscopy studies, show that the meta analogue has a twofold binding affinity for h-TELO over the para analogue. The noncovalent interaction of these small-molecule probes with h-TELO has been used to regulate the assembly of novel supramolecular nanoarchitectures.