A series of geometrically well-defined cationic fluorophores were designed based on molecular mechanics. They contain biaryl linkers to impart rigidity preventing intramolecular folding between a conjugated biomolecule and fluorophore. All probes have absorption and emission maxima within 20 nm from Texas Red, as predicted by TDDFT calculations and validated experimentally.
Keywords: ion channel; molecular ruler; pore dilation; rhodamine.