High affinity threading of a new tetralactam macrocycle in water by fluorescent deep-red and near-infrared squaraine dyes.

A new tetralactam macrocycle was prepared and found to encapsulate deep-red and near-infrared squaraine and croconaine dyes in water with tunable threading kinetics. The new supramolecular paradigm of guest back-folding was used to increase macrocycle/squaraine affinity by 370-fold and achieve an association constant of 2.8 × 109 M-1.