High Affinity Macrocycle Threading by a Near-Infrared Croconaine Dye with Flanking Polymer Chains

作者：Liu Wenqi; Peck Evan M; Smith Bradley D^*

来源：Journal of Physical Chemistry B, 2016, 120(5): 995-1001.

DOI：10.1021/acs.jpcb.5b11961

Croconaine dyes have narrow and intense absorption bands at similar to 800 mn, very weak fluorescence, and high photo stabilities, which combine to make them very attractive chromophores for absorption-based imaging or laser heating technologies. The physical supramolecular properties of croconaine dyes have rarely been investigated, especially in water. This study focuses on a molecular threading process that encapsulates a croconaine dye inside a tetralactam macrocyde in organic or aqueous solvent. Macrocycle association and rate constant data are reported for a series of croconaine structures with different substituents attached to the ends of the dye. The association constants were highest in water (K-a similar to 10(9) M-1), and the threading rate constants (k(on)) increased in the solvent order H2O > MeOH > CHCl3. Systematic variation of croconaine substituents located just outside the croconaine/macrocycle complexation interface hardly changed K-a but had a strong influence on k(on). A croconaine dye with N-propyl groups at each end of the structure exhibited a desirable mixture of macrocyde threading properties; that is, there was rapid and quantitative croconaine/macrocycle complexation at relatively high concentrations in water, and no dissociation of the preassembled complex when it was diluted into a solution of fetal bovine serum, even after laser induced photothermal heating of the solution. The combination of favorable near-infrared absorption properties and tunable mechanical stability makes threaded croconaine/macrocycle complexes very attractive as molecular probes or as supramolecular composites for various applications in absorption-based imaging or photothermal therapy.

• 出版日期2016-2-11