Thinking Outside the “Blue Box”: Induced Fit within a Unique Self-Assembled Polycationic Cyclophane

• DOI: 10.1021/jacs.8b12599
• Publication Date: 2019-02-07T22:55:55Z
• Authors: Arturo Blanco-Gómez; Ángel Fernández-B...; Víctor Blanco; Jaime Rodríguez; Carlos Peinador; Marcos D. García
• Keywords: Cyclophane

We present herein the development of a new polycationic molecular receptor, inspired by ubiquitous cyclobis(paraquat-p-phenylene)cyclophane ("blue box"). Our analogue, "white box", has been easily self-assembled on preparative scale in water, using template-assisted process acyl hydrazone bonding complementary bis(pyridinium)xylylene tweezers, followed kinetic trapping empty receptor. The obtained macrocycle was found to display marked pH responsiveness because an abnormal acidity amide protons within its structure. Consequently, and concurrence rotational isomerism under acidic conditions (fixed at higher values), compound dual behavior as conformationally locked/flexible host, being able recognize appropriate aromatic substrates, lock key or induced fit fashion, conjunction π–π, C–H···π, and, crucially, hydrophobic effect.