Stimuli-Responsive Polydiacetylene Based on the Self-Assembly of a Mercury-Bridged Macrocyclic Diacetylene Dimer

The metal-mediated self-assembly process allows the well-directed and controlled construction of supramolecular archi-tectures, and the assembled metal-ligand complexes display diverse functionalities depending on the composition of the complextemplate. Through the deliberate introduction of a metal-bindingnucleobase, cytosine, to the macrocyclic diacetylene (MCDA), amacrocyclic ligand,CytMCDA, was synthesized. On account of themetal affinity of cytosine and the pi-pi interaction of the diacetylenetemplate, a Hg-coordinated unidirectional columnar self-assembly ofCytMCDAwas generated that formed into organic nanotubes. ThemonomericCytMCDA-Hgis covalently cross-linked to the blue-phase macrocyclic polydiacetylene nanotubes (CytMCPDA-Hg)via UV-induced topochemical polymerization.CytMCPDA-Hgdisplayed a naked-eye-detectable sensing response toward heat andsolvents with a brilliant blue-red chromatic transition. Moreover, owing to the high affinity of the mercury complex toward sulfur, CytMCPDA-Hg displayed a high sensitivity against thiols.