Transformations in Chemically Responsive Copper‐Calixarene Architectures

• Published in: Chemistry, an Asian journal Vol. 13; no. 5; pp. 520 - 527
• Main Authors: Percástegui, Edmundo G., Reyes‐Mata, Carlos, Flores‐Alamo, Marcos, Quiroz‐García, Beatriz, Rivera, Ernesto, Castillo, Ivan
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 02-03-2018
• Subjects: Assembly; Cages; Calixarenes; Chemistry; Copper; copper complexes; Oxidation; Robustness (mathematics); self-assembly; stimuli-responsiveness; supramolecular chemistry; Thermochromism; Stimuli-responsiveness; self-assembly; supramolecular chemistry
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201701741

Self‐assembly of bis‐picolyl‐appended calix[4]arene (L) with CuI or CuII salts resulted in a collection of multinuclear architectures capable of expressing structural reconfigurations in response to various chemical stimuli: addition of copper salt, solvents, or oxidation. Coordination of L to CuX (X=Br, I) selectively yielded dinuclear macrocycles CuI2L2Br2 (1) and CuI2L2I2 (3) that were transformed into tetranuclear assemblies CuI4L2Br4 (2) and CuI4L2I4 (4) upon further addition of CuX. These supramolecules persist as robust and discrete entities in solution that display red emission; notably, 4 exhibits luminescence thermochromism. Assembly of L with CuCl2 produced macrocycle CuII2L2Cl4 (5), which crystallised as cage [CuII2L4(μ‐Cl)]3+ (6) in the presence of MeOH. Two chemical signals—introduction of CuCl2 and addition of CH3CN—regenerated macrocycle 5. Coordination of L to Cu(OTf) yielded macrocycle CuI2L2(OTf)2 (7) that also crystallised as cage 6 upon oxidation in CHCl3.
Change is good: Self‐assembled copper‐calix[4]arene architectures express structural transformations and varied emissive features upon receipt of diverse chemical stimuli such as further addition of copper halide, solvents, or oxidation.