Lee H, Tessarolo J, Langbehn D, Baksi A, Herges R, Clever GH. Light-Powered Dissipative Assembly of Diazocine Coordination Cages.
J Am Chem Soc 2022;
144:3099-3105. [PMID:
35081312 PMCID:
PMC8874908 DOI:
10.1021/jacs.1c12011]
[Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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Stimuli-responsive
coordination cages allow reversible control
over guest binding and release, relevant for adaptive receptors, carriers,
catalysts, and complex systems. Light serves as an advantageous stimulus,
as it can be applied with precise spatial and temporal resolution
without producing chemical waste products. We report the first Pd-mediated
coordination cage based on ligands embedding a diazocine photoswitch.
While the thermodynamically more stable cis-photoisomer
sloppily assembles to a mixture of species with general formula [Pdncis-L2n], the less stable trans-isomer yields a defined [Pd2trans-L4] cage that reversibly converts
back to the cis-system by irradiation at 530 nm or
thermal relaxation. The [Pdncis-L2n]
species do not bind a given guest; however, [Pd2trans-L4] is able to
encapsulate a bis-sulfonate as long as it is kept assembled, requiring
continuous irradiation at 385 nm. In the absence of UV light, thermal
relaxation results in back-switching and guest release. Assembly and
properties of the system were characterized by a combination of NMR,
ion mobility ESI-MS, single-crystal X-ray diffraction, and UV–vis
absorption studies.
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