1. Host-guest complexes of cucurbit[8]uril and [(η5-C5H4R)Mo(CO)3CH3] (R = H, CO2CH3) for controlled release of carbon monoxide.
- Author
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Gomes, Ana C., Monteiro, Rodrigo P., Calhau, Isabel B., Lopes, André D., Gonçalves, Isabel S., and Pillinger, Martyn
- Subjects
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X-ray powder diffraction , *METAL carbonyls , *METAL inclusions , *CARBON monoxide , *INCLUSION compounds , *CUCURBITURIL - Abstract
• New CO delivery systems based on the inclusion of metal carbonyls in cucurbit[8]uril. • Myoglobin CO-release assays performed for free/encapsulated [(η5-C5H4R)Mo(CO)3CH3]. • A wide range of rates for spontaneous CO-release was observed in aqueous systems. • CO release is attenuated by both introduction of r = CO2Me and by CB8 encapsulation. • UV irradiation promotes CO release from free/encapsulated [(η5-C5H4CO2Me)Mo(CO)3CH3]. The monosubstituted cyclopentadienyl half-sandwich molybdenum(II) tricarbonyl complex [(η 5-C 5 H 4 CO 2 CH 3)Mo(CO) 3 CH 3 ] (1) and its 1:1 inclusion compound with cucurbit[8]uril (1 @CB8) have been prepared and characterised by elemental and thermogravimetric analyses, powder X-ray diffraction, diffuse reflectance UV–vis, solid-state 13C{1H} MAS NMR, FT-IR, and Raman spectroscopies. The CO-releasing behaviours of 1, 1 @CB8 and, for comparison, [(η 5-C 5 H 5)Mo(CO) 3 CH 3 ] (2) and its 1:1 inclusion complex with CB8, were assessed using a deoxymyoglobin-carbonmonoxymyglobin assay. For assays performed in the dark at 37 °C, complex 1 undergoes thermally assisted spontaneous CO release, with ca. 0.5 equivalents of CO being released after 6 h. The half-life (t 1/2) of 325 min identifies 1 as a slow releaser when compared to complex 2 bearing the unsubstituted cyclopentadienyl ligand (t 1/2 = 25 min). CO release from 1 was promoted by exposure to UV light (t 1/2 = 85 min), establishing the complex as a photochemically activated CO-releasing molecule (photoCORM). For 1 @CB8, t 1/2 for photo-assisted CO release increased to ca. 7 h, and for 2 @CB8 the dark-release t 1/2 increased to 165 min, showing that molecular acceptors like cucurbiturils can be used effectively as second-sphere ligands to modulate the CO release profile of CORMs. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2024
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