resumo
The monosubstituted cyclopentadienyl half-sandwich molybdenum(II) tricarbonyl complex [(eta 5-C5H4CO2CH3) Mo(CO)3CH3] (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, [(eta 5-C5H5)Mo(CO)3CH3] (2) and its 1:1 inclusion complex with CB8, were assessed using a deoxymyoglobin-carbonmonoxymyglobin assay. For assays performed in the dark at 37 degrees C, complex 1 undergoes thermally assisted spontaneous CO release, with ca. 0.5 equivalents of CO being released after 6 h. The half-life (t1/2) of 325 min identifies 1 as a slow releaser when compared to complex 2 bearing the unsubstituted cyclopentadienyl ligand (t1/2 = 25 min). CO release from 1 was promoted by exposure to UV light (t1/2 = 85 min), establishing the complex as a photochemically activated CO-releasing molecule (photoCORM). For 1@CB8, t1/2 for photo-assisted CO release increased to ca. 7 h, and for 2@CB8 the dark-release t1/2 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.
palavras-chave
INFRARED SPECTROSCOPIC EVIDENCE; MOLECULES CO-RMS; METAL-COMPLEXES; PHOTOCHEMISTRY; MOLYBDENUM; TOXICITY; INJURY; DEGRADATION; PHOTOLYSIS; STABILITY
categoria
Chemistry
autores
Gomes, AC; Monteiro, RP; Calhau, IB; Lopes, AD; Gonçalves, IS; Pillinger, M
nossos autores
Ana Catarina Costa Gomes Alves
Investigador Auxiliar
Isabel Maria de Sousa Gonçalves
Professor associado
Martyn Pillinger
Investigador Principal
Rodrigo Pinto Monteiro
Estudante de doutoramentoProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials (UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020) , UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) and LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020) ) , financed by national funds through the FCT (Fundacao para a Ciencia e a Tecnologia) /MCTES (Ministerio da Ciencia, Tecnologia e Ensino Superior) (PIDDAC) . R.P.M. (DOI 10.54499/2020.04758.BD) and I.B.C. (DOI 10.54499/2021.05953.BD) are grateful to the FCT and the European Social Fund for a PhD grants. A.C.G. acknowledges the FCT/MCTES for an Assistant Researcher Position funded through the Individual Call to Scientific Employment Stimulus (ref. CEECIND/02128/2017; DOI 10.54499/CEECIND/02128/2017/CP1459/CT0039) . The NMR spectrometers used in this work are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project N degrees 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL, and FCT through PIDDAC) .