Advanced materials for carbon dioxide removal from post-combustion streams: sustainable synergistic membranes

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Cyclopentadienyl vs indenyl control of thermal/photoactivated CO release in cationic molybdenum(II) dicarbonyl-ethylenediamine complexes

Publication . Bruno, Sofia M.; Calhau, Isabel B.; Dias, Tiago M.; Santos, Adriana; Silva, Luis Cunha; Nolasco, Mariela M.; Goncalves, Isabel S.; Pillinger, Martyn

ABSTRACT: Molybdenum half-sandwich carbonyl complexes continue to attract attention as potential anticancer agents and prodrugs for therapeutic use of carbon monoxide. Building on the known bioactivity and hydrolytic stability of cyclopentadienyl-based Mo fragments, we report the synthesis, structural characterization, and solution behavior of two cationic half-sandwich complexes, [(eta 5-Cp)Mo(CO)2(en)][BF4] (3) and [(eta 5-Ind)Mo(CO)2(en)][BF4] (4) (Cp = cyclopentadienyl, Ind = indenyl, en = ethylenediamine). Complex 3 is described here for the first time, while 4 was structurally characterized by single-crystal X-ray diffraction, revealing a distorted square-pyramidal geometry with cis-CO ligands and a chelating en ligand positioned beneath the indenyl ring. Both compounds are air-stable in the solid state and exhibit enhanced solubility in polar media due to their ionic nature. UV-vis stability studies under simulated physiological conditions (PBS, pH 7.4, 37 degrees C) show gradual decomposition of both complexes, accelerated by visible-light irradiation and/or the presence of air. CO-release behavior was quantified using the myoglobin assay: the allyl precursors [(eta 5-Cp')Mo(eta 3-C3H5)(CO)2] were inert, whereas complexes 3 and 4 released CO slowly, with 4 exhibiting significantly faster thermal CO liberation (t1/2 approximate to 129 min; 0.74 equiv. CO after 6 h). Complex 3 showed minimal thermal CO release but underwent enhanced and sustained photodecarbonylation under visible-light irradiation, enabling controlled CO delivery. These results identify 3 and 4 as rare examples of Mo-based CO-releasing molecules capable of slow, tunable CO release under biologically relevant conditions, with 3 displaying light-responsive behavior and 4 functioning as a spontaneous thermal CO donor.

2026-07Artigo científico

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Palavras-chave

1. CO2 separation / capture,2. Mixed Matrix Membranes (MMMs),3. Metal Organic Framework (MOF) materials,4. Deep Eutectic Solvents, Engineering and technology

Entidade financiadora

Fundação para a Ciência e a Tecnologia, I.P.

Programa de financiamento

Concurso para Projetos de Investigação de caráter Exploratório em Todos os Domínios Científicos 2024

Número da atribuição

2024.17214.PEX