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Publication Abstract from PubMed

Due to their unique coordination structure, dirhodium paddlewheel complexes are of interest in several research fields, like medicinal chemistry, catalysis, etc. Previously, these complexes were conjugated to proteins and peptides for developing artificial metalloenzymes as homogeneous catalysts. Fixation of dirhodium complexes into protein crystals is interesting to develop heterogeneous catalysts. Porous solvent channels present in protein crystals can benefit the activity by increasing the probability of substrate collisions at the catalytic Rh binding sites. Toward this goal, the present work describes the use of bovine pancreatic ribonuclease (RNase A) crystals with a pore size of 4 nm (P3(2)21 space group) for fixing [Rh(2)(OAc)(4)] and developing a heterogeneous catalyst to perform reactions in an aqueous medium. The structure of the [Rh(2)(OAc)(4)]/RNase A adduct was investigated by X-ray crystallography: the metal complex structure remains unperturbed upon protein binding. Using a number of crystal structures, metal complex accumulation over time, within the RNase A crystals, and structures at variable temperatures were evaluated. We also report the large-scale preparation of microcrystals ( approximately 10-20 mum) of the [Rh(2)(OAc)(4)]/RNase A adduct and cross-linking reaction with glutaraldehyde. The catalytic olefin cyclopropanation reaction and self-coupling of diazo compounds by these cross-linked [Rh(2)(OAc)(4)]/RNase A crystals were demonstrated. The results of this work reveal that these systems can be used as heterogeneous catalysts to promote reactions in aqueous solution. Overall, our findings demonstrate that the dirhodium paddlewheel complexes can be fixed in porous biomolecule crystals, like those of RNase A, to prepare biohybrid materials for catalytic applications.

Cross-Linked Crystals of Dirhodium Tetraacetate/RNase A Adduct Can Be Used as Heterogeneous Catalysts.,Loreto D, Maity B, Morita T, Nakamura H, Merlino A, Ueno T Inorg Chem. 2023 May 15;62(19):7515-7524. doi: 10.1021/acs.inorgchem.3c00852. , Epub 2023 May 5. PMID:37144589^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.