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Ca K-edge XAS as a probe of calcium centers in complex systems.

ABSTRACT: Herein, Ca K-edge X-ray absorption spectroscopy (XAS) is developed as a means to characterize the local environment of calcium centers. The spectra for six, seven, and eight coordinate inorganic and molecular calcium complexes were analyzed and determined to be primarily influenced by the coordination environment and site symmetry at the calcium center. The experimental results are closely correlated to time-dependent density functional theory (TD-DFT) calculations of the XAS spectra. The applicability of this methodology to complex systems was investigated using structural mimics of the oxygen-evolving complex (OEC) of PSII. It was found that Ca K-edge XAS is a sensitive probe for structural changes occurring in the cubane heterometallic cluster due to Mn oxidation. Future applications to the OEC are discussed.

SUBMITTER: Martin-Diaconescu V

PROVIDER: S-EPMC4331723 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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Ca K-edge XAS as a probe of calcium centers in complex systems.

Martin-Diaconescu Vlad V Gennari Marcello M Gerey Bertrand B Tsui Emily E Kanady Jacob J Tran Rosalie R Pécaut Jacques J Maganas Dimitrios D Krewald Vera V Gouré Eric E Duboc Carole C Yano Junko J Agapie Theodor T Collomb Marie-Noelle MN DeBeer Serena S

Inorganic chemistry 20141210 4

Herein, Ca K-edge X-ray absorption spectroscopy (XAS) is developed as a means to characterize the local environment of calcium centers. The spectra for six, seven, and eight coordinate inorganic and molecular calcium complexes were analyzed and determined to be primarily influenced by the coordination environment and site symmetry at the calcium center. The experimental results are closely correlated to time-dependent density functional theory (TD-DFT) calculations of the XAS spectra. The applic ...[more]

PMID: 25492398

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