Photoactivation of Titanium-oxo Cluster [TiO(OR)(OC Bu)]: Mechanism, Photoactivated Structures, and Onward Reactivity with O to a Peroxide Complex

Overview

Journal Chem Sci

Publisher Royal Society of Chemistry

Specialty Chemistry

Date 2023 Feb 6

PMID 36741534

Authors

Stephen E Brown

Ioanna Mantaloufa

Ryan T Andrews

Thomas J Barnes

Martin R Lees

Frank De Proft

Ana V Cunha

Sebastian D Pike

Affiliations

Soon will be listed here.

Abstract

The molecular titanium-oxo cluster [TiO(OPr)(OC Bu)] (1) can be photoactivated by UV light, resulting in a deeply coloured mixed valent (photoreduced) Ti (iii/iv) cluster, alongside alcohol and ketone (photooxidised) organic products. Mechanistic studies indicate that a two-electron (not free-radical) mechanism occurs in this process, which utilises the cluster structure to facilitate multielectron reactions. The photoreduced products [TiO(OPr)(OC Bu)(sol)], sol = PrOH (2) or pyridine (3), can be isolated in good yield and are structurally characterized, each with two, uniquely arranged, antiferromagnetically coupled d-electrons. 2 and 3 undergo onward oxidation under air, with 3 cleanly transforming into peroxide complex, [TiO(OPr)(OC Bu)(py)(O)] (5). 5 reacts with isopropanol to regenerate the initial cluster (1) completing a closed cycle, and suggesting opportunities for the deployment of these easily made and tuneable clusters for sustainable photocatalytic processes using air and light. The redox reactivity described here is only possible in a cluster with multiple Ti sites, which can perform multi-electron processes and can adjust its shape to accommodate changes in electron density.

Citing Articles

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References

Fan X, Fu H, Zhang L, Zhang J . Pyrazole-thermal synthesis: a new approach towards N-rich titanium-oxo clusters with photochromic behaviors. Dalton Trans. 2019; 48(23):8049-8052. DOI: 10.1039/c9dt01628g. View

Saouma C, Tsou C, Richard S, Ameloot R, Vermoortele F, Smolders S . Sodium-coupled electron transfer reactivity of metal-organic frameworks containing titanium clusters: the importance of cations in redox chemistry. Chem Sci. 2019; 10(5):1322-1331. PMC: 6354900. DOI: 10.1039/c8sc04138e. View

Fan Y, Cui Y, Zou G, Duan R, Zhang X, Dong Y . A ferrocenecarboxylate-functionalized titanium-oxo-cluster: the ferrocene wheel as a sensitizer for photocurrent response. Dalton Trans. 2017; 46(25):8057-8064. DOI: 10.1039/c7dt01756a. View

Peper J, Gentry N, Boudy B, Mayer J . Aqueous TiO Nanoparticles React by Proton-Coupled Electron Transfer. Inorg Chem. 2021; 61(2):767-777. DOI: 10.1021/acs.inorgchem.1c03125. View

Dakanali M, Kefalas E, Raptopoulou C, Terzis A, Voyiatzis G, Kyrikou I . A new dinuclear Ti(IV)-peroxo-citrate complex from aqueous solutions. Synthetic, structural, and spectroscopic studies in relevance to aqueous titanium(IV)-peroxo-citrate speciation. Inorg Chem. 2003; 42(15):4632-9. DOI: 10.1021/ic0343051. View

Fang W, Zhang L, Zhang J . Synthetic strategies, diverse structures and tuneable properties of polyoxo-titanium clusters. Chem Soc Rev. 2017; 47(2):404-421. DOI: 10.1039/c7cs00511c. View

Amtawong J, Skjelstad B, Balcells D, Don Tilley T . Concerted Proton-Electron Transfer Reactivity at a Multimetallic CoO Cubane Cluster. Inorg Chem. 2020; 59(20):15553-15560. DOI: 10.1021/acs.inorgchem.0c02625. View

Hong K, Bak W, Chun H . Robust molecular crystals of titanium(IV)-oxo-carboxylate clusters showing water stability and CO2 sorption capability. Inorg Chem. 2014; 53(14):7288-93. DOI: 10.1021/ic500629y. View

Tomita K, Petrykin V, Kobayashi M, Shiro M, Yoshimura M, Kakihana M . A water-soluble titanium complex for the selective synthesis of nanocrystalline brookite, rutile, and anatase by a hydrothermal method. Angew Chem Int Ed Engl. 2006; 45(15):2378-81. DOI: 10.1002/anie.200503565. View

10.

Biswas S, Husek J, Londo S, Robert Baker L . Highly Localized Charge Transfer Excitons in Metal Oxide Semiconductors. Nano Lett. 2018; 18(2):1228-1233. DOI: 10.1021/acs.nanolett.7b04818. View

11.

Bueken B, Vermoortele F, Vanpoucke D, Reinsch H, Tsou C, Valvekens P . A Flexible Photoactive Titanium Metal-Organic Framework Based on a [Ti(IV)3(μ3-O)(O)2(COO)6] Cluster. Angew Chem Int Ed Engl. 2015; 54(47):13912-7. DOI: 10.1002/anie.201505512. View

12.

Gao M, Zhang L, Zhang J . Acid-Controlled Synthesis of Carboxylate-Stabilized Ti -Oxo Clusters: Scaling up Preparation, Exchangeable Protecting Ligands, and Photophysical Properties. Chemistry. 2019; 25(44):10450-10455. DOI: 10.1002/chem.201901671. View

13.

Mason J, Darago L, Lukens Jr W, Long J . Synthesis and O2 Reactivity of a Titanium(III) Metal-Organic Framework. Inorg Chem. 2015; 54(20):10096-104. DOI: 10.1021/acs.inorgchem.5b02046. View

14.

Aleisa R, Feng J, Ye Z, Yin Y . Rapid High-Contrast Photoreversible Coloration of Surface-Functionalized N-Doped TiO Nanocrystals for Rewritable Light-Printing. Angew Chem Int Ed Engl. 2022; 61(28):e202203700. DOI: 10.1002/anie.202203700. View

15.

Zhou S, Li C, Fu H, Cao J, Zhang J, Zhang L . Lead-Doped Titanium-Oxo Clusters as Molecular Models of Perovskite-Type PbTiO and Electron-Transport Material in Solar Cells. Chemistry. 2020; 26(30):6894-6898. DOI: 10.1002/chem.202000911. View

16.

Lv H, Cui Y, Zhang Y, Li H, Zou G, Duan R . A 4-dimethylaminobenzoate-functionalized Ti-oxo cluster with a narrow band gap and enhanced photoelectrochemical activity: a combined experimental and computational study. Dalton Trans. 2017; 46(36):12313-12319. DOI: 10.1039/c7dt02650a. View

17.

Nguyen H, Gandara F, Furukawa H, Doan T, Cordova K, Yaghi O . A Titanium-Organic Framework as an Exemplar of Combining the Chemistry of Metal- and Covalent-Organic Frameworks. J Am Chem Soc. 2016; 138(13):4330-3. DOI: 10.1021/jacs.6b01233. View

18.

Sachs M, Park J, Pastor E, Kafizas A, Wilson A, Francas L . Effect of oxygen deficiency on the excited state kinetics of WO and implications for photocatalysis. Chem Sci. 2019; 10(22):5667-5677. PMC: 6563783. DOI: 10.1039/c9sc00693a. View

19.

Naldoni A, Altomare M, Zoppellaro G, Liu N, Kment S, Zboril R . Photocatalysis with Reduced TiO: From Black TiO to Cocatalyst-Free Hydrogen Production. ACS Catal. 2019; 9(1):345-364. PMC: 6344061. DOI: 10.1021/acscatal.8b04068. View

20.

Benedict J, Coppens P . The crystalline nanocluster phase as a medium for structural and spectroscopic studies of light absorption of photosensitizer dyes on semiconductor surfaces. J Am Chem Soc. 2010; 132(9):2938-44. DOI: 10.1021/ja909600w. View