Irradiation Accelerated Hydrolysis of Soluble Keplerate Titanium-Bismuth Oxo Clusters with Complete Surface Ligands...

Controlled hydrolysis of metal oxo clusters has been first applied as a direct nanopatterning strategy for oxide materials. A heterometallic Bi₄Ti₁₂ oxo cluster is constructed with Keplerian-type architecture as a molecular platform for post-synthetic reactivity studies. Detailed mass spectrometry analysis confirms its exceptional dissolution stability and complete surface alkoxy ligands exchangeability. Interestingly, spin-coated thin films of Bi₄Ti₁₂ oxo clusters exhibit significant solubility contrast after ambient condition hydrolysis. Accordingly, electron-beam irradiation is applied to accelerate the cluster hydrolysis in exposed areas to enable fine lines patterning, with the hydrolysis-condensation pathways of irradiated Bi₄Ti₁₂ oxo clusters being demonstrated by comparative spectroscopic analyses. Finally, 20 nm critical dimension (CD) lines can be fabricated using this method under an expose energy of 130 µCcm^{- 2}. Therefore, this work not only constructs a Keplerate cluster family with interesting complete surface ligand exchange behavior, but also provides a new metal hydrolysis-driven lithography strategy for the direct patterning of metal oxide nanostructures.