Designable Al₃₂‐Oxo Clusters with Hydrotalcite‐like Structures: Snapshots of Boundary Hydrolysis and Optical Limiting

Abstract

The hydrolysis of earth‐abundant AlIII has implications in mineral mimicry, geochemistry and environmental chemistry. Third‐order nonlinear optical (NLO) materials are important in modern chemistry due to their extensive optical applications. The assembly of AlIII ions with π‐conjugated carboxylate ligands is carried out and the hydrolysis and NLO properties of the resultant material are studied. A series of Al32‐oxo clusters with hydrotalcite‐like cores and π‐conjugated shells are isolated. X‐ray diffraction revealed boundary hydrolysis occurs at the equatorially unsaturated coordination sites of AlIII ions. Charge distribution analysis and DFT calculations support the proposed boundary substitution. The Al32‐oxo clusters possess a significant reverse saturable absorption (RSA) response with a minimal normalized transmittance up to 29 %, indicating they are suitable candidates for optical limiting (OL) materials. This work elucidates the hydrolysis of AlIII and provides insight into layered materials that also have strong boundary activity at the edges or corners.

Polyoxometalates with tunable third-order nonlinear optical and superbroadband optical limiting properties

“…17 Recently, a series of Al 32 -oxo clusters with hydrotalcite-like structure has been reported to exhibit NLA and OL to a nanosecond laser at 532 nm. 18 To the best of our knowledge, no molecular clusters with broadband OL have been reported up to now.…”

Solvent-controlled synthesis of an Al12-oxo molecular ring and Al24-oxo truncated metallo-cube

“…31 For this dilemma, recently, a new strategy known as coordination delayed hydrolysis has been adopted by Zhang et al to synthesize a series of Al-oxo clusters by choosing monodentate carboxylic acid ligands and organic aluminium salts under solvothermal conditions. [32][33][34][35] Most of these Al-oxo clusters feature the structures of molecular rings from Al 8 to the largest Al 20 constructed using different large conjugated carboxylic acids. 33,34,36 The different peripheral ligands realize luminescence modulation of Al 20 molecular rings from blue to green.…”

Silver‐Templated γ‐Keggin Alkyltin‐Oxo Cluster: Electronic Structure and Optical Limiting Effect

“…The calculated nonlinear absorption coefficient β value of AgSn 12 is � 2.55 × 10 À 8 m W À 1 , which is comparable to the Al-oxo clusters but larger than some transition metal clusters. [43,44] And the optical limiting threshold (F OL ) of AgSn 12 sample is 0.502 J cm À 2 (Figure 4d).…”