Synthesis, Structures and Optical Limiting of Catecholato‐Based Aluminum Oxo Clusters

Present herein is the currently largest catecholato‐based aluminum oxo clusters. By adjusting the amount of auxiliary 3, 5‐dimethylpyrazole ligands, the synthesis of aluminum oxo clusters (AlOCs) (AlOC‐86) to high nuclearity AlOCs (AlOC‐88) were successfully achieved. Such synthetic strategy is applicable to imidazole ligands and new compounds (AlOC‐87 and AlOC‐89) were obtained. Single crystal analysis shows that AlOC‐86 and AlOC‐87 are hexanuclear clusters made up of two edge‐sharing tetrahedral clusters. The nuclearity of compounds AlOC‐88 and AlOC‐89 is doubled and they are S‐shape dodecanuclear AlOCs. The aggregation of such clusters is attributed to the labile sites on the two ends of the hexanuclear clusters. In addition, open aperture (OA) Z‐scan measurements results indicate that these compounds exhibit manifest reverse saturation absorption (RSA) response. The solvothermal synthesis of low nuclearity aluminum clusters to polynuclear aluminum clusters was achieved by regulating the amount of nitrogen‐containing ligands.