Extending Unique 1D Borate Chains to 3D Frameworks by Introducing Metallic Nodes

Two novel alkali/alkaline‐earth borates, Ba 6 [B 6 O 9 (OH) 6 ] 2 (H 3 BO 3 ) ( 1 ) and Li 7 MAlB 12 O 24 (M=Ba, Sr, Ca) ( 2 a – c ), with 1D and 3D structures have been made hydrothermally and characterized. 1 features a rare 1D anionic chain built by hexaborate clusters of B 6 O 11 (OH) 6 ; each made of six BO 4 /BO 2 (OH) 2 tetrahedra. The anionic chains are embedded in the channels of a Ba 6 ‐based wheel‐cluster open‐framework. On the basis of the structural analyses of 1 , by incorporating Al atoms as the linkers and tuning the reaction conditions, the novel anhydrous 3D aluminoborates (ABOs) 2 a – c have been successfully obtained, constructed from B 6 O 14 ‐based cluster chains and AlO 6 octahedra. The 3D ABO framework and 3D Ba‐O‐Li network are interpenetrated to give a final dense structure. The study not only realized the expansion of the structure from the 1D chain of 1 to the 3D dense ABOs 2 a – c , but also obtained the first 3D AlO 6 ‐containing ABOs made under hydrothermal conditions. Different from the previously known 4‐connected zeolite‐type ABOs, alternately arranged from AlO 4 tetrahedra and oxo‐boron clusters, the AlO 6 octahedra in 2 a – c as the linkers join to six 1D B 6 O 14 ‐based cluster chains to produce 3D ABOs. The optical diffuse reflectance spectra reveal that 2 a – c have wide range transparency. In addition, the thermal property analysis proves that 2 a – c are congruently melting compounds and possess high thermostability.