Borates A Novel Twofold Interpenetrating 3D Diamondoid Borate Framework Constructed from B4and B5Clusters

Borates with extended structures and interpenetrating system built from different types of cluster units are extremely rare. In this paper, we report a novel mixed-alkali-metal borate Na3Li2[B4O7][B5O8(OH)2] (1) synthesized under solvothermal conditions, showing a three-dimensional twofold interpenetrating system constructed from two types of oxoboron clusters (B4O9 and B5O10(OH)2) setting as the first example in borates. And 1 also features an intricate 3-D Li-O−Na cationic network. In this work, we made a detailed comparison with other reported borates from 1-D chain, 2-D layer to 3-D framework containing B4 and B5 clusters and further demonstrated that such 3-D framework of 1 can be achieved by controlling the alkalinity of solution to prompt the concentration of two different oxoboron clusters with rich terminal hydroxyl groups together. Indeed, it can be regarded as a good interpretation of hydrolysis-condensation processes in dimensional transformation of borates making it possible for the rational design of various structural borates in the future. Moreover, 1 displays fluorescence emission around 472 nm, making it an appropriate candidate for optoelectronic applications.