Four Inorganic-Organic Hybrid Borates: From 2D Layers to 3D Oxoboron Cluster Organic Frameworks.

Four inorganic-organic hybrid borates, K[B6O9(OH)(en)]·H2O (1, en = ethylenediamine), K[B6O9(OH)(1,3-dap)]·H2O (2, 1,3-dap = 1,3-diaminopropane), K[B6O9(OH)(1,6-dah)0.5]·H2O (3, 1,6-dah = 1,6-diaminlhexane) and [(1,3-dap)Cd@B5O8(OH)]·0.5H2O (4), were made under solvothermal conditions. 1 and 2 are isostructural and feature a 2D layer built by B6O9(OH) clusters and modified by en and 1,3-dap via B-N-C linkages. By replacing en and 1,3-dap with longer and more flexible 1,6-dah, a new type of oxoboron cluster organic framework 3 was obtained, which was composed of the same B6O9(OH) cluster layers as in 1 and 2 and 1,6-dah linkers. By replacing alkali metal K with transition metal Cd under similar synthetic conditions, another type of oxoboron cluster organic framework 4 was made in which the Cd-centered wheel cluster layers and 1,3-dap linkers were connected via Cd-N-C linkages.