Syntheses, Structures and Properties of Two New Members of the Pentaborate Family, NaKB5O8(OH)•H2O and KB5O8•2H2O

Abstract

Two new members of the pentaborate family, NaKB5O8(OH)•H2O (I) and KB5O8•2H2O (II), were successfully synthesized, which crystallize in the space groups of P"1" @#x0305; and Fddd, respectively. In compound I, [B5O10(OH)] fundamental building blocks (FBBs) constitute the two-dimensional (2D) 2[B5O8(OH)]∞ layer through corner-sharing, whereas in compound II, [B5O10] FBBs form two independent interpenetrating 3D 3[B5O8]∞ networks by sharing common O atoms. The UV−vis−NIR diffuse reflectance spectrum and first-principles calculations suggest that the two compounds possess deep-ultraviolet (DUV) transparency windows. The real-space atom-cutting and the response electron distribution anisotropy (REDA) analyses show that the birefringence of both compounds mainly originates from the π-conjugated units.