Insights of BO3–PO4 replacement for the design and synthesis of a new borate–phosphate with unique 1∞[Zn4BO11] chains and two new phosphates

Abstract

One new metal borate–phosphate, CsZn₄(BO₃)(PO₄)₂, and two new metal phosphates, CsZn₄(PO₄)₃ and RbZn₄(PO₄)₃, have successfully been synthesized by spontaneous crystallization with molten fluxes, and their structures were determined by single-crystal X-ray diffraction. These compounds exhibited three-dimensional frameworks; stacking of unique ¹_∞[Zn₄BO₁₁] mirror-image chains and isolated PO₄ tetrahedra for CsZn₄(BO₃)(PO₄)₂, and ¹_∞[Zn₄PO₁₂] chains and isolated PO₄ tetrahedra for CsZn₄(PO₄)₃ and RbZn₄(PO₄)₃. Interestingly, ¹_∞[Zn₄BO₁₁] is the first example in which the B atoms locate on the mirror axis of the image-symmetrical ¹_∞[Zn₄O₁₁] chains. Structure comparisons show that the substitution of BO₃–PO₄ is a feasible strategy for preparing new compounds, and the M/(B + P) ratio of compounds is a factor affecting the existence form of the anionic groups. Infrared spectra, thermal analysis, UV-vis-NIR diffuse reflectance spectroscopy, and first-principles calculations of the above three compounds are reported in this work.