Solid-State 91Zr NMR Characterization of Layered and Three-Dimensional Framework Zirconium Phosphates

Layered and open framework zirconium phosphates (ZrPs) have many current and potential applications in the areas of catalysis, sorption, protonic conductors, solar energy storage, crystal engineering, and ion exchange. Characterization of ZrP-based materials is important because understanding the relationship between the properties of these materials and their structures is crucial for developing new uses and for improving their performances in current applications. However, local Zr environments in many ZrPs have not been characterized directly by 91Zr solid-state NMR (SSNMR). This is because 91Zn (I = 5/2) is an unreceptive nucleus with many NMR unfavorable characteristics, leading to low sensitivity. In this work, the local environments of the zirconium centers in several ion-exchanged derivatives of layered α-ZrP (K+-, Li+-, Co(NH3)63+-ZrP) have been probed directly using 91Zr MAS, static quadrupolar echo, and/or quadrupolar Carr–Purcell–Meiboom–Gill NMR. Several layered and three-dimensional framewor...