Template Effect of Chain-Type Polyamines on Pore Augmentation: Five Open-Framework Zinc Phosphates with 16-Ring Channels

Five new zinc phosphates with differently unique 3D framework topologies, (H₃dien)[Zn₃(HPO₄)₃(PO₄)] (1), (H₂dien)_1.5[Zn₃(HPO₄)₃(PO₄)] (2), (H₃dien)[Zn₃(H₂PO₄)(HPO₄)(PO₄)₂] (3), (H₃dien)[Zn₃(HPO₄)₃(PO₄)]·1.5H₂O (4), and (H₄tepa)_0.5[Zn_2.5(HPO₄)₂(PO₄)]·1.5H₂O (5), where dien = H₂NC₂H₄NHC₂H₄NH₂ and tepa = H₂N(C₂H₄NH)₃C₂H₄NH₂, have been synthesized under mild hydrothermal or solvothermal conditions and characterized by single-crystal X-ray diffraction, thermal analysis, solid-state NMR, UV–vis, or photoluminescence spectroscopy. Both the 7-atom-skeleton-long dien and the 13-atom-skeleton-long tepa have created 16-membered ring (16R) channels as a common feature in structures 1–5. Their inorganic frameworks are built up with tetrahedra of ZnO₄, PO₄, and HPO₄ (plus H₂PO₄ in 3) and may all be described as constructed from two-dimensional nets and one- or zero-dimensional units as linkers. Compounds 1–4 have the same Zn/P ratio but possess varied amount of nonframework volume. They are the first examples with dien as template in extra-large-channel structures of zincophosphates. In comparison, the framework of 5 contains a higher value in Zn/P and larger nonframework volume than that in the 24R-channel structure of ND-1. The 16R channels in 1 and 2 are one-dimensional while those in 3, 4, and 5 are unprecedentedly two-dimensional. In this paper, the synthesis, thermal property, NMR, reflectance UV–vis absorption, and photoluminescence study of 1–5 are described; framework topologies, structure relationship, the charge and location of templates, and channel characteristic vs nonframework volume are discussed.