Metal phosphite containing 24-ring channels with 10-ring windows

Cr-NKU-24, a metal phosphite, containing 24-ring channels was formed from the coiling of a net with 10-ring windows. Cr-NKU-24 was synthesized hydrothermally from a mixture of ZnO, CrCl3, pseudoboehmite, H 3PO3, H2O and cyclohexylamine (CHA) with a typical molar ratio. Single crystal analysis has revealed that the framework of Cr-NKU-24 consisted of Zn2Al0.57Cr 0.10(HPO3)4 with C6H 11NH3+ as the charge compensator and it crystallized in the hexagonal space group. The occupancy value of Cr was determined from the fragment with the inductively coupled plasma (ICP) result. The result shows that the replacement of tetrahedral phosphate groups PO43- by pyramidal phosphite units HPO32- can reduce the M-O-P connectivity and generate more-open interrupted framework structures to form extra-large microporous materials.