Novel open-framework fluorinated indium phosphate with 14-ring intersecting channels: Assembled from 6∗1 and racemic pillared secondary building units

Abstract

Templated by 4,4′-bipyridine (bipy), a new indium phosphate with an In/P ratio of 9/14 has been synthesized under hydrothermal conditions. The compound, In 9(HPO 4) 14(H 2O) 6F 3 · (C 10N 2H 9) 3 · (H 3O) · (H 2O) 2, crystallizes in the trigonal system with the space group P-31 c (No. 163) having cell parameters a = 13.9306(5) Å, c = 24.0435(12) Å, V = 4040.8(3) Å, and Z = 2 with R 1 = 0.0508. The overall structure consists of two types of secondary building units (SBUs): SBU-1, 6∗1, with a formula of [In 3(HPO 4) 4(H 2O) 3], constructs into a 4.6.12-net layer; and SBU-2, [In 3(HPO 4) 6F 3], features two [3.3.3] propellane-like chiral motifs with Δ and Λ configurations, forming an unprecedented racemic “pillar” unit. The layers are stacked in an ABAB sequence, penetrated by the pillar units perpendicularly, forming a 3-D pillared layer structure with a rectangular 14-ring channel system in two dimensions (along the [1 0 0] and [0 1 0] directions). Organic amine and fluorine ions play key roles in directing the formation of the structure, and the compound presents the same solid fluorescence properties as the bipy molecules attributing to the intraligand π–π ∗ transition.