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Anionocages have been developed as a unique family of hydrogen bonded cages. However, strategies for constructing anionocages are mainly limited to that based on (PO43−)‐bisurea coordination, neither the ligands nor the anions lack the simplicity and diversity of the maturely developed analogues based on metal coordination (i.e. metallocage). We report herein a more simple strategy for anionocages design based on (RPO32−)‐monourea coordination, utilizing monourea rather than bisurea as the hydrogen binding donor, and RPO32− rather than PO43− as the acceptor. Two fluorescent, quadruple helicate anionocages were constructed by a bis‐monourea ligand, and dianions PhOPO32− (H1) or HOPO32− (H1A), respectively, which were capable of encapsulating a series of cation guests. As revealed by molecular modeling, H1 features remarkable guest‐adaptive cavity breathing without change of the quadruple helicate topology, which allowed the encapsulation of different sized guests in an "induced fit" manner. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title phospho­nium salt, C22H22O2P+·Br−·H2O, the triphenyl­phospho­sphonium group has three P—C bonds to phenyl rings which are equal within experimental error [mean 1.782 (3) Å] The P atom is also attached directly to the C atom of a 1,3-dioxan-2-ylmethyl group with a longer P—C bond of 1.800 (3) Å. The C—C bond of the dioxane ring [1.418 (5) Å] is shorter than the normal bond distance. The asymmetric unit contains two bromide anions on twofold rotation axes to balance the charge of the cation. [ABSTRACT FROM AUTHOR]