Crystal structure of a host-guest complex of the tris-urea receptor, 3-(4-nitro-phen-yl)-1,1-bis-{2-[3-(4-nitro-phen-yl)ureido]eth-yl}urea, that encapsulates hydrogen-bonded chains of di-hydrogen phosphate anions with separate tetra-n-butyl-ammonium counter-ions.

ABSTRACT: The title compound, C₂₅H₂₅N₉O₉·C₁₆H₃₆N⁺·H₂PO₄ ^- (I) or (C₂₅H₂₅N₉O₉)·(n-Bu₄N⁺)·(H₂PO₄ ^-) (systematic name: 3-(4-nitro-phen-yl)-1,1-bis-{2-[3-(4-nitro-phen-yl)ureido]eth-yl}urea tetra-butyl-ammonium di-hydrogen phosphate), comprises a tris-urea receptor (R), a di-hydrogen phosphate anion and a tetra-n-butyl-ammonium cation. It crystallizes with two independent formula units in the asymmetric unit. The conformations of the two tris-urea receptors are stabilized by N-H?O and C-H?O intra-molecular hydrogen bonds. Each di-hydrogen phosphate anion has two O-H?O inter-molecular hydrogen-bonding inter-actions with the other di-hydrogen phosphate anion. Inversion-related di-anion units are linked by further O-H?O hydrogen bonds, forming a chain propagating along the a-axis direction. Each di-hydrogen phosphate anion makes a total of four N-H?O(H₂PO₄ ^-) hydrogen bonds with two ureido subunits from two different tris-urea receptors, hence each tris-urea receptor provides the two ureido subunits for the encapsulation of the H₂PO₄ ^- hydrogen-bonded chain. There are numerous inter-molecular C-H?O hydrogen bonds present involving both receptor mol-ecules and the tetra-n-butyl-ammonium cations, so forming a supra-molecular three-dimensional structure. One of the butyl groups and one of the nitro groups are disordered over two positions of equal occupancy.

SUBMITTER: Wang R 

PROVIDER: S-EPMC6399704 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature