Anion-directed assembly: the first fluoride-directed double helix

Abstract

The crystal structures of anion complexes of two nitroaromatic functionalised isophthalamides are reported; the structures reveal assembly around anions in the solid-state and in the case of the fluoride complex of receptor 2, the formation of a double helix.

Synthesis and structure of fluorosilicic acid compounds with 4-aminobenzoic acid and with 4-aminobenzenesulfonamide

“…The family of hexafluorosilicates of aromatic bases is restricted to six compounds, in these compounds different numbers of fluorine atoms are involved in the system of hydrogen bonding. Thus, in bis(N,N 0 -bis(3-nitrophenyl)isophthalamide) tetra-n-butylammonium hexafluorosilicate [7], each [SiF 6 ] 2À anion is connected via its equatorial fluorine atoms within the crown-like cavity formed by two N,N 0 -bis(3-nitrophenyl)isophthalamide residues. In cocrystals with acridinium [8] and quinolinium [9] cations, only two or five over six fluorine atoms participate in hydrogen bond network.…”

The variations in hydrogen bonding in hexafluorosilicate salts of protonated methyl substituted pyridines and tetramethylethylenediamine

“…The electrostatic attractive forces between these cations and the anions [SiF 6 ] 2À facilitates the formation of extensive N-HÁ Á ÁF hydrogen-bond interactions [4][5][6][7][8][9][10][11][12][13][14]. The hydrogen bonds between ions are much stronger than between molecules and can play dominant roles in crystal structures [15].…”

“…Most of the known structures with [SiF 6 ] 2À exhibit extensive hydrogen-bonding networks that mainly incorporate all fluorine atoms of [SiF 6 ] 2À [4][5][6][7][8][9][10][11][12][13][14]23]. The nitrogen bases used in syntheses of 1, 2, and 4 are sterically demanding due to methyl groups on the basic nitrogen atom (4) or …”

Novel chemosensor for multiple target anions: The detection of F− and CN− ion via different approach

“…1 H NMR titrations were carried out in DMSO-d 6 . Tetra butyl ammonium salt of fluoride and cyanide were used as anions sources.…”

“…During the last few years, a number of colorimetric anion sensors have been developed using urea, thiourea, amide and pyrrole based binding units. Most of the receptors sense different anions such as fluoride, acetate, nitrate, dihydrogen phosphate and hydroxyl group [6][7][8][9][10][11][12]. Cyanide is one of the most toxic anion, harmful to the environment.…”