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The crystal structures of three proton-transfer compounds of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid) with 4-X-substituted anilines (X = F, Cl and Br), namely 4-fluoroanilinium 5-sulfosalicylate (3-carboxy-4-hydroxyben- zenesulfonate) monohydrate, C6H7FN+·C7H5O6S¯·H2O, (I), 4-chloroanilinium 5-sulfosalicylate hemihydrate, C6H7C1-N+C7H5O6S¯0.5H2O, (II), and 4-bromoanilinium 5-sulfo-salicylate monohydrate, C6H7BrN+·C7H5O6S¯·H2O, (III), have been determined. The asymmetric unit in (II) contains two formula units. All three compounds have three-dimensional hydrogen-bonded polymeric structures in which both the water molecule and the carboxylic acid group are involved in structure extension. With both (II) and (III), which are structurally similar, the common cyclic R²2(8) dimeric carboxylic acid association is present, whereas in (I), an unusual cyclic R³3(8) association involving all three hetero- species is found. [ABSTRACT FROM AUTHOR]

The structures of two pseudopolymorphic hydrates of brucine, C23H26N2O4·4H2O, (I), and C23H26N2O4·5.25H2O, (II), have been determined at 130 K. In both (I) and (II) (which has two independent brucine mol­ecules together with 10.5 water mol­ecules of solvation in the asymmetric unit), the brucine mol­ecules form head-to-tail sheet substructures, which associate with the water mol­ecules in the inter­stitial cavities through hydrogen-bonding associations and, together with water–water associations, give three-dimensional framework structures. [ABSTRACT FROM AUTHOR]

In the title compound, C9H8N+·C6H7O7−, the dihydrogen citrate anions form a convoluted two-dimensional hydrogen-bonded substructure through head-to-tail interactions with the interstitial π-stacked quinolinium cations linked to it peripherally through cyclic R12(5) N+—H...O(carboxyl/hydroxyl) hydrogen-bond interactions. The loss of a proton from one of the β-carboxylic acid groups of the citric acid generates a chiral centre in the anion, but these form a racemate in the centrosymmetric crystal structure. [ABSTRACT FROM AUTHOR]

Abstract: The supramolecular interactions of the planar guanidinium cation () with benzenesulphonate (1), -phosphonate (2) and -arsonate (3) anions, and several of their 3- and 4-nitro-substituted derivatives is reported. In all cases well-defined crystalline materials, containing hydrogen-bonded networks with quasi-hexagonal sheet lattices were formed. However, the unsubstituted sulphonate (1) formed a 1:1 guanidinium:sulphonate bilayer structure, whilst the unsubstituted phosphonate (2) and arsonate (3) formed 2:1 guanidinium:phosphonate/arsonate single-layer structures with water occluded within the crystal voids. The additional H-bonding interactions resulting in distortion of the crystal voids in (2)/(3) as compared to the symmetrical hexagonal-form in (1). In the case of the nitro-substituted sulphonate derivatives, the 1:1 bilayer structure of the parent (1) was retained for the 3-nitrobenzenesulphonate (4), but transformed to a 1:1 single-layer system for the 4-nitrobenzenesulphonate (6). The reverse was observed for the nitrated phosphonic acids, whereby the 4-nitrobenzenephosphonate anion in (5) caused little disruption to the 2:1 single-layered structure and quasi-hexagonal sheet seen in (2), but the 3-nitrobenzenephosphonate caused a breakdown of the network forming a new, complex ribbon system (7). The greater complexity of the P/As (−2) structures compared to the S (−1) structure is attributed to the higher charge on the former anions providing additional opportunities for H-bonding. The observation of such interactions clearly indicates the likelihood of such species interacting with biologically-important arginine residues in vivo with concomitant unintended, but likely, toxic consequences. [Copyright &y& Elsevier]

Abstract: The crystal structure and spectroscopic characteristics of n-octanohydroxamic acid and the potassium compound of that acid have been investigated by XRD, XPS, FTIR and Raman spectroscopy. XRD revealed that the acid is in the keto Z conformation with the alkyl chains oriented along the z-direction and hydrogen bonding between hydroxamate moieties. Vibrational spectra confirm this conclusion. Chemical analysis, XRD and XPS established that the potassium compound is the acid salt KH(C7H9CONO)2. The crystal structure showed that the hydroxamate groups are also in the keto Z conformation and this is supported by vibrational spectra. In the acid salt, the two hydroxamate moieties are connected by a symmetrical O–H–O short hydrogen bonded linkage between the two hydroxamate oxygen atoms and this explains the absence of a discernible O–H stretch band in the vibrational spectra. Identification of the vibrational bands displayed is supported by deuteration and 15N substitution. [Copyright &y& Elsevier]

Guanidinium 4-nitro­anthranilate monohydrate, CH6N3+·C7H5N2O4−·H2O, determined at 130 K, forms a primary hydrogen-bonded ribbon structure through cyclic hydrogen-bonding inter­actions involving all six protons of the guanidinium cation with the amino N-atom and carboxyl­ate O-atom acceptors of the anion, and the water mol­ecule of solvation. Other inter­actions, including the water mol­ecule bridging the primary ribbons, give a three-dimensional structure. [ABSTRACT FROM AUTHOR]

The crystal structure of a non-centrosymmetric polymorphic modification of the title compound, C9H7NO4, determined at 130 K, shows the presence of 21 screw-generated one-dimensional zigzag chains formed through catemeric C(4) syn– anti carboxylic acid hydrogen-bonding associations. [ABSTRACT FROM AUTHOR]

The structure of the title, compound C23H27N2O4+·C8H5O4−·3H2O, has been determined at 130 K. The hydrogen isophthalate anions and the water mol­ecules (one of which is disordered over two approximately equal sites) associate through extensive hydrogen-bonded inter­actions, including those with the common undulating brucinium cation layer substructures, forming a three-dimensional framework structure. [ABSTRACT FROM AUTHOR]