Hydrogen-bonded networks in crystals built from bis(biguanides) and their salts

2006 ◽  
Vol 84 (10) ◽  
pp. 1426-1433 ◽  
Author(s):  
Olivier Lebel ◽  
Thierry Maris ◽  
James D Wuest

Biguanide groups and biguanidinium cations incorporate multiple sites that can donate or accept hydrogen bonds. To assess their ability to associate and to direct the formation of extended hydrogen-bonded networks, we examined the structure of crystals of four compounds in which two neutral biguanide groups or the corresponding cations are attached to the 1,4- and 1,3-positions of phenylene spacers. As expected, all four structures incorporate extensive networks of hydrogen bonds and reveal other reliable features. In particular, (1) neutral biguanide groups favor a roughly planar conformation with an intramolecular hydrogen bond, and they associate as hydrogen-bonded pairs, (2) despite coulombic repulsion, biguanidinium cations can also associate as hydrogen-bonded pairs, and (3) the 1,3-phenylenebis(biguanidinium) dication favors a pincerlike conformation that allows chelation of suitable counterions. However, the precise patterns of hydrogen bonding in the structures vary substantially, limiting the usefulness of biguanide and biguanidinium as groups for directing supramolecular assembly.Key words: bis(biguanide), bis(biguanidinium), structure, hydrogen-bonded network, noncovalent interaction, supramolecular chemistry, crystal engineering.

2004 ◽  
Vol 60 (4) ◽  
pp. 438-446 ◽  
Author(s):  
Shaleen Bawa ◽  
Marie L. Coté ◽  
Patrick Dubois ◽  
Roger A. Lalancette ◽  
Hugh W. Thompson

The monohydrate of the title phenolic diacid (C8H6O5·H2O, 2-hydroxybenzene-1,3-dioic acid or 3-carboxysalicylic acid) adopts a planar conformation, with the phenol hydrogen internally hydrogen-bonded to the carbonyl of one highly ordered carboxyl, which, in turn, donates a hydrogen bond to the oxygen of water. The second carboxyl is disordered and hydrogen-bonded both to water and to the disordered carboxyl of a centrosymmetrically related neighbor in a static disorder arrangement extending over two full asymmetric units. The water accepts either one or two hydrogen bonds and donates a long bifurcated hydrogen bond shared equally by O atoms of the phenol and the disordered carboxyl. The hydrogen bonding includes no standard carboxyl pairing and is entirely two-dimensional. The resulting planar ribbons stack translationally at a distance of 3.413 (8) Å, in an offset arrangement having non-translational interplanar distances of 0.821 (5) and 2.592 (6) Å. This structure is compared with two previously reported for this compound. The title compound forms a monoanion, whose tetraphenylphosphonium salt is described (C32H25O5P, tetraphenylphosphonium 2,6-dicarboxyphenolate, tetraphenylphosphonium 2-oxidoisophthalic acid or tetraphenylphosphonium 3-carboxysalicylate). The phenol oxygen is the site of formal negative charge on the anion, which is stabilized in a planar arrangement by symmetrical hydrogen bonds from both ortho-carboxyl groups. The energetics of this arrangement, the phenol and carboxyl acidities, and factors affecting those acidities and providing anion stabilization are discussed.


2005 ◽  
Vol 60 (4) ◽  
pp. 363-372 ◽  
Author(s):  
Athanassios K. Boudalis ◽  
Vassilios Nastopoulos ◽  
Catherine P. Raptopoulou ◽  
Aris Terzis ◽  
Spyros P. Perlepes

In order to examine the possibility of using yttrium(III) in the crystal engineering of hydrogenbonded coordination complexes and to compare the molecular and supramolecular YIII/Cl3 or NO3-/DMU chemistry with the already well-developed LnIII/Cl− or NO3−/DMU chemistry (LnIII = lanthanide, DMU = N,N’-dimethylurea), compounds [Y(DMU)6][YCl6] (1) and [Y(NO3)3(DMU)3] (2) have been prepared. The structures of both compounds have been determined by single-crystal Xray diffraction. The structure of 1 consists of octahedral [Y(DMU)6]3+ and [YCl6]3− ions. The YIII ion in 2 is nine-coordinate and ligation is provided by three O-bonded DMU ligands and three bidentate chelating nitrato groups; the coordination polyhedron about the metal can be viewed as a distorted, monocapped square antiprism. The [Y(DMU)6]3+ cations and [YCl6]3− anions self-assemble to form a hydrogen-bonded 3D architecture in 1. Most of the hydrogen-bonding functionalities on the components of 2 create also a 3D network. Two motifs of interionic/intramolecular hydrogen-bonds have been observed: N-H···Cl in 1 and N-H···O(NO3−) in 2. The IR data are discussed in terms of the nature of bonding and the structures of the two complexes


2018 ◽  
Vol 74 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Wilhelm Maximilian Hützler ◽  
Michael Bolte

Doubly and triply hydrogen-bonded supramolecular synthons are of particular interest for the rational design of crystal and cocrystal structures in crystal engineering since they show a high robustness due to their high stability and good reliability. The compound 5-methyl-2-thiouracil (2-thiothymine) contains an ADA hydrogen-bonding site (A = acceptor and D = donor) if the S atom is considered as an acceptor. We report herein the results of cocrystallization experiments with the coformers 2,4-diaminopyrimidine, 2,4-diamino-6-phenyl-1,3,5-triazine, 6-amino-3H-isocytosine and melamine, which contain complementary DAD hydrogen-bonding sites and, therefore, should be capable of forming a mixed ADA–DAD N—H...S/N—H...N/N—H...O synthon (denoted synthon 3s N·S;N·N;N·O), consisting of three different hydrogen bonds with 5-methyl-2-thiouracil. The experiments yielded one cocrystal and five solvated cocrystals, namely 5-methyl-2-thiouracil–2,4-diaminopyrimidine (1/2), C5H6N2OS·2C4H6N4, (I), 5-methyl-2-thiouracil–2,4-diaminopyrimidine–N,N-dimethylformamide (2/2/1), 2C5H6N2OS·2C4H6N4·C3H7NO, (II), 5-methyl-2-thiouracil–2,4-diamino-6-phenyl-1,3,5-triazine–N,N-dimethylformamide (2/2/1), 2C5H6N2OS·2C9H9N5·C3H7NO, (III), 5-methyl-2-thiouracil–6-amino-3H-isocytosine–N,N-dimethylformamide (2/2/1), (IV), 2C5H6N2OS·2C4H6N4O·C3H7NO, (IV), 5-methyl-2-thiouracil–6-amino-3H-isocytosine–N,N-dimethylacetamide (2/2/1), 2C5H6N2OS·2C4H6N4O·C4H9NO, (V), and 5-methyl-2-thiouracil–melamine (3/2), 3C5H6N2OS·2C3H6N6, (VI). Synthon 3s N·S;N·N;N·O was formed in three structures in which two-dimensional hydrogen-bonded networks are observed, while doubly hydrogen-bonded interactions were formed instead in the remaining three cocrystals whereby three-dimensional networks are preferred. As desired, the S atoms are involved in hydrogen-bonding interactions in all six structures, thus illustrating the ability of sulfur to act as a hydrogen-bond acceptor and, therefore, its value for application in crystal engineering.


Author(s):  
Ping Su ◽  
Xue-gang Song ◽  
Ren-qiang Sun ◽  
Xing-man Xu

The asymmetric unit of the title organic salt [systematic name: 1H-pyrazol-2-ium 2,4,6-trinitrophenolate–1H-pyrazole (1/1)], H(C3H4N2)2+·C6H2N3O7−, consists of one picrate anion and one hydrogen-bonded dimer of a pyrazolium monocation. The H atom involved in the dimer N—H...N hydrogen bond is disordered over both symmetry-unique pyrazole molecules with occupancies of 0.52 (5) and 0.48 (5). In the crystal, the component ions are linked into chains along [100] by two different bifurcated N—H...(O,O) hydrogen bonds. In addition, weak C—H...O hydrogen bonds link inversion-related chains, forming columns along [100].


1993 ◽  
Vol 328 ◽  
Author(s):  
Mike Zaworotko ◽  
S. Subramanian ◽  
L. R. Macgillivray

ABSTRACTCrystal engineering has been invoked to design structural analogues of two prototypal SHG active solids, p-nitroaniline (pNA) and potassium dihydrogenphosphate (KDP). pNA exists as linear polar strands because of head-to-tail hydrogen bonding between adjacent molecules whereas KDP is a self-assembled hydrogen bonded diamondoid network that becomes polar when the hydrogen bonds align. We detail preparation and crystallographic characterization of two classes of multicomponent solid, organic cation hydrogen sulfates and cocrystals of the cubane cluster [M (CO)3(μ3-OH)]4, which structurally mimic pNA and KDP, respectively. Several of the Multi-component solids are polar and they represent a generic approach to designing new polar materials since one component can be changed without altering the basic architecture within the crystal.


1990 ◽  
Vol 68 (1) ◽  
pp. 266-273 ◽  
Author(s):  
L. C. Stewart ◽  
M. Kates ◽  
P. W. Yang ◽  
H. H. Mantsch

A series of diphytanylglycerol phospholipids, i.e., diphytanylglycerol phosphate (PA), diphytanylglycerol phosphoglycerophosphate (PGP), the tri- and tetra-methyl derivatives of PGP, and the 2-deoxyglycerol analogue of PGP (dPGP) were studied by Fourier transform infrared spectroscopy. The use of the "deoxy" and methylated analogues of PGP, as well as that of PA and PGP of varying degrees of ionization, allowed the assignment of characteristic infrared bands associated with the phosphate groups. Analysis of these phosphate bands showed that at neutral pH, each of the two phosphate moieties in PGP is singly ionized, whereas in dPGP the phosphomonoester is doubly ionized. This is a consequence of the marked increase in the pK of one of the P-OH groups on the terminal phosphate of PGP (pK > 11), owing to the formation of an intramolecular hydrogen bond between the head group glycerol hydroxyl and the phosphate groups of PGP. Such an intramolecular hydrogen bond can not be formed by the dPGP analogue, and thus both negative charges in dPGP are located at the terminal phosphomonoester group. The O=P—OH groups of PGP also forms a network of intermolecular hydrogen bonds, the exact nature of which depends on concentration and degree of ionization. The possibility of a complex network of hydrogen bonds within (intramolecular) and between (intermolecular) anionic membrane lipids such as that found in PGP, is consistent with the hypothesis that these lipids function as proton-conducting pathways in membranes.Key words: phospholipids, infrared, hydrogen bonding, phosphatidylglycerophosphate, 2-deoxyphosphatidylglycerophosphate.


1960 ◽  
Vol 38 (8) ◽  
pp. 1249-1254 ◽  
Author(s):  
L. W. Reeves ◽  
E. A. Allan ◽  
K. O. Strømme

Nuclear shielding parameters have been obtained for 24 intramolecularly hydrogen-bonded phenols and naphthols. The shielding parameters are corrected for large diamagnetic anisotropies and a value ΔσOH obtained which represents the change in shielding parameter in parts per million with reference to the infinite dilution chemical shift of phenol, α-naphthol, or β-naphthol. These values of ΔσOH are approximately proportional to the change ΔvOH in the OH stretching frequency on formation of the hydrogen bond.


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