The combination of racemic praziquantel, (RS)-PZQ, with aliphatic dicarboxylic acids of the homologous series HOOC−(CH 2 ) n −COOH (with n = 0−8) and the unsaturated analogues of succinic acid as cocrystal formers via liquid-assisted grinding provided a total of nine 1:1 and 2:1 cocrystals with oxalic acid, malonic acid, succinic acid (two polymorphic phases), maleic acid, fumaric acid, glutaric acid, adipic acid, and pimelic acid. The cocrystalline phases were identified first by XRPD analysis and then structurally characterized by IR spectroscopy and, as far as possible, by single-crystal X-ray diffraction analysis. Crystals suitable for XRD analysis were obtained for seven cocrystals and, additionally, for (RS)-PZQ. The analysis of the supramolecular interactions in the crystal structures has shown that the dominant hydrogen bonding patterns within the cocrystals are heterodimeric motifs formed through O−H•••O hydrogen bonds between PZQ and the dicarboxylic acids, which mostly contain additionally at least one secondary C−H•••O contact. In all crystal structures, the PZQ molecules are connected with each other through cyclic homodimeric hydrogen bonding interactions formed mainly through C−H•••O, but also through C−H•••π contacts, giving overall 1D, 2D or 3D hydrogen bonded networks. The crystallographic study also allowed us to establish that there are two main rotational conformers for PZQ, which differ in the configuration of the CO groups in the piperazinone−cyclohexylcarbonyl segment. In the crystal structure of (RS)-PZQ, all four independent molecules in the asymmetric unit have the syn-conformation, which in the hemihydrates, viz. (R)-PZQ•0.5H 2 O and (S)-PZQ•0.5H 2 O, and all cocrystals except for one are switched to the anti-antagonist.

In Mexico, local empirical knowledge about medicinal properties of plants is the basis for their use as home remedies. It is generally accepted by many people in Mexico and elsewhere in the world that beneficial medicinal effects can be obtained by ingesting plant products. In this review, we focus on the potential pharmacologic bases for herbal plant efficacy, but we also raise concerns about the safety of these agents, which have not been fully assessed. Although numerous randomized clinical trials of herbal medicines have been published and systematic reviews and meta-analyses of these studies are available, generalizations about the efficacy and safety of herbal medicines are clearly not possible. Recent publications have also highlighted the unintended consequences of herbal product use, including morbidity and mortality. It has been found that many phytochemicals have pharmacokinetic or pharmacodynamic interactions with drugs. The present review is limited to some herbal medicine that are native or cultivated in Mexico and that have significant use. We discuss the cultural uses, phytochemistry, pharmacological and toxicological properties of the following following plant species: Nopal (Opuntia ficus), Peppermint (Mentha piperita), Chaparral (Larrea divaricata), Dandlion (Taraxacum officinale), Mullein (Verbascum densiflorum), Chamomile (Matricaria recutita), Nettle or Stinging Nettle (Urtica dioica), Passionflower (Passiflora incarmata), Linden Flower (Tilia europea), and Aloa (Aloa vera). We conclude that our knowledge of the therapeutic benefits and risks of some herbal medicines used in Mexico is still limited and efforts to elucidate them should be intensified.

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A total of 20 co-crystal formers have been combined with acetazolamide (ACZ) via solvent drop grinding in acetone, acetonitrile, and water. The screening experiments provided co-crystals with 4-hydroxybenzoic acid (4HBA) and nicotinamide (NA) (ACZ-4HBA and ACZ-NA-H 2 O), which were identified by X-ray powder diffraction (XRPD) and further characterized by IR spectroscopy and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). Both co-crystals could be prepared also by neat grinding (NG) and reaction crystallization (RC). Single-crystal X-ray diffraction analyses allowed for an examination of the dominant hydrogen bonding patterns in the co-crystals, showing that 4HBA binds to the thiadiazole acetamide fragment of ACZ via C(N)NH···HOOC and O−H···N interactions, while NA is linked through N−H···N and N−H···O contacts. In ACZ-NA-H 2 O, the components are connected further by crystal lattice water molecules through N−H···Ow and Ow−H···N hydrogen bonds. Phase stability assays in water at physiological pH values ranging from 1.2 to 6.8 showed that for ACZ-4HBA the crystalline solid phase did not transform to ACZ within 72 h, while for ACZ-NA-H 2 O a gradual transformation occurred. Thermal treatment of ACZ-NA-H 2 O and reaction crystallization experiments in methanol and anhydrous ethanol gave the dehydrated crystalline phase ACZ-NA, which is stable at ambient conditions for at least four months but transforms to the corresponding co-crystal monohydrate when stirred with deionized water.

The combination of one dipyridyl linker [1,2-di(4-pyridyl)ethylene (DPE), 1,2-di(4-pyridyl)ethane (DPEt), or 4,4′-azopyridine (DPA)] with two molecules of arylboronate ester 1 produced dinuclear Lewis-type N→B adducts that can act as acyclic host for polycyclic aromatic hydrocarbons (PAHs) in the solid state. Nine crystalline solids of composition PAH@adduct (i.e., one PAH per adduct) were obtained from solutions containing a single PAH. On the basis of the single-crystal X-ray diffraction analysis of the compound ANT@A1 (ANT = anthracene; A1 = adduct being composed of DPE and two boronate esters 1), the PAH inclusion selectivity is related to a size-fitting adaptation to an octaedral-shaped pocket assembled by CH-π interactions between fragments of the diamine and the arylboronate ester 1. The resulting reversible organic clathrates can perform "catch and release" cycles of PAHs such as pyrene and can sequester selectively PAHs from mixtures in solution.T he molecular recognition of polycyclic aromatic hydrocarbons (PAHs) is a challenging issue given the variety of sizes, shapes, and properties of these widespread materials. 1 PAHs are among the most intensively studied pollutants in the environmental analysis of air, water, food, and solid-waste samples. Methods for quantitative separation and detection of PAHs often rely on traditional chromatographic and solventextraction protocols. 2 A well-established supramolecular approach to bind PAHs in solution consists of the use of polycationic macrocycles and cages derived from extended viologens, which are assembled covalently 3 or through metal coordination. 4 The association constants of these host−guest complexes in water and polar solvents range between 10 1 and 10 6 M −1 , and a significant number of X-ray crystal structures of such complexes has been reported. Yet these elegant supramolecular receptors were made in multistep synthetic procedures 3 or involved costly transition metals. 4 Thus, it is still a demanding task to develop simple methods to selectively detect PAHs, and also to be able to recover them quantitatively as a single (or multiple) PAH from mixtures in solution. 1,2 In the past decade, various research groups have comprehensively explored the interaction of aromatic amines with boronate esters and boroxines to provide a broad variety of discrete and polymeric materials, such as macrocycles, 5 nanostructures, 6 coordination polymers, 7 and gels. 8 Hence, supramolecular assembly based on dative N→B interactions is recognized as a useful strategy for the generation of complex systems, and given its thermodynamic stability (−11 to −38 kJmol −1 ) 6,7 and kinetic lability in polar coordinating solvents, the central N→B binding motif can be compared to a typical noncovalent interaction. The potential of this approach is well exemplified by the prismatic organic cages assembled via N→B bonds that were able to encapsulate triphenylene or coronene in the solid state. 6c These previous reports have also evidenced that simple arylmonoboronate esters ...