5-Meth­oxy-2,2-dimethyl-6-[(2E)-2-methyl­but-2-eno­yl]-10-phenyl-2H,8H-pyrano[2,3-f]chromen-8-one (calophyllolide)

The title compound, C26H24O5, was isolated from calophyllum inophyllum seeds. In the mol­ecule, the phenyl and 2-methyl­but-2-enoyl groups are almost orthogonal to the chromene fragment [C—C—C—C torsion angles = 81.4 (3) and −90.1 (2)°, respectively]. In the crystal packing, centrosymmetrically related mol­ecules are linked by C—H⋯O contacts into dimers, which are connected via further C—H⋯O inter­actions into a double chain along [010]

(3S,4R)-4-(4-Fluoro­phen­yl)-3-(hydroxy­meth­yl)piperidinium chloride1

The title compound, C12H17FNO+·Cl−, is a degradation impurity of paroxetine hydro­chloride hemihydrate (PAXIL), an anti­depressant belonging to the group of drugs called selective serotonin reuptake inhibitors (SSRIs). Similar to the paroxetine hydro­chloride salt with protonation having taken place on the basic piperidine ring, the degradation impurity also exists as the hydro­chloride salt. The cyclic six-membered piperidinium ring adopts a chair conformation with the hydroxy­methyl and 4-fluoro­phenyl groups in the equatorial positions. The ions form a tape along the b axis through charge-assisted N+—H⋯Cl− hydrogen bonds; these tapes are connected by O—H⋯Cl− hydrogen bonds along the a axis

Equivalence of NH<SUB>4</SUB><SUP>+</SUP>, NH<SUB>2</SUB>NH<SUB>3</SUB><SUP>+</SUP>, and OHNH<SUB>3</SUB><SUP>+</SUP> in directing the noncentrosymmetric diamondoid network of O-H&#183;&#183;&#183;O<SUP>-</SUP> hydrogen bonds in dihydrogen cyclohexane tricarboxylate

The assembly of hexagonal and diamond network architectures from functionalized tectons of trigonal and tetrahedral symmetry, respectively, is an important activity in crystal engineering. We report a novel supramolecular transformation for the synthesis of diamond network structures from the trigonal molecule, 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H3CTA). Crystal structures of some salts of the trigonal anion, H2CTA-, with tetrahedral counterions is analyzed in H2CTA-&#183;NH4+ 1, H2CTA-&#183;MeNH3+ 2, H2CTA-&#183;EtNH3+ 3, H2CTA-&#183;NH2NH3+ 4, and H2CTA-&#183;OHNH3+ 5. The trigonal anion functions as a tetrahedral self-complementary node in the presence of NH4+ counterion (salt 1) via two COOH donors and COO- as a double hydrogen-bond acceptor. The triply interpenetrated diamondoid network of O-H&#183;&#183;&#183;O- hydrogen bonds in 1 is reproduced in isostructural 3D nets of 4 and 5 by substituting NH4+ by NH2NH3+ and OHNH3+ (&#951; = 0.025, 0.027). The SHG activity of noncentrosymmetric diamondoid solids 1, 4, and 5 (space group Cc) is comparable to that of the nonlinear optical (NLO) material potassium dihydrogen phosphate (KDP) (0.3&#215;urea). However, salts 2 and 3 (space groups P21/c and P) have hexagonal and square grid layers of H2CTA- anions because the ammonium cation in these structures is devoid of the fourth strong hydrogen-bond donor group to extend crystal growth to the 3D diamond network. Thus, RNH3+ counterions may be used to control the anionic network of the H2CTA- molecule based on a tetrahedral node in 1, 4, and 5, a trigonal node in 2, and a square node in 3. The function of cyclohexane tricarboxylate as a four-connected node, shown for the first time in a trigonal molecule, is in contrast to the usual role of the trimesate anion as a three-connected node in molecular complexes

Molecular complexes of homologous alkanedicarboxylic acids with isonicotinamide: x-ray crystal structures, hydrogen bond synthons, and melting point alternation

Crystallization of &#945;,&#969;-alkanedicarboxylic acids (HOOC-(CH2)n-2-COOH, n = 2-6) with isonicotinamide (IN) is carried out in 1:2 and 1:1 stoichiometry. Five cocrystals of (diacid)&#183;(IN)2 composition (diacid = oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) are characterized by X-ray diffraction at 153(2) K. Tapes of acid-pyridine O-H&#183;&#183;&#183;N and amide-amide N-H&#183;&#183;&#183;O hydrogen bond synthons stabilize these five crystal structures as predicted by the hierarchic model: the best donor (COOH) and best acceptor group (pyridine N) hydrogen bond as acid-pyridine and the second best donor-acceptor group (CONH2) aggregates as an amide dimer. Glutaric acid and adipic acid cocrystallize in 1:1 stoichiometry also, (diacid)&#183;(IN), with acid-pyridine and acid-amide hydrogen bonds. Synthon energy calculations (&#916;Esynthon, RHF/6-31G) explain the observed hydrogen bond preferences in 1:2 (five examples) and 1:1 (two examples) cocrystals. The acid-pyridine hydrogen bond is favored over the acid-amide dimer for strong carboxylic acids because the difference between &#916;Eacid-pyridine and &#916;Eacid-amide (-2.21 kcal mol-1) is greater than the difference for weak acids (-0.77 kcal mol-1), which cocrystallize with both of these hydrogen bond synthons. We suggest &#916;Esynthon as a semiquantitative parameter to rank hydrogen bond preferences and better understand supramolecular organization in the multifunctional acid-IN system. Melting point alternation in five homologous (diacid)&#183;(IN)2 cocrystals is correlated with changes in crystal density and packing fraction

Recurrence of carboxylic acid-pyridine supramolecular synthon in the crystal structures of some pyrazinecarboxylic acids

X-ray crystal structures of pyrazinic acid 1 and isomeric methylpyrazine carboxylic acids 2-4 are analyzed to examine the occurrence of carboxylic acid-pyridine supramolecular synthon V in these heterocyclic acids. Synthon V, assembled by (carboxyl)O-H···N(pyridine) and (pyridine)C-H···O(carbonyl) hydrogen bonds, controls self-assembly in the crystal structures of pyridine and pyrazine monocarboxylic acids. The recurrence of acid-pyridine heterodimer V compared to the more common acid-acid homodimer I in the crystal structures of pyridine and pyrazine monocarboxylic acids is explained by energy computations in the RHF 6-31G basis set. Both the O-H···N and the C-H···O hydrogen bonds in synthon V result from activated acidic donor and basic acceptor atoms in 1-4. Pyrazine 2,3- and 2,5-dicarboxylic acids 10 and 11 crystallize as dihydrates with a (carboxyl)O-H···O(water) hydrogen bond in synthon VII, a recurring pattern in the diacid structures. In summary, the carboxylic acid group forms an O-H···N hydrogen bond in pyrazine monocarboxylic acids and an O-H···O hydrogen bond in pyrazine dicarboxylic acids. This structural analysis correlates molecular features with supramolecular synthons in pyridine and pyrazine carboxylic acids for future crystal engineering strategies

Four-fold inclined interpenetrated and three-fold parallel interpenetrated hydrogen bond networks in 1,3,5-cyclohexanetricarboxylic acid hydrate and its molecular complex with 4,4'-bipyridine

Crystallization of 1,3,5-cyclohexanetricarboxylic acid (CTA) from EtOH affords the 1:1 hydrate, CTA&#183;H2O, with 4-fold inclined interpenetrated (6,3) hydrogen-bonded networks. Crystallization of CTA with 4,4'-bipyridine (bipy) furnishes the complex, CTA&#183;bipy&#183;H2O (2:3:1), that has 3-fold interweaving (6,3) networks with parallel interpenetration. The striking similarity of these hydrogen bond networks to those found in the crystal structure of trimesic acid and its complex with bipy suggests that such interpenetrated networks may be engineered using retrosynthetic strategies

1-[(4S)-4-Benzyl-2-thioxo-1,3-thiazolidin-3-yl]propan-1-oneILS Publication No. ILS-MCO-0904.

The analysis of the title chiral auxiliary compound, C13H15NOS2, has enabled the determination of the absolute configuration at the benzyl-bearing ring C atom as S. In the crystal structure, molecules aggregate into helical chains along the b axis via C&amp;#8212;H...O contacts