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The genus Sphaerostilbella comprises fungi that colonize basidiomata of wood-inhabiting fungi, including important forest pathogens. Studies of fermentation cultures of an isolate (TFC201724) collected on the foothills of Himalayas, and closely related to S. broomeana isolates from Europe, led to the identification of a new cyclic octapeptide along with two closely related analogues (1–3) and four dioxopiperazines (4–7). The structure of the lead compound, broomeanamide A (1), was assigned mainly by analysis of 2D NMR and HRESIMS data. The structure consisted of one unit each of N-MeVal, Ala, N-MePhe, Pro, Val, and Ile and two N-MeLeu units. The amino acid sequence was determined on the basis of 2D NMR and HRESIMSMS data. NMR and HRMS data revealed that the other two new peptides have the same amino acid composition except that the Ile unit was replaced with Val in one instance (2) and the N-MeVal unit was replaced with Val in the other (3). The absolute configuration of 1 was assigned by analysis of the acid hydrolysate by application of Marfey’s method using both C18 and C3 bonded-phase columns. Broomeanamide A (1) showed antifungal activity against Cryptococcus neoformans and Candida albicans, with MIC values of 8.0 and 64 μg/mL, respectively.

Here we report the synthesis, characterization, and hydrolytic stability of water-soluble Pt(ii) complexes containing a triaminoborane-bridged diphosphoramidite ligand that can be fluorinated using simple fluoride salts.

We describe hydrogen bonds (i.e., N+–H⋯N) in combination with cation⋯π interactions to enable a cascade-like [2 + 2] photodimerization of 4-stilbazole in a salt cocrystal. A four-component crystal assembly is composed of photoactive pyridinium ion pair 4-stilbzH+ (4-stilbz = trans-1-(4-pyridyl)-2-(phenyl)ethylene) and photostable molecule pair 4-stilbz. UV irradiation gives rctt-1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane (4-pyr-ph-cb) in quantitative yield. An intermediate structure 2(4-stilbz)·(4-pyr-ph-cb)2H+ is isolated that undergoes a partial single-crystal-to-single-crystal transformation. The single-crystal X-ray data provides a snapshot of movements in the salt cocrystal in the course of the photodimerization.

A method to rapidly diversify the molecules formed in organic crystals is introduced, with aryl nitriles playing a novel dual role as both hydrogen-bond acceptors and modifiable organic groups. The discovery of coexisting supramolecular synthons in the same crystal is also described. The general concept is demonstrated by using a bis(aryl nitrile) alkene that undergoes a hydrogen-bond-directed intermolecular [2+2] photodimerization to form a tetra(aryl nitrile)cyclobutane. The product is readily converted by click reactivity to a tetra(aryl tetrazole) and by hydrolysis to a tetra(aryl carboxylic acid). The integration of aryl nitriles into solid-state reactions opens broad avenues to post-modify products formed in crystalline solids for rapid diversification.

Triaminoborane-bridged diphosphorus ligands called TBDPhos can undergo cooperative ligand-centered reactions at the 1,8,10,9-triazaboradecalin (TBD) backbone while bound to metals, but the factors ...

We report on B←N coordination to support a single-crystal-to-single-crystal reaction in the solid state. A [2 + 2] photodimerization is achieved with face-to-face π-stacks of monotopic B←N adducts ...

We report supramolecular repurposing of emtricitabine (FTC, trade name: Emtriva®), a blockbuster FDA-approved anti-HIV agent. FTC is revealed to act as a hydrogen-bonded cleft for bipyridine recognition. The supramolecular repurposing is realized by the generation of four cocrystals through liquid-assisted grinding. The clefts comprise discrete three-component assemblies sustained by a combination of hydrogen bonds and π⋯π interactions.

Cocrystallizations of diboronic acids [1,3-benzenediboronic acid (1,3-bdba), 1,4-benzenediboronic acid (1,4-bdba) and 4,4'-biphenyldiboronic acid (4,4'-bphdba)] and bipyridines [1,2-bis(4-pyridyl)ethylene (bpe) and 1,2-bis(4-pyridyl)ethane (bpeta)] generated the hydrogen-bonded 1 : 2 cocrystals [(1,4-bdba)(bpe)

Photoirradiation of a binary cocrystal composed of two different cyclic dienes generates a highly-symmetric cubane-like tetraacid cage regioselectively and in quantitative yield. The cage forms by a double [2+2] photodimerization of one of the diene cocrystal components. The second diene while photostable in the cocrystal reacts in a double [2+2] photodimerization as a pure form quantitatively to form a tetramethyl cubane-like cage. The stereochemistry of the cage is structurally authenticated.

The 1:1 caffeine (CAF) and 3-nitrobenzoic acid (NBA) cocrystal (CAF:NBA) displays polymorphism. Each polymorph shares the same docking synthon that connects individual CAF and NBA molecules within the asymmetric unit; however, the extended intermolecular interactions are significantly different between the two polymorphic modifications. These alternative interaction topologies translate to distinct structural motifs, mechanical properties, and compaction performance. To assist our molecular interpretation of the structure-mechanics-performance relationships for these cocrystal polymorphs, we combine powder Brillouin light scattering (p-BLS) to determine the mechanical properties with energy frameworks calculations to identify potentially available slip systems that may facilitate plastic deformation. The previously reported Form 1 for CAF:NBA adopts a 2D-layered crystal structure with a conventional 3.4 Å layer-to-layer separation distance. For Form 2, a columnar structure of 1D-tapes is displayed with CAF:NBA dimers running parallel to the (110) crystallographic direction. Consistent with the layered crystal structure, the shear modulus for Form 1 is significantly reduced relative to Form 2, and moreover, our p-BLS spectra for Form 1 clearly display the presence of low-velocity shear modes, which support the expectation of a low-energy slip system available for facile plastic deformation. Our energy frameworks calculations confirm that Form 1 displays a favorable slip system for plastic deformation. Combining our experimental and computational data indicates that the structural organization in Form 1 of CAF:NBA improves the compressibility and plasticity of the material, and from our tabletability studies, each of these contributions confers superior tableting performance to that of Form 1. Overall, mechanical and energy framework data permit a clear interpretation of the functional performance of polymorphic solids. This could serve as a robust screening approach for early pharmaceutical solid form selection and development.

In an ongoing effort to study the environmental fate of endocrine-active steroid hormones, we report the formation of phenolic rearrangement products (3 and 4) with a novel 6,5,8,5-ring system following aqueous photolysis of dienogest (1) and methyldienolone (2). The structures were established by analysis of 2D NMR and HRMS data, and that of 3 was confirmed by X-ray diffraction analysis. These photoproducts exhibit progestogenic and androgenic activity, albeit with less potency than their parent compounds.

The ability of 2,4,6-trihalophenols (3X-phOH) (where X = F, Cl, or Br) to enable reactivity of 1,2-bis(4-pyridyl)ethylene (bpe) in the solid state via cocrystallization is reported. The trihalophen...

A structural study of two-dimensional inverted metal–organic frameworks demonstrates that the interior cavities of the framework structures can be systematically modified by changing the organic anion of a Cu(II)-paddlewheel unit. Changing the anion allows modifications to the shapes and sizes of the cavities in a series of isoreticular frameworks. The construction of the frameworks is based on the application of a tetrafunctional organic cyclobutane ligand synthesized in the organic solid state.

The halogen-bond (X-bond) donors 1,3- and 1,4-diiodotetrafluorobenzene (1,3-di-I-tFb and 1,4-di-I-tFb, respectively) form cocrystals with trans-1,2-bis(2-pyridyl)ethylene (2,2&prime, bpe) assembled by N&middot, &middot, I X-bonds. In each cocrystal, 2(1,3-di-I-tFb)&middot, 2(2,2&prime, bpe) and (1,4-di-I-tFb)&middot, (2,2&prime, bpe), the donor molecules support the C=C bonds of 2,2&prime, bpe to undergo an intermolecular [2+2] photodimerization. UV irradiation of each cocrystal resulted in stereospecific and quantitative conversion of 2,2&prime, bpe to rctt-tetrakis(2-pyridyl)cyclobutane (2,2&prime, tpcb). In each case, the reactivity occurs via face-to-face &pi, stacked columns wherein nearest-neighbor pairs of 2,2&prime, bpe molecules lie sandwiched between X-bond donor molecules. Nearest-neighbor C=C bonds are stacked criss-crossed in both cocrystals. The reactivity was ascribed to the olefins undergoing pedal-like motion in the solid state. The stereochemistry of 2,2&prime, tpcb is confirmed in cocrystals 2(1,3-di-I-tFb)&middot, tpcb) and (1,4-di-I-tFb)&middot, tpcb).

We report the discovery of three polymorphs of the very recently FDA-approved boron-containing active pharmaceutical ingredient, Crisaborole. Crisaborole displays polymorphism based on the syn (Form I) and anti (Form II) conformations of the hydroxyl group of the oxaborole ring as shown by single-crystal X-ray analysis. Forms I and II were discovered based on the availability from two different commercial suppliers, while Form III was obtained upon heating of Form I or II. A cocrystal based on 4,4′-bipyridine was also obtained.

The acoustic frequency distributions, mechanical moduli, and crystal structures for theophylline (THY) and three cocrystals are combined to illustrate how supramolecular organization and interaction topology contribute to the compaction performance of molecular solids. A novel solid form of THY, a cocrystal with 4-fluoro-3-nitrobenzoic acid (FNBA), is reported. This material adopts a 2d-layered structure and has superior tabletability relative to THY. The improved plasticity for THY–FNBA was further corroborated by Heckel analysis with THY–FNBA displaying a reduced yield pressure (Py) relative to theophylline. The performance of THY–FNBA was further compared to a structurally similar theophylline cocrystal with acetaminophen (THY–APAP). Despite structural similarity, their relative compaction performance was distinct. Powder Brillouin light scattering (p-BLS) was used as an experimental measure of the interaction topologies of these materials, and through this approach, the interlayer interaction strength...

Auxarthrones A–E (1–5), five new phenalenones, and two new naturally occurring cyclic tetrapeptides, auxarthrides A (7) and B (8), were obtained from three different solvent extracts of cultures of the coprophilous fungus Auxarthron pseudauxarthron. Auxarthrones C (3) and E (5) possess an unusual 7a,8-dihydrocyclopenta[a]phenalene-7,9-dione ring system that has not been previously observed in natural products. Formation of 1–5 was found to be dependent on the solvent used for culture extraction. The structures of these new compounds were elucidated primarily by analysis of NMR and MS data. Auxarthrone A (1) was obtained as a mixture of chromatographically inseparable racemic diastereomers (1a and 1b) that cocrystallized, enabling confirmation of their structures by X-ray crystallography. The absolute configurations of 7 and 8 were assigned by analysis of their acid hydrolysates using Marfey’s method. Compound 1 displayed moderate antifungal activity against Cryptococcus neoformans and Candida albicans, but did not affect human cancer cell lines.

Strong hydrogen-bonding interactions are predictably leveraged for local molecular docking; however, weak intermolecular interactions are being increasingly recognized as pivotal governors of extended, supramolecular assembly. In this report, a series of nitrobenzoic acids (NBA) – m-nitrobenzoic acid (3-NBA), p-nitrobenzoic acid (4-NBA), 4-methyl-3-NBA (Me-NBA), 4-chloro-3-NBA (Cl-NBA) and 4-bromo-3-NBA (Br-NBA) – are utilized to systematically adjust weak C–H⋯O (nitro) and C–H⋯O (carboxyl) bonding interactions and discriminate their influence on the crystal structure, aggregate elasticity and compaction performance. The expected carboxylic acid dimer persists across the entire NBA series; however, alternative organization of C–H⋯O interactions yields distinct 1-d tapes. The acoustic frequency distributions obtained from powder Brillouin light scattering (BLS) spectra provide supportive interpretation of the strength and anisotropy of the reorganized intermolecular interactions. Aggregate Young's moduli displayed a narrow range from 13.5 GPa for Br-NBA to 9.8 GPa for 3-NBA. However, the maximum longitudinal moduli (Mmax), calculated from the high-frequency cutoff, revealed significant differences in the strength of intermolecular interactions along the 1-d tapes. For 3-NBA, the extended organization of several co-linear C–H⋯O (nitro) interactions yielded an Mmax of 42.0 GPa, while the remaining NBA materials displayed an Mmax near 25 GPa. From powder compaction studies, the tabletability rank order was observed as: 3-NBA > 4-NBA > Me-NBA ≈ Br-NBA ≈ Cl-NBA; however, none of the materials achieved a tensile strength greater than 1 MPa. Overall, even minor redistribution of weak intermolecular interactions significantly modifies supramolecular assembly in NBA and detailing the specific contribution of these weak forces is required for substantive structure–performance correlation.

The ability of organoboronic acids to direct intermolecular [2 + 2] photodimerizations in the solid state is identified. The reactivity of 1,2-bis(4-pyridyl)ethylene (bpe) within cocrystals of discrete hydrogen-bonded molecular assemblies generates rctt-tetrakis(4-pyridyl)cyclobutane (tpcb) stereoselectively and in up to quantitative yield. Dry grinding of the boronic acids and excess bpe reveal the acids to function as supramolecular catalysts.

A single-crystal-to-single-crystal (SCSC) photodimerization is achieved using Au(I) coordination and aurophilic interactions. The rigid Au2(dppbz)(CF3COO)2 precursor (dppbz = 1,2-bis(diphenylphosph...

Photoirradiation of the titled compounds perfluoro- cis -1,2-dimethyl-butadienyl benzenes ( 1 ), which were prepared in several steps from perfluorovinyl bromide, results in the formation of the corresponding novel naphthalene derivatives and 1,4-dihydronaphthalenes. Isolated 1,1,2-trifluoro-3,4-bis(trifluoromethyl)-1,4-dihydronaphthalene ( 3a ) could be converted into 1,2-bistrifluoromethyl-3,4-difluoronaphthalene ( 2a ) by base treatment (DABCO); however, 3a did not lead to 2a by photoreaction, suggesting 3a was not a possible photochemical precursor. Competitive photoreaction studies suggest that varying the substituent on benzene ring (e.g. methyl or trifluoromethyl) does not significantly affect the reaction rate. Presently, this reaction mechanism is not yet clearly understood.

Co-crystallization of a symmetrical azo bipyridine with isosteric resorcinols affords isostructural co-crystals that exhibit linear thermal expansion along each axis. The thermal expansions involve interplay between intra-layer halogen and hydrogen bonds.

Seven new polyketide metabolites (disseminins A-E, 1-5, and spiciferones D and E, 7 and 8) were obtained from cultures of a fungicolous isolate of Pestalotiopsis disseminata (NRRL 62562), together with a related compound (6) previously known only as a semisynthetic product. Structures were determined mainly by analysis of HRMS and NMR data. Biogenetically related compounds 1 and 2 possess uncommon bis-tetrahydrofuran and dioxabicyclo[3.2.1]octane ring systems, respectively. X-ray crystallographic analysis of the p-bromobenzoate derivative of 1 confirmed the structure and enabled assignment of its absolute configuration.

A combination of metal-organic self-assembly and reversible imine formation is used to achieve an organic synthesis via the solid state. Imine bond formation is employed to install a pyridyl to the alkene trans-cinnamaldehyde while Ag(I) ions are used in a second step to assemble the pyridyl-functionalized alkene into a geometry in the solid state for an intermolecular [2 + 2] photodimerization. The alkene undergoes the cycloaddition reaction via a 1D coordination polymer to generate a pyridyl-functionalized cyclobutane stereoselectively and in quantitative yield. Removal of the pyridyl group affords the aldehyde-functionalized cyclobutane α-truxilaldehyde.

Zinc centers in pseudo-tetrahedral geometry are widely found in biology, often with three histidine ligands from protein. The trispyrazolylborate “scorpionate” ligand is used as a model for this tris(histidine) motif, and spectroscopically active CoII is often used as a substitute for spectroscopically silent ZnII. In this work, four pseudo-tetrahedral scorpionate complexes with the formula (Tpt-Bu,Tn)CoL, where Tpt-Bu,Tn = hydrotris(3-tert-butyl, 5–2′-thienyl-pyrazol-1-yl)borate anion and L = Cl−, N3−, NCO−, or NCS−, were studied using variable-temperature, variable-field magnetic circular dichroism (VTVH MCD) spectroscopy. The major goal was to determine the axial and rhombic zero field splitting (ZFS) parameters (D and E, respectively) of these S = 3/2 systems and compare these ZFS parameters to those determined previously by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy on the same (L = Cl− and NCS−) or closely related complexes. Additionally, HFEPR studies were undertaken here on the complexes with L = N3−, NCO−. Crystal structures for these two complexes are also first reported here. The values of D determined by VTVH MCD were + 12.8 and + 3.6 cm−1 for the L = Cl− and NCS- complexes, respectively. These values are in close agreement with those for the same complexes as previously determined by HFEPR. The values of D determined by VTVH MCD were + 3.0 and + 6.6 cm−1 for the L = N3− and NCO- complexes, respectively. These values were not as close to those determined by HFEPR in the present study, which are 4.2 cm−1 ≤ |D| ≤ 5.6 cm−1 in Tpt-Bu,TnCoN3, and 8.3 cm−1 ≤ |D| ≤ 11.0 cm−1 in Tpt-Bu,TnCoNCO. The bands in MCD spectra of these complexes were assigned in C3v symmetry and a complete ligand-field analysis of the MCD data was made using the Angular Overlap Model (AOM), which is compared to previous results.

B←N coordination supports a [2+2] photodimerization in the solid state. The bond is defined by an orthogonal interaction between stilbazole and a phenylboronic ester to enable a stereocontrolled and rapid photoreaction. The cyclobutane photoproduct affords a novel diboron bis-tweezer adduct that is used to separate a mixture of benzene and thiophene upon crystallization.

A correlation between Young's modulus, as determined by using nanoindentation atomic force microscopy (AFM), and atomic polarizability is observed for members of a series of cocrystals based on systematic changes to one cocrystal component. Time domain spectroscopy over terahertz frequencies (THz-TDS) is used for the first time to directly measure the polarizability of macro- and nanosized organic solids. Cocrystals of both macro- and nanodimensions with highly polarizable atoms result in softer solids and correspondingly higher polarizabilities.

Ten N-halophenylpyridinium salts (halogen = Br or I) with chloride (and in one case iodide) counterions have been prepared and structurally characterized in order to examine the degree of solid state halogen bonding exhibited in these systems. N-Halophenylpyridinium salts are easily synthesized from existing pyridines, and the cationic pyridinium group is expected to increase the halogen bond donor ability of attached halophenyl moieties. Halide anions functioning as halogen bond acceptors facilitate formation of charge-assisted halogen bonds. All five substrates featuring iodophenyl or diiodophenyl substituents displayed the expected halogen bonding interactions. In several cases halide ion acceptors were also engaged in complementary hydrogen bonding interactions with C–H groups of pyridinium rings and O–H groups of water solvates. Halogen bond donors containing a diiodophenyl group formed either an extended network or discrete supramolecular macrocyclic constructs through ArI···Cl–···IAr bridging inter...

Thermal expansion involves a response of a material to an external stimulus that typically involves an increase in a crystallographic axis (positive thermal expansion (PTE)), although shrinking with applied heat (negative thermal expansion (NTE)) is known in rarer cases. Here, we demonstrate a means to achieve dynamic molecular motion and thermal expansions in organic solids via co-crystallizations. One co-crystal component is known to exhibit dynamic behaviour in the solid state while the second, when varied systematically, affords co-crystals with linear thermal expansion coefficients that range from colossal to nearly zero. Two co-crystals exhibit rare NTE. We expect the approach to guide the design of molecular solids that enable predesigned motion related to thermal expansion processes.

Solid state reduction of NbCl5, with excess NaCl, by Ga2Cl4 under lower-temperature (175°) kinetic control yields a brown powder from which the green, incomplete cubane cluster compound [Nb3(µ3-Cl)(µ-Cl)3(NCCH3)9]4+, with GaCl4 − anions, can be extracted by acetonitrile in 51 % isolated yield. This seven valence electron discrete cluster is a moderately-soluble coordination complex of the known, seven electron, extended structure (Nb3Cl8)x. The solid state structure consists of a triangular cluster with one face-capping µ3-Cl, three edge-bridging µ-Cl ligands on the opposite face, and three terminal N-bonded CH3CN ligands per Nb. The average Nb–Nb, Nb–(µ3-Cl), and Nb–(µ-Cl) distances for one of the four independent cluster cores in the unit cell are 2.811[1] A, 2.438[9] A, and 2.427[3] A, respectively, and the average Nb–(µ-Cl)–Nb angle is 70.8[1]°. These values are compared to those of other discrete triniobium clusters and triniobium chloride extended structures with the Nb3(µ3-X)(µ-X)3XnL9−n incomplete metallacubane structure.

An intramolecular [2 + 2] photocycloaddition is achieved in the organic solid state via self-assembly of Ag(I) ions and an endo-ditopic bipyridine. The cations aide to organize carbon-carbon double (C═C) bonds attached to the bipyridine for the cycloaddition reaction. The C═C bonds react regioselectively and quantitatively to afford a photoproduct with edge-sharing four-, five-, and six-membered rings. Our study demonstrates the first use of a metal-organic template to direct an intramolecular [2 + 2] photodimerization in the organic solid state.

We have prepared and characterized two ruthenium(II) complexes supported by phosphine-functionalized N-heterocyclic (NHC) ligands. One of the complexes (2a) underwent ortho-metalation of the N-phenyl moiety giving rise to a tridentate PCNHCC− coordinating ligand whereas 2b bears an N-mesityl group in order to prevent C–H activation of the aryl ring thereby enforcing a PCNHC bidentate binding mode. Both 2a and 2b were shown to catalyze transfer hydrogenation of ketones at 82 °C in 2-propanol in the presence of KOtBu albeit with vastly different catalytic activities. Catalytic transfer hydrogenation by 2b was shown to proceed at room temperature and in air using unpurified 2-propanol as solvent and hydrogen donor. Time studies revealed unique kinetic profiles for the two precatalysts; this may shed light on the difference in their catalytic activities.

Ta(hpp)Cl4, Ta(hpp)2Cl3, and (η-C5Me4R)Ta(hpp)Cl3 (R = Me, Et; hpp = anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, hppH) are readily formed in good to excellent yields by addition of (hpp)SiMe3 to TaCl5, Ta(hpp)Cl4, or (η-C5Me4R)TaCl4, respectively, in dichloromethane. Ta(hpp)Cl4 in solution exhibits three CH2 multiplets in the proton NMR spectrum, consistent with a mirror plane that bisects the hpp ligand. The six-coordinate, yellow Ta(hpp)Cl4 possesses a distorted octahedral solid-state structure with chelating hpp and Ta–N distances of 2.038(1) and 2.059(1) A. Ta(hpp)2Cl3 is fluxional in solution by proton NMR spectroscopy, with three CH2 multiplets at room temperature that split into additional multiplets at −50 °C, consistent with the six multiplets expected from the solid-state structure. In the solid state, bright yellow Ta(hpp)2Cl3 has an approximately pentagonal bipyramidal structure with both hpp chelates coordinated in the pentagonal plane. Ta–N distances are 2.114(3) and 2.110(3...

Three amino acid-derived compounds, haenamindole (1) and 2'-epi-fumiquinazolines C (2) and D (3), were isolated from cultures of a fungicolous isolate of Penicillium lanosum (MYC-1813=NRRL 66231). Compound 1 was also encountered in cultures of P. corylophilum (MYC-418=NRRL 28126). Structure elucidation of these metabolites was based mainly on high resolution mass spectrometry and NMR data analysis. Haenamindole (1) was found to be a recently reported diketopiperazine-type metabolite that incorporates an unusual β-Phe unit. Analysis of X-ray crystallographic data and the products of acid hydrolysis of 1 enabled a conclusive, slightly modified stereochemical assignment for haenamindole. Fumiquinazoline analog 2 is a new natural product, while related compound 3 has been previously reported only as a product of an in vitro enzymatic step and of a genetically engineered fungal culture. Compounds 1 and 3 showed antiinsectan activity against the fall armyworm Spodoptera frugiperda.

Four meroterpenoids [talarolutins A–D] and one known compound [purpurquinone A] were characterized from an endophytic fungal isolate of Talaromyces minioluteus (G413), which was obtained from the leaves of the medicinal plant milk thistle [Silybum marianum (L.) Gaertn. (Asteraceae)]. The structures of talarolutins A–D were determined by the analysis of various NMR and MS techniques. The relative and absolute configuration of talarolutins A was determined by X-ray diffraction analysis. A combination of NOESY data and comparisons of ECD spectra were employed to assign the relative and absolute configuration of the other analogues. Talarolutins B–D were tested for cytotoxicity against human prostate carcinoma (PC-3) cell line, antimicrobial activity, and induction of quinone reductase; no notable bioactivity was observed in any assay.

Two tetraarylethylene derivatives symmetrically functionalized at the 4, 4′, 4″, and 4 ‴ positions with either 4-pyridyl or 3-pyridyl groups were converted to their corresponding tetrapyridinium perchlorate salts upon exposure to Fe(ClO4)3·xH2O. These tetra-perchlorates were isolated as single crystals and their structures were determined by X-ray diffractometry. In both cases extensive hydrogen bonding networks were observed involving pyridinium N–H groups, perchlorate anions, and included water molecules. Additionally, both structures feature hydrophobic crystalline regions formed from stacking of tetraarylethylene cations in helical fashion. Polar pyridinium N–H groups are directed outward from these stacks into hydrophilic crystalline regions containing perchlorate anions and water molecules of hydration. Information obtained regarding the solid state structures of these functionalized tetraarylethylene derivatives should prove useful in design of more elaborate supramolecular architectures.

Two tetrapyridyl-substituted tetraphenylethylenes have been prepared via Suzuki coupling between tetrabromo tetraphenylethylene and 3- or 4-pyridine boronic acid. Both compounds exhibit aggregation-induced emission as determined by solid state fluorescence spectroscopy and solution phase fluorescence measurements performed in aqueous/organic solvent mixtures. Solution phase fluorescence was also found to be switchable as a function of pH. 3-Pyridyl-substituted tetraphenylethylene has been structurally characterized by X-ray crystallography.

A saturated dicarboxylic acid is employed to achieve a photoreactive hydrogen-bonded assembly based on a thiophene that reacts to generate a head-to-tail photoproduct. A co-crystal that exhibits both a homo- and heterosynthon in the same co-crystal based on adipic acid and the thiophene is also presented.

The chiral compounds (6aS,9S,10aR)-11,11-dimethyl-5,5-dioxo-2,3,8,9-tetrahydro-6H-6a,9-methanooxazaolo[2,3-i][2,1]benzisothiazol-10(7H)-one, C(12)H(17)NO(4)S, (1), (7aS,10S,11aR)-12,12-dimethyl-6,6-dioxo-3,4,9,10-tetrahydro-7H-7a,10-methano-2H-1,3-oxazino[2,3-i][2,1]benzisothiazol-11(8H)-one, C(13)H(19)NO(4)S, (2), (6aS,9S,10R,10aR)-11,11-dimethyl-5,5-dioxo-2,3,7,8,9,10-hexahydro-6H-6a,9-methanooxazolo[2,3-i][2,1]benzisothiazol-10-ol, C(12)H(19)NO(4)S, (3), and (7aS,10S,11R,11aR)-12,12-dimethyl-6,6-dioxo-3,4,8,9,10,11-hexahydro-7H-7a-methano-2H-[1,3]oxazino[2,3-i][2,1]benzisothiazol-11-ol, C(13)H(21)NO(4)S, (4), consist of a camphor core with a five-membered spirosultaoxazolidine or six-membered spirosultaoxazine, as both their keto and hydroxy derivatives. In each structure, the molecules are linked via hydrogen bonding to the sulfonyl O atoms, forming chains in the unit-cell b-axis direction. The chains interconnect via weak C-H...O interactions. The keto compounds have very similar packing but represent the highest melting [507-508 K for (1)] and lowest melting [457-458 K for (2)] solids.

Solid-state reduction of WCl6 with Hg followed by incomplete sublimation of mercury chlorides generated the tritungsten decachloride—mercury chloride adducts W3Cl10(Hg2Cl2)2−x(HgCl2)x. Thermal equilibration of the solid-state products followed by sublimation of HgCl2 afforded single crystals that include the mercurous chloride adduct W3Cl10(Hg2Cl2)2. Single-crystal diffractometry revealed a one-dimensional polymer of tritungsten decachloride triangular clusters with novel terminal and inter-cluster-bridging ClHgHgCl ligands. The W3 cluster core has similar metrics to that of the benzyltriethylammonium salt of W3(μ3-Cl)(μ-Cl)3Cl9 3−. W3Cl10(Hg2Cl2)2 is the first reported adduct of the binary tungsten chloride W3Cl10. The ClHgHgCl ligands are more labile that the terminal chlorine atoms of W3(μ3-Cl)(μ-Cl)3Cl9 3−. These results demonstrate diverse roles and potential utility of main group element halide by-product ligands in solid-state reductions of transition metal halides.

Hymenopsin A (1), hymenopsin B (2), and a new macrophorin analogue, 2′,3′-epoxy-13-hydroxy-4′-oxomacrophorin A (3), have been isolated from a fungicolous isolate of Hymenopsis sp. (MYC-1703; NRRL 37638). The structures and relative configurations of these compounds were assigned on the basis of 2D NMR and MS data, and the identity of 1 was confirmed by X-ray crystallographic analysis. The absolute configuration of 2 was proposed on the basis of CD analysis using both empirical and computational methods. Compounds 2 and 3 showed antibacterial activity against Staphylococcus aureus and Bacillus subtilis. Compound 3 was also active against Aspergillus flavus and Fusarium verticillioides.

Solid-state halogen bonding interactions present in four families of structurally similar tritopic haloarenes were examined in an effort to identify molecular features that promote halogen···carbonyl, halogen···halogen, and/or halogen···π interactions. The substrates used in this study all featured three haloarene substituents attached to a central 1,3,5-substituted arene ring with conformationally flexible linkers (ketone or ester groups) in order to systematically vary the polarization of the aryl halogen groups. Within each individual substrate type, however, there was found to be little correlation in the halogen bonding motifs exhibited as a function of halogen present (I, Br, and Cl). In general, the iodoarene derivatives examined exhibited a greater degree of halogen bonding interactions than the bromo and chloro analogues, and a unique bifurcated I···I/I···O═C halogen bonding synthon was identified in two substrates. Halogen bonding contacts observed in tritopic iodoarenes correlated nicely with e...

The cis-fused hexahydroxanthene system can be obtained through a cascade cyclization initiated by Lewis acid-mediated epoxide opening and terminated by reaction with a MOM-protected phenol. Only a single diastereomer of the product was obtained with stereochemistry verified by diffraction analysis. This demonstrates the viability of this approach to natural products containing the cis-fused hexahydroxanthene skeleton, and supports preparation of more complex targets through a similar strategy.

An experimentally straightforward procedure for the synthesis of structurally elaborate cyclohexadienyl ruthenium(II) complexes has been developed along the lines of the Morita−Baylis−Hillman reaction. Coordination of (cyclopentadienyl)Ru(II) fragments to N-benzyl and N-phenethyl acrylamides was found to facilitate conversion to stable cyclohexadienyl complexes via Bu3P-mediated intramolecular cyclization. An ipso cyclization was observed in all but one case, resulting in formation of five- or six-membered spirolactams at C6 positions of cyclohexadienyl ligands. Acrylamides prepared from dihydroindene and tetrahydronaphthalene precursors were suitable substrates for this transformation, affording access to novel tricyclic cyclohexadienyl complexes. One such complex was characterized by X-ray crystallography.