6,7-Diphenyl-5-thia-7-aza-spiro-[2.6]nonan-8-one 5,5-dioxide.

The racemic mixture of the title compound, C19H19NO3S, crystallizes in space group P with two homochiral mol-ecules in each asymmetric unit. The seven-membered ring in both mol-ecules is in a pucker-chair conformation. The extended structure exhibits C-H⋯O hydrogen bonds, of which two connect crystallographically independent mol-ecules to generate a chain propagating along the b-axis direction. One C-H grouping of the cyclo-propyl ring is in close contact with the phenyl ring of the neighboring independent mol-ecule in C-H⋯π type inter-actions with carbon atom-ring-centroid distances of 3.544 (5) and 3.596 (4) Å. Other inter-actions are of the parallel-reciprocal type, with the chiral carbon atom of one mol-ecule donating a proton to an oxygen atom of the sulfone group of a symmetry-related mol-ecule and vice-versa. Symmetry-related mol-ecular pairs also exhibit T-type inter-actions between aromatic rings with inter-planar angles of 74.2 (2) and 69.2 (2)° and inter-centroid distances of 4.965 (4) and 5.114 (4) Å.

Bis(tetra-butyl-ammonium) tetra-chlorido-manganate(II) di-chloro-methane disolvate.

The title compound, (C16H36N)2[MnCl4]·2CH2Cl2, is an ionic organic-inorganic hybride compound consisting of a tetra-butyl-ammonium cation and a tetra-chlorido-manganate(II) anion in a 2:1 stoichiometric ratio. The cation contains a central nitro-gen atom bonded to four n-butyl groups in a tetra-hedral arrangement, while the anion contains a central MnII atom tetra-hedrally coordinated by four chlorido ligands. It co-crystallized with two equivalents of di-chloro-methane solvent, CH2Cl2, to give the following empirical formula: [(C4H9)4N]2[MnCl4]·(CH2Cl2)2. The crystal structure is mainly stabilized by Coulombic inter-actions.

Crystal structures of three newly synthesized flavanone hydrazones.

The crystal structures of racemic mixtures of three new flavanone-hydrazones in the centrosymmetric space group (P ), are reported. The structures of (±,E)-N'-[5,7-dihy-droxy-2-(4-hy-droxy-phen-yl)chroman-4-yl-idene]-2-(naphthalen-1-yl)acetohydrazide ethyl acetate monosolvate, C27H22N2O5·C4H8O2, and of (±,E)-N'-[5,7-dihy-droxy-2-(4-hy-droxy-phen-yl)chroman-4-yl-idene]-4-hy-droxy-benzo-hydra-zide ethanol monosolvate, C22H18N2O6·C2H5OH, both exhibit an intra-molecular O-H⋯N and multiple inter-molecular O-H⋯O and C-H⋯O-type hydro-gen bonds. The third structure, that of (±,E)-N'-(6-methoxy-2-phenyl-chroman-4-yl-idene)-2-(naphthalen-1-yl-oxy)acetohydrazide, C28H24N2O4, has only one inter-molecular N-H⋯O-type hydrogen bond. In each of the three cases, the crystal packings are stabilized by π-π stacking inter-actions between various aromatic components of symmetry-related mol-ecules. The chiral carbon atom of the substituted chromane ring system in each case is puckered away from rest of the ring system.

Crystal structures of the sulfones of 2,3-diphenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one and 2,3-diphenyl-2,3-di-hydro-4H-pyrido[3,2-e][1,3]thia-zin-4-one.

The title sulfones, 2,3-diphenyl-2,3-di-hydro-4H-1,3-benzo-thia-zine-1,1,4-trione, C20H15NO3S, and 2,3-diphenyl-2,3-di-hydro-4H-pyrido[3,2-e][1,3]thia-zine-1,1,4-trione, C19H14N2O3S, crystallize in space group P21/n with two mol-ecules in each of the asymmetric units and have almost identical unit cells and extended structures. In both structures, the thia-zine rings exhibit a screw-boat pucker. The inter-molecular inter-actions observed are C-H⋯O-type hydrogen bonds and parallel partial π-π stacking between the fused aromatic rings (benzo- or pyrido-) of the core of the mol-ecules within each asymmetric unit, and also connecting to mol-ecules with translational periodicity in the a-axis direction in what can be described as columns (two per asymmetric unit) of stacked mol-ecules with alternating chirality. The pendant phenyl groups of both mol-ecules do not participate in aromatic ring inter-actions.

Crystal structures of rac-2,3-diphenyl-2,3,5,6-tetra-hydro-4H-1,3-thia-zine-1,1,4-trione and N-[(2S,5R)-1,1,4-trioxo-2,3-diphenyl-1,3-thia-zinan-5-yl]acet-amide.

The syntheses and crystal structures of two thia-zinone compounds, namely, rac-2,3-diphenyl-2,3,5,6-tetra-hydro-4H-1,3-thia-zine-1,1,4-trione, C16H15NO3S, in its racemic form, and N-[(2S,5R)-1,1,4-trioxo-2,3-diphenyl-1,3-thia-zinan-5-yl]acet-amide, C18H18N2O4S, in an enanti-opure form, are reported. The thia-zine rings in the two structures differ in their puckering, as a half-chair in the first and a boat pucker in the second. The extended structures for both compounds have only C-H⋯O-type inter-actions between symmetry-related mol-ecules, and exhibit no π-π stacking inter-actions in spite of each having two phenyl rings.

Stabilization of Dinuclear Rhodium and Iridium Clusters on Layered Titanate and Niobate Supports.

Atomically dispersed organometallic clusters can provide well-defined nuclearity of active sites for both fundamental studies as well as new regimes of activity and selectivity in chemical transformations. More recently, dinuclear clusters adsorbed onto solid surfaces have shown novel catalytic properties resulting from the synergistic effect of two metal centers to anchor different reactant species. Difficulty in synthesizing, stabilizing, and characterizing isolated atoms and clusters without agglomeration challenges allocating catalytic performance to atomic structure. Here, we explore the stability of dinuclear rhodium and iridium clusters adsorbed onto layered titanate and niobate supports using molecular precursors. Both systems maintain their nuclearity when characterized using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Statistical analysis of HAADF-STEM images revealed that rhodium and iridium dimers had mean cluster-to-cluster distances very similar to what is expected from a random distribution of atoms over a large area, indicating that they are dispersed without aggregation. The stability of dinuclear rhodium clusters supported on titanate nanosheets was also investigated by X-ray absorption fine structure (EXAFS), DRIFTS, and first-principles calculations. Both X-ray absorption spectroscopy and HAADF-STEM simulations, guided by density functional theory (DFT)-optimized structure models, suggested that rhodium dimers adsorb onto the nanosheets in an end-on binding mode that is stable up to 100 °C under reducing conditions. This study highlights that crystalline nanosheets derived from layered metal oxides can be used as model supports to selectively stabilize dinuclear clusters, which could have implications for heterogeneous catalysis.

Crystal structure of racemic (R/S,E)-2-(4-hy-droxy-phen-yl)-4-(2-phenyl-hydrazin-1-yl-idene)chromane-5,7-diol ethanol monosolvate.

The crystal structure of racemic (R/S,E)-2-(4-hy-droxy-phen-yl)-4-(2-phenyl-hydrazin-1-yl-idene)chromane-5,7-diol ethanol monosolvate, C21H18N2O4·C2H6O, in a centrosymmetric lattice is reported. The two racemates occupy the same position in the asymmetric unit - a disordered mixed enanti-omeric structure. Hydrogen bonds of the type O-H⋯C(π) in addition to typical C-H⋯O, O-H⋯O and O-H⋯N are identified. A positional disorder is seen in the solvent mol-ecule (ethanol) as well. The phenyl-hydrazone group is nearly coplanar with the chromane ring system [dihedral angle = 15.5 (1)°], while the the 4-hy-droxy-phenyl ring is perpendicular [dihedral angle = 87.2 (1)°] to the chromane. The pyran ring has an envelope pucker [Q = 0.363 (3) Å, θ = 57.6 (3)°; and for the enanti-omer: Q = 0.364 (3) Å, θ = 127.4 (4)°].

Synthesis and crystal structure of racemic (R*,R*)-2,2'-(1,4-phenyl-ene)bis-(3-phenyl-2,3,5,6-tetra-hydro-4H-1,3-thia-zin-4-one).

In the racemic title compound, C26H24N2O2S2, one of the thia-zine rings shows a twisted boat conformation (Q = 0.743 Å, θ = 92.1°) and the other a half-chair puckering (Q = 0.669 Å, θ = 54.3°). The terminal phenyl rings are almost parallel to each other [dihedral angle 21.71 (10)°]. Both of these rings are orthogonal to the central phenyl ring, subtending a dihedral angle of about 78° in each case. The extended structure is consolidated by C-H⋯O and C-H⋯S hydrogen bonds as well as aromatic ring inter-actions of parallel-displaced and T-type. The mol-ecule has approximate C2 local symmetry but this is not carried over to its three-dimensional structure or the inter-molecular inter-actions.

T3P-Promoted Synthesis of a Series of 2-Aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones and Their Activity against the Kinetoplastid Parasite Trypanosoma brucei.

A series of fourteen 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-phenyl-C-aryl imines with thionicotinic acid, two difficult substrates. The reactions were operationally simple, did not require specialized equipment or anhydrous solvents, could be performed as either two or three component reactions, and gave moderate-good yields as high as 63%. This provides ready access to N-phenyl compounds in this family, which have been generally difficult to prepare. As part of the study, the first crystal structure of neutral thionicotinic acid is also reported, and showed the molecule to be in the form of the thione tautomer. Additionally, the synthesized compounds were tested against T. brucei, the causative agent of Human African Sleeping Sickness. Screening at 50 µM concentration showed that five of the compounds strongly inhibited growth and killed parasites.

Maize unstable factor for orange1 is essential for endosperm development and carbohydrate accumulation.

Maize (Zea mays L.) Ufo1-1 is a spontaneous dominant mutation of the unstable factor for orange1 (ufo1). We recently cloned ufo1, which is a Poaceae-specific gene highly expressed during seed development in maize. Here, we have characterized Ufo1-1 and a loss-of-function Ds insertion allele (ufo1-Dsg) to decipher the role of ufo1 in maize. We found that both ufo1 mutant alleles impact sugars and hormones, and have defects in the basal endosperm transfer layer (BETL) and adjacent cell types. The Ufo1-1 BETL had reduced cell elongation and cell wall ingrowth, resulting in cuboidal shaped transfer cells. In contrast, the ufo1-Dsg BETL cells showed a reduced overall size with abnormal wall ingrowth. Expression analysis identified the impact of ufo1 on several genes essential for BETL development. The overexpression of Ufo1-1 in various tissues leads to ectopic phenotypes, including abnormal cell organization and stomata subsidiary cell defects. Interestingly, pericarp and leaf transcriptomes also showed that as compared with wild type, Ufo1-1 had ectopic expression of endosperm development-specific genes. This study shows that Ufo1-1 impacts the expression patterns of a wide range of genes involved in various developmental processes.

Hydrothermal Synthesis and Structure of a Dinuclear Molybdenum(III) Hydroxy Squarate with a Mo-Mo Bond.

The reaction of molybdenum(II) and chromium(II) acetates with squaric acid in degassed and deionized water under hydrothermal conditions at 150 °C is described. The products have been formulated as M2(µ-OH)2(µ-C4O4)2(H2O)4·2H2O, where M = Cr (1) and Mo (2), based on combustion elemental analysis, infrared spectroscopy, magic angle spinning (MAS) solid-state carbon-13 nuclear magnetic resonance (NMR), and single-crystal X-ray diffraction. The edge-shared bioctahedral structures involve doubly bridging hydroxide ligands and µ-squarate ligands. The chromium compound lacks a direct metal-metal-bonding interaction, while in contrast the molybdenum compound contains a Mo-Mo bond [2.491(2) Å]. The nature of the Mo-Mo-bonding interaction is compared with that of other similar d3-d3 dimers.

A General Strategy to Enhance Donor-Acceptor Molecules Using Solvent-Excluding Substituents.

While organic donor-acceptor (D-A) molecules are widely employed in multiple areas, the application of more D-A molecules could be limited because of an inherent polarity sensitivity that inhibits photochemical processes. Presented here is a facile chemical modification to attenuate solvent-dependent mechanisms of excited-state quenching through addition of a ß-carbonyl-based polar substituent. The results reveal a mechanism wherein the ß-carbonyl substituent creates a structural buffer between the donor and the surrounding solvent. Through computational and experimental analyses, it is demonstrated that the ß-carbonyl simultaneously attenuates two distinct solvent-dependent quenching mechanisms. Using the ß-carbonyl substituent, improvements in the photophysical properties of commonly used D-A fluorophores and their enhanced performance in biological imaging are shown.

Crystal structures of two solvated 2-aryl-3-phenyl-2,3-di-hydro-4H-pyrido[3,2-e][1,3]thia-zin-4-ones.

The synthesis and crystal structures of 2-(4-fluoro-phen-yl)-3-phenyl-2,3-di-hydro-4H-pyrido[3,2-e][1,3]thia-zin-4-one toluene hemisolvate (1), C19H13FN2OS·0.5C7H8, and 2-(4-nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-pyrido[3,2-e][1,3]thia-zin-4-one iso-propanol 0.25-solvate 0.0625-hydrate (2), C19H13N3O3S·0.25C3H7O·0.0625H2O, are reported. Both are racemic mixtures (centrosymmetric crystal structures) of the individual com-pounds and incorporate solvent mol-ecules in their structures. Compound 2 has four thia-zine mol-ecules in the asymmetric unit. All the thia-zine rings in this study show an envelope pucker, with the C atom bearing the substituted phenyl ring displaced from the other atoms. The phenyl and aryl rings in each of the mol-ecules are roughly orthogonal to each other, with dihedral angles of about 75°. The extended structures of 1 and 2 are consolidated by C-H⋯O and C-H⋯N(π), as well as T-type (C-H⋯π) inter-actions. Parallel aromatic ring inter-actions (π-π stacking) are observed only in 2.

Crystal structures of three hexakis-(fluoroar-yloxy)cyclo-triphosphazenes.

The syntheses and crystal structures of three cyclo-triphosphazenes, all with fluorinated ar-yloxy side groups that generate different steric characteristics, viz. hexa-kis-(penta-fluoro-phen-oxy)cyclo-triphosphazene, N3P3(OC6F5)6, 1, hexa-kis-[4-(tri-fluoro-methyl)-phen-oxy]cyclo-triphosphazene, N3P3[OC6H4(CF3)]6, 2 and hexa-kis-[3,5-bis(-tri-fluoro-methyl)-phen-oxy]cyclo-triphosphazene, N3P3[OC6H3(CF3)2]6 3, are reported. Specifically, each phospho-rus atom bears either two penta-fluoro-phen-oxy, 4-tri-fluoro-methyl-phen-oxy, or 3,5-tri-fluoro-methyl-phen-oxy groups. The central six-membered phosphazene rings display envelope pucker conformations in each case, albeit to varying degrees. The maximum displacement of the 'flap atom' from the plane through the other ring atoms [0.308 (5) Å] is seen in 1, in a mol-ecule that is devoid of hydrogen atoms and which exhibits a 'wind-swept' look with all the aromatic rings displaced in the same direction. In 3 an intra-molecular C-H(aromatic)⋯F inter-action is observed. All the -CF3 groups in 2 and 3 exhibit positional disorder over two rotated orientations in close to statistical ratios. The extended structures of 2 and 3 are consolidated by C-H⋯F inter-actions of two kinds: (a) linear chains, and (b) cyclic between mol-ecules related by inversion centers. In both 1 and 3, one of the six substituted phenyl rings has a parallel-displaced aromatic π-π stacking inter-action with its respective symmetry mate with slippage values of 2.2 Šin 1 and 1.0 Šin 3. None of the structures reported here have solvent voids that could lead to clathrate formation.

Crystal structures of two isomeric 2-aryl-3-phenyl-1,3-thia-zepan-4-ones.

The crystal of 6-(3-nitro-phen-yl)-7-phenyl-5-thia-7-aza-spiro-[2.6]nonan-8-one (1), C19H18N2O3S, has monoclinic (P21/n) symmetry while that of its isomer 6-(4-nitro-phen-yl)-7-phenyl-5-thia-7-aza-spiro-[2.6]nonan-8-one (2), has ortho-rhom-bic (Pca21) symmetry: compound 1 has two mol-ecules, A and B, in the asymmetric unit while 2 has one. In all three mol-ecules, the seven-membered thia-zepan ring exhibits a chair conformation with Q2 and Q3 values (Å) of 0.521 (3), 0.735 (3) and 0.485 (3), 0.749 (3) in 1 and 0.517 (5), 0.699 (5) in 2. In each structure, the phenyl rings attached to adjacent atoms of the thia-zepan ring have inter-planar angles ranging between 41 and 47°. Except for the nitro groups, the three mol-ecules have similar conformations when overlayed in pairs. Both crystal structures are consolidated by C-H⋯O hydrogen bonds.

Crystal structure of a 1:1 adduct of tri-phenyl-tin chloride with 3-cyclo-hexhyl-2-phenyl-1,3-thia-zolidin-4-one.

In the centrosymmetric (racemic) title compound, chlorido-(3-cyclo-hexhyl-2-phenyl-1,3-thia-zolidin-4-one-κO)tri-phenyl-tin(IV), [Sn(C6H5)3Cl(C15H19NOS)], the tin(IV) atom exhibits a trigonal-bipyramidal coordination geometry with the three phenyl groups in equatorial positions and the chloride anion and ligand oxygen atom present at axial sites [O-Sn-Cl = 175.07 (14)°]. The thia-zolidinone ring of the ligand adopts an envelope conformation with the S atom as the flap. The dihedral angles between the heterocycle ring plane (all atoms) are 44.3 (9)° with respect to the pendant C-phenyl plane and 34.3 (11)° to the N-cyclo-hexyl ring (all atoms). The C-phenyl and N-cyclo-hexyl ring are close to orthogonal to each other, with a dihedral angle of 81.1 (4)° between them. In the crystal, mol-ecules are linked by weak C-H⋯Cl hydrogen bonds to generate [001] chains.

Crystal structures of two 1,3-thia-zolidin-4-one derivatives featuring sulfide and sulfone functional groups.

The crystal structures of two closely related compounds, 1-cyclo-hexyl-2-(2-nitro-phen-yl)-1,3-thia-zolidin-4-one, C15H18N2O3S, (1) and 1-cyclo-hexyl-2-(2-nitro-phen-yl)-1,3-thia-zolidin-4-one 1,1-dioxide, C15H18N2O5S, (2), are presented. These compounds are comprised of three types of rings: thia-zolidinone, nitrophenyl and cyclo-hexyl. In both structures, the rings are close to mutually perpendicular, with inter-planar dihedral angles greater than 80° in each case. The thia-zol-idinone rings in both structures exhibit envelope puckering with the S atom as flap and the cyclo-hexyl rings are in their expected chair conformations. The two structures superpose fairly well, except for the orientation of the nitro groups with respect to their host phenyl ring, with a difference of about 10° between 1 and 2. The extended structure of 1 has two kinds of weak C-H⋯O inter-actions, giving rise to a closed ring formation involving three symmetry-related mol-ecules. Structure 2 has four C-H⋯O inter-actions, two of which are exclusively between symmetry-related thia-zolidinone dioxide moieties and have a parallel 'give-and-take-fashion' counterpart. In the other two inter-actions, the nitrophenyl ring and the cyclo-hexane ring each offer an H atom to the two O atoms on the sulfone group. Additionally, a C-H⋯π inter-action between a C-H group of the cyclo-hexane ring and the nitrophenyl ring of an adjacent mol-ecule helps to consolidate the structure.

Crystal structure of meso-3,3'-(1,4-phenyl-ene)bis-(2-phenyl-2,3,5,6-tetra-hydro-4H-1,3-thia-zin-4-one).

The crystal structure of the title compound - meso-C26H24N2O2S2 with two stereocenters - has half the mol-ecule in the asymmetric unit with the other half generated by a crystallographic center of inversion. The thia-zine ring is in a conformation that is between half-chair and envelope [θ = 52.51 (17)°]. The phenyl ring on the 2-carbon atom of the thia-zine ring is pseudo-axial. The central phenyl ring of the mol-ecule is close to orthogonal to the phenyl rings on either side with an angle of 76.85 (11)° between those planes. In the crystal, pairwise, weak C-H⋯O hydrogen bonds between the central phenyl ring and the oxygen atoms of neighboring mol-ecules result in continuous strips propagating along the a-axis direction. Hydro-phobic inter-actions of the C-H⋯π type are also observed.

Crystal structures of two thia-zolidinone derivatives bearing a tri-chloro-methyl substituent at the 2-position.

The title compounds 2-tri-chloro-methyl-3-phenyl-1,3-thia-zolidin-4-one (C10H8Cl3NOS), 1 and 3-(4-chloro-phen-yl)-2-tri-chloro-methyl-1,3-thia-zolidin-4-one (C10H7Cl4NOS) 2, are structurally related with one atom substitution difference in the para position of the benzene ring. In both structures, the thia-zolidinone ring adopts an envelope conformation with the S atom as the flap. The dihedral angles between the rings [48.72 (11) in 1 and 48.42 (9)° in 2] are very similar and the mol-ecules are almost superimposable. In both crystal structures, C-H⋯O 'head-to-tail' inter-actions between the chiral carbon atoms and the thia-zolidinone oxygen atoms result in infinite monochiral chains along the direction of the shortest unit-cell parameter, namely a in 1 and b in 2. C-H⋯π inter-actions between the thia-zolidinone carbon atom at the 4-position and the phenyl ring of the neighboring enanti-omer also help to stabilize the packing in each case, although the crystals are not isostructural.

Modulation of Fluorescent Protein Chromophores To Detect Protein Aggregation with Turn-On Fluorescence.

We present a fluorogenic method to visualize misfolding and aggregation of a specific protein-of-interest in live cells using structurally modulated fluorescent protein chromophores. Combining photophysical analysis, X-ray crystallography, and theoretical calculation, we show that fluorescence is triggered by inhibition of twisted-intramolecular charge transfer of these fluorophores in the rigid microenvironment of viscous solvent or protein aggregates. Bioorthogonal conjugation of the fluorophore to Halo-tag fused protein-of-interests allows for fluorogenic detection of both misfolded and aggregated species in live cells. Unlike other methods, our method is capable of detecting previously invisible misfolded soluble proteins. This work provides the first application of fluorescent protein chromophores to detect protein conformational collapse in live cells.