(E)-4-Phenyl­butan-2-one oxime

In the title compound, C10H13NO, the C—C—C—C torsion angle formed between the benzene ring and the butan-2-one oxime unit is 73.7 (2)°, with the latter lying above the plane through the benzene ring. In the crystal, inter­molecular O—H⋯N hydrogen bonds link pairs of mol­ecules into dimers, forming R 2 2(6) ring motifs which are stacked along the a axis

3′-(4-Meth­oxy­phen­yl)-4′-phenyl-3H,4′H-spiro­[1-benzothio­phene-2,5′-isoxazol]-3-one

In the title compound, C23H17NO3S, the thio­phene and isoxazole rings each have an envelope conformation with the spiro C atom linking them forming the flap of the envelope in each case. The dihedral angle between the mean planes of the benzothio­phene ring and isoxazole rings is 81.35 (7)°. In the crystal, an inter­molecular C—H⋯O hydrogen bond links the mol­ecules into a chain running parallel to the a axis

8-[(1E)-1-(2-Aminophenyl­iminio)eth­yl]-2-oxo-2H-chromen-7-olate

The title Schiff base, C17H14N2O3, exists as an NH tautomer with the H atom of the phenol group transferred to the imine N atom. The iminium H atom is involved in a strong intra­molecular N+—H⋯O− hydrogen bond to the phenolate O atom, forming an S(6) motif. In the crystal structure, N—H⋯O hydrogen bonds form a C(9) chain parallel to [100] and a C(11) chain parallel to [010], while C—H⋯O hydrogen bonds form a C(11) chain parallel to [010]. The combination of N—H⋯O and C—H⋯O hydrogen bonds generates R 4 3(30) rings parallel to the ab plan

7-[(3,5-Di-tert-butyl-2-hy­droxy­benzyl­idene)amino]-4-methyl-2H-chromen-2-one

The title compound, C25H29NO3, is a Schiff base derivative of coumarin 120. There are two structurally similar but crystallographically independent mol­ecules in the asymmetric unit. Both mol­ecules exist in E configurations with respect to the C=N double bonds. The dihedral angles between the coumarin and 3,5-di-tert-butyl-2-hy­droxy­benzyl­idene ring planes are 4.62 (7) and 14.62 (7)° for the two mol­ecules. Intra­molecular O—H⋯N hydrogen bonding involving the O—H groups and the azomethine N atoms generate S(6) rings. In the crystal structure, independent mol­ecules are linked by C—H⋯π inter­actions, with groups of four mol­ecules stacked along the c axis

4-Thioxo-3,5-dithia-1,7-hepta­nedioic acid

The complete molecule of the title compound, C5H6O4S3, is generated by crystallographic twofold symmetry with the C=S group lying on the rotation axis. The molecules are linked through weak hydrogen-bond contacts by glide-plane operations to form R 2 2(20) rings and ladder-like C(4) chains along the c axis

(4-Meth­oxy­phen­yl)methanaminium chloride

In the crystal structure of the title salt, C8H12NO+·Cl−, the methoxy group of the cation is co-planar with the phenylene moiety with an r.m.s. deviation from the mean plane of only 0.005 Å. The ammonium N atom deviates from this plane by 1.403 (1) Å. In the crystal, the (4-meth­oxy­phen­yl)methan­aminium cations and chloride anions are linked by N—H⋯Cl and C—H⋯O hydrogen bonds, resulting in an open framework architecture with hydrogen-bonded ammonium groups and chloride anions located in layers parallel to (011), separated by more hydrophobic layers with interdigitating anisole groups

N′-(Di-2-pyridylmethyl­ene)benzo­hydrazide

In the title Schiff base, C18H14N4O, the amido –NH– unit is connected to one of the two pyridyl N atoms at an N(—H)⋯N distance of 2.624 (2) Å. The mol­ecular packing features an inter­molecular C—H⋯N R 2 2(6) hydrogen-bonding ring motif

On The Power of Tree Projections: Structural Tractability of Enumerating CSP Solutions

The problem of deciding whether CSP instances admit solutions has been deeply studied in the literature, and several structural tractability results have been derived so far. However, constraint satisfaction comes in practice as a computation problem where the focus is either on finding one solution, or on enumerating all solutions, possibly projected to some given set of output variables. The paper investigates the structural tractability of the problem of enumerating (possibly projected) solutions, where tractability means here computable with polynomial delay (WPD), since in general exponentially many solutions may be computed. A general framework based on the notion of tree projection of hypergraphs is considered, which generalizes all known decomposition methods. Tractability results have been obtained both for classes of structures where output variables are part of their specification, and for classes of structures where computability WPD must be ensured for any possible set of output variables. These results are shown to be tight, by exhibiting dichotomies for classes of structures having bounded arity and where the tree decomposition method is considered

Impact of PNKP mutations associated with microcephaly, seizures and developmental delay on enzyme activity and DNA strand break repair

Microcephaly with early-onset, intractable seizures and developmental delay (MCSZ) is a hereditary disease caused by mutations in polynucleotide kinase/phosphatase (PNKP), a DNA strand break repair protein with DNA 5'-kinase and DNA 3'-phosphatase activity. To investigate the molecular basis of this disease, we examined the impact of MCSZ mutations on PNKP activity in vitro and in cells. Three of the four mutations currently associated with MCSZ greatly reduce or ablate DNA kinase activity of recombinant PNKP at 30°C (L176F, T424Gfs48X and exon15Δfs4X), but only one of these mutations reduces DNA phosphatase activity under the same conditions (L176F). The fourth mutation (E326K) has little impact on either DNA kinase or DNA phosphatase activity at 30°C, but is less stable than the wild-type enzyme at physiological temperature. Critically, all of the MCSZ mutations identified to date result in ∼10-fold reduced cellular levels of PNKP protein, and reduced rates of chromosomal DNA strand break repair. Together, these data suggest that all four known MCSZ mutations reduce the cellular stability and level of PNKP protein, with three mutations likely ablating cellular DNA 5'-kinase activity and all of the mutations greatly reducing cellular DNA 3'-phosphatase activity

7,7′,8,8′-Tetra­meth­oxy-4,4′-dimethyl-3,5′-bichromene-2,2′-dione

In the title mol­ecule, C24H22O8, the mean planes of the two coumarin units are inclined to each other at a dihedral angle of 79.93 (3)°. The attached meth­oxy groups form torsion angles of 7.65 (19) and 78.36 (14)° with respect to one coumarin unit, and angles of 9.01 (16) and 99.08 (11)° with respect to the other coumarin unit. In the crystal structure, weak inter­molecular C—H⋯O hydrogen bonds connect pairs of mol­ecules to form dimers, generating R 2 2(16) and R 2 2(18) rings; the dimers are linked by further weak inter­molecular C—H⋯O hydrogen bonds, forming extended chains. Additional stabil­ization is provided by weak C—H⋯π inter­actions