The title compound, C 25 H 28 N 4 O 2 , crystallizes in space group P 1 with Z = 4. The two independent molecules are related by the approximate translation ( x + 1, y + 1, z ), but differ in the orientation of the phenyl substituent. Crystals are non-merohedrally twinned by a 180° rotation about c *. In the modified chromene ring systems, the two formal double bonds are the shortest C—C bonds. The oxo ring displays a flattened boat conformation, whereas the other ring is approximately a flattened envelope, with the CMe 2 C atom out of the plane. The molecules are connected by classical N—H...N pyrazole hydrogen bonds to form a ribbon of alternating independent molecules parallel to [110]. The ribbons are joined by weak C pyrazole —H...N nitrile hydrogen bonds to form a layer structure parallel to the ab plane in the region z ≃ 3/4.

The title com-pound, C25H28N4O2, crystallizes in space group P1 with Z = 4. The two independent mol-ecules are related by the approximate translation (x + 1, y + 1, z), but differ in the orientation of the phenyl substituent. Crystals are non-merohedrally twinned by a 180° rotation about c*. In the modified chromene ring systems, the two formal double bonds are the shortest C-C bonds. The oxo ring displays a flattened boat conformation, whereas the other ring is approximately a flattened envelope, with the CMe2 C atom out of the plane. The mol-ecules are connected by classical N-H⋯Npyrazole hy-dro-gen bonds to form a ribbon of alternating independent mol-ecules parallel to [110]. The ribbons are joined by weak Cpyrazole-H⋯Nnitrile hy-dro-gen bonds to form a layer structure parallel to the ab plane in the region z ≃ 3/4.

The synthesis of twelve new tricyclic flavonoids, with a bromine substituent at the ortho, meta or para position of the B ring, from the corresponding flavanones is described. Four structures were unambiguously proven by X-ray analysis. An SAR study of the antibacterial properties against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Klebsiella pneumoniae was performed and revealed compound- and strain-dependent activity, with 5h showing the most promising broad-spectrum antibacterial profile, while 5f, 5i and 5j also exhibited strong activity against selected strains. Cytotoxicity assays showed high cell viability (>90%) at 0.001 mg mL-1 for all compounds, indicating dose-dependent cytotoxicity. These findings highlight 5h as a promising candidate for further investigation.

In the title compound, (Z)-3-{2-[(Z)-11H-indeno-[1,2-b]quinoxalin-11-yl-idene]hydrazin-yl}-N-phenyl-but-2-enamide monohydrate, C25H19N5O·H2O, the configurations around the C=N and C=C double bonds adjacent to the hydrazinyl moiety are both Z. Except for the phenyl group, the mol-ecule is almost planar, promoted by the three-centre intra-molecular Nhydrazin-yl-H⋯(Ocarbon-yl, Nquinoxaline) hydrogen bond. The water mol-ecule participates in three hydrogen bonds, as donor towards Ocarbon-yl (within the asymmetric unit) and the other Nquinoxaline (via an inversion operator) and as acceptor from the amide N-H group (via a b-glide operator). The hydrogen bonds combine to form a layer structure parallel to the ab plane.

The molecule of the title compound, C21H14N2O3S2, is approximately planar except for the terminal carbon atom of the ethyl group. The planarity is promoted by two short intramolecular S...O=C contacts and one intramolecular ‘weak' C—H...O=C hydrogen bond. The two thiazole rings show some appreciable differences in bond lengths and angles, associated with their different annelation patterns. The molecular packing involves one ‘weak' hydrogen bond of the type C—H...O=C, which links the molecules in zigzag chains via a 21 screw axis along [010]. Additionally, ‘stacked' pairs of molecules, necessarily with parallel ring systems, are related by an inversion operator, and two π contacts C—H...π and C=O...π are observed.

The title compound (E)-2-(benzo[d]thia-zol-2-yl)-N'-(1-(4-bromo-phen-yl)ethyl-idene)acetohydrazide, C17H14BrN3OS, crystallizes in space group P21/c with Z = 4. The configuration across the formal N=C double bond at the hydrazide moiety is E; the atom sequence C-C-C(= O)-N-N=C-(bromo-phen-yl) is very approximately planar (r.m.s. deviation 0.17 Å, when all carbon atoms of the bromo-phenyl group are included), being synperiplanar around the C(=O)-N bond and anti-periplanar (choosing the appropriate final atom CAr) elsewhere. The inter-planar angle to the benzo-thia-zole unit (r.m.s. deviation 0.01 Å) is 69.75 (2)°. The main packing feature is a classical inversion-symmetric dimer with hydrogen bonds of the type N-H⋯O=C. This combines with a rather long Nthia-zole⋯Br halogen bond to form a thick layer structure parallel to the bc plane.

In the title compound, (Z)-3-{2-[(Z)-11H-indeno[1,2-b]quinoxalin-11-ylidene]hydrazinyl}-N-phenylbut-2-enamide monohydrate, C25H19N5O·H2O, the configurations around the C=N and C=C double bonds adjacent to the hydrazinyl moiety are both Z. Except for the phenyl group, the molecule is almost planar, promoted by the three-centre intramolecular Nhydrazinyl—H...(Ocarbonyl, Nquinoxaline) hydrogen bond. The water molecule participates in three hydrogen bonds, as donor towards Ocarbonyl (within the asymmetric unit) and the other Nquinoxaline (via an inversion operator) and as acceptor from the amide N—H group (via a b-glide operator). The hydrogen bonds combine to form a layer structure parallel to the ab plane.

The title compound, C14H13ClN4O2S2·C2H6OS, crystallizes in space group P1 with Z = 4. Both main (‘parent') molecules are closely similar except for minor differences in the orientations of the aromatic rings. The bond angles at the nitrogen atoms of the (S)C—NH—Cguanidine moieties are very wide at ca 130°. The parent molecules display intramolecular hydrogen bonds Ph—N—H...N—S and C—N(H)—H...O=S, and both formula units involve a bifurcated hydrogen bond system from two N—H donors to the oxygen atom of a DMSO molecule; the orientation of the DMSO molecules is however appreciably different. Further classical hydrogen bonds link the residues to form a ribbon parallel to the b axis.

The two title compounds, 4a C19H19N2O3P and 4b C17H15N2O3P, are not isotypic. The tetracyclic ring systems are essentially planar. The phosphonate groups are similarly oriented. Compound 4a crystallizes in P1 with Z′ = 1; molecules are linked in inversion-symmetric pairs by classical hydrogen bonds N—H...O=P, forming rings of graph set R22(12). Compound 4b crystallizes in P21/c with Z′ = 2; the two independent molecules are linked by a hydrogen-bond system analogous to that of 4a, but the ring systems subtend an interplanar angle of 55.84 (1)°. For 4a, the hydrogen bonding combines with ring stacking in pairs to form a ribbon structure parallel to the b axis. For 4b, the classical hydrogen bonding combines with two ‘weak' hydrogen bonds C—H...O to form a layer structure parallel to the ac plane. Non-spherical atom scattering factors were employed (using the program NoSpherA2) to avoid the problem of badly fitting reflections in high-resolution data (2θmax ca 105° using Mo Kα radiation).

The first synthesis of the spirobi[benzofuran]dione core structure of the spirobiflavonoid daphnodorin C is described. The key step is the oxidative ring contraction of electron-rich benzofuro[3,2-b]chromenones by treatment with dimethyldioxirane, which afforded novel 2,3 '-spirobi[benzofuran]diones, rather than the isomeric spiroketals. The conversion probably proceeds via epoxidation, followed by Meinwald-type rearrangement with acyl migration. The starting materials were obtained by the condensation of alpha-brominated o-fluoroacetophenone and methyl salicylate derivatives. The structures of several of the novel spiro compounds were confirmed by X-ray analysis.

Silver N-heterocyclic carbene (NHC) complexes are known to form biscarbene species from monocarbene analogs in protic polar solvents. However, the effect of the respective species of silver NHC complexes on their biological activity against bacteria or cancer cells has not been systematically explored, either in vitro or in vivo. The direct and simple conversion of monocarbene silver N-heterocyclic carbene (NHC) halide complexes (NHC)AgX, (X=Cl, Br) 1 a/b-5 a/b to their biscarbene analogues (NHC)2AgX 1 c/d-5 c/d is reported. The biscarbenes demonstrated generally lower activity against bacteria compared to the monocarbene complexes; however, both types showed similar activity against tumor cells and a non-tumor reference cell line. Selected mono- and biscarbene complexes 3 a and 3 c showed similar strong inhibitory effects on thioredoxin reductase in vitro and in cellulo and had a similar level of metal uptake into A549 cells. The subsequent evaluation of their effects in vivo revealed relatively low toxicity and high antitumoral efficacy of both selected complexes in mice. The biscarbene silver organometallic 3 c showed the most pronounced reduction of tumor growth in animals. The results indicate that both (NHC)AgX and (NHC)2AgX complexes could trigger their anticancer activity as biscarbene complexes, making this the preferred form for future anticancer metallodrug development.

In the title compound, C27H23ClN6O3·C3H7NO, much of the molecule is approximately planar, excluding the pyridinic ring, which is almost perpendicular to this plane, and the sp3 atoms of the modified xanthene system. The diazene group is E-configured. In the extended structure, two hydrogen bonds of the type N—H...O and one N—H...Cl combine to form a layer structure parallel to (111). The solvent is severely disordered and this necessitated the use of SQUEEZE for a reliable refinement.

In the structure of the title compound, C19H13ClN4OS, the four atoms of the pyridinic ring that are not fused with the thiazole, including the sp3 C atom, lie significantly outside the benzothiazole plane. A short intramolecular S...O contact of 2.5992 (4) Å is observed. The amide NH2 group is planar, whereas the amine NH2 group is pyramidalized. The three-dimensional packing involves two interconnected layer structures. The first, parallel to the bc plane, involves three classical hydrogen bonds N—Hamine...O (one of two), N—Hamine...Cl and one N—Hamide ...Ncyano; the second, parallel to the ab plane, involves two hydrogen bonds, N—Hamide...O and the second N—Hamine...O, together with the short and linear contact Ncyano...Cl—C, which may be regarded as a halogen bond.

trans-Dibromidobis(3,5-lutidine)gold(III) tribromide, [AuBr2(C7H9N)2](Br3) or [(3,5-Lut)2AuBr2](Br3), 1, polymorph a, crystallizes in the space group P1 with Z = 1. The gold atom and the central bromine of the tribromide ion lie on inversion centres. Polymorph b crystallizes in C2221 with Z = 4. The gold atom, the nitrogen atoms and the ring atoms at the 4-position of the lutidine ligands, and the central bromine of the tribromide ion all lie on twofold axes. The formula units of 1a and 1b are closely similar (including the relative orientations of anion and cation). 3,5-Lutidinium tetrabromidoaurate(III), (C7H10N)[AuBr4] or (3,5-LutH)[AuBr4], 2, crystallizes as a new polymorph in P32 with Z = 3. Bis(3,5-lutidinium) tetrabromidoaurate(III) bromide, (C7H10N)2[AuBr4]Br or (3,5-LutH)2[AuBr4]Br, 3, polymorph a, crystallizes in C2/c with Z = 4. The gold atom lies on an inversion centre and the bromide ion on a twofold axis. Polymorph b crystallizes in P21/c with Z = 8 (Z′ = 2) and all atoms on general positions. Tris(3,5-lutidinium) bis[tetrabromidoaurate(III)] bromide, (C7H10N)3[AuBr4]2Br or (3,5-LutH)3[AuBr4]2Br, 4, crystallizes in P1 with Z = 2. One gold atom lies on a general position and two on inversion centres. The main interest centres on the crystal packing patterns. In structure 1a, a short Au...Branion contact, presumably a ‘coinage bond', combines with a ‘weak' hydrogen bond Hortho...Branion and a further contact Brcation...Branion to form a layer structure parallel to the ac plane. Polymorph 1b shows similar Au...Branion and Hortho...Branion contacts, resulting in a chain of residues parallel to the c axis. The most striking feature of the previous polymorph of compound 2 was a topologically square, but distorted, network of tetrabromidoaurate ions. The packing of the new polymorph of 2 involves three-centre hydrogen bonds Br...H...Br′, an axial coinage bond Au...Br, and two Br...Br contacts, one of which completes an unusual AuBr2 three-centre system. The extended packing shows three one-dimensional arrays of residues parallel to the threefold axis, linked by one Br...Br contact to form a layer. In polymorph a of compound 3, the packing is based on a dimeric unit with twofold symmetry, centred on the free bromide ion, which is involved in two hydrogen bonds and two Br...Br interactions. The dimers are connected via further Br...Br contacts to form a zigzag chain parallel to the c axis. Polymorph b displays two hydrogen-bonded (3,5-LutH...)2Br groupings to the two free bromides, together with two tetrabromidoaurate ions linked by a Br...Br contact; the second anion is also connected to a free bromide. The residues thus linked form a broad band parallel to the c axis. There are also infinite stacks of planar residues with the repeating sequence (...[AuBr4]−...lutidinium...lutidinium...) parallel to the a axis. In compound 4, all three cations are hydrogen bonded to the free bromide. The anions at two gold centres (Au1/Au2) form a chain parallel to the a axis via Br...Br contacts. The anions at Au3 combine with the free bromide to form a chain of Au2Br4 rings parallel to the a axis, via Au...Br and Br...Br contacts, and these chains link with those at Au1 via another Br...Br contact to form a broad ribbon of residues. The ribbons are in turn linked by a Br...π contact.

In the structure of the title compound, C5H12N+·C19H10N3O2S-·C19H11N3O2S, the central pyridinic rings are approximately coplanar to the benzo-thia-zole moieties. The phenyl groups are appreciably angled to the central rings [inter-planar angles of 57.30 (3)° for the anion and 79.01 (4)° for the neutral mol-ecule]. Bond lengths and angles correspond to considerable delocalization of the π bonding, especially for the anion; all four C=O bond lengths are similar [1.2365 (13)-1.2591 (13) Å]. The two main residues display different configurations about the formally double C-C bonds between the benzo-thia-zole and pyridinic ring systems; the neutral mol-ecule is E, facilitating an intra-molecular N-H⋯O hydrogen bond, but the anion is Z, allowing a short intra-molecular S⋯O contact of 2.5794 (10) Å. Within the asymmetric unit, the piperidinium cation is hydrogen bonded to an oxygen atom of the anion; the anion and the neutral mol-ecule are connected by two N-H⋯O hydrogen bonds, forming a ring of graph-set R 2 2(8). Asymmetric units are linked to form inversion-symmetric dimers by an Hcation⋯Oanion hydrogen bond. These are further linked by a C-H⋯O hydrogen bond to form a broad ribbon of residues parallel to the a axis.

In the structure of the title compound, C17H25NO9S2, the bond lengths in the C—S—C moiety are almost equal at 1.7959 (8) and 1.7877 (9) Å, with a shorter formally double C—S bond of 1.6698 (9) Å at the other sulfur atom. The eight-atom sequence O3—C3—C2—C1—S—C—N—C (using standard sugar numbering) shows an extended conformation. The packing involves ‘weak’ hydrogen bonds, whereby the three shortest C—H...O contacts combine to form layers of molecules parallel to the ab plane.

In the structure of the title compound, C 5 H 12 N + ·C 19 H 10 N 3 O 2 S − ·C 19 H 11 N 3 O 2 S, the central pyridinic rings are approximately coplanar to the benzothiazole moieties. The phenyl groups are appreciably angled to the central rings [interplanar angles of 57.30 (3)° for the anion and 79.01 (4)° for the neutral molecule]. Bond lengths and angles correspond to considerable delocalization of the π bonding, especially for the anion; all four C=O bond lengths are similar [1.2365 (13)–1.2591 (13) Å]. The two main residues display different configurations about the formally double C—C bonds between the benzothiazole and pyridinic ring systems; the neutral molecule is E , facilitating an intramolecular N—H...O hydrogen bond, but the anion is Z , allowing a short intramolecular S...O contact of 2.5794 (10) Å. Within the asymmetric unit, the piperidinium cation is hydrogen bonded to an oxygen atom of the anion; the anion and the neutral molecule are connected by two N—H...O hydrogen bonds, forming a ring of graph-set R 2 2 (8). Asymmetric units are linked to form inversion-symmetric dimers by an H cation ...O anion hydrogen bond. These are further linked by a C—H...O hydrogen bond to form a broad ribbon of residues parallel to the a axis.

The structure of O-ethyl N-phenylthiocarbamate, C9H11NOS (2), has been redetermined, confirming the results obtained in three earlier structure determinations. The higher data quality provided by modern diffractomers has enabled a reliable analysis (absent from the earlier reports) of the hydrogen bonding. However, conventional refinement of the structure of 2 was unsatisfactory because of the large number of extremely badly-fitting reflections, leading to many checkCIF `ALERT A' messages that might be detrimental to ease of publication. A refinement using nonspherical scattering factors effectively eliminated this problem. There are three independent molecules of 2 in the asymmetric unit; two are directly connected by two N-H...S hydrogen bonds, forming a dimer with the well-known R22(8) motif. The other molecule forms a topologically identical but inversion-symmetric dimer. Each type of dimer occupies a different region parallel to the ac plane (molecule 1, y ≃ 0; molecules 2 and 3, y ≃ 1/3 and 2/3). All three molecules lie in planes parallel to (031). The title compound is effectively isotypic to 1-ethyl-3-phenylthiourea (another known structure for which the hydrogen bonding was not analysed) because its EtNH group, like the EtO group of 2, is not involved in hydrogen bonding.

During the development of an optimized procedure for the synthesis of 2,3-dihydro-1,1,2,2,3,3-hexamethyl-1H-indene significant amounts of 5-tert-butyl-2,3-dihydro-1,1,2,2,3,3-hexamethyl-1H-indene were formed, along with 5-tert-hexyl-2,3-dihydro-1,1,2,2,3,3-hexamethyl-1H-indene under certain conditions. The structures of 5-tert-hexyl-2,3-dihydro-1,1,2,2,3,3-hexamethyl-1H-indene and 5-tert-butyl-2,3-dihydro-1,1,2,2,3,3-hexamethyl-1H-indene were established by spectroscopic means and confirmed by X-ray single-crystal structure determinations. The mechanism for the formation of 5-tert-butyl-2,3-dihydro-1,1,2,2,3,3-hexamethyl-1H-indene is discussed.

By combining the well-known motifs of BODIPY dyes and cycloparaphenylenes, novel nanohoop derivatives were accessible via established procedures. Absorption and emission spectra showed overall bathochromic shifts, and their photophysical behavior can be tuned by introducing steric demand to modulate the conjugation throughout the system. 19F NMR spectra underline distinct differences in the conformations, and (TD)DFT calculations provide a deeper insight into the geometry, photophysical behavior, and influence of steric demand.