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The styryl and ester substituents are displaced to opposite sides of the plane through the pyridine ring while the acetyl group is rotated well out of that plane. In the crystal, inversion-related C—H⋯O hydrogen bonds form chains extending parallel to the a-axis direction, which pack with partial inter­calation of the styryl and ester substituents., In the title mol­ecule, C21H20N2O3S, the styryl and ester substituents are displaced to opposite sides of the plane of the pyridine ring. In the crystal, C—H⋯O hydrogen bonds form chains extending parallel to the a-axis direction, which pack with partial inter­calation of the styryl and ester substituents. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (43.6%), C⋯H/H⋯C (15.6%), O⋯H/H⋯O (14.9%) and N⋯H/H⋯N (11.2%) contacts.

We present the first examples of tethered silanoxyiodination reactions of allylic alcohols. The products are usefulsilanediol organoiodide synthons and are formed with high regioselectivity and diastereocontrol. The reaction is scalable greater than 10-fold without loss of yield or selectivity. Furthermore, the products are starting materials for further transformations, including de-iodination, C–N bond installation, epoxide synthesis, and de-silylation. DFT calculations provide a basis for understanding the exquisite 6-endo selectivity of this silanoxyiodination reaction and show that the observed products are both kinetically and thermodynamically preferred.

The conformation of the title compound is partially determined by a strong, intra­molecular O—H⋯O hydrogen bond. In the crystal, C—H⋯O hydrogen bonds link the mol­ecules, forming chains along the a-axis direction, which are linked into strongly corrugated sheets parallel to the ac plane by C—H⋯O hydrogen bonds and C—H⋯π(ring) inter­actions. The sheets are associated through additional C—H⋯π(ring) inter­actions., The conformation of the title compound, C13H11NO2, is partially determined by a strong, intra­molecular O—H⋯O hydrogen bond. The crystal packing consists of strongly corrugated layers parallel to the ac plane and associated through C—H⋯π(ring) inter­actions. A Hirshfeld surface analysis of the crystal structure indicates that the most significant contributions to the crystal packing are from H⋯H (44.1%), C⋯H/H⋯C (29.4%) and O⋯H/H⋯O (17.3%) contacts.

The relative conformations about the three chiral carbon atoms are established. The two fused five-membered rings and their N-bound aromatic substituents form a pincer-like motif. In the crystal, a combination of C—H⋯O and C—H⋯N hydrogen bonds and C—H⋯π(ring) inter­actions leads to the formation of layers parallel to the bc plane with the di­phenyl­pyrrole groups protruding from both sides of the layers., In the title compound, C33H26N4O4, the two fused five-membered rings and their N-bound aromatic substituents form a pincer-like motif. The relative conformations about the three chiral carbon atoms are established. In the crystal, a combination of C—H⋯O and C—H⋯N hydrogen bonds and C—H⋯π(ring) inter­actions leads to the formation of layers parallel to the bc plane. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (44.3%), C⋯H/H⋯C (29.8%) and O⋯H/H⋯O (15.0%) contacts.

The title mol­ecule adopts an L-shaped conformation with a straight alkyl group. In the crystal, N—H⋯O hydrogen bonds form inversion dimers, which are connected into chains extending along the b-axis direction., The title mol­ecule, C17H26N2O, adopts an L-shaped conformation, with the straight n-decyl chain positioned nearly perpendicular to the di­hydro­benzimidazole moiety. The di­hydro­benzimidazole portion is not quite planar as there is a dihedral angle of 1.20 (6)° between the constituent planes. In the crystal, N—H⋯O hydrogen bonds form inversion dimers, which are connected into the three-dimensional structure by C—H⋯O hydrogen bonds and C—H⋯π(ring) inter­actions. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (75.9%), H⋯C/C⋯H (12.5%) and H⋯O/O⋯H (7.0%) inter­actions. Based on computational chemistry using the CE–B3LYP/6–31 G(d,p) energy model, C—H⋯O hydrogen bond energies are −74.9 (for N—H⋯O) and −42.7 (for C—H⋯O) kJ mol−1.

In the crystal of the title mol­ecular salt, ion pairs are linked by C—H⋯Br and N—H⋯Br hydrogen bonds, which are connected into helical chains extending along the c-axis direction by weak, electrostatic S⋯Br− inter­actions., In the title mol­ecular salt, C26H24N3S+·Br−, the dihedral angles between the thia­zole ring and its attached phenyl and benzoyl rings are 54.81 (7) and 85.51 (7)°, respectively. In the crystal, ion pairs are linked by C—H⋯Br and N—H⋯Br hydrogen bonds and are connected into helical chains extending along the c-axis direction by weak, electrostatic S⋯Br− inter­actions. A Hirshfeld surface analysis was performed, which showed the dominant role of H⋯H contacts (51.3%).

The mol­ecular and crystal structures of (I), C20H19N3O2, and (II), C22H21N3O, are similar because they differ only in the substituent at the hydrazide N atom where a phenyl­methyl­ene moiety for (II) is present instead of a furan­methyl­ene moiety for (I)., The conformation about the central benzene ring in the mol­ecule of (I), C20H19N3O2, is partially determined by an intra­molecular N—H⋯O hydrogen bond. In the crystal, chains parallel to the c axis are generated by inter­molecular N—H⋯O hydrogen bonds with the chains assembled into a three-dimensional network structure by inter­molecular C—H⋯O hydrogen bonds and C—H⋯π(ring) inter­actions. The mol­ecule of (II), C22H21N3O, differs from (I) only in the substituent at the hydrazide N atom where a phenyl­methyl­ene moiety for (II) is present instead of a furan­methyl­ene moiety for (I). Hence, mol­ecules of (I) and (II) show similarities in their mol­ecular and crystal structures. The conformation of the central portion of the mol­ecule of (II) is also therefore partially determined by an intra­molecular N—H⋯O hydrogen bond and inter­molecular N—H⋯O hydrogen bonds form chains parallel to the c axis. Likewise, the chains are connected into a three-dimensional network by C—H⋯O hydrogen bonds and C—H⋯π(ring) inter­actions.

The product obtained from the reaction of pyridine-2,3-dicarboxylic acid and hydrated copper(II) chloride in hot aqueous NaOH solution was determined by low temperature X-ray diffraction to be [Cu3(C6H4NO3)4(OH)2(H2O)2] n or [Cu3(μ-OH)2(μ-nicNO)4(H2O)2] n (nicNO is pyridine-3-carboxylate N-oxide), a structure obtained from room temperature data and reported previously. The present determination is improved in quality and treatment of the H atoms. A Hirshfeld surface analysis of the intermolecular interactions is presented.

In the crystal, the molecule of the title compound, C26H20N2O3, has crystallographically imposed twofold rotation symmetry. The crystal packing consists of layers parallel to the ab plane formed by O—H...N and C—H...O hydrogen bonds. Between the layers, C—H...π interactions are observed.

The heterocyclic portion of the tetra­hydro­iso­quinoline unit is planar and an intra­molecular N—H⋯N hydrogen bond and a C—H⋯π(ring) inter­action help to determine the overall conformation. In the crystal, O—H⋯O hydrogen bonds form inversion dimers, which are connected by C—H⋯O hydrogen bonds, forming layers parallel to (10)., In the title mol­ecule, C28H27N3O3S, the heterocyclic portion of the tetra­hydro­iso­quinoline unit is planar and an intra­molecular N—H⋯N hydrogen bond and a C—H⋯π(ring) inter­action help to determine the overall conformation. In the crystal, a layer structure with the layers parallel to (10) is generated by O—H⋯O and C—H⋯O hydrogen bonds.

Herein, a convenient and efficient synthesis of 7-benzoyl-6-(aryl)-6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-one derivatives was achieved from the reaction of isoquinolinium N-ylides, aromatic aldehydes, and heterocyclic 1,3-dicarbonyl compounds via one-pot three-component diastereoselective domino reaction in good-to-excellent yields. The advantages of this protocol are easily available starting materials, operational simplicity, and avoidance of hazardous organic solvents and catalyst. The synthesized products were characterized by IR, 1H NMR, 13C NMR and mass spectra. Additionally, the conclusive structure of target compounds was confirmed by X-Ray diffraction analysis.

As an extension of our interest in polyoxometalates (POMs) and lanthanoids, we report the design and synthesis of two polyoxometalate-based frameworks under hydrothermal conditions; [Ho4(PDA)4(H2O)11][(SiO4)@W12O36]·8H2O (1) and [Tb4(PDA)4(H2O)12][(SiO4)@W12O36]·4H2O (2) (H2PDA = 1,10-phenanthroline-2,9-dicarboxylic acid). Both hybrids have been characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and powder/single-crystal X-ray diffraction. According to the structural analysis, 1 and 2 consist of 2D-cationic coordination polymers based on the respective lanthanoids and PDA2- as well as Keggin anions that reside in the interspaces between two adjacent layers as discrete counterions connected by extensive hydrogen bonding. Although the overall structures of 1 and 2 are composed of cationic and anionic layers, there are many differences in the cationic layers such as various coordination modes of PDA2-, different void shapes, and the existence of dinuclear Tb(III) units only in 2. Frameworks 1 and 2 were further characterized by dc and ac magnetic measurements and both exhibit slow relaxation of magnetization at low temperatures under an applied dc field. Their single-molecule magnet (SMM) properties are investigated, where weak field-induced SMM behaviour is observed at low temperatures in dynamic magnetic studies.

The reaction of [(Ph2C2S2)2M] (M = Ni2+, Pd2+, Pt2+) with 2 equiv of RN≡C (R = Me (a), Bn (b), Cy (c), tBu (d), 1-Ad (e), Ph (f)) yields [(Ph2C2S2)M(C≡NR)2] (M = Ni2+, 4a–f; M = Pd2+, 5a–f; M = Pt2+, 6a–f), which are air-stable and amenable to chromatographic purification. All members have been characterized crystallographically. Structurally, progressively greater planarity tends to be manifested as M varies from Ni to Pt, and a modest decrease in the C≡N bond length of coordinated C≡NR appears in moving from Ni toward Pt. Vibrational spectroscopy (CH2Cl2 solution) reveals νC≡N frequencies for [(Ph2C2S2)M(C≡NR)2] that are substantially higher than those for free C≡NR and increase as M ranges from Ni to Pt. This trend is interpreted as arising from an increasingly positive charge at M that stabilizes the linear, charge-separated resonance form of the ligand over the bent form with lowered C–N bond order. UV–vis spectra reveal lowest energy transitions that are assigned as HOMO (dithiolene π) → LUMO (M–L σ*) excitations. One-electron oxidations of [(Ph2C2S2)M(C≡NR)2] are observed at ∼+0.5 V due to Ph2C2S22– → Ph2C2S–S• + e–. Chemical oxidation of [(Ph2C2S2)Pt(C≡NtBu)2] with [(Br-p-C6H4)3N][SbCl6] yields [(Ph2C2S–S•)Pt(C≡NtBu)2]+, identified spectroscopically, but in the crystalline state [[(Ph2C2S–S•)Pt(C≡NtBu)2]2]2+ prevails, which forms via axial Pt···S interactions and pyramidalization at the metal. Complete substitution of MeNC from [(Ph2C2S2)Ni(C≡NMe)2] by 2,6-Me2py under forcing conditions yields [(2,6-Me2py)Ni(μ2-η1,η1-S′,η1-S″-S2C2Ph2)]2 (8), which features a folded Ni2S2 core. In most cases, isocyanide substitution from [(Ph2C2S2)M(C≡NMe)2] with monodentate ligands (L = phosphine, CN–, carbene) leads to [(Ph2C2S2)M(L)(C≡NMe)]n (n = 0, 1−), wherein νC≡N varies according to the relative σ-donating power of L (9–21). The use of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) provides [(Ph2C2S2)M(IPr)(C≡NMe)] for M = Ni (18), Pd (19), but for Pt, attack by IPr at the isocyanide carbon occurs to yield the unusual η1,κC-ketenimine complex [(Ph2C2S2)Pt(C(NMe)(IPr))(C≡NMe)] (20).

In the title molecule, C20H24Br2N4, the imidazopyridine moiety is not planar as indicated by the dihedral angle of 2.0 (2)° between the constituent rings; the 4-dimethylaminophenyl ring is inclined to the mean plane of the imidazole ring by 27.4 (1)°. In the crystal, two sets of C—H...π(ring) interactions form stacks of molecules extending parallel to the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (42.2%), H...C/C...H (23.1%) and H...Br/Br...H (22.3%) interactions. The optimized structure calculated using density functional theory (DFT) at the B3LYP/ 6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated HOMO–LUMO energy gap is 2.3591 eV.

The title compound, C22H25NOS, consists of methylbenzylidene and benzothiazine units linked to a hexyl moiety, where the thiazine ring adopts a screw-boat conformation. In the crystal, inversion dimers are formed by weak C—HMthn...OBnzthz hydrogen bonds and are linked into chains extending along the a-axis direction by weak C—HBnz...OBnzthz (Bnz = benzene, Bnzthz = benzothiazine and Mthn = methine) hydrogen bonds. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (59.2%) and H...C/C...H (27.9%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. Computational chemistry indicates that in the crystal, the C—HBnz...OBnzthz and C—HMthn...OBnzthz hydrogen-bond energies are 75.3 and 56.5 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO—LUMO behaviour was elucidated to determine the energy gap. Moreover, the antibacterial activity of the title compound was evaluated against gram-positive and gram-negative bacteria.

In the title molecule, C20H21N3O3, the allyl substituent is rotated out of the plane of its attached phenyl ring [torsion angle 100.66 (15)°]. In the crystal, C—HMthphn...OMthphn (Mthphn = methoxyphenyl) hydrogen bonds lead to the formation of (100) layers that are connected into a three-dimensional network by C—H...π(ring) interactions, together with π–π stacking interactions [centroid-to-centroid distance = 3.7318 (10) Å] between parallel phenyl rings. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (48.7%) and H...C/C...H (23.3%) interactions. Computational chemistry reveals that the C—HMthphn...OMthphn hydrogen bond energy is 47.1 kJ mol−1. The theoretical structure, optimized by density functional theory (DFT) at the B3LYP/ 6–311 G(d,p) level, is compared with the experimentally determined molecular structure. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

The di­hydro­quinoline unit is slightly twisted and the hexyl groups extend out on either side. In the crystal, C—H⋯O hydrogen bonds form chains of mol­ecules extending along the b-axis direction, which are paired up by slipped π-stacking inter­actions. The ends of the hexyl groups from neighbouring chains are in contact but do not inter­calate., The asymmetric unit of the title compound, C22H31NO3, comprises of one mol­ecule. The mol­ecule is not planar, with the carboxyl­ate ester group inclined by 33.47 (4)° to the heterocyclic ring. Individual mol­ecules are linked by aromaticC—H⋯Ocarbon­yl hydrogen bonds into chains running parallel to [001]. Slipped π–π stacking inter­actions between quinoline moieties link these chains into layers extending parallel to (100). Hirshfeld surface analysis, two-dimensional fingerprint plots and mol­ecular electrostatic potential surfaces were used to qu­antify the inter­molecular inter­actions present in the crystal, indicating that the most important contributions for the crystal packing are from H⋯H (72%), O⋯H/H⋯O (14.5%) and C⋯H/H⋯C (5.6%) inter­actions.

In the title mol­ecule, the imidazolo­pyridine and phenyl rings are nearly co-planar, and the 12-bromo­dodecyl side chain is directed so as to give the complete mol­ecule a V-shape., The title compound, C24H30Br2N4O2, consists of a 2-(4-nitro­phen­yl)-4H-imidazo[4,5-b]pyridine entity with a 12-bromo­dodecyl substituent attached to the pyridine N atom. The middle eight-carbon portion of the side chain is planar to within 0.09 (1) Å and makes a dihedral angle of 21.9 (8)° with the mean plane of the imidazolo­pyridine moiety, giving the mol­ecule a V-shape. In the crystal, the imidazolo­pyridine units are associated through slipped π–π stacking inter­actions together with weak C—HPyr⋯ONtr and C—HBrmdc­yl⋯ONtr (Pyr = pyridine, Ntr = nitro and Brmdcyl = bromo­dodec­yl) hydrogen bonds. The 12-bromo­dodecyl chains overlap with each other between the stacks. The terminal –CH2Br group of the side chain shows disorder over two resolved sites in a 0.902 (3):0.098 (3) ratio. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (48.1%), H⋯Br/Br⋯H (15.0%) and H⋯O/O⋯H (12.8%) inter­actions. The optimized mol­ecular structure, using density functional theory at the B3LYP/ 6–311 G(d,p) level, is compared with the experimentally determined structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

The redetermined structure of the title compound, [H4N][C6H11Mo2O11]· H2O, was obtained from an attempt to prepare a glutamic acid complex from the [Co2Mo10H4O38]6− anion., The redetermined structure [for the previous study, see: Godfrey & Waters (1975 ▸). Cryst. Struct. Commun. 4, 5–8] of ammonium μ-oxido-μ-[1,5,6-tri­hydroxy­hexane-2,3,4-tris­(olato)]bis­[dioxidomolybdenum(V)] monohydrate, NH4[Mo2(C6H11O6)O5]·H2O, was obtained from an attempt to prepare a glutamic acid complex from the [Co2Mo10H4O38]6− anion. Subsequent study indicated the complex arose from a substantial impurity of mannitol in the glutamic acid sample used. All hydrogen atoms have been located in the present study and the packing displays N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds. A Hirshfeld surface analysis was also performed.

The title mol­ecule is only a few degrees out of planarity except for the 2-hy­droxy­ethyl substituent. In the crystal, O—H⋯N hydrogen bonds form stepped chains along the c-axis direction, which are formed into layers parallel to the bc plane by weak C—H⋯O and C—H⋯π (ring) inter­actions. Completion of the overall layer structure occurs through weak C—H⋯O, C—H⋯π (ring) and head-to-tail slipped π-stacking inter­actions., In the title mol­ecule, C12H13N3O2S, the benzo­thia­zine moiety is slightly non-planar, with the imidazolidine portion twisted only a few degrees out of the mean plane of the former. In the crystal, a layer structure parallel to the bc plane is formed by a combination of O—HHydethy⋯NThz hydrogen bonds and weak C—HImdz⋯OImdz and C—HBnz⋯OImdz (Hydethy = hy­droxy­ethyl, Thz = thia­zole, Imdz = imidazolidine and Bnz = benzene) inter­actions, together with C—HImdz⋯π(ring) and head-to-tail slipped π-stacking [centroid-to-centroid distances = 3.6507 (7) and 3.6866 (7) Å] inter­actions between thia­zole rings. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (47.0%), H⋯O/O⋯H (16.9%), H⋯C/C⋯H (8.0%) and H⋯S/S⋯H (7.6%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—H⋯N and C—H⋯O hydrogen-bond energies are 68.5 (for O—HHydethy⋯NThz), 60.1 (for C—HBnz⋯OImdz) and 41.8 kJ mol−1 (for C—HImdz⋯OImdz). Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state.

The title compound contains 1,4-benzo­thia­zine and 2,4-di­chloro­phenyl­methyl­idene units in which the di­hydro­thia­zine ring adopts a screw-boat conformation. In the crystal, inter­molecular C—HBnz⋯OThz (Bnz = benzene and Thz = thia­zine) hydrogen bonds form chains of mol­ecules extending along the a-axis direction which are connected to their inversion-related counterparts by C—HBnz⋯ClDchlphy (Dchlphy = 2,4-di­chloro­phen­yl) hydrogen bonds and C—HDchlphy⋯π (ring) inter­actions. These double chains are further linked by C—HDchlphy⋯OThz hydrogen bonds to form stepped layers approximately parallel to (012)., The title compound, C24H27Cl2NOS, contains 1,4-benzo­thia­zine and 2,4-di­chloro­phenyl­methyl­idene units in which the di­hydro­thia­zine ring adopts a screw-boat conformation. In the crystal, inter­molecular C—HBnz⋯OThz (Bnz = benzene and Thz = thia­zine) hydrogen bonds form chains of mol­ecules extending along the a-axis direction, which are connected to their inversion-related counterparts by C—HBnz⋯ClDchlphy (Dchlphy = 2,4-di­chloro­phen­yl) hydrogen bonds and C—HDchlphy⋯π (ring) inter­actions. These double chains are further linked by C—HDchlphy⋯OThz hydrogen bonds, forming stepped layers approximately parallel to (012). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (44.7%), C⋯H/H⋯C (23.7%), Cl⋯H/H⋯Cl (18.9%), O⋯H/H⋯O (5.0%) and S⋯H/H⋯S (4.8%) inter­actions. Hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—HDchlphy⋯OThz, C—HBnz⋯OThz and C—HBnz⋯ClDchlphy hydrogen-bond energies are 134.3, 71.2 and 34.4 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap. The two carbon atoms at the end of the nonyl chain are disordered in a 0.562 (4)/0.438 (4) ratio.

Two different mol­ecules with point group symmetry 2 are present in the crystal structure of the title compound. Each independent mol­ecule forms chains parallel to the b axis with its symmetry-related counterparts through C—H⋯π(ring) inter­actions., The asymmetric unit of the title compound, C23H28O4, comprises two half-mol­ecules, with the other half of each mol­ecule being completed by the application of twofold rotation symmetry. The two completed mol­ecules both have a V-shaped appearance but differ in their conformations. In the crystal, each independent mol­ecule forms chains extending parallel to the b axis with its symmetry-related counterparts through C—H⋯π(ring) inter­actions. Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (65.4%), H⋯C/C⋯H (21.8%) and H⋯O/O⋯H (12.3%) inter­actions. Optimized structures using density functional theory (DFT) at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structures in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

The title compounds, C8H14O4 and C16H26O7, are precursors to dendrimers. The strong and weak hydrogen bonds in their extended structures are described., In 2,2,5-trimethyl-1,3-dioxane-5-carb­oxy­lic acid, C8H14O4, the carboxyl group occupies an equatorial position on the 1,3-dioxane ring. In the crystal, O—H⋯O hydrogen bonds form chains of mol­ecules, which are linked into a three-dimensional network by C—H⋯O hydrogen bonds. The asymmetric unit of 2,2,5-trimethyl-1,3-dioxane-5-carb­oxy­lic anhydride, C16H26O7, consists of two independent mol­ecules, which are linked by C—H⋯O hydrogen bonds. In the crystal, these units are connected into corrugated layers two mol­ecules thick and parallel to the ab plane by additional C—H⋯O hydrogen bonds.

In the title molecule, C24H21N5O·H2O, the dihydrobenzodiazole moiety is not quite planar, while the whole molecule adopts a U-shaped conformation in which there is a close approach of the two benzyl groups. In the crystal, chains of alternating molecules and lattice water extending along [201] are formed by O—HUncoordW...ODhyr and O—HUncoordW...NTrz (UncoordW = uncoordinated water, Dhyr = dihydro and Trz = triazole) hydrogen bonds. The chains are connected into layers parallel to (010) by C—HTrz...OUncoordW hydrogen bonds with the dihydrobenzodiazole units in adjacent layers intercalating to form head-to-tail π-stacking [centroid-to-centroid distance = 3.5694 (11) Å] interactions between them, which generates the overall three-dimensional structure. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H...H (52.1%), H...C/C...H (23.8%) and O...H/H...O (11.2%) interactions. Hydrogen-bonding and van der Waals interactions are the dominant interactions in the crystal packing. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

Irradiation at 460 nm of [Mo3(μ3-S)(μ2-S2)3(S2CNR2)3]I ([2a]I, R = Me; [2b]I, R = Et; [2c]I, R = iBu; [2d]I, R = CH2C6H5) in a mixed aqueous-polar organic medium with [Ru(bipy)3]2+ as photosensitizer and Et3N as electron donor leads to H2 evolution. Maximum activity (300 turnovers, 3 h) is found with R = iBu in 1:9 H2O:MeCN; diminished activity is attributed to deterioration of [Ru(bipy)3]2+. Monitoring of the photolysis mixture by mass spectrometry suggests transformation of [Mo3(μ3-S)(μ2-S2)3(S2CNR2)3]+ to [Mo3(μ3-S)(μ2-S)3(S2CNR2)3]+ via extrusion of sulfur on a time scale of minutes without accumulation of the intermediate [Mo3S6(S2CNR2)3]+ or [Mo3S5(S2CNR2)3]+ species. Deliberate preparation of [Mo3S4(S2CNEt2)3]+ ([3]+) and treatment with Et2NCS21- yields [Mo3S4(S2CNEt2)4] (4), where the fourth dithiocarbamate ligand bridges one edge of the Mo3 triangle. Photolysis of 4 leads to H2 evolution but at ∼25% the level observed for [Mo3S7(S2CNEt2)3]+. Early time monitoring of the photolyses shows that [Mo3S4(S2CNEt2)4] evolves H2 immediately and at constant rate, while [Mo3S7(S2CNEt2)3]+ shows a distinctive incubation prior to a more rapid H2 evolution rate. This observation implies the operation of catalysts of different identity in the two cases. Photolysis solutions of [Mo3S7(S2CNiBu2)3]+ left undisturbed over 24 h deposit the asymmetric Mo6 cluster [(iBu2NCS2)3(μ2-S2)2(μ3-S)Mo3](μ3-S)(μ3-η2,η1-S',η1-S″-S2)[Mo3(μ2-S)3(μ3-S)(S2CNiBu2)2(μ2-S2CNiBu2)] in crystalline form, suggesting that species with this hexametallic composition and core topology are the probable H2-evolving catalysts in photolyses beginning with [Mo3S7(S2CNR2)3]+. When used as solvent, N,N-dimethylformamide (DMF) suppresses H2-evolution but to a greater degree for [Mo3S4(S2CNEt2)4] than for [Mo3S7(S2CNEt2)3]+. Recrystallization of [Mo3S4(S2CNEt2)4] from DMF affords [Mo3S4(S2CNEt2)4(η1,κO-DMF)] (5), implying that inhibition by DMF arises from competition for a Mo coordination site that is requisite for H2 evolution. Computational assessment of [Mo3S4(S2CNMe2)3]+ following addition of 2H+ and 2e- suggests a Mo(H)-μ2(SH) intermediate as the lowest energy species for H2 elimination. An analogous pathway may be available to the Mo6 cluster via dissociation of one end of the μ2-S2CNR2 ligand, a known hemilabile ligand type, in the [Mo3S4]4+ fragment.

In the title molecule, C11H10N2O, the dihydrobenzimidazol-2-one moiety is essentially planar, with the prop-2-yn-1-yl substituent rotated well out of this plane. In the crystal, C—HMthy...π(ring) interactions and C—HProp...ODhyr (Mthy = methyl, Prop = prop-2-yn-1-yl and Dhyr = dihydro) hydrogen bonds form corrugated layers parallel to (10\overline{1}), which are associated through additional C—HBnz...ODhyr (Bnz = benzene) hydrogen bonds and head-to-tail, slipped, π-stacking [centroid-to-centroid distance = 3.7712 (7) Å] interactions between dihydrobenzimidazol-2-one moieties. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H...H (44.1%), H...C/C...H (33.5%) and O...H/H...O (13.4%) interactions. Hydrogen-bonding and van der Waals interactions are the dominant interactions in the crystal packing. Computational chemistry calculations indicate that in the crystal, C—H...O hydrogen-bond energies are 46.8 and 32.5 (for C—HProp...ODhyr) and 20.2 (for C—HBnz...ODhyr) kJ mol−1. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

C22H26N2O, monoclinic, C2/c (no. 15), a = 47.4887(9) Å, b = 5.0220(1) Å, c = 16.4551(3) Å, β = 108.993(1)°, V = 3710.70(12) Å3, Z = 8, R gt (F) = 0.0345, wR ref(F 2) = 0.0935, T = 150(2) K. CCDC Nr.: 2025941

The title molecule, C29H29N3O4S, adopts a conformation with the two phenyl substituents disposed on opposite sides of the mean plane of the isoquinoline unit. In the crystal, corrugated layers of molecules are formed by N-H center dot center dot center dot O, C-H center dot center dot center dot N and C-H center dot center dot center dot S hydrogen bonds together with C-H center dot center dot center dot pi(ring) interactions. These layers are connected by C-H center dot center dot center dot O contacts. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H center dot center dot center dot H (45.2%), C center dot center dot center dot H/H center dot center dot center dot C (20.2%), O center dot center dot center dot H/H center dot center dot center dot O (15.8%) and N center dot center dot center dot H/H center dot center dot center dot N (11.0%) interactions.

C23H28N2O2, orthorhombic, Pbca (no. 61), a = 10.713(2) Å, b = 15.689(3) Å, c = 24.485(5) Å, V = 4115.2(14) Å3, Z = 8, R gt(F) = 0.0581, wR ref(F 2) = 0.1734, T = 120(2) K.

C24H20N2O2, monoclinic, P21/c (no. 14), a = 11.1713(3) Å, b = 17.7718(5) Å, c = 10.9852(3) Å, β = 118.990(1)°, V = 1907.67(9) Å3, Z = 4, R gt(F) = 0.0538, wR ref(F 2) = 0.1582, T = 296(2) K.

In the title molecule, C13H16N4O3, the mean planes of the phenyl and triazole rings are nearly perpendicular to one another as a result of the intramolecular C—H...O and C—H...π(ring) interactions. In the crystal, layers parallel to (101) are generated by O—H...N, N—H...O and N—H...N hydrogen bonds. The layers are connected by inversion-related pairs of C—H...O hydrogen bonds. The experimental molecular structure is close to the gas-phase geometry-optimized structure calculated by DFT methods. Hirshfeld surface analysis indicates that the most important interaction involving hydrogen in the title compound is the H...H contact. The contribution of the H...O, H...N, and H...H contacts are 13.6, 16.1, and 54.6%, respectively.

The reaction of ethylenediamine with four equivalents of chlorodiphenylphosphine in the presence of a base produced tetraphosphine [(Ph2P)2NCH2CH2N(PPh2)2] (1) which on further treatment with H2O2 (30% aq.) gave tetrakis(phosphineoxide) [(Ph2P(O))2NCH2CH2N((O)PPh2)2] (2). Treatment of 1 with two equivalents of Mo0, W0, NiII and RuII precursors yielded [{Mo(CO)4}2(Ph2P)2NCH2CH2N(PPh2)2] (3), [{W(CO)4}2(Ph2P)2NCH2CH2N(PPh2)2] (4) [{NiCl2}2(Ph2P)2NCH2CH2N(PPh2)2] (5) and [{Ru(η5-C5H5)PPh3}2(Ph2P)2NCH2CH2N(PPh2)2][Cl]2 (6). The reactions of 1 with [Cu(NCCH3)4][BF4] and [AuCl(SMe2)] resulted in the formation of di- and tetranuclear complexes [{Cu(NCCH3)2}2(Ph2P)2NCH2CH2N(PPh2)2][BF4]2 (7) and [{Au2Cl2}2(Ph2P)2NCH2CH2N(PPh2)2] (8), respectively. All the compounds were characterized by various spectroscopic methods and compounds 1–6 and 8 were characterized by single crystal X-ray diffraction analysis.

The pyridazine ring deviates slightly from planarity. In the crystal, ribbons consisting of inversion-related chains of mol­ecules extending along the a-axis direction are formed by C—HMthy⋯OCarbx (Mthy = methyl and Carbx = carboxyl­ate) hydrogen bonds. The ribbons are connected into layers parallel to the bc plane by inversion-related C—HBnz⋯π(ring) inter­actions., The title com­pound, C22H16N4O2, contains two pyridine rings and one meth­oxy­carbonyl­phenyl group attached to a pyridazine ring which deviates very slightly from planarity. In the crystal, ribbons consisting of inversion-related chains of mol­ecules extending along the a-axis direction are formed by C—HMthy⋯OCarbx (Mthy = methyl and Carbx = carboxyl­ate) hydrogen bonds. The ribbons are connected into layers parallel to the bc plane by C—HBnz⋯π(ring) (Bnz = benzene) inter­actions. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (39.7%), H⋯C/C⋯H (27.5%), H⋯N/N⋯H (15.5%) and O⋯H/H⋯O (11.1%) inter­actions. Hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—HMthy⋯OCarbx hydrogen-bond energies are 62.0 and 34.3 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/6-311G(d,p) level are com­pared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

Benzo[1,2-c:3,4-c′:5,6-c"]tri­thio­phene (D 3h-BTT) is an easily prepared electron donor that readily forms charge–transfer complexes with organic acceptors. We report here two crystal structures of its charge–transfer complexes with 7,7,8,8-tetra­cyano­quinodi­methane (TCNQ) and buckminsterfullerene (C60). The D 3h-BTT·TCNQ complex crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D 3h-BTT·C60·toluene complex, the central ring of BTT is ‘squeezed’ by the C60 mol­ecules from both faces. However, the degree of charge transfer is low., Benzo[1,2-c:3,4-c′:5,6-c′′]tri­thio­phene (D 3h-BTT) is an easily prepared electron donor that readily forms charge–transfer complexes with organic acceptors. We report here two crystal structures of its charge–transfer complexes with 7,7,8,8-tetra­cyano­quinodi­methane (TCNQ) and buckminsterfullerene (C60). The D 3h-BTT·TCNQ complex, C12H6S3·C12H4N4, crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D 3h-BTT·C60·toluene complex, C12H6S3·C60·C7H8, the central ring of BTT is ‘squeezed’ by the C60 mol­ecules from both faces. However, the degree of charge transfer is low. The C60 unit is disordered over two sites in a 0.766 (3):0.234 (3) ratio and was refined as a two-component inversion twin.

The title compound consists of a 1,2-di­hydro­quinoline-4-carboxyl­ate unit with 2-chloro­ethyl and propynyl substituents, where the quinoline moiety is almost planar and the propynyl substituent is nearly perpendicular to its mean plane. In the crystal, the mol­ecules form zigzag stacks along the a-axis direction through slightly offset π-stacking inter­actions between inversion-related quinoline moieties, which are tied together by inter­molecular C—HPrpn­yl⋯OCarbx and C—HChlethy⋯OCarbx (Prpnyl = propynyl, Carbx = carboxyl­ate and Chlethy = chloro­eth­yl) hydrogen bonds., The title compound, C15H12ClNO3, consists of a 1,2-di­hydro­quinoline-4-carb­oxyl­ate unit with 2-chloro­ethyl and propynyl substituents, where the quinoline moiety is almost planar and the propynyl substituent is nearly perpendicular to its mean plane. In the crystal, the mol­ecules form zigzag stacks along the a-axis direction through slightly offset π-stacking inter­actions between inversion-related quinoline moieties which are tied together by inter­molecular C—HPrpn­yl⋯OCarbx and C—HChlethy⋯OCarbx (Prpnyl = propynyl, Carbx = carboxyl­ate and Chlethy = chloro­eth­yl) hydrogen bonds. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (29.9%), H⋯O/O⋯H (21.4%), H⋯C/C⋯ H (19.4%), H⋯Cl/Cl⋯H (16.3%) and C⋯C (8.6%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, the C—HPrpn­yl⋯OCarbx and C—HChlethy⋯OCarbx hydrogen bond energies are 67.1 and 61.7 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

The title compound consists of a 3,6-bis­(pyridin-2-yl)pyridazine unit linked to a 4-[(prop-2-en-1-yl­oxy)meth­yl] moiety. The pyridine-2-yl rings are rotated slightly out of the plane of the pyridazine ring. In the crystal, C—H⋯N hydrogen bonds and C—H⋯π inter­actions link the mol­ecules, forming deeply corrugated layers approximately parallel to the bc plane and stacked along the a-axis direction., The title compound, C18H16N4O, consists of a 3,6-bis­(pyridin-2-yl)pyridazine moiety linked to a 4-[(prop-2-en-1-yl­oxy)meth­yl] group. The pyridine-2-yl rings are oriented at a dihedral angle of 17.34 (4)° and are rotated slightly out of the plane of the pyridazine ring. In the crystal, C—HPyrd⋯NPyrdz (Pyrd = pyridine and Pyrdz = pyridazine) hydrogen bonds and C—HPrp­oxy⋯π (Prp­oxy = prop-2-en-1-yl­oxy) inter­actions link the mol­ecules, forming deeply corrugated layers approximately parallel to the bc plane and stacked along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (48.5%), H⋯C/C⋯H (26.0%) and H⋯N/N⋯H (17.1%) contacts, hydrogen bonding and van der Waals inter­actions being the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, the C—HPyrd⋯NPyrdz hydrogen-bond energy is 64.3 kJ mol−1. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

In the title compound, C18H26BrNO, the dihydroindolone unit is slightly twisted. The n-decyl chains are fully extended and intercalate to form hydrophobic regions. The polar head groups are associated through C–H···O hydrogen bonds and C–Br···π(ring) interactions. In this study, we efficiently synthesized 5-bromo-1-decylindolin-2-one without isolation of the intermediate hydrazone by the Wolff–Kishner reduction of 2-(5-bromo-1-decyl-2-oxo-2,3-dihydro-1H-indol-3-ylidene)propanedinitrile with hydrazine hydrate.

In the title molecule, C17H23NO2, the dihydroindole portion is planar (r.m.s. deviation = 0.0157 Å) and the nonyl substituent is in an `extended' conformation. In the crystal, the nonyl chains intercalate and the dihydroindoledione units are associated through C—H...O hydrogen bonds to form micellar blocks. Based on the Hirshfeld surface analysis, the most important intermolecular interaction is the H...H interaction.

A series of hydroquinolines derivatives (2a-2c) have been achieved by a cyclocondensation reaction. The synthesis of 2-oxo −1,2-dihydroquinoline-4-carboxylic acid derivatives (3a-3c) has been carried out using alkylation reactions under phase transfer catalysis (PTC) conditions. The prepared products were characterized through spectroscopic NMR 1H and 13C, IR and single crystal X-ray diffraction techniques. 2D and 3D Hirshfeld surfaces (for 3a and 3b) studies were realized to understand non-bonding intermolecular interactions in solid phase crystal packing of the compound. With the optimized structures, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and clouds were obtained and evaluated. Good agreement was found between the calculated results and experimental data. Furthermore, the molecular docking study is performed to investigate binding patterns of the synthesized molecules (3a and 3b) into 1M17 inhibitor using Auto-Dock Vina program. The antioxidant activity of compounds (3a-3c) has been evaluated using DPPH free radical scavenging, ferric reducing (FRAP) power and β-carotene kinetic blanching assays. Both DPPH and FRAP methods confirmed that 3b had the best antioxidant activity followed by 3c. On the other hand, β-carotene bleaching assay showed the high activity of the product 3a.

In the title compound, the di­hydro­benzo­thia­zine moiety is folded about the S1⋯N1 axis. In the crystal, inversion dimers, generated by C—HBnz⋯NPrpnit (Bnz = benzene, Prpnit = propane­nitrile) hydrogen bonds, are linked into stepped ribbons extending parallel to [110] by C—HPrpnit⋯OThz (Thz = thia­zine) hydrogen bonds. The ribbons are joined into pairs by inversion-related C=O⋯Cl inter­actions., The title compound, C18H12Cl2N2OS, consists of a di­hydro­benzo­thia­zine unit linked by a –CH group to a 2,4-di­chloro­phenyl substituent, and to a propane­nitrile unit is folded along the S⋯N axis and adopts a flattened-boat conformation. The propane­nitrile moiety is nearly perpendicular to the mean plane of the di­hydro­benzo­thia­zine unit. In the crystal, C—HBnz⋯NPrpnit and C—HPrpnit⋯OThz (Bnz = benzene, Prpnit = propane­nitrile and Thz = thia­zine) hydrogen bonds link the mol­ecules into inversion dimers, enclosing R 2 2(16) and R 2 2(12) ring motifs, which are linked into stepped ribbons extending along [110]. The ribbons are linked in pairs by complementary C=O⋯Cl inter­actions. π–π contacts between the benzene and phenyl rings, [centroid–centroid distance = 3.974 (1) Å] may further stabilize the structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (23.4%), H⋯Cl/Cl⋯H (19.5%), H⋯C/C⋯H (13.5%), H⋯N/N⋯H (13.3%), C⋯C (10.4%) and H⋯O/O⋯H (5.1%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry calculations indicate that the two independent C—HBnz⋯NPrpnit and C—HPrpnit⋯OThz hydrogen bonds in the crystal impart about the same energy (ca 43 kJ mol−1). Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

1,2-Bis(pentaphenylphenyl)benzene (2) was synthesized by the cycloaddition of 1,2-bis(phenylethynyl)benzene and tetracyclone. Its X-ray structure was determined, and the molecule adopts a C2-symmetric conformation in the crystal. Monomethoxy and dimethoxy derivatives of compound 2 were also prepared, and dynamic NMR studies of these compounds yielded a free energy of activation for racemization (ΔG‡rac) of 20.3 kcal/mol at 423 K. The results are compared with estimates of ΔG‡rac for 2 by various DFT methods.

In the crystal structure of the title compound, C—H⋯O and C—H⋯N hydrogen bonds as well as C—H⋯π(ring) inter­actions link individual mol­ecules into a three-dimensional network., In the title mol­ecule, C19H16N4O, the planar pyrazolo­pyrimidine moiety is inclined to the attached phenyl rings by 35.42 (4) and 54.51 (6)°. In the crystal, adjacent mol­ecules are linked into chains parallel to [110] and [10] by C—H⋯O and C—H⋯N hydrogen bonds. Additional C—H⋯π(ring) inter­actions lead to the formation of the final three-dimensional network structure. The Hirshfeld surface analysis of the title compound suggests that the most significant contributions to the crystal packing are from H⋯H (48.2%), C⋯H/H⋯C (23.9%) and N⋯H/H⋯N (17.4%) contacts.

The title compound, C20H16Cl2N2O3S, is built up from a dihydrobenzothiazine moiety linked by –CH– and –C2H4– units to 2,4-dichlorophenyl and 2-oxo-1,3-oxazolidine substituents, where the oxazole ring and the heterocyclic portion of the dihydrobenzothiazine unit adopt envelope and flattened-boat conformations, respectively. The 2-carbon link to the oxazole ring is nearly perpendicular to the mean plane of the dihydrobenzothiazine unit. In the crystal, the molecules form stacks extending along the normal to (104) with the aromatic rings from neighbouring stacks intercalating to form an overall layer structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (28.4%), H...Cl/Cl...H (19.3%), H...O/O...H (17.0%), H...C/C...H (14.5%) and C...C (8.2%) interactions. Weak hydrogen-bonding and van der Waals interactions are the dominant interactions in the crystal packing. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO—LUMO behaviour was elucidated to determine the energy gap.

Four new stable nickel(II) complexes (1–4) with isothiosemicarbazone- and thiosemicarbazone-based ligands, namely, salicylidine S-propyl-isothiosemicarbazone hydroiodide (H2L1.HI), 5-bromo-2-hydroxybenzaldehyde S-propyl-isothiosemicarbazone hydroiodide (H2L2.HI), salicylidine-thiosemicarbazone (H2L3), and 5-bromo-2-hydroxybenzaldehyde thiosemicarbazone (H2L4) accompanied with triphenylphosphine and 2-methylimidazole as ancillary ligands were prepared in good yields. The complexes were characterized using analytical and spectroscopic techniques. Single-crystal X-ray crystallography revealed that the nickel complexes had distorted square planar geometries. H2L1.HI and H2L2.HI acted as NNO, while H2L3 and H2L4 acted as SNO tridentate donor ligands. In vitro antifungal and antibacterial activities of the Ni(II) complexes revealed that 3 exhibited the highest antifungal property especially against Candida albicans with an inhibition zone of 40 mm and a minimum inhibitory concentration, MIC = 1.56 mg/ml). Complex 2 showed the highest antibacterial property especially against Staphylococcus aureus with an inhibition zone of 30 mm and MIC of 1.56 mg/ml. Results indicate that these complexes are potential antimicrobial drugs for the treatment of infectious diseases for further research.

A new inorganic–organic hybrid based on an aspartate functionalized polyoxomolybdate, [pentaaquacobalt(II)]-μ-aspartate-[γ-octamolybdate]-μ-aspartate-[pentaaquacobalt(II)] tetrahydrate, [Co2(C4H6NO4)2(γ-Mo8O26)(H2O)10]·4H2O (1), has been synthesized under hydrothermal conditions from the reaction of an Evans–Showell-type polyoxometalate, (NH4)6[Co2Mo10H4O38], and L-aspartic acid. The complex exhibits a supramolecular three-dimensional framework structure in the crystal lattice. Compound 1 was structurally characterized by elemental analyses, IR and UV–Vis (diffuse reflectance) spectroscopy and single-crystal X-ray diffraction. In this compound, aspartic acid acts as a bridge between the two Co atoms and the Mo centres, with the –CH2COOH side chain directly linked to the Mo centre in γ-[Mo8O26]4− and the α-carboxylate side chain bound to the Co centre. Commonly, the binding of transition-metal complexes to POMs involves coordination of the metal to a terminal O atom of the POM so that 1, with a bridging ligand between Mo and Co atoms, belongs to a separate class of hybrid materials. While the starting materials are both chiral and one might expect them to form a chiral hybrid, the decomposition of the chiral Evans–Showell-type POM and its conversion to the centrosymmetric γ-octamolybdate POM, plus the presence of two aspartate ligands centrosymmetrically placed on either side of the POM, leads to the formation of an achiral hybrid. We have studied energetically by means of density functional theory (DFT) calculations and using the Bader's `atoms-in-molecules' analysis the electrostatically enhanced hydrogen bonds (EEHBs) observed in the solid state of 1, which are crucial for the formation of one-dimensional supramolecular assemblies.

The title compound, C18H12FNOS, is built up from a 4-fluorobenzylidene moiety and a dihydrobenzothiazine unit with a propynyl substituent, with the heterocyclic portion of the dihydrobenzothiazine unit adopting a shallow boat conformation with the propynyl substituent nearly perpendicular to it. The two benzene rings are oriented at a dihedral angle of 43.02 (6)°. In the crystal, C—HFlurphen...FFlurphen (Flurphen = fluorophenyl) hydrogen bonds link the molecules into inversion dimers, enclosing R 2 2(8) ring motifs, with the dimers forming oblique stacks along the a-axis direction. Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H...H (33.9%), H...C/C...H (26.7%), H...F/F...H (10.9%) and C...C (10.6%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

In the present study, two pyrazole-acetamide derivatives namely N‑(2‑aminophenyl)‑2‑(5‑methyl‑1H‑pyrazol‑3‑yl) acetamide (L1) and (E)‑N‑(2‑(1‑(2‑hydroxy‑6‑methyl‑4‑oxo‑4H‑pyran‑3‑yl)ethylideneamino)phenyl)‑2‑(5‑methyl‑1H‑pyrazol‑3‑yl) acetamide (L2) have been synthesized and characterized by infrared spectrophotometry (IR), nuclear magnetic resonance spectroscopy (NMR) and electrospray ionization-mass spectrometry (ESI-MS). Two coordination complexes of L1 and L2, namely [Co(L1)2(EtOH)2]·Cl2 (1) and [Cu(L2)]·H2O (2), respectively have been synthesized and characterized by elemental analysis and spectroscopic studies. The solid state structure of these two complexes was established by single crystal X-ray crystallography. In complex 1, the amide O and pyrazole N atoms of two molecules of L1 take part in coordination with octahedral Co(II) ions, the remaining two coordination sites being occupied by two EtOH molecules leading to a N2O4 coordination environment. On the other hand, the imine N atoms, pyrazole N and O atoms of the 2‑hydroxy‑6‑methyl‑4H‑pyran‑4‑one function present in L2 are involved in coordination with Cu(II) ions, resulting in a distorted square planar geometry displaying a N2O4 chromophore, in complex 2. The crystal packing analysis of 1 and 2, revealed 1D and 2D supramolecular architectures respectively, via various hydrogen bonding interactions, which are discussed in the present account. Furthermore, the antioxidant activity of the ligands and their complexes were determined in vitro by 1,1‑diphenyl‑2‑picrylhydrazyl (DPPH), 2,2′‑azino‑bis(3‑ethylbenzothiazoline‑6‑sulphonic acid (ABTS) and ferric reducing antioxidant power (FRAP), showing that the ligands L1 and L2 and complexes 1 and 2 present significant antioxidant activity.

The asymmetric unit of the title compound contains two independent organic mol­ecules which differ primarily in the dihedral angle between the aromatic rings, viz. 7.79 (7) and 29.89 (7)°. In the crystal, the components are linked by Owater—H⋯N, N—H⋯Owater and N—H⋯N hydrogen bonds, forming chains along the [100] direction. The chains are linked by C—H⋯O and C—H⋯N hydrogen bonds, forming layers parallel to the ab plane. Finally, the layers are linked by C—H⋯π inter­actions, forming a three-dimensional structure., The asymmetric unit of the title compound, C20H20N4O·0.5H2O, contains two independent organic mol­ecules (1 and 2) and a water mol­ecule of crystallization. The two mol­ecules differ primarily in the dihedral angles between the aromatic rings, which are 7.79 (7) and 29.89 (7)° in mol­ecules 1 and 2, respectively. In each mol­ecule there is intra­molecular C—H⋯O hydrogen bond forming an S(6) ring motif. In mol­ecule 1 there is an intra­molecular N—H⋯π(pyrazole) inter­action and an intra­molecular C—H⋯π(pyrazole) inter­action present. Mol­ecule 1 is linked to mol­ecule 2 by a C—H⋯π(benzene ring) inter­action. An intra­molecular N—H⋯N hydrogen bond and an intra­molecular C—H⋯N hydrogen bond are also present in mol­ecule 2. In the crystal, the three components are linked by Owater—H⋯N, N—H⋯Owater and N—H⋯N hydrogen bonds, forming chains along the [100] direction. The chains are linked by C—H⋯O and C—H⋯N hydrogen bonds, forming layers parallel to the ab plane. Finally, the layers are linked by C—H⋯π inter­actions, forming a three-dimensional structure.

Two new (4–5) and a known (3) derivatives of 1,2,4-triazolo [1,5-a]pyrimidine are synthesized and characterized through spectroscopic NMR, FT-IR and single crystal X-ray diffraction techniques. Along with experimental data, the predicted spectral data are obtained using density functional theory (DFT) at the B3LYP/6-31 + G (d,p) level of theory. The closest contacts between active atoms of the compounds are identified through Hirshfeld surface analysis and electrostatic potential map (EPM) studies. Relatively, good correlations were found between the experimental and predicted spectroscopic data with correlation coefficients higher than 90%. Hirshfeld surface analysis and EPM reveal that the closest interaction between the units of the compounds are between hydrogen atoms (39.6–46.3%). The antioxidant activity of 3–5 is evaluated using DPPH free radical scavenging and ferric reducing antioxidant power assays.

In the title compound, the pendant di­hydro­pyran ring is rotationally disordered in a 90.899 (3):0.101 (3) ratio with the orientation of each component largely determined by intra­molecular N—H⋯O hydrogen bonds. In the crystal, inversion-related mol­ecules form dimers through inter­molecular N—H⋯O hydrogen bonds with the dimers associated along the b-axis direction by slipped π-stacking inter­actions between the pyridyl and di­hydro­pyran rings., The title compound, C20H17N3O3 [systematic name: 2-(6-methyl-2,4-dioxo­pyran-3-yl­idene)-4-(pyridin-4-yl)-2,3,4,5-tetra­hydro-1H-1,5-benzodiazepine], is built up from a benzodiazepine ring system linked to pyridyl and pendant di­hydro­pyran rings, where the benzene and pyridyl rings are oriented at a dihedral angle of 43.36 (6)°. The pendant di­hydro­pyran ring is rotationally disordered in a 90.899 (3):0.101 (3) ratio with the orientation of each component largely determined by intra­molecular N—HDiazp⋯ODhydp (Diazp = diazepine and Dhydp = di­hydro­pyran) hydrogen bonds. In the crystal, mol­ecules are linked via pairs of weak inter­molecular N—HDiazp⋯ODhydp hydrogen bonds, forming inversion-related dimers with R 2 2(26) ring motifs. The dimers are further connected along the b-axis direction by π–π stacking inter­actions between the pendant di­hydro­pyran and pyridyl rings with centroid–centroid distances of 3.833 (3) Å and a dihedral angle of 14.51 (2)°. Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (50.1%), H⋯C/C⋯H (17.7%), H⋯O/O⋯H (16.8%), C⋯C (7.7%) and H⋯N/N⋯H (5.3%) inter­actions. Hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing.