Search tips
Search criteria

Results 1-25 (25)

Clipboard (0)

Select a Filter Below

Year of Publication
Document Types
1.  Synthesis and ESR studies of 2'-deoxyuridines tethered with alkynyl, rod-like linkages# 
Sonogashira coupling of diacetyl 5-ethynyl-2'-deoxyuridine with diacetyl 5-iodo-2'-deoxyuridine gave the acylated ethynediyl-linked 2'-deoxyuridine dimer (3b) (63%) that was deprotected with ammonia/methanol to ethynediyl-linked 2'-deoxyuridines (3a) (79%). Reaction of 5-ethynyl-2'-deoxyuridine (1a) with 5-iodo-2'-deoxyuridine gave the furopyrimidine linked to 2'-deoxyuridine (78%). Catalytic oxidative coupling of 1a (O2, CuI, Pd/C, DMF) gave the butadiynediyl-linked 2'-deoxyuridines (4) (84%). Double Sonogashira coupling of 5-iodo-2'-deoxyuridine with 1,4-bis(ethynyl)benzene gave 1,4-phenylenediethyne-bridged 5-ethynyl-2'-deoxyuridines (5, 83%). Cu-catalyzed cycloisomerization of dimers 4 and 5 gave their furopyrimidine derivatives. One electron addition to 1a, 3a and 4 gave the anion radical whose ESR spectra showed the unpaired electron largely localized at C6 of one uracil ring (17 G doublet) at 77 K. For the ethynediyl- and butadiynyl-linked uridines 3a and 4 the ESR spectra of their one electron oxidized species at 77 K showed that the unpaired electron is delocalized over both rings. Thus structures 3a and 4 provide an efficient electronic link for hole conduction between the uracil rings. However, for the excess electron, an activation barrier prevents coupling to both rings. These dimeric structures could provide a gate that could separate hole transfer from electron transport between strands in DNA systems. In the crystal structure of acylated dimer 3b the bases were found in the anti position to each other across the ethynyl link. Similar anti conformation was preserved in the derived furopyrimidine–deoxyuridine dinucleoside.
PMCID: PMC4596529  PMID: 19609983
Alkynes; Electron delocalization; ESR; Deoxyuridine; Furopyrimidine; Nucleosides; Synthesis
2.  Crystal structure of O-isopropyl [bis­(tri­methyl­sil­yl)amino](tert-butyl­amino)­phosphino­thio­ate 
[Bis(tri­methyl­sil­yl)amino](tert-butyl­imino)­thio­phospho­rane reacts in benzene with isopropyl alcohol via 1,2-addition of an iPrO–H bond across the P=N bond, resulting in the title compound, C13H35N2OPSSi2. In the mol­ecule, the P atom possesses a distorted tetra­hedral environment involving two N atoms from (Me3Si)2N– and tBuNH– groups, one O atom from an iPrO group and one S atom, therefore the mol­ecule has a stereocenter on the P atom but crystal symmetry leads to a racemate. In the crystal, a pair of enanti­omers form a centrosymmetric dimer via a pair of N—H⋯S hydrogen bonds.
PMCID: PMC4331855  PMID: 25705495
crystal structure; (tri­methyl­sil­yl)amino; phosphino­thio­ate; N—H⋯S hydrogen bonding
3.  2-Methyl­benzene-1,3-di­ammonium dinitrate 
In the crystal structure of the title salt, C7H12N2 2+·2NO3 −, the nitrate ions are located in the vicinity of the protonated amine groups, accepting strong N—H⋯O hydrogen bonds. Each ammonium group is involved in a total of three such inter­actions with neighbouring nitrate ions, generating a three-dimensional network. In addition, there are π–π inter­actions between the aromatic rings of centrosymmetrically related di­ammonium moieties, with a centroid–centroid distance of 3.682 (1) Å.
PMCID: PMC3998351  PMID: 24764912
4.  N-(4-Meth­oxy­phen­yl)-6-methyl-2-phenyl-5-{[4-(tri­fluoro­meth­yl)anilino]meth­yl}pyrimidin-4-amine 
The title compound, C26H23F3N4O, crystallizes with two symmetry-independent mol­ecules in the asymmetric unit, denoted A and B, which differ mainly in the rotation of the meth­oxy­phenyl ring. The –CF3 group of mol­ecule B is disordered by rotation, with the F atoms split over two sets of sites; the occupancy factor for the major component is 0.853 (4). The dihedral angles between the pyrimidine ring and the attached phenyl, meth­oxy­phenyl and tri­fluoro­methyl­phenyl rings are 8.1 (2), 37.5 (2) and 70.7 (2)°, respectively, in mol­ecule A, and 9.3 (2), 5.3 (2) and 79.7 (2)° in mol­ecule B. An intra­molecular N—H⋯N hydrogen bond occurs in each mol­ecule. In the crystal, two crystallographically independent mol­ecules associate into a dimer via a pair of N—H⋯N hydrogen bonds, with a resulting R 2 2(12) ring motif and π–π stacking inter­actions [centroid–centroid distance = 3.517 (4) Å] between the pyrimidine rings. For the A mol­ecules, there are inter­molecular C—H⋯O hydrogen bonds between an aryl C atom of meth­oxy­phenyl ring and a meth­oxy O atom of an adjacent mol­ecule. A similar inter­action is lacking in the B mol­ecules.
PMCID: PMC3885078  PMID: 24454254
5.  Poly[[μ-bis­(4-nitro­phen­yl) phosphato-κ2 O,O′]sodium] 
The title compound, [Na(C12H8N2O8P)], consists of one Na+ cation and one bis­(p-nitro­phen­yl)phosphate anion with a considerable distortion of the phosphate tetra­hedron due to the presence of two P—O ester bonds. The anion bridges five Na+ cations whereby each cation is chelated by the nitro O atoms of one anion and bonded via a nitro O atom and phosphate O atoms to four other anions. This bridging arrangement leads to the formation of double layers parallel to (001). Adjacent layers are linked through weak C—H⋯O hydrogen bonds.
PMCID: PMC3793696  PMID: 24109283
6.  5-Iodo-3-phenyl-2,1-benzoxazole 
The title compound, C13H8INO, was prepared by a condensation reaction of 4-nitro­benzene with phenyl­acetonitrile in NaOH–ethanol solution. There are two independent mol­ecules in the asymmetric unit, in which the dihedral angles between the benzene ring and the benzoisoxazole unit are 4.2 (3) and 4.1 (3)°. The crystal packing is governed by C—H⋯N, C—I⋯π and C—I⋯O inter­actions.
PMCID: PMC3629537  PMID: 23634055
7.  (4R*,4aR*,7aS*)-5-Oxo-6-phenyl-4a,5,6,7,7a,8-hexa­hydro-4H-furo[2,3-f]isoindole-4-carb­oxy­lic acid 
The asymmetric unit of the title compound, C17H15NO4, contains two independent mol­ecules with similar geometric parameters. In both mol­ecules, the conformation of the cyclo­hexene ring is half-chair, while the pyrrolidinone ring adopts an envelope conformation with the γ-carbon atom of the α-pyrrolidinone ring as the flap. In the crystal, O—H⋯O hydrogen bonds between the carb­oxylic and carbonyl groups link alternate independent mol­ecules into chains propagating in the b-axis direction. The crystal packing also features weak C—H⋯π inter­actions.
PMCID: PMC3569801  PMID: 23424547
8.  5-[(3,5-Dichloro­anilino)meth­yl]-N-(3,5-dichloro­phen­yl)-6-methyl-2-phenyl­pyrimidin-4-amine 
In the title compound, C24H18Cl4N4, the pyrimidine ring makes dihedral angles of 19.1 (2), 4.1 (2) and 67.5 (2)°, respectively, with phenyl and two benzene rings, and the mol­ecular conformation is stabilized by an intra­molecular N—H⋯N hydrogen bond closing a six-membered ring with an S(6) motif. In the crystal, a pair of inter­molecular N—H⋯N hydrogen bonds connect two mol­ecules, forming inversion dimers with R 2 2(12) motifs. C—H⋯π inter­actions links the dimers into a chain running along the a-axis direction. There are also π–π stacking inter­actions [centroid–centroid distance = 3.666 (4) Å] between the benzene rings of adjacent chains.
PMCID: PMC3588999  PMID: 23476235
9.  5-[(4-Fluoro­anilino)meth­yl]-6-methyl-N-(4-methyl­phen­yl)-2-phenyl­pyrimidin-4-amine 
In the title compound, C25H23FN4, the pyrimidine ring makes dihedral angles of 11.3 (2), 24.5 (2) and 70.1 (2)° with the phenyl and two benzene rings, and the mol­ecular conformation is stabilized by an intra­molecular N—H⋯N hydrogen bond with an S(6) ring motif. In the crystal, a pair of weak C—H⋯F hydrogen bonds link two mol­ecules into an inversion dimer with an R 2 2(16) motif. In the dimer, there is also an inter­molecular π–π stacking inter­action [centroid–centroid distance = 3.708 (4) Å] between the fluorinated benzene rings. The dimers are further linked by a C—H⋯π inter­action, so forming a column along the c axis.
PMCID: PMC3470299  PMID: 23125712
10.  2,2′-[(1E,2E)-1,2-Bis(hy­droxy­imino)­ethane-1,2-di­yl]dipyridinium hexa­chloridorhenate(IV) 
The title salt, (C12H12N4O2)[ReCl6], consists of 2,2′-[(1E,2E)-1,2-bis­(hy­droxy­imino)­ethane-1,2-di­yl]dipyridinium cations and [ReCl6]2− anions which are both located on inversion centres. Each cation consists of a glyoxime moiety attached to two protonated pyridine rings in ortho positions. In the crystal, E,E isomers of the cation are observed which differ in the spatial arrangement of the pyridine rings. These rings are positionally disordered over two positions with site-occupancy factors of 0.786 (7) and 0.214 (7). The geometry of the cation is compared with that of a recently reported dipyridyl­glyoxime with the same configuration. The cations and anions are involved in a network of inter­molecular O—H⋯Cl, N—H⋯Cl and C—H⋯Cl hydrogen bonds.
PMCID: PMC3435597  PMID: 22969470
11.  5-[(4-Eth­oxy­anilino)meth­yl]-N-(2-fluoro­phen­yl)-6-methyl-2-phenyl­pyrimidin-4-amine 
The asymmetric unit of the title compound, C26H25FN4O, consists of two symmetry-independent mol­ecules, denoted A and B. The conformation of each mol­ecule is mainly determined by an intra­molecular N—H⋯N hydrogen bond, which closes a six-membered ring. The dihedral angles between the pyrimidine ring and the phenyl, fluorophenyl and ethoxyphenyl rings are 15.4 (2), 28.4 (2) and 77.5 (2)°, respectively, in mol­ecule A, and 15.9 (2), 2.7 (2) and 61.8 (2)° in mol­ecule B. Inter­molecular N—H⋯N hydrogen bonds and π–π stacking inter­actions between pyrimidine rings [centroid–centroid distance = 3.692 (4) Å] connect mol­ecules A and B into dimers and C—H⋯O hydrogen bonds link the dimers into zigzag chains along [011]. The (4-eth­oxy­anilino)methyl group of the B mol­ecule is disordered over two sets of sites, the occupancy factor for the major component being 0.900 (2).
PMCID: PMC3379319  PMID: 22719517
12.  (E)-4-{2-[(2-Hy­droxy­naphthalen-1-yl)methyl­idene]hydrazinecarbon­yl}pyridinium nitrate 
The title compound, C17H14N3O2 +·NO3 −, is an aroylhydrazone-based material consisting of a 4-(hydrazinecarbon­yl)pyridinium cation and a nitrate anion. In the cation, the dihedral angle between the benzene ring and the naphthalene ring system is 2.20 (7)°. In the cation, the configuration about the C=N bond is E. There is an intra­molecular O—H⋯N hydrogen bond in the cation, and the supra­molecular structure is stabilized by inter­molecular N—H⋯O hydrogen bonds and weak C—H⋯O contacts between the cation and the nitrate anion.
PMCID: PMC3275047  PMID: 22346992
13.  N-(2-Fluoro­phen­yl)-5-[(4-meth­oxy­phen­yl)amino­meth­yl]-6-methyl-2-phenyl­pyrimidin-4-amine 
The conformation of the title mol­ecule, C25H23FN4O, is mainly determined by an intra­molecular N—H⋯N hydrogen bond closing a six-membered ring and the dihedral angles between the pyrimidine ring and the three benzene rings which are 12.8 (2), 12.0 (2) and 86.1 (2)°. An intra­molecular N—H⋯F inter­action also occurs. The crystal stucture is stabilized by weak C—H⋯O and C—H⋯π inter­actions. An inter­molecular N—H⋯N inter­action is also observed.
PMCID: PMC3238833  PMID: 22199686
14.  Two penta­dehydro­peptides with different configurations of the ΔPhe residues 
Comparison of the crystal structures of two penta­dehydro­peptides containing ΔPhe residues, namely (Z,Z)-N-(tert-butoxy­carbonyl)­glycyl-α,β-phenyl­alanyl­glycyl-α,β-phenyl­alanyl­glycine (or Boc0–Gly1–ΔZPhe2–Gly3–ΔZPhe4–Gly5–OH) methanol solvate, C29H33N5O8·CH4O, (I), and (E,E)-N-(tert-butoxy­carbonyl)­glycyl-α,β-phenyl­alanyl­glycyl-α,β-phenyl­alanyl­glycine (or Boc0–Gly1–ΔEPhe2–Gly3–ΔEPhe4–Gly5–OH), C29H33N5O8, (II), indicates that the ΔZPhe residue is a more effective inducer of folded structures than the ΔEPhe residue. The values of the torsion angles ϕ and ψ show the presence of two type-III′ β-turns at the ΔZPhe residues and one type-II β-turn at the ΔEPhe residue. All amino acids are linked trans to each other in both peptides. β-Turns present in the peptides are stabilized by intra­molecular 4→1 hydrogen bonds. Mol­ecules in both structures form two-dimensional hydrogen-bond networks parallel to the (100) plane.
PMCID: PMC2855584  PMID: 20203407
15.  3-Hy­droxy-1-methyl-2-[4-(piperidin-1-yl)phen­yl]quinolin-4(1H)-one 
There are two structurally similar but crystallographically independent mol­ecules (A and B) in the asymmetric unit of the title compound, C21H22N2O2, which are linked via two O—H⋯O hydrogen bonds. An intramolecular O—H⋯O hydrogen bond also occurs in each molecule. In the crystal, the A and B mol­ecules are further linked through C—H⋯O inter­actions. The benzene ring is twisted at an angle of 69.9 (1) and 83.4 (1)° relative to the 1,4-dihydro­quinoline skeleton in mol­ecules A and B, respectively. Adjacent 1,4-dihydro­quinoline units of mol­ecules A are parallel, while mol­ecules A and B are oriented at an angle of 32.8 (1)°.
PMCID: PMC3051995  PMID: 21522406
16.  2-(Furan-2-yl)-3-hy­droxy-4H-chromen-4-one 
In the crystal structure of the title compound, C13H8O4, the inversely oriented mol­ecules form inversion dimers through pairs of O—H⋯O hydrogen-bonding inter­actions. An intramolecular O—H⋯O hydrogen bond occurs. In the packing of the mol­ecules, the nearly planar 2-(furan-2-yl)-4H-chromene units [dihedral angle between the chromene and furan rings = 3.8 (1)°] are either parallel or inclined at an angle of 80.7 (1)°.
PMCID: PMC3051447  PMID: 21522958
17.  trans-Dioxidotetra­pyridine­rhenium(V) triiodide 
In the title salt, [ReO2(C5H5N)4]I3, the cation and anion are both located on centres of symmetry. The ReV atom adopts a trans-ReO2N4 octa­hedral coordination and short intra­molecular C—H⋯O contacts occur within the cation. In the crystal, the cations form layers perpendicular to [100] and a weak C—H⋯O inter­action links the cations.
PMCID: PMC2970012  PMID: 21577416
18.  Extensive hydrogen-bonding network and an unusual cation conformation in [tris­(hydroxy­meth­yl)methyl]­ammonium tetra­oxidorhenate(VII) 
The title compound, (C4H12NO3)[ReO4], contains two cations and two anions in the asymmetric unit, related by a non-crystallographic centre of symmetry. The crystal structure is stabilized by an extensive hydrogen-bonding network with the formation of puckered layers perpendicular to [001]. In the tris­(hydroxy­meth­yl)ammonium cations, intra­molecular O—H⋯O hydrogen bonds are present with the formation of an S 1 1(6) graph-set motif. The crystal structure is further consolid­ated by N—H⋯O hydrogen bonds.
PMCID: PMC2977137  PMID: 21583437
19.  Di-μ-oxido-bis­{[(R,R)-(+)-1-amino-2-(3-methoxy-2-oxidobenzyl­ideneamino-κ2 O 2,N)-1,2-diphenyl­ethane-κN]oxidovanadium(V)} dihydrate 
In the crystal structure of the title compound, [V2(C22H21N2O2)2O4]·2H2O, oxide-bridged dimers of the complex are linked to water mol­ecules by hydrogen-bonding inter­actions. The two five-membered chelate rings in the dimeric mol­ecule both adopt twist conformations. Each VV atom is six-coordinated by one oxide group and by two N and one O atom of the tridentate Schiff base ligand, and is bridged by two additional oxide atoms. The metal centre has a distorted octa­hedral coordination. The monoanionic ligands occupy one equatorial and two axial positions.
PMCID: PMC2961776  PMID: 21202755
20.  4,4′-Bipyridine–butane-1,2,3,4-tetra­carboxylic acid (1/1) 
The title compound, C10H8N2·C8H10O8, is an example of a system with a short O⋯H⋯N hydrogen bond [O⋯N = 2.565 (3) Å]. The crystal structure comprises a 1:1 adduct between 4,4′-bipyridine and butane-1,2,3,4-tetra­carboxylic acid, where both components are centrosymmetric. The component mol­ecules are linked through strong O⋯H⋯N hydrogen bonds, forming chains extending approximately along [11]. The chains are inter­connected by O⋯H⋯O hydrogen bonds and weak stacking inter­actions involving the pyridyl rings of the 4,4′-bipyridine mol­ecules [centroid–centroid distance = 3.73 (2) Å and inter­planar distance = 3.35 (1) Å]. The H atom of the short O⋯H⋯N hydrogen bond is disordered over two positions with site occupancy factors of ca 0.6 and 0.4. One methylene group is disordered over two positions; the site occupancy factors are ca 0.9 and 0.1.
PMCID: PMC2961488  PMID: 21202711
21.  (R)-(−)-3-Hydroxy­quinuclidinium chloride 
The quinuclidinium cation of the title compound, C7H14NO+·Cl−, shows a twist along the C—N pseudo-threefold axis, with N—C—C—C torsion angles of −16.0 (1), −16.9 (1) and −15.6 (1)°. The crystal structure is stabilized by N—H⋯Cl and O—H⋯Cl hydrogen bonds, forming infinite chains along the a and b axes.
PMCID: PMC2961231  PMID: 21202330
22.  The low-temperature phase of morpholinium tetra­fluoro­borate 
The crystal structure of the low-temperature form of the title compound, C4H10NO+·BF4 −, was determined at 80 K. Two reversible phase transitions, at 158/158 and 124/126 K (heating/cooling), were detected by differential scanning calorimetry for this compound, and the sequence of phase transitions was subsequently confirmed by single-crystal X-ray diffraction experiments. The asymmetric unit at 80 K consists of three BF4 − tetra­hedral anions and three morpholinium cations (Z′ = 3). Hydrogen-bonded morpholinium cations form chains along the [100] direction. The BF4 − anions are connected to these chains by N—H⋯F hydrogen bonds. In the crystal structure, two different layers perpendicular to the [001] direction can be distinguished, which differ in the geometry of the hydrogen bonds between cationic and anionic species.
PMCID: PMC2961037  PMID: 21202061
23.  catena-Poly[[bis­[2-(2,3-dimethyl­anilino)benzoato-κO]cadmium(II)]-di-μ-3-pyridylmethanol-κ2 N:O;κ2 O:N] 
In the crystal structure of the title compound, [Cd(C15H14NO2)2(C6H7NO)2]n, the Cd atom displays a distorted octa­hedral geometry, including two pyridine N atoms and two hydroxyl O from four symmetry-related 3-pyridylmethanol (3-pyme) ligands and two carboxylate O atoms from mefenamate [2-(2,3-dimethyl­anilino)benzoate] anions. The Cd atoms are connected via the bridging 3-pyme ligands into chains, that extend in the a-axis direction. The Cd atom is located on a center of inversion, whereas the 3-pyme ligands and the mefenamate anions occupy general positions.
PMCID: PMC2960823  PMID: 21201841
24.  10-Methyl-9-(2-nitro­phenoxy­carbon­yl)acridinium trifluoro­methane­sulfonate 
The crystal structure of the title compound, C21H15N2O4 +·CF3O3S−, is stabilized by C—H⋯O and C—H⋯F hydrogen bonds, by C—F⋯π, N—O⋯π and S—O⋯π inter­actions, and by O⋯O [2.70 (4) Å] and O⋯F [2.85 (1) or 2.92 (1) Å] contacts; π–π interactions are also present. In the packing of the mol­ecules, acridine units are either parallel or inclined at an angle of 12.5 (1)°. The nitrophenoxycarbonyl unit is disordered over two position; the site occupancy factors are 0.89 and 0.11.
PMCID: PMC2960374  PMID: 21201404
25.  Bis(guanidinium) trans-diaqua­bis(malonato-κ2 O,O′)cobaltate(II) 
In the title compound, (CH6N3)2[Co(C3H2O4)2(H2O)2], the anions lie on crystallographic centres of inversion. The crystal structure adopts a layered structure, stabilized by an extensive network of N—H⋯O and O—H⋯O hydrogen bonds. One H atom of the guanidinium cation does not participate in any strong hydrogen bonds.
PMCID: PMC2915119  PMID: 21200534

Results 1-25 (25)