Showing papers by "Sean Parkin published in 2004"
TL;DR: A series of crystalline acenedithiophenes with up to seven linearly fused rings and silylethynyl substituents are reported, designed to both improve solubility and enhance cofacial interactions in the solid.
222 citations
TL;DR: The synthesis and characterization of a series of alkoxy-substituted silylethynylated pentacene derivatives, which are easily prepared, soluble in common organic solvents, and stable both as solids and in solution.
112 citations
TL;DR: Proximally bridged calixarene compounds were synthesized via reaction between dialkyl- or diaryldichlorosilane and the corresponding calix[4]arene as mentioned in this paper.
43 citations
TL;DR: A modified procedure for the synthesis of polychlorinated biphenyls (PCBs) utilizing the Suzuki-coupling, a palladium-catalyzed cross-Coupling reaction, is described, which offers the advantage of high selectivity and moderate to good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.
30 citations
TL;DR: In this article, the first examples of five coordinate aluminum acetylide compounds chelated by a single ligand are reported, which are extremely moisture sensitive and readily hydrolyze to form aluminum hydroxides and with condensation form compounds of formula [L(tBu)Al]2O.
19 citations
TL;DR: In this article, the authors mined the Cambridge Structural Database for non-substituted, neutral imidazole derivatives and selected a chemically intuitive set of parameters to characterize the relationships between IMD rings in the solid states and discussed the complexities that can arise in the crude extraction of hydrogen bond strength from solid state data.
Abstract: The Cambridge Structural Database was mined for non N-substituted, neutral imidazole derivatives. Solid states with metal centres bound to the imidazole nitrogen atoms and ionic species were not included. The N–N, hydrogen-bound, tape motif was found to be a structural trend in the solid-state of neutral imidazole derivatives in the presence of possible competing hydrogen bonds and in highly steric environments. A chemically intuitive set of parameters was chosen to characterize the relationships between imidazole rings in the solid states. The choice of structural parameters and the values these parameters take as a function of substitution patterns of imidazole derivatives was discussed. The complexities that can arise in the crude extraction of hydrogen bond strength from solid state data was discussed.
17 citations
TL;DR: In this article, the structural modulations that lead to the large value of Z′ can be understood as resulting from the conflict between the necessity of filling space densely and uniformly and the tendency of unlike groups to be segregated spatially.
Abstract: Dimers of the partially fluorinated amphiphile 1-(perfluorobutyl)undecanoic acid, CF3(CF2)3(CH2)10COOH, crystallize in the same basic packing arrangement found for many n-alkyl carboxylic acids. The unit cell of the fluorinated compound, however, contains five independent molecules rather than the one found for most n-alkyl carboxylic acids including CH3(CH2)13COOH. The structures of the two C15 acids are compared. The structural modulations that lead to the large value of Z′ can be understood as resulting from the conflict between the necessity of filling space densely and uniformly and the tendency of unlike groups to be segregated spatially. The few other known structures of compounds with both (CF2)n and (CH2)m regions show evidence of the same conflict.
13 citations
TL;DR: In both molecules, the double bond connecting the aza-bicyclic and indole moieties has a Z geometry, and the3S configuration was obtained as an enantiomerically pure crystal and has the 3S configuration.
Abstract: The title compounds, C22H20N2O3S, (I), and C22H22N2O3S, (II), crystallize in space groups P-1 and P2(1)2(1)2(1), respectively. The indole rings are planar and the benzene ring of the phenylsulfonyl group makes a dihedral angle with the mean plane of the indole ring of 90.2 (2) degrees in (I) and 94.0 (2) degrees in (II). In both molecules, the double bond connecting the aza-bicyclic and indole moieties has a Z geometry. Compound (II) was obtained as an enantiomerically pure crystal and has the 3S configuration.
7 citations
TL;DR: Comparisons with structures known for other simple 2- and 2,2'-substituted biphenyl derivatives suggest that the molecular stacks found for 2-biphenylol are probable for related molecules.
Abstract: The substantially disordered structure of 2-biphenylol [Perrin et al. (1987). Acta Cryst. C43, 980-982; Kapon & Reisner (1988). Acta Cryst. C44, 2039] has been reinvestigated as a function of temperature. The structure was determined at 305, 294, 145 and 90 K; crystals were taken to the lowest temperature both rapidly and slowly (0.1 K min(-1)). The results of the previous room-temperature study were confirmed and no important structural change was found down to 90 K. Comparisons with structures known for other simple 2- and 2,2'-substituted biphenyl derivatives suggest that the molecular stacks found for 2-biphenylol are probable for related molecules. The disorder in 2-biphenylol allows the formation of some O-H...O bonds, but packing efficiency is a more important factor in this structure than is hydrogen bonding.
7 citations
TL;DR: A simple convergent synthesis of 3,5diazabicyclo[2.2]octane-2,6-diones (bicyclic N,N'-diacylaminals) has been developed, providing access to a large series of compounds differing only in their substituents at the bridgehead positions as discussed by the authors.
Abstract: A simple, convergent synthesis of 3,5-diazabicyclo[2.2.2]octane-2,6-diones (bicyclic N,N‘-diacylaminals) has been developed, providing access to a large series of compounds differing only in their substituents at the bridgehead positions. These compounds crystallize in several different forms, but always in such a way that each molecule forms four hydrogen bonds. The sheer number of bicyclic amidals that can be synthesized and crystallized provides an opportunity to elucidate crystal-engineering structure−structure relationship (SSR) principles.
6 citations
TL;DR: In this paper, the cycloaromatization of easily-prepared arenediynes is shown to be an efficient route to fused aromatic systems, but the requirement of very high temperatures to induce this reaction limits both scal- ability and generality.
Abstract: The cycloaromatization of easily-prepared arenediynes is an efficient route to fused aromatic systems, but the requirement of very high temperatures to induce this reaction limits both scal- ability and generality. We demonstrate that cycloaromatization can be induced by addition of a radical species to an arenediyne unit. Tethering this radical to the enediyne leads to the formation of larg- er fused systems, such as fluoranthenes and acephenanthrylenes, in a single step.
TL;DR: The dihedral angle between the benzene rings in the title compound, C12H7Cl3, is 4725 ǫ(4)° as discussed by the authors, which is the smallest angle known.
Abstract: The dihedral angle between the benzene rings in the title compound, C12H7Cl3, is 4725 (4)°
TL;DR: The title compound, C16H12N2S, has been synthesized by base-catalyzed condensation of 1-methylindole- 3-carboxaldehyde with thiophene-3-acetonitrile and has a thienyl-ring flip disorder.
Abstract: The title compound, C16H12N2S, has been synthesized by base-catalyzed condensation of 1-methylindole-3-carboxaldehyde with thiophene-3-acetonitrile. The product assumes an approximately planar Z configuration. The molecule has a thienyl-ring flip disorder.
TL;DR: In this article, a condensation reaction of 1-methyl-1H-indole-3-carboxaldehyde with 1-aza-bicyclo[2.2] octan-3one was described.
Abstract: Crystals of (Z)-2-(1-methyl-1H-indol-3-ylmethylene)-1-aza-bicyclo[2.2.2]octan-3-one (I) were obtained from a condensation reaction of 1-methyl-1H-indole-3-carboxaldehyde with 1-aza-bicyclo[2.2.2]octan-3-one and subsequent crystallization of the product from methanol. The isomeric (E)-2-(1-methyl-1H-indol-3-ylmethylene)-1-aza-bicyclo[2.2.2] octan-3-one hydrochloride (II) was obtained by treating a methanolic solution of I with a 1M solution of hydrogen chloride diethyl ether, followed by crystallization of resultant product from methanol. Crystal data: I, is monoclinic, P21, a = 5.7440(10), b = 11.102(2), c = 10.708(2) A, β = 91.751(10)°, and V = 682.5(2) A3 with Z = 2, for Dcal= 1.296 mg/m3 and II, is monoclinic, P21/c, a = 8.8510(2), b = 17.4990(5), c = 20.4300(5) A, β = 101.3620(12)°, V = 3102.26(14) with Z = 8, for Dcal= 1.316 mg/m3.
TL;DR: In this paper, the title compound, C15H16N2S, was obtained from the reaction of benzo[b]-thio-phene-3-aceto-nitrile with mechloreth-amine and subsequent crystallization of the product from hexane.
Abstract: Crystals of the title compound, C15H16N2S, were obtained from the reaction of benzo[b]thiophene-3-acetonitrile with mechlorethamine and subsequent crystallization of the product from hexane..
TL;DR: The title compound, C 16 H 12 Cl 2 N 2 , crystallizes in the centrosymmetric space group P2 1 /c and the pyrazole ring is planar.
Abstract: The title compound, C 16 H 12 Cl 2 N 2 , crystallizes in the centrosymmetric space group P2 1 /c. Two independent but chemically identical molecules comprise the asymmetric unit and in each of these the pyrazole ring is planar.
TL;DR: The title compound, C( 16)H(16)N(2)O, which contains a double bond connecting an azabicyclic ring system to an indol-3-ylmethylene group, crystallizes from a solution in ethyl acetate.
Abstract: The title compound, C16H16N2O, which contains a double bond connecting an azabicyclic ring system to an indol-3-ylmethylene group, crystallizes from a solution in ethyl acetate. The geometries of the two crystallographically independent molecules are nearly identical. The crystal packing of the title compound involves two types of intermolecular hydrogen bond.
TL;DR: In the crystal structures of both (I) and (II), the molecules are linked together by intermolecular O-H...N hydrogen bonds to form chains that run parallel to the a direction in (I), and parallel to b in (II).
Abstract: The crystal structures of the title compounds, 2 alpha,4 alpha-dibenzyl-3 alpha-tropanol (2 alpha,4 alpha-dibenzyl-8-methyl-8-azabicyclo[3.2.1]octan-3 alpha-ol), C(22)H(27)NO, (I), and 2 alpha,4 alpha-dibenzyl-3 beta-tropanol (2 alpha,4 alpha-dibenzyl-8-methyl-8-azabicyclo[3.2.1]octan-3 beta-ol), C(22)H(27)NO, (II), show that both compounds have a piperidine ring in a chair conformation and a pyrrolidine ring in an envelope conformation. Isomer (I) is asymmetric, the benzyl groups having different orientations, whereas isomer (II) is mirror symmetric, and the N and O atoms, the C atom attached to the hydroxy group, and the methyl C atom attached to the N atom lie on the mirror plane. In the crystal structures of both (I) and (II), the molecules are linked together by intermolecular O-H...N hydrogen bonds to form chains that run parallel to the a direction in (I) and parallel to b in (II).
TL;DR: The title compound, C15H10Cl2N2S, crystallizes in the centrosymmetric space group P21/c with one molecule in the asymmetric unit with an approximately planar configuration and has an E geometry about the azomethine C=N double bond.
Abstract: The title compound, C15H10Cl2N2S, crystallizes in the centrosymmetric space group P21/c with one molecule in the asymmetric unit. The molecule assumes an approximately planar configuration and has an E geometry about the azomethine C=N double bond. The crystal structure is stabilized by extensive hydrogen bonding.