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Molecular Ladder (molecular + ladder)
Selected AbstractsSupramolecular aggregation in 4,4,-bipyridin-1,1,-ium dichloride, 4,4,-bipyridin-1,1,-ium dinitrate and 4,4,-bipyridin-1-ium bromideACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2003Peter Abeta Iyere 4,4,-Bipyridin-1,1,-ium dichloride [C10H10Cl2N2 (I)] and 4,4,-bipyridin-1,1,-ium dinitrate [C10H10N4O6 (II)] have been prepared and the crystal structures determined at 90.0,(2),K. Molecules of (I) are linked by two chlorine-bridged, three-centered N,H,Cl hydrogen bonds into chains along the b axis. The chains are coupled by weak C,H,Cl interactions into a molecular ladder along the c direction. In (II) each nitrate is coordinated to four bipyridinium ions through the interplay of the N,H,O and C,H,O contacts, resulting in a three-dimensional zigzag sheet on the ab plane. The sheets stack along the c axis. In 4,4,-bipyridin-1-ium bromide monohydrate [C10H9N2+·Br,·H2O (III)] the bipyridinium ions are linked by three-center N,H,N, hydrogen bonds in a head-to-tail fashion to form chains along the b axis. The chains are linked by C,H,Br and C,H,OH2 into a three-dimensional framework. [source] Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diaminesACTA CRYSTALLOGRAPHICA SECTION B, Issue 3-2 2002Dorcas M. M. Farrell (S)-Malic acid forms a salt with N,N,-dimethylpiperazine, [MeN(CH2CH2)2NMe]H22+·2C4H5O5, (1) (triclinic, P1, Z, = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4,-bipyridyl, (S)-malic acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z, = 1) and (3) (monoclinic, C2, Z, = 1), while racemic malic acid with 4,4,-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P21/c, Z, = 1). In each of (2), (3) and (4) the components are linked by O,H,N and N,H,O into chains of alternating bipyridyl and malate units, which are linked into sheets by O,H,O hydrogen bonds. In each of the 1:1 adducts (5) and (6), formed by, respectively, (S)-malic acid and racemic malic acid with 1,2-bis(4,-pyridyl)ethene, the diamine is disordered over two sets of sites, related by a 180° rotation about the N,N vector. In (5), (C12H10N2)H+·C4H5O5, (triclinic, P1, Z, = 1), the components are again linked by a combination of N,H,O and O,H,O hydrogen bonds into sheets, while in (6) (triclinic, P, Z, = 0.5) there is only partial transfer of the H atom from O to N and the malate component is disordered across a centre of inversion. With 1,4-diazabicyclo[2.2.2]octane, racemic malic acid forms a 1:2 salt, [(C6H12N2)H2]2+·2C4H5O5, (7) (monoclinic, P21/c, Z, = 2), while (S)-malic acid forms a 1:1 adduct, (8) (monoclinic, P21, Z, = 3). There are thus six independent molecular components in each. In (7) the ions are linked by an extensive series of N,H,O and O,H,O hydrogen bonds into a three-dimensional framework, but in (8) there is extensive disorder involving all six components, and no refinement proved to be feasible. [source] A hydrogen-bonded dimer in 6-(4-bromophenyl)-3-methyl-1-phenyl-4,5-dihydro-1H -pyrazolo[3,4- b]pyridine and a chain of rings built from N,H...N and C,H...,(pyridine) hydrogen bonds in 3-(4-nitrophenyl)-4-phenyl-1H -pyrazolo[3,4- b]pyridineACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Jairo Quiroga In 6-(4-bromophenyl)-3-methyl-1-phenyl-4,5-dihydro-1H -pyrazolo[3,4- b]pyridine, C19H16BrN3, the reduced pyridine ring adopts a conformation that is close to a screw-boat form. Molecules are linked by pairs of symmetry-related C,H...,(arene) hydrogen bonds into cyclic centrosymmetric dimers. Molecules of 3-(4-nitrophenyl)-4-phenyl-1H -pyrazolo[3,4- b]pyridine, C18H12N4O2, are linked into centrosymmetric R22(8) dimers by pairs of symmetry-related N,H...N hydrogen bonds, and these dimers are linked by pairs of C,H...,(pyridine) hydrogen bonds to form a chain of edge-fused rings, or a molecular ladder, along [100]. The molecular aggregation in this compound is completed by two weak C,H...O hydrogen bonds, one of which links the chains along [100] into sheets. [source] Nine isomeric nitrobenzylidene-iodoanilines: interplay of C,H,O hydrogen bonds, iodo,nitro interactions and aromatic ,,, stacking interactionsACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2002Christopher Glidewell Nine isomeric nitrobenzylidene-iodoanilines, O2NC6H4CH= NC6H4I [(I),(IX)], have been synthesized and the structures of all except 4-nitrobenzylidene-4,-iodoaniline (IX) have been analyzed. 2-Nitrobenzylidene-2,-iodoaniline (I) contains isolated molecules, while 3-nitrobenzylidene-2,-iodoaniline (II) and 2-nitrobenzylidene-3,-iodoaniline (IV) both contain chains of molecules linked by C,H,O hydrogen bonds: similar chains in 4-nitrobenzylidene-2,-iodoaniline (III) are further linked by aromatic ,,, stacking interactions, forming sheets. In both 3-nitrobenzylidene-3,-iodoaniline and 4-nitrobenzylidene-3,-iodoaniline, (V) and (VI), a combination of C,H,O hydrogen bonds and iodo,nitro interactions generates molecular ladders that are linked into sheets by aromatic ,,, stacking interactions, while in 2-nitrobenzylidene-4,-iodoaniline and 3-nitrobenzylidene-4,-iodoaniline, (VII) and (VIII), which both crystallize with Z,,=,2 in C2/c and P, respectively, the combination of C,H,O hydrogen bonds and iodo,nitro interactions generates sheets, which in (VIII) are further linked by ,,, stacking interactions to form a three-dimensional structure. The 4,4,-isomer (IX) crystallizes in Fdd2 with Z,,=,2, but both molecules are intractably disordered. [source] Polymorphs and pseudopolymorphs of N,N,-dithiobisphthalimideACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2002Dorcas M. M. Farrell N,N,-Dithiobisphthalimide, C16H8N2O4S2 (I), forms a wide range of polymorphs and solvates (pseudopolymorphs). When (I) is crystallized from methanol it yields a solvent-free polymorph (4), in Pna21 with Z, = 1, in which the molecules are linked into chains by a single C,H,O hydrogen bond: crystallization from either acetonitrile or dimethylformamide produces a monoclinic polymorph (5), in P21/c with Z, = 2, also solvent-free, in which the molecules are linked into molecular ladders. Nitromethane forms a monosolvate, C16H8N2O4S2·CH3NO2 (6), in P21/c with Z, = 1, in which the solvent molecules are linked to the molecules of (I) not only via a conventional C,H,O hydrogen bond but also via a polarized multicentre interaction involving all three C,H bonds of the solvent molecule. Chlorobenzene forms a precise hemisolvate, C16H8N2O4S2·0.5C6H5Cl (7), in P with Z, = 1, while ethylbenzene forms an approximate hemisolvate 2C16H8N2O4S2·0.913C6H5C2H5·0.087H2O (8), in P21/c with eight molecules of (I) per unit cell. In both solvates the molecules of (I) are linked, in (7) by ,,, stacking interactions augmented by weak C,H,O hydrogen bonds and in (8) by stronger C,H,O hydrogen bonds: the solvent molecules lie in isolated cavities, disordered across inversion centres in (7) and fully ordered in general positions in (8). Crystallization of (I) either from tetrahydrofuran or from wet tert -butanol yields isomorphous solvates (9) and (10), respectively, in C2/c with Z, = 0.5, in which molecules of (I) lie across twofold rotation axes and are linked by ,,, stacking interactions and very weak C,H,O hydrogen bonds, forming a framework enclosing continuous channels: highly disordered solvent molecules lie within these channels. p -Xylene and toluene form isomorphous hemisolvates (11) and (12) with unit cells metrically very similar to those of (9) and (10), but in P21/n with Z, = 1: in these two solvates the molecules of (I) are linked into a framework by very short C,H,O hydrogen bonds; the solvent molecules lie within continuous channels, but they are localized across inversion centres so that the toluene is disordered across an inversion centre. [source] Amino-substituted O6 -benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structuresACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2002Antonio Quesada The structures of eight 2,4,6-trisubstituted-5-nitrosopyrimidines (one of which crystallizes in two polymorphs) have been determined, including seven O6 -benzyl derivatives which are potential, or proven, in vitro inhibitors of the human DNA-repair protein O6 -alkylguanine-DNA-transferase. In the derivatives having an amino substituent at the 4-position, an intramolecular N,H,O hydrogen bond with the nitroso O as an acceptor leads to an overall molecular shape similar to that of substituted purines. There is a marked propensity for these nitroso compounds to crystallize with Z, = 2. The structure of an analogue with no nitroso group is also reported for comparative purposes. Compounds containing the N -alkyl substituents ,NHCH2COOEt, ,NHCH2CH2COOEt and ,NHCH(CH2Ph)COOEt, derived from amino acid esters, exhibit a rich variety of conformational behaviour, and in all of the nitroso compounds the bond lengths provide strong evidence for a highly polarized electronic structure. Associated with this polarization is extensive charge-assisted hydrogen bonding between the molecules, leading to supramolecular aggregation in the form of finite (zero-dimensional) aggregates, chains, molecular ladders, sheets and frameworks. [source] | ||||||||||