566 research outputs found
7-Chloro-4-(2-hydroxyethylamino)quinolin-1-ium chloride
The use of the EPSRC X-ray crystallographic service at the University of Southampton, England [Coles, S. J. & Gale, P. A. (2012). Chem. Sci. 3, 683-689.]), and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil). Structural studies are supported by the Ministry of Higher Education (Malaysia) and the University of Malaya through the High-Impact Research scheme (UM·C/HIR/MOHE/SC/3).Peer reviewedPublisher PD
4-[(2-Chloroethyl)amino]quinolinium chloride monohydrate
In the title salt hydrate, C11H12ClN2
+·Cl−·H2O, the quinolinium core is essentially planar (r.m.s. deviation = 0.027 Å) with the chloroethyl side chain being almost orthogonal to the core [C—N—C—C torsion angle = −80.0 (3)°]. In the crystal packing, the water molecule bridges three species, forming donor interactions to two chloride anions and accepting a hydrogen bond from the quinolinium H atom. The chloride anion accepts a hydrogen bond from the amine N atom with the result that a two-dimensional supramolecular array is formed in the ac plane. A C—H⋯Cl interaction also occurs
2-[(E)-2-(3,4-Dichlorobenzylidene)hydrazin-1-yl]quinoxaline
The use of the EPSRC X-ray crystallographic service (Coles & Gale, 2012[Coles, S. J. & Gale, P. A. (2012). Chem. Sci, 3, 683-689.]) at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil). Structural studies are supported by the Ministry of Higher Education (Malaysia) and the University of Malaya through the High-Impact Research scheme (UM.C/HIR/MOHE/SC/3).Peer reviewedPublisher PD
7-Chloro-4-[(E)-(3-chlorobenzylidene)hydrazinyl]-1λ4-quinolinium 3-chlorobenzoate
The title salt, C16H12Cl2N3
+·C7H4ClO2
−, features a non-planar cation, the dihedral angle between the quinolinium and benzene residues being 18.98 (10)°. The cation adopts an E conformation about the C—N bond, and the amine group is oriented towards the quinolinium residue. In the crystal, N—H⋯O hydrogen bonds link two cations with two anions, forming a 20-membered {⋯OCO⋯HNC3NH}2 synthon. The dimeric units are connected into a linear supramolecular chain along [100] via π–π interactions [centroid–centroid distance = 3.5625 (13) Å]
Benzyl N-(1-{N′-[(E)-2,3-dihydroxybenzylidene]hydrazinecarbonyl}-2-hydroxyethyl)carbamate dihydrate
The organic molecule in the title dihydrate, C18H19N3O6·2H2O, adopts a twisted U-shape with the major twists evident about the chiral C atom [the C—N—C—C torsion angle is −88.2 (4) °] and about the oxygen–benzyl bond [C—O—C—C = 74.2 (4) °]. The conformation about the imine bond [1.290 (4) Å] is E and an intramolecular O—H⋯N hydrogen bond helps to establish the near coplanarity of the hydroxybenzene and hydrazine groups. The crystal packing features O—H⋯O and N—H⋯O hydrogen bonds, leading to two-dimensional supramolecular arrays in the ab plane with weak C—H⋯π connections between the arrays
N-(4-Bromophenyl)pyrazine-2-carboxamide
The molecule of the title compound, C11H8BrN3O, is close to planar (r.m.s. deviation of all 16 non-H atoms = 0.103 Å), a conformation stabilized by an intramolecular N—H⋯N hydrogen bond, which generates an S(5) ring. In the crystal structure, supramolecular chains mediated by C—H⋯O contacts (along a) are linked into a double layer via N⋯Br halogen bonds [3.207 (5) Å] and C—Br⋯π interactions [Br⋯ring centroid(pyrazine) = 3.446 (3) Å]. The layers stack along the b axis via weak π–π interactions [ring centroid(pyrazine)⋯ring centroid(benzene) distance = 3.803 (4) Å]
Adaptation and enslavement in endosymbiont-host associations
The evolutionary persistence of symbiotic associations is a puzzle.
Adaptation should eliminate cooperative traits if it is possible to enjoy the
advantages of cooperation without reciprocating - a facet of cooperation known
in game theory as the Prisoner's Dilemma. Despite this barrier, symbioses are
widespread, and may have been necessary for the evolution of complex life. The
discovery of strategies such as tit-for-tat has been presented as a general
solution to the problem of cooperation. However, this only holds for
within-species cooperation, where a single strategy will come to dominate the
population. In a symbiotic association each species may have a different
strategy, and the theoretical analysis of the single species problem is no
guide to the outcome. We present basic analysis of two-species cooperation and
show that a species with a fast adaptation rate is enslaved by a slowly
evolving one. Paradoxically, the rapidly evolving species becomes highly
cooperative, whereas the slowly evolving one gives little in return. This helps
understand the occurrence of endosymbioses where the host benefits, but the
symbionts appear to gain little from the association.Comment: v2: Correction made to equations 5 & 6 v3: Revised version accepted
in Phys. Rev. E; New figure adde
N′-[(1E)-(5-Nitrofuran-2-yl)methylidene]thiophene-2-carbohydrazide: crystal structure and Hirshfeld surface analysis
In the title carbohydrazide, C10H7N3O4S, the dihedral angle between the terminal five-membered rings is 27.4 (2)°, with these lying to the same side of the plane through the central CN2C(=O) atoms (r.m.s. deviation = 0.0403 Å), leading to a curved molecule. The conformation about the C=N imine bond [1.281 (5) Å] is E, and the carbonyl O and amide H atoms are anti. In the crystal, N-H...O hydrogen bonds lead to supramolecular chains, generated by a 41 screw-axis along the c direction. A three-dimensional architecture is consolidated by thienyl-C-H...O(nitro) and furanyl-C-H...O(nitro) interactions, as well as [pi]-[pi] interactions between the thienyl and furanyl rings [inter-centroid distance = 3.515 (2) Å]. These, and other, weak intermolecular interactions, e.g. nitro-N-O...[pi](thienyl), have been investigated by Hirshfeld surface analysis, which confirms the dominance of the conventional N-H...O hydrogen bonding to the overall molecular packing
N-(2-Chloroethyl)pyrazine-2-carboxamide
In the title molecule, C7H8ClN3O, the pyrazine and amide groups are almost co-planar [N—C—C—N torsion angle = −2.4 (2) °], a conformation stabilized by an intramolecular N—H⋯N hydrogen bond. The chloroethyl group lies out of the plane [N—C—C—Cl = −65.06 (17) °]. In the crystal, the presence of N—H⋯N hydrogen bonds leads to the formation of a C(6) supramolecular chain along the b axis. The carbonyl-O atom accepts two C—H⋯O interactions. These, plus Cl⋯Cl short contacts [3.3653 (6) Å], consolidate the packing of the chains in the crystal
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