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

Communications Biophysics

Contains reports on five research projects

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