title: Lipidic Carbo-benzenes: Molecular Probes of Magnetic Anisotropy and Stacking Properties of α-Graphyne.
abstract: Solubilization of the C18fundamental circuit of α-graphyne has been envisaged by decoration with aliphatic chains R = n-CnH2n+1. The synthesis and characterization of p-dialkyl-tetraphenyl-carbo-benzenes (n = 2, 8, 14, 20) are thus presented and compared to the monoalkyl series produced concomitantly. In both series, a dramatic enhancement of solubility in organic solvents (CH2Cl2, CHCl3) is observed for n ≥ 8, and in the dialkyl series, the melting-decomposition temperature of the solid products is shown to decrease linearly from 208 °C for n = 2 to 149 °C for n = 20. Fluoroalkyl analogues with R = n-C8H4F13are also described. The products display classical UV-vis electronic spectra of carbo-benzenes in solution (λmax= 445.5 ± 1 nm, ε ≈ 200 000 L·mol-1·cm-1). They are also characterized by UV-vis absorption in the solid state, which is found to be correlated with the color and crystal packing. The methylene groups of R provide an experimental probe of the magnetic anisotropy and aromaticity of the C18ring through the progressive NMR shielding of the1H nuclei from ca. 4.70 to 1.25 ppm going away from the border of the ring (as far as 8 Å away). All alkyl-carbo-benzenes were also found to be highly crystalline. Seven of them have been characterized by X-ray diffraction analysis and the C18columnar packing compared in a systematic manner. Crystals of the diethyl and bistetradecyl derivatives, containing no solvent molecule, provided the first examples of direct π-stacking of carbo-benzene rings, with inter-ring distances very close to calculated interlayer distances in AB and ABC α-graphityne (3.255 and 3.206 Å vs 3.266 and 3.201 Å, respectively).
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination) , 205 route de Narbonne, BP 44099, 31077 Toulouse Cedex 4, France.|Université de Toulouse , UPS, ICT-FR 2599, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Chongwei
authors.initials: C
authors.lastname: Zhu
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination) , 205 route de Narbonne, BP 44099, 31077 Toulouse Cedex 4, France.|Université de Toulouse , UPS, ICT-FR 2599, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Rives
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination) , 205 route de Narbonne, BP 44099, 31077 Toulouse Cedex 4, France.|Université de Toulouse , UPS, ICT-FR 2599, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Duhayon
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination) , 205 route de Narbonne, BP 44099, 31077 Toulouse Cedex 4, France.|Université de Toulouse , UPS, ICT-FR 2599, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Maraval
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination) , 205 route de Narbonne, BP 44099, 31077 Toulouse Cedex 4, France.|Université de Toulouse , UPS, ICT-FR 2599, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Remi
authors.identifier: 0000-0002-4491-6390
authors.initials: R
authors.lastname: Chauvin