Noncovalent Interactions between Stacked Arenes in 1,8‐Bis‐(1‐naphthyl)‐naphthalenes

Abstract

A number of 1,8‐bis(1‐naphthyl)‐naphthalenes, bearing different substituents in the 1‐naphthyl moieties have been prepared to investigate the noncovalent interactions between the stacked arenes. The best geometries were determined by means of DFT calculations, and experimentally checked by NMR and electronic circular dichroism (ECD). High temperature NMR spectroscopy allowed for the determination of the balance between dispersive and electrostatic contributions (ratio between two diastereomeric syn/anti isomers of compounds 1–6), while ECD analysis of the syn isomers of compounds 3–5 allowed for a deeper insight on the electrostatic contributions that drive the geometry between the interacting rings. The two rings preferentially adopt a parallel displaced geometry, whose interaction energy is strongly influenced by the electrostatic features of the two naphthyl rings, and that dispersive forces play a very minor role.

1,8‐Diarylnaphthalenes: Synthesis, Properties, and Applications

“…Interconversion of atropisomers occurs through a T-shaped transition state. [39][40][41]148] The unsubstituted peri-phenyl rings of 1,8-diphenylnaphthalene rotate freely around the C aryl À C naphth bond. The introduction of an ortho or meta substituent on both peri-phenyl rings results in the formation of two chiral anti-isomers and one meso synisomer (for principles of chirality and dynamic stereochemistry see monography [149] ).…”

“…ring are on the same or opposite sides of the central naphthalene framework (this case is discussed in detail in the article [148] ). However, as in the paradigmatic case of biphenyl and binaphthyl, the two peri-aryl rings are not exactly perpendicular to the plane of the central naphthalene moiety, and this geometrical situation implies that two diastereomeric anti-conformations may exist.…”

“…[130] In cases of substitution in peri-naphthyl rings, this value can reach 31.8 kcal/mol at 113 °C. [148] Scheme 61. Synthesis of bismerocyanines 201 and 202 using salt 190.…”

“…In the case of 1,8‐di(naphthyl‐1)naphthalene 13 and its symmetrically substituted derivatives (Figure 2, A ), in principle, only two conformations should exist: syn‐ and anti‐ conformations, where atoms C(5), C(6), C(7), and C(8) of the α‐naphthyl ring are on the same or opposite sides of the central naphthalene framework (this case is discussed in detail in the article [148] ). However, as in the paradigmatic case of biphenyl and binaphthyl, the two peri ‐aryl rings are not exactly perpendicular to the plane of the central naphthalene moiety, and this geometrical situation implies that two diastereomeric anti ‐conformations may exist.…”

“…R=H, R 1 =Me, R 2 =H F, H, F H, H, OMe 27.7 (71 °C)[a] 31.3 (113 °C)[a] 28.6 (87 °C)[a] 3.2 : 1 3.5 : 1 2.7 :1 [148] R 1 =Me, R 2 =HOMe, H H, OMe 29.8 (92 °C)[a] 29.7 (111 °C)[a] 29.5 (96 °C)[a] 1.5 : 1 2.1 : 1 1.2 : 1[148] 24.8 (> 60 °C)[a] ~1 : 1[37] 11 (-55 °C)[a] 3.3 : 1 (À 65 °C)[113] …”