Layered Compounds. XV. Synthesis and Properties of Multilayered Cyclophanes

Abstract

A series of multilayered cyclophanes up to sixfold were synthesized by 1,6-Hofmann elimination method. Odd layered and some dissymmetric ones were derived by means of cross-breeding pyrolysis of mixed quaternary ammonium hydroxides. The electronic spectra, absorption, emission, and CT absorption of charge-transfer complexes, of these cyclophanes exhibited remarkable transannular π-electronic interaction among chromophores closely stacked by methylene bridges. The interaction is increased eminently when the layer is varied from single to quadruple, but becomes less effective from quadruple to fivefold and no longer appreciable for more than fivefold one.

Homochiral [2.2]Paracyclophane Self‐Assembly Promoted by Transannular Hydrogen Bonding

“…[1] The rigid connectivity and positioning of its "bent and battered benzene rings" [2] are the basis for through-space (transannular p-p)a nd through-bond [s(bridge)-p(deck)] interactions [3] which strongly perturb the chemical, optical, and electronic properties of the molecule.The synthetic chemistry of pCp is quite mature and allows functional groups to be precisely positioned on the rings and bridges [2,4] -two common ring substitution patterns are shown in Figure 1b. [11] Theprospect of delocalized electronic states emerging for extended p-stacked cyclophanes dates back to the seminal work of the groups of Chow, [12] Misumi, [13] and Staab, [14] whose tediously prepared multitiered structures (e.g., Figure 1c) showed, for example,l onger wavelength absorption and emission maxima upon increasing the number of intervening benzene rings.T he single-molecule conductance of such constructs has only recently been measured. [11] Theprospect of delocalized electronic states emerging for extended p-stacked cyclophanes dates back to the seminal work of the groups of Chow, [12] Misumi, [13] and Staab, [14] whose tediously prepared multitiered structures (e.g., Figure 1c) showed, for example,l onger wavelength absorption and emission maxima upon increasing the number of intervening benzene rings.T he single-molecule conductance of such constructs has only recently been measured.…”

Naphthalene-based oligothiophene-stacked polymers

“…55 We have recently reported the synthesis of aromatic-ring-layered polymers using xanthene compounds as scaffolds. [40][41][42][43][44][45][46][47] [2.2] Paracyclophane-layered polymers, which mimic multilayered cyclophanes, [56][57][58][59] exhibited fluorescence resonance energy transfer from the layered paracyclophanes to the end-capping groups. The use of xanthene as a scaffold enabled us to introduce various aromatic compounds, such as phenylenes, 44 carbazoles, 45 thiophenes 46 and anthracene, 47 into the polymers, with the distance between the layered aromatic units being B4.5 Å .…”

Recent Theoretical and Experimental Advances in the Electronic Circular Dichroisms of Planar Chiral Cyclophanes

“…These features are more apparent for up to four-layered cyclophanes. This was explained primarily by the transannular p-p interaction/delocalization, while the effect of deformation of the benzene rings was thought to be rather negligible [53]. Despite the UV spectral study, only a limited amount of effort has been devoted so far to the study of the chiroptical properties of layered cyclophanes.…”

“…As unique C 2 -symmetric transition metal complexes, the atropisomeric ( (53) were prepared from (R p )-4-amino-and (R p )-4-carboxy-[2.2]paracyclophanes, respectively. The CD spectra of 52 and 53 were significantly different from each other (Fig.…”