Geländerhelicale Moleküle

Abstract

Eine neue Generation chiraler, funktionalisierter Molekülgerüste bahnt sich mit den von p‐Terphenyl abgeleiteten Titelverbindungen an. Die orthogonal zu den Helicenen wie ein Treppengeländer schraubenförmig in die Länge gezogenen Moleküle (siehe schematische Darstellung) sind einfach zugänglich und leicht funktionalisierbar. Sie sind durch spontane Enantiomerentrennung, sehr hohe Drehwerte und intensiven Circulardichroismus gekennzeichnet.

Synthesis of an Orthogonal Topological Analogue of Helicene

“…and showed the formation of supramolecular nanotubes based on naphthalenediimide derivatives 10. This arrangement of the aromatic systems is also illustrated covalently by Vögtle’s “Geländer” molecule11 (Scheme c), but without the formation of a full turn.…”

“…The high specific rotation of 1 ( α =+1590°) is in accordance with what could be expected for a helical molecule31 (e.g. ( M )‐[5]helicene ([ α ]${{{\hfill \atop 578\hfill}}}$ =−1670°),32 ( M )‐[6]helicene (Scheme a, [ α ]${{{\hfill \atop 578\hfill}}}$ =−3570°),7a or the Geländer molecule (Scheme c, [ α ]${{{\hfill \atop 578\hfill}}}$ =+2608°)]11. However, care must be exercised when comparing specific rotations at different wavelengths.…”

“…The structure and absolute configuration of the pentamer were elucidated from a combination of NMR spectroscopic data, optical properties, Xray structures, and by comparison of an experimental electronic circular dichroism spectrum to a calculated spectrum. Keywords: bicyclic compounds · circular dichroism · helical structures · pyridopyridines · quinolines systems is also illustrated covalently by Vçgtles "Geländer" molecule [11] (Scheme 1 c), but without the formation of a full turn.…”

Time‐dependent density functional theory calculations on the chiroptical properties of rubroflavin: Determination of its absolute configuration by comparison of measured and calculated CD spectra

“…While CNDO/2S performs fairly well as far as the sign and wavelength of the first Cotton effect of the decomposition product is concerned 1 such semiempirical calculations on the CD spectrum of parent rubroflavin did not even qualitatively reproduce the main features of the observed spectrum. Because in the last years time‐dependent density functional theory (TDDFT) has become an important tool for theoretical studies on the chiroptical properties of midsized molecules 3–7 we examined the CD spectrum of parent rubroflavin using this theory. To obtain a calculated CD spectrum of the title compound, we optimized the structures of 30 plausible isomers (quinoid, phenolic, and others)* of rubroflavin with density functional theory (DFT).…”

Atropisomerization of di-para-substituted propyl-bridged biphenyl cyclophanes

“…In most cases known in the literature, this tuning was performed by substituting biaryls in 2 and 2' position with different sterically demanding groups [18][19][20][21][22][23][24] or by interlinking the two positions with chains of different lengths. 3,4,8,25 By substituting biaryls in 2,2' position differently from the 6,6' 40 position not only the torsion angle is adjusted but also axial chirality is introduced which opens up a variety of new potential applications like POLED (based on circular polarized luminescence), 26 or new powerful ligands for enantioselective catalytic processes. Although enantioselective syntheses of axial 45 chiral biphenyls are known, the preparation is up to date synthetically challenging, time consuming and mostly limited to in 2,2',6,6' crowded biphenyl compounds.…”