Discotic liquid crystals of transition metal complexes 52: Synthesis and homeotropic alignment of liquid crystalline phthalocyanine-fullerene dyad bridged by vanillin

Abstract

ABSTRACT:We have synthesized a novel liquid crystalline phthalocyanine(Pc)-fullerene(C 60 ) dyad (C 14 S) 6 PcCu-VAN-C 60 (3a) bridged by an inexpensive natural product of vanillin (VAN), instead of the previous long n-alkylene chain spacer. We have also synthesized a comparative dyad (C 14 S) 6 PcCu-OPh-C 60 (3b) bridged by p-hydroxybenzaldehyde (OPh), in order to investigate the influence of the methoxy group in the vanillin moiety on homeotropic alignment between two glass plates.Very interestingly, homeotropic alignment could be observed only for the dyad (C 14 S) 6 PcCu-VAN-C 60 (3a) having a methoxy group in the vanillin moiety, whereas it could not be observed for the dyad (C 14 S) 6 PcCu-OPh-C 60 (3b) having no methoxy group at the phenoxy group. It is very noteworthy that such a slight difference in these molecular structures between 3a and 3b becomes a crucial point to show the homeotropic alignment. Each of the dyads, 3a and 3b, showed two hexagonal ordered columnar (Col ho ) mesophases. Each of the Col ho mesophases in 3a and 3b gave an additional very strong reflection peak named as Peak H in a very low angle region of the SAXS (small angle X-ray scattering) pattern.Peak H could be established, from two different SAXS measurement methods, as one pitch in a helical structure of the fullerenes around the Pc column.

Metal Phthalocyanine−Fullerene Dyads: Promising Lamellar Columnar Donor−Acceptor Liquid Crystal Phases

“…Phthalocyanines and porphyrins, which show absorption of the visible light over a broad portion of the solar spectrum and are well known discotic mesogens with high charge carrier mobilities, have been subsequently attached to the broadly used, excellent electron acceptor, fullerene C60 . Many of these systems have been claimed to be columnar liquid crystals with helically arranged fullerenes in the periphery . High ambipolar and balanced hole and electron mobilities, long‐lived charge separated states, and facile homeotropic alignment have been reported .…”

“…Many of these systems have been claimed to be columnar liquid crystals with helically arranged fullerenes in the periphery . High ambipolar and balanced hole and electron mobilities, long‐lived charge separated states, and facile homeotropic alignment have been reported . Indeed, these properties would be perfect for the production of photovoltaic cells, however, to the best of our knowledge no PV cell with aligned LC phthalocyanine‐fullerene dyads has been reported today.…”

Fulleren‐gefüllte Flüssigkristall‐Sterne: Ein supramolekularer Klick‐Mechanismus zur Bildung von maßgeschneiderten Donor‐Akzeptor‐Strukturen

“…Wirs tellen einen solchen supramolekularen "Klick"-Vorgang vor, der an den Kugelarretierungs-Mechanismus erinnert, wobei die Positionen der sternfçrmigen Zinkphthalocyanine (ZnPc) 2 und 3 (Abbildung 1) mit regelmäßigen p-p-Abständen bezüglich des Zentrums der Kolumne fixiert werden. [10,11] Diese Formamphiphile segregieren aufgrund der großen Morphologieunterschiede zwischen den sphärischen C 60 Letztere wurden analog zu den bekannten Derivaten mit aliphatischen Ketten synthetisiert. [5] In der Mischung füllt das C 60 den Freiraum zwischen den konjugierten Armen, was zur Entstehung einer gefüllten flüssigkristallinen Phase mit ZnPc-Donoren führt, die von einer Fulleren-Akzeptor-Quadrupelhelix umgeben ist.…”

“…[9] Die Donor-Akzeptor-Kombinationen aus Fullerenen und Phthalocyaninen bzw.P orphyrinen wurden kürzlich als vielversprechende Materialien im Bezug auf die zukünftige Anwendung in der organischen Photovoltaik bezüglich der Ladungsgenerierung sowie der Tr ansporteigenschaften genau untersucht. [10,11] Diese Formamphiphile segregieren aufgrund der großen Morphologieunterschiede zwischen den sphärischen C 60 Letztere wurden analog zu den bekannten Derivaten mit aliphatischen Ketten synthetisiert. [12,14] Die Verbindungen 6a,b wurden zu den ZnPc-Derivaten 1 und 2 in mittelmäßigen Ausbeuten von 22-27 %k onvertiert.…”

Fullerene‐Filled Stilbene Stars: The Balance between Isolated C60 Helices and 3D Networks in Liquid‐Crystal Self‐Assemblies

“…[11] Often, dyads with triphenylene,p orphyrin, or phthalocyanine donors have been studied to generate photovoltaic systems. [12][13][14][15][16][17] It has been suggested that the incommensurate packing distance of fullerenes (1.03 nm) andd iscotics (0.34 nm) were compensated by helical arrangements of the fullereneu nits. Similar to the star-shaped mesogens SnFm,t hese liquid crystals can be describeda ss hape amphiphiles, [1] for which the drivingf orce towardst he helical assembly is the nanosegregation of fullerenes and the efficient space-filling of the entire system.T he stilbenoid scaffold has been chosen becausei tis shape-persistent: the overall star topology remains, although differentc onformers can be realized by rotationa boutt he single bonds betweent he phenyl groups and double bonds.…”