Topological Control of Columnar Stacking Made of Liquid‐Crystalline Thiophene‐Fused Metallonaphthalocyanines

Abstract

The spontaneous organization of two‐dimensional polyaromatic molecules into well‐defined nanostructures through noncovalent interactions is important in the development of organic‐based electronic and optoelectronic devices. Two regioisomers of thiophene‐fused zinc naphthalocyanines ZnTNcendo and ZnTNcexo have been designed and synthesized to obtain photo‐ and electroactive liquid crystalline materials. Both compounds exhibited liquid crystalline behavior over a wide temperature range through intermolecular π–π interactions and local phase segregation between the aromatic cores and peripheral side chains. The structural differences between ZnTNcendo and ZnTNcexo affected the stacking mode in self‐assembled columns, as well as symmetry of the two‐dimensional rectangular columnar lattice. The columnar structure in liquid crystalline phase exhibited an ambipolar charge‐transport behavior.

Butterfly‐like Shape Liquid Crystals Based Fused‐Thiophene as Unidimensional Ambipolar Organic Semiconductors with High Mobility

“…In this context, the results obtained here compared quite well with those of other columnar LC thiophene derivatives reported in the literature, and thus are quite relevant. Indeed, one of the highest TOF mobility was reported for a thiophene-fused phthalocyanine-Zn complex (10 À 2 cm 2 V À 1 s À 1 ), [16] whereas a X-shaped pyrene-oligothiophenes [45] showed mobility in the range from 10 À 4 to 10 À 5 cm 2 V À 1 s À 1 , but could be largely improved to 10 À 3 cm 2 V À 1 s À 1 when mixed in a physical gel blend. Let us as well mention some ambipolar octupolar πconjugated columnar LCs with a mobility in the range 10 À 2 -10 À 3 cm 2 V À 1 s À 1 .…”

“…[12] Columnar mesophases are primarily obtained by the selfassembly of highly symmetrical disc-shaped molecules such as the archetypical polycyclic aromatics of the benzoid family e. g. triphenylenes, [13] hexabenzocoronenes, [14] or the heterocyclic porphyrine and phthalocycanine derivatives. [15,16] They can also be induced by other molecular systems with shapes deviating substantially from a disc such as, just to cite but a few examples, tapered, [17] polycatenar, [18] star- [19] and bent-shaped [20] mesogens. However, the former systems possess generally higher charge carrier transport properties [21] than in columns made of these non-discoid mesogens, [22] whose small size of their aromatic cores with limited conjugation and π-overlap, associated with rotational symmetry around the long axis, may be detrimental to the optimization of molecular interactions and stacking.…”

Ditriphenylenothiophene butterfly-shape liquid crystals. The influence of polyarene core topology on self-organization, fluorescence and photoconductivity

“…Despite numerous studies, the effect of positional/regio-isomerism on the physical properties of sulfurcontaining p-conjugated disc-like polyaromatics has been rarely investigated to date. [30][31][32][33] For some polycyclic thiophene-fused DLCs reported, not only the mesomorphous properties (phase type, temperature ranges, and transition temperatures) and air/ thermal/photo/chemical stabilities, but also the fluorescence behavior and photoconductivity/device performances were found to be strongly controlled by the relative orientations of the sulfur atoms, which also significantly alter p-p stacking and sulfur-involved intermolecular interactions between isomers. Investigation of the molecular isomerism of thiophene-based DLCs therefore appears as an important and inevitable step in the development of organic-based electronic and optoelectronic devices with optimized performances.…”

“…Similarly, thiophene-fused discotic liquid crystals (DLCs) 16–33 consisting of a π-extended polyaromatic core surrounded by peripheral alkyl chains also display remarkable assets: they spontaneously self-organize into stable columnar mesophases and show unidimensional μ values ranging from 10 −4 up to 10 −2 cm 2 V −1 s −1 . 21,34–37 While developing such DLC-based semiconducting systems, various strategies, including, notably, the extension of π-conjugated polyaromatic cores, 38,39 molecular dynamic motion controlled by intermolecular hydrogen-bonding, 40,41 and nanosegregation by hydrophilic/hydrophobic 6 and fluorophilic/fluorophobic interactions, 42 have been largely considered and successfully applied to promote and enhance charge carrier mobility.…”