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Alkyl- π engineering in state control toward versatile optoelectronic soft materials

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ABSTRACT

Organic π-conjugated molecules with extremely rich and tailorable electronic and optical properties are frequently utilized for the fabrication of optoelectronic devices. To achieve high solubility for facile solution processing and desirable softness for flexible device fabrication, the rigid π units were in most cases attached by alkyl chains through chemical modification. Considerable numbers of alkylated-π molecular systems with versatile applications have been reported. However, a profound understanding of the molecular state control through proper alkyl chain substitution is still highly demanded because effective applications of these molecules are closely related to their physical states. To explore the underlying rule, we review a large number of alkylated-π molecules with emphasis on the interplay of van der Waals interactions (vdW) of the alkyl chains and π–π interactions of the π moieties. Based on our comprehensive investigations of the two interactions’ impacts on the physical states of the molecules, a clear guidance for state control by alkyl-π engineering is proposed. Specifically, either with proper alkyl chain substitution or favorable additives, the vdW and π–π interactions can be adjusted, resulting in modulation of the physical states and optoelectronic properties of the molecules. We believe the strategy summarized here will significantly benefit the alkyl-π chemistry toward wide-spread applications in optoelectronic devices.

No MeSH data available.


(a) Chemical structure of molecular liquids 30–33 containing branched alkyl chains. (b) Cryo-TEM image of micelles of 20 in n-decane; inset, proposed aggregate structure of 20. (c) Left: photographs showing the isotropic and gelled states that arise on dissolving 30 in n-decane; right: schematic depictions of the assembled micelles in the isotropic state (up) and gel fibers in the gelled state (below). POM (d) and TEM (e) images for 1:10 molar ratios of C60 and 20 at room temperature; inset of (e) proposed lamellar structure. Reprinted with permission from M J Hollamby et al 2014 Nat. Chem.6 690, © 2014 Macmillan Publishers.
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Figure 23: (a) Chemical structure of molecular liquids 30–33 containing branched alkyl chains. (b) Cryo-TEM image of micelles of 20 in n-decane; inset, proposed aggregate structure of 20. (c) Left: photographs showing the isotropic and gelled states that arise on dissolving 30 in n-decane; right: schematic depictions of the assembled micelles in the isotropic state (up) and gel fibers in the gelled state (below). POM (d) and TEM (e) images for 1:10 molar ratios of C60 and 20 at room temperature; inset of (e) proposed lamellar structure. Reprinted with permission from M J Hollamby et al 2014 Nat. Chem.6 690, © 2014 Macmillan Publishers.

Mentions: C60 derivatives 20 (figure 17) [71] and 30 (figure 23(a)) [17], alkylated with different branched chains, formed unstructured liquid and a disordered amorphous state at room temperature, respectively. However, upon the addition of n-alkanes solvents, n-decane for instance, the two compounds self-assembled into spherical core–shell micelles with an average diameter of 2.5 ± 0.3 nm (figure 23(b)) and into hexagonally packed gel-fibers containing insulated C60 nanowires with cylindrical micelles of 3.2 nm diameter (figure 23(c)), respectively.


Alkyl- π engineering in state control toward versatile optoelectronic soft materials
(a) Chemical structure of molecular liquids 30–33 containing branched alkyl chains. (b) Cryo-TEM image of micelles of 20 in n-decane; inset, proposed aggregate structure of 20. (c) Left: photographs showing the isotropic and gelled states that arise on dissolving 30 in n-decane; right: schematic depictions of the assembled micelles in the isotropic state (up) and gel fibers in the gelled state (below). POM (d) and TEM (e) images for 1:10 molar ratios of C60 and 20 at room temperature; inset of (e) proposed lamellar structure. Reprinted with permission from M J Hollamby et al 2014 Nat. Chem.6 690, © 2014 Macmillan Publishers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036497&req=5

Figure 23: (a) Chemical structure of molecular liquids 30–33 containing branched alkyl chains. (b) Cryo-TEM image of micelles of 20 in n-decane; inset, proposed aggregate structure of 20. (c) Left: photographs showing the isotropic and gelled states that arise on dissolving 30 in n-decane; right: schematic depictions of the assembled micelles in the isotropic state (up) and gel fibers in the gelled state (below). POM (d) and TEM (e) images for 1:10 molar ratios of C60 and 20 at room temperature; inset of (e) proposed lamellar structure. Reprinted with permission from M J Hollamby et al 2014 Nat. Chem.6 690, © 2014 Macmillan Publishers.
Mentions: C60 derivatives 20 (figure 17) [71] and 30 (figure 23(a)) [17], alkylated with different branched chains, formed unstructured liquid and a disordered amorphous state at room temperature, respectively. However, upon the addition of n-alkanes solvents, n-decane for instance, the two compounds self-assembled into spherical core–shell micelles with an average diameter of 2.5 ± 0.3 nm (figure 23(b)) and into hexagonally packed gel-fibers containing insulated C60 nanowires with cylindrical micelles of 3.2 nm diameter (figure 23(c)), respectively.

View Article: PubMed Central - PubMed

ABSTRACT

Organic π-conjugated molecules with extremely rich and tailorable electronic and optical properties are frequently utilized for the fabrication of optoelectronic devices. To achieve high solubility for facile solution processing and desirable softness for flexible device fabrication, the rigid π units were in most cases attached by alkyl chains through chemical modification. Considerable numbers of alkylated-π molecular systems with versatile applications have been reported. However, a profound understanding of the molecular state control through proper alkyl chain substitution is still highly demanded because effective applications of these molecules are closely related to their physical states. To explore the underlying rule, we review a large number of alkylated-π molecules with emphasis on the interplay of van der Waals interactions (vdW) of the alkyl chains and π–π interactions of the π moieties. Based on our comprehensive investigations of the two interactions’ impacts on the physical states of the molecules, a clear guidance for state control by alkyl-π engineering is proposed. Specifically, either with proper alkyl chain substitution or favorable additives, the vdW and π–π interactions can be adjusted, resulting in modulation of the physical states and optoelectronic properties of the molecules. We believe the strategy summarized here will significantly benefit the alkyl-π chemistry toward wide-spread applications in optoelectronic devices.

No MeSH data available.