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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.

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(a) Chemical structure of an OPV-functionalized bisurea 8. (b) AFM phase images of 8 spin-coated on HOPG from a methylcyclohexane dispersion; inset shows a high-resolution image. Photographs of the self-supporting decane gel of 8 deposited on the glass substrate taken under visible light (c) and 365 nm UV light (d). Reprinted with permission from S Yagai et al 2008 Chem. Eur. J.14 5246, © 2008 John Wiley & Sons.
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Figure 10: (a) Chemical structure of an OPV-functionalized bisurea 8. (b) AFM phase images of 8 spin-coated on HOPG from a methylcyclohexane dispersion; inset shows a high-resolution image. Photographs of the self-supporting decane gel of 8 deposited on the glass substrate taken under visible light (c) and 365 nm UV light (d). Reprinted with permission from S Yagai et al 2008 Chem. Eur. J.14 5246, © 2008 John Wiley & Sons.

Mentions: The group of Yagai synthesized a series of alkylated π molecules attached by hydrogen bonding units, which gave rise to numerous functional optoelectronic materials [60–62]. For example, consider an oligo(p-phenylene vinylene)- (OPV) functionalized bisurea, 8 (figure 10(a)) [60], as a consequence of the cooperative π–π interactions of OPV units, vdW interactions of the alkyl chains and hydrogen bonding from the urea units, the molecule possessed a very high supramolecular polymerization ability and formed noncovalent polymers with intertwined fibrous structures by simply spin-coating it in a methylcyclohexane solution on a HOPG substrate (figure 10(b)). To compare, in various organic solvents, such as n-decane, CH2Cl2 and THF, compound 8 showed a tendency to gelate, giving rise to fluorescent gels (figures 10(c)–(d)). Such a strong aggregation ability of 8 in a solution is significant for its applications as solution-incorporated soft materials.


Alkyl- π engineering in state control toward versatile optoelectronic soft materials
(a) Chemical structure of an OPV-functionalized bisurea 8. (b) AFM phase images of 8 spin-coated on HOPG from a methylcyclohexane dispersion; inset shows a high-resolution image. Photographs of the self-supporting decane gel of 8 deposited on the glass substrate taken under visible light (c) and 365 nm UV light (d). Reprinted with permission from S Yagai et al 2008 Chem. Eur. J.14 5246, © 2008 John Wiley & Sons.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 10: (a) Chemical structure of an OPV-functionalized bisurea 8. (b) AFM phase images of 8 spin-coated on HOPG from a methylcyclohexane dispersion; inset shows a high-resolution image. Photographs of the self-supporting decane gel of 8 deposited on the glass substrate taken under visible light (c) and 365 nm UV light (d). Reprinted with permission from S Yagai et al 2008 Chem. Eur. J.14 5246, © 2008 John Wiley & Sons.
Mentions: The group of Yagai synthesized a series of alkylated π molecules attached by hydrogen bonding units, which gave rise to numerous functional optoelectronic materials [60–62]. For example, consider an oligo(p-phenylene vinylene)- (OPV) functionalized bisurea, 8 (figure 10(a)) [60], as a consequence of the cooperative π–π interactions of OPV units, vdW interactions of the alkyl chains and hydrogen bonding from the urea units, the molecule possessed a very high supramolecular polymerization ability and formed noncovalent polymers with intertwined fibrous structures by simply spin-coating it in a methylcyclohexane solution on a HOPG substrate (figure 10(b)). To compare, in various organic solvents, such as n-decane, CH2Cl2 and THF, compound 8 showed a tendency to gelate, giving rise to fluorescent gels (figures 10(c)–(d)). Such a strong aggregation ability of 8 in a solution is significant for its applications as solution-incorporated soft materials.

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.


Related in: MedlinePlus