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Alkyl- π engineering in state control toward versatile optoelectronic 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.

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(a) Chemical structures of C60 derivatives 13–18 containing linear alkyl chains. (b) Photographs of room-temperature C60 liquids 14, 15 and 17. Reprinted with permission from T Michinobu et al 2006 J. Am. Chem. Soc. 128 10384, © 2006 American Chemical Society. (c) Relationship between the melting point and alkyl chain length of C60 derivatives 13–18, redrawn from [86]. (d) TEM image of the CdSe NCs/17 composite; inset, high-resolution TEM image of a CdSe NC. (e) Photoelectrochemical activity of solvent-free CdSe NCs/17 composite films on glass coated with fluorine-doped tin oxide containing 17 alone (black), 25 wt% CdSe NCs (blue) and CdSe NCs alone (red) under blue light (at 480 nm) illumination. Reprinted from [87].
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Figure 15: (a) Chemical structures of C60 derivatives 13–18 containing linear alkyl chains. (b) Photographs of room-temperature C60 liquids 14, 15 and 17. Reprinted with permission from T Michinobu et al 2006 J. Am. Chem. Soc. 128 10384, © 2006 American Chemical Society. (c) Relationship between the melting point and alkyl chain length of C60 derivatives 13–18, redrawn from [86]. (d) TEM image of the CdSe NCs/17 composite; inset, high-resolution TEM image of a CdSe NC. (e) Photoelectrochemical activity of solvent-free CdSe NCs/17 composite films on glass coated with fluorine-doped tin oxide containing 17 alone (black), 25 wt% CdSe NCs (blue) and CdSe NCs alone (red) under blue light (at 480 nm) illumination. Reprinted from [87].

Mentions: During the investigation of alkylated-C60 derivatives, our group found that compounds 14, 15 and 17 substituted with the 2,4,6-tris(alkyloxy)phenyl group (figure 15(a)) exhibited a liquid phase at room temperature with melting points of 13.7, −36.5 and 4.5 °C, respectively (figure 15(b)) [85]. The formation of such a room-temperature liquid state could be attributed to the 2,4,6-substitution pattern, which disturbed the π–π interactions of the C60 units based on the independent spreading of the three chains acting as an effective steric stabilizer of individual C60 moieties.


Alkyl- π engineering in state control toward versatile optoelectronic soft materials
(a) Chemical structures of C60 derivatives 13–18 containing linear alkyl chains. (b) Photographs of room-temperature C60 liquids 14, 15 and 17. Reprinted with permission from T Michinobu et al 2006 J. Am. Chem. Soc. 128 10384, © 2006 American Chemical Society. (c) Relationship between the melting point and alkyl chain length of C60 derivatives 13–18, redrawn from [86]. (d) TEM image of the CdSe NCs/17 composite; inset, high-resolution TEM image of a CdSe NC. (e) Photoelectrochemical activity of solvent-free CdSe NCs/17 composite films on glass coated with fluorine-doped tin oxide containing 17 alone (black), 25 wt% CdSe NCs (blue) and CdSe NCs alone (red) under blue light (at 480 nm) illumination. Reprinted from [87].
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 15: (a) Chemical structures of C60 derivatives 13–18 containing linear alkyl chains. (b) Photographs of room-temperature C60 liquids 14, 15 and 17. Reprinted with permission from T Michinobu et al 2006 J. Am. Chem. Soc. 128 10384, © 2006 American Chemical Society. (c) Relationship between the melting point and alkyl chain length of C60 derivatives 13–18, redrawn from [86]. (d) TEM image of the CdSe NCs/17 composite; inset, high-resolution TEM image of a CdSe NC. (e) Photoelectrochemical activity of solvent-free CdSe NCs/17 composite films on glass coated with fluorine-doped tin oxide containing 17 alone (black), 25 wt% CdSe NCs (blue) and CdSe NCs alone (red) under blue light (at 480 nm) illumination. Reprinted from [87].
Mentions: During the investigation of alkylated-C60 derivatives, our group found that compounds 14, 15 and 17 substituted with the 2,4,6-tris(alkyloxy)phenyl group (figure 15(a)) exhibited a liquid phase at room temperature with melting points of 13.7, −36.5 and 4.5 °C, respectively (figure 15(b)) [85]. The formation of such a room-temperature liquid state could be attributed to the 2,4,6-substitution pattern, which disturbed the π–π interactions of the C60 units based on the independent spreading of the three chains acting as an effective steric stabilizer of individual C60 moieties.

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