Ultalong nanowires self-assembled from a [b]-bisphenanthrene-fused azadipyrromethene

Article abstract of DOI:10.1016/j.cclet.2020.08.047

The 1D microwires based on π-extended azaBODIPY were successfully prepared and characterized for the first time. The bisphenanthrene-fused azaBPP-12C with four hydrophobic chains was prepared through de novo synthesis method involving the Suzuki reaction and subsequent oxidative ring-fused coupling. The microwires and aggregation behavior were studied using SEM, XRD and absorption spectroscopy. Finally, an H-type aggregation was confirmed in the solution process.

Full text of DOI:10.1016/j.cclet.2020.08.047

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CCLET 5824 No. of Pages 4
Chinese Chemical Letters xxx (2019) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Communication
Ultalong nanowires self-assembled from a [b]-bisphenanthrene-fused
azadipyrromethene
b,
Wanle Shenga, Zhangcui Wanga, Erhong Haob, , Lijuan Jiao
*
*
a
Department of Chemistry, Bengbu Medical College, Bengbu 233030, China
b
The Key Laboratory of Functional Molecular Solids, Ministry of Education, School of Chemistry and Materials Science, Anhui Normal University, Wuhu
241002, China
A R T I C L E I N F O
A B S T R A C T
Article history:
Received 5 July 2020
Received in revised form 7 August 2020
Accepted 26 August 2020
Available online xxx
The 1D microwires based on
p-extended azaBODIPY were successfully prepared and characterized for
the first time. The bisphenanthrene-fused azaBPP-12C with four hydrophobic chains was prepared
through de novo synthesis method involving the Suzuki reaction and subsequent oxidative ring-fused
coupling. The microwires and aggregation behavior were studied using SEM, XRD and absorption
spectroscopy. Finally, an H-type aggregation was confirmed in the solution process.
© 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
Published by Elsevier B.V. All rights reserved.
Keywords:
AzaBODIPY
Self-assembly
H-aggregation
Nanowire
p
-Extended
Organic compounds with polycyclic aromatic hydrocarbons
generally show superior optoelectronic and self-assembling
properties due to the interaction between molecules [1–3].
their highly electron-deficient conjugation core skeletons with
large dipole moments are ideal features for the promising organic
electronics and self-assembly properties [25–27]. For example, the
amphiphilic azaBODIPY molecule can self-assemble into globular
nanoparticles and elongated nanorods by J-type aggregation mode
[28–30]. The azaBODIPY molecule introduced with phosphoric
acid can self-assemble to form nanosphere shells [31]. However,
due to the limitation of the synthesis, there are few reports about
p-p
The self-assembly process is depending on molecular structure,
which could be manipulated through molecular structure engi-
neering [4–6]. This has been well demonstrated by the extensively
studied hexabenzocoronene (HBC, Fig. 1) and their heteroatom-
doped derivatives system, such as forming one dimensional (1D)
micro- or nanowires [7,8], nanotubes [9–11], two dimensional (2D)
nanosheets [12,13], which show great potential in electronic
devices, such as organic field effect transistors and photodetectors
[14,15].
the p-extended conjugated azaBODIPY. Until recently, we reported
[a]- and [b]-bisphenanthrene-fused azaBODIPYs (azaBPP, Fig. 1)
through oxidative aromatic coupling and palladium catalyst C–H
activation reaction [32–35]. These
p-extended azaBODIPY mole-
Boron dipyrromethene dyes (BODIPYs) and their derivatives, as
an increasingly valuable class of fluorophores, have been devel-
oped through various modification approaches [16–20]. Replacing
the meso carbon atom of BODIPY by nitrogen atom to form
azaBODIPY dyes (Fig. 1), which were first reported by O’Shea et al.
have received extensive research interests lately due to their
excellent stabilities (associated with their rigid structures) and
their remarkable optic and electronic properties, especially the
tunable deep-red to NIR absorptions/emissions [21–24]. Indeed,
cules not only exhibit excellent near infrared optical activity and
interesting electronics properties, but also provide an opportunity
to produce discrete (isolable) nanostructures through self-
assembly. Despite the effects toward controlling and tuning the
morphology of related porphyrinoids [36–38] and the above HBC
molecules, the facile synthesis of well-defined, large nanostruc-
tures with NIR absorption over 800 nm, which have promising
applications in important areas such as sensors, phototheranostic
agents, and solar power, is still limited.
Herein, we synthesized a [b]-bisphenanthrene-fused azaBO-
DIPY containing four long hydrophobic chains on the periphery
(azaBPP-12C). Combined the
azaBPP-12C can be self-assembled into one-dimensional
p-p and side chain interactions,
* Corresponding authors.
E-mail addresses: haoehong@ahnu.edu.cn (E. Hao), jiao421@ahnu.edu.cn
microwires through the solution process. The microwires were
(L. Jiao).
https://doi.org/10.1016/j.cclet.2020.08.047
1001-8417/© 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: W. Sheng, et al., Ultalong nanowires self-assembled from a [b]-bisphenanthrene-fused azadipyrromethene,
Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.08.047

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173,800 L molÀ1 cmÀ1, which is double greater than that of 1
(74,100 L molÀ1 cmÀ1).
The self-assembly behaviors of azaBPP-12C in solution was
monitored by the absorption spectral measurement. Initially,
azaBPP-12C keeps the original characteristic absorption peak in
THF (Fig. 3a). Progressively increasing the volume fraction of water,
as a poor solvent, in THF does not affect its spectrum until the
solution consists of 70% water. The intensity of the main absorption
band was decreased greatly, while the absorption at shorter
wavelength became enhanced. No red-shifted absorption band
was observed, which indicated that an H-aggregation of azaBPP-
12C was formed during the aggregationprocess [39,40]. Continuing
to increase the fraction of water to 90%, the absorption intensity of
the short wavelength was increased with a slight lift up around
850 nm, which may be due to the extended aggregate states. The
same aggregation process was also detected in ethanol solution
(Fig. 3b). As time goes on, the absorption below 790 nm was
gradually decreased, while the absorption at shorter wavelength
Fig. 1. Core structures of hexabenzocoronene (HBC), azadipyrromethenes boron
difluoride (azaBODIPY) and [b]-bisphenanthrene-fused azaBODIPYs (azaBPP).
characterized using scanning electron microscope (SEM) and X-ray
diffraction (XRD), the length can reach hundreds of microns. The
aggregation behavior of azaBPP-12C in solution was confirmed as
H-type aggregation by absorption spectroscopy.
became enhanced. These results indicate the dominant role of p-p
interaction between the molecules of azaBPP-12C.
[b]-PhenanthroazaBODIPY azaBPP-12C with four side chain
was synthesized in Scheme 1. 1,3,5,7-Tetra-(4-dodecyloxyphenyl)
azaBODIPY 3, as the key starting material with long chain installed
initially, was generated in an overall yield of 30% in three steps
(Scheme S1 in Supporting information) from commercially
available 4-dodecyloxybenzaldehyde and 4-dodecyloxyacetophe-
none. After bromination, the dibromoazaBODIPY 2 was then
applied in the Suzuki coupling reaction with 4-tert-butylphenyl-
boronic acid to afford the corresponding azaBODIPY 1 in 77% yield
(Scheme 1). The subsequent oxidative ring-fusion reaction with 10
equiv. of FeCl3 in CH2Cl2/CH3NO2 at room temperature afforded
target product azaBPP-12C successfully in high yield.
The face-to-face arrangement of
p-p interaction between the
molecules typically guarantees the formation of 1D materials [41].
The morphology of the aggregates formed was then examined by
scanning electron microscopy (SEM). Initially, we used the method
of poor solvent mixing to prepare the aggregates. At room
temperature, methanol continuously mixed into the chloroform
solution of azaBPP-12C. As the poor solvent methanol continu-
ously increased, the solubility of the mixed solvent to azaBPP-12C
was decreased. Under
p-p intermolecular interaction and alkyl
chain interaction, one-dimensional nanowires were indeed
gradually formed (Fig. S1 in Supporting information). However,
the speed of poor solvent mixing may be too fast, the nanowires
formed by this method have great defects.
Finally, the well-ordered 1D nanowires of azaBPP-12C were
precipitated by cooling hot saturated solution. A suspension of
azaBPP-12C in MeOH/THF (ratio: 1/2) was heated to form a
homogeneous solution. Then the solution was cooled to room
temperature slowly, allowing the molecules to self-assemble. The
The UV–vis absorption as well as fluorescence spectra of 1 and
azaBPP-12C in chloroform (Fig. 2) show all of the typical spectral
features of substituted azaBODIPY and [b]-phenanthroazaBODIPYs
reported in the literatures [33,34]. Compound 1 exhibits absorp-
tion band around 580À730 nm, with a maximum peak at 657 nm
and the corresponding emission maximum at 683 nm (f = 0.25).
After the cyclization, the absorption bands of azaBPP-12C undergo
significant red shifts to 700À830 nm, with the maximum
absorption peak at 790 nm. The molar extinction coeffient
value of the ring-fusion compounds azaBPP-12C reaches
nanowires obtained in MeOH/THF mixed solvent are around 1
mm
in width and hundreds of micrometers in length (Figs. 4a-b and
Scheme 1. Synthesis of [b]-Bisphenanthrene-Fused AzaBODIPYs azaBPP-12C.
Please cite this article in press as: W. Sheng, et al., Ultalong nanowires self-assembled from a [b]-bisphenanthrene-fused azadipyrromethene,
Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.08.047

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3
Fig. 2. Absorption (Abs) and fluorescence (FL) spectra of compounds 1 and azaBPP-
12C in chloroform (5 Â10À6 mol/L).
Fig. 3. Spectroscopic changes observed during aggregation for azaBPP-12C: (a)
Evolution of the absorption spectrum as the water content increased from 0 to 90%
(v/v) in THF/water mixture (4 Â10À6 mol/L). (b) Evolution of the absorption
spectrum in ethanol at different aging times: from 0 to 30 min (3 Â 10À6 mol/L).
Fig. S2 in Supporting information). The microwires were further
characterized by the X-ray diffraction analysis. The first and second
diffraction peaks (d-spacing = 21.8 and 17.0 Å) are assigned to the
edge-to-edge distances between adjacent azaBPP-12C molecules
at the long and short axis directions (Fig. 4g). The broad diffuse
scattering was observed in the middle-angle region (d-spacing
=7.1 Å), which is characteristic of the liquid-like order of the
hydrocarbon chains. Combined with absorption spectral results,
these data indicated that the molecules adopt face to face
arrangement. A one-dimensional columnar arrangement model
was proposed (Fig. 4h). The diffraction peaks in the high-angle
region (d-spacing = 4.3 and 4.4 Å) were assigned to the periodic
correlations of the cores along the columns.
Fig. 4. (a, b) SEM images (a, scale bar: 50
m
m; b, scale bar: 1
m
m) and (g) XRD
pattern of the nanowires grown from 1:2 MeOH:THF solvent. (c, d) SEM images of
the nanowires grown from n-hexane (scale bar: c, 50 m; d, 1 m). (e. f) SEM
images of the nanowires grown from 1,4-dioxane (scale bar: e, 50 m; f,10 m). (h)
m
m
m
m
The proposed model of the columnar stacking structure for azaBPP-12C.
Declaration of competing interest
The authors declare that they have no known competing
financial interests or personal relationships that could have
appeared to influence the work reported in this paper.
When the solvent is changed from MeOH/THF mixed solvent to
n-hexane or 1,4-dioxane, respectively, similar nanowires were also
observed in both solvents using the same method (Figs. 4c-f).
However, the nanowires obtained in hexane are much thinner,
with a width around 500 nm, while the nanowires obtained in 1,4-
Acknowledgments
This work is supported by the National Nature Science
Foundation of China (Nos. 21672006, 21672007, 21871006),
Laboratorial Open Fund of Ministry of Education of Anhui Normal
University (No. FMS201914), and Natural Science Research Fund of
BengBu Medical College (No. BYKY2019005ZD).
dioxane are thicker and more rigid, with a width around 2
mm. In
addition, these nanowires obtained in both 1,4-dioxane and n-
hexane look softer compared to those obtained in MeOH/THF
mixed solvent. These changes in the morphology of self-assembled
nanoscale aggregates indicated the solvent effect on the formation
of self-assembled nanostructures of azaBPP-12C molecules.
In summary, a [b]-bisphenanthrene-fused azaBODIPY with four
side chain was prepared through the de novo synthesis method.
Appendix A. Supplementary data
Supplementarymaterialrelatedtothisarticlecanbefound, inthe
online version, at doi:https://doi.org/10.1016/j.cclet.2020.08.047.
This
and emission in NIR regionwith maximum peaks up to 793 nm and
810 nm, respectively. Due to the enhanced interaction,
p-extended azaBODIPY shows strong, red-shifted absorption
References
p-p
azaBPP-12C adopted H-aggregation during the aggregation. The
ordered 1D microwires are also obtained by solution process and
characterized using SEM and XRD, which are promising materials
for the application in organic devices.
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ꢀ
[1] M. Ste˛pien, E. Gonka, M. Zyłaa, N. Sprutta, Chem. Rev. 117 (2017) 3479–3716.
[2] X. Luo, J. Li, J. Zhao, et al., Chin. Chem. Lett. 30 (2019) 839–846.
[3] Q. Fan, W. Ni, L. Chen, G.G. Gurzadyan, Y. Xiao, Chin. Chem. Lett. DOI: 10.1016/j.
cclet.2020.06.018.
Please cite this article in press as: W. Sheng, et al., Ultalong nanowires self-assembled from a [b]-bisphenanthrene-fused azadipyrromethene,
Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.08.047

G Model
CCLET 5824 No. of Pages 4
4
W. Sheng et al. / Chinese Chemical Letters xxx (2019) xxx–xxx
[4] X. Zhang, Q. Wang, L. Wu, et al., J. Phys. Chem. B 114 (2010) 1233–1240.
[5] M. Al Kobaisi, S.V. Bhosale, K. Latham, A.M. Raynor, S.V. Bhosale, Chem. Rev. 116
(2016) 11685–11796.
[6] Z. Li, S. Chen, C. Gao, et al., J. Am. Chem. Soc. 141 (2019) 19448–19457.
[7] M. Kastler, W. Pisula, D. Wasserfallen, T. Pakula, K. Müllen, J. Am. Chem. Soc.
127 (2005) 4286–4296.
[8] X.Y. Wang, F.D. Zhuang, R.B. Wang, et al., J. Am. Chem. Soc.136 (2014) 3764–3767.
[9] W. Jin, Y. Yamamoto, T. Fukushima, et al., J. Am. Chem. Soc. 130 (2008) 9434–
9440.
[22] K. Burgess, A. Loudet, Chem. Rev. 107 (2007) 4891-4832.
[23] H. Lu, J. Mack, Y. Yang, Z. Shen, Chem. Soc. Rev. 43 (2014) 4778–4823.
[24] Z. Wang, C. Cheng, Z. Kang, et al., J. Org. Chem. 84 (2019) 2732–2740.
[25] H. Wang, Y. Zhang, Y. Chen, et al., Angew. Chem. Int. Ed. 59 (2020) 5185–5192.
[26] Y. Liu, N. Song, Z. Li, L. Chen, Z. Xie, Dye. Pigment. 160 (2019) 71–78.
[27] C. Liu, W. Ding, Y. Liu, H. Zhao, X. Cheng, New J. Chem. 44 (2020) 102–109.
[28] Z. Chen, Y. Liu, W. Wagner, et al., Angew. Chem. Int. Ed. 56 (2017) 5729–5733.
[29] Y. liu, Y. Zhang, F. Fennel, et al., Chem. Eur. J. 24 (2018) 16388–16394.
[30] Y. Chen, X.H. Zhang, D.B. Cheng, et al., ACS Nano 14 (2020) 3640–3650.
[31] M.H.Y. Cheng, K.M. Harmatys, D.M. Charron, J. Chen, G. Zheng, Angew. Chem.
Int. Ed. 58 (2019) 13394–13399.
[10] W. Zhang, W. Jin, T. Fukushima, N. Ishii, T. Aida, J. Am. Chem. Soc. 135 (2013)
114–117.
[11] Y. Liu, W. Zeng, X. Li, W. Jin, D. Zhang, Dye. Pigment. 163 (2019) 553–558.
[12] J. Luo, X. Xu, R. Miao, Q. Miao, J. Am. Chem. Soc. 134 (2012) 13796–13803.
[13] Y. Zhou, M.Y. Zhang, K.H. Gu, et al., Asian J. Org. Chem. 4 (2015) 746–755.
[14] T. Aida, E.W. Meijer, S.I. Stupp, Science 335 (2012) 813–817.
[15] T. Shimizu, W. Ding, N. Kameta, Chem. Rev. 120 (2020) 2347–2407.
[16] Q. Wang, X. Wei, C. Li, Y. Xie, Dye. Pigment. 148 (2018) 212–218.
[17] F. Ma, L. Zhou, Q. Liu, C. Li, Y. Xie, Org. Lett. 21 (2019) 733–736.
[18] G. Su, K. Zhang, F. Sha, et al., Dye. Pigment. 180 (2020)108504.
[19] W. Sheng, F. Lv, B. Tang, E. Hao, L. Jiao, Chin. Chem. Lett. 30 (2019) 1825–1833.
[20] D. Wang, X. Guo, H. Wu, et al., J. Org. Chem. 85 (2020) 8360–8370.
[21] Y. Ge, D.F. O’Shea, Chem. Soc. Rev. 45 (2016) 3846–3864.
[32] J. Cui, W. Sheng, Q. Wu, et al., Chem. Asian J. 12 (2017) 2486–2493.
[33] W. Sheng, J. Cui, Z. Ruan, et al., J. Org. Chem. 82 (2017) 10341–10349.
[34] W. Sheng, Y.Q. Zheng, Q. Wu, et al., Org. Lett. 19 (2017) 2893–2896.
[35] W. Sheng, Y. Wu, C. Yu, et al., Org. Lett. 20 (2018) 2620–2623.
[36] Y. Gao, X. Zhang, C. Ma, X. Li, J. Jiang, J. Am. Chem. Soc.130 (2008) 17044–17052.
[37] Y. Gao, Y. Chen, R. Li, et al., Chem. Eur. J. 15 (2009) 13241–13252.
[38] P. Guo, P. Chen, M. Liu, Langmuir 28 (2012) 15482–15490.
[39] F. Wu
̈rthner, T.E. Kaiser, C.R. Saha-Möller, Angew. Chem. Int. Ed. 50 (2011)
3376–3410.
[40] T. Li, J. Benduhn, Z. Qia, et al., J. Phys. Chem. Lett. 10 (2019) 2684–2691.
[41] Y. Guo, L. Xu, H. Liu, et al., Adv. Mater. 27 (2015) 985–1013.
Please cite this article in press as: W. Sheng, et al., Ultalong nanowires self-assembled from a [b]-bisphenanthrene-fused azadipyrromethene,
Chin. Chem. Lett. (2020), https://doi.org/10.1016/j.cclet.2020.08.047