Preparation of novel porphyrin nanomaterials based on the
pH-responsive shape evolution of porphyrin microspheres
Wenbo Zhang1(11229034), Lingbo Xing1, Haisheng Wang1, Xiujun Liu2,Yaqing Feng2 and Changyou Gao1*
1.MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science
and Engineering, Zhejiang University, Hangzhou 310027, China
2.School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
*E-mail address: [email protected]
Introduction
Environmental-responsive self-assembly has been widely researched
recently, which can change the shape or properties of the materials.
However, stimuli-triggered shape evolutions of organic microspheres
have rarely been reported so far. Here a novel kind of porphyrin
microspheres (PAH-g-Por MPs) were prepared. The PAH-g-Por MPs
transformed into four different kinds of novel one-dimensional selfassembly structures (NRs@pH1, NRs@pH2, NRs@pH3 and
WSs@pH4) after incubation in pH1, pH2, pH3 and pH4 hydrochloric
acid, respectively. The rate and degree of hydrolysis had an important
effect on formation of the three structures. The MPs and the four selfassembled structures emitted stable red fluorescence, which will find
potential applications in different fields.
a
1668
a
1631
1631
b
1d
1h
7d
1d
4d
40 d
7d
3500 3000
1500
3500 3000
1000
1500
-1
1000
-1
Wavenumber (cm )
Wavenumber (cm )
Figure 4. FTIR spectra of PAH-g-Por MPs after being incubated in (a) pH 1 and (b)
pH 4 HCl for different time as noted in the figure, respectively.
Table 1. The molar ratio of Por to PAH repeating unit ([PAH]) and the release ratio
of [PAH] calculated according to the elemental analysis results.
Reaction pH value
pH 1
Time (d)
EDTA
PAH-doped CaCO3
PAH-g-Por-doped CaCO3
1
Por-CHO )
c
1 μm
e
1668(-CHO) 1631(-C=N-)
Por-CHO
1μm
d
PAH
3500
10 μm
1μm
3000
1500
1000
-1
Wavenumber(cm )
Figure 2. (a) SEM (inset, higher magnification), (b) TEM, (c) cross section
(ultramicrotomy) TEM and (d) CLSM images of PAH-g-Por microspheres. (e)
FTIR spectra of Por-CHO, PAH, and PAH-g-Por MPs.
a
b
30
7
40
16.2
11.9
14.4
8.9
9
[PAH] release ratio (%)
37.5 46.2
58.6
45
24.9
38.3
0
1.1
58
0d
3d
7d
14d
21d
700
750
0d
3d
7d
21d
40d
b
800
650
c
d
700
750
800
Wavelength ( nm )
Wavelength ( nm )
PAH-Por MPs
5 μm
7
21.5
650
b
30
PAH-g-Por MPs
Figure 1. (a) Schematic illustration of formation and decomposition of PAH-gPor; (b) Structure evolution and formation of various nano-structures of PAH-gPor microspheres at different pH values.
a
30
8.9 14.3 16.6 21.2
Fluorescence Intensity ( a.u. )
PAH
7
pH 4
Por: [PAH] (%)
a
(
4
pH 3
Fluorescence Intensity ( a.u. )
b
0
pH 2
Figure 5. Fluorescence spectra of PAH-g-Por MPs after being incubated in (a) pH
1 and (b) pH 4 HCl for different time as noted in the figure, respectively. The
excitation wavelength is 420 nm.
Conclusion
The pH-responsive decomposition-assembly of PAH-g-Por MPs leads
to four kinds of novel porphyrin nanomaterials, which haven’t been
reported for Por-CHO. The rate and degree of Schiff base hydrolysis
have an important effect on the formation of the four structures.
NRs@pH1, NRs@pH2 and NRs@pH3 are all composed of the released
Por-CHO and the unhydrolyzed PAH-g-Por due to the partial hydrolysis
of the Schiff base. At pH4, the PAH-g-Por MPs undergo a shape
evolution process without hydrolysis to produce WSs@pH4.
1 μm
Acknowledgements
2μm
e
2 μm
f
500 nm
g
1 μm
10 μm
h
1μm
2μm
2 μm
2 μm
5 μm
Figure 3. (a-d) SEM and (e-h) TEM images (inset, higher magnification) of
decomposition-assembly structures of PAH-g-Por MPs after treatment in (a,e)
pH 1, (b,f) pH 2, (c,g) pH 3 and (d,h) pH 4 HCl for 7 d, 7d, 30d and 40 d,
respectively .
This work is supported by the Ph. D. Programs Foundation of Ministry of
Education of China (20110101130005) and the Natural Science
Foundation of China (51120135001).
References
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2011, 5: 3930–3936.