Supporting Information
Stable and reversible optoelectrical dual-mode data storage based on a
ferrocenlylspiropyran molecule
Ying Ma,1,2 Chengshan Niu,1,2 Yongqiang Wen,1 Guo Li,3 Jingxia Wang,1 Heng Li,1 Shixuan Du,3
Lianming Yang,1 Hongjun Gao,3 and Yanlin Song1,a)
1
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids,
Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190,
China
2
Graduate School of Chinese Academy of Science, Beijing, 100049, China
3
Nanoscale Physics and Device Laboratory, Institute of Physics, Chinese Academy of Sciences, Beijing,
100190, China
a)
To whom correspondence should be addressed: ylsong@iccas.ac.cn
Experimental section
1. Synthesis of SPFc
SPFc was prepared in our laboratory and detailed information on the synthesis will be published
elsewhere in due course.
5’-trans-(2-Ferrocenylvinyl)-3’,3’-dimethyl-1’-(2-hydroxyethyl)-6-nitrospiro[2H-1-benzopyra
n-2,2’-indoline] (SPFc).1H NMR (400 MHz, Acetone-d6): δ 1.22 (s, 3H), 1.32 (s, 3H), 3.27–3.36 (m,
1H), 3.36–3.45 (m, 1H), 3.59–3.70 (m, 1H), 3.70–3.83 (m, 2H), 4.11 (s, 5H), 4.24 (t, J = 1.8 Hz, 2H),
4.48 (d, J = 1.8 Hz, 2H), 6.10 (d, J = 10.4 Hz, 1H), 6.66 (d, J = 8.0 Hz, 1H), 6.78 (d, J = 16.2 Hz, 1H),
6.79 (d, J = 16.3 Hz, 1H), 6.86 (d, J = 9.0 Hz, 1H), 7.18 (d, J = 10.4 Hz, 1H), 7.24 (dd, J1 = 8.0 Hz, J2 =
1
1.7 Hz, 1H), 7.34 (d, J = 1.5 Hz, 1H), 8.05 (dd, J1 = 9.0 Hz, J2 = 2.8 Hz, 1H), 8.08 (d, J = 2.7 Hz, 1H).
C NMR (75 MHz, Acetone-d6): δ 18.8, 24.9, 45.6, 52.0, 59.5, 65.8, 65.9, 67.9, 68.4, 84.1, 106.2, 106.5,
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114.9, 118.4, 118.6, 121.7, 122.1, 122.2, 125.0, 125.7, 126.2, 127.5, 129.6, 136.1, 140.6, 146.2, 159.0.
HRMS (EI-TOF) (m/z) [M+] Calcd for C32H30FeN2O4: 562.1555. Found: 562.1559.
2. General procedure
Photochemical investigation of SPFc dichloromethane solutions was performed using a
high-pressure mercury lamp. The distance between the sample and the lamp was 10 cm; in front of the
sample, filters with maximum wavelength 465 nm and 586 nm were used. Optical characterization was
carried out using a Hitachi U-4100 UV-Vis spectrometer. For information recording, the thin films were
prepared by spin-coating the dichloromethane solution of SPFc and PMMA (Acros Organics) (wt/wt. =
1 : 20) mixture (the concentration of SPFc was 1 × 10-3 M) on to quartz substrate at a spin rate of 800
rpm for 20 s.
By physical vacuum vapor deposition method, the thin film of SPFc (thickness ca. 40 nm) for
macroscopic current-voltage characteristics was deposited on indium tin oxide (ITO) coated glass, and
the thin film for the data storage experiment with STM was deposited on freshly cleaved highly ordered
pyrolytic graphite (HOPG) substrate. The organic molecules were heated to 130 C in a crucible, and
the base vacuum of the deposition system was about 1×10-3 Pa. The macroscopic I-V characteristics
were obtained by scanning the voltage using a Keithley 4200 semiconductor system. The amplitude of
applied voltage was varied to generate a range of I–V characteristics, STM (Solver P47 instrument,
NT-MDT Co.) images shown in this paper were recorded in constant current mode. Electrochemically
etched tungsten tips were used for both STM and scanning tunneling spectroscopy (STS) studies. The
recording experiments were carried out by applying voltage pulses between the tungsten tip and the
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HOPG substrate, and STS was used to probe the local electronic properties of the organic thin films.
When voltage pulses were added, the feedback loop was closed and the STM tip was lifted up a short
distance from the tunneling position to avoid running into the thin film surface. X-ray photoelectron
spectroscopy (XPS) data were obtained with an ESCALab220i-XL electron spectrometer from VG
Scientific using 300W AlKα radiation. The base pressure was about 3×10-9 mbar. The binding energies
were referenced to the C1s line at 284.8 eV from adventitious carbon.
Figures
Fig. S1. Sequential spectral changes of SPFc-doped PMMA film (1:20 by weight) by irradiation with (a)
365 nm UV and then (b) 586 nm visible light. The figure shows that isomerization process of the present
spiropyran do occurs on the solid film.
Fig. S2. (a) The structure and photochemical isomerization of an ordinary spiropyran molecule without
ferrocene and (b) the fatigue resistance of SP-PMMA film (1:20 by weight) under alternative irradiation
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of UV (365 nm, 5 min) and visible light (586 nm, 10 min). The figure shows that the spiropyran without
the modification of ferrocene exhibits a poor fatigue resistance with a great attenuation in absorption
intensity (570 nm) just after 4 cycles.
Fig. S3 The UV-vis spectra of SPFc thin film before and after the application of an electric field. The
figure shows that a slight red shift and intensification of the MLCT absorption band of the SPFc thin
film have occurred owing to the electronic transition.
Fig. S4 The XPS of SPFc thin film before (a) and after (b) the application of an electric field with a
constant voltage of 3 V for 30 min. The figure shows that the XPS exhibits a new peak centered at 711
eV after the action of an electric field, which can be assigned to the formation of ferrocinium.1
Reference
1
S. J. Higgins, C. L. Jones and S. M. Francis, Synth. Met., 98, 211 (1999).
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