The sequential absorption technique is illustrated in the
ESI.z This sequential absorption technique allows for the
fabrication of PBA thin films, with large surface coverage
and tunable thickness and composition, onto a wide variety of
substrates.
boundary in the Prussian blue analogue thin films, preventing
PBA deposition with a clear acrylic, to investigate the difference
in height between the solid support and the surface of the film.
The root mean square (rms) roughness of the films is defined as
the average of height deviations taken from the mean thickness
plane. Melinex supports, used for sequential absorption of 200
cycle thin films, were cut into squares with sizes of 1 cm2 and
coated with a thin film of carbon for SEM and EDS measure-
ments. For SQUID measurements, the thin films were cut into
B10.5 mm2 squares and stacked, with surfaces parallel, into a
polyethylene sample holder. Background contributions of the
solid support and sample holder were removed by subtracting
their previously measured susceptibilities from the raw magnetic
data of the thin films.
A Melinex solid support is immersed 5 times in a 10 mM
M1(NO3)2ꢀ6H2O(aq) (M1 = Co, Ni, Cu, or Zn) aqueous
solution containing divalent transition metal ions and rinsed
twice with DI water. Next, the Melinex substrate is dipped
5
times in an aqueous solution containing 12.5 mM
RbNO3(aq) and K3[M2(CN)6](aq) (M2 = Cr at 10 mM or
M2 = Fe at 20 mM) and then rinsed with DI water. For each
combination of M1 and M2, this process was repeated for
5, 10, 20, 30, 60, and 200 cycles in order to generate films of
different thickness, after which, the resulting film is rinsed with
DI water and methanol and dried under a stream of nitrogen.
A modified synthesis using spin-casting was also performed.
A solution of 10 mM K3[M2(CN)6](aq) and 12.5 mM
RbNO3(aq) was treated with 10 mM M1(NO3)2ꢀ6H2O(aq)
precipitating a microcrystalline powder product. The solid
precipitate was isolated by centrifugation, was rinsed three
times with DI water, and once with methanol. The isolated
precipitate was then dried under a stream of nitrogen, yielding
a light blue powder. The PBA precipitate was then dispersed in
ether at a concentration of 2.5 mg mLꢃ1. This solution was
then added drop wise onto a spinning Melinex solid support in
order to deposit the film.
Acknowledgements
This work was supported, in part, by NSF DMR-0701400
(MWM), NSF DMR-1005581 (DRT), and the NHMFL via
cooperative agreement NSF DMR-0654118 and the State of
Florida. We thank Ben Pletcher and the Major Analytical
Instrumentation Center (MAIC), Department of Materials
Science and Engineering, University of Florida, for the SEM
images and the EDS data.
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Fourier transform infrared (FTIR) spectra of the Prussian blue
analogue films were recorded using a Thermo Scientific Nicolet
6700 spectrometer. Tapping mode atomic force microscopy
(AFM) experiments were performed on nitrogen-dried samples
using a Multimode AFM with a Nanoscope IIIa controller
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c
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New J. Chem., 2011, 35, 1320–1326 1325