Digital logic circuit based on a single molecular system of salicylidene schiff base

Article abstract of DOI:10.1021/jp062476w

The salicylidene Schiff base N-3,5-dichloro-salicylidene-(S)-α- phenylethylamine (SPEA) has been synthesized and characterized. Stimulated by one optical input (UV light) and two chemical inputs (OH^- and Zn ²⁺), SPEA undergoes reactions of photochemistry, deprotonation, and complexation. Tailing these reactions by means of the UV-vis absorption spectra and fluorescence spectra, two obvious optical outputs, an absorption band at 323 nm and a fluorescent emission peak at 460 nm, have been obtained. On the basis of encoding binary digits in these inputs and outputs applying positive logic conventions, one monomolecular circuit, which integrates one OR, two NOT, and four AND gates, has been achieved.

Full text of DOI:10.1021/jp062476w

J. Phys. Chem. B 2006, 110, 24299-24304
24299
Digital Logic Circuit Based on a Single Molecular System of Salicylidene Schiff Base
Liyan Zhao, Dan Sui, Jia Chai, Yue Wang, and Shimei Jiang*
Key Laboratory for Supramolecular Structure and Materials of Ministry of Education, Jilin UniVersity,
2699 Qianjin Street, Changchun 130012, P. R. China
ReceiVed: April 22, 2006; In Final Form: September 28, 2006
The salicylidene Schiff base N-3,5-dichloro-salicylidene-(S)-R-phenylethylamine (SPEA) has been synthesized
and characterized. Stimulated by one optical input (UV light) and two chemical inputs (OH- and Zn2+),
SPEA undergoes reactions of photochemistry, deprotonation, and complexation. Tailing these reactions by
means of the UV-vis absorption spectra and fluorescence spectra, two obvious optical outputs, an absorption
band at 323 nm and a fluorescent emission peak at 460 nm, have been obtained. On the basis of encoding
binary digits in these inputs and outputs applying positive logic conventions, one monomolecular circuit,
which integrates one OR, two NOT, and four AND gates, has been achieved.
Introduction
complex displays strong fluorescence emission. So, it is a desired
molecule that may form the fluorescence switch. Third, it is a
In the process of miniaturization of electronic devices, organic
molecules have played an important role in transferring,
processing, and storing information in binary form.1-6 Within
the past decade, many inspirational examples of molecular logic
gates (AND,7 NOT,8 OR,9 XOR,10 NOR,11 XNOR,12 etc.) have
been reported. However, these simple logic gates must be
integrated into more complex logic circuits for further applica-
tion in future nanoprocessors and molecular computers. The
transition from simple logic gates to complex digital circuits
requires the chemical material that is able to process multiple
inputs and outputs.
photochromic molecule, which can transform from the enol form
to the keto form under UV light irradiation. With these
considerations in mind, we introduce the OH-, Zn2+, and UV
light as the inputs; consequently, two obvious optical signals
have been presented. So, a complex monomolecular logic circuit
that can transduce one optical and two chemical inputs into two
optical outputs has been demonstrated. This is the first report
that a salicylidene Schiff base can be used for this particular
kind of monomolecular logic circuit.
Experimental Section
Some multi-input and multi-output logic circuits based on a
single molecule or the combination of two molecules have been
demonstrated.13-15 Among them, the monomolecular logic
circuit is very attractive since possible mutual interferences due
to intermolecular interactions can be avoided, and thus, signal
processing and communication would become more reliable.16
Until recently, the organic materials which can be used to
simulate the multi-input and multi-output logic circuit at the
monomolecular level are rare. Only a few molecular systems
have been successfully reported, such as spiropyran13,16 and
benzylisoquinoline,14a and so forth.
In this paper, we selected the single molecular entity N-3,5-
dichloro-salicylidene-(S)-R-phenylethylamine (SPEA) to mimic
the monomolecular logic function. Concerning SPEA, the
former contributions are mainly focused on its complexes. Its
complex with lanthanum is a good catalyst for olefin epoxida-
tion,17 and its nickel complex was used to study the property
of solvatochromism.18 So far, systemic research on the property
of ligand SPEA has not been done. In fact, its novel chemical
and optical properties make it suitable to apply in a molecular
logic circuit design.
Materials. 3,5-Dichloro-salicylaldehyde and (S)-R-phenyl-
ethylamine were purchased from Aldrich. The salicylidene
compound SPEA is synthesized by the condensation of the
corresponding amines with salicylaldehyde according to the
standard procedures as previously reported.19 Pure SPEA is
obtained after recrystallization twice from absolute ethanol. The
analysis data are as follows.
SPEA: 1H NMR (500 MHz, CDCl3, 25 °C, TMS): δ ) 14.71
3
(s, 1H), 8.28 (s, 1H), 7.40-7.14 (7H; Ar-H), 4.63 (q, J (H,
3
H) ) 6.57 Hz), 1.66 (d, J (H, H) ) 6.69 Hz, 3H). FTIR
transmission (KBr pellet): 3253 cm-1 (νOH), 2981 cm-1 (νCH3),
2771 cm-1 (νOH), 1629 cm-1 (νCdN + νCdC), 1598 cm-1 (νCd
C), 1490 cm-1 (νC-O + νCdC) 1450 cm-1 (νC-N), 1376 cm-1
(δCH in CH-N), 1330 cm-1 (νCdC), 1218 cm-1 (νCO + νOH),
1178 cm-1 (νC-H in phenyl), 1126 cm-1 (νCdC), 1029 cm-1
(νCdC), 999 cm-1 (νCdC). MS: m/z ) 293 (M+). Anal. Calcd
for C15H13Cl2NO (294.18): C, 61.24; H, 4.45; N, 4.76. Found:
C, 61.64; H, 4.43; N, 4.47.
Experimental Details for Spectral Studies. All of the
spectral analyses are accomplished in spectrograde ethanol. The
concentration of SPEA solution for spectral analysis is 6.5 ×
10-5 M. Solutions for UV-vis absorption or fluorescence
spectrophotometric titration are titrated directly in 1 cm absorp-
tion cells by successive additions of corresponding chemical
reagent using a microliter syringe. After addition of each aliquot,
the cell is capped and mixed by inversion and the spectrum is
retaken. A low-pressure mercury lamp is used as the light source
for irradiation reaction.
The reason that SPEA can execute the novel logic circuit
reported in this paper comes from the following chemical and
optical properties. First, the phenolic group is quite sensitive to
base and acid, so it is a potential candidate for a fabricating pH
switch. Second, the SPEA is nonfluorescent, but its zinc
* Towhomcorrespondenceshouldbeaddressed.E-mail: smjiang@jlu.edu.cn.
Tel.: +86-431-5168474. Fax: +86-431-5193421.
10.1021/jp062476w CCC: $33.50 © 2006 American Chemical Society
Published on Web 11/09/2006

24300 J. Phys. Chem. B, Vol. 110, No. 48, 2006
Zhao et al.
Instrumentation. The UV-vis absorption spectra are taken
on a Shimadzu 3100 UV-Vis-NIR recording spectrophotom-
eter using a 3 nm slit width. The fluorescence spectra are
determined with a Shimadzu RF-5301 PC spectrofluoropho-
tometer using 3 nm input and 3 nm output width (excitation at
370 nm). 1H NMR (TMS) are recorded on a Bruker UltraShield
500 MHZ spectrometer. The FTIR transmission spectrum is
performed on a Bruker IFS66V FTIR spectrometer equipped
with a DTGS detector for KBr pellet. Sample chamber and
optics are vacuumed to eliminate carbon dioxide and water in
the air. The mass spectroscopy is measured on a Finnigam
TRACE-MG mass spectrometer. Elemental analyses were
performed by a Perkin-Elemer PE 2400 elementar.
Quantum Yield Measurement. The quantum yield is
measured at room temperature by a single excitation wavelength
(370 nm, which is coming from the Xenon lamp of the
spectrofluorophotometer) referenced to quinine sulfate in sulfuric
acid aqueous solution (φfr ) 0.546) and calculated according
to the eq 1,20 where φfs is the radiative quantum yield of the
sample; φfr is the radiative quantum yield of the standard; As
and Ar are the absorbances of the sample and standard at the
excitation wavelength, respectively; Ds and Dr are the integrated
areas of the emission for sample and standard, respectively; Ls
and Lr are the lengths of the absorption cells for the sample
and standard test; and Ns and Nr are the indexes of refraction of
the sample and standard solutions (pure solvents were assumed),
respectively.
Figure 1. (a) Absorption spectra and (b) fluorescence spectra (λex
)
370 nm) of SPEA before (dashed line) and after titration with NaOH
(solid line).
Ns2 Ds
SCHEME 1: Transitions between SPEA and SPEA-1
1 - 10-ArLr
Φfs ) Φfr ×
×
×
(1)
1 - 10-AsLs Nr2
Dr
Results and Discussion
Absorption and Fluorescence Spectral Changes Under the
Stimulations of Three Inputs.
spectrum recorded before Zn2+ addition shows that the intensi-
ties of original peaks at 425 and 335 nm decrease and an
increase takes place at the shorter 275 nm band. Four isosbestic
points are observed at λ ) 263, 290, 350, and 413 nm,
respectively. A new broad band at 386 nm due to the N,O-
complexation with Zn2+ develops.26
Plots of the decrease in absorbance at 335 nm and the increase
in absorbance at 386 nm reach the saturation point when the
ratio of Zn2+ reaches the equivalent concentration, indicating
that the Zn2+:SPEA ) 1:2 (Figure 2b). The further proof for
the ratio of 1:2 complexation can be achieved from the classical
Job plot.27 The Job plot (Figure 2c) shows a maximum value
for the absorbance at 386 nm when the molar fraction of Zn2+
reaches 0.333, which is also a signature of a 1:2 binding between
the ligand SPEA and Zn2+, as shown in Scheme 2.
Action of OH- (IN1). The phenolic group is quite sensitive
to bases and acids, thus when OH- is added into the system,
the deprotonation takes place immediately, so we selected OH-
as the first input signal. Continuous titration SPEA with NaOH
induces obvious absorption spectral changes just as those shown
in Figure 1a: the two original maximal absorptions at 425 nm
(zwitterionic form21,22) and 335 nm (CdN n-π* transition23-25
)
gradually decrease. At the same time, a new absorption at 380
nm emerges and intensifies by degrees through two isosbestic
points of λ ) 341.5 and 414.5 nm, respectively. This new
absorption is assigned to the deprotonation product SPEA-126
(Scheme 1). Strong changes are also observed in the emission
spectra (Figure 1b) where a maximum band at 469 nm (λshort
)
and a shoulder at 530 nm (λlong) arise upon addition of NaOH.
The reversibility of the deprotonation-protonation is demon-
strated by the introduction of HCl into the SPEA-1 solution.
The absorption spectra shown in Figure 1a recover completely
upon gradual addition of HCl (Figure S-4, Supporting Informa-
tion). This circle is repeated, and the absorption intensity
changes are monitored when the sample is exposed to alternating
solutions of base and acid.
The emission spectrum of SPEA is quite sensitive to the
presence of the Zn2+ ion. Figure 3a shows the fluorescence
spectra of the spectrophotometric titration of SPEA with Zn2+
.
The fluorescence intensity of SPEA in ethanol is very weak,
but a remarkable blue emission at 460 nm is observed by adding
a small amount of Zn2+ to the SPEA solution. The fluorescence
intensity of this complex gradually increases until the Zn2+
amount reaches the complexation concentration.
To further explore the luminescent property of this complex,
the fluorescence quantum yields of the SPEA system were
recorded. From the job plot in Figure 3b, we can observe that
the significant increase in fluorescence quantum yield results
from the complexation with Zn2+: from 0.0024 (for SPEA) to
0.076 (for SPEA-2). When the molar ratio of Zn2+ reaches the
complexation ratio (0.333), the quantum yield has reached the
highest value.
Action of Zn2+ (IN2). The salicylidene Schiff base can bind
with many transition metal ions. Especially zinc complexes often
display strong fluorescence emission, which can be used as a
detectable output signal for molecular devices. So, we introduced
the Zn2+ ion as the second input signal.
Complexation takes place immediately when Zn2+ is added
into the system. Titration of SPEA with Zn2+ causes obvious
changes in the absorption spectra, as shown in Figure 2a. The
spectrum obtained at the end of titration compared with the

Single Molecular System of Salicylidene Schiff Base
J. Phys. Chem. B, Vol. 110, No. 48, 2006 24301
Figure 3. (a) Fluorescence spectra (λex ) 370 nm) of ligand SPEA
(dashed line) and titration with Zn2+ (solid line): [SPEA] ) 6.5 ×
10-5 M, [Zn2+] ) 0, 0.3, 0.9, 1.5, 2.1, 2.7, 3.0, 3.3, 3.9, 4.5 × 10-5 M;
Figure 2. (a) Absorption spectral changes of SPEA ligand (dashed
line) and upon titration with Zn2+ (solid line): [SPEA] ) 6.5 × 10-5
M, [Zn2+] ) 0, 0.3, 0.9, 1.5, 2.1, 2.7, 3.0, 3.3, 3.9, 4.5 × 10-5 M; (b)
titration profiles at 335 and 386 nm; (c) Job plot of absorbance at 386
(b) Job plot of the quantum yields and the molar fraction of Zn2+
.
nm and the molar fraction of Zn2+
.
SCHEME 2: Transitions between SPEA and SPEA-2
Action of UV Light (IN3). The salicylidene Schiff base is a
well-known family of photochromism. So, we choose UV light
as the third input signal. The studies on the photochromic trait
of these Schiff base derivatives have been continued for several
decades.28 As a member of this family, SPEA can also respond
to photic and thermic stimulations and perform the reversible
reaction (Scheme 3). By irradiation with 254 nm UV light, the
electronic absorption spectra of SPEA gradually changes (Figure
4a): the original absorption bands at 425 and 335 nm decrease
along with the increase of the absorbance at 280 nm which
corresponds to the keto form.28e These results clearly indicate
that the SPEA has changed to the keto form SPEA-3 under
UV irradiation. This photochromism process is completed in
the course of 20 min under the present experimental conditions.
It should be noted that the spectral changes shown here are not
obvious enough and no clear isosbestic points are observed. This
is attributed to the influence of ethanol solvent. Ethanol is a
strong polar solvent which will affect the proton-transfer process
of photochromism. If we replace ethanol by chloroform, then
immediate and progressive spectral changes with well-defined
isosbestic points are observed (Figure S-5, Supporting Informa-
tion). But, all of the other input stimulations are acted in ethanol
solvent. To keep the stimulations being accomplished in the
same environment, here we present the photochromic results
in ethanol. The reversibility of the photochromism can be driven
by heating (Figure S-6, Supporting Information).
Figure 4. (a) Absorption spectra and (b) fluorescence spectra (λex
)
370 nm) of SPEA before (dashed line) and after continuous irradiation
by 254 nm UV light (solid line).
SCHEME 3: Transitions between SPEA and SPEA-3
Photochromism results in fluorescent enhancements (Figure
4b). Just as reported by Barbara et al., the fluorescent emission
of the salicylidene Schiff base in the enol form is very low but
in the keto form the emission is stronger.29

24302 J. Phys. Chem. B, Vol. 110, No. 48, 2006
Zhao et al.
Figure 6. (a) Absorption spectra of SPEA-1 (dashed line) and after
continuous irradiation by 254 nm UV light (solid line); (b) fluorescence
spectra (λex ) 370 nm) of SPEA solution (dashed line) and after
irradiation of the SPEA-1 by 254 nm UV light (solid line).
Figure 5. (a) Absorption spectra and (b) fluorescence spectra (λex
370 nm) of the deprotonation (step 1, dashed line) and the following
complexation reactions (step 2, solid line).
)
Actions of OH- and Zn2+ (IN1 and IN2). Now let us turn
our attention to the coordinated actions of two inputs. First, by
titrating SPEA with NaOH, as shown in Figure 5a (step 1), the
typical absorption band at 380 nm emerges. This result exhibits
that the ligand SPEA is deprotonated and transformed to SPEA-
1. Then by titrating SPEA-1 with Zn2+, the absorption band at
380 nm decreases and is red-shifted to 386 nm (Figure 5a, step
2). As mentioned above, the band at 386 nm results from the
zinc complex SPEA-2. So after this two-step process, we also
obtain the complex SPEA-2.
This two-step process is further verified by fluorescent
spectroscopy. As shown in Figure 5b, SPEA is nonfluorescent.
After deprotonation, the SPEA-1 gives a weak emission band
at 469 nm. However, a significant fluorescence enhancement
is produced by titrating SPEA-1 with Zn2+ where a band arises
at 460 nm. The intensity of such a band increases upon addition
of Zn2+. Finally, the intensity reaches the equivalent value
shown in Figure 3a under the same excitation wavelength of
370 nm. The fluorescent spectroscopic investigation is consistent
with the UV-vis spectra as mentioned above.
Figure 7. Fluorescence spectra of SPEA-2 (dashed line) and after
continuous irradiation by 254 nm UV light (solid line). Inset shows
emission photographs in the ethanol solution: (1) the ligand SPEA in
the absence of Zn2+, (2) the Zn2+ complex SPEA-2, and (3) the SPEA-2
after irradiated by 254 nm UV light.
nated product.30 From the corresponding fluorescence spectra
(Figure 6b), we can see SPEA is nearly nonemissive (dashed
line), but the new photoproduct displays a strong emission at
494 nm (solid line). The possible molecular structure of this
new photoproduct has been presented in the Supporting
Information.
Actions of OH- and UV Light (IN1 and IN3). First, by
titrating SPEA with NaOH, we get SPEA-1. Then, exposure
of SPEA-1 to UV light at 254 nm leads to an unexpected
absorption phenomenon, which is shown in Figure 6a. It is found
that the initial absorbance at 380 nm (due to SPEA-1) reduces
gradually along with a new absorption band centered at 323
nm which appears and increases. The absorbance between 355
and 420 nm decreases during irradiation, while the absorbance
between 300 and 355 nm increases. A clear isosbestic point is
found at 355 nm indicating that only two species are involved
in the process. After the UV light irradiation for 20 min, the
spectra will not change anymore. The new absorption band at
323 nm is blue-shifted as much as 57 nm (∆λmax ) 380-323
nm) compared with the one at 380 nm. Such a large blue shift
may be aroused from the ring-closed reaction of the deproto-
Actions of Zn2+ and UV Light (IN2 and IN3). As
mentioned above, when SPEA is titrated with Zn2+, the complex
SPEA-2 is formed. Then we utilize the UV light to stimulate
this complex. As shown in Figure 7, the intensity of the
fluorescence at 460 nm (the emission of SPEA-2) fades
gradually with irradiation by 254 nm UV light. Finally, the
bright luminescence disappears when the irradiation time reaches
25 min. This result indicates that the complexation reaction can
be reversed back under the UV light irradiation (Scheme 2).
Additionally, this bright emission can be obtained again after
it was maintained in the dark. The appearance and disappearance

Single Molecular System of Salicylidene Schiff Base
J. Phys. Chem. B, Vol. 110, No. 48, 2006 24303
Figure 9. Under the stimulation of OH- (IN1), Zn2+ (IN2), and UV
light (254 nm, IN3) (IN1, IN2, IN3 in the string of a: 0 0 0; b: 0 0 1;
c: 0 1 0; d: 0 1 1; e: 1 0 0; f: 1 0 1; g: 1 1 0; h: 1 1 1), (a) the
fluorescence spectra (λex ) 370 nm) and (b) the changes of fluorescence
intensity at 460 nm (0 represents inputs that are 0, 9 represents inputs
that are 1).
Figure 8. Under the stimulation of OH- (IN1), Zn2+ (IN2), and UV
light (254 nm, IN3) (IN1, IN2, IN3 in the string of a: 0 0 0; b: 0 0 1;
c: 0 1 0; d: 0 1 1; e: 1 0 0; f: 1 0 1; g: 1 1 0; h: 1 1 1), (a) the
absorption spectra and (b) the changes of absorbance at 323 nm (0
represents inputs that are 0, 9 represents inputs that are 1).
TABLE 1: Truth Table for the Monomolecular Circuit
of this characteristic fluorescence emission (at 460 nm) is
convictive proof not only for its complexation reversibility but
also for its switching ability as a fluorescence switch.
Input
Output
IN1
IN2
IN3
hν
OUT1 absorption
OUT2 emission
at 460 nm
Actions of OH-, Zn2+, and UV Light (IN1, IN2, and IN3).
Finally, we introduce all of these three inputs to SPEA one by
one. As discussed above, by titrating SPEA with NaOH, we
OH-
Zn2+
at 323 nm
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
0
0
0
0
1
0
0
0
0
1
0
0
0
1
0
get deprotonated SPEA-1. Then, by titrating SPEA-1 with Zn2+
,
we get the SPEA-2 complex. Next, by irradiating SPEA-1 with
254 nm UV light, we get SPEA again.
In summary, under the individual actions of the OH- ion,
Zn2+ ion, and UV light as well as the combination of these,
SPEA can accomplish the reactions of deprotonation, complex-
ation, and photochemistry producing two obvious optical
outputs: a UV-vis absorption band at 323 nm and a fluorescent
emission peak at 460 nm.
) 0, and IN3 ) 1 does the output signal OUT1 ) 1. Otherwise,
OUT1 ) 0. The absorption spectral changes and logic properties
of above reactions are shown in parts a and b of Figure 8, which
demonstrate also that only when the three inputs are in the string
of 1 0 1 is OUT1 higher than the threshold value (0.20).
From the spectral investigations illustrated above, the fluo-
rescent emission band at 460 nm (OUT2) can be achieved in
Binary Logic Analysis for the Multi-input and Multi-
output Molecular Logic Circuit. The communication between
the input signals, OH- (IN1), Zn2+ (IN2), and UV light (254
nm, IN3) and output signals, an absorption band at 323 nm
(OUT1) and a fluorescent emission band at 460 nm (OUT2),
can be described with binary logic.31 These inputs and outputs
can be encoded with binary digits applying positive logic
conventions (off ) 0, on ) 1). If we regard absorbance of 0.20
and a fluorescence intensity of 300 as the threshold values,
OUT1 ) 0 and OUT 2 ) 0 when their corresponding spectral
values are lower than 0.20 and 300; OUT 1 ) 1 and OUT 2 )
1 when their corresponding spectral values are higher than 0.20
and 300. Just as the spectroscopic analyses, three input
stimulations will control the intensity of two output signals.
As discussed above, the absorbance at 323 nm (OUT1) is
high enough only under the simultaneous actions of OH- (IN1)
and 254 nm UV light (IN3), namely, only when IN1 ) 1, IN2
two situations: one is by directly titrating SPEA with Zn2+
,
the other one is by titrating the deprotonated form SPEA-1 with
Zn2+. In other words, only when IN1 ) 0, IN2 ) 1, and IN3 )
0 or IN1 ) 1, IN2 ) 1, and IN3 ) 0 can OUT2 ) 1. The
fluorescent spectral changes and logic properties of above
reactions are shown in parts a and b of Figure 9 which reveal
also that, when the three inputs are in the string of 0 1 0 or 1
1 0, the fluorescent intensity at 460 nm (OUT2) is higher than
the threshold value (300).
According to the two histograms (Figure 8b and Figure 9b),
the truth table (Table 1) can be achieved. From which, we can
see that this chemical system responds to an input string of three
binary digits (IN1, IN2, IN3) producing an output string of two

24304 J. Phys. Chem. B, Vol. 110, No. 48, 2006
Zhao et al.
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Figure 10. Combinational logic circuit equivalent to the SPEA
molecular system.
binary digits (OUT1, OUT2). For example, the input string 0 0
0 indicates that all three input stimulations are off. Under this
condition, the absorbance at 323 nm (OUT1) and the fluorescent
intensity at 460 nm (OUT2) are lower than their threshold values
(0.20 and 300). The output string is 0 0. Instead, an input string
of 1 1 0 indicates that the IN1 (OH-) and IN2 (Zn2+) are on
but the IN3 (UV light of 254 nm) is off. Under this condition,
the fluorescent intensity at 460 nm is high, while the absorbance
at 323 nm is low. The output string is 0 1. Following similar
considerations, the eight output strings corresponding to the eight
possible combinations of input strings can be determined.
Consequently, the absorbance changes at 323 nm and the
fluorescent intensity changes at 460 nm upon the external inputs
of OH- (IN1), Zn2+ (IN2), and UV light (254 nm, IN3) can be
interpreted as a monomolecular circuit, which integrates one
OR, two NOT, and four AND gates, as shown in Figure 10.
One portion of the logic circuit combines the three inputs
through one NOT and two AND operations producing the output
OUT1. The other combines the three inputs through one NOT,
one OR, and two AND operations resulting in the output OUT2.
From Figure 10, we may note that the IN2 must be off when
the OUT1 is on and the IN3 must be off when the OUT2 is on.
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Conclusions
The salicylidene Schiff base SPEA is synthesized and
characterized. Under the individual actions of the OH- ion, Zn2+
ion, and UV light as well as the combination of these actions,
we successfully obtained a multi-input and multi-output mono-
molecular circuit, which responds to one optical and two
chemical inputs producing two optical outputs. This contribution
not only develops a complex logic function based on one simple
molecule by elaborate chemical design but also presents a
possible material for future molecular data-processing, -storage,
and -communication devices.
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Acknowledgment. This work was supported by the National
Natural Science Foundation of China (50573029, 50225313, and
50520130316) and the 111 Project (B06009) and Program for
Changjiang Scholars and Innovative Research Team in Uni-
versity (PCSIRT0422).
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Supporting Information Available: The 1H NMR and
FTIR spectra of SPEA, the stability and the further structural
information about the new photoproduct, the UV-vis absorption
spectra of the reversible processes of deprotonation and pho-
tochromism, and the UV-vis absorption spectra of SPEA
photochromism in chloroform are given. This material is
available free of charge via the Internet at http://pubs.acs.org.
References and Notes
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