Syntheses, spectral, electrochemical and thermal studies of mononuclear manganese(III) complexes with ligands derived from 1,2-propanediamine and 2-hydroxy-3 or 5-methoxybenzaldehyde: Self-assembled monolayer formation on nanostructure zinc oxide thin fil

Article abstract of DOI:10.1016/j.saa.2011.03.055

Mononuclear Mn(III) complexes have been prepared via the Mn(II) reaction of an equimolar of Schiff-bases derived from reaction of 2-hydroxy-3- methoxybenzaldehyde or 2-hydroxy-5-methoxybenzaldehyde with 1,2-diaminopropane. Axial ligands L include: pyridin

Full text of DOI:10.1016/j.saa.2011.03.055

Spectrochimica Acta Part A 79 (2011) 666–671
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Syntheses, spectral, electrochemical and thermal studies of mononuclear
manganese(III) complexes with ligands derived from 1,2-propanediamine and
2
-hydroxy-3 or 5-methoxybenzaldehyde: Self-assembled monolayer formation
on nanostructure zinc oxide thin film
a,∗
a
b
b
Mohammad Hossein Habibi , Elham Askari , Mehdi Amirnasr , Ahmad Amiri ,
c
c
Yuki Yamane , Takayoshi Suzuki
Department of Chemistry, University of Isfahan, Isfahan, 81746-73441 I.R. Iran
Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111, Iran
Department of Chemistry, Faculty of Science, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan
a
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Mononuclear Mn(III) complexes have been prepared via the Mn(II) reaction of an equimolar
of Schiff-bases derived from reaction of 2-hydroxy-3-methoxybenzaldehyde or 2-hydroxy-5-
methoxybenzaldehyde with 1,2-diaminopropane. Axial ligands L include: pyridine (py) and H2O. The
resulting complexes have been characterized by FT-IR and UV–vis spectroscopy. The crystal structures
of the complexes were determined and indicate that in the solid state the complex adopts a slightly
distorted octahedral environment of the imine N and hydroxo O with the two axial ligands. The electro-
chemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that
the first reduction process corresponding to Mn –Mn is electrochemically quasi-reversible. Thermal
stability of these complexes was determined by TG and DTG. Layers of these complexes were formed on
nanostructure zinc oxide thin film and a red shift was observed when zinc oxide thin film is modified by
complex.
Received 1 February 2011
Received in revised form 1 March 2011
Accepted 27 March 2011
Keywords:
Mononuclear complexes
Manganese(III)
UV–vis spectroscopy
Thermal study
Electrochemical study
Crystal structure
N2O2 donors
III
II
© 2011 Elsevier B.V. All rights reserved.
1
. Introduction
Metal-chelate complexes generally offer many attractive prop-
[21–24]. Exchange between two or more paramagnetic centers
is the crucial criteria in manifestation of molecular magnetism.
Tetradentate salen type Schiff-base ligands occupy four equatorial
coordination sites of the six-coordinate metal cation, leaving axial
positions to be occupied by either terminal ligands or bridging lig-
ands that can link adjacent paramagnetic metal centers to form
dinuclear structures. Structures and magnetic properties of man-
ganese(III) salen type Schiff-base complexes have been studied,
erties, such as catalysis to development of electrochemical sensors,
single-molecule magnets and displaying a double role of elec-
tron transport and light emission [1–7]. Manganese complexes
are attracting not only in the fields of bioinorganic chemistry but
also for their ability to function as progenitors of novel mag-
netic molecular materials [8,9]. These complexes are significant
for their redox active role in some biochemical processes, and
current interests in the chemistry of higher oxidation-state man-
ganese compounds draw from their utility as models for the
photosynthetic water oxidation centers [10,11]. The role played
by manganese in a number of biological systems has driven
by the research efforts of many scientists from a variety of
fields [12–20]. Manganese(III) Schiff-base complexes also pro-
vide a rich series of structural types that can be used as models
for the magnetic and structural properties of mangano enzymes
III
ꢀ
but reports on Mn (MeOsalpn) complexes (MeOsalpn = N,N -bis(2-
ꢀ
hydroxy-3-methoxybenzylidene)propane-1,2-diamine) or N,N -
bis(2-hydroxy-5-methoxybenzylidene)propane-1,2-diamine] are
III
rare. Most reported Mn complexes are mononuclear with various
apical ligands [25–31]. There are only a limited number of dinuclear
and 1D chain structures [32–34]. Differential thermal gravimetry
(DTG) and thermogravimetry (TG) are useful to study the modes
of thermal decompositions as well as the composition of some
metal complexes of Schiff bases [35]. Several researches have pro-
posed that the redox potential in Schiff-base complexes is directly
related to chemical characteristics of the entire complex. Thus,
there has been a strong interest in determining thermodynamically
meaningful redox potentials of manganese Schiff-base complexes
and in understanding the relationship between these potentials
∗ Corresponding author. Tel.: +98 311 7932707; fax: +98 311 6689732.
E-mail addresses: habibi@chem.ui.ac.ir, habibi284@gmail.com (M.H. Habibi).
1
386-1425/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2011.03.055

M.H. Habibi et al. / Spectrochimica Acta Part A 79 (2011) 666–671
667
and the detailed structure of the Schiff-base ligand [36–38]. Over
the last decade, we have focused part of our research program
on nanostructure thin film transition metal compounds [39–42],
which constitute one of the more versatile systems in order to
mimic biological and industrial catalyses. In the present paper, we
report the synthesis, crystal structures, thermal and electrochem-
(1:2 mol stoichiometric ratio) in MeOH at room temperature and
◦
was recrystallized from methanl. Yield: 73%, mp:135 C, IR (KBr
−
1
cm ): 1627 ꢁ(C N). UV–vis (CHCl : ꢀmax, nm): 260, 335.
3
ꢀ
2.2.3. [N,N -Bis(2-hydroxy-3-methoxybenzylidene)-propane-1,2-
diamine] diaqua manganese (III) perchlorate, [Mn(2h3 mb) pn
2
III
ical studies of two mononuclear Mn (MeOsalpn)-type complexes
(H O) ][ClO ] (1)
2
2
4
with different axial ligands and immobilization on zinc oxide thin
film. The deposition of transition metal complex on the surface of
ZnO nanoparticles can enhance the photoactivation of ZnO catalyst.
Our recent study demonstrated unique reactivity of cobalt-salen
complexes codeposited onto a self-assembled monolayer surface
of ZnO using spin-coating [43]. In the present paper, we report the
synthesis, crystal structures, thermal and electrochemical studies
of two mononuclear MnIII(MeOsalpn)-type complexes with dif-
ferent axial ligands and immobilization on zinc oxide thin film.
ZnO sol was first prepared and then the influence of manganese
salen complex immobilization on surface of nanostructure ZnO was
investigated via UV–vis spectroscopy (UV–vis), cyclic voltametry
To
a
stirring solution of Mn(CH COO)2 2H O (0.0662 g,
3
2
0.500 mmol) in ethanol (25 mL) was added an equimo-
lar of N,N -Bis(2-hydroxy-3-methoxybenzylidene)-propane-1,2-
diamine (0.5 mmol) and the mixture was stirred for 2 h (Scheme 1).
The pink solution turned dark brown immediately upon the for-
ꢀ
III
mation of Mn complex and then 0.5 mmol of NaClO ·H O was
4
2
added. A dark brown microcrystalline solid was produced by slow
evaporation of ethanol at room temperature. The product was then
recrystallized from methanol–propanol (2:1, v/v) and dark brown
crystals suitable for X-ray crystallography were obtained. Yield:
◦
−1
−
89%, m.p = 256 C. ꢂ = 4.8 BM, IR (KBr cm ): 1080 (ClO4 ), 1607
(C N), 2850 (C–H sp ). UV–vis (CHCl : ꢀmax, nm): 232, 302, 350.
eff
3
3
(
CV) pattern and scanning electron microscopy (SEM) analysis. The
ꢀ
effect of modified ZnO on the separation efficiency of photogener-
ated carriers by the use of linear sweep voltametry (LSV) plots and
photoactivity of the coating is under investigation.
2.2.4. [N,N -bis(2-hydroxy-5-methoxybenzylidene)-propane-1,2-
diamine](aqua)(pyridine) manganese(III) hexafluorophosphate,
[Mn(2h5 mb) pn)(H O)(Py)][PF ] (2)
2
2
6
To
a
stirring solution of Mn(CH COO) ·2H O (0.0662 g,
3
2
2
ꢀ
2
. Experimental
0.500 mmol) in ethanol (25 mL) was added an equimolar of N,N -
bis(2-hydroxy-5-methoxybenzylidene)-propane-1,2-diamine
(0.500 mmol) and the reaction mixture was stirred for 2 h. To
this solution was added 2 mmol of pyridine in 5 mL ethanol with
stirring for 3 h and then NH4PF6 (0.5 mmol); the resulting dark
brown solution was then stirred for 5 min. A dark brown micro-
crystalline solid was produced by slow evaporation of ethanol
at room temperature. The product was then recrystallized from
methanol–propanol (2:1, v/v) and dark brown crystals suitable
2.1. Materials and methods
All solvents and chemicals were used as received, except for
the amines which were distilled under reduced pressure prior to
use. UV–vis spectra were recorded on a Varian Cary 500 Scan spec-
trophotometer. Infrared spectra (KBr pellets) were obtained on
a Bruker FT-IR (Tensor 27) spectrophotometer. Cyclic voltammo-
grams (CV) were recorded by using a SAMA Research Analyzer
M-500. Three electrodes were utilized in this system, a glassy car-
bon working electrode, a platinum disk auxiliary electrode and
◦
for X-ray crystallography were obtained. Yield: 83%, m.p = 256 C.
−
1
−
ꢂeff = 5.1 BM, IR (KBr cm ): 840 (PF6 ), 1605 (C N), 2900 (C–H
3
sp ). UV–vis (CHCl3, ꢀmax, nm): 239, 366, 365.
+
Ag/Ag as reference electrode. The glassy carbon working electrode
(
Metrohm 6.1204.110) with 2.0 ± 0.1 mm diameter was manually
2.2.5. X-ray crystallography for 1
cleaned with 1 lm alumina polish prior to each scan. Tetrabuty-
lammonium tetrafluoroborate (n-Bu) BF , was used as supporting
electrolyte. Acetonitrile was dried over CaH . The solutions were
deoxygenated by purging with Ar for 5 min. All electrochemical
potentials were calibrated versus internal Fc
SCE) couple under the same conditions. Thermal gravimetric differ-
ential thermal analysis (TG-DTA) measurements were carried using
a Mettler TA4000 system (http://ir.mt.com). Philips XL-30 scanning
electron microscopy (SEM) (www.itg.uiuc.edu) was used to image
the size and morphology of the nanoparticles.
Dark brown crystal of complex 1 was mounted with a cryoloop
and flash-cooled by cold nitrogen stream. All measurements were
made at 193(2) K on a Rigaku RAXIS RAPID imaging plate area detec-
tor with graphite monochromated Mo–K␣ radiation. Absorption
corrections were applied by the numerical method [44]. Crys-
tal data, together with other relevant information on structure
determination, are listed in Table 1. The structure was solved by
the direct method using SIR2004 [45] and refined on F2 with all
independent reflections by full-matrix least-square method using
SHELXL97 program [46]. The non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were introduced at the positions
calculated theoretically and treated with riding models.
4
4
2
+/o
(E = 0.40 V versus
0
2
.2. Synthesis
ꢀ
2
.2.1. N,N -Bis(2-hydroxy-3-methoxybenzylidene)-propane-1,2-
2.2.6. Electrochemical studies
◦
diamine
H (2h3 mb) pn N,N -Bis(2-hydroxy-3-methoxybenzylidene)-
propane-1,2-diamine was prepared by the condensation of
,2-propanediamine with 2-hydroxy-4-methoxybenzaldehyde
1:2 mol stoichiometric ratio) in methanol at room temperature
and was recrystallized from hot methanol. Yield: 84%, IR (KBr
The cyclic voltammograms of 1 and 2 were conducted at 25 C
ꢀ
under an argon atmosphere using acetonitrile solutions containing
2
2
−
3
0.05 mol dm (n-Bu)4BF4 as supporting electrolyte and complex
−
3
−3
1
(
concentrations of about 3 × 10 mol dm . The ligands are electro-
inactive over a range of +0.7 to −2.0 V.
−
1
3
cm ): 1620 (C N), 2850 (C–H sp ), 1100 and 1240 (C–O). UV–vis
CHCl : ꢀmax, nm): 245, 350.
2.2.7. Preparation of nanocrystalline zinc oxide thin films and
surface functionalization of manganese complexes
(
3
Bare zinc oxide films were deposited on a glass substrate using
our procedure reported earlier [46]. The dried films were then
preheated to 270 C over 60 min and post heated at 500 C for an
additional 30 min to remove the organic binders used in the paste
and to sinter the particles into a nanocrystalline thin film. The films
were then dyed by soaking them overnight in 2 mM solutions of the
ꢀ
2
.2.2. N,N -Bis(2-hydroxy-5-methoxybenzylidene)-propane-1,2-
◦
◦
diamine
H (2h5 mb) pn N,N -Bis(2-hydroxy-5-methoxybenzylidene)-
propane-1,2-diamine was prepared by the condensation of
,2-propanediamine with 2-hydroxy-5-methoxybenzaldehyde
ꢀ
2
2
1

6
68
M.H. Habibi et al. / Spectrochimica Acta Part A 79 (2011) 666–671
ꢀ
Scheme 1. Synthesis of [N,N -bis(2-hydroxy-3-methoxybenzylidene)-propane-1,2-diamine] diaqua manganese(III) perchlorate complex, [Mn(2h3 mb)2pn)(H2O)2][ClO4]
1).
(
manganese complexe 2 in anhydrous acetonitrile. The films were
immersed and rinsed with fresh acetonitrile to remove unadsorbed
dye.
3
. Results and discussion
Two MnIII complexes have been prepared by the reaction
ꢀ
of an equimolar of N,N -Bis(2-hydroxy-3-methoxybenzylidene)-
ꢀ
propane-1,2-diamine or N,N -Bis(2-hydroxy-5-methoxybenzyl-
idene)-propane-1,2-diamine and manganese(II) acetate in the
presence of the appropriate axial ligands (water or pyridine) in aer-
obic conditions (Scheme 1). The air oxidation was continued for a
period of 2 h, which the dark brown color solution resulted. Dark
brown crystals of these complexes were obtained in good yield
(
83–89%). TG-DTA analysis was conducted to clarify the thermal
stability of the two complexes before self assembely on nanostruc-
ture ZnO thin films. TG-DTA of 1 and 2 are shown in Figs. 1 and 2
respectively. TG-DTA results indicate that complexes 1 and 2 show
◦
major weight lose at 297 and 200 C respectively. In the unsym-
ꢀ
[N,N -bis(2-hydroxy-3-methoxybenzylidene)-
Fig.
1. TG-DTG
curve
of
propane-1,2-diamine] diaqua manganese(III) perchlorate complex, [Mn(2h3
mb)2pn)(H2O)2][ClO4] (1).
Table 1
Crystal data and structure refinement for [Mn(2h3 mb)2pn)(H2O)2][ClO4], (1).
Identification code
mhhasg152
metric unit of 1, there is a crystallographically independent Mn
Chemical formula (moiety)
Chemical formula (total)
Formula weight
MnC19H24N2O10Cl
MnC19H24N2O10Cl
516.5
200(2) K
MoK␣, 0.71075 A˚
Monoclinic, P21/n
a = 13.218(3) A˚ ˛ = 90
b = 13.179(3) A˚ ˇ = 117.985(5)
c = 14.249(2) A˚ ꢃ = 90
2191.9(7) A˚ 3
plane with a slightly distorted octahedral environment (Fig. 3). The
III
equatorial plane of Mn has two nitrogen and two oxygen atoms
of the N O2 ligand with the bond distances of Mn1–O1 1.861(2),
2
Temperature
Mn1–O2 1.861(2), Mn1–N1 1.964(2), Mn1–N2 1.964(2) A˚ . The two
Radiation, wavelength
Crystal system, space group
Unit cell parameters
axial positions are occupied by two oxygen atoms from water with
the bond distances of Mn1–O5 2.224(2), Mn1–O6 2.341(2) A˚ . These
◦
◦
◦
Cell volume
Z
4
3
Calculated density
Absorption coefficient ␮
F(000)
1.608 g/cm
0.078 mm
1096
−1
3
Crystal colour and size
Reflections for cell refinement
Data collection method
Dark red, 0.15 × 0.15 × 0.15 mm
◦
28 (ꢄ range 3.09–27.48 )
Rigaku RAXIS-RAPID diffractometer
Scans
3.09–27.48.0
␻
◦
ꢄ range for data collection
Index ranges
Completeness to ꢄ = 24.0
h −17 to 16, k −17 to 17, l −18 to 17
◦
99.4%
Reflections collected
4940
Independent reflections
Reflections with F2 > 2␴
Absorption correction
Min. and max. transmission
Structure solution
2854 (Rint = 0.042)
2015
Multi-scan Higashi.t(1995)
0.892 and 0.892
Direct methods
2
Refinement method
Full-matrix least-squares on F
Weighting parameters a, b
Data/restraints/parameters
Final R indices [F2 > 2␴]
R indices (all data)
0.0611, 1.1171
2854/2/237
R1 = 0.0659, wR2 = 0.1450
R1 = 0.1043, wR2 = 0.1605
1.167
Goodness-of-fit on F2
Extinction coefficient
Largest and mean shift/su
Largest diff. peak and hole
0.012(2)
ꢀ
Fig. 2. TG-DTG curve of [N,N -bis(2-hydroxy-5-methoxybenzylidene)-propane-
0.000 and 0.000
0.34 and − 0.24 e A˚ −
1,2-diamine] aqua pyridine manganese(III) hexafluorophosphate complex (2),
3
[
Mn(2h5 mb)2pn)(H2O)(Py)][PF6].

M.H. Habibi et al. / Spectrochimica Acta Part A 79 (2011) 666–671
669
ꢀ
Fig. 3. ORTEP drawing of [N,N -bis(2-hydroxy-3-methoxybenzylidene)-propane-
,2-diamine] diaquo manganese(III) perchlorate complex (1) with the atom
1
numbering scheme. The displacement ellipsoids are drawn at the 50% probability
level.
Mn–O distances are significantly longer than those of Mn1–O1 and
ꢀ
Mn1–O2 in the equatorial planes, consistent with the John–Teller
Fig. 5. UV–vis spectra of [N,N -bis(2-hydroxy-3-methoxybenzylidene)-propane-
1,2-diamine] diaqua manganese(III) perchlorate] in ethanol (a) and [N,Nꢀ-
elongation of high spin d4 MnIII in the axial direction and the dif-
bis(2-hydroxy-5-methoxybenzylidene)-propane-1,2-diamine] aqua pyridine man-
ganese(III) hexafluorophosphate in ethanol (b).
ference in ligand type.
3
.1. Voltammetric characterization
first, the decrease of the peak currents and second the shifts of
potential values as the treatment time presumably due to the
concomitant substitution of the axial ligands by acetonitrile in a
solvolysis reaction [48–50,29]. FT-IR spectral data of the complexes
The cyclic voltammograms of complexes 1 and 2 were measured
in acetonitrile solution (Fig. 4). The two cyclic voltammograms have
almost the same shape, and both exhibit only one quasi-reversible
redox couple. These results demonstrate that both complexes
present only a single species in acetonitrile solution. The redox pro-
cesses may be described as Mn /Mn and Mn /Mn . This character
can also be seen in the analogous [Mn (salen)(dca)] complex [47].
ꢀ
were compared with those of the uncomplexed ligand. Both N,N -
bis(2-hydroxy-3-methoxybenzylidene)propane-1,2-diamine and
ꢀ
III
II
II
III
N,N -bis(2-hydroxy-5-methoxybenzylidene)propane-1,2-diamine
III
ligand show a broad band characteristic of the OH group in the
−
1
3
300–3500 cm
region. The disappearance of this band in the
FT-IR spectra of the complexes is indicative of the fact that the
3
.2. Spectroscopic properties
tetradentate N O2 ligands are coordinated as dianions. The (C N)
2
−
1
band appearing at 1620 cm
in the ligands is shifted to lower
The electronic spectra of complexes 1 and 2 in methanol have
−
1
frequencies by 13–25 cm in the corresponding Mn complexes,
indicating that the ligands are coordinated to the metal ions
through the imino groups (Supplementary Information). The
morphology and particle size of pure zinc oxide thin film and zinc
oxide thin film modified by [Mn(h5 b pn)(H O)(Py)][PF ] complex
two maxima at 232 and 302 nm for 1 and 238 and 360 nm for
, respectively, which essentially show the absorption of the
2
Schiff-base ligand (Fig. 5). The absorptions at 232 and 238 nm
can be related to the spin allowed ꢅ–ꢅ* azomethane intraligand
transition [26]. The band at 360 nm in the UV region can be
assigned to spin-allowed metal-to-ligand charge transfer (MLCT)
transition. During the experiment two phenomena were observed;
2
2
6
are investigated by SEM shown in Figs. 6 and 7 respectively. The
average grain size of pure ZnO thin films was near 40 nm with
granular shape and compact regular morphology (Fig. 6). On the
ꢀ
Fig. 4. Cyclic voltammogram corresponding to Mn(III) → Mn(II) of [N,N -bis(2-
hydroxy-3-methoxybenzylidene)-propane-1,2-diamine] diaqua manganese(III)
perchlorate complex, [Mn(2h3 mb)2pn)(H2O)2][ClO4], (dot line) (1) Mn(2h5
mb)2pn)(Py)(H2O)][PF6], (solid lines) (2) in acetonitrile solution stored for 48 h at
93 K. Scan rate: 100 mV/s. c = 3.0 × 10−3
Fig. 6. SEM image of the pure zinc oxide thin film.
2
.

6
70
M.H. Habibi et al. / Spectrochimica Acta Part A 79 (2011) 666–671
plexes present only a single species in acetonitrile solution and the
III
II
II
III
redox processes may be described as Mn /Mn and Mn /Mn . TG-
DTA results indicate that complexes 1 and 2 show major weight lose
◦
at 297 and 200 C respectively. The average grain size of pure ZnO
thin films was near 40 nm with granular shape and compact regu-
lar morphology. The zinc oxide thin film nanoparticles modified by
[
Mn(h5 mb pn)(H O)(Py)][PF ] complex had a nanometer size and
2 2 6
aggregated morphologies
4.1. Electronic supplementary material
CCDC 806181 contains the supplementary crystallographic data
for 1. These data can be obtained free of charge via http://www.
ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK,
fax: (+44) 1223-336-033, or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgements
The authors wish to thank the University of Isfahan for finan-
cially supporting this work.
Fig. 7. SEM image of the zinc oxide thin film modified by complex 2.
References
[
[
[
[
[
1] C.W. Tang, S.A. Van Slyke, Appl. Phys. Lett. 51 (1987) 913.
2] C.W. Tang, S.A. Van Slyke, C.H. Chen, J. Appl. Phys. 65 (1989) 3610.
3] L. Canali, D.C. Sherrington, Chem. Soc. Rev. 28 (1999) 85.
4] F. Fache, E. Schulz, M.L. Tommasino, M. Lemaire, Chem. Rev. 100 (2000) 2159.
5] N.S. Venkataramanan, G. Kuppuraj, S. Rajagopal, Coord. Chem. Rev. 249 (2005)
1249.
[
[
[
[
6] O. Fatibello-Filho, E.R. Dockal, L.H. Marcolino-Junior, Anal. Lett. 40 (2007) 1825.
7] H. Miyasaka, A. Saitoh, S. Abe, Coord Chem. Rev. 251 (2007) 2622.
8] R. Sessoli, D. Gatteschi, A. Caneschi, M.A. Novak, Nature 365 (1993) 141.
9] R. Sessoli, H.L. Tsai, A.R. Schake, S.Y. Wang, J.B. Vincent, K. Folting, D. Gatteschi,
G. Christou, D.N. Hendrickson, J. Am. Chem. Soc. 115 (1993) 1804.
[10] V.K. Yachandra, K. Sauer, M.P. Klein, Chem. Rev. 96 (1996) 2927.
[11] S. Mukhopadhyay, R.J. Staples, W.H. Armstrong, Chem. Commun. (2002) 864.
[12] R. Guilard, S. Brandes, A. Tabard, N. Bouhmaida, C. Lecomte, P. Richard, J.M.
Latour, J. Am. Chem. Soc. 16 (1994) 10202.
[
[
[
[
13] S.J. Lippard, Angew. Chem. Int. Ed. Engl. 27 (1988) 344.
14] R. Sukla, P.K. Bharadwaj, Indian J. Chem. 32A (1993) 767.
15] B.R. Havinale, I.B. Pujar, Indian J. Chem. 20A (1981) 1130.
16] J.L. Seela, K. Folting, R.J. Wang, J.C. Huffman, G. Christou, H.R. Chang, D.N. Hen-
drickson, Inorg. Chem. 24 (1985) 4454.
[17] S. Pal, P. Ghosh, Chakravorty, Inorg. Chem. 24 (1985) 3704.
[18] J.D. Crowley, D.A. Traynor, D.C. Watherburn, Met. Ions Biol. Syst. 37 (2000) 209.
[19] S. Iwata, J. Barber, J. Curr. Opin. Struct. Biol. 14 (2004) 447.
[20] K.A. Campbell, E. Yikilmaz, C.V. Grant, W. Gregor, A.F. Miller, R.D. Britt, J. Am.
Chem. Soc. 121 (1999) 4714.
[
21] B.R. Stults, R.S. Marianell, V.W. Day, Inorg. Chem. 14 (1975) 722.
◦
Fig. 8. Optical transmittance of (a) pure ZnO thin films, post-heated at 550 C (b)
ZnO thin films modified with manganese complex 2.
[22] E. Larson, M.S. Lah, X. Li, J.A. Bonadies, V.L. Pecoraro, Inorg. Chem. 31 (1992)
373.
[
[
23] R.L. Dutta, R.K. Ray, J. Indian Chem. Soc. LIV (1977) 1096.
24] K. Wieghardt, U. Bossek, B. Nuber, J. Weiss, J. Bonvoisin, M. Corbella, S.E. Vitols,
J.J. Girerd, J. Am. Chem. Soc. 110 (1988) 7398.
other hand, the zinc oxide thin film nanoparticles modified by
[
[
[
[
25] K.L. Zhang, Y. Xu, Y. Song, Y.G. Zhan, Z. Wang, X.Z. You, J. Mol. Struct. 570 (2001)
[
Mn(h5 mb pn)(H O)(Py)][PF ] complex had a nanometer size
2 2 6
137.
and aggregated morphologies (Fig. 7). The UV–vis transmittance
spectra of pure zinc oxide thin film (Fig. 8a) and zinc oxide thin
26] S. Naskar, S. Biswas, D. Mishr, B. Adhikary, L.R. Falvello, T. Soler, C.H. Schwalb,
S.K. Chattopadhyay, Inorg. Chim. Acta 357 (2004) 4257.
27] C.A. McAuliffe, A. Nabhan, R.G. Pritchard, M. Watkinson, M. Bermejo, A. Sousa,
Acta. Crystallogr. Sect. C 50 (1994) 1676.
film modified by [Mn(2h5 mb) pn)(H O)(Py)][PF ] complex is
2
2
6
shown in Fig. 8b. A red shift is observed when zinc oxide thin film
28] S.N. Li, J. Li, Z.X. Tang, Z.Y. Zhou, Acta. Chim. Sinica (Chin.) 59 (2001) 78.
is modified by [Mn(2h5 mb) pn)(H O)(Py)][PF ] complex. Surface
[29] S. Biswas, K. Mitra, C.H. Schwalbe, C.R. Lucas, S.K. Chattopadhyay, B. Adhikary,
Inorg. Chim. Acta 358 (2005) 2473.
2
2
6
−
10
mol cm2 has been reported
coverage of approximately 1 × 10
[
30] E. Gallo, E. Solari, N. Re, C. Floriani, A. Chiesivilla, C. Rizzoli, J. Am. Chem. Soc.
19 (1997) 5144.
for monolayer of complexes lying flat on a substrate. Values that
we have obtained for manganese(III) complexes on zinc oxide
thin film are very close to that reported values for cobalt complex
1
[31] C. Chen, D. Huang, X. Zhang, F. Chen, H. Zhu, Q. Liu, C. Zhang, D. Liao, L. Li, L.
Sun, Inorg. Chem. 42 (2003) 3540.
[32] T. Fukuda, F. Sakamoto, M. Sato, Y. Nakano, X.S. Tan, Y. Fujii, Chem. Commun.
−11
2
(
7.0 × 10
mol cm ) [51–54].
(
1998) 1391.
[
33] J. Li, S.M. Yang, F.X. Zhang, Z.X. Tang, Q.Z. Shi, Q.J. Wu, Z.X. Huang, Chin. J. Inorg.
Chem. 16 (2000) 84.
4
. Conclusion
[
[
34] S. Biswas, K. Mitra, B. Adhikary, C.R. Lucas, Trans. Met. Chem. 30 (2005) 586.
35] R.M. Issa, S.A. Amer, I.A. Mansour, A.I. Abdel-Monsef, J. Therm. Anal. Calorim.
90 (2007) 261.
We have prepared Mn(III) complexes of Me-salpn in which the
[
[
[
36] M.J. Carter, D.P. Rillema, F. Basolo, J. Am. Chem. Soc. 96 (1974) 392.
37] F. Donald, F. Averill, R. Broman, Inorg. Chem. 17 (1978) 3389.
38] G.S. Patterson, R.H. Holm, Bioinorg. Chem. 4 (1975) 257.
tetradentate Schiff base ligand, Me-salpn, adopts a trans configu-
ration and the two ancillary ligands are therefore trans. The cyclic
voltammograms of both complexes demonstrate that both com-
[39] M.H. Habibi, M. Nasr-Esfahani, Inter. J. Photoenergy (2008) 628713.

M.H. Habibi et al. / Spectrochimica Acta Part A 79 (2011) 666–671
671
[
[
[
[
[
[
40] M.H. Habibi, N. Talebian, Thin Solid Films 515 (2006) 1461.
41] M.H. Habibi, N. Talebian, J.H. Choi, Dyes Pigments 73 (2007) 103.
42] M.H. Habibi, N. Talebian, Dyes Pigments 73 (2007) 186.
43] M.H. Habibi, I. Asadi-farsani, Desalination Water Treatment 22 (2010) 204.
44] T. Higashi, Shape Program for Absorption, Rigaku Corporation, Tokyo, 2005.
45] M.C. Burla, R. Caliandro, M. Camalli, B. Carrozzini, G.L. Cascarano, L. De Caro, C.
Giacovazzo, G. Polidori, R. Spagna, J. Appl. Crystallogr. 38 (2005) 381.
46] G.M. Sheldrich, SHELXL97, University of Gottingen, Germany, 1997.
47] M.H. Habibi, M.J. Khaledi, Nanomaterial (2008) 356765.
[49] F.M. Hwang, H.Y. Chen, P.S. Chen, C.S. Liu, Y.C. Chi, C.F. Shu, F.L. Wu, P.T. Chou,
S.M. Peng, G.H. Lee, Inorg. Chem. 44 (2005) 1344.
[50] M.A. Baldo, M.E. Thompson, S.R. Forest, Nature 403 (2000) 750.
[51] I.A. Akinbulu, S. Khene, T. Nyokong, Electrochim. Acta 55 (2010)
7085.
[52] J.H. Zagal, M.A. Guilppi, C. Depretz, D. Lelievre, J. Porphyr. Phthalocya. 3 (1999)
355.
[53] N. Kobayashi, P. Janda, A.B.P. Lever, Inorg. Chem. 31 (1992) 5172.
[54] M. Ebadi, Electrochim. Acta 48 (2003) 4233.
[
[
[
48] T.T. Wang, J.M. Xie, C.K. Xia, Y.L. Wu, J.J. Jing, Anorg. Allg. Chem. 636 (2010)
1
580.