Tetra- And poly-nuclear Cd(ii) complexes of an N3O4Schiff base ligand: Crystal structures, electrical conductivity and photoswitching properties

Article abstract of DOI:10.1039/d0nj03325a

Two new Cd(ii) complexes, [Cd4L2(NO3)2(μ1,1-N3)2(CH3OH)2] (1) and {[Cd2L(IPA)]2·(CH3OH)}n (2), have been synthesized by using a multidentate Schiff base ligand H2L (N,N′-bis(3-methoxysalicylidene)-diethylenetriamine) and two bridging co-ligands azide and

Full text of DOI:10.1039/d0nj03325a

View Article Online
View Journal
NJC
New Journal of Chemistry
Accepted Manuscript
A journal for new directions in chemistry
This article can be cited before page numbers have been issued, to do this please use: T. K. Ghosh, S.
Jana, S. Jana and A. Ghosh, New J. Chem., 2020, DOI: 10.1039/D0NJ03325A.
Volume 42
This is an Accepted Manuscript, which has been through the
Number
6
21 March 2018
Pages 3963-4776
Royal Society of Chemistry peer review process and has been
accepted for publication.
NJC
New Journal of Chemistry
rsc.li/njc
A journal for new directions in chemistry
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1144-2546
PAPER
Chechia Hu, Tzu-Jen Lin et al.
Yellowish and blue luminescent graphene oxide quantum dots
prepared via a microwave-assisted hydrothermal route using
H2O2 and KMnO4 as oxidizing agents
rsc.li/njc

Page 1 of 25
New Journal of Chemistry
1
2
3
4
5
6
7
8
9
View Article Online
DOI: 10.1039/D0NJ03325A
Tetra- and poly-nuclear Cd(II) complexes of an N3O4 Schiff base
ligand: Crystal structures, electrical conductivity and
photoswitching property
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Tanmoy Kumar Ghosh,a Sumanta Jana,b Subrata Janaa and Ashutosh Ghosha*
aDepartment of Chemistry, University College of Science, University of Calcutta, 92, A.P.C.
Road, Kolkata 700 009, India, E-mail address: ghosh_59@yahoo.com
bDepartment of Chemistry, Jadavpur University, Jadavpur, Kolkata 700032, India
Abstract
Two
new
Cd(II)
complexes,
[Cd4L2(NO3)2(μ1,1-N3)2(CH3OH)2]
(1)
and
{[Cd2L(IPA)]2∙(CH3OH)}n (2) have been synthesized by using a multidentate Schiff base
ligand H2L (N,N ′ -bis(3-methoxysalicylidene)-diethylenetriamine) and two bridging co-
ligands azide and isophthalic acid (IPA), respectively. Single crystal structure analysis shows
that complex 1 has tetranuclear structure whereas complex 2 forms a 1D polymer. The
photoswitching behavior of both complexes has been measured under 1 Sun illumination. A
significant enhancement of frequency ~65 Hz was observed for complex 2 but for complex 1
no such enhancement was detected. To gain a detail understanding about charge transport
mechanism of the complexes, the effective carrier mobility, transit time, carrier concentration
and diffusion length have been estimated considering Schottky Barrier Diodes (SBD)
characteristics. The charge transport properties of complex 2 were found to be superior to
complex 1. Complex 2 showed increased conductivity from 5.4×10-8 S cm−1 to 135 × 10−8 S
cm−1 in the presence of light.
Introduction
Over the last few years, the scientific research based on Coordination Polymer (CP) have
attracted significant attention due to not only their fascinating structural diversity but also
their versatile potential applications in several fields of chemistry and materials science such
as gas storage and separation, catalysis, ion exchange, drug delivery, fuel cell, barrier diode,
photoelectric material, magnetism and sensing applications.1-23 Generally CPs are prepared by
1

New Journal of Chemistry
Page 2 of 25
1
2
3
View Article Online
the reaction of metal salts or metal-ion clusters with the multidentate bridgDinOgI: 10o.1r0g39a/nD0icNJ03325A
ligands.24,25 The structural diversity of the CPs can be tuned by altering the metal centres, the
organic linkers and also by the reaction pathway.26,27 The potential applications of CPs by
exploiting their large surface area and porosity have been studied comprehensively during the
last decades but the prospect of CPs to be used as photovoltaics and optoelectronic devices is
still remain unexplored to a great extent.28,29 The electronic properties of CPs can also be
controlled by using appropriate metal ions and organic linkers like other performance of
CPs.6,30 Recently, some literature reports showed that CPs prepared from d10 metal ions (Zn2+,
Cd(II)) with different benzene dicarboxylate linkers have the ability to be used for the
fabrication of optoelectronic devices like Schottky barrier diodes (SBD).16,31 A Schottky
diode is a diode that has a low forward voltage drop and a very fast switching ability. It is
formed by the junction of metal and semiconductor. Some CP based devices under dark and
illumination conditions can show non-linear rectifying behavior i.e. behave like Schottky
barrier diodes. There are several reports where CPs are successfully employed as diodes that
harvest visible light and show enhanced photocurrent generation.32-34 Inspired by the above
facts, several groups including ours have synthesized Cd(II) based CPs which exhibit
photoswitching properties and electrical conductivity.35-37 The structure property
relationships of the CPs have also been explored which is very important for the fabrication
of these types of optoelectronic devices.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
In the present work, we have synthesized two CdII complexes [Cd4L2(NO3)2(μ1,1-
N3)2(CH3OH)2] (1) and {[Cd2L(IPA)]2∙(CH3OH)}n (2) using a multidentate Schiff base ligand
H2L (N,N′-bis(3-methoxysalicylidene)-diethylenetriamine) and two bridging co-ligands azide
and isophthalic acid (IPA), respectively. Complex 1 possesses discrete tetranuclear structure
whereas complex 2 is a one-dimensional coordination polymer (1D CP). The photo-switching
behavior and electrical conductivity of both the complexes have been measured in order to
comprehend and portray a proper comparison between the electrical properties of discrete
multinuclear complex and a one-dimensional coordination polymer. A substantial on-off ratio
(65 Hz) for photo switching behavior has been observed for complex 2 but for complex 1 no
such enhancement is detected. To gain insight into the charge transport mechanism of the
complexes, the effective carrier mobility, transit time, carrier concentration and diffusion
length have been estimated considering Schottky barrier diodes (SBD) characteristics. An
2

Page 3 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
improvement of charge transport properties has been noticed for polymericDcOoI: m10.p10l3e9x/D02NJ03325A
5
6
compared to complex 1.
7
8
Experimental Section
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Synthesis of Schiff base ligands (H2L)
The Schiff base ligand (H2L = N,N'-bis(3-methoxysalicylidene)diethylenetriamine) was
synthesized in our laboratory by following the methods reported earlier.38,39
Synthesis of the complex [Cd4(L)2(NO3)2(μ1,1-N3)2(CH3OH)2] (1)
A methanolic solution (20 mL) of Schiff base ligand (1 mmol, 0.371 g) was added to a
methanolic solution (15 mL) of Cd(NO3)2·4H2O (2 mmol, 0.617 g) with constant stirring.
Then an aqueous solution (1 mL) of sodium azide (0.065 g, 1 mmol) was added to the above
mixture. The resulting solution was stirred for further 2 h and then the solution was left at
open atmosphere. Diffraction quality light yellow colored single crystals were obtained after
four days on slow evaporation of the solvent.
Yield: 0.511 g (70%) C42H54Cd4N14O16 (1460.63). Calculated C, 34.54; H, 3.73; N, 13.43;
Found C, 34.47; H, 3.81; N, 13.54; IR: ν(N–H) = 3051 cm–1, ν(C=N) = 1633 cm–1, ν(N3)= 2057
cm–1, ν(NO3) = 1384 cm–1.
Synthesis of the complex {[Cd2(L)(IPA)]2∙(CH3OH)}n (2)
To a methanolic solution (20 mL) of Schiff base ligand (1 mmol, 0.371 g), solid
Cd(NO3)2·4H2O (2 mmol, 0.617 g) was added and stirred for 10 min. A solution of
isophthalic acid (IPA, 0.166 g, 1 mmol) was prepared separately in 10 mL distilled water and
280 μL triethylamine (2 mmol) was added to it and mixed well. The solution was then added
drop wise to the above mentioned methanolic solution and stirred for 45 min. Light yellow
colored single crystals for X-ray diffraction were obtained by slow diffusion of diethyl ether
into the solution.
Yield: 0.503 g (65%) C28.5H29Cd2N3O8.5 (774.35). Calculated C, 44.20; H, 3.77; N, 5.43;
Found C, 44.30; H, 3.68; N, 5.35; IR: ν(N–H) = 3220 cm–1, ν(C=N) = 1640 cm–1, ν(NO3) = 1384
cm–1, ν(s+as)(COO-) = 1387, 1557 cm–1.
3

New Journal of Chemistry
Page 4 of 25
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
Physical measurements
5
6
7
8
IR spectra, Elemental analyses, UV-vis spectra and Powder X-ray of complexes 1 and 2 have
been performed as previously reported.37,39
9
Thin film fabrication from the precursor complexes
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
In this paper thin films of precursor complexes have been synthesized onto properly cleaned
ITO glass substrate (resistance ~ 10 Ω/sq cm) of surface area 2.0 cm × 1.0 cm by spin-coating
of precursor solution. For the preparation of working solution, precursor complex is
intimately mixed with methanol in the ratio 1:5. With the help of micro-pipette few drops of
working solution were allowed to fall onto the centre of a stationary conducting ITO
substrate. Then solution was spin-coated at 1500 rpm for 2 minutes and it is repeated for 3
times. The resulting film was taken out and kept in desiccators. The same procedure was
repeated for capped complex precursor. The thicknesses of the film were measured to ~ 400
nm by surface profilometer (Bruker contour G).
X-ray Crystallographic data collection and refinement
Crystallographic data of single crystals of complexes 1 and 2 have been collected as
previously reported.39 The structure was solved by direct methods and refined by full-matrix
least squares on F2 using the Shelxl16-6 package and Olex2 program.40,41 Absorption
corrections were carried out using the SADABS program.42 C10B and C11B atoms in
complex 2 were disordered and was refined considering a model in which two different sites
were located for the carbon atoms. Data collection, structure refinement parameters and
crystallographic data for complexes 1 and 2 are given in Table 1. CCDC 1975601 1975602
contain the supplementary crystallographic data for this paper.
4

Page 5 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Scheme 1. Synthesis of complexes 12.
Results and discussion
Syntheses of the complexes
The Schiff base ligand, N,N'-bis(3-methoxysalicylidene)diethylenetriamine (H2L) was
prepared following the literature method by 1:2 condensation of diethylenetriamine and o-
vanilin in methanol. The Schiff base ligand (H2L) on reaction with Cd(NO3)2·4H2O and
sodium azide in 1: 2: 1 ratio resulted in a tetra-nuclear complex, 1 (Scheme 1). On the other
hand, when we used deprotonated isophthalic acid instead of sodium azide, we got
polynuclear complex 2. The phase purity of synthesized complexes has been checked by
comparing the experimental PXRD pattern of the bulk products with the simulated XRD
pattern from single crystal X-ray diffraction (Fig. S1, ESI).
5

New Journal of Chemistry
Page 6 of 25
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
IR spectra of complexes
5
6
7
8
Besides elemental analyses, both complexes were initially characterized by the IR spectra. A
strong and sharp band due to the azomethine ν(C=N) group of the Schiff base appears at
around 1635 cm−1 for both of the complexes 1 and 2.43 Complexes 1 and 2 exhibit a bands
around 3170 cm−1 confirming the presence of the N−H group.43 The presence of azido and
nitrate anion in complex 1 is confirmed by the appearance of strong and sharp peaks at 2060
cm−1 and 1384 cm−1 respectively.44 Two sharp peaks at 1557 and 1387 cm−1 appear for the
asymmetric and symmetric stretching of −COO−, respectively, for complex 2.45
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Description of the structures
Fig. 1 ORTEP diagram of complex 1 with 20% ellipsoid probability. Hydrogen atoms are not
shown for clarity.
The structure of complex 1 is shown in Fig. 1. It is a centro-symmetric discrete tetra-nuclear
complex, in which two dinuclear units are bridged by two 1,1- azide co-anions. The
asymmetric unit of complex 1 contains one Schiff base ligand, two Cd(II) ions, one methanol
molecule, one azide and one nitrate co-anions. Cd1 centre is hexa-coordinated and Cd2 centre
is octa-coordinated. Cd1 centre is coordinated by five donor atoms N1, N2, N3, O1, O2 from
ligand L2- and O5 from a methanol molecule. Cd2 centre is coordinated by four oxygen atoms
O1, O2, O3, O4 from the ligand L2-, O6, O7 from the nitrate co-anion and N5, N5* from the
symmetry related(1-x,1-y,1-z) azide co-anion. The Cd(II)N(amine) distance is 2.508(3) Å
whereas Cd(II)N(imine) distances are 2.65(3) and 2.289(3) Å. The Cd(II)O(phenoxo)
6

Page 7 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
distances are shorter at 2.266(2) and 2.305(3) Å than Cd(II)O(methoxo) distances at
5
6
7
8
2.459(3) and 2.518(3) Å. All these distances are very similar to those observed for other
structurally characterized Cd(II) complexes of this ligand.46,47 The Cd(II)O(nitrate)
distances are 2.419(5) and 2.767(7) Å. Selected bond lengths and bond angles of complex 1
are given in Table S1, ESI. The hydrogen atom, H5 attached to oxygen atom, O5, forms
hydrogen bond with the nitrate oxygen atom (O7), details of which are given in Table S3,
ESI.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Fig. 2 ORTEP diagram of complex 2(A) with 20% ellipsoid probability. Hydrogen atoms are
not shown for clarity.
In complex 2, there are two dinuclear units (A and B) in the asymmetric unit having
equivalent structure with slight difference in bond angles and bond lengths. Each unit is a part
of a polymeric chain structure formed by linking the dinuclear units by bridging isophthalate
(IPA) co-ligand. A perspective view of molecule A together with the atom numbering scheme
is shown in Fig. 2 and that of B is shown in Fig. S2, ESI. The Cd1 centre is hexa-coordinated
being bonded by three nitrogen and three oxygen atoms, N1A, N2A, N3A, O1A, O2A from
the ligand L2- and O5A from isophthalate co-ligand. The Cd2 centre is hepta-coordinated
being bonded by seven oxygen atoms, O1A, O2A, O3A, O4A from the ligand and O6A,
O7A, O8A from isophthalate co-ligand. The Cd(II)O(phenoxo) bond lengths are within the
range of 2.227(3)2.303(3) Å. The Cd(II)N(amine) bond length are 2.520(3) and 2.467(5)
Å, whereas the Cd(II)N(imine), Cd(II)O(methoxo) and Cd(II)O(carboxylate) bond
lengths are lies in the range of 2.285(6)2.315(6) Å, 2.569(4)2.700(5) Å and
7

New Journal of Chemistry
Page 8 of 25
1
2
3
View Article Online
2.210(4)2.309(4) Å, respectively. Selected bond lengths and bond angles of coDmOpI:l1e0x.10329/aDr0eNJ03325A
given in Table S2, ESI. In this complex, the deprotonated isophthalic acid bridges three
Cd(II) centres via (1κ2O,O:2κO,O ′ ) mode where both oxygen atoms of one carboxylate
bridges two Cd(II) centres of one dinuclear unit, while the other carboxylate bridges the
Cd(II) centre of a symmetry related dinuclear unit. Thus, each IPA acts as a 3-bridging
ligand to form the polymeric chain (Fig. 3). The hydrogen atom, H2AA, attached to nitrogen
atom, N2B, forms intramolecular hydrogen bonding interaction with the oxygen atom, O9 of
solvent methanol molecule and the hydrogen atom H3AA, attached to the O9, forms
hydrogen bonding interaction with the carboxylate anion oxygen atom O5B. The H-bonding
parameters are given in Table S3, ESI.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Fig. 3 Polymeric chain of complex 2 built by units A. A closely comparable chain is formed
by units B.
Fig. 4 UV-Vis spectra (thin film) of complexes 1 and 2, inset: band gap
8

Page 9 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
5
6
Optical study
7
8
9
Fig. 4 shows the UV-Vis absorption spectra of both complexes 1 and 2 (thin films). The band
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
gap energy was evaluated from the absorption spectra using the following relation:
(αhν) ∞ (hν-Eg)n
(1)
Where, Eg is the energy band gap, α is the absorption coefficient, n is a coefficient having the
value ½ for allowed direct band-to-band transition. The Tauc plot (αhν)2 vs.(hν) is shown as
the inset of Fig. 4. Optical band gap was calculated from this relation by plotting (αhν)2
versus hν and extrapolating the linear portion of the curve to the x-axis; α being the
absorption coefficient and hν, the photon energy. The band gap (Eg) was calculated to be 2.98
and 2.90 eV for complexes 1 and 2, respectively. Wide band gap of this material is a good
signature for opto-electronic properties. Slight decrease of band gap for complex 2 may be
due to its polymeric nature.48 Complex 2 ensures surface modification by lowering band
width (d) of valence band (VB) and conduction band (CB). As a result, number of excitons in
VB and CB increases and it leads to lowering of band gap energy. The absorption spectra of
complexes 1 and 2 (in methanol solution) are given in supporting information (Fig. S3, ESI).
Both complexes show a sharp rise in absorption from 400 nm and maximum absorption
occurs in the UV region at 350 nm due to n-* transition.39
Fig. 5 (a) Thin film FESEM images of complex 1 and (b) complex 2.
9

New Journal of Chemistry
Page 10 of 25
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
5
6
Morphological analysis of thin films
7
8
9
Fig. 5 (a) represents FESEM image of complex 1. It shows granular morphology along with
randomly oriented agglomerated particles. Average grain size of discrete particle has been
estimated to be 50-55 nm. However, agglomerated particles form their own moiety make
overall morphology “uneven”. FESEM image of complex 2 is represented in Fig. 5b. It
shows highly porous fleshy structure in combination with islands and coarse wells. Each
island is composed with uniformly distributed spherical grains. The wells and islands are
distinct but the grains are invisible due to formation of islands which increases the surface to
a large extent. These wells can be regarded as trapped zones for electrons.49 Now applying a
fixed potential/frequency stimulates the trapped electrons and electrons get released from
trapped zones and shows current amplification (photoexcitation).
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Fig. 6 Photocurrent responses of (a) complex 1 and (b) complex 2 (c) Photocurrent versus
time (I–t) plots of complexes 1 and 2.
10

Page 11 of 25
New Journal of Chemistry
1
2
3
4
5
6
7
8
9
View Article Online
DOI: 10.1039/D0NJ03325A
Surfaceof Cd
complex
Polymer
(a)
POLYMER
CB
M
qv1
CB
qv2
U
L
T
I
M
E
T
E
R
-------------------------------
EF
------------------------------
EF
Electrons
Graphitecontact
I
T
O
L
I
Surfacestates
VB
Surfacestates
VB
G
H
T
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
d1
d1
Holes
d2
d2
Thin Film
(b)
(c)
Fig. 7 (a) Schematic of frequency switching study (b) Band diagram of complex 1 and (c)
complex 2.
Frequency switching:
To measure the switching behaviour of synthesized materials, light dependent exciton
generation was studied where top and bottom contacts were made from deposited material
and ITO layer using colloidal silver paste. An external light source of intensity 1 Sun was
used to fall on the ITO so that it could pass the film. From the response ratio curve (Fig. 6b),
it could be observed that as soon as the light hit the material the frequency increased to ~ 65
Hz and became steady for 50 seconds. This frequency is oscillation frequency and it goes to
‘zero’ as soon as light is chocked. Switching off the light allowed the excitons to be at ground
state and resulted in their fast recombination; hence, no pulse/frequency was generated at this
stage. Repeatability of this experiment was viewed for more than 30 cycles indicating steady
nature of the polymer material. Same arrangement was repeated for complex 1 but no
significant response was detected (Fig. 6a). The transient photocurrent with respect to time
was measured under light illumination of 100 mW cm-2 at 1 V, which is shown in Fig. 6c. To
compare the photosensitivity (A/W) of each device individual dark currents were subtracted
from light currents. It has been observed that the device fabricated with complex 1 showed
photosensitivity 1.18. Whereas, the device made from complex 2 showed a high
photosensitivity 5.41. These photosensitivity values are consistent with the data obtained
from I-V measurement (Table 2). In general photoresponse is a speedy electron transfer
process where photoexcited electrons are transferred from the highest occupied molecular
orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). High photosensitivity
of complex 2 indicates efficient photogenerated electron−hole separation and retardation of
recombination process. The phenomenon could also be explained by introducing surface state
11

New Journal of Chemistry
Page 12 of 25
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
energy concept observed in polymer complexes.49 Polymer encapsulation causes surface
5
6
7
8
modification of the material and lowers down the width (d) of the depletion region (Fig.
7(c)). As a result, the number of separated electron-hole pairs (excitons) in between VB and
CB increases which leads to increase in exciton related emission by reducing recombination
process.49 The increased number of excitons results high frequency switching behavior for
complex 2 and suggest that the complex can be a promising candidate for photo switch. Fig.
7(b) shows the band energy diagram of complex 1 where no such surface modification
occurs.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Electrical Characterization: I-V measurement
Two-probe I-V measurement was carried out under dark and light illumination (1 Sun)
condition from potential −1 to +1 V taking Al as metal contact. Fig. 8 (a) shows I-V nature
for complex 1. Nonlinear nature of I−V curve shows good rectifying behaviour which is an
indication of Schottky barrier diode (SBD). The non-linear I-V characteristic also indicates
formation of depletion region in between the interface. In forward bias thin films of both
complexes (complexes 1 and 2) show enhanced rectifying behaviour under illumination. In
case of complex 2, the ratio of on/off was calculated to be 2.37 and 12.84 under dark and
light illumination, respectively (Table 2). It indicates high rectifying property of the diode
which is comparable to the others of same type.35,50-52 Room temperature conductivities of
complexes 1 and 2 were evaluated from I−V curves. It has been observed that for both
complexes light illumination results in increase of conductivity compared to dark condition
(Tables 3 and 4). Generally thin film faces intrinsic defects by atmospheric oxygen or gas
molecules, which lead to band bending from its bulk counterpart and thereby affect on
electronic transition. The defects become high at the grain boundaries of the nanoparticles
and causes trapping of electrons. By applying certain bias, these trapped zones become
saturated and electrons get free. Therefore, an enhanced current density is observed in
forward bias. In reverse bias, opposite phenomenon is found to be happened. Reversing the
bias decreases the electrostatic attraction of trapped zones and results increase in an leakage
current densitiy. The current generated in the reverse bias comes from the loss of junction
properties by free minority carriers which in turn raise the reverse saturation current. For
both complexes a detail SBD related parameter like photosensitivity, conductivity, ideality
factor, diffusion coefficient, effective mobility etc. were calculated (Table 3 and 4). The
better semiconducting feature of the polymeric complex 2 can be attributed to the charge
12

Page 13 of 25
New Journal of Chemistry
1
2
3
4
delocalization throughout the polymeric chain via highly π conjugated dicarboxylic VaiecwiAdrticle Online
DOI: 10.1039/D0NJ03325A
5
6
7
8
linkers. Further, the supramolecular interactions through closely spaced polymeric chains can
also improve the semiconducting property of complex 2 as charge can move through non-
covalent supramolecular contacts (e.g. CHπ, ππ) via “hopping transport” phemenon.53
But in case of complex 1, which is a discrete species and charge may move only through
noncovalent supramolecular contacts (e.g. C-H…π, π…π) via “hopping transport”
phenomenon” giving rise to weak semiconducting ability.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Fig. 8 I–V characteristic curve of (a) ITO/complex 1/Ag thin film and (b) ITO/ complex 2/Ag
thin film.
Electrical characterization and photosensitivity
The current voltage characteristics of complexes 1 and 2 based devices are shown in Fig. 8. It
exhibits a highly non-linear rectifying Schottky diode behaviour. The non-linearity of the I–V
curve indicates non-ohmic nature which is highly influenced by incident radiation. Complex
2 shows linearity of current axis at low reverse bias but at higher bias due to high series
resistance current no longer becomes linear. The rectification ratios under dark and photo
illumination have been calculated to be 3 and 6, respectively for complex 1 and 2.51 and 17
respectively for complex 2. Thus, an enhanced rectification in presence of light is obvious for
complex 2. To understand the charge transport mechanism, thermoionic emission theory was
introduced to analyze the I–V curve using Cheung standard equation for Schottky diodes.54
13

New Journal of Chemistry
Page 14 of 25
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
where I; forward current, I0; saturation current (reverse), V; applied potential, q; electronic
5
6
charge, k; Boltzmann constant, T; absolute temperature, η; ideality factor.
7
8
The intercept of ln(I) where V = 0 gives I0 from the following equation
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(3)
Here, A stands for diode area, ΦB represents barrier potential height and A* is the Richardson
constant. For all the measurements effective diode area was 7.065×10-2 cm2 and the value of
Richardson constant was considered as 32 A K-2 cm-2.
To determine other device parameters, following equations were used.55
(4)
Series resistance (Rs) was calculated from the following equations (5 and 6).
(5)
H(I) = IRS + ηΦB
(6)
Equation (4) represents straight line and indicates downward-curvature region of the forward
bias where Rs predominates. Thus, from the slope of dV/dlnI vs. I (Fig. 9a and 9b) RS is
calculated and intercept of the same plot at y axis gives ideality factor (η). The η values under
dark and illumination were calculated to be 2.58 and 1.46 for complex 1 and 2.5 and 1.24 for
complex 2, respectively. Analyzing η values, it can be concluded that the MS junction of
complex 2 is less deviate from ideality. Hence complex 2 is more suitable for device
fabrication. This deviation comes from in-homogeneities in barrier height (ΦB), mismatch of
interfacial states and series resistance in the junction.56 Using the measured η value, H was
calculated from equation (5). Plot of H (I) vs. I also represents a straight line whose intercept
at y-axis becomes equal to ηΦB (Fig. 10). The measured barrier height (ΦB), ideality factor (η)
and series resistance (RS) under the dark and illumination etc. for the MS junction of complex
1 and complex 2 are separately enlisted in Table 3 and 4. From the Tables it is clear that the
series resistance (RS) for both complexes obtained from two different methods using
Cheung’s functions are in concurrence with each other.
14

Page 15 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Fig. 9 dV/dln I vs. I plot under dark and illumination conditions for (a) complex 1 and (b)
complex 2.
Fig. 10 H (I) vs I graph under dark and illumination condition for (a) complex 1 and (b)
complex 2 thin film devices, respectively.
Fig. 11 Plot of log (I) versus log (V) for complex 2 under (a) dark and (b) illumination.
15

New Journal of Chemistry
Page 16 of 25
1
2
3
View Article Online
To gain better perceptive of the MS junction, consideration of interface carrierDtOraI: n10s.1p0o39r/tD0isNJ03325A
useful. Fig. 11 represents the log-log (I-V) plot of complex 2. It implies existence of different
conduction regions. We can segregate it into three distinct linear regions considering different
slopes. Each partition has unique feature correspond to electron transportation. Presence of
interfacial deep wells at M-S junction is responsible for alteration the slopes which in turn
alters the carrier concentration of individual partition. At low bias i.e. region-I, current
increases proportionally with voltage, confirms the ohmic nature of the device. Therefore,
region-I is attributed to thermionic emission where current is controlled by the bulk electrons
of the material, rather than the injected free carriers.57–59 After that, I–V curve proceeds
smoothly and follows power law (I ∞ Vn), which is assigned as region II. In this region, the
current is governed by space charge limit current (SCLC) where current becomes directly
proportional to the square of the applied potential (I ∞ V2).60,61 Due to thermionic oscillation
injected carriers become highly activated and started to spread by creating a space charge
region in conduction path. Just behind the region (II), current becomes more steeper and at
further higher bias, the current increases sharply because of excessive electron accumulation
which triggers to exceed the ‘trap-filled’ limit of the diode easily.57 So, it can be concluded
that region I is devoted for charge transportation and regions II and III can be categorised as
SCLC and trap free SCLC at their respective forward bias. To understand the charge
transport mechanism precisely, region II has been selected to apply SCLC on it. Effective
carrier mobility at region II is measured from the slope of I vs V2 (Fig. 12) by using the Mott-
Gurney equation62
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
( )
(7)
where J, ε0 and εt represents current density, vaccum permittivity dielectric constant,
respectively. The effective carrier mobility (µeff) was calculated to 1.49 ×10-8 cm2 V-1 s-1,
which is at par for the compounds. Dielectric constant (DC) was measured under constant
bias at saturation capacitance from capacitance vs frequency plot. The variation of the
capacitance (c) as a function of the frequency (f) at constant bias potential was shown in Fig.
S4, ESI. The room temperature capacitance of the complex is found to be frequency
dependent at relatively lower frequencies. The capacitance decreases with increasing
frequency and becomes saturated at higher frequency and the saturation capacitance is found
to be 20 x 10-12 F. The following conventional equation is used to measure dielectric
constant.63
16

Page 17 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
5
6
7
8
9
Where, ε0 is the permittivity of free space, εr is the relative permittivity of the complex, C is
the capacitance (at saturation) and L is the thickness and A is effective area of the film. By
using capacitance value (saturation) the DC comes out to be 5.674. Other device parameters
such as carrier concentration (N), carrier lifetime (t) and diffusion length (LD) were estimated
using the following set of equations.64
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(9)
(10)
(11)
Activity of any SBD can be judged by its diffusion lengh (LD). High value of LD ensures
better device performance.
Fig. 12 I vs V2 plot for complex 2 device in (a) dark and (b) illumination
From the slope of log I vs log plot of region II (Fig. 11) carrier lifetime (t) was calculated. It
has been found that for complex 2 carrier life time is shorter in comparison to complex 1. It is
a good signature for device fabrication with complex 2. Diffusion coefficient was measured
following Einstein–Smoluchowski equation.65,66
(12)
The obtained values of the diode and transport parameters are listed in Table 3 and Table 4
for complexes 1 and 2, respectively.
17

New Journal of Chemistry
Page 18 of 25
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
Conclusion
5
6
7
8
We have reacted the flexidentate ligand, N,N′-bis(3- methoxysalicylidene)diethylenetriamine
(H2L), with cadmium nitrate in presence of bridging co-anions, azide or isophthalate. The
azide ion yields a discrete tetra-nuclear complex whereas aone-dimentional polymeric
complex is produced with bridging isophthalate. We have explored the effect of this
structural variation on the optoelectrical properties of the synthesized complexes.
Interestingly, it has been found that only polymeric complex 2 shows considerable photo
switching phenomenon. In complex 2 mobilization of charge carriers takes place via highly π
conjugated organic linkers and the 1D CP ensures surface modification which in turn
increases the number of excitons in between VB and CB. The result is the substantial
reduction of recombination process and therefore material shows enhanced current intensity
under the irradiance of light. Moreover, the fabricated devices using complexes 1 and 2
exhibit a non-linear rectifying behavior under dark and illumination conditions at the applied
potential of ±1.0 V. Several device parameters have been measured and the charge transport
properties have been analyzed on the basis of the Schottky diode mechanism. The estimated
mobility, lifetime, carrier diffusion length, ideality factor clearly show that the device
performance of the polymeric complex is much better compared to the discrete complex and
it would be a promising material for light sensing electronic devices as well as for diode
fabrication.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Supporting Information
CCDC 1975601 1975602 contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif. bond lengths and angles of complexes 1 and 2,
PXRD pattern of complexes 1 and 2, UV-Vis spectra of complexes 1 and 2 in methanol
solution, ORTEP of complex 2B, Capacitance vs. Frequency plot, Dielectric vs. Frequency
plot for complex 2.
Acknowledgement
T. K. G. is thankful to the University Grants Commission (UGC), New Delhi, for Senior
Research Fellowship [Sr. no. 2061510191, Ref. no. 21/06/2015 (I) EU-V, dated 15/12/2015].
Sumanta Jana acknowledges UGC India for offering him Dr. D. S. Kothari Postdoctoral
Fellowship [Award letter no. F.4-2/2006 (BSR)/CH/18-19/0017]. We thank USIC, The
18

Page 19 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
University of Burdwan, West Bengal, India, for providing the single crystal X-ray
5
6
diffractometer facility.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
References
(1) L. K. Das and A. Ghosh, CrystEngComm, 2013, 15, 9444–9456.
(2) D. Nagaraju, D. G. Bhagat, R. Banerjee and U. K. Kharul, J. Mater. Chem. A, 2013, 1,
8828–8835.
(3) D. K. Maity, A. Dey, S. Ghosh, A. Halder, P. P. Ray and D. Ghoshal, Inorg. Chem., 2018,
57, 251−263.
(4) R. Haldar, S. K. Reddy, V. M. Suresh, S. Mohapatra, S. Balasubramanian and T. K. Maji,
Chem. Eur. J. 2014, 20, 4347– 4356.
(5) H. Furukawa, K. E. Cordova, M. O′Keeffe and O. M. Yaghi, Science, 2013, 341,
1230444.
(6) Y. He, B. Li, M. O′Keeffe and B. Chen, Chem. Soc. Rev., 2014, 43, 5618–5656.
(7) C. Janiak and J. K. Vieth, New J. Chem., 2010, 34, 2366–2388.
(8) Y. Yang, F. Wang, Q. Yang, Y. Hu, H. Yan, Y.-Z. Chen, H. Liu, G. Zhang, J. Lu, H.-L.
Jiang and H. Xu, ACS Appl. Mater. Interfaces, 2014, 6, 18163−18171.
(9) B. Gole, U. Sanyal and P. S. Mukherjee, Chem. Commun., 2015, 51, 4872–4875.
(10) L.-W. Zeng, K.-Q. Hu, L. Mei, F.-Z. Li, Z.-W. Huang, S.-W. An, Z.-F. Chai and W.-Q.
Shi, Inorg. Chem., 2019, 58, 14075−14084.
(11) H. Li, Y. Wang, Y. He, Z. Xu, X. Zhao and Y. Han, New J. Chem., 2017, 41, 1046-
1056.
(12) K. M. L. Taylor-Pashow, J. D. Rocca, Z. Xie, S. Tran and W. Lin, J. Am. Chem. Soc.,
2009, 131, 14261–14263.
(13) H. Kitagawa, Nature Chemistry, 2009, 1, 689–690.
19

New Journal of Chemistry
Page 20 of 25
1
2
3
4
(14) M. Inukai, S. Horike, T. Itakura, R. Shinozaki, N. Ogiwara, D. Umeyama, S. NagaVrikewaArr,ticle Online
DOI: 10.1039/D0NJ03325A
5
6
7
Y. Nishiyama, M. Malon, A. Hayashi, T. Ohhara, R. Kiyanagi and S. Kitagawa, J. Am.
Chem. Soc., 2016, 138, 8505−8511.
8
9
(15) S. Ghosh, Y. Ida, T. Ishida and A. Ghosh, Cryst. Growth Des., 2014, 14, 2588−2598.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(16) P. Ghorai, A. Dey, P. Brandão, J. Ortega-Castro, A. Bauza, A. Frontera, P. P. Ray and A.
Saha, Dalton Trans., 2017, 46, 13531–13543.
(17) R. Matsuoka, R. Toyoda, R. Sakamoto, M. Tsuchiya, K. Hoshiko, T. Nagayama, Y.
Nonoguchi, K. Sugimoto, E. Nishibori, T. Kawai and H. Nishihara, Chem. Sci., 2015, 6,
2853–2858.
(18) P. Kar, R. Haldar, C. J. Gómez-García and A. Ghosh, Inorg. Chem., 2012, 51,
4265−4273.
(19) L. K. Das, C. Diaz and A. Ghosh, Cryst. Growth Des., 2015, 15, 3939−3949.
(20) S. Ganguly, P. Kar, M. Chakraborty and A. Ghosh, New J. Chem., 2018, 42,
9517−39529.
(21) L. K. Das, C. J. Gómez-García and A. Ghosh, Dalton Trans., 2015, 44, 1292–1302.
(22) I.-H. Park, R. Medishetty, J.-Y. Kim, S. S. Lee and J. J. Vittal, Angew. Chem. Int. Ed.,
2014, 53, 5591–5595.
(23) S. Jana and S. Chattopadhyay, Polyhedron, 2014, 81, 298–307.
(24) Q. Zha, X. Rui, T. Wei and Y. Xie, CrystEngComm, 2014, 16, 7371–7384.
(25) S. Ghosh, G. Aromí, P. Gamez and A. Ghosh, Eur. J. Inorg. Chem., 2015, 3028–3037.
(26) R. Haldar and T. K. Maji, CrystEngComm, 2013, 15, 9276–9295.
(27) N. Stock and S. Biswas, Chem. Rev., 2012, 112, 933–969.
(28) S. Khan, S. Halder, P. P. Ray, S. Herrero, R. González-Prieto, M. G. B. Drew and S.
Chattopadhyay, Cryst. Growth Des., 2018, 18, 651–659.
(29) L. Sun, M. G. Campbell and M. Dincă, Angew. Chem. Int. Ed., 2016, 55, 3566–3579.
20

Page 21 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
(30) R. Kaur, K.-H. Kim, A. K. Paul and A. Deep, J. Mater. Chem. A, 2016, 4, 3991–4002.
5
6
7
8
(31) K. Naskar, A. Dey, B. Dutta, F. Ahmed, C. Sen, M. H. Mir, P. P. Roy and C. Sinha,
Cryst. Growth Des., 2017, 17, 3267−3276.
9
(32) C. A. Kent, D. Liu, T. J. Meyer and W. Lin, J. Am. Chem. Soc., 2012, 134, 3991−3994.
(33) A. Dey, S. Middya, R. Jana, M. Das, J. Datta, A. Layek and P. P. Ray, J. Mater. Sci.:
Mater. Electron., 2016, 27, 6325−6335.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(34) J. Zhu, W. A. Maza and A. J. Morris, J. Photochem. Photobiol., 2017, 344, 64−77.
(35) S. Roy, A. Dey, P. P. Ray, J. Ortega-Castro, A. Frontera and S. Chattopadhyay, Chem.
Commun., 2015, 51, 12974−12976.
(36) B. Dutta, R. Jana, A. K. Bhanja, P. P. Ray, C. Sinha and M. H. Mir, Inorg. Chem., 2019,
58, 2686−2694.
(37) S. Dutta, S. Chakraborty, M. G. B. Drew, A. Frontera and A. Ghosh, Cryst. Growth
Des., 2019, 19, 5819−5828.
(38) T. K. Ghosh, P. Mahapatra, S. Jana and A. Ghosh, CrystEngComm, 2019, 21, 4620–
4631.
(39) T. K. Ghosh, S. Jana and A. Ghosh, Inorg. Chem., 2018, 57, 15216−15228.
(40) G. M. Sheldrick, Acta Cryst., 2015, C71, 3−8.
(41) O.V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard and H. Puschmann,
Olex2: A complete structure solution, refinement and analysis program, J. Appl. Cryst., 42,
2009, 339-341.
(42) SAINT and SADABS, version 6.02 and version 2.03; Bruker AXS, Inc.: Madison, WI,
2002.
(43) T. K. Ghosh, P. Mahapatra, M. G. B. Drew, A. Franconetti, A. Frontera and A. Ghosh,
Chem. Eur. J., 2020, 26, 1612−1623.
(44) A. Das, S. Jana and A. Ghosh, Cryst. Growth Des., 2018, 18, 2335−2348.
(45) C. C. R. Sutton, G. D. Silva and G. V. Franks, Chem. Eur. J., 2015, 21, 6801–6805.
(46) B. Naskar, R. Modak, D. K. Maiti, M. G. B. Drew, A. Bauza, A. Frontera, C. Das
Mukhopadhyay, S. Mishra, K. D. Saha and S. Goswami, Dalton Trans. , 2017 46,
9498−9510.
(47) J. Chakraborty, S. Thakurta, B. Samanta, A. Ray, G. Pilet, S. R. Batten, P. Jensen and S.
Mitra, Polyhedron, 2007, 26, 5139−5149.
(48) K. W. Liu, R. Chen, G. Z. Xing, T. Wu and H. D. Sun, Appl. Phys. Lett., 2010, 96,
023111.
21

New Journal of Chemistry
Page 22 of 25
1
2
3
4
(49) S. Jana, B. C. Mitra, P. Bera, M. Sikdar and A. Mondal, J. Alloy. Compd., 2014, V6ie0w2Ar,ticle Online
DOI: 10.1039/D0NJ03325A
5
6
42–48.
(50) B. Dutta, A. Dey, K. Naskar, S. Maity, F. Ahmed, S. Islam, C. Sinha, P. Ghosh, P. P.
Ray and M. H. Mir, New J. Chem., 2018, 42, 10309−10316.
(51) B. Dutta, R. Jana, C. Sinha, P. P. Ray and M. H. Mir, Inorg. Chem. Front., 2018, 5,
1998−2005.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(52) S. Roy, S. Halder, M. G. B. Drew, P. P. Ray and S. Chattopadhyay, New J. Chem., 2018,
42, 6062−6076.
(53) I. Stassen, N. Burtch, A. Talin, P. Falcaro, M. Allendorf and R. Ameloot, Chem. Soc.
Rev., 2017, 46, 3185−3241.
(54) E. H. Rhoderick and R. H. Williams, Metal–Semiconductor Contacts, Clarendon Press,
Oxford, 2nd edn, 1988.
(55) S. K. Cheung and N. W. Cheung, Appl. Phys. Lett., 1986, 49, 85−87.
(56) R. K. Gupta and F. Yakuphanoglu, Sol. Energy, 2012, 86, 1539−1545.
(57) İ. Taşçıoğlu, U. Aydemir and Ş. Altındal, J. Appl. Phys., 2010, 108, 064506.
(58) Y. S. Ocak, M. Kulakci, T. Kılıçoğlu, R. Turan and K. Akkılıç, Synth Met., 2009,
159,1603–1607.
(59) R. Şahingöz, H. Kanbur, M. Voigt and C. Soykan, Synth Met., 2008, 158, 727–731.
(60) A. Jain, P. Kumar, S. C. Jain, V. Kumar, R. Kaur and R. M. Mehra, J. Appl. Phys., 2007,
102, 094505.
(61) Ş. Aydoğan, M. Sağlam and A. Türüt, J. Phys. Condens. Mater 2006, 18, 2665–2676.
(62) P. W. M. Blom, M. J. M. d. Jong and M. G. v. Munster, Phys. Rev. B, 1997, 55, R656–
R659.
(63) A. K. Bhanja, S. Mishra, K. Naskar, S. Maity, K. Das Saha and S. Sinha, Dalton Trans.,
2017, 46, 16516−16524.
(64) S. Middya, A. Layek, A. Dey, J. Datta, M. Das, C. Banerjee and P. P. Ray,
ChemPhysLett., 2014, 610-611, 39–44.
(65) M. Das, J. Datta, A. Dey, R. Jana, A. Layek, S. Middya and P. P. Ray, RSC Adv., 2015,
5, 101582–101592.
(66) S. Halder, M. Das, K. Ghosh, A. Dey, B. B. Show, P. P. Ray, and P. Roy, J. Mater.
Sci., 2016, 51, 9394–9403.
22

Page 23 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
Table 1: Crystal data and structure refinement of complexes 1 and 2.
5
6
7
Complex
1
2
8
9
C42 H54 Cd4 N14 O16 C28.5 H29 Cd2 N3 O8.5
Chemical formula
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Formula weight
Crystal system
Space group
1460.63
Orthorhombic
Pbca
774.35
Triclinic
a(Å)
b (Å)
c (Å)
α(ᵒ)
12.4732(5)
10.570(2)
17.255(4)
17.545(4)
72.062(3)
72.882(3)
72.850(3)
2835.2(11)
4
17.7256(7)
23.1634(10)
90
β (ᵒ)
90
γ(ᵒ)
90
5121.3(4)
4
V (Å)3
Z
ρcalc(g cm-3)
1.894
300
1.721
2896
0.028
111500
5264
1.814
296
T (K)
µ (Mo Kα) (mm-1)
1.558
1540
0.039
20921
10704
8103
F(000)
R(int)
Total reflections
Unique reflections
Reflections with I >
2σ(I)
4716
a
b
[I>2σ(I)]R1 , wR2
0.0293,0.0765
0.0396,0.1211
R(all data)
GOFc on F2
0.0355
1.289
-0.63,0.57
0.0566
1.011
-0.82,0.68
Residual electron
Density, e/Å-3
2
2
4 ½
2
½
aR1 = ||Fo|−|Fc|||Fo|,bwR2 (Fo ) = [[w(Fo − Fc2)2w Fo ] and cGOF = [[w(Fo − Fc2)2(Nobs– Nparams)]
23

New Journal of Chemistry
Page 24 of 25
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
Table 2: Photosensitivity of complexes 1 and 2 obtained from I-V curve.
5
6
7
8
Complex
Condition
Leakage current
Ratio
Photosensitivity
Reverse
Forward
3.46×10-8 8.4×10-8
5.39×10-8 1.48×10-7
3.42×10-4 8.13×10-4
1.16×10-4 1.49×10-3
IPh/ID
1
1
2
2
dark
light
dark
light
2.42
2.74
1.13
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
2.37
5.41
12.84
Table 3: Device parameters for complex 1.
Condition
On/off
conductivity
ideality
factor
η
dv/dlnI
Rs
H
barrier
δ
Rs
height
ΦB
dark
light
2.34
2.89
13.1×10-8
11.2×10-7
2.58
7
8.7
0.67
0.41
1.46
2.58
3.46
Table 4: Device parameter for complex 2.
Condition on
/off
conductivity δ ideality dv/dl
H
barrier
life
D
LD
mobility
µeff
factor
nI
Rs
height time ×10- ×10-
11
5
η
Rs
ΦB
t
×10-8
(s)
dark
light
2.3
13
5.4×10-8
2.5
25.26 24.37
8.21 7.48
0.63
0.32
1.96 292.6 3.38
1.31 49.8 1.14
8.78
13.5×10-7
1.24
1.495
24

Page 25 of 25
New Journal of Chemistry
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03325A
Table of Contents Only
5
6
7
8
9
Tetra- and poly-nuclear Cd(II) complexes of an N3O4 Schiff base
ligand: Crystal structures, electrical conductivity and
photoswitching property
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Tanmoy Kumar Ghosh,a Sumanta Jana,b Subrata Janaa and Ashutosh Ghosha*
A tetranuclear and a polymeric Cd(II) complex have been synthesized and charecterized. The
polymeric complex based device behaves as Schottky Barrier Diode and exhibits
photoswitching property.