Synthesis and optical properties of copper(II) and nickel(II) complexes of a highly fluorescent morpholine-derivative

Article abstract of DOI:10.1016/j.poly.2019.07.044

A morpholine substituted methyl 3-hydroxy-2-naphthoate was synthesized. The morpholine derivative displayed an intense fluorescence. Owing to the presence of suitable donor atoms, it was employed for the detection of transition metal ions. The crystals of copper and nickel complexes of the fluorescence active ligand were grown via vapor diffusion method. The ligand structure and its metal complexes were characterized using ¹H NMR, IR, HR-MS and single crystal X-ray crystallography. The synthesized ligand displayed selective turn-off fluorescence response in the presence of Cu²⁺ and Ni²⁺ ions. Fluorescence active letters were encoded successfully on filter paper utilizing metal complexes as a tool towards digital writing.

Full text of DOI:10.1016/j.poly.2019.07.044

Polyhedron 171 (2019) 559–570
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis and optical properties of copper(II) and nickel(II) complexes of
a highly fluorescent morpholine-derivative
⇑
Priya Ranjan Sahoo, Arvind Kumar, Ajeet Kumar, Satish Kumar
Department of Chemistry, St. Stephen’s College, University Enclave, Delhi 110007, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A morpholine substituted methyl 3-hydroxy-2-naphthoate was synthesized. The morpholine derivative
displayed an intense fluorescence. Owing to the presence of suitable donor atoms, it was employed for
the detection of transition metal ions. The crystals of copper and nickel complexes of the fluorescence
active ligand were grown via vapor diffusion method. The ligand structure and its metal complexes were
characterized using 1H NMR, IR, HR-MS and single crystal X-ray crystallography. The synthesized ligand
displayed selective turn-off fluorescence response in the presence of Cu and Ni ions. Fluorescence
active letters were encoded successfully on filter paper utilizing metal complexes as a tool towards digital
writing.
Received 5 May 2019
Accepted 30 July 2019
Available online 9 August 2019
Keywords:
Crystal structure
Cu complex
Ni complex
Fluorescent complexes
Digital writing
2+
2+
Ó 2019 Elsevier Ltd. All rights reserved.
1
. Introduction
Heterocyclic ligands with metal-coordinating sites along with
multidirectional growth pattern. Metal complex self-assembled
structures are potentially useful in the diverse fields of molecular
machines, optoelectronics, semiconductor devices for energy stor-
age etc. [16–18]. Transition metal complexes can also exhibit
accessible oxidation and reduction pathways, which helps in accel-
erating electronic performance [19,20]. Metal complexes with
transition metal ion at its central core are also used as molecular
magnets [21–23]. The wide applicability of the transition metal
complexes in such applications lies in their tendency to flexibly
tune intermolecular interactions through ligand modification,
which modify their properties to obtain desired results. In this con-
text, small molecule organic linkers are receiving increasing atten-
tion in recent times owing to their easy availability, remarkable
host–guest response and flexible tendency in achieving
supramolecular architecture [24]. In addition, metal–organic com-
plexes can also showcase special geometry and size along with an
interesting optical response [25,26]. The development of
supramolecular architectures capable of color as well as fluores-
cence changes upon complexation and solid state fabrication is
also of great interest, which can be utilized for on-site and real-
time detection of toxic metal ions [27]. Such novel optical detec-
tion tools with flexible binding sites, superior signal, and portable
features can be of great interest in the area of environmental
science [28,29]. Among various utility of transition metal ion com-
plexes, the copper complexes often play a central role in biochem-
ical and enzymatic processes [30,31]. Copper is also an important
cation in biochemistry, neurobiology and plays a significant role
in enzymatic transformation reactions [32]. The strong ligand
binding response of copper and its inherent redox nature imply a
self-complementary hydrogen bonding sites facilitate supramolec-
ular assembly and directional growth [1,2]. The metal complexes
are centre of attention during last several decades for producing
network structures with desired properties through self assemblies
directed by different metal ions [3–5]. Numerous examples are
available in the literature, where heterocyclic ligands having mor-
pholine acts as a coordinating moiety for binding transition metal
ions [2,6]. A number of examples are also available in the literature,
where heterocyclic molecules along with carboxylate and –OH
groups are used for MOFs construction owing to the availability
of variable modes of coordination [2,7–9]. Mono and di-carboxy-
lated groups are often useful as they can show a flexible binding
mode, and offer interesting multimodal coordination environ-
ments for metal ions such as octahedral, tetrahedral or square pla-
nar [10]. Heterocyclic molecules are often used for the detection of
metal ions owing to their affinity towards metal ions [11] and dis-
play an optical response, which may be in the form of a color or
change in fluorescence signal [3–5]. In addition, a complex struc-
ture formed through the association of metal ion with a hetero-
cyclic ligand may often display porous nature for binding gas
molecules or ion binding and can also be used in catalysis
[
12–15]. The metal–ligand complex in some cases forms a
unidirectional assembly, while in other cases they may display a
⇑
Corresponding author.
E-mail address: satish@ststephens.edu (S. Kumar).
https://doi.org/10.1016/j.poly.2019.07.044
277-5387/Ó 2019 Elsevier Ltd. All rights reserved.
0

5
60
P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
diverse role in dioxygen transport, energy production and signal
transduction [33]. Imbalance in copper ion uptake during life pro-
cesses can lead to Menkes and Wilson’s disease [34]. Therefore,
development of robust and versatile ligands is the prerequisite
for monitoring and efficient removal of excess Cu2 ions.
Besides copper ion, nickel ion is an important element for cellu-
lar organisms and metalloenzymes. Nickel ion containing com-
plexes having nitrogen and oxygen atoms are found in active
sites of many enzymes such as hydrogenases and carbon monoxide
dehydrogenases [35,36]. Apart from its biological role, carboxylate
based nickel complexes are often used as potential candidates as
adsorption agents, catalysts, and molecular magnets [37].
2.2.3. Synthesis of 1–Cu complex
The ligand 1 (0.5 g, 1.66 mmol) and copper acetate (0.33 g,
1.65 mmol) were dissolved separately in 10 mL acetonitrile and
mixed in a 50 mL round bottom flask. Then the solution was stirred
for 2 h. It was filtered out and the solvent was evaporated under
reduced pressure. The crude product was dissolved in a small
amount of acetonitrile, which was subjected to vapor diffusion of
diethyl ether and kept inside the refrigerator. Blue colored crystals
+
were observed after one week. Yield: 42% m.pt. 182–187 °C. IR
À1
(KBr,
m
-cm ): 3468, 2952, 1644, 1456, 1322, 1212, 1114, 792,
+
666. HRMS C35
789.6478.
2
H36Cu N
2
O
2
10ÁH O calculated 789.75 found [M] :
In the present work, we have synthesized a fluorescent ligand,
2
+
2+
its Cu
and Ni
complexes by utilizing easily available 3-
2
.2.4. Synthesis of 1–Ni complex
The ligand 1 (0.5 g, 1.66 mmol) and nickel acetate (0.41 g,
.64 mmol) were dissolved separately in 10 mL acetonitrile and
hydroxy-2-naphthoic acid and morpholine precursors. The two
steps synthetic process involves methylation of 3-hydroxy 2-naph-
thoic acid followed by Mannich condensation in benzene to yield 1.
The morpholine moiety was anchored to the hydroxy naphthoate
system in order to achieve flexible functions such as chelation
and color generation.
1
mixed in a 50 mL round bottom flask. Then the solution was stirred
for 2 h. It was filtered out and the solvent was evaporated under
reduced pressure. The crude product was dissolved in a small
amount of acetonitrile, which was subjected to vapor diffusion of
diethyl ether and kept inside the refrigerator. Green crystals were
observed after two weeks. Yield: 34% m.pt. 152–158 °C. IR (KBr,
2
. Experimental
À1
m-cm ): 3456, 3252, 2958, 1686, 1594, 1440, 1320, 1212, 1114,
8
66, 792, 684. HRMS C44
H
55
N
2
Ni
4
O
22ÁC
2
H
4
O
2
Á2(H
2
2 3
O)Á5(C H N) cal-
2.1. Material and methods
+
culated m/z: 1322.1505; found [M+H] : 1323.8843.
All reagents and solvents for synthesis purposes were pur-
chased commercially and were utilized as received. H NMR and
C NMR spectra were recorded on 400 MHz Joel NMR ECX 400
1
2.3. NMR studies
1
3
1
The H NMR spectra of the ligand 1 and its complex with copper
NMR spectrometer. Mass measurements were performed using
an Agilent 6500 Series Accurate Mass Q-TOF Spectrophotometer.
IR measurements were performed using a Bruker FT-IR Spec-
trophotometer using a KBr pellet. X-ray diffraction was carried
out on an Oxford XcaliburS diffractometer. Differential Thermal
Analysis and Thermo Gravimetric Analysis were recorded on Per-
kin Elmer, Pyris diamond TGA/DTA instrument. PXRD spectra were
recorded on Bruker, Rigaku, High-Resolution X-ray diffractometer.
UV–Vis spectra were recorded on Ocean Optics USB 4000 UV–Vis
Spectrometer. Fluorescence measurements were performed using
a Cary Eclipse fluorescence spectrophotometer.
or and nickel ions were recorded on a 400 MHz instrument in
3
CDCl . Solutions were prepared by dissolving 3 mg 1–Ni or 1–Cu
complex in 0.7 mL CDCl
3
.
2.4. Crystallography
Single crystals of 1, 1–Cu and 1–Ni suitable of X-ray diffraction
were mounted on an Xcalibur Sapphire 3 diffractometer. The crys-
tal data for 1, 1–Cu and 1–Ni were collected at 297 K. The detailed
crystal data, collection and structure refinement parameters for 1
are given in Table 1. OLEX2 [38] GUI was employed to get the solu-
tion of the structure with the help of SHELXT/direct method [39] and
refinement was accomplished using SHELXL/least square program
2
2
.2. Synthesis
[
39]. All the non-hydrogen atoms in all the structures were refined
anisotropically. The hydrogen atoms present in CAH (aromatic),
ACH and ACH groups of different crystal structures reported in
this paper were placed at their appropriately calculated positions
CAH = 0.93 Å, ACH = 0.97 Å, ACH = 0.96 Å and treated with a
riding model such that Uiso (H 4CAH and ACH ) = 1.2Ueq(C), Uiso
H 4-CH ) = 1.5Ueq(C). The ACH groups were treated as ideal
.2.1. Synthesis of 1 [methyl 3-hydroxy-4-(morpholinomethyl)-2-
naphthoate]
In a 100 mL round bottom flask, methyl 3-hydroxy-2-naph-
thoate (1.0 g, 4.94 mmol) was mixed with paraformaldehyde
0.3 g, 9.9 mmol) and morpholine (0.7 mL, 8.11 mmol) and was
refluxed in 15 mL of benzene for 24 h. The resulting reaction mix-
ture was filtered and yellow crystals were formed after 1 h. Yield:
2
3
(
2
3
(
2
(
3
3
rotary groups during refinement. The NAH and OAH atoms in all
the structures were refined freely. Mercury software [40] was used
to prepare the graphics material for publication.
À1
(
2
(
7
1.38 g) 93%. M.pt. 118–123 °C. IR (KBr,
m
-cm ): 3432, 3230, 2949,
1
806, 2847, 2768, 1686, 1440, 1304, 1169, 1113, 1091. H NMR
400 MHz, DMSO-d , d): 8.46 (s, 1H), 8.07 (d, 1H, J = 8.4 MHz),
.95 (d, 1H, J = 8.4 MHz), 7.61–7.57 (t, 1H), 7.39–7.35 (t, 1H), 3.95
6
13
(
brs, 9H, CH
d): 169.2, 153.9, 136.2, 132.0, 129.8, 129.0, 126.6, 123.7, 123.6,
15.9, 115.0, 66.2, 53.0, 52.8, 52.0. HRMS (m/z) calculated for
2
, CH
3
) 3.52 (4H, CH
2
). C NMR (100 MHz, DMSO-d
6
,
3. Results and discussion
1
[
3.1. Synthesis
+
17 4
C H19NO +H]: 302.1314 found [M+H] 302.1386.
The ligand 1 was synthesized as per Scheme 1 that involved a
reaction between 3-hydroxy-2-naphthoic acid and methanol in
the presence of catalytic amount of sulfuric acid followed by a
Mannich reaction to yield 1 in good yield. The ligand 1 was charac-
terized spectroscopically and single crystal X-ray crystallography.
The ligand 1 was treated with copper and nickel acetate in
acetonitrile to yield single crystals, which were also analyzed
2
.2.2. Preparation of metal complexes
Suitable crystals of copper and nickel bound complexes were
grown through vapor diffusion method. However, multiple efforts
in crystallizing other metal ion (such as Mn , Fe , Co , Cd , Zn
Pb , Hg ) complexes were remain unsuccessful.
2+
3+
2+
2+
2+
,
2
+
2+

P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
561
Table 1
The crystal data, collection and refinement indicators for 1, 1–Cu and 1–Ni.
(
1)
1858233
19NO
(1–Cu)
(1–Ni)
CCDC
1858234
1858235
Chemical formula
C
17
H
4
C
35
H36Cu
2
N
2
O
10ÁH
2
O
C
44
H
59
N
Ni
2 4
O
22ÁC
2
H
H N)
2 4
3
O
2
Á2(H O)Á1.39
2
(
C
2
H
3
N)Á0.49(C
M
r
301.33
orthorhombic, Pbcn
297
789.75
triclinic, P1
297
1379.25
monoclinic, P2
297
Crystal system, space group
T (K)
1
/c
a, b, c (Å)
13.4337 (9), 11.3288 (7), 20.0878 (11)
11.1116 (3), 12.6329 (4), 14.3075 (5)
14.9290 (5), 12.5856 (4), 33.1848 (15)
a
, b,
c
(°)
90, 90, 90
3057.1 (3)
8
94.219 (3), 112.216 (3), 113.670 (3)
1641.63 (9)
2
90, 92.621 (3), 90
6228.6 (4)
4
3
V (Å )
Z
Radiation type
Mo K
0.09
a
Mo K
1.36
a
Mo K
1.27
a
À1
m (mm
)
Crystal size (mm)
Data collection
0.1 Â 0.1 Â 0.04
0.02 Â 0.02 Â 0.01
0.02 Â 0.04 Â 0.03
Diffractometer
Xcalibur, Sapphire3
Xcalibur, Sapphire3
Xcalibur, Sapphire3
Absorption correction
Multi-scan CrysAlis PRO (Agilent, 2013) Multi-scan CrysAlis PRO (Agilent, 2013) Multi-scan CrysAlis PRO (Agilent, 2013)
Tminimum, Tmaximum
0.678, 1.000
0.934, 1.000
0.830, 1.000
Number of measured, independent
24 563, 3850, 3150
20 171, 6103, 5143
46 438, 11571, 8841
and observed [I > 2r(I)] reflections
R
int
0.028
0.690
0.034
0.606
0.055
0.606
À1
(
sin h/k)maximum (Å
)
Refinement
2
2
2
R[F > 2
r
(F )], wR(F ), S
0.071, 0.155, 1.16
0.036, 0.085, 1.02
0.054, 0.126, 1.04
Number of parameters
Number of restraints
H-atom treatment
204
0
459
0
767
3
H atoms treated by a mixture of
independent and constrained
refinement
0.24, À0.17
H atoms treated by a mixture of
independent and constrained
refinement
0.31, À0.29
H atoms treated by a mixture of
independent and constrained
refinement
1.40, À0.55
À3
D
q
maximum
,
D
q
minimum (e Å
)
Scheme 1. The synthetic route for the preparation of 1.
spectroscopically and through single crystal X-ray crystallography
Figs. S1–S9).
units were observed to be interconnected to each other through
intermolecular short contacts (Table 2).
(
3.2. Crystal structure of 1
3.3. Structure of the 1–Cu complex
The crystals suitable for X-ray diffraction were grown through
slow evaporation of a solution of 1 in benzene. The crystal param-
eters are listed in Table 1. The asymmetric unit displayed a single
The crystals of the 1–Cu complex were grown from a solution of
acetonitrile:ether (1/1) and the crystal data along with recording
parameters are given in Table 1. The asymmetric unit consisted
of two Cu ions, two hydroxy naphthoate ligands, one acetate unit
and one water molecule in the asymmetric unit (Fig. 3). The five
2
+
molecule of the ligand
intramolecular interactions in the crystal structure were examined
Table 2). An intramolecular H-bond interaction between
1
(Fig. 1). The intermolecular and
2
+
(
coordinated Cu
ions exhibited square pyramidal geometry
2
+
O1AH1Á Á ÁO2 (Table 2) was observed in the asymmetric unit. The
C7AC18AN5 angle was observed to be 113.24(15). The torsion
angle (O4AN5AC7AC14) between the morpholine unit and the
naphthyl unit was observed to be 59.4(3)°. Morpholine was
observed to be present in the chair configuration. The crystal pack-
ing in 1 displayed several short CAHÁ Á ÁO and CAHÁ Á ÁN type inter-
actions (Table 1, Fig. 1).
The crystal packing shown in Fig. 2(a) display the molecular
units placed opposite to each other in an anti-parallel fashion.
However, in Fig. 2(b), naphthyl subunits were situated facing par-
allel to each other with perfection.
(Fig. 3). One of the Cu ion coordinated by two oxygen atoms from
hydroxy naphthoate ligands (Cu1AO5, 1.975(2) Å, Cu1AO4, 1.932
(2) Å), one nitrogen atom from morpholine unit (Cu1AN15, 2.040
(2) Å), one oxygen from the second naphthoxide unit (Cu1AO3,
1.969(2) Å) and an acetate unit (Cu1AO8, 2.206(2) Å). The other
Cu ion linked by two oxygen atoms from hydroxy naphthoate
ligands (Cu2AO6, 1.898(2) Å, Cu2AO3, and 1.954(2) Å), other
nitrogen atom from the other morpholine unit (Cu2AN14, 2.084
(2) Å), one oxygen from the first naphthoxide unit (Cu2AO4,
2
+
2
+
2.575(2) Å). The two Cu ions were found to be connected by
the naphthoxide oxygen atoms in parallelogram geometry. The
morpholine units retained their chair configuration in the complex.
The mean plane of the two naphthyl units (atoms were coplanar
within 0.03 Å and 0.04 Å) displayed 50.41(7)° angle with respect
to each other. The asymmetric unit displayed an H-bond between
The crystallographic molecular units inside the lattice were
linked through intermolecular short contacts that were found to
be arranged in such a way that the molecular units in 1 seem to
be stacked (Fig. 2, Table 2). Interestingly, all the four molecular

5
62
P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
O10Á Á ÁO13 and H13BAO19 atoms (Table 3). The CuACu distance
was observed 2.9764(4) Å to be considerably shorter than the
CuACu distance reported in the literature [41]. The asymmetric
unit also displayed two weak CAHÁ Á ÁO (C47AH47BÁ Á ÁO75 and
C31AH31BÁ Á ÁO5) short contacts (Table 3). The crystal packing of
the 1–Cu complex revealed several intramolecular CAHÁ Á ÁO type
short contacts (Table 3). The water molecule present in the crystal
structure holds the different moieties of the complex together in
the crystal lattice through H-bonds (Fig. S10).
3.4. Structure of the 1–Ni complex
The crystals of the 1–nickel complex were grown through slow
evaporation of a solution of the ligand 1 and excess of nickel acet-
ate in acetonitrile:diethyl ether (1:1) solution. The green color
crystals of the complex were obtained as monoclinic crystal in
1
the P2 c space group. The important crystal data and other
recording and refinement parameters are listed in Table 1. The
crystal structure of the 1–Ni complex consisted of four Ni2+ ions,
two naphthoate units, two acetonitrile, four water molecules and
six acetate units (Fig. 4). Overall, a 1:2 (ligand to metal) stoi-
chiometry was observed. The four nickel atoms were present in
an octahedral arrangement connected to six different atoms in
the complex. Two acetate molecules act as a bridge between four
nickel atoms, At least one oxygen atom (O14 and O15) of both
acetate fragments coordinate to at least two nickel atoms. Two
acetate fragments were observed to be coordinated to the nickel
atoms present on the periphery of the complex. Each ligand unit
is coordinated to two nickel atoms through the nitrogen atom of
the morpholine unit, phenolic oxygen atom and the carbonyl
group of the ester. The two oxygen atoms emanating from pheno-
lic unit (O5 and O9) and two oxygen atoms (O26 and O27) of the
two water molecules coordinated with two nickel atoms. One
acetic acid molecule, two water molecules are coordinated to
the complex through H-bonds (Table 4). Considerably shorter
NiANi metal distances were observed in the crystal structure
(Ni1ANi2: 3.1018(7) Å, Ni2ANi3: 3.0692(7) Å, Ni3ANi4: 3.0916
Fig. 1. ORTEP view of 1 with displacement ellipsoids at the 50% probability level. An
intramolecular H-bonding of 2.625 Å observed between O AO .
2 1
Table 2
Hydrogen-bond geometry (Å, °) for 1.
(
8) Å. In addition, the fragments present in the asymmetric unit
displayed a number of H-bond and weak CAHÁ Á ÁO short contacts
Fig. 4, Table 4). For example, the acetonitrile molecule was linked
DAHÁ Á ÁA
DAH
HÁ Á ÁA
DÁ Á ÁA
DAHÁ Á ÁA
(
O1AH1Á Á ÁO2
0.89 (3)
0.93
0.96
0.97
0.97
1.80(3)
2.84
2.49
2.36
2.65
2.625(2)
3.344(3)
3.303(3)
2.783(3)
3.510(3)
3.243(3)
152(3)
115.2
142.6
105.4
148.1
103.8
C9AH9Á Á ÁN5
to the complex through CAHÁ Á ÁO and CAHÁ Á ÁN short contacts,
while an acetic acid molecule linked to the complex through mul-
tiple OAHÁ Á ÁO, H-bonds (Table 4). The crystal packing also dis-
plays a number of weak CAHÁ Á ÁO and intermolecular H-bond
interactions (Table 4, Fig. S11). An acetonitrile molecule present
in the crystal structure was disordered.
i
C17AH17BÁ Á ÁO4
C18AH18BÁ Á ÁO1
ii
C20AH20AÁ Á ÁO1
C22AH22AÁ Á ÁO1
0.97
2.87
Symmetry codes: (i) x + 1/2, y + 1/2, Àz + 3/2; (ii) Àx + 3/2, y À 1/2, z.
Fig. 2. Crystal packing diagram of 1 viewed (a) along axis b and (b) along axis c showing intermolecular short contacts. Ellipsoids are shown at 50% probability level.

P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
563
molecular interactions via red, blue and white color chart. The red
color displays contacts shorter than Van der Waal’s radii, blue color
describe the contacts, which are longer than Van der Waal’s radii
while white colored area denotes contacts of the order of Van
der Waal’s radii. The asymmetric unit observed in the crystal struc-
ture of 1 and its copper and nickel complexes were used to calcu-
late the Hirshfeld surfaces (Fig. 5). The big red circle in the
Hirshfeld surface of 1 indicated CAHÁ Á ÁO type strong intermolecu-
lar contacts (Fig. S12), while OAHÁ Á ÁO, CAHÁ Á Á
interactions are depicted by red spots in 1–Cu (Fig. S13) and 1–Ni
Fig. S14).
The Crystal Explorer program was further used to investigate
p
and CAHÁ Á ÁO type
(
the intermolecular interactions quantitatively through the 2D-
Fingerprint plots. The complete 2D fingerprint plots for 1 and its
complex is shown in Fig. 6, which indicates a significant difference
(Fig. 6). The contributions of different type of short contacts in the
Hirshfeld surface area are given in the Table S1 and Fig. 7. The con-
tribution of the HAH interactions to the total Hirshfeld surface area
is highest for 1, 1–Cu and 1–Ni (Fig. S15, Table S1). However, the
HÁ Á ÁH interactions contribute less to the total Hirshfeld surface in
Fig. 3. ORTEP view of 1–Cu complex with displacement ellipsoids at the 30%
probability level.
1
–Cu (51.6%) in comparison to the contribution of the HÁ Á ÁH inter-
actions to the total Hirshfeld surface in 1 (58.3%). The HÁ Á ÁH inter-
actions contribute more to the total Hirshfeld surface area in 1–Ni
Table 3
(
62.1%) in comparison to 1, which may be attributed to the OÁ Á ÁH
Hydrogen-bond geometry (Å, °) for 1–Cu.
interactions. The CÁ Á ÁH (Fig. S16) and OAH (Fig. S17) interactions
also contribute significantly in 1, 1–Cu and 1–Ni (Table S1,
Fig. 7). The percent contribution of CÁ Á ÁH (1: 17.8%, 1–Cu: 24.4%,
DAHÁ Á ÁA
DAH
HÁ Á ÁA
DÁ Á ÁA
DAHÁ Á ÁA
O13AH13BÁ Á ÁO10
0.81(5)
0.97
0.97
0.97
0.97
2.13(4)
2.42
2.56
2.40
2.24
2.934(3)
3.129(3)
3.161(4)
3.036(3)
2.835(3)
3.092(3)
175(5)
129.8
119.9
123.1
118.5
123.6
i
C27AH27BÁ Á ÁO11
C28AH28AÁ Á ÁO5
C31AH31BÁ Á ÁO5
C45AH45AÁ Á ÁO6
C47AH47BÁ Á ÁO7
1
–Ni: 14.7%) and OAH (1: 16.7%, 1–Cu: 20.3%, 1–Ni: 14.8%) inter-
actions in 1–Cu are found to be highest to the total Hirshfeld sur-
face in comparison to their contributions in 1 and 1–Ni. No, NÁ Á ÁH
intermolecular interactions were present in 1–Cu complex, while
NÁ Á ÁH interactions contribute 1% in 1 and 5.6% in the 1–Ni complex
to the total Hirshfeld surface (Fig. S18). No intermolecular interac-
tions of the NÁ Á ÁO type were observed in 1–Cu and 1–Ni, while
NÁ Á ÁO interactions contribute 0.1% to the total Hirshfeld surface
in 1 (Fig. S18). The CÁ Á ÁC interactions contributed 2.1%, 0.1% and
0.97
2.45
Symmetry code: (i) Àx + 1, Ày + 1, Àz + 2.
3.5. Intermolecular interaction analysis in 1, 1–Cu and 1–Ni
0
.7% to the total Hirshfeld surface in 1, 1–Cu and 1–Ni, respectively
Figs. S19 and 7, Table S1). The CÁ Á ÁO interactions contribute 3.0%,
.4% and 1.8% to the total Hirshfeld surface in 1, 1–Cu and 1–Ni,
respectively (Figs. S20, 7, Table S1). No intermolecular interactions
The intermolecular interactions in all the crystals structures
(
2
were analyzed using the Hirshfeld surface analysis [42] with the
help of Crystal Explorer software [43], which map the normalized
contact distances as dnorm. The Hirshfeld surface displays the inter-
Fig. 4. ORTEP view of 1–Ni complex with displacement ellipsoids at the 50% probability level.

5
64
P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
Table 4
Hydrogen-bond geometry (Å, °) for (1–Ni).
DAHÁ Á ÁA
O25AH25AÁ Á ÁO22
DAH
HÁ Á ÁA
2.10
DÁ Á ÁA
DAHÁ Á ÁA
i
0.87
0.87
2.755(4)
2.736(5)
2.981(4)
2.502(4)
2.776(5)
2.690(4)
2.517(4)
3.187(17)
2.899(15)
2.710(4)
3.527(6)
3.427(11)
3.000(5)
3.405(6)
3.332(6)
3.013(5)
3.212(5)
3.123(5)
3.439(10)
131.5
172.5
113(4)
170(6)
168(6)
174(5)
167(4)
158.8
166.4
168.0
177.3
142.3
115.7
143.6
145.5
119.2
154.2
119.6
148.4
O25AH25BÁ Á ÁO29
O26AH26AÁ Á ÁO19
O26AH26AÁ Á ÁO20
O26AH26BÁ Á ÁO21
O27AH27AÁ Á ÁO21
O27AH27BÁ Á ÁO24
O28AH28AÁ Á ÁN82
O28AH28AÁ Á ÁN82A
O28AH28BÁ Á ÁO22
1.87
0.90(6)
0.90(6)
0.75(6)
0.81(5)
0.98(5)
0.88
0.88
0.88
0.96
0.96
0.97
0.97
0.97
0.97
0.96
0.96
0.96
2.52(6)
1.62(6)
2.04(6)
1.88(5)
1.55(5)
2.35
2.03
1.84
2.57
2.62
2.45
2.58
2.49
2.42
2.32
2.54
2.58
ii
C44AH44AÁ Á ÁO30
C61AH61AÁ Á ÁN79
C63AH63BÁ Á ÁO23
C64AH64AÁ Á ÁO28
C65AH65BÁ Á ÁO28
C66AH66AÁ Á ÁO16
C70AH70AÁ Á ÁO10
C74AH74CÁ Á ÁO6
C81AH81CÁ Á ÁO24
Symmetry codes: (i) Àx + 1, y + 1/2, Àz + 1/2; (ii) Àx + 1, y À 1/2, Àz + 1/2.
Fig. 5. The Hirshfeld surfaces of [a] 1 and [b] 1–Cu and [c] 1–Ni complex mapped with dnorm using Crystal Explorer software [43].
Fig. 6. The complete 2D fingerprint plots of (a) 1, (b) 1–Cu complex, (c) 1–Ni complex.
of the type NÁ Á ÁN and CÁ Á ÁN were observed in 1 and 1–Cu. The
intermolecular interactions of the type NÁ Á ÁN and CÁ Á ÁN contribute
3.6. UV–Vis studies
0
.1% and 0.2%, respectively to the total Hirshfeld surface in 1–Ni
Due to the presence of coordinating sites such as AOH and
ACOOMe groups, it was anticipated that the ligand 1 may bind
to metal ions. Therefore, the ligand 1 was evaluated for affinity
towards various transition metal ions in methanol. On addition
of one equivalent solution of various transition metal ions in a
solution of 1, slight color changes from colorless to light yellow
(
Figs. S21, 7, Table S1), which may be attributed to the presence
of acetonitrile as a solvent. The intermolecular interactions of the
type MÁ Á ÁH, MÁ Á ÁO and MÁ Á ÁC were observed in 1–Cu complex
and contributes 0.2%, 0.1% and 0.1%, respectively to the total Hirsh-
feld surface (Figs. S22, 7, Table S1). However, these interactions
were absent in 1–Ni complex.
2
+
2+
were observed in case of Ni and Cu ions. However, similar color

P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
565
change was not noticed with other metal ions. The naked eye
response of the ligand 1 towards various metal ions is displayed
in Fig. S23.
Further, the UV–Vis spectra of the ligand 1 in methanol were
investigated with metal ions (Fig. 8). The free ligand 1 displayed
a broad band at 370 nm. Bathochromic shifts were observed upon
2
+
2+
addition of one equivalent Ni and Cu ions, which indicated the
2
+
2+
affinity of the ligand 1 towards Ni and Cu ions. However, no
such changes in absorption were noticed with other transition
metal ions.
The detection of Ni2+ and Cu2+ ions were performed in the pres-
ence of other metal ions, which indicated no significant interfer-
ence due to other metal ions (Figs. S24 and S25).
2
+
Upon incremental addition of Cu ions into a solution of the
ligand in methanol, a significant increase in the intensity of absorp-
tion band at 430 nm was observed with a simultaneous decrease in
the absorption band intensity at 370 nm (Fig. 9a). When the ligand
solution was titrated with a Ni ion solution, a new band at
20 nm evolved with a simultaneous reduction in the intensity of
2
+
4
Fig. 7. The contributions (%) of the different type of short intermolecular contacts to
the Hirshfeld surface area in 1, 1–Cu and 1–Ni.
the band at 370 nm (Fig. 9b). However, no such changes were
noticed with other metal ions, which indicated the selectivity of
1
towards nickel and copper ions. The titration data was analyzed
using HYPSPEC [44] program to access the strength of association
between the ligand and the metal ions (Table 5). Different complex
stoichiometry between the ligand and the metal ions were
screened for best agreement between the observed and calculated
absorbance. A 1:1 (H:L) stoichiometry yielded the best agreement
between observed and calculated absorbance data for copper ions
(Fig. S26). The 1:1 complex stoichiometry between ligand and cop-
per ion was observed in crystal structure also. However, in case of
nickel ions 1:2 (H:L) complex stoichiometry yielded best agree-
ment between observed and calculated data. The complex geome-
try obtained through the crystal structure in case of nickel complex
agreed with the solution state complex stoichiometry.
In order to further explore the utility of the ligand 1, the exper-
imental titration data was used to calculate the limit of detection
values using the 3
versus the concentration of the metal ions were drawn, which
r/m equation. The plots between the absorbance
À5
Fig. 8. Absorption spectra of 1 ([1] = 2.5 Â 10 M) with 1.0 equivalent amounts of
n+
2+
2+
2+
2+
2+
2+
2+
3+
acetate salt of various metal ions (M = Ni , Cu , Hg , Mn , Zn , Co , Ni , Cr
Fe , Cd , Pb , Ag = 2.5 Â 10 M) in MeOH. For simplicity spectra of only a few
,
yielded linear relationships. The plots yielded a value of 2.2 lM
3+
2+
2+
+
À5
2+
2+
(
Fig. S27a) for Cu and 1.3 lM for Ni as the limit of detection
important metal ions are shown.
(Fig. S27b).
Fig. 9. Changes in UV–Visible spectra of 1 ([1] = 2.5 Â 10À5 M) upon incremental addition of (a) Cu2+ (b) Ni2+ ion in MeOH.
Table 5
Calculated binding constants of ligand 1 from UV–Vis titration using HYPSPEC [44].
Zn2+
Ni2+
Cu2+
Mn2+
Cd2+
Co2+
Hg2+
(
Log k)
1
1.99 ± 0.02
–
4.17 ± 0.02
0.0052
Negligible
Negligible
Negligible
Log k12
6.88 ± 0.01

5
66
P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
À5
Fig. 10. Optical change (under 365 nm UV light) upon addition of one equivalent acetate salt of various cations into a solution of 1 ([1] = 2.5 Â 10 M) in MeOH. From left to
right; A = Free ligand, B = Ni2 , C = Cu , D = Hg , E = Co , F = Cd , G = Mn , H = Fe , I = Pb , J = Zn , K = Ag , L = Cr .([1] = [M ] = 2.5 Â 10 M).
+
2+
2+
2+
2+
2+
3+
2+
2+
+
3+
n+
À5
3
.7. Fluorescence studies
mental addition of a solution of the metal ion (Ni2+ or Cu2+) into a
solution of the ligand produced a gradual decrease in the fluores-
cence band intensity at 530 nm (Fig. 12). The fluorescence titration
data was used to calculate the limit of detection value for both cop-
per and nickel ions. Linear fluorescence intensity versus metal ion
concentration plot was drawn for both copper and nickel ions. The
In order to investigate the metal ion selectivity of the ligand 1,
fluorescence studies were conducted in methanol. Solutions of the
ligand and different metal ions in equimolar ratios were exposed to
UV light (365 nm, 4 W). A distinct change in the fluorescence
intensity was observed in a solution containing nickel and copper
ions (Fig. 10). No change in fluorescence intensity was observed
plot yielded a LOD value of 1.04
lM for copper ions and 0.82 lM
for nickel ions (Figs. S28 and S29).
in solution containing Hg2 , Mn and Cr ions and the free ligand
+
2+
3+
1
, which displayed yellow color. The solutions containing other
3
.8. Optical response of the crystals of 1–Cu and 1–Ni complex
metal ions did not show any visible color. The blue color visible
on the solution is due to the color of the UV light (Fig. 10).
Further, solutions of the ligands and the metal ions were also
analyzed using fluorescence spectroscopy. On excitation at
The optical nature of synthesized metal complexes was also
investigated using UV–Vis spectroscopy in methanol. The UV–Vis
spectrum of metal complex 1–Cu displayed a broad absorption
band in the region of 365 nm, while 1–Ni complex displayed an
absorption band in the higher wavelength region at 410 nm. The
absorption spectra of synthesized metal complexes are shown in
Fig. 13. The nickel complex in methanol produced a single broad
absorption band near 410 nm, which was observed to be similar
to the absorption band observed in a solution of 1 and nickel ions
in 1:2 mole ratio (Fig. 13). However, the absorption band of the
copper complex near 370 nm in methanol is almost similar to
3
70 nm, the emission was observed at a longer wavelength
(
530 nm). The fluorescence band at 530 nm decreased in intensity
2+
2+
in a solution containing Cu or Ni ions in methanol (Fig. 11).
Other metal ions did not produce any change in the emission
response, which indicated the selective response of the ligand 1.
In addition, titration experiments between the ligand and the
2
+
2+
metal ions (Ni and Cu ) were also performed in methanol. Incre-
À5
Fig. 11. The change in fluorescence spectra of 1 ([1] = 2.5 Â 10 M) upon addition
n+
2+
2+
2+
of one equivalent acetate salt of different cations in MeOH. M = Hg , Zn , Cd
,
2+
3+
2+
+
2+
3+
Mn , Fe , Pb , Ag , Co , Cr .For simplicity, spectra of only a few important
Fig. 13. UV–Vis spectra of synthesized metal complexes 1–Cu and 1–Ni in
cations are shown, kex = 370 nm.
methanol. [1–Cu ] = 2.11 Â 10 M. [1–Ni ] = 1.25 Â 10À5 M.
2
+
À5
2+
Fig. 12. The change in fluorescence spectra of 1 ([1] = 2.5 Â 10À5 M) upon incremental addition of Cu2+ and Ni2+ in methanol.

P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
567
one produced by a solution containing an equimolar ratio of copper
3.9. Thermal studies
ions and 1 in methanol.
Metal complexes often show interesting fluorescence response
45]. Therefore, we explored the optical response of the synthe-
The thermal stability of metal complexes was assessed in 35–
800 °C temperature range using thermogravimetric analysis
(TGA). In the TGA plot of 1–Cu, a small decrease in weight loss of
around 5.7% was observed at 140 °C, which may be due to the
release of one water and one acetate molecule [51]. Another
weight loss of around 24% was observed at 210 °C owing to the loss
of one receptor unit. The weight loss in case of 1–Cu was noticed at
380 °C till it attained stability at 620 °C (Figs. 16, 17, S30). The
weight loss at 380 °C may be due to loss of residual solvent from
the copper complex. In the TGA plot of 1–Ni, the decomposition
begins after 115 °C. A weight loss of 2.5% in 115 °C region may
be attributed to the release of one acetonitrile molecule [52]. The
weight loss of 35% at 260 °C may be attributed to the loss of four
[
sized metal complexes using fluorescence spectroscopy in solid
state and in solution (methanol). The 1–Cu and 1–Ni complexes
were analyzed using solid-state fluorescence spectroscopy using
excitation at 365 nm (5 nm slit width). The 1–Cu and 1–Ni com-
plexes produced a weak emission band at 592 nm (Fig. 14a). The
quantum yield of the fluorescence in the solid state was calculated
using the method reported earlier [46], which yielded 0.25 for 1–Ni
complex and 0.24 for the 1–Cu complex.
The fluorescence curves of the different metal complexes were
also recorded on excitation at 365 nm wavelength with slit widths
at 5 nm in methanol (Fig. 14b). The metal complex 1–Cu displayed
an emission band at 420 nm and 530 nm (Fig. 14). However, a solu-
tion of 1–Ni complex in methanol displayed a band at 510 nm
emission intensity with higher intensity in comparison to the
intensity of the emission band observed in copper ions (Fig. 14b).
Similar differences in the fluorescence intensity were observed in
the solid state. The result in solution indicated an efficient quench-
ing of the fluorescence signal by copper ions perhaps due to para-
magnetic effect as reported earlier [47,48].
Since metal complexes 1–Cu and 1–Ni displayed fluorescence
(
quenching) response in methanol, we explored the sensitivity
of the metal complexes by comparing the absorbance response
with fluorescence intensity [49]. Therefore, we plotted the absor-
bance values and the corresponding fluorescence response as
shown in Fig. 15. The metal complex 1–Cu displayed stokes shift
value of 55 nm. Similarly, the metal complex 1–Ni displayed
stokes shift value of around 100 nm in methanol. High values of
Stokes shifts are advantageous for signal recognition purposes
Fig. 16. TGA of 1–Cu and 1–Ni complex.
[
50].
Fig. 14. The fluorescence response of synthesized metal complexes 1–Cu and 1–Ni [a] in solid state [b] in methanol. kex = 365 nm.
Fig. 15. Comparison of absorbance and fluorescence response of 1–Cu and 1–Ni in methanol.

5
68
P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
water, six acetate and acetonitrile molecule (Figs. 16, 17, S30).
Around 20% decrease in weight loss at 435 °C was observed in
structure displayed two different types of short contacts, which
are formed due to complex formation (Figs. S35 and S36). How-
ever, in the case of 1–Ni complex no oxygen to pi interaction
was observed in the crystal structure (Fig. S37). No shift in the
1–Ni complex, which may be assigned to the loss of the single recep-
tor unit. After removal of water and acetate units, the metal complex
dismantled completely, this confirmed that the existence of water
and acetate fragments in the crystal lattice played a unique role
towards stabilization of the entire supramolecular system.
Similar observations were obtained from the DTA plot of the
synthesized metal complexes. The DTA plot of metal complexes
are shown in Fig. 17.
3
OCH signal was observed, which indicated that this oxygen atom
is not involved in any type of interaction with the metal ion. The
1
crystal structure also supported H NMR results, which indicated
3
no interactions between the OCH group and the metal ions. Coor-
1
dinated water and acetate molecules were also observed in the H
NMR spectra of both 1–Cu and 1–Ni complexes. The aromatic
region of 1–Cu complex displayed much more complex signal pat-
1
terns in comparison to the H-NMR signals observed in the spectra
3.10. NMR studies
of ligand 1, while such a complex signal pattern in the aromatic
region was not observed in the H-NMR spectra of 1–Ni complex.
1
To investigate the complex formation between 1 and the metal
This observed complex signal pattern in 1–Cu complex may be
attributed to the short intermolecular interaction between differ-
ent ligand units.
1
ions in solution,
H NMR spectra were recorded in CDCl
3
1
(
Figs. S31–S33). A comparison of the H NMR spectra of the ligand
1
and its complex with copper or nickel ions indicated a significant
difference in the aromatic and aliphatic signals (Figs. 18 and 19). A
small broadening of peak was observed in case of copper ions due
3.11. Optical response
to the paramagnetic effect of copper ions (Fig. 18). The OACH
group signal that appears near d 2.76 ppm in the free ligand shifted
to d 3.01 and d 3.39 ppm in 1–Cu complex, while it shifted to d
2
The synthesized ligand 1 was observed to be highly fluorescent
due to the presence of morpholine moiety in its structure. In an
attempt to check the optical performance of the synthesized ligand
, advanced writing discs with various colors were developed
Fig. 20). Solutions of the ligand 1 and metal ions in equimolar
ratios were prepared. A word SSC was written on filter paper using
free ligand 1 and a solution of the ligand-containing nickel or cop-
per ions. The word written using free ligand displayed faint color,
while the word written using a solution of the free ligand 1 and
copper or nickel ions produced yellow colored letters. The letters
were exposed to 365 nm UV light. Upon exposure to UV light,
the letters written using free receptor displayed a glow, while
2
.77 ppm in 1–Ni complex. A look at the intermolecular interac-
1
(
tions in the crystal structure revealed no direct interactions
between the metal ions and the oxygen atom of the morpholine
unit. The morpholine unit in the ligand displayed a weak short con-
tact with the ACH of ester group (Fig. S34). In 1–Cu complex, two
3
different types of interactions were observed that involved oxygen
atom of the morpholine unit. The morpholine unit in the crystal
1-Ni Complex
1
9
8
7
6
5
4
3
2
1
Fig. 17. DTA plot of complexes 1–Cu, 1–Ni.
Fig. 19. A comparison of the 1H NMR spectra of 1 and 1–Ni complex recorded in
CDCl
3
.
1-Cu complex
1
8
6
4
2
0
Fig. 18. A comparison of the 1H NMR spectra of 1 and 1–Cu complex recorded in
CDCl
Fig. 20. The optical response of 1 and its complexes from methanol solution [a]
under daylight, [b] under 365 nm UV light.
3
.

P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
569
the word written using a solution of the free ligand 1 and copper or
nickel ions produced a reduction in emission intensity (Fig. 20b).
[14] D. Reinhard, W.-S. Zhang, Y. Vaynzof, F. Rominger, R.R. Schröder, M. Mastalerz,
Triptycene-based porous metal-assisted salphen organic frameworks:
influence of the metal ions on formation and gas sorption, Chem. Mater. 30
(
2018) 2781.
15] T.N. Mandal, A. Karmakar, S. Sharma, S.K. Ghosh, Metal-organic frameworks
MOFs) as functional supramolecular architectures for anion recognition and
sensing, Chem. Rec. 18 (2018) 154.
[
4
. Conclusions
(
It was demonstrated that the substituted methyl 3-hydroxy-2-
[16] B. Champin, P. Mobian, J.-P. Sauvage, Transition metal complexes as molecular
machine prototypes, Chem. Soc. Rev. 36 (2007) 358.
naphthoate can serve as a building block for the development of
interesting crystalline frameworks, which can accommodate tran-
sition metal ions such as copper (II) and nickel(II). We have suc-
cessfully displayed the optical and fluorescent nature of metal
complexes with dark yellow and light green coloration. Such metal
complexes may find potential applications in functional devices
owing to their superior optical response.
[
17] M.-A. Haga, K. Kobayashi, K. Terada, Fabrication and functions of surface
nanomaterials based on multilayered or nanoarrayed assembly of metal
complexes, Coord. Chem. Rev. 251 (2007) 2688.
[
18] Y.-J. Yuan, Z.-T. Yu, D.-Q. Chen, Z.-G. Zou, Metal-complex chromophores for
solar hydrogen generation, Chem. Soc. Rev. 46 (2017) 603.
[
19] V. Balzani, S. Campagna, G. Denti, A. Juris, S. Serroni, M. Venturi, Designing
dendrimers based on transition-metal complexes. Light-harvesting properties
and predetermined redox patterns, Acc. Chem. Res. 31 (1998) 26.
20] V. Balzani, A. Juris, M. Venturi, S. Campagna, S. Serroni, Luminescent and
redox-active polynuclear transition metal complexes, Chem. Rev. 96 (1996)
759.
[
[
Acknowledgments
21] K. Chakarawet, P.C. Bunting, J.R. Long, Large anisotropy barrier in
a
tetranuclear single-molecule magnet featuring low-coordinate cobalt
centers, J. Am. Chem. Soc. 140 (2018) 2058.
Authors sincerely thank SERB, New Delhi, India for financial
support (EMR/2016/005022). Authors are thankful to the Director,
USIC University of Delhi and Principal, St. Stephen’s College for
instrumental facilities and the necessary infrastructure. The
authors are also thankful to Mr. KP for some help during the exper-
iments. The authors dedicate this paper to the memory of Late Dr.
Usha Arora (Deshbandhu College, University of Delhi).
[22] R. Bo cˇ a, C. Rajnák, J.N. Titiš, D.A. Valigura, Field supported slow magnetic
relaxation in a mononuclear Cu (II) complex, Inorg. Chem. 56 (2017) 1478.
23] K. Kalyanasundaram, M. Grätzel, Applications of functionalized transition
metal complexes in photonic and optoelectronic devices, Coord. Chem. Rev.
177 (1998) 347.
[
[
[
[
24] Z. Liu, W. He, Z. Guo, Metal coordination in photoluminescent sensing, Chem.
Soc. Rev. 42 (2013) 1568.
25] Q. Zhao, C. Huang, F. Li, Phosphorescent heavy-metal complexes for
bioimaging, Chem. Soc. Rev. 40 (2011) 2508.
26] K.K.-W. Lo, S.P.-Y. Li, Luminescent Transition-Metal Complexes as
Biomolecular and Cellular Probes, Molecular Design and Applications of
Photofunctional Polymers and Materials, Royal Society of Chemistry
Cambridge, UK, 2012, p. 500.
27] C.E. McGhee, K.Y. Loh, Y. Lu, DNAzyme sensors for detection of metal ions in
the environment and imaging them in living cells, Curr. Opin. Biotechnol. 45
(2017) 191.
[28] I. Stassen, N. Burtch, A. Talin, P. Falcaro, M. Allendorf, R. Ameloot, An updated
roadmap for the integration of metal–organic frameworks with electronic
devices and chemical sensors, Chem. Soc. Rev. 46 (2017) 3185.
29] R. Kaushik, A. Ghosh, D.A. Jose, Recent progress in hydrogen sulphide (H2S)
sensors by metal displacement approach, Coord. Chem. Rev. 347 (2017) 141.
30] Y. Agnus, R. Louis, R. Weiss, Bimetallic copper (I) and-(II) macrocyclic
complexes as mimics for type 3 copper pairs in copper enzymes, J. Am.
Chem. Soc. 101 (1979) 3381.
Appendix A. Supplementary data
CCDC 1858233, 1858234, 1858235 contains the supplementary
crystallographic data for (1), (1–Cu), (1–Ni). These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/re-
trieving.html, or from the Cambridge Crystallographic Data Centre,
[
1
2 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033;
or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data to this
article can be found online at https://doi.org/10.1016/j.poly.2019.
[
[
0
7.044.
[
31] S. Blanchard, L. Le Clainche, M.N. Rager, B. Chansou, J.P. Tuchagues, A.F. Duprat,
Y. Le Mest, O. Reinaud, Calixarene-based copper (I) complexes as models for
monocopper sites in enzymes, Angew. Chem. Int. Ed. 37 (1998) 2732.
32] E.L. Que, D.W. Domaille, C.J. Chang, Metals in neurobiology: probing their
chemistry and biology with molecular imaging, Chem. Rev. 108 (2008) 1517.
33] B.-E. Kim, T. Nevitt, D.J. Thiele, Mechanisms for copper acquisition, distribution
and regulation, Nat. Chem. Biol. 4 (2008) 176.
References
[
1] C.B. Aakeröy, N. Schultheiss, J. Desper, Directed supramolecular assembly of
infinite 1-DM (II)-containing chains (M = Cu Co, Ni) using structurally
bifunctional ligands, Inorg. Chem. 44 (2005) 4983.
[
[
[
[
[
[
2] N. Kumar, A.K. Suri, Morpholine complexes of copper(II) alkanoates and
chloroacetates, Transit. Met. Chem. 4 (1979) 345.
34] K.D. Karlin, Z. Tyeklar, Bioinorganic Chemistry of Copper, Springer Science &
Business Media, 2012.
35] S.W. Ragsdale, M. Kumar, Nickel-containing carbon monoxide dehydrogenase/
acetyl-CoA synthase, Chem. Rev. 96 (1996) 2515.
[
3] B. Panunzi, S. Concilio, R. Diana, R. Shikler, S. Nabha, S. Piotto, L. Sessa, A. Tuzi,
U.
Caruso,
Photophysical
properties
of
luminescent
zinc(II)-
pyridinyloxadiazole complexes and their glassy self-assembly networks, Eur.
J. Inorg. Chem. 2018 (2018) 2709.
36] Z. Li, Y. Ohki, K. Tatsumi, Dithiolato-bridged dinuclear iron–nickel complexes
[
4] R. Diana, B. Panunzi, R. Shikler, S. Nabha, U. Caruso, Highly efficient dicyano-
phenylenevinylene fluorophore as polymer dopant or zinc-driven self-
assembling building block, Inorg. Chem. Commun. 104 (2019) 145.
5] R. Diana, U. Caruso, S. Concilio, S. Piotto, A. Tuzi, B. Panunzi, A real-time
tripodal colorimetric/fluorescence sensor for multiple target metal ions, Dyes
Pigm. 155 (2018) 249.
[
Fe(CO)2(CN)2(l-SCH2CH2CH2S)Ni(S2CNR2)]-modeling the active site of
[
NiFe] hydrogenase, J. Am. Chem. Soc. 127 (2005) 8950.
[
[
37] C.K. Prier, D.A. Rankic, D.W. MacMillan, Visible light photoredox catalysis with
transition metal complexes: applications in organic synthesis, Chem. Rev. 113
[
(
2013) 5322.
38] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A. Howard, H. Puschmann, OLEX2: a
complete structure solution, refinement and analysis program, J. Appl.
Crystallogr. 42 (2009) 339.
[
[
[
6] N.H. Piacquadio, M.A. Blesa, The interaction of morpholine with metal ions—I:
Copper complexes, Polyhedron 1 (1982) 437.
7] N. Kumar, A.K. Suri, Thermal studies of bis-morpholine complexes of copper(II)
carboxylates, Thermochim. Acta 41 (1980) 383.
8] M.S. Eberhart, L.M.R. Bowers, B. Shan, L. Troian-Gautier, M.K. Brennaman, J.M.
Papanikolas, T.J. Meyer, Completing a charge transport chain for artificial
photosynthesis, J. Am. Chem. Soc. 140 (2018) 9823.
[
39] G.M. Sheldrick, SHELXT–Integrated space-group and crystal-structure
determination, Acta Crystallogr., Sect: A 71 (2015) 3.
[
40] C.F. Macrae, I.J. Bruno, J.A. Chisholm, P.R. Edgington, P. McCabe, E. Pidcock, L.
Rodriguez-Monge, R. Taylor, J.V. Streek, P.A. Wood, Mercury CSD 2.0–new
features for the visualization and investigation of crystal structures, J. Appl.
Crystallogr. 41 (2008) 466.
[
9] Y.-F. Wang, L.-P. Wang, S.-P. Wang, Y.-L. Li, X.-L. Zhou, Four Zn/Pb complexes
based on pyridine containing mercapto-triazole ligand: syntheses, structures,
and luminescent properties, Z. Anorg. Allg. Chem. 644 (2018) 1164.
[
[
[
41] P.K. Mehrotra, R. Hoffmann, Cu (interactions). Bonding relationships in dl0-
d1O systems, Inorg. Chem. 17 (1978) 2187.
42] R. Thakuria, N.K. Nath, S. Roy, A. Nangia, Polymorphism and isostructurality in
sulfonylhydrazones, CrystEngComm 16 (2014) 4681.
[
10] J.-P. Sauvage, Transition metal-containing rotaxanes and catenanes in motion:
toward molecular machines and motors, Acc. Chem. Res. 31 (1998) 611.
11] L.I. Belen’kii, Y.B. Evdokimenkova, Chapter six – The literature of heterocyclic
chemistry, Part XIV, 2014, in: E.F.V. Scriven, C.A. Ramsden (Eds.), Advances in
Heterocyclic Chemistry, Academic Press, 2017, pp. 245–301.
[
43] S.K. Wolff, D.J. Grimwood, J.J. McKinnon, M.J. Turner, D. Jayatilaka, M.A.
Spackman, CrystalExplorer (Version 3.1), University of Western Australia,
2012.
[
[
12] Y.-B. Huang, J. Liang, X.-S. Wang, R. Cao, Multifunctional metal–organic
framework catalysts: synergistic catalysis and tandem reactions, Chem. Soc.
Rev. 46 (2017) 126.
13] K. Kim, S. Kim, S.N. Talapaneni, O. Buyukcakir, A.M.I. Almutawa, K.
Polychronopoulou, A. Coskun, Transition metal complex directed synthesis
of porous cationic polymers for efficient CO2 capture and conversion, Polymer
[
[
44] P. Gans, A. Sabatini, A. Vacca, Investigation of equilibria in solution.
Determination of equilibrium constants with the HYPERQUAD suite of
programs, Talanta 43 (1996) 1739.
45] H.-L. Jiang, Y. Tatsu, Z.-H. Lu, Q. Xu, Non-, micro-, and mesoporous metalÀ
organic framework isomers: reversible transformation, fluorescence sensing,
and large molecule separation, J. Am. Chem. Soc. 132 (2010) 5586.
1
26 (2017) 296.

5
70
P.R. Sahoo et al. / Polyhedron 171 (2019) 559–570
[
46] L.-O. Pålsson, A.P. Monkman, Measurements of solid-state photoluminescence
quantum yields of films using a fluorimeter, Adv. Mater. 14 (2002) 757.
47] D. Udhayakumari, S. Velmathi, Y.-M. Sung, S.-P. Wu, Highly fluorescent probe
for copper (II) ion based on commercially available compounds and live cell
imaging, Sens. Actuators, B 198 (2014) 285.
48] Z.-C. Liu, Z.-Y. Yang, T.-R. Li, B.-D. Wang, Y. Li, D.-D. Qin, M.-F. Wang, M.-H. Yan,
An effective Cu(II) quenching fluorescence sensor in aqueous solution and 1D
chain coordination polymer framework, Dalton Trans. 40 (2011) 9370.
49] A. Coskun, E.U. Akkaya, Ion sensing coupled to resonance energy transfer: a
highly selective and sensitive ratiometric fluorescent chemosensor for Ag (I)
by a modular approach, J. Am. Chem. Soc. 127 (2005) 10464.
[50] P. Hou, S. Chen, H. Wang, J. Wang, K. Voitchovsky, X. Song, An aqueous red
emitting fluorescent fluoride sensing probe exhibiting a large Stokes shift and
its application in cell imaging, Chem. Commun. 50 (2014) 320.
[51] P. Kanoo, T.K. Maji, Temperature-controlled synthesis of metal-organic
coordination polymers: crystal structure, supramolecular isomerism, and
porous property, Cryst. Growth Des. 9 (2009) 4147.
[
[
[52] G. Neville, H. Beckstead, J. Cooney, Thermal analyses (TGA and DSC) of some
spironolactone solvates, Fresenius J. Anal. Chem. 349 (1994) 746.
[