Study on structure and properties of two metal coordination polymers prepared by 3,5-Bis (4-carboxy-phenoxy)benzoic acid

Accepted Manuscript Study on structure and properties of two metal coordination polymers prepared by 3,5-Bis (4-carboxy-phenoxy)benzoic acid Xin Liu, Lun Zhao, Changjiang Zhao, Lingshu Meng, Chang Liu PII:

S0022-2860(19)30355-2

DOI:

https://doi.org/10.1016/j.molstruc.2019.03.076

Reference:

MOLSTR 26345

To appear in:

Journal of Molecular Structure

Received Date: 22 December 2018 Revised Date:

20 March 2019

Accepted Date: 23 March 2019

Please cite this article as: X. Liu, L. Zhao, C. Zhao, L. Meng, C. Liu, Study on structure and properties of two metal coordination polymers prepared by 3,5-Bis (4-carboxy-phenoxy)benzoic acid, Journal of Molecular Structure (2019), doi: https://doi.org/10.1016/j.molstruc.2019.03.076. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Study on Structure and Properties of Two Metal Coordination Polymers Prepared by 3,5-Bis (4-carboxy-phenoxy)Benzoic Acid

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Xin Liu, Lun Zhao*, Changjiang Zhao, Lingshu Meng, Chang Liu College of Chemistry, Changchun Normal University, Changchun, 130032, Jilin, P. R. China; *Correspondence: E-mail: [email protected]; Tel.: +86-431-86168903(L Zhao)

Abstract: Two new metal-organic frameworks (MOFs) [Zn(HBCPBA)(tpim)]·H2O (1) and [Co(HBCPBA)(tpim)] (2) were achieved by reactions of corresponding metal salt with mixed organic

ligand

of

3,5-Bis(4-carboxy-phenoxy)benzoic

acid(H3BCPBA)

and

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2,4,5-tris(4-pyridyl)imidazole (tpim). These crystals were clearly characterized by elemental analysis, IR spectra, X-ray powder diffraction (PXRD) as well as X-ray single-crystal diffraction. The crystal structures showed that the compound 1 crystallizes in the monoclinic

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system, with P21/c space group,displays a two-dimensional network structure, the compound 2 crystallizes in the orthorhombicsystem, with Pbca space group, also exhibits a two-dimensional network structure, which has a zero-dimensional ring structure link Co(II) ion by N-containing ligand tpim. Remarkably, 1 can act as fluorescence probe for sensing Fe3+ ion and 2 has electrochemically active substances with good electrochemical reversibility. Keywords: 3,5-Bis(4-carboxy-phenoxy)benzoic acid(H3BCPBA);

2,4,5-tris(4-pyridyl)imidazole; Coordination polymers; Fluorescence; Electrochemical

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properties 1.Introduction

Metal-organic frameworks (MOFs) are emerging class of porous materials with tailorable

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structures, the coordination polymers (CPs) have drawn more and more concerns ofchemists and materials scientists not only for their interesting structures[1,2], but also for their potential applications in the field of gas storage[3], separation[4],luminescence[5], catalysis[6],

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magnetic properties[7], electrocatalysis[8]. The self-assembly of CPs depend on the coordination type of the metal ions, chemical structure of organic ligand[9], as well as other factors that influence the synthesis process, such as temperature, pH value of the solution[10], and the solvent system[11].It is still a great challenge to synthesize CPs with predictable structuresand desired properties[12]. There are various synthesis methods of coordination polymer, but hydrothermal/solvothermal conditions are the most classical synthetic methods[13], which are mainly due to their low cost[14], high crystallinity and good stability of crystal formation. The flexibility of the organic multi-carboxy ligands endowed the constructed CPs tunable structures, which further have influence on the properties.Because of the diversity of coordination,H3BCPBA, as a ligand which containing both flexible backbones and various coordination modes[15,16], can be react with transition metal ions and organic ligands to form a variety of spatial topologies[17]. In addition, the coordination ability in ligand is very

ACCEPTED MANUSCRIPT well of O atoms and metal ions, which makes a good choice to constructcoordination polymers. For example, Shi designed and synthesized three new CPs by H3BCPBA and metal ions, [Ce(L)]·4.5H2O, [Nd(L)]·4.5H2O and [Yb(L)(H2O)2]·3.5H2O, all compounds exhibited efficient multifunctional luminescent materials for highly selective and sensitive sensing of metal ions, anions and small organic molecules, especially for Fe3+[18]. Cui and co-workers the reactions of Co salt with H3BCPBA in the presence or absence of auxiliary ligands six

novel

CPs,

{[Co(H2BCPBA)2(H2O)4]}n,

{[Co3(BCPBA)2(dpe)(μ2-H2O)4]·2H2O·2DMF}n,

{[Co(HBCPBA)(bipy0.5)2·(H2O)]}n,

{[Co3(BCPBA)2(pdp)·(μ2-H2O)4]·2DMF}n,

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generate

{[Co3(BCPBA)2(bpe)(μ2-H2O)4]·2DMF}n, {[Co2 (HBCPBA)2(bpp)·(μ2-H2O)2]·H2O·2DMF}n, the photochemical properties are performed in the solid state at room temperature. Magnetic susceptibilities indicated that compounds exhibit antiferromagnetic coupling between adjacent Co(II) ions[19].

In this work, two new CPs have been successfully synthesized via the utilization of

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H3BCPBA and tpim ligand with transition metal salts. Namely, [Zn(HBCPBA)(tpim)]·H2O (1), [Co(HBCPBA)(tpim)] (2) have been achieved, the structure of ligands as shown in Scheme1. They were characterized by X-ray single-crystal diffraction, thermal and elemental analyses. investigated, respectively.

HOOC

O

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Accordingly, the fluorescence property of 1 and the electrochemical property of 2 were

HN

COOH HOOC

O

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N

3,5-bi(4-carboxy-phenoxy) benzoic acid (H3 BCPBA)

N

N

N

2,4,5-tris(4-pyridyl)imidazole(tpim)

Scheme 1 Molecular structure of ligands

2.Experimental section

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2.1 Materials and methods

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All chemical reagents were commercially available without further purification. Elemental analyses (C, H and N) were carried out with a Perkin-Elmer 240C analyzer. IR spectra (4000-400 cm-1) was recorded from KBr Pellets with a Thermo Nicolet Avatar 360 IR spectrometer. Powder X-ray diffraction (PXRD) data were collected on D2 PHASER A26-X1 XRD diffractometer of Bruker Corporation. TGA was performed on a Perkin-Elmer TG-7 analyzer heated from room temperature to 800°C under flowing nitrogen. The fluorescence spectra was detected on a HITACHIF-7000 spectrometerat room temperature. The electrochemical property was measured by a DF-2002 electrochemical workstation at 25 °C. 2.2 Synthesis of[Zn(HBCPBA)(tpim)]·H2O (1). A mixture of Zn(NO3)2·6H2O (0.0297g, 0.1mmol), H3BCPBA (0.0394 g, 0.1 mmol), tpim (0.0317 g, 0.1 mmol) and 10 mL H2O was sealed in a 25 mL Teflon-lined stainless steel vessel. After stirring, which was heated at 160 °C for 3 days under autogenous pressure. After cooling to room temperature at a rate of 10 °C·h−1, large quantities of colorless block crystals were obtained and the crystals were filtered off, washed with ethyl alcohol absolute, and dried under ambient conditions. Crystals of 1 were obtained with the yield of 58% (based on

ACCEPTED MANUSCRIPT tpim). Elemental analysis calcd for C39H26N5O9Zn(%): C,60.51; H,3.39; N,9.04. Found: C,60.17; H, 3.31; N,9.15.IR (KBr, cm-1): 3112 (w), 1682 (w), 1578 (s), 1515 (s), 1482 (s), 1391 (s), 1307 (m), 1262 (m), 1171 (w), 1119 (w), 1061 (s), 1003 (w), 963 (w), 926 (w), 842 (m), 770 (m), 700 (w), 679 (w), 654 (w), 537 (w), 421 (w). 2.3 Synthesis of[Co(HBCPBA)(tpim)](2). Preparation of 2 was similar to 1 except that CoCl2·6H2O (0.0238 g, 0.1 mmol) was used

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instead of Zn(NO3)2·6H2O and DMF/H2O solvent (8:2, 10 mL) was used substitute H2O. Then stirring, which was heated at 80 °C for 3 days under autogenous pressure.Compound of 2 was obtained purple-color block crystals with the yield of 52% (based on tpim). Elemental analysis calcd for C39H24CoN5O8(%): C,62.49; H,3.23; N,9.34. Found: C,63.17; H, 3.28; N,9.65.IR (KBr, cm-1): 3131 (m), 3054 (w), 1676 (s), 1585 (s), 1515 (s), 1385 (s), 1307 (s), 1268 (s), 1071 (s), 1119 (s), 1061 (s), 1003 (s), 964 (m), 932 (m), 854 (s), 828 (s), 770 (s), 700 (s), 654 (s), 615 (w), 544

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(m), 472 (w), 414 (s). 2.4 X-ray crystallography

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Crystallographic diffraction data of compounds 1 and 2 were collected on a Bruker SMART APEXIICCD diffractometer with Mo-Kα radiation (λ=0.71073 Å) at room temperature. All the structures were solved by Direct Method of SHELXL-97 program.The coordinates of non-hydrogen atoms were refined by the anisotropy of theatoms. The relevant crystallographic data and refinement parameters of compounds are presented in Table 1. Table1. Crystal data and structure refinement for 1 and 2

Compound 2

1868085

1868086

C39H26N5O9Zn

C39H24CoN5O8

774.02

749.57

Monoclinic

Orthorhombic

Space group

P21/c

Pbca

a/ A

10.6676(7)

22.1028(17)

b/ A

13.8641(9)

13.1201(11)

c/ A

24.2711(16)

24.2715(18)

α/(°)

90

90

β/(°)

93.0210(10)

90

γ/(°)

90

90

V/nm3

3584.6(4)

7038.5(10)

Z

4

8

Dc/(g⋅cm−3)

1.431

1.415

F(000)

1580

3072

CCDC No. Molecular Formula Fw

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Crystal system

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Compound 1

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1.038

0.999

R1/wR2[ I>2σ(I)]

0.0510, 0.1359

0.0528, 0.1303

R1/wR2 (all data)

0.0711, 0.1459

0.1237, 0.1650

3.Results and discussion

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3.1 Structure description of 1 X-ray single-crystal diffraction analysis reveals that compound1 crystallizes in the monoclinic system, P21/c space group. As shown in Fig.1, the asymmetric unit of 1 comprises one crystallographic independent Zn(II) ion, one carboxylic acid (HBCPBA)2- ligand, one tpim ligand and one uncoordinated water molecule. In this unit, the Zn(II) ion is tetra-coordinated, coordinated by two O atoms from two

(HBCPBA)2- ligands and two N atoms from two tpim

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ligands, displaying a distorted tetrahedron geometry. In this unit, Zn(II) ionis connected by two carboxyl groups of the (HBCPBA)2- ligands, which shows a monodentate coordination mode, Z-O bond lengths range from 1.9713(18) to 1.927(2) Å and the bond distances of Zn-N

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are from 2.027(2) to 2.051(2) Å. In compound 1, the Zn(II) ionisconnected by

(HBCPBA)2-

ligandand N-containing ligand tpim, constructing a one-dimensional(1D) chain, then the 1D chains are connected by the Zn(II) ion to forma 2D layer (Fig. 1b). Furthermore, with the help of N–H⋯O [N3–H3⋯O8#5 =2.711(3)Å, symmetry codes: #5:-x+3,-y+1,-z+2], finally given a

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stable 3D supramolecular architecture (Fig. 1cd).

Fig. 1 (a) The coordination environment of Zn(II) ion in 1. (b) Two-dimensional layered framework structure. (c)Two-dimensional network structure. (d) Three-dimensional supramolecular network.

ACCEPTED MANUSCRIPT 3.2 Structure description of 2 The crystal data analysis indicates that 2 crystallizes in the orthorhombic system, Pbca space group. As depicted in Fig.2a, the asymmetric unit contains one crystallographic independent Co(II) ion, one carboxylic acid (HBCPBA)2- ligand, and one tpim ligand. The center Co(II) ionis hexa-coordinated, surrounded by four O atoms from two (HBCPBA)2ligands and two N atoms from two tpim ligands, forming a distorted octahedron geometry.

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In this structure, the two carboxyl groups of the (HBCPBA)2- ligandare bridged Co(II) ion by bidentate chelate mode. The Co-O distances fall in the range of 2.056(2) to 2.178(2) Å, the Co–N distances fall in the range of 2.070(3) to 2.111(3) Å. In compound 2, the Co(II) ionis bonded to the (HBCPBA)2- ligand to form a 1D chain, and Co(II) ionis linked to N-containing ligand tpim to generate a 0D ring, different carboxyl acid chains are connected two metal junctions of 0D ring to form a 2D layer structure(Fig. 2bc). Furthermore, with the help of

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stable 3D supramolecular architecture (Fig. 2d).

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N–H⋯O [N2–H2A⋯O2#4 =2.860(3)Å, symmetry codes: #5:-x+3/2,y-1/2,z], finally given a

Fig. 2 (a) Coordination environment of Co(II) ion in 2. (b) Two-dimensional layer framework structure. (c) Two-dimensional layer network topology. (d) Three-dimensional network topology.

ACCEPTED MANUSCRIPT 4. PXRD Analysis The phase purity of compounds 1 and 2 were confirmed by PXRD measurements at room temperature, and each PXRD pattern of the synthesized sample is consistent with the

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simulated one, which implying that 1 and 2 belong to the pure phase(Fig.3).

Compound1

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a

b 10

20

30

40

2theta

50

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0

Fig.3Experimental (a) and simulated (b) PXRD patterns of compound 1 and 2

5.Thermal Analysis

In order to estimate the stability of the compounds 1 and 2, Perkin-Elmer TG-7 analyzer was carried out under nitrogen at a heating rate of 10 °C·min–1range from room temperature to 800 °C (Fig. 4). For compound 1, the framework and ligand begins to decomposition at

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400-520 °C, the framework can maintain stable after 550 °C. Finally, the remaining weight corresponds to the formation of 6.56% ZnO(calcd. 10.52%). Compound2 can maintain the integrity crystal framework until 490 °C, without loss of quality. Then, the organic framework begins to collapse at the range of 490-520 °C. In the end, the remaining weight corresponds to

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the formation of 11.26% CoO(calcd. 10.00%).

100

80

compound 1

compound 2

80

weight(%)

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weight(%)

100

60

40

20

60

40

20

0

0

0

100

200

300

400

500

0

600

700

800

Temperature( C)

0

100

200

300

400

500

0

600

700

800

Temperature( C)

Fig.4 The TGA diagrams of compound1 and 2

6. Fluorescence 6.1 Luminescent measurements and discussions The solid state luminescence properties of compound 1 and ligand were explored at room

ACCEPTED MANUSCRIPT temperature. As shown in Fig.5, the emission spectra exhibits strong emission peaks at 304 nm (λex=365 nm) for the H3BCPBA ligand and 275 nm (λex=405 nm) for the tpim, respectively. While compound1 exhibits emission at 425 nm(λex=284 nm). The central metal ion of 1 is Zn(II) ion, due to the d10 configuration, it is difficult to oxidized or reduced. Meanwhile, the excitation and emission wave of 1 are similar to the tipm ligand. Indicated that luminescence of 1 is attributed to the N-containing ligand tpim, the ligand is belonging to π*→π electron transition emission. Compared to the emission peak of the tpim ligand, the emission of 1 is

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undergoing slight red-shift.

3500 3000

2000 1500

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Intensity(a.u)

2500

tpim

1000

0 350

compound 1

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H 3BCPBA

500

400

450

500

550

wavelength(nm)

Fig.5 Solid-state emission spectra of compound 1, H3BCPBA and tpim at room temperature.

6.2 Selective Detection of Fe3+ion

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Through the reported previous literature, we had the fluorescence sensing experiment of Fe3+ with good effect on quenching. The crystals samples of 1(2 mg) were firstly introduced into 2 mL aqueous solvents, obtained suspension, then ultrasounded for half an hour. Next, gradual added the Fe(NO3)3 1.0×10-2mol·L-1(M), tested the luminescent intensities. As depicted in Fig.6A, the fluorescence intensity of 1@ Fe3+ stable suspension are quenched gradually

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decreasing with the concentration of Fe3+ increasing. The quenching efficiency is 88.37% when the Fe3+ content are rising to 0.3750 mM. Quantitatively, the quenching effect can be treated with the Stern-Volmer equation, I0/I=Ksv[M]+1 (I0 and I are the luminescence intensities of the

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compound 1 before and after addition of the analyte, respectively. Ksv is the quenching constant, [M] is the molar concentration of the Fe3+). As shown in Fig. 6B, Stern-Volmer plots for Fe3+ exhibits a good linear correlations at low concentrations (0.0148-0.0909mM), the KSV is calculated to be 3572 M-1 for 1. The mechanism of Fe3+ cations fluorescence quenching is that the interaction between metal ions and compound to produce ligand molecules to metal ions charge transfer, resulting in ligand absorption of the excitation energy is dissipated in a non-radiative form, eventually leading to fluorescence quenching of compound.

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2000 -1

1.35

1000 750

0.0244 0.0654 0.1031 0.1379 0.0833 0.2188 0.2593 0.2908 0.3197 0.3506

8

1.30 1.25

7

1.20

3

KSV= 3.5721×10 R =0.9677

1.15

6

1.10 1.05

5 4

1.00 0.95 0.00

2

250

1 0

0 390

420

450

480

510

540

570

0.02

0.04

3+

0.06

0.08

-1

0.10

Fe Concentration/(mmol•L )

3

500

360

(B)

2

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1250

0.0148 0.0566 0.0909 0.1266 0.1597 0.2000 0.2481 0.2806 0.3103 0.3421

I0/I

0 0.0431 0.0783 0.1150 0.1489 0.1803 0.2308 0.2701 0.3007 0.3333

I0/I

3+

Fe conc.(mmol⋅L )

1500

Intensity(a.u)

1.40

9

(A) 1750

0.00 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32 0.36 0.40

600

3+

wavelength(nm)

-1

Concentration/(mmol⋅L )

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Fe

Fig.6 Stern Volmer plot of compound1 with 1 mM Fe3+ solution(A)and(B)

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7. Electrochemical properties

In order to study the redox properties of the Co(II) compound, the 2 bulk-modified carbon paste electrode (2-CPE) is fabricated as the working electrodes due to insolubility in water and common organic solvents. The cyclic voltammograms of the 2-CPE in 1 mol·L-1H2SO4 solution are recorded in Fig.7A. It can be seen clearly that in the potential range of +100 to +1100 mV observe a redox peaks, Epa=0.696V, Epc=0.440V, the mean peak potential E1/2=(Epa1+Epc1)/2 is +568 mV for 2(30 mV/s), ΔEP=Epa-Epc is +256 mV for 2, which could be

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attributed to the redox of Co(III)/Co(II). Scan rates effect on the electrochemical behavior of the 2-CPE were investigated in 1 mol·L-1H2SO4 solution. As shown in Fig.7B, with the scan rates varied from 30 to 90 mV/s, the anodic peak potentials shifted toward the positive direction and the corresponding cathodic peak potentials moved to the negative direction. And the peak currents are proportional to square root of the scan rates inset of Fig.7B,

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ipa=3.14948×10-5+3.09142×10-5 V1/2, ipc=-2.37184×10-5-2.05184 ×10-5 V1/2. It indicated that the redox of Co(II) ion of compound 2 is controlled by diffusion process.

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60

(A)

20

0

4.0x10

-5

3.0x10

-5

2.0x10

-5

1.0x10

-5

I/A

90 60 30

I/µA

40

I/uA

120

0.0

-1.0x10

-5

-2.0x10

-5

-3.0x10

-5

(B)

1/2 ipa=3.14948E-5+3.09142E-5*V 2 R =0.78995 Ipa Ipc

ipc= -2.37184E-5-2.05184E-5*V1/2 R2=0.82738

0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30 0.32 1/2

V

0

-20

30mV/s 50mV/s 70mV/s 90mV/s

-30

-40 -60

-60

-90

0.0

0.2

0.4

0.6

Potential/V

0.8

1.0

1.2

0.0

0.2

0.4

0.6

Potential/V

0.8

1.0

1.2

ACCEPTED MANUSCRIPT Fig.7 CV of 2-CPE in 1M H2SO4 solution at 30 mV/s (A) and various scan rates (ranging from 30 to 90 mV/s) (B)

8.Conclusions Two new novel CPs, [Zn(HBCPBA)(tpim)]·H2O (1) and [Co(HBCPBA)(tpim)] (2) are preparedbased

on

H3BCPBA

and

tpim

ligand

via

Zn(II)/Co(II)

ions

under

hydrothermal/solvothermal conditions. Their structures were characterized by elemental

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analysis, IR spectra and X-raysingle-crystal diffraction. The results showed that the compound 1 crystallizes in the monoclinic system, P21/c space group, displays a 2D network structure, and the compound 2 crystallizes in the orthorhombic system, Pbca space group, also exhibits a 2D network structure, which has a 0D ring structure linked Co(II) ion by N-containing ligand tpim. The TGA analyses shown that the 1 and 2 have good thermal ion, and 2 shows good electrochemical reversibility. Notes

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The authors declare no competing financial interest.

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stability before 400 °C. Furthermore, 1 can be used as a fluorescent probe for detecting Fe3+

Acknowledgements: The authors gratefully acknowledge the financial supported by the Science and Technology Development Planning of Jilin Province, China (No. 20170101098JC) and The 13th Five Science and Technology Research of Jilin ProvinceDepartment of Education (No. JJKH20181174KJ) and Graduate Education Innovation Fund project of Changchun Normal University(No. cscxy2018002).

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Appendix A. Supplementary material

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References

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CCDC1868085. 1868086contain the supplementary crystallographic data for complexes 1-2 respectively. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via WWW.ccdc.cam.ac.uk/data_request/cif. Supplementary data associated with this article can be found, in the online version, at http:

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[16] (a)X. Zhang, L. Fan, W. Zhang, W. Fan, L. Sun, X. Zhao.CrystEngComm.15 (2013)4910; (b)S.J. Bora, R. Paul, M. Nandi, P. K. Bhattacharyya.J. SolidStateChem. 256 (2017)38.

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[17] L. Huo, J. Zhang, L. Gao, X. Wang, L. Fan, K. Fang, T. Hu.J. SolidStateChem.256 (2017)168. [18] T. Shi, Y.G. Chen, X.Y. Ren.New J. Chem. 41 (2017) 11215.

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[19]J. H. Cui, Y. Z. Li, Z. J.Guo, H. G. Zheng.Cryst.Growth Des.12 (2012) 3610.

ACCEPTED MANUSCRIPT Highlights

1. The 3,5-Bis (4-carboxy-phenoxy) benzoic acid (H3BCPBA) has flexible backbone and unique length.

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2. The fluorescence of Zn (II) complexe was detected for Fe3+ ions, the

voltammograms.

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M AN U

2. The Graphical Abstract

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electrochemical behavior of Co (II) complexe was studied by cyclic