Synthesis, structure, Hirshfeld surface analysis and catecholase activity of Ni(II) complex with sterically constrained phenol based ligand

Journal Pre-proof Synthesis, structure, Hirshfeld surface analysis and catecholase activity of Ni(II) complex with sterically constrained phenol based ligand Bikramaditya Mandal, Mithun Chandra Majee, Debdas Mandal, Rakesh Ganguly PII:

S0022-2860(19)31449-8

DOI:

https://doi.org/10.1016/j.molstruc.2019.127340

Reference:

MOLSTR 127340

To appear in:

Journal of Molecular Structure

Received Date: 10 July 2019 Revised Date:

25 October 2019

Accepted Date: 31 October 2019

Please cite this article as: B. Mandal, M.C. Majee, D. Mandal, R. Ganguly, Synthesis, structure, Hirshfeld surface analysis and catecholase activity of Ni(II) complex with sterically constrained phenol based ligand, Journal of Molecular Structure (2019), doi: https://doi.org/10.1016/j.molstruc.2019.127340. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier B.V.

Synthesis, structure, Hirshfeld surface analysis and catecholase activity of Ni(II) complex with sterically constrained phenol based ligand Bikramaditya Mandala, Mithun Chandra Majeeb, Debdas Mandala*, Rakesh Gangulyc* a

Department of Chemistry, Sidho-Kanho-Birsha University, Purulia - 723104, West Bengal, India. b

Department of Inorganic Chemistry, Indian association for the cultivation of science, Kolkata – 700032, India.

c

CBC, SPMS, 21 Nanyang Link, Nanyang Technological University, Singapore 637371

Abstract A mononuclear square planer Ni(II) complex [NiIIL] (1) with sterically encumbered phenol based tetra dentate N2O2 ligand has been synthesized. Several spectroscopic tools have been employed to characterize this complex. The crystal structure of this Ni(II) complex obtained from single crystal X-ray diffraction study reveals that the central metal ion adopts a square planar environment and crystalized in monoclinic space group C 2/c with a =24.1784(10), b = 9.3537(4) and c = 8.3326(4) with β = 97.0690(11). The Hirshfeld surface analysis shows halogen-halogen interaction. The Ni(II) complex has been found to be an effective catalyst for the aerial oxidation of 3,5-DTBC to 3,5- DTBQ

in methanol. For kinetic study,

Michaelis-Menten model has been approached to determine the Kcat, KM and Vmax. The kinetic studies confirm that the turnover number (TON) of complex 1 is 1.762 × 103 h-1.

Keywords: Syntheses. Characterization. X-ray structure . Hirshfeld analysis. Catecholase activity

Introduction The importance of coordination compounds of nickel (II) with phenol-based ligands for their potential applications as catalysts in olefin polymerization has led to extensive research of such complexes with anionic (O, N) chelating ligands involving phenolate donor(s). Grubbs and co-workers are the first to introduce salicylaldimine derivatives with increasing steric bulk as ligands to develop new generation of nickel catalysts, capable of initiating olefin polymerization even in water [1]. Many more have since been introduced in ethylene chemistry, showing efficient control over the polymerization process [2]. In addition to it, the nickel(II)-phenolate chemistry is also quite interesting specially under oxidative conditions where the oxidation might occur at the metal centre, generating Ni(III) state or on the ligand with concomitant formation of phenoxyl radical which plays significant role in biological oxidation [3]. Catechol oxidase is a member of type III copper proteins which readily oxidizes odiphenols to produce subsequent o-quinones as reactive intermediate species. The generated o-quinones are auto polymerized forming a brown polyphenolic pigment, i.e., melanin, a process which is considered to protect damage tissues against pathogens or insects [4]. The X-ray crystallographic structure of catechol oxidase isolated from sweet potatoes was reported in 1998 [5]. The active centre of the met-form of this native enzyme consists of a hydroxo-bridged di-copper (II) centre in which each copper (II) centre is coordinated to three histidine nitrogen and assumes a trigonal pyramidal geometry with one nitrogen at the apical position. The ability of di-copper complexes to oxidize phenols and catechol is well established by various research group. A large number of copper, manganese, iron, cobalt and zinc complexes have been reported which shows catecholase activity [6]. Recently, a few mononuclear and multinuclear nickel complexes have been reported to display catecholase activity [7]. Inspired from the above knowledge, we synthesize mononuclear square planar Ni(II) complex with phenol based N2O2 chelating agent. X- ray crystallography, and various spectroscopic analysis have been carried out to characterize this complex. Furthermore, the nickel complex 1 is found to be an effective functional model of the catechol oxidase enzyme as it catalyzes the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tertbutylbenzoquinone (3,5-DTBQ) with molecular oxygen in methanol at 25°C. Hirshfeld surface analysis shows Cl-Cl interactions along with hydrogen bonding.

Experimental Materials Piperazine, 2,4-dichlorophenol and 3,5-DTBC were purchased from Aldrich. All solvents used were of reagent grade and purified with suitable drying agents and distilled under nitrogen before use [8]. Remaining chemicals were used as received without further purification. Synthesis of 2-((4-(3,5-dichloro-2-hydroxybenzyl)piperazin-1-yl)methyl)-4,6dichlorophenol (H2L) 10 mmol (0.86 g) piperazine was taken in 25 mL methanol in a R.B flask. To this methanolic solution, 20 mmol (0.60g) paraformaldehyde was added. The resulting mixture was refluxed for 3 hrs. Then the solution was cooled and 10 mmol (3.2g) of 2,4dichlorophenol was added to it. The mixture was refluxed for further 12 hrs. A white solid precipitate was obtained and it was filtered. The white precipitate was washed with ethanol for several times and then kept in desiccator. The product was recrystallized from a mixture of acetone - pet ether mixture at room temperature. Yield : 3.5g (80%.) Anal. Calcd. For C18H18Cl4N2O2: C, 49.54; H, 4.12; N, 6.42 Found: C, 49.12; H, 4.01; N, 6. 24 . IR (KBr disk, cm-1): 3454, 2836, 1637, 1470, 1457, 1380, 1312, 1168, 1005, 871. 1H NMR (300 MHz, CDCl3, 25°C), δ/ppm: 2.16 (s, 8H, CH2-CH2), 3.71 (s, 4H, benzylic), 5.29 (s, 2H, ph-OH), 6.89 (s, 2H, aryl), 7.26 (s, 2H, aryl).

Scheme 1 Schematic presentation of preparation of ligand

Synthesis of [NiIIL] (1) 0.5 mmol (0.22 g) H2L was dissolved in 25 mL methanol. 1.0 mmol (0.04g) NaOH was added and the mixture was refluxed for 30 minute. The resulting solution was cooled and

0.5 mmol (0.150 g) Ni(NO3)2.6H2O was added and refluxed for another 1 hour. Red colour precipitated was obtained and it was filtered. Diffraction quality crystals were obtained by diffusing methanol into a dichloromethane solution of the compound. Yeild: 0.14g (60 %). Anal. Calcd. For C18H16Cl4N2NiO2: C, 43.82; H, 3.25; N, 5.69 Found: C, 43.12; H, 3.09; N, 5.12. IR (KBr disk, cm-1): 2994, 2922, 2869, 1450, 1430, 1326, 1311, 1289, 1175, 1114, 861, 752, 514. UV-vis (CH2Cl2), λmax/nm (εmax/mol-1cm2): 511 (84), 356 (271).

X-ray crystallography Diffraction quality crystals of 1 were grown at room temperature by diffusing methanol into a dichloromethane solution of the compound while crystals of H2L were grown by diffusion hexane into a acetone solution of the compound. Intensity data for the crystals were measured on a Bruker SMART 1000 CCD diffractometer using a graphite monochromated Mo Kα radiation (λ = 0.71073 Å) at 100 K. Intensity data for H2L and 1 were collected with θmax of 28.38̊ and 28.34̊ deg, respectively. No crystal decay was observed during the data collections. Relevant crystal data and refinement details are given in Table 1. The structures were solved by direct methods [9] and refined on F2 by a full-matrix leastsquares procedure using the program SHELXL 97 [10]. Structural and refinement parameters are given in Table 1. Bond lengths, angles and atomic displacement parameters are given in the supplementary information.

Table 1 Summary of the Crystallographic Data for the Complex 1.

Empirical formula

C18H18Cl4N2O2, H2L

C18H16Cl4N2NiO2, 1

Formula weight

436.14

492.84

T (K)

100

100

λ (Mo Kα), Å

0.71073

0.71073

Space group

P 21/c

C 2/c

Crystal system

Monoclinic

Monoclinic

a (Å)

7.4610(8)

24.1784(10)

b (Å)

17.0977(18)

9.3537(4)

c (Å)

7.7721(9)

8.3326(4)

V (Å3)

924.09(18)

1870.16

Z

2

4

DCalcd. (g cm-3)

1.567

1.75

µ(mm-1)

0.657

1.626

F (000)

448

1000

θ ranges (º)

2.93 - 28.38

2.33 - 28.34

-9<=h<=9, -22<=k<=22, -10<=l<=10

-31≤ h ≤ 31 -12 ≤ k ≤ 12 -10 ≤ l ≤ 10

Reflections collected

12353

2341

Rint

0.0855

0.0423

Goodness of fit

1.118

1.196

No. of parameters

119

123

0.0787, 0.1405

0.0497, 0.1322

0.673, -0.583

1.192, -1.247

Index ranges

a

b

R1 (Fo), wR2 (Fo) (all data) Largest diff. peak, deepest hole (eÅ-3) a

R = ∑||Fo| - |Fc||/∑|Fo|. bwR = [∑[w((Fo2 - Fc2)2]/∑w(Fo2)2]

Catalytic oxidation of 3,5-DTBC The catecholase activity of complex 1 was observed by taking most suitable substrate

3,5-ditert-butylcatechol (3,5-DTBC) in a methanol

solution under aerobic

conditions at room temperature [11]. Complex 1 in methanol solvent (10-4 M concentration) was added with 100 equiv. of 3,5-ditert-butylcatechol (3,5-DTBC) under aerobic conditions at room temperature in order to check the catecholase activity of the complex. The reaction was monitored spectrophotometrically by the increase in the maximum absorbance of the quinone band around 400 nm as a function of time [12]. Absorbance vs. wavelength of the solution was plotted at a regular time intervals of 5 min. A blank experiment without catalyst does not show formation of the quinone up to 6 h in MeOH. To check the dependence of rate on substrate concentration and upon various kinetic parameters, 1.75 x 10–4 M solution of complex 1 was added with increasing amounts of 3,5DTBC from 1.4 x 10-3 M to 5 x 10-3 M. In each case, the reaction was spectrophotometrically followed by observing the increase in the absorbance at 400 nm for up to 6 hr. The rate constant vs substrate concentration data was then analyzed on the basis of the Michaelis– Menten approach of enzymatic kinetics to get the Lineweaver–Burk plot as well as the values of the parameters Vmax, KM, and Kcat.

Results and discussion Syntheses The tetra dentate ligand 2-((4-(3,5-dichloro-2-hydroxybenzyl)piperazin-1-yl)methyl)-4,6dichlorophenol (H2L) was synthesized via Mannich reaction between 2,4-dichlorophenol, Piperazine, and formaldehyde. The synthetic procedure is depicted in Scheme 1. Ligand is characterized by 1H NMR spectroscopy as well as other spectroscopic tools and the 1H NMR spectrum of H2L is displayed in Figure S1 in the Supporting Information. The NMR spectra show characteristic peak of the various protons of different chemical environment as depicted in the experimental section. The mononuclear square planar Ni(II) complex have been

synthesized by reacting Ni(NO3)2.6H2O with a tetradentate phenol based N2O2 ligand (H2L) in methanol. The strategy adopted here is shown in Scheme 2. Compound [NiL] 1 has a very interesting mononuclear square planar structure containing the tetradentate ligand with N, O donor site as revealed from X-ray crystallography (see later).Here the piperazenyl moiety of the ligand resides in comparatively less stable boat form in order to coordinate with metal centre via two imine nitrogen and two phenol oxygen atom. The compound was characterized using various spectroscopic tools. The complex was initially characterized by IR spectroscopy. IR spectra of this complex show all the characteristic bands of the coordinated L2- ligand. FT-IR spectra has shown a prominent band appears at 1289 cm-1due to υ(co/phenolate) stretching vibrations [13- 14]. Magnetic measurement of the complex suggests that the complex is diamagnetic in nature.

Scheme 2 Schematic presentation of preparation of complex 1

Description of crystal structure The molecular structure of the free ligand, H2L is depicted in Fig 1a. The ligand crystallizes in the monoclinic system P 21/c. The piperazine moiety assumes the stable chair form to minimize the steric interaction between the bulky dichlorophenol moieties. The molecular structure of complex 1 is depicted in Fig. 1b. The complex crystallizes in monoclinic space group C 2/c. The Ni(II) centre in this mononuclear complex is fourcoordinated using a doubly deprotonated tetradentate ligand L2-, providing O(1), N(1), N(2) and O(2) donor sites. The Ni-N bond distance (1.912Å) and Ni-O bond distance (1.852Å) are found to be in reported ranges [15]. The observed cis bond angles N1-Ni1-O1(96.5̊), O1-Ni1O1 (89.9̊) and trans bond angle N1-Ni1-O1 (173.5̊) are closer to an ideal square planar environment. A greater deviation from 90 degree is observed for N1-Ni1-N1 (77.2°) caused by the chelated boat conformation of piperazinyl moiety.

When viewed along b-axis the Cl-Cl interactions forms a zig-zag pattern along the caxis as shown in Fig 2a. Viewing along the c-axis exhibits the 2-D network formed by the ClCl interactions as shown in Fig 2b.

Fig. 1a: Molecular structure of the ligand, H2L

Fig. 1b: Molecular structure of complex 1 (H-atoms are removed for clarity)

Fig. 2a: Viewed along b-axis (Cl-Cl interactions are shown by the light blue lines)

Fig. 2b: Viewed along c-axis (Cl-Cl interactions are shown by the light blue lines)

Hirshfeld Surface Analysis Hirshfeld surface analysis was performed using Crystal Explorer [16]. The Hirshfeld surface was mapped using an iso value of 0.5 with red contours indicating a contact less than the sum of the Van Der Waals radii of the respective elements while blue and white contours indicate that the nearest external atom is at a distance greater than or equal to the sum of the Van Der Waals radii respectively from the atomic co-ordinate. The Hirshfeld analysis reveals a short contact between O1 and H8B of a neighbouring molecule of 2.796 Å, demonstrated by red contours on the Hirshfeld surface at these atoms (Fig. 3).

Fig. 3: dnorm surface for 1 The fingerprint plots show that the predominant intermolecular interaction is Cl–H interactions; these account for 44.4% of the Hirshfeld surface (Fig. 4a). O-H interaction account for 9.8% (Fig. 4b) while Cl-Cl interaction account for 6.1% (Fig. 4c) of the Hirsfeld surface These interactions are presumed to be primarily the result of attractive dispersion forces [17].

Fig. 4a

Fig. 4b

Fig. 4c

Cl-Cl interactions are of two types [18], type I is θ1 ≈ θ2 (where θ1 is the angle C–Cl1···Cl2 and θ2 is the angle C–Cl2···Cl1) and type II is characterized by θ1 ≈ 90° and θ2 ≈ 180°. In the case of 1, though there two different Cl-Cl interactions but both exhibit type I interaction with θ1 ≈ 147° and θ2 ≈ 97° (set 1), with the two adjacent Cl atoms are at 3.533 Å, and θ1 ≈ 125° and θ2 ≈ 85° (set 2), with the two adjacent Cl atoms are at 3.649 Å. Such interactions exists as a result of close packing that serves to minimize repulsion between adjacent Cl atoms [19].

Electronic Spectra The electronic spectra of the complex 1 have been measured in CH2Cl2 solution and the data are presented in experimental section. Spectrum of 1 in the visible region displays two medium intensity bands at 511 and 364 nm in dichloromethane solution (Fig. 5) due to spin-allowed 1A1g→ 1A2g and 1A1g→ 1B1g transitions, respectively as expected for a square planar d8 system [20]. Remaining band maxima appearing around at UV region are due to ligand internal transition.

Fig. 5: Electronic absorption spectrum of complex 1 in DCM (1x 10-4 M)

Catecholase activity The catecholase activity of mononuclear nickel complex [NiIIL] (1) was observed by taking 3,5-ditert-butyl catechol (3,5-DTBC) as a model substrate in methanol under aerobic condition at room temperature.

When 3,5- ditert-butyl catechol

was added to the

methanolic solution of the complex in presence of air, there was a gradual increase in absorbance at 400 nm as shown in Fig. 6 characteristic to the formation of 3,5-di-tert-butyl benzoquinone. 3,5-ditert-butylcatechol (3,5 - DTBC) has been selected as the substrate as it

can readily be oxidised to 3,5-ditert-butyl benzoquinone (3,5 - DTBQ). Kinetic experiments were carried out spectrophotometrically with complex 1 and the substrate 3,5-DTBC in methanol at 25°C. The conversion of 3,5–DTBC to 3,5-DTBQ (Quinone band maxima) was monitored with time at a wave length of 400 nm for [NiIIL] (1) in methanol. The rate constant for a particular complex–substrate concentration ratio

was calculated

by change in

absorbance versus time plot by choosing initial rate method. The substrate concentration dependence of the oxidation rate was noticed under aerobic conditions taking 1.75 x 10–4 M solution of complex 1 and increasing amounts of 3,5DTBC from 1.4 x 10-3 M to 5 x 10-3 M in methanol. The calculated rate constants versus substrate concentrations results were, then, plotted in Fig. 7. The rate constant versus substrate concentration data were explained on the basis of the Michaelis–Menten approach of enzymatic kinetics to get the Line weaver–Burk plot as well as the values of the parameters Vmax, KM, and Kcat (Table 2). Table 3 shows the catalytic activities of some nickel compounds.

It is worth

mentioning that our nickel compound exhibits quite high TON (Kcat = 1.762× 103 h-1) for the catalytic oxidation of 3,5 DTBC to 3,5 DTBQ in comparison with other nickel compounds [7f, 21 -25].

. Fig. 6: Increase of quinone band recorded against 5 minutes time intervals at around 402 nm after addition of 100 equivalents of 3,5-DTBC to a methanolic solution containing [NiIIL] (0.81× 10-3 M) at 25 °C.

Table 2: Kinetic parameters from Lineweaver-Burk plot.

Solvent

Vmax (M min-1)

Std. error

KM (M)

Std. error

kcat (h-1)

MeOH

2.0 × 10-2

15.97 × 10-2

2.03 × 10-3

2.38 × 10-3

1.762 × 103

Fig. 7: Plot of rate vs. [substrate] in the presence of [NiIIL] 1 in MeOH; inset: Lineweaver– Burk plot.

Table 3 Comparison of Kcat value for the oxidation of 3,5-DTBC to 3,5-DTBQ by different

Complex

Solvent

Vmax(M min-1)

[NiL]

MeOH

2.0 × 10-2

KM (M)

Kcat (h-1)

Ref.

2.03 × 10-3

1.762× 103

Present work

[Ni2(HL1)4(H2O)]

MeOH

5.19 × 10-4

6.05 × 10-3

1.87 × 104

21

[Ni2(HL2)4(H2O)]

MeOH

4.97 × 10-4

8.14 × 10-3

1.79 × 104

21

[Ni2(HL3)4(H2O)]

MeOH

3.86 × 10-4

5.78 × 10-3

1.38 × 104

21

[Ni(L4)(H2O)3](NO3)2

MeOH

1.46 × 10-5

1.92 × 10-3

5.26 × 101

22

[Ni(L5)(H2O)3](NO3)2

MeOH

3.57 × 10-5

4.24 × 10-5

1.29 × 102

22

Nickel complexes

[Ni2(L6)2(NCS)2]

CAN

10.7 × 10-5

7.2 × 10-3

6.41 × 101

23

[Ni2(L7)2(NCS)2]

CAN

8.5 × 10-5

7.8 × 10-3

5.11 × 101

23

[Ni2(L8)2(NCS)2]

CAN

13.6 × 10-5

8.1 × 10-3

81.7 × 101

23

[Ni(L9)]ClO4

MeOH

2.67 × 10-2

8.33 × 10-2

8.0 × 103

24

[Ni(L10)]ClO4

MeOH

4.55 × 10-3

1.58 × 10-3

2.7 × 103

24

[Ni2(L11)(NO3)(H2O)3]NO3

MeOH

4.42 × 10-5

2.00 × 10-3

1.5 × 103

25

[Ni3(L12)2(OAc)2]

MeOH

1.07 × 10-3

4.79 × 10-3

3.85 × 103

7 (f)

H2L1 = 1:1 condensation of 5-amino-1- pentanol and salicylaldehyde, H2L2 = 1:1 condensation of 5-amino-1- pentanol and 5-bromo salicylaldehyde, H2L3 = 1:1 condensation of 5-amino-1- pentanol and 3-methoxy salicylaldehyde, H2L4 = condensation product between 2-benzoylpyridine and N-(2-aminoethyl)pyrrolidine, H2L5 = condensation product between

5-chlorosalicylaldehyde

and

N-(2-aminoethyl)piperazine,

[1-(3-methylamino-propylamino)-ethyl]-phenol,

H2L7

=

2-[1-(2-

H2L6

=

2-

dimethylamino-ethyl

amino)-ethyl]-phenol, H2L8 = 2-[1-(3-dimethylamino-propylamino)-ethyl]-phenol,L9=1phenyl-3-((2-(piperidin-4-yl)ethyl)imino)but-1-en-1-ol,

L10

=

4-((2-(piperazin-1-

yl)ethyl)imino)pent-2-en-2-ol, H2L11 = 1:2 condensation of 1,3-diaminopropane and 2,6diformyl-4-tert-butylphenol, H2L12 = N,N-(salicyaldene)-1,3-diaminopropan-2-ol.

Plausible Mechanism A plausible mechanism for the aerobic oxidation of 3, 5-DTBC to 3, 5-DTBQ catalysed by complex 1 is depicted in the scheme 3. We propose that the present compound 1 catalyzes the oxidation of 3,5-DTBC to 3,5-DTBQ through the reduction of Ni(II) to Ni(I) where an organic radical intermediate such as Ni(I)-semiquinonate species might be formed. In the first step of the catalytic cycle, nickel complex 1 binds with the substrate molecule to produce species 1a. Subsequently, the reaction proceeds through the formation of a Ni(I)semiquinonate radical intermediate 1b. The catalytic cycle is completed by the reaction of Ni(I) - semiquinone species with di-oxygen leading to the re-oxidation of Ni(I) to Ni(II) and reduction of di-oxygen. Quinone molecule is produced as the product and hydrogen peroxide as a by-product. To detect the formation of hydrogen peroxide during the catalytic reaction we used the modified iodometric method as reported in previous paper [26]. Nickel (II) compound gives positive result for the formation of H2O2 as the end product by observing the

characteristic peak of 353 nm for I3¯ ions generated by the reaction of the peroxide with potassium iodide (Fig. S2). The estimation of H2O2 suggest that after 1 h of oxidation nearly 80 % H2O2 is formed with respect to the production of 3,5-DTBQ. The estimation of H2O2 assumes that nearly 1 mol of H2O2 was shown to be produced per mole of 3,5 DTBC along with 1 mol of 3,5 DTBQ. Such incident clearly indicates that in the catalytic cycle two electron reduction of molecular oxygen is occurred as reported earlier [27]. Electrochemical behaviour of the mixture of the complex 1 and 3,5 DTBC has been studied by cyclic voltammetry (CV) in methanol solution (0.1M TEAP) versus Ag/AgCl reference. The electrochemical studies exhibits one reductive response at E1/2 = - 0.507 V ( Fig. S3) and we believe the reversible response is due to a Ni(II)/Ni(I) reduction [21,28]. The reductive response exhibited by the nickel (II) complex at E1/2 responsible for the oxidation of 3,5- DTBC.

= - 0.507 V is supposed to be

Scheme3: A plausible mechanistic pathways for the aerobic catechol oxidation catalyzed by complex 1.

Conclusion In summary, we have prepared a square planar nickel (II) complex with a sterically constrained phenol based ligand with N2O2 donor site. Structure of this compound is characterized by X-ray single crystal diffractometer. The Ni(II) centre in this mononuclear complex is four-coordinated using a doubly deprotonated tetradentate ligand. The piperazenyl moiety of the ligand occupies in comparatively less stable boat form in order to coordinate with metal centre. The Hirshfeld surface analysis indicates halogen-halogen interaction. In addition,

the copper complex 1 efficiently catalyses the oxidation of 3,5 DTBC to 3,5 DTBQ in presence of air. The turnover number of this reaction is 1.762 × 103 h-1. Supplementary data CCDC 1892016 and CCDC 1955816 contains the supplementary crystallographic data for compound 1 and H2L, respectively. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223-336-033; or e-mail: deposit@ ccdc.cam.ac.uk.

Acknowledgment Financial support received from Department of Science and Technology, Government of West Bengal, Kolkata (Project memo no. 1071(Sanc)/ST/P/S&T/15G-4/2015 dated 23.02.2016) is gratefully acknowledged. We are grateful for the instrumental support from Department of Inorganic Chemistry, Indian Association for the Cultivation of Science.

References 1. (a) C. Wang, S. Friedrich, T.R. Younkin, R.T. Li, R.H. Grubbs, D.A. Bansleben, M.W. Day, Organometallics17(1998) 3149-3151; (b) T.R. Younkin, E.F. Connor, J.I. Henderson, S.K. Friedrich, R.H. Grubbs, D.A. Bansleben,Science287(2000) 460-462; (c) Z. Wang, Q. Liu, G.A. Solanad, W.-H. Sun, Coord. Chem. Rev. 350 (2017) 68-83; (d) L. Zhong, G. Li, G. Liang, H. Gao, Q. Wu, Macromolecules 50 (2017) 2675-2682; (f) D. Zhang, C. Chen, Angewandte Chemie 56 (2017) 1467214676. 2. (a) F. Speiser, P. Braunstein, Inorg. Chem. 43 (2004) 4234-4240; (b) D. Zhang, G.X. Jin, N. Hu, J. Chem. Soc. Chem. Commun. (2002) 574-575. 3. (a) J.W. Whittaker, Met. Ions Biol. Syst. 30 (1994) 315-360; (b) J. Stubbe, W.A. Van der Donk, Chem. Rev. 98 (1998) 705-762; (c) P. Chaudhuri, K. Wieghardt, Prog. Inorg. Chem. 50 (2001) 151; (d) Y. Shimazaki, S. Huth, S. Karasawa, S. Hirota, Y. Naruta, O. Yamauchi, Inorg. Chem. 43 (2004) 7816-7822; (e) T. Glaser, M. Heidemeier, R. Frohlich, P. Hildebrandt, E. Bothe, E. Bill, Inorg. Chem. 44 (2005) 5467-5482. 4. (a) E.I. Solomon, U.M. Sundaram, T.E. Machonkin, Chem. Rev. 96(1996) 25632606; (b) C. Gerdemann, C. Eicken, B. Krebs, Acc. Chem. Res. 35(2002) 183-191.

5. T.K. labunde, C. Eicken, J.C. Sacchettini, B. Krebs, Nat. Struct. Biol. 5 (1998) 1084-1090. 6. (a) A. Martinez, I. Membrillo, V.M. Ugalde-Saldivar, L. Gasque, J. Phys. Chem. B 116 (2012) 8038-8044; (b) A. Dutta, S. Biswas, M. Dolai, B.K. Shaw, A. Mondal, S.K. Sahab, M. Ali, RSC Adv. 5 (2015) 23855-23864; (c) P. Chakraborty, S. Majumder, A. Jana, S. Mohanta, Inorg. Chim. Acta 410 (2014) 65-75; (d) P. Chakraborty, S. Mohanta, Inorg.Chim. Acta 435(2015) 38-45; (e) A. Hazari, L.K. Das, R.M. Kadam, A. Bauzá, A. Frontera, A. Ghosh, Dalton Trans. 44(2015)38623876; (f) S. Adhikari, A. Banerjee, S. Nandi, M. Fondo, J.S. Matalobos, D. Das, RSC Adv. 5 (2015) 10987-10993; (g) S.K. Dey, A. Mukherjee, New J. Chem. 38 (2014) 4985-4995; (h) R. Modak, Y. Sikdar, S. Mandal, S. Chatterjee, A. Bienko, J. Mrozoniski, S. Goswami, Inorg. Chim. Acta 416 (2014) 122; (i) M. Mitra, A.K. Maji, B.K. Ghosh, P. Raghavaiah, J. Ribas, R. Ghosh, Polyhedron 67(2014) 19-26; (j) M. Sheoran, K. Bhar, S. Jain, M. Rana, T. A. Khan, A. K. Sharma, Polyhedron 161 (2019) 169-178; (j) A. Zengin, K. Karaoğlu, M. Emirik, E. Menteşe, K. Serbest, J. Mol. Structure 1193 (2019) 444-449; (k) T. Basak, K. Ghosh, S. Chattopadhyay, Polyhedron 146 (2018) 81-92; (l) S. Roy, S.K. Sarkar, R. Saha, T.K. Mondal, C. Sinha, Inorg. Chimica Acta, 482 (2018) 659-668; (m) B. Mandal, M.C. Majee, T. Rakshit, S. Banerjee, P. Mitra, D. Mandal, J. Mol. Structure, 1193 (2019) 265-273; (n) D. Mondal, S. Kundu, M.C. Majee, A. Rana, A. Endo, M. Chaudhury, Inorg. Chem. 56 (2017) 9448; (o) D. Mondal, M.C. Majee, Inorg. Chim. Acta. 465 (2017). 7. (a) J. Adhikary, P. Chakraborty, S. Das, T. Chattopadhyay, A. Bauzá, S.K. Chattopadhyay, B. Ghosh, F.A. Mautner, A. Frontera, D. Das, Inorg. Chem. 52 (2013) 13442-13452; (b) A. Guha, K.S. Banu, S. Das, T. Chattopadhyay, R. Sanyal, E. Zangrando, D. Das, Polyhedron 52(2013) 669-678; (c) T. Chattopadhyay, M. Mukherjee, A. Mondal, P. Maiti, A. Banerjee, K.S. Banu, S. Bhattacharya, B. Roy, D.J. Chattopadhyay, T.K. Mondal, M. Nethaji, E. Zangrando, D. Das, Inorg. Chem. 49 (2010) 3121-3129; (d) A. Biswas, L.K. Das, M.G.B. Drew, G. Aromí, P. Gamez, A. Ghosh, Inorg. Chem. 51 (2012) 7993-8001; (e) L.K. Das, A. Biswas, J.S. Kinyon, N.S. Dalal, H. Zhou, A. Ghosh, Inorg. Chem. 52 (2013) 11744-11757; (f) A. Pal, S.C. Kumar, A. K. Ghosh, C.-H. Lin, E. Riviere, T. Mallah, R. Ghosh, Polyhedron 110 (2016) 221- 226.

8. D.D. Perrin, W.L.F. Armarego, D.R. Perrin, Purification of Laboratory Chemicals, Peragamon, Oxford, (1980) 2ndedn. 9. G.M. Sheldrick, SHELX 97, Release 97-1, Program for the Refinement of Crystal Structure, (1997) University of Gottingen, Germany. 10. G.M. Sheldrick, SHELXS 97, Acta Cryst, 46 (1990) 467. 11. J. Mukherjee, R. Mukherjee, Inorg. Chim. Acta. 337 (2002) 429-438. 12. F. Zippel, F. Ahlers, R. Werner, W. Haase, H.F. Nolting, B. Krebs, Inorg. Chem. 35(1996) 3409-3419. 13. (a) D. Mandal, S.K.T. Abtab, A. Audhya, E.R.T. Tiekink, A. Endo, R. Clerac, M. Chaudhury, Polyhedron 52(2013) 355-363; (b) D. Mandal, P.B. Chatterjee, S. Bhattacharya, K.Y. Choi, R. Clerac, M. Chaudhury, Inorg. Chem, 48(2009) 18261835. 14. K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, 3rded, (1978) Wiley-Interscience, New York. 15. M. Das, R. Nasani, M. Saha, S. Mobin, S. Mukhopadhyay, Dalton Trans 44(2015) 2299-2310. 16. S.K. Wolff, D.J. Grimwood, J.J. McKinnon et al, Crystal Explorer (Version 3.1), (2012). 17. S. Rösel, H. Quanz, C. Logemann, J. Am. Chem. Soc, 139(2017) 7428–7431. 18. M. Capdevila-Cortada, J. Castelló, J.J. Novoa, Crys. Eng. Comm. 16 (2014) 82328242. 19. V.R. Pedireddi, D.S. Reddy, B.S. Goud, D.C. Rae, G.R. Desiraju, J. Chem. Sci. Perkin Trans. 2 (1994) 2353-2360 20. A.B.P. Lever, Inorganic Electronic Spectroscopy, 2nd ed., (1984) Elsevier Science; Amsterdam. 21. R. Modak, Y. Sikdar, S. Mandal, S. Chatterjee, A. Bieńko, J. Mroziński, S. Goswami, Inorg. Chim. Acta. 416 (2014) 122-134. 22. A. Guha, K.S. Banu, S. Das, T. Chattopadhyay, R. Sanyal, E. Zangrando, D. Das, Polyhedron, 52 (2013) 669-678. 23. A. Biswas, L.K. Das, M.G.B. Drew, G. Aromí, P. Gamez, A. Ghosh, Inorg. Chem. 51 (2012) 7993-8001.

24. M. Das, R. Nasani, M. Saha, S.M. Mobin, S. Mukhopadhyay, Dalton Trans. 44 (2015) 2299-2310. 25. S. Das, P. Maiti, T. Ghosh, E. Zangrando, D. Das, Inorg. Chem. Comm. 15 (2012) 266–268. 26. (a) M. Das, R. Nasani, M. Saha, S. M. Mobin, S. Mukhopadhyay, Dalton Trans. 44 (2015) 2299; (b) A. I. Vogel, A Text Book of Quantitative Inorganic Analysis, Third ed., Wiley, New York, 1961, p. 343. 27. A. Hazari, L .K. Das, R. M. Kadam, A.Bauzá, A. Frontera, A. Ghosh, Dalton Trans. 44 (2015) 3862. 28. (a) M.Y. Darensbourg, I. Font, D. K. Mills, M. Pala, J. H. Reibenspies, Inorg. Chem. 31 (1992) 4965; (b) D. C. Goodman, R. M. Buonomo, P. J. Farmer, J. H. Reibenspies, M. Y. Darensbourg, Inorg. Chem. 35 (1996) 4029.

Highlights

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A mononuclear square planer Ni(II) complex [NiIIL] was synthesized.

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The crystal structure of this Ni(II) complex was obtained from single crystal Xray diffraction study.

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Catechol oxidase activity of the complex was observed.

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Hirshfeld surface analysis was performed.

Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: