The syntheses, molecular structure analyses and DFT studies on new benzil monohydrazone based Schiff bases

Accepted Manuscript The syntheses, molecular structure analyses and DFT studies on new benzilmonohydrazone based Schiff bases Gökhan Elmacı, Halil Duyar, Burcu Aydıner, Nurgül Seferoğlu, Mir Abolfazl Naziri, Ertan Şahin, Zeynel Seferoğlu PII:

S0022-2860(18)30181-9

DOI:

10.1016/j.molstruc.2018.02.035

Reference:

MOLSTR 24857

To appear in:

Journal of Molecular Structure

Received Date: 28 November 2017 Revised Date:

2 February 2018

Accepted Date: 8 February 2018

Please cite this article as: Gö. Elmacı, H. Duyar, B. Aydıner, Nurgü. Seferoğlu, M.A. Naziri, E. Şahin, Z. Seferoğlu, The syntheses, molecular structure analyses and DFT studies on new benzilmonohydrazone based Schiff bases, Journal of Molecular Structure (2018), doi: 10.1016/j.molstruc.2018.02.035. 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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The syntheses, molecular structure analyses and DFT studies on new Benzilmonohydrazone based Schiff bases Gökhan Elmacıa, Halil Duyarb, Burcu Aydınerb, Nurgül Seferoğluc, Mir Abolfazl Nazirid,

University, Adıyaman 02040, Turkey b

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Ertan Şahind, Zeynel Seferoğlub,*Department of Chemistry, Faculty of Science, Adıyaman

Department of Chemistry, Faculty of Science, Gazi University, Teknikokullar, Ankara 06500,

Department of Advanced Technology, Gazi University, Teknikokullar, Ankara 06500, Turkey d

Department of Chemistry, Faculty of Science, Atatürk University, Erzurum 25240, Turkey

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Turkey

Abstract

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Benzilmonohydrazone based Schiff bases was synthesized and characterized by 1H NMR, 13C NMR, HRMS as well as by single crystal X-ray diffraction. The geometry of the compounds were optimized by the DFT method and the results were compared with the X-ray diffraction

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data. The HOMO and LUMO energy gap and also related parameters (electronic chemical potential (µ) and global hardness (η), global electrophilicity index (ω) and softness (s)) were

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obtained from ground state calculations. In addition, the thermal properties of the compounds were investigated by DTA–TGA. The results showed that the compounds have good thermal properties for practical applications as optic dye. Keywords: Benzil, Benzilmonohydrazone, Schiff base, X-ray, Structure analysis, Thermal characterization, DFT. *Corresponding authors Tel.: +90 312 2021525; fax: +90 312 2122279 *E-mail address: [email protected] (Z. Seferoğlu).

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ACCEPTED MANUSCRIPT 1.Introduction

Schiff's bases, which are synthesized from the condensation of primary amines with carbonyl groups such as aromatic/heteroaromatic aldehydes or ketones, are significant ligands for

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coordination chemistry. Their metal complexes have a wide range of applications in the field of pharmacy, medicine, biological systems and also exhibit high catalytic activity in oxidation, epoxidation, hydroxylation reactions [1-5]. Over the last decades, fluorophore and

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chromophore bearing many Schiff bases have been extensively studied as fluorescent light-up chemosensor for the determination of some important anions and cations such as F−, Cl−, Br−,

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I−, AcO−, CN−, Pd(II)/Pt(II) and Cu2+ [6-9]. Overall, the synthesis of new Schiff bases with varying amines and carbonyl groups has attracted great attention in the catalyst and sensor applications. In our previous work, we synthesized, characterized, and evaluated the molecular structure of a new type benzilmonohydrazone based Schiff base bearing nitro

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substituent as strong electron accepting functional group [6]. In the current study, we synthesized a new series of benzilmonohydrazone based Schiff bases having different types of electron accepting and donating groups (Scheme 1). The molecular structure analyses of the

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synthesized compounds were studied by comparing experimental X-ray diffraction and theoretical DFT calculations data. Furthermore, thermal behaviors of these compounds were

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investigated by thermogravimetric differential thermal analysis (TG-DTA).

Scheme is here

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ACCEPTED MANUSCRIPT 2. Experimental

2.1. Materials and physical measurements

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Benzilmonohydrazone based Schiff bases were synthesized according to the method reported earlier [10]. All chemicals were purchased from Aldrich and were used without further purification. All reactions were carried out in oven-dried glassware with magnetic stirring.

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Thin layer chromatography (TLC) was performed by using Merck silica gel (60 F254) plates (0.25 mm) and visualized under Ultraviolet light (UV). FT-IR (ATR) spectra were recorded

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on Perkin-Elmer Spectrum 100 FT-IR spectrophotometer. NMR spectra were recorded on a Bruker Avance 300 Ultra-Shield in DMSO-d6. Chemical shifts are expressed in δ units (ppm). The thermogravimetric analysis (TGA) were carried out with a Shimadzu DTG-60H working at a heating rate of 10 °C min−1 under a nitrogen flow (100 mL min−1). Mass spectrometry

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was performed on Waters LCT Premier XE (TOF MS). X-ray single crystal structure was

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determined on Rigaku R-axis Rapid-S IP area detector diffractometer.

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2.2. X-ray crystallography

For the crystal structure determination, single-crystal of compounds 1h, 1i, 1j and 1k was used for data collection on a four-circle Rigaku R-AXIS RAPID-S diffractometer (equipped with a two-dimensional area IP detector). Graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å) and oscillation scans technique with ∆w = 5º for one image were used for data collection. The lattice parameters were determined by the least-squares methods on the basis of all reflections with F2 > 2σ(F2). Integration of the intensities, correction for Lorentz and polarization effects and cell refinement was performed using CrystalClear (Rigaku/MSC 3

ACCEPTED MANUSCRIPT Inc.,2005) software [11]. The structures were solved by direct methods using SHELXS-97 [12], which allowed location of most of the heaviest atoms, with the remaining non-hydrogen atoms being located from difference Fourier maps calculated from successive full-matrix least squares refinement cycles on F2 using SHELXL-97 [12]. All non-hydrogen atoms were

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refined using anisotropic displacement parameters. Hydrogen atoms, bonded to carbon and oxygen, were positioned geometrically and allowed a ride on their parent atoms, with Uiso(H)= 1.2Ueq(C, O) or 1.5Ueq(Cmethyl). The most important experimental data, including

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crystal data, data collection and structure refinement details of the structures are summarized

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in Table 1.

Table 1 is here

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2.3. Computational methods

The ground state geometries of synthesized molecules (1a-1k) were obtained using DFT method at B3LYP/6-311+G(d,p) level [13,14] in gas phase. In order to verify that the

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obtained ground state structures are real local minima on the energy surface, the vibrational analysis were done at the same level and used. The Gauge-Independent Atomic Orbital

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(GIAO) approach [15,16] were used in the calculations of 1H and

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C NMR chemical shift

values. All calculations were done using Gaussian 09 program package [17].

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2.4. Synthesis and characterization

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2.4.1. Synthesis of benzil monohydrazone

Benzil monohydrazone was synthesized according to literature method [10]. The structures of the compounds were characterized by spectroscopic techniques such as 1H/13C NMR and

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HRMS analyses. The copies of spectroscopic data can be found in Supplementary data

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(Fig.S1-S32).

2.4.2. General procedure for the Preparation benzylidenehydrazono-1,2-diphenylethan-1-one derivatives

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The compound was synthesized by mixing of benzilmonohydrazone (0.001 mol) and of corresponding aldehydes (0.001 mol) in 15 mL ethanol and two drops of acetic acid. The mixture was refluxed for 1-3 h. and then cooled, filtered and the solid was washed with

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methanol. The compound was recrystallized using ethanol.

(E)-2-(((Z)-4-(dimethylamino)benzylidene)hydrazono)-1,2-diphenylethan-1-one (1a): Yield: 98%, m.p. 178-180 °C. 1H NMR (300 MHz): δ 8.50 (s, 1H); 7.83 (d, J= 5.0 Hz, 2H); 7.787.42 (m, 8H); 7.36 (d, J= 8.9 Hz, 2H); 6.65 (d, J= 9.0 Hz, 2H); 2.95 (s, 6H).

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C NMR (75

MHz): δ 198.0; 164.7; 163.0; 153.0; 135.6; 134.6; 132.9; 131.7; 130.7; 129.7; 129.6; 129.1; 127.3; 120.6; 111.9; 40.0. HRMS (m/z) (M-H)+calculated for C23H21N3O, 356.1763; found 356.1752.

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ACCEPTED MANUSCRIPT (E)-2-(((Z)-4-methoxybenzylidene)hydrazono)-1,2-diphenylethan-1-one (1b): Yield: 86%, m.p. 146 °C. 1H NMR (300 MHz): δ 8.64 (s, 1H); 7.90-7.40 (m, 12H); 6.96 (d, J= 7.0 Hz, 2H); 3.75 (s, 3H).

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C NMR (75 MHz): δ 197.5; 166.3; 162.6; 162.5; 135.4; 134.8; 132.6;

for C22H18N2O2, 343.1447; found 343.1430

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132.1; 130.8; 129.8; 129.7; 129.1; 127.6; 126.2; 114.9; 55.8. HRMS (m/z) (M-H)+calculated

(E)-2-(((Z)-4-hydroxybenzylidene)hydrazono)-1,2-diphenylethan-1-one (1c): Yield: 69%, m.p. 238 °C. 1H NMR (300 MHz): δ 10.19 (s, 1H); 8.58 (s, 1H); 7.83 (d, J= 5.1 Hz, 2H) 7.78-

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7.45 (m, 8H); 7.40 (d, J: 8.6 Hz, 2H); 6.75 (d, J: 8.6 Hz, 2H). 13C NMR (75 MHz): δ 197.6;

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165.8; 162.8; 161.5; 135.4; 134.7; 132.0; 131.1; 129.8; 129.6; 129.1; 127.5; 124.7; 116.2. HRMS (m/z) (M-H)+calculated for C21H16N2O2, 329.1290; found 329.1278. (E)-2-(((Z)-4-methylbenzylidene)hydrazono)-1,2-diphenylethan-1-one (1d): Yield: 74%, m.p. 150 °C. 1H NMR (300 MHz): δ 8.68 (s, 1H); 7.90-7.47 (m, 11H); 7.44 (d, J= 8.1 Hz, 2H); 13

C NMR (75 MHz): δ 197.4; 166.7; 162.8; 142.5;

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7.18 (d, J=7.9 Hz, 2H); 2.38 (s, 3H).

135.3; 134.8; 132.49; 132.3; 131.0; 129.9; 129.8; 129.7; 129.1; 129.0; 127.7; 21.6. HRMS (m/z) (M-H)+calculated for C22H18N2O, 327.1497; found 327.1491.

H NMR (300 MHz): δ 8.75 (s, 1H); 7.90-7.35 (m, 15H). 13C NMR (75 MHz): δ 197.0; 167.1;

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(E)-2-(((Z)-benzylidene)hydrazono)-1,2-diphenylethan-1-one (1e): Yield: 76%, m.p. 143 °C.

162.9; 135.2; 134.9; 133.6; 132.4; 132.2; 129.8; 129.7; 129.3; 129.1; 128.9; 127.7. HRMS (m/z) (M-H)+calculated for C21H16N2O, 313.1341; found 313.1326. 4-((Z)-(((E)-2-oxo-1,2-diphenylethylidene)hydrazono)methyl)benzoic acid (1f): Yield: 56%, m.p. 145 °C. 1H NMR (300 MHz): δ 10.19 (s, 1H); 8.82 (s, 1H); 8.00-7.45 (m, 14H). 13C NMR (75 MHz): δ 197.1; 167.6; 167.1; 162.0; 137.4; 135.1; 135.0; 133.7; 132.6; 132.6; 132.2; 130.1; 129.9; 129.7; 129.2; 129.0; 127.8. HRMS (m/z) (M-H)+calculated for C22H16N2O3, 357.1239; found 357.1240. 6

ACCEPTED MANUSCRIPT (E)-2-(((Z)-4-chlorobenzylidene)hydrazono)-1,2-diphenylethan-1-one (1g): Yield: 63%, m.p. 128 °C. 1H NMR (300 MHz): δ 8.75 (s, 1H); 7.92-7.40 (m, 14H).

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C NMR (75 MHz): δ

197.1; 167.3; 161.8; 136.9; 135.1; 135.0; 132.5; 132.3; 130.5; 129.9; 129.8; 129.5; 129.1;

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127.8. HRMS (m/z) (M-H)+calculated for C21H15ClN2O, 347.0951; found 347.0950. (E)-2-((Z)-(2-hydroxy-3-methoxybenzylidene)hydrazono)-1,2-diphenylethanone (1h): Yield: 91%, m.p. 121-122 °C. 1H NMR (300 MHz): δ 10.12 (s, 1H); 8.98 (s, 1H) 7.83 (d, J=5.0 Hz, 2H); 7.79-7.52 (m, 12H); 7.05 (dd, J1= 1.29, J2= 7.96 Hz, 3H); 6.81 (t, 1H); 3.78 (s, 4H). 13C

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NMR (75 MHz): δ 196.9; 167.9; 158.8; 135.0; 133.7; 132.7; 132.1; 130.6; 129.8; 129.2;

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128.6; 128.0. HRMS (m/z) (M-H)+calculated for C22H19N2O3, 359.1393; found 359.1396. (E)-2-(((Z)-2-chlorobenzylidene)hydrazono)-1,2-diphenylethan-1-one (1i): Yield: 54%, m.p. 120-121 °C. 1H NMR (300 MHz): δ 8.92 (s, 1H); 7.80-7.43 (m, 24H); 7.3 (t, 2H). 13C NMR (75 MHz): δ 158.7; 135.1; 133.6; 130.9; 130.6; 128.6; 128.2. HRMS (m/z) (M-H)+calculated

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for C21H16N2OCl, 347.0951; found 347.0951.

(E)-2-(((Z)-4-fluorobenzylidene)hydrazono)-1,2-diphenylethan-1-one (1j): Yield: 65%, m.p. 164-166 °C. 1H NMR (300 MHz): δ 8.57 (s, 1H); 7.97-7.80 (m, 5H); 7.62-7.29 (m, 10H); 13

C NMR (75 MHz): δ 197.4; 167.5; 166.3; 163.0; 160.7; 135.4; 133.9; 132.6;

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7.21 (t, 3H).

131.5; 130.9; 130.8; 129.9; 129.2; 128.9; 128.9; 127.8; 116.0; 115,7. HRMS (m/z) (M-

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H)+calculated for C21H16N2OF, 331.1249; found 331.1247. (E)-2-(((Z)-(2-hydroxynaphthalen-1-yl)methylene)hydrazono)-1,2-diphenylethan-1-one (1k): Yield: 92%, m.p. 173-174 °C. 1H NMR (300 MHz): δ 11.88 (s, 1H), 9.70 (s, 1H), 8.19 (s, 1H), 8.16 (s, 1H), 8.06 (s, 1H), 8.03 (d, J = 1.5 Hz, 1H), 7.92 (s, 1H), 7.90 (d, J = 1.7 Hz, 1H), 7.70 – 7.36 (m, 6H), 7.07 (s, 1H), 7.04 (s, 1H).

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C NMR (75 MHz): δ 196.9; 166.2; 162.1;

161.2; 135.1; 134.6; 132.6; 131.8; 129.2; 127.9; 123.7, 119.9; 119.0; 108.0. HRMS (m/z) (MH)+calculated for C25H19N2O2, 379.1447; found 379.1447. 7

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3. Results and discussion

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3.1. X-ray crystallographic structure

The crystals of benzilmonohydrazone based Schiff bases were grown in ethanol and/or

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methanol solution through slow evaporation process and suitable crystals were collected and analyzed through single crystal X-rays diffraction analysis. The single-crystal structures with

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atom numbering scheme is illustrated in Fig.1. Selected metrical parameters from X-ray diffraction are listed in Table 1, the average bond lengths and bond angles parameters of ring systems (phenyl, pyridine and naphthalene) are in the normal ranges. The crystallographic data is given in Table 1, which demonstrate that two Schiff bases (1h,1i) crystallized in

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monoclinic system with space groups C2/c and P21/c respectively and the other two (1j, 1k) are crystallized in orthorhombic system with space groups Fdd2 and Pca21 respectively. Dibenzylidene hydrazine units are nearly planar. N-N (hydrazone) distances are in the range

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of typical single bond [1.407(3)-1.430(3) Å]. C=N double bonds in hydrazone units are between 1.264(3)-1.286(3) Å. The torsion angles involving the –N=C– units have values in

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the range of 175.6-178.2º. These torsion angles in all crystals and optimized gas phase geometry are in close agreement with the expected value due to sp2 hybridization of N atom. C-F and C-Cl bond lengths are 1.359(3) and 1.741(3) Å, respectively. All these data have similar values to previous structures [6,18]. The conformations are defined by steric effects, which force a rotation of the phenyl-ketone units relative to the mean plane through the dibenzylidene hydrazine and naphthalene groups. The N2 atom in the molecules 1h and 1k (also N4 in 1k) acts as potent acceptor for O2-H···N2 2.614(3) Å hydrogen bond in which

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ACCEPTED MANUSCRIPT atom O2 donates a proton. This indicates the relatively strong character of the intramolecular hydrogen bonding in these molecules [19]. π-π stacking interactions between the delocalized π-electrons of the phenyl rings are relatively weak. Distance between rings centroids are in the

Figure 1 is here Table 1 is here

3.2. Computational analysis

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3.2.1. Optimized geometries of 1h-1k

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Table 2 is here

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H···Cl interactions (Table 2)

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range of 3.8-5.9 Å. The crystal packings are controlled by non-classical weak C-H···O and C-

The ground state geometries of 1h, 1i, 1j and 1k were obtained at B3LYP/6-311+G(d,p) level in gas phase (Fig. 2). The Ph-carbonyl group is almost perpendicular with the rest of the

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molecule with the torsion angles N1-C7-C8-C9 of -84.22o, -83.63o, 83.72o, 84.85o for 1h, 1i, 1j and 1k, respectively. The groups except of Ph-carbonyl group is planar with the torsion

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angles C6-C7-N1-N2 and N1-N2-C15-C16 (Table 3). The bond lengths N1-N2 are 1.388 Å for 1h, 1.391 Å for 1i, 1.392 Å for 1j and 1.385 Å for 1k. The calculated geometrical parameters are given in Table 3. When the fact the calculated results are obtained in gaseous phase and experimental results are obtained in solid state is taken into account, small differences between the calculated and experimental parameters are expected. Consequently, it is obtained that the calculated and X-ray results are compatible with deviations in the range of 0.002-0.026 Å for bond lengths, 0.005-2.468o for bond angles, 0.013-9.084o for torsions. In

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ACCEPTED MANUSCRIPT addition, when the calculated hydrogen bonding geometry parameters for 1h and 1k are examined, it is seen that they are compatible with the experimental results. The distance O2H…N2 of 2.663 Å and the distance O4-H…N4 of 2.663 Å show the presence of an intramolecular hydrogen bond in 1h and 1k, respectively. However, the distances O2-H (O4-

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H) and H…N2 (H…N4) was as 0.990 Å (0.998 Å) and 1.785 Å (1.710 Å) with the angle O2H…N2 (O4-H…N4) as 146.0o for 1h (1k).

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Table 3 is here

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3.2.2. HOMO-LUMO gaps and global reactivities of 1a-1k

To obtain the information of molecular properties, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were obtained from ground

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state geometries of all studied molecules (1a-1k). The HOMO-LUMO energy gap (∆E) values of 1h-1k are presented in Fig. 2. It is well known that the energy gap gives the useful information about the chemical reactivity and kinetic stability of molecules. The relation

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between the ionization energy (I) and electron affinity (A) and EHOMO and ELUMO values are

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given by Koopmans' theorem [20] as I = -EHOMO and A = -ELUMO. In addition to these, the other important parameters, the electronic chemical potential (µ) and global hardness (η), global electrophilicity index (ω) and softness (s) are related to EHOMO and ELUMO expressed in the following:

µ=1/2(EHOMO+ELUMO)

(1)

η = -1/2(EHOMO – ELUMO)

(2)

ω= µ2/2η

(3)

s = 1/η

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The obtained global reactivity data are given in Table 4. It is well known that the molecular stability and reactivity are characterized by the chemical hardness (η) and softness (s). As seen in Table 4, 1e has the largest the energy gap (∆EH-L =-4.05 eV), i.e. 1e has the largest

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global hardness with η=2.02 eV among studied molecules whereas 1a and 1k have the largest values of softness and the smallest ∆EH-L values, s=0.59 eV-1 ∆EH-L=-3.41 eV and -3.39 eV. As a result, 1e is less reactive than the other studied molecules. On the other hand, the best

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electrophile among the studied molecules is 1f with the highest electrophilicity index (w) of

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5.96 eV and EHOMO=-6.66 eV values, which means its electron donating ability is more than the others.

Figure 2 is here

The

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3.2.3. Chemical Shifts

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Table 4 is here

C and 1H NMR chemical shifts were calculated by DFT/6311+G(d,p) method using 13

C and 1H NMR chemical shifts with respect to

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GIAO approach in DMSO. The obtained

TMS for 1h, 1i, 1j and 1k with the corresponding experimental values with the numbering in Fig.1 are shown in Table 5 and Table 6. Since experimental 1H chemical shift values were not available for individual hydrogen, the average values for CH3 hydrogen atoms are presented. The comparison revealed that there is a good agreement between the calculated and experimental values of chemical shifts for

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C (1H) with R2= 0.97 (0.99) for 1h, R2= 0.93

(0.96) for 1i, R2= 0.99 (0.88) for 1j, R2= 0.96 (0.93) for 1k.

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ACCEPTED MANUSCRIPT Table 5 and 6 are here 3.2.4. Thermal Analysis

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The thermal decomposition of compounds was performed using thermal analytical techniques (TGA) under nitrogen atmosphere. Melting point of compounds was determined by DTA curve. Summary of thermogravimetric analysis was shown in Table 7. The thermal

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decomposition characteristics showed that Shiff bases compounds have excellent stability. All compounds exhibited single sharp step weight loss which starts at above 290 °C. TGA

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thermogram showed that (1d), (1g) and (1i) samples were stable up to 336 °C (Fig.3). The decomposition reaction for other samples generally starts around 300 °C through partial loss of the organic fragment. The order of thermal stability of compounds was (1b) ̴ (1d) ̴ (1g) ̴ (1g) ̴ (1i) ̴ (1k) > (1e) > (1a) ̴ (1f) ̴ (1j) > (1c) ̴ (1h) (Supplementary data (Figs.S33-

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42)). No significant difference and relationship were observed between the stability and substituent type. However, the significantly higher melting point of (1c) and (1f) can be

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explained by intermolecular hydrogen bonding in their crystal structure

Figure 3 is here Table 7 is here

4. Conclusion

In this paper a new series benzilmonohydrazone based Schiff bases derivatives bearing various electron donating and accepting substituents in phenyl ring were synthesized and fully characterized with well-known spectroscopic techniques such as 1H/13C NMR and HRMS as 12

ACCEPTED MANUSCRIPT well as by X-ray diffraction methods for only 4 derivatives. The geometry of the compounds was optimized by the DFT method and the results were compared with the X-ray diffraction data. The obtained results from theoretical calculations are compatible with X-ray data. For determination of thermal stability of synthesized compounds, DTA–TGA analyses were done

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and they have good thermal properties for practical applications especially using as dye. As a result, the benzilmonohydrazone based Schiff bases which were synthesized in this paper, can be used as ligand for complexation of some metal and used as intermediate in the synthesis of

Acknowledgements

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asymmetric and symmetric Schiff bases.

The authors are very grateful to Gazi University Research Fund for providing financial support for this project (grant No. 05/2009-43). The numerical calculations reported in this paper were fully performed at TUBITAK ULAKBIM, High Performance and Grid

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Supplementary material

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Computing Center (TRUBA resources).

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C NMR and HRMS and TGA graphs of

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Supplementary data (Copies of 1H NMR,

compounds, Figs. S1–S12) associated with this article can be found, in the online version, at…..CCDC-1554316 (1h), 1553922 (1i), 1554611 (1j) and 1554316 (1k) numbers contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033; e-mail: [email protected]).

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[10] M. Wieland, W. Seichter, A. Schwarzer, E. Weber, Struct. Chem. Structural Chemistry 22(6) (2011) 1267.

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[11] Rigaku/MSC, Inc., 9009 new Trails Drive, TheWoodlands, TX 77381. [12] G.M. Sheldrick, SHELXS-97, Program for crystal structure solution, University of Göttingen, Germany Göttingen, 1997. [13] A.D. Becke, Density-functional exchange-energy approximation with correct asymptotic behavior, Phys. Rev. A 38(6) (1988) 3098. [14] C. Lee, W. Yang, R.G. Parr, Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density, Phys. Rev. B 37(2) (1988) 785.

14

ACCEPTED MANUSCRIPT [15] R. Ditchfield, J Chem Phys 56(11) (1972) 5688-5691. [16] K. Wolinski, J.F. Hinton, P. Pulay, , J. Am. Chem. Soc. 112(23) (1990) 8251-8260. [17] M. Frisch, G. Trucks, H.B. Schlegel, G. Scuseria, M. Robb, J. Cheeseman, G. Scalmani,

Wallingford, CT 200 (2009). [18] H. Tanak, J. Phys. Chem. A 115(47) (2011) 13865-13876.

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V. Barone, B. Mennucci, G. Petersson, Gaussian 09, revision a. 02, gaussian, Inc.,

Rep Online 63(5) (2007) o2579-o2580.

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[20] T. Koopmans, , Physica 1(1) (1933) 104-113.

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[19] A. Abbasi, G. Mohammadi Ziarani, S. Tarighi, , Acta Crystallogr Sect E Struct

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ACCEPTED MANUSCRIPT

CAPTIONS

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Tables Captions

Table 1. Crystallographic data and structure refinement for the compounds 1h, 1i, 1j, 1k. Table 2. O-H···N intramolecular hydrogen bonds in 1h and 1k and weak intermolecular

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interactions in compounds 1h,1i,1j and 1k

optimization for 1h, 1i, 1j and 1k.

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Table 3. Selected bond distances (Å) and angles (°) from X-ray diffraction and DFT

Table 4. The obtained values of some quantum chemical parameters for 1a-1k. Table 5. Experimental and calculated 1H NMR isotropic chemical shifts (in ppm) for 1h-1k.

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Table 6. Experimental and calculated 13C NMR isotropic chemical shifts (in ppm) for 1h-1k.

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Figure Captions

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Table 7. Thermal properties of compounds.

Fig. 1. A view of the molecular structure of structures 1h, 1i, 1j and 1k with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Fig. 2. HOMO and LUMO orbitals of 1h-1k with the energy gap values (∆E). Fig.3. TGA-DTA thermograms of 1h and 1i samples.

Scheme Captions

16

ACCEPTED MANUSCRIPT

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Scheme. Synthetic pathway of benzilmonohydrazone based Schiff bases.

17

ACCEPTED MANUSCRIPT Table 1. Crystallographic data and structure refinement for the compounds 1h, 1i, 1j, 1k. C22H18N2 O3 (1h)

C21H15N2 O Cl (1i) C21H15N2 O F (1j) C25H18N2 O2 (1k)

Formula weight

358.4

346.80

330.35

378.41

Temperature (K)

293(2)

293(2)

293(2)

293(2)

Wavelength (Å)

0.71073

0.71073

0.71073

0.71073

Crystal system

Monoclinic

Monoclinic

Orthorhombic

Orthorhombic

Space group

C2/c

P21/c

Fdd2

Pca21

Unit cell dimensions (Å,°)

a = 16.5845(5)

a = 15.5363(4)

a = 27.965(4)

a = 22.1505(8)

α = 90

α = 90

α = 90

α = 90

b = 16.3477(5)

b = 9.9624(3)

b = 30.052(4)

b = 5.9877(2)

β = 109.353(2)

β = 96.533(2)

β = 90

β = 90

c = 14.7781(4)

c = 11.5742(3)

c = 8.3099(11)

c = 29.4915(9)

γ = 90

γ = 90

γ = 90

1779.81(2)

6983.7(2)

3911.47(3)

4

16

8

1.294

1.257

1.29

Volume (Å3)

3780.22(3)

Z

8

Density (calculated)

1.26

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(g/cm3)

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γ = 90

Absorption coefficient

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Empirical formula

0.085

0.225

0.086

0.082

1504

720

2752

1584

3.03 -28.4

2.9-26.4

1.38 - 28.4

− 22 ≤ h ≤22,

− 13 ≤ h ≤13,

− 34 ≤ h ≤34,

− 29 ≤ h ≤29,

− 21 ≤k ≤21,

− 16 ≤k ≤16, − 13 ≤ − 37 ≤k ≤37, − 9 ≤ − 8 ≤k ≤8, − 39 ≤

− 19 ≤ l ≤19

l ≤13

l ≤10

l ≤39

Reflections collected

69105

42612

15285

102769

Independent reflections

4772

3444

3610

9604

[R(int) = 0.030]

[R(int) = 0.036]

[R(int) = 0.056]

[R(int) = 0.086]

Data Completeness (%)

99.9

99.3

Refinement method

Full-matrix least-

Full-matrix least-

(mm− 1)

Theta range for data

1.8 - 28.5

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collection (°)

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F(000)

Index ranges

99.1 Full-matrix least- Full-matrix least-

ACCEPTED MANUSCRIPT squares on F2

squares on F2

squares on F2

Data/restraints/parameters

3134/0/248

2605/0/227

2057/0/228

4765/0/523

Goodness-of-fit on F2

1.04

1.019

1.079

1.036

Final R indices

R1 = 0.060

R1 = 0.048

R1 = 0.053

R1 = 0.081

[I > 2sigma(I)]

wR2 = 0.168

wR2 = 0.120

wR2 = 0.090

wR2 = 0.154

R indices (all data)

R1 = 0.089

R1 = 0.098

R1 = 0.075

R1 = 0.181

wR2 = 0.196

wR2 = 0.091

wR2 = 0.118

wR2 = 0.191

0.355 / 0.263

0.160 /0.260

0.137 / 0.141

241 /163

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Largest diff. peak and hole

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squares on F2

ACCEPTED MANUSCRIPT Table 2. O-H···N intramolecular hydrogen bonds in 1h and 1k and weak intermolecular interactions in compounds 1h,1i,1j and 1k. D···A (Å) 2.628(2)


C22-H···O1i

2.68

3.605(4)

163

-x+1/2,+y+1/2,-z+1/2+1

C12-H···O3i

2.67

3.375(4)

133

-x+1/2,-y+1/2,-z+1

C2-H···Cl1i

-x+2,+y-1/2,-z+1/2+2

2.91

3.496(3)

138

i

2.71

3.447(2)

137

C15-H···O1i

2.52

3.336(4)

146

C21-H···O1i

2.67

3.451(4)

142

O2-H···N2

1.84

2.561(4)

146

O4-H···N4

1.89

2.613(4)

C38-H···O2i

2.66

3.461(3)

i

2.71

C12-H···O4i

2.72

C13-H···O1

x,-y+1/2,+z+1/2

x-1/4,-y+3/4,+z+1/4 x-1/4,-y+3/4,+z+1/4

147

144

x,+y-1,+z

3.503(4)

144

x,y,z

3.398(4)

130

x,+y+1,+z

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C11-H···O4

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1k

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1j

(i) Symmetry

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H-A (Å) 0.95

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1i

D-H···A O2-H···N2

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Molecule 1h

ACCEPTED MANUSCRIPT Table 3. Selected bond distances (Å) and angles (°) from X-ray diffraction and DFT optimization for 1h, 1i, 1j and 1k. Parameters

1j

1k

exp.

calc.

exp.

calc.

exp.

C6-C7

1.475(3)

1.477

1.473(2)

1.476

1.473(4)

1.477

1.460(9)

1.477

C7-N1

1.285(2)

1.294

1.286(2)

1.294

1.282(4)

1.294

1.281(8)

1.294

N1-N2

1.405(2)

1.388

1.413(9)

1.391

1.416(3)

1.392

1.430(9)

1.385

N2-C15

1.276(2)

1.299

1.264(2)

1.290

1.268(4)

1.289

1.280(8)

1.304

C15-C16

1.439(3)

1.447

1.456(2)

1.464

C7-C8

1.516(2)

1.529

1.517(2)

1.530

C8-C9

1.477(2)

1.489

1.480(2)

1.491

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1i

C8-O1

1.215(2)

1.223

C21-Cl1

-

-

C17-O2

1.348(2)

1.341

C18-O3

1.362(3)

1.362

O3-C22

1.401(3)

1.421

C19-F1

-

-

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1h

calc.

exp.

calc.

Bond lengths

(o) 121.11(17)

C7-N1-N2

112.33(15)

C7-C8-C9

117.65(14)

O1-C8-C9

123.05(16)

Torsions

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(o)

1.461

1.439(8)

1.442

1.519(5)

1.530

1.511(8)

1.528

1.474(4)

1.491

1.482(8)

1.490

1.223

1.214(4)

1.223

1.212(7)

1.223

1.741(2)

1.763

-

-

-

-

-

-

-

-

1.346(9)

1.338

-

-

-

-

-

-

-

-

-

-

-

-

-

-

1.358(4)

1.357

-

-

120.91

120.77(16)

121.03

120.9(3)

121.045

120.3(6)

120.854

114.79

110.94(14)

113.14

112.1(3)

113.187

113.3(5)

115.023

119.05

118.55(14)

119.18

120.2(3)

119.134

118.5(5)

118.972

122.68

122.65(16)

122.50

122.5(3)

122.505

122.5(6)

122.590

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C5-C6-C7

1.453(4)

1.2162(19)

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Bond angles

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(Å)

C6-C7-N1-N2

-176.68(15)

-179.46

179.56(14)

-179.84

-178.6(3)

179.506

-178.0(5)

179.804

N1-N2-C15-C16

-179.49(17)

-179.99

179.85(15)

179.74

177.6(3)

179.963

180.0(5)

178.745

N1-C7-C8-C9

-93.3(2)

-84.22

-83.1(2)

-83.63

80.5(4)

83.72

-84.2(7)

-84.85

ACCEPTED MANUSCRIPT Table 4. The obtained values of some quantum chemical parameters for 1a-1k. 1d -6.18 -2.26 -3.92

1e -6.31 -2.26 -4.05

1f -6.66 -2.86 -3.80

1g -6.38 -2.47 -3.91

5.96

6.04

6.18

6.31

6.66

6.38

5.85

6.41

6.36

5.86

2.17

2.21

2.26

2.26

2.86

2.47

2.35

2.50

2.40

2.47

-4.06

-4.13

-4.22

-4.28

-4.76

-4.10

-4.45

-4.38

-4.16

1.90

1.92

4.35

4.44

0.53

0.52

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1h -5.85 -2.35 -3.50

1i -6.41 -2.50 -3.91

1j -6.36 -2.40 -3.96

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1c -6.04 -2.21 -3.83

-4.42

1k -5.86 -2.47 -3.39

1.96

2.02

1.90

1.95

1.75

1.96

1.98

1.70

4.54

4.53

5.96

5.02

4.81

5.07

4.84

5.11

0.51

0.49

0.53

0.51

0.57

0.51

0.51

0.59

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Ionization energy (I) (eV) 5.40 Electron affinity (A) (eV) 1.99 Electronic Chemical potential (µ) (eV) -3.69 Global hardness (η) (eV) 1.70 Global electrophilicity index (w) (eV) 4.01 Softness (s) (eV-1) 0.59

1b -5.96 -2.17 -3.79

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HOMO (eV) LUMO (eV) ∆E (eV)

1a -5.40 -1.99 -3.41

ACCEPTED MANUSCRIPT Table 5. Experimental and calculated 1H NMR isotropic chemical shifts (in ppm) for 1h-1k.

EP AC C

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H1 H2 H3 H4 H5 H10 H11 H12 H13 H14 H15 H17 H18 H20 H21

1k cal. exp. cal. 7.7 O2-H 11.9 12.6 7.7 H1 8.2 8.2 7.9 H2 8.1 8.0 8.0 H3 7.8 7.9 9.1 H4 7.7 7.7 8.9 H5 7.6 7.6 8.0 H10 9.7 8.9 8.0 H11 8.2 8.1 7.8 H12 8.2 8.1 8.0 H13 7.7 7.7 9.0 H14 8.2 8.1 8.2 H15 9.7 10.3 7.2 H18 7.4 7.3 7.5 H19 8.2 8.3 7.8 H21 8.2 8.2 H22 7.8 7.8 H23 8.0 8.0 H24 8.2 8.6

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cal. 9.1 8.0 7.9 7.7 7.7 8.9 8.0 8.1 7.7 8.0 9.2 8.2 7.4 7.7 7.7

1j exp. 7.8 7.6 7.9 8.0 8.6 8.6 8.0 8.0 7.8 8.0 8.6 8.0 7.3 7.5 7.8

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H1 H2 H3 H4 H5 H10 H11 H12 H13 H14 H15 H17 H18 C19 H20

1i exp. 8.9 7.9 7.9 7.7 7.7 8.9 7.9 7.9 7.7 7.9 8.9 7.9 7.4 7.7 7.7

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1h exp. cal. O2-H 10.1 10.9 H1 7.9 8.1 H2 7.9 8.0 H3 7.9 7.9 H4 7.7 7.7 H5 7.6 7.6 H10 8.9 8.9 H11 7.9 8.1 H12 7.9 8.1 H13 7.8 7.8 H14 7.9 8.0 H15 8.9 9.1 H19 7.1 7.1 H20 7.2 7.1 H21 7.2 7.2 H22 3.8 3.8 H22 3.8 4.2 H22 3.8 3.8

ACCEPTED MANUSCRIPT Table 6. Experimental and calculated 13C NMR isotropic chemical shifts (in ppm) for 1h-1k.

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25

1k exp. 129.4 132.7 132.7 132.5 132.5 134.8 166.3 197.0 134.8 132.5 132.5 135.1 132.5 134.5 162.2 119.1 161.2 123.8 135.1 132.5 132.5 129.2 132.5 127.9 134.5

cal. 134.2 137.0 140.1 136.1 138.0 141.6 175.1 211.3 142.6 136.2 136.9 144.3 136.6 141.1 172.3 115.7 171.9 124.5 145.5 136.2 137.1 131.0 136.1 126.8 140.9

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cal. 138.1 136.1 140.3 136.8 134.0 141.1 179.0 211.7 143.7 135.2 136.8 143.6 136.6 141.3 172.1 138.7 136.9 123.4 177.4 123.0 143.9

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C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21

1j exp. 130.0 128.9 131.0 128.9 127.8 131.6 167.5 197.4 135.5 127.8 128.9 133.6 128.8 131.6 163.0 130.8 129.2 115.7 166.4 116.0 135.5

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cal. 134.3 136.8 140.8 136.0 138.7 161.5 180.2 212.0 143.0 135.4 136.9 143.8 136.5 141.5 169.4 139.2 136.7 134.4 141.4 138.0 154.1

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C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21

1i exp. 115.9 122.6 130.0 118.5 128.9 163.2 166.9 197.2 135.5 118.5 122.6 148.4 118.8 132.6 164.1 129.3 119.8 115.9 132.2 127.8 148.9

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cal. 134.0 137.0 140.4 136.1 138.1 141.7 176.4 210.9 142.3 135.9 137.0 144.5 136.9 141.3 177.0 124.9 159.5 156.9 121.1 126.0 131.9 57.7

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C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22

1h exp. 129.2 132.7 135.1 132.2 133.7 135.1 168.0 197.0 135.1 129.8 132.7 135.1 130.7 135.1 168.0 128.0 158.8 158.8 128.0 128.5 128.2 40.8

ACCEPTED MANUSCRIPT

DTG max (°C) 324.97 335.91 296.71 336.15 330.07 320.35 336.40 298.17 336.65 321.70 332.11

Mass loss (%) up to 600 °C 95.9 90.7 57.7 89.7 92.2 90.8 88.3 67.1 85.4 -

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1a 1b 1c 1d 1e 1f 1g 1h 1i 1j 1k

Melting point (°C) 186.14 147.51 244.18 170.15 154.54 247.47 141.72 120.01 126.74 167.11 179.70

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Compounds

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Table 7. Thermal properties of compounds.

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ACCEPTED MANUSCRIPT

Fig.1. A view of the molecular structure of structures 1h, 1i, 1j and 1k with atom labelling.

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Displacement ellipsoids are drawn at the 50% probability level.

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ACCEPTED MANUSCRIPT

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Fig.2. HOMO and LUMO orbitals of 1h-1k with the energy gap values (∆E).

Fig.3. TGA-DTA thermograms of 1h and 1i samples.

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ACCEPTED MANUSCRIPT

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Scheme. Synthetic pathway of benzilmonohydrazone based Schiff bases.

ACCEPTED MANUSCRIPT

Highlights •

A new series benzilmonohydrazone based Schiff bases was synthesized and fully

•

The geometry of four compounds were optimized by the DFT method and the results were compared with the X-ray diffraction data.

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The compounds have good thermal properties for practical applications as optic dye.

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•

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characterized.