научная статья по теме SPECTROSCOPY STUDIES, CRYSTAL STRUCTURE AND DFT CALCULATIONS OF 4-4{E-[(2-FLUOROPHENYL)IMINO]METHYL}-2-METHOXYPHENOL Физика

ОПТИКА И СПЕКТРОСКОПИЯ, 2015, том 118, № 1, с. 76-86

СПЕКТРОСКОПИЯ КОНДЕНСИРОВАННОГО СОСТОЯНИЯ

УДК 543.42

SPECTROSCOPY STUDIES, CRYSTAL STRUCTURE AND DFT CALCULATIONS OF 4-4{E-[(2-FLUOROPHENYL)IMINO]METHYL}-

2-METHOXYPHENOL

© 2015 г. Can Ala§alvar*, Mustafa Serkan Soylu**, Zeliha Hayvali***, Hüseyin Ünver***

* Department of Electric and Energy, Giresun University, 28100 Giresun, Turkey ** Department of Physics, Giresun University, 28100 Giresun, Turkey *** Ankara University, Faculty of Science, Department of Chemistry, TR-06100 Tandogan, Ankara, Turkey

E-mail: nustafa.serkan.soylek@giresun.edu.tr Received March 3, 2014

The title compound 4{E-[(2-fluorophenyl)imino]methyl}-2-methoxyphenol has been synthesized and characterized by using FTIR, 1H and 13C NMR spectroscopic, and X-ray crystallographic techniques experimentally and using B3LYP/6-31G (d, p) method theoretically. The structure of the compound is stabilized by four intermolecular non-classical hydrogen bonds and an intramolecular interaction. As a result of all intermolecular interaction, non-classical hydrogen bonds that give rise to 2D network structures on the (100) plane. The crystal packing shows a tubular channel running parallel to the c axis. The solvent accessible void occupies a volume of 77.9 A3. The molecular geometry, vibration frequencies, and gauge including atomic orbital (GIAO) 1H and 13C chemical shift values of the title compound in the ground state have been calculated using the density functional (B3LYP) with the 6—31G (d, p) basis set. The calculated results show that the optimized geometry parameters, the theoretical vibration frequencies, and chemical shift values show good agreement with experimental values. In addition, HOMO — LUMO energy gap, molecular electrostatic potential map, thermodynamic properties for the compound were performed at B3LYP/6-31G (d, p) level of theory.

DOI: 10.7868/S0030403415010080

INTRODUCTION

Schiff bases are well known because extensively use as ligands in the field of coordination chemistry [1—4]. A large number of Schiff base compounds have gained importance because of physiological and pharmacological activities associated with them. Vanillin is most prominent as the principal flavor and aroma compound in vanilla. Synthetic vanillin is used as a flavoring agent in foods, beverages, and pharmaceuticals [5—9]. Essential oil of vanillin was and is sometimes used in aromatherapy. This flavoring compound, due to its an-tioxidant ability, may have potential to prevent oxida-tive damage to membranes in mammalian tissues and thereby the ensuing diseased states [10—12]. Also some of the Schiff bases derived from vanillin were evaluated for their potential as antibacterial agents some Gram positive and Gram negative bacterial strains [13]. Only few transition metal complexes of vanillin were reported [14, 15].

We have focused our attention on the synthesis and characterization of various Schiff bases compounds derivatives and studied their special properties [16—19]. To best of our knowledge, neither the synthesis nor theoretical studies of the title compound of synthesis of 4{E- [(2-fluorophenyl)imino]methyl}-2-methox-yphenol have been available until now. The scientists

use computational methods which are reliable to characterize the molecule because of their efficiency and accuracy with respect to the evaluation of a number of molecular properties [20]. A suitable quantum chemical study is helpful to predict compound properties economically and to clarify some experiment phenomena insightfully. In this respect, the computational researches on compound properties tend to increase [21, 22].

In this paper, the title compound was synthesized and characterized by using FT-IR, 1H- and 13C-NMR, X-ray technique and DFT methods. Hydrogen bond geometry of the molecule was determined by X-ray technique. In addition, the properties of structural geometry, molecular electrostatic potential map, ther-modynamic properties and frontier orbitals for the compound were studied at DFT/B3LYP/6-31G (d, p) level.

EXPERIMENTAL DETAILS

Synthesis

Vanillin (0.013 mol) and 2-fluoro aniline (0.013 mol) were dissolved in methanol (30 mL). The mixture was stirred at room temperature for 30 min to give a clear yellow solution. Suitable crystals (Fig. 1) of

O.

CH3

Fig. 1. Numbering of the protons and carbons.

the title compound for X-ray study were formed by slow evaporation of the solvent over 2 days at room temperature. Yield 2.91 g (90%). m.p. 130°C. Anal. Calc. for C14H12O2NF: C, 68.56; H, 4.93; N, 5.71. Found: C, 68.63; H, 4.55; N, 5.37. IR (cm-1); vC=N; 1588, vC=C; 1514, vC-H; 2964; 2941, vC-O; 1283; 1160. 1H-NMR (Numbering protons and carbons were given in Fig. 1.) (DMSO, 8 ppm): 3.85 (OCH3, s, 3H);

m,

6.93 (H12, d, 1H, J = 8.09 Hz); 7.28-7.18 (H

3,4,5,13

4H), 7.37 (H6, dd, 1H, J = 6.63 Hz, j = 1.51 Hz), 7.55 (H9, s, 1H), 8.46 (HC=N, s, 1H), 9.86 (OH, bs, 1H). 13C-NMR (DMSO, TMS, 8 ppm): 56.03 (OCH3);

Table 1. Crystal data and structure refinement for the title compound

Formula C14H12NO2F

Formula weight 245.25

Temperature, K 100.15

Crystal system Tetragonal

Space group P43212

a, Â 12.7581(2)

b, Â 12.7581(2)

c, Â 14.6508(4)

Volume, Â3 2384.70(8)

Z 8

Pcalc, mg/mm3 1.366

p., mm-1 0.102

F(000) 1024.0

Crystal size, mm3 0.44 x 0.4 x 0.36

29 range for data collection 4.52° to 56°

Index ranges -16 < h < 16, -16 < k < 16, -19 < l < 18

Reflections collected 13246

Independent reflections 2696 [R(int) = 0.0280]

Data/restraints/parameters 2696/0/165

Goodness-of-fit on F2 1.071

Final R indexes [I > 2ct(I)] Rx = 0.0307, wR2 = 0.0744

Final R indexes [all data] R1 = 0.0398, wR2 = 0.0822

Largest diff. peak/hole, e Â-3 0.14/-0.21

Flack parameter [36] 0.5(7)

111.07 (C9); 115.88 (C12); 116.42 (C3, J = 19.9 Hz); 122.05 (C13); 124.93 (C6); 125.33 (C5, j = 3.5 Hz); 126.79 (C4, J = 7.5 Hz); 128.12 (C8); 140.50 (C1, J = = 10.3 Hz); 148.52 (C11); 151.15 (C10); 154.08, 156.52 (C2, J = 246.10 Hz); 163.05 (C7 = N).

Materials and Measurements

All reagents and solvents for synthesis and spectro-scopic studies were commercially available and used as received without further purification. Melting points were measured on a Gallenkamp apparatus using a capillary tube. 1H-, 13C-NMR spectra were obtained on a Bruker DPX FT-NMR (400 MHz) ultrashield spectrometer. FTIR spectra were recorded on a Matt-son 1000 FTIR spectrometer in KBr discs and were reported in cm-1 units.

Crystal Data for the Title Compound

The data collection for the compound was performed on a STOE IPDS-2 diffractometer employing graphite-monochromatized Mo^a radiation (X = = 0.71073 A). Data collection, reduction and corrections for absorption and crystal decomposition for title compound were achieved using X-AREA, X-RED software [23]. The structure was solved by SHELXS-97 and refined with SHELXL-97 [24, 25]. The positions of the H atoms bonded to C atoms were calculated (C-H distance 0.96 A), and refined using a riding model. The H atom displacement parameters were restricted to be 1.2 Ueq of the parent atom. The details of the X-ray data collection, structure solution and structure refinements are given in Table 1. The molecular structures with the atom-numbering scheme and optimized geometry are shown in Fig. 2 [26]. Crystallo-graphic data (excluding structure factors) for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 691504 [27].

COMPUTATIONAL DETAILS

GAUSSIAN03 [28] program package was used for DFT calculations. Starting geometries of compound were taken from X-ray refinement data. The molecular structure of the compound in the ground state is optimized by density functional theory (DFT) with 6-31G(d, p) basis set. In DFT calculation, hybrid functional is also used, the Becke's three parameter functional (B3) [29] which defines the exchange functional as the linear combination of Hartre-Fock, local and gradient-corrected exchange terms. The B3 hybrid functional was used in combination with the correlation functional of Lee, Yang and Parr [30]. For the compound, vibration frequencies were calculated by using DFT/B3LYP with 6-31G(d, p) basic set. The calculated frequencies were scaled by 0.9627 [31]. Af-

Fig. 2. (a) ORTEP plots of 1 with atom numbering schemes. Displacement ellipsoids are represented at 50% probability levels. H atoms are shown as small spheres of arbitrary radius. (b) The theoretical structure of the title compound (B3LYP/6-31G(d, p) level).

ter that, the vibration bands were assigned by using chemical shifts were calculated. The standard

Gauss-View molecular visualization program [32]. GIAO/B3LYP/6-31G(d) (gauge-independent atomic

Both geometries ofthe title compound and tetrameth- orbital) approach [33, 34] applying B3LYP with

ylsilane (TMS) were fully optimized. 1H and 13C 6-31G(d, p) basic set was used for these calculations.

Table 2. Comparison of bond lengths and torsion angles of Schiff base

Ref. code C1-C2, A C1=N1, A N1-C9, A C9-N1-C1-C2, deg

The title compound 1.454 (2) 1.283 (2) 1.418 (2) 177.5 (1)

Iteloi [37] 1.461 (3) 1.275 (3) 1.429 (3) 178.6 (2)

Lalxol [38] 1.450 (3) 1.272 (3) 1.430 (2) 179.9 (2)

Suvmol [38] 1.452 (2) 1.271 (2) 1.436 (2) 176.4 (1)

Vukdek [40] 1.454 (2) 1.284 (2) 1.424 (2) 170.5 (3)

Ineyac [41] 1.445 (2) 1.284 (2) 1.421 (2) 177.5 (2)

Mozpat [42] 1.427 (3) 1.292 (3) 1.407 (3) 179.0 (2)

Motlir [43] 1.463 (2) 1.281 (2) 1.428 (2) 175.5 (1)

Rishad [44] 1.457 (2) 1.283 (2) 1.424 (2) 171.1 (2)

Winnaj [45] 1.429 (2) 1.288 (2) 1.410 (2) 179.7 (2)

Yifyao [46] 1.456 (3) 1.272 (3) 1.415 (3) 176.0 (2)

Dawfaj [47] 1.439 (3) 1.290 (2) 1.408 (3) 173.1 (2)

Wefteh [48] 1.458 (3) 1.273 (3) 1.427 (3) 175.8 (2)

Gapfek [49] 1.471 (5) 1.274 (5) 1.417 (5) 178.2 (4)

Lanzor [50] 1.455 (3) 1.268 (2) 1.424 (2) 176.0 (2)

Table 3. Hydrogen bond geometry

D-H...A D-H, Â H. . .A, Â D . . .A, Â D-H...A,

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