научная статья по теме AN IR STUDY OF 4(3H)-PYRIMIDINONE IN SOLUTION ADSORBED ON NAX, NAY AND ZSM-5 ZEOLITES Физика

Текст научной статьи на тему «AN IR STUDY OF 4(3H)-PYRIMIDINONE IN SOLUTION ADSORBED ON NAX, NAY AND ZSM-5 ZEOLITES»

СПЕКТРОСКОПИЯ КОНДЕНСИРОВАННОГО СОСТОЯНИЯ

543.42

AN IR STUDY OF 4(3H)-PYRIMIDINONE IN SOLUTION ADSORBED ON NaX, NaY AND ZSM-5 ZEOLITES

© 2015 г. S. Bahgeli* and H. Gokce**

* Department of Physics, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey ** Giresun University, Vocational High School of Health Services, Gure Campus, 28200 Giresun, Turkey

E-mail: semihabahceli@sdu.edu.tr Received February 26, 2004

In this study, the FT-IR spectra of 4(3H)-Pyrimidinone in acetic acid solution adsorbed on NaX (type 13X), NaY and ZSM-5 zeolites are reported. At the same time, the IR wavenumbers of pure 4(3H)-Pyrimidinone molecule (abbreviated as 4(3H)-Pyr), C4H4N2O, were calculated using the DFT/B3LYP level of theory with 6-311++G(d,p) basis set. The obtained IR spectral data indicate that nitrogen ion of the mentioned molecule was adsorbed on zeolites via the hidrogen bondings with the surface hydroxyl groups while some of infrared peaks of 4(3H)-Pyr in solution adsorbed on the title zeolites seem to interfere with the vibrational bands of free zeolites.

ОПТИКА И СПЕКТРОСКОПИЯ, 2015, том 118, № 1, с. 59-63

УДК

DOI: 10.7868/S0030403415010031

INTRODUCTION

Infrared spectroscopy is one of the most powerful tools for the investigations of the adsorbate-adsorbent systems such as zeolites which have the catalytic properties [1—5]. On the other hand, in the last three decades the 4(3H)-Pyrimidinone and similar heterocy-clics were widely studied as one of the nucleobases which play an important role in DNA structures of plant and animal cells [6—9]. Furthermore, the studies of tautomerism of nucleic acid bases have been of con-tinous interest and the keto form of title molecule exists in the gas and condensed phases [10—13]. Meanwhile, ab initio calculations of IR spectra of 4(3H)-Py-rimidinone molecule in Dewar-form and solution were also studied [6,10,14]. Likewise, the hydrogen bonds between nucleobases were also investigated and mainly focused on the intermolecular bondings since hydrogen bonding plays a crucial role in DNA structure [15-17].

One point of our interest about the title molecule is to investigate the formations of intermolecular bonds between adsorbate-adsorbent compounds which can be considered as a heterogenous media while 4(3H)-Py-rimidinone molecule in solution is contained in a homogeneous media. In other words, it can be predicted that the mentioned molecule as a nucleic acid base can be kept in the heterogenous media since its drawing away from this media is more difficult than the homogenous one.

In this framework, the purpose of the present work is to report the IR spectral results of 4(3H)-Pyrimidi-none in the acetic acid solution adsorbed on the zeolites NaX, NaY, and ZSM-5.

EXPERIMENTAL METHOD

The synthetic zeolites NaX (type 13X, Fluka) and NaY (Aldrich) were obtained from commercial sources. The unit cell contents of zeolites NaX and NaY consist of Na86[(AlO2)86 (SiO2)106] • 264H2O and Na56[(AlO2)56 (SiO2)136] • 25OH2O [2, 18]. Furthermore the synthetic ZSM-5 zeolite was obtained from Zeolyst International in NH4 form with mole ratio SiO2/Al2O3 = 30 and surface area 400 m2/g (product number CBV 3024E). The unit cell contents of the zeolite ZSM-5 (Na form) are Na„Al„Si96- nO196 ~ 16H2O where n < 27 and typically about 3 [19]. On the other hand the molecule 4(3H)-Pyrimidinone (Aldrich, 98%) and acetic acid (as solvent) (Merck, 99.9%) were used without any purification. As for the preparations of the samples, first, the zeolites NaX and NaY were activated at 623 K temperature for 4 h while the zeolite ZSM-5 was activated at 673 K for 5 h. Then 1 g of each zeolite was placed into 40 cm3 of 4(3H)-Pyrimidinone solved in acetic acid. The concentration of 4(3H)-Py-rimidinone was 3M. After stirring and storing for 24 h, the mixtures were filtered and washed twice with etha-nol and then filtered again and dried at room temperature.

Samples were compressed into self-supporting pellet and introduced into an IR cell equipped with KBr windows. IR measurments at room temperature were performed on a Perkin-Elmer Spectrum One FT-IR (fourier transformed infrared) spectrometer with a resolution of 4 cm-1 in the transmission mode.

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The infrared wavenumbers (cm and the assignments of pure 4(3H)-Pyr molecule and 4(3H)-Pyr in solution adsorbed on NaX (13X), NaY and ZSM-5 zeolites

Assingments The calculated B3LYP/6-311G(^) for free 4(3H)-Pyr Free 4(3H)-Pyr Exp. Exp. of 4(3H)-Pyr in solution state adsorbed on

unsealed sealed Iir mode No NaX NaY ZSM-5

TCNCN(20) + TCCNC(14) 169.08 166.21 10.162 Mj

TCCNC(44) + TCNCN(44) 357.72 351.64 0.129 M2

SOCC(65) + SCCN(12) 459.42 451.61 9.299 M3 458 m 459 vs 469 s 451 vs

THNCN(53) + yONCC(17) + TCNCN(14) 506.34 497.73 56.271 M4 505 vs 507 w

SCCN(30) + SCNC(28) + vNC(21) 541.47 532.26 0.968 M5 531 vs 556 m 528 sh 563 vs 613 w 535 s 571 s 620 w 543 vs 580 vw 616 w

SNCN(43) + SCNC(16) + 5CCN(13) + vNC(13) 662.00 650.74 0.982 M6 660 m 664 w 646 m

THNCN(76) + TCNCN(10) 717.48 705.29 40.510 M7 668 vw 682 bm 720 m

yONCC(52) + THCNC(15) + TCCNC(13) 760.00 747.08 15.563 Ms 763 s 747 s

SCNC(43) + vNC(24) + 5NCN(11) 828.43 814.34 4.669 M9 818 sh 790 s 795 s

THCNC(51) + yONCC(26) + TCNCN(14) 849.66 835.22 38.609 M10 848 vs 848 bm 834 m 854 s 860 vw

THCNC(77) + TCNCN(11) 949.45 933.31 0.393 M11 917 m 892 sh 898 vw

vNC(39) + SCCN(15) + 5CNC(11) + SNCN(10) 992.18 975.31 37.873 M12 968 sh 948 m

tHCNC(75) + TCCNC(10) 1005.80 988.70 0.072 M13 985 vs 987 vs 1016 vs 1016 vs

SCCN(22) + SCNC(19) + vNC(19) + SHCC(17) 1036.37 1018.75 9.432 M14 1038 vs 1072 sh

vNC(26) + SHNC(26) + SNCN(11) 1134.21 1114.93 11.250 M15 1127vw 1136 m

vNC(29) + SHCC(24) 1208.76 1188.21 8.760 m16 1163 w

SHCN(38) + vNC(28) + 5HCC(12) 1246.54 1225.35 545.493 m17 1230 m 1254 s 1219 w 1250 s 1222 s 1248 vs

SHCN(62) + vNC(13) 1394.86 1371.15 130.382 M18 1375 vs 1371 s 1376 s 1386 m

SHCN(36) + SHCC(25) + 5CCN(11) 1440.95 1416.45 211.867 m19 1428 s 1424 m 1431 m 1419 s

SHCN(39) + vNC(20) + 5HCN(14) 1461.61 1436.76 67.348 m20 1473 m 1477 m 1497 bm 1461 m

vCC(36) + vNC(20) + SHCN(11) 1572.08 1545.35 101.341 m21 1546 s 1553 w 1540 w 1551 s 1501 m 1555 w

vNC(39) + vCC(22) + 5HCN(17) 1644.87 1616.91 781.746 m22 1606 s 1669 m 1603 m 1654 m 1614 vw 1656 m 1608sh 1665 w

vO=C(70) + SCNC(30) 1770.20 1695.85 699.879 M23 1688 vs 1723 s 1670 w 1715 w 1701 s 1719 m 1728 m

vCH(93) 3163.83 3030.95 135.599 M24 3015 m 3035 w 3035 bw

vCH(99) 3169.99 3036.85 87.118 M25 3050 s 3068 vw 3056 w

vCH(94) 3215.24 3080.20 1.058 m26 3100 m 3147 m 3207 w 3260 m 3115 sh 3266 sh 3018 w 3306 sh 3121 bw 3266 w

vNH(100) 3578.39 3428.10 55.302 m27 3411 bm

v, stretching; S, bending; y, out-of-plane bending; t, torsion; s, strong, m, medium; w, weak; sh, shoulder; b, broad; v, very.

(a)

SM-5

NaY

NaX

4(3H)-Pyr

ZSM-5

NaY

NaX

4(3H)-Pyr

4000 3600 3200 2950 1800 1400 1000

600

Wavenumber, cm 1

IR spectra of (a) free 4(3H)-Pyr molecule and (b) 4(3H)-Pyr in solution adsorbed on NaX, NaY and ZSM-5 zeolites.

COMPUTATIONAL METHOD

All calculations were carried out with the Gauss-View molecular visualization program and Gaussian 03 program package [20,21]. In this study, the computations of infrared wavenumbers for the mentioned molecule were done using Becke-3-Lee-Ymg-Parr (B3LYP) density functional method with 6-311++G(J,p) basis set in ground state and the positive values of the vibra-tional wavenumbers show that the optimized molecular structure is stable [22, 23]. Since the computations at this level contain the well-known systematic errors, the calculated vibrational wavenumbers were scaled with 0.958 ranges from 1800 to 4000 cm-1 and were scaled with 0.983 lower than 1800 cm-1 for B3LYP/6-311++G(J, p) level [24, 25]. The assingments of fundamental vibrational modes of title molecule were

performed on the basis of total energy distribution (TED) analysis by using VEDA 4 program [26].

RESULTS AND DISCUSSION

The explicit form of 4(3H)-Pyrimidinone (with synonyms 4(3H)-Pyrimidone, 4-Hidroxypyrimidine, 4-Pyrimidinol, 4(3H)-Pyr briefly), C4H4N2, has 11 atoms and according to normal-mode analysis, the number of the fundamental vibrations is 27. All calculated infrared modes of pure 4(3H)-Pyr molecule are numbered from the smallest to the largest frequencies in Table. The calculated frequency values and the assignments of these modes are in a good agreement with the results obtained previously for the 4(3H)-Pyr molecule [14]. Likewise, the experimental infrared wavenumbers of pure 4(3H)-Pyr molecule and the 4(3H)-Pyr in solution adsorbed on the NaX, NaY and

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ZSM-5 zeolites are also given in Table. On the other hand, Figure shows the IR spectra of pure 4(3H)-Pyr molecule and the 4(3H)-Pyr in an acetic acid solution adsorbed on the synthetic zeolites NaX (type 13X), NaY and ZSM-5 in the intervals 4000-2950 and 1800-400 cm-1, respectively.

By considering Table and Fig. a, the observed peaks at 3411 bm, 3261 m, 3207 w and 3147 m cm-1 for bulk 4(3H)-Pyr molecule can be assigned to the NH stretching vibrational mode [27]. In Fig. a, the peaks at 3437 vs, 3447 vs and 3436 bm cm-1 of the 4(3H)-Pyr in solution adsorbed on the synthetic NaX, NaY and ZSM-5 zeolites, respectively, can be explained by the interferring of the peak at 3411 cm-1 of bulk 4(3H)-Pyr molecule with the structural hydroxyl group frequencies of free zeolites [28]. The other NH stretching bands are observed at 3266 sh, 3306 sh and 3266 w cm-1 (shown with solid arrows in Fig. a) in the IR spectra of 4(3H)-Pyr in solution adsorbed on the NaX, NaY and ZSM-5 zeolites which are slightly shifted to higher wavenumber region and at 3121 cm-1 (shown with an solid arrow) in the IR spectrum of 4(3H)-Pyr in solution adsorbed on ZSM-5 zeolite which is shifted slightly to the lower wavenumber region. Likewise, the observed peaks in the interval 3100-3015 cm-1 in IR spectrum

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