CHAPTER - VIII STRUCTURE AND VIBRATIONAL...

CHAPTER - VIII

STRUCTURE AND VIBRATIONAL ANALYSIS OF

1-HYDROXY NAPHTHALENE BASED ON

DENSITY FUNCTIONAL THEORY

CALCULATIONS

Abstract

FTIR and FT-Raman spectra of t-hudroxu Naphthalene (HNP) have been

recorded in the regions 4000-400 cm:! and 4000-50 cnri, respectively. The

geometry, frequency and intensity of the vibrational bands of (HNP) was

obtained by the density functional theory (DFT) calculations with Beckeg-Lee-

Yang-Parr (B3LYP) functional and 6-31G** basis set. The assignments have

been proposed with the aid of the results of normal coordinate analysis. The

observed and the calculated spectra are found to be in good agreement. The

results of the calculations were applied to simulate infrared and Raman spectra

of the title compound, which showed excellent agreement with the observed

spectra.

CHAPTER VIII

STRUCTURE AND VIBRATIONAL ANALYSIS OF 1-HYDROXY

NAPHTHALENE BASED ON DENSITY FUNCTIONAL

THEORY CALCULATIONS

8.1 INTRODUCTION

Vibrational spectroscopy is used extensively in organic chemistry, for the

identification of functional groups of organic compounds, for studies on molecular

conformation, reaction kinetics, etc. Due to the great biochemical importance the

vibrational spectral studies of HNP has been carried out in the present

investigation. Naphthalene provides the best raw material for the preparation of

HNP, which is very stable, fused bi-cyclic with a great deal of aromatic character.

Aromatic rings provide the framework for most of dyes. The dyes owes their

colour because of the functional group present in it especially naphthalene plays

vital role in this field besides it is also a valuable insecticide. The Department of

Health and Human Services (DHHS) concluded that naphthalene is reasonably

anticipated to be a human carcinogen [185]. This was also confirmed by the

"Internal Agency of Research of Cancer" (IARC) and Environmental Protection

Agency (EPA). Exposure to large amounts of naphthalene may damage or

destroy some of our red blood cells thus lead to the condition called hemolytic

anemia [154].

Concentration of HNP is measured in urine of 72 adults and 35 young

children from Germany to assess the internal exposure to naphthalene of the

general population. HNP could be detected in more than 90% of the urine

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samples. Levels of HNP (sum of HNP) were 4-fold higher in smokers (median:

37.6 I-1g/gcreatinine) compared to non-smoking adults (8.2 I-1g/gcreatinine). It is

concluded that HNP levels in urine are suitable for human biomonitoring of the

naphthalene exposure in environmental medicines [186-189]. The compound

chosen for the present investigation is used in synthesis of photochemical dyes,

insecticides, pharmaceuticals and other organic compounds.

The goal of the present study is to give a complete description of the

molecular geometry and molecular vibrations of the title compound. The

assignments of bands in the vibrational spectra of molecule are an essential step

in application of vibrational spectroscopy for solving various structural chemical

problems. The calculated infrared and Raman spectra of the title compounds

were also simulated utilizing the scaled force fields and the computed dipole

derivatives for IR intensities and polarizability derivatives for Raman intensities.

8.2 METHODS

8.2.1 Experimental

. The fine polycrystalline samples of HNP is obtained from the Lancaster

Chemical Company, UK and used as such for the spectral measurements. The

room temperature Fourier transform infrared spectra of the title compound is

measured in the 4000-400 crn' region at a resolution of ±1 cm' using KBr pellets

on BRUKER IFS-66V FTIR spectrometer equipped with a cooled MCT detector.

The FT-Raman spectra HNP was recorded on a BRUKER IFS-66V model

interferometer equipped with an FRA-106 and FT-Raman accessory. The

spectra were recorded in the 4000-50 crn' Stokes region using the 1064 nm line

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of a Nd:YAG laser for the excitation operating at 200 mw power. The reported

wave numbers are believed to be accurate within ±1 crn'.

8.2.2 Computational Details

The optimized structure and force field of HNP has been calculated by

using DFT calculation with the hybrid method B3LYP and using the 6-31 G**

basis set. Using the Gaussian 98 program package has carried out all the

calculations [83]. The Cartesian representation of the theoretical force constants

has been computed at the fully optimized geometry by assuming Cs point group

symmetry. The transformation of force field from Cartesian to internal coordinates

the scaling, the subsequent normal coordinate analysis (NCA) and the prediction

of IR and Raman intensities were done by employing the procedure described in

Chapter IV - section 4.3.

The symmetry of the molecule was also helpful in making vibrational

assignments. The symmetries of the vibrational modes were determined by using

the standard procedure of decomposing the traces of the symmetry operation

into the irreducible representations [20]. By combining the results of the

GAUSSVIEW program [156] with symmetry considerations, vibrational

wavenumber assignments were made with a high degree of confidence. There is

always some ambiguity in defining internal coordinates. However, the defined

coordinates form complete set and matches quite well with the motions observed

using the GAUSSVIEW program.

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8.3 RESULTS AND DISCUSSION

8.3.1 Molecular Geometry

The vibrational spectra and the intermolecular hydrogen bonding of HNP

have been studied by considering the. molecule under Cs symmetry. The

computed structure and geometrical parameters of HNP are presented in Fig.

8.1(a). The global minimum energy obtained by the DFT structure optimization

based on B3LYP/6-31G** basis set of HNP is -461.110320095 a.u. The most

optimized geometrical parameters were also calculated and they are depicted in

Table 8.1. In general energy required for the O-H in plane bending is higher since

the hydrogen is more constrained when hydrogen bonded.

8.3.2 Vibrational Force Constants

The output of the quantum chemical calculations contains the force

constant matrix in Cartesian coordinates and in Hartree/Bohr' units. These force

constants were transformed to the force fields in the internal local symmetry

coordinates. The local symmetry coordinates defined in terms of the internal

valance coordinates following the IUPAC recommendations [131,123] are given

in Table 8.2 for HNP. The force fields determined were used to calculate the

vibrational potential energy distribution among the normal coordinates. The

bonding properties of HNP are influenced by the rearrangement of electrons

during the substitution and addition reactions. The possible formation of

intermolecular hydrogen bonding in the title compound may change the values of

the force constants between the bonds. The values of the stretching force

constants between carbon atoms are found to be less than their characteristic

164

values. These results are in good agreement with the changes in the geometrical

parameters.

8.4 MOLECULAR VIBRATIONS AND SIMULATED SPECTRA

The present compound HNP belong to Cs point symmetry and their 51

fundamentals are distributed among the symmetry species as:

IVib = 35A' +16A"

According to the selection rule, both A' and A" vibrations are allowed in

Raman and IR spectra; A' vibrations are totally symmetric and give rise to

polarized Raman lines, whereas A" vibrations are antisymmertic and give rise to

depolarized Raman lines. All the vibrations are active in both Raman scattering

and infrared absorption.

For visual comparison, the observed and calculated (simulated) FTIR and

FT-Raman spectra of HNP are presented in Figs. 8.2 - 8.3 in a common

frequency scale. Comparison between the calculated and observed vibrational

spectra helps us to understand the observed spectral features. The results of the

vibrational analysis viz., calculated unsealed vibrational frequencies, SOM

frequencies, IR intensities, Raman activities, potential energy distributions (PED)

and assignment of the fundamentals, for the title compound HNP are collected

Table 8.3.

8.4.1 Analysis of Vibrational Spectra by SQM Methodology & Assignments

The well known good performance of density functional theory for

estimation of the vibrational spectra of organic compounds can be observed in

the case of the title compound also. The unscaled B3LYP/6-31 G** vibrational

165

frequencies are generally some what larger than the experimental value. This is

true in the case of HNP and it is reflected in the values depicted in Table 8.3.

The RMS error between unsealed and experimental frequencies is 79.2 ern" for

HNP. However for getting reliable information on the vibrational properties, the

use of selective scaling is necessary. The calculated frequencies were scaled

using a set of transferable scale factors recommended by Rauhut and Pulay

[121,172]. The SOM treatment resulted in a RMS deviation of 13.6 crn' HNP.

8.4.2 O-H and C-O Vibrations

The O-H and C-O vibrations are sensitive to hydrogen bonding. The C-O

stretching and O-H bending modes are not independent vibrational modes

because they couple with the vibrations of adjacent groups. Because of the

greater electro negativity of oxygen, the O-H stretching results in a greater

change in bond moment. The C-O stretching mode is coupled with adjacent C-C

stretching vibration, thus in HNP this vibration might better be described as an

asymmetric C-C-O vibration. The hydroxyl stretching vibrations are generally

[160] observed in the region around 3500 crn'. Hydrogen bonding alters the

wavenumbers of the stretching and bending vibrations. The O-H stretching

bands move to lower wavenumbers usually with increased intensity and band

broadening in the hydrogen bonded species near 3250 crn'. In the present

study, the stretching vibrations of hydroxyl groups of HNP are observed at 3310

crn' in FTIR spectrum. The O-H in-plane bending and C-O stretching vibrations

are generally absorbed in the region 1390-1330 cm' and 1260-1180 crn',

respectively, the position of the band depends on the type of the hydroxyl group

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[135]. The most important contribution to C-O stretching mode was at 1180 ern"

for HNP [133]. The FTIR band observed at 1281 ern" is assigned to C-O-H

in-plane bending vibration for the title compound.

The O-H torsional vibration is very anharmonic; for HNP, the wavenumber

of the torsional is observed at 355 crn'.

8.4.3 C-H Vibrations

The aromatic structure shows the presence of C-H stretching vibrations

around 3000 crn'. In HNP these modes were observed at 3085, 3073, 3060,

3052, 3023, 3010 and 3000 crn' in FTIR spectrum and 3060 crn' in Raman

spectrum.

The C-H in-plane bending vibrations are observed in the region 1100-1400

crn' and are usually weak, which interact with CC stretching vibrations. The C-H

out-of-plane bending modes arise in the region 600-900 crn' [7,190]. In the

present study, the bands identified at 1460,1445,1271,1242,1209,1149 and

1045 cm' in HNP were assigned to C-H in-plane bending vibrations in FTIR and

FT-Raman spectra. The C-H out-of-plane bending for HNP is also assigned

within characteristic region and was presented in Table 8.3.

8.5 CONCLUSIONS

Presently, OFT based SQM approach provides the most reliable

theoretical information on the properties of medium size molecules. The overall

good quality of the SQM force field is characterized by the achieved weighted

mean deviation of 13.6 crn' for HNP between experimental and scaled

frequencies. A satisfactory assignment of most of the fundamentals was provided

167

using the scaling procedure. The vibrational wave number, IR intensities and

Raman activities were calculated using B3LYP/6-31 G** method and they were

found to be in good agreement with the experimental values.

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Table8.1

Optimized geometrical parameters of HNP obtained by

B3LYP/6-31 G** density functional calculations

169

Table 8.2Diagonal force constants and internal coordinates of HNP

..................._!!:1!~rna I cog~~i~~!~~~ ....___ . __Q~~~Tip'!~_!?~~In-plane

Diagonal forceconstants?

S1=r213 CH stretch 5.014





S6=r818 CH stretch 5099


S8=r12 CC stretch 6.623


S1O=t34 CC stretch 6.847






S16=r91O CC stretch 5.570



S19=r1112 OH stretch 6.131

S20=r111 CO stretch 5.927

S21=f3123-f3234+f3345-f34510+f35101-f31012 Ring1 def 1.269

S22=-f3234-f3345+2f3123-f35101.f31012+2f34510 Ring1 def 1.221

S23=f3345-f3234+f31012-f35101 Ring1 def 1.485

S24=f39105-f31056+~56r~678+~789-~8910 Ring2 def 1.209

S25=-~1056-~567+2~9105-~789-~8910+2~678 Ring2 def 2.109

S26=~1056-~567+~789-~8910 Ring2 def 1.520

S27=f310111-~2111 CO def 1.361

S28=~1213-~3213 CH def 0.578

S29=~2314-~4314 CH def 0.578

S30=~3415-~5415 CH def 0.581

S31=~5616-~7616 CH def 0.589""""-._-"

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S32=~671r~8717 CH def 0.582

S33=~7818-~9818 CH def 0.584

S34=~8919-~10919 CH def 0.584

S3S=~11112 COH def 0.677

Out-of-plane

S36=Y13231 CH wagg 0.366

S37=Y14342 CH wagg 0.431

S38=Y15453 CH wagg 0.405

S39=Y16675 CH wagg 0.427

S40=Y17786 CH wagg 0.437

S41=Y18897 CH wagg 0.432

S42=Y199108 CH wagg 0.436

S43=Y111210 CO wagg 0.263

S44='t1234-'t2345+'t3456r't45101 +'t5101r't10123 Ring1 tors 0.312

S4S='t1234-'t34510+'t451 01-'t10123 Ring1 tors 0.227

S46=-'t 1234+ 2't2345"'t3451 0-'t45101+ 2'tS101r't 10123 Ring1 tors 0.437

S47=i91 056-'t10567+'t5678-'t5678+'t451 01-'t 78910 Ring2 tors 0.354

S48='t91056-'t5678+'t6789-'t891 05 Ring2 tors 0.371

S49= -'t91056+ 2't 1056r'tS678-'t6789+ 2't 78910-'t891os Ring2 tors 0.290

SSO='t1011112+'t211112 OH tors 0.059

SS1='t45109-'t65101 Butterfly 0.740

"Definitions are made in terms of the standard valence coordinates: ri,j is the bond length between atoms i

and j; ~i,j,k is the valence angle between atoms i,j,k where j is the central atom; )'i,j,k,1is the out-of-plane angle

between the i-j bond and the plane defined by the j,k,1 atoms; 'i,j,k,1is the torsion (dihedral) angle between the

plane defined by i,j,k and j,k,1 atoms.

bStretch, def, wagg and tors mean stretching, deformation, wagging and torsion motions, respectively.

"Stretchinq force constants are given in mdyn A -\ being and torsion force constants are given in mdyn A.

For numbering of atoms refer Fig. 8.1.

171

Table 8.3

Detailed assignment of fundamental vibrations of 1-hydroxy naphthalene by normal mode analysis based on SQM force

field calculations

Observed CalculatedSymmetry frequencies (ern")wavenumbers

SI. species ern" using. 83L YP/6-31 G** IR Raman Characterization of normal modesforce field

No Cs IR Raman unscaled scaled Intensity Activity with PED (%)a

1. A' 3310 - 3753 3310 47.59 148.9 OH s(1 00)

2. A' 3085 - 3227 3077 8.408 127.3 CH s(99)

3. A' 3073 - 3206 3056 18.90 357.4 CH s(99)

4. A' - 3060 3204 3055 41.87 59.66 CH s(99)

5. A' 3052 - 3191 3043 20.00 128.1 CH s(99)

6. A' 3023 - 3186 3038 4.659 59.48 CH s(99)

7. A' 3010 - 3178 3031 1.049 36.56 CH s(99)

8. A' 3000 - 3166 3019 20.53 108.0 CH s(99)

9. A' 1650 - 1688 1649 5.989 6.207 CC s(54) CH b(27) Ring2 b(14)

10. A' 1600 - 1657 1599 61.35 5.139 CC s(54) CH b(32)

11. A' - 1581 1636 1574 19.20 51.55 CC s(59) CH b(24)

12. A' 1578 - 1572 1543 10.56 3.347 CC s(56) CH b(38)

13. A' 1519 - 1514 1509 2.701 22.98 CC s(74) CH b(22)

14. A' 1460 1461 1504 1499 2.016 7.867 CC s(64) CH b(27)

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15. A' 1445 - 1447 1453 9.898 0.708 CC s(70) CH b(18)

16. A' 1376 - 1428 1373 50.04 18.46 CC 8(51) CH b(33)

17. A' 1312 1310 1406 1326 0.460 152.3 CC 8(89)

18. A' 1281 1285 1318 1282 112.7 11.04 COH b(51) CH b(27) CC 5(13)

19. A' 1271 - 1281 1262 8.735 5.231 CC 5(46) CH b(36)

20. A' 1242 1245 1268 1220 2.524 2.333 CC 5(52) CH b(38)

21. A' 1209 - 1232 1199 5.841 0.291 CH b(46) CC 5(43)

22. A' 1180 - 1197 1192 13.16 4.852 CO 8(35) CH b(27) CC 8(25) Ring 1 b( 11)

23. A' 1149 1148 1186 1149 4.679 4.239 CH b(63) CC 5(23)

24. A' 1115 - 1176 1119 81.98 2.913 CH b(43) COH b(41)

25. A' 1045 1045 1110 1055 3.385 9.868 CH b(63) CC 5(14) Ring2 b(13)

26. A' 1015 1015 1069 1013 51.79 8.138 CH b(43) Ring2 b(15) CO 5(13)

COH b(10) CC 8(10)

27. A' - 985 1049 987 24.21 6.329 CH b(72)

28. A 960 - 992 942 0.279 0.073 CH b(88)

29. A" 950 950 963 921 1.581 0.128 CH w(90)

30. A" - 890 954 913 0.002 0.530 CH w(89)

31. A" 877 - 891 870 0.698 2.404 CH w(58) Ring2 t(24)

32. A' 851 - 887 847 6.320 1.732 Ring2 b(51) Ring1 b(21) CC 5(12)

33. A" - 798 853 818 0.467 0.212 CH w(86)

34. A' 790 - 803 790 0.011 6.860 Ring1 b(32) CC 5(32) CO b(24)

35. A' 772 - 800 775 4.361 4.672 Ring1 b(27) CC 8(25) Ring2 b(23)

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36. A" 762 - 788 767 93.72 0.006 CH w(91)

37. A" - 716 745 720 1.103 6.356 CH w(96)

38. A' 711 - 725 712 4.437 21.47 Ring2 b(34) CC 5(33) Ring1 b(10)

39. A" 630 630 645 632 0.436 0.552 CH w(91)

40. A' - 580 585 582 1.946 15.18 Ring2 b(37) CC 5(22) CO b(18)

Ring1 b(10)

41. A" 575 - 584 574 4.710 1.253 Ring2 t(53) CH w(18) Butte t(12)

42. A' 530 - 532 542 4.945 2.707 Ring 1 b(31) Ring2 b(28) CO b( 15)

CC 5(13)

43. A" 484 - 486 482 1.370 5.300 Ring 1 t(42) CH w( 18) Ring 1 t( 17)

44. A" - 480 478 475 3.719 0.740 Ring1 t(29) Ring2 t(25) CO w(14)

45. A" - 467 469 457 0.310 9.480 Ring2 t(46) CH w(34) Ring1 t(14)

46. A" - 428 433 429 0.375 2.212 Ring2 t(59) CH w(14) Ring1 t(11)

47. A" - 355 369 355 114.7 4.859 OH t(90)

48. A' - 290 283 287 5.646 0.729 CO b(29) Ring 1 b(29) CC 5(20)

49. A" - 224 265 226 0.608 0.426 Ring 1 t(36) CO w(25) Ring2 t(24)

50. A" - 171 177 169 5.829 0.022 Butte t(43) CH w(15) Ring2 t(13)

51. A" - 142 143 140 0.018 2.623 CO w(37) Ring2 t(26) Ring1 t(14)

Abbreviations: s, b, wand t mean stretch, in-plane bend, wag and torsion respectively.

apED = potential energy distribution; only contribution larger than 10% are given

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Fig. 8.1 Molecular structure of

1-hydroxy naphthalene along with numbering of atoms

Q)oCell+-':!::

E(j)Celll-

f-

(a)

(b)

4000 5003000 2000 1500 1000

Wavenumber / crn'

Fig. 8.2 FTIR spectra of 1-hydroxy naphthalene

(a) observed (b) calculated

>-+-''(jiC())+-'C

CC1l

EC1l0::

(a)

(b)

4000 5003000 2000 1500 1000

Wavenumber / cm'

Fig. 8.3. FT-Raman spectra of 1-hydroxy naphthalene

(a) observed (b) calculated

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