Experimental Theoretical HF DFT 3'-Azido-2'-Deoxythymidine

8/4/2019 Experimental Theoretical HF DFT 3'-Azido-2'-Deoxythymidine

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Asian Journal Of Spectroscopy (2008) , 12, 163167

ComparisonofexperimentalandabinitioHFandDFTvibrational

spectraof3'Azido 2' deoxythymidine

Y.P.SINGH*, RATNESH DASb and ARVIND SINGH TOMARc

*Department of Physics, Govt. Polytechnic College, Sagar (MP),INDIA,470001E-mail: [email protected]

bDepartment of Chemistry, Dr. H.S.Gour University, Sagar (MP), INDIA, 470001,E-mail:[email protected]

cDepartment of Physics, S.V.Polytechnic College, Bhopal (MP)

Abstract

A combined experimental andtheoretical study on molecular andvibrational structure of 3-Azido-2-deoxythymidine (Zidovudine AZT) hasbeen reported. The Fourier transforminfrared spectra of was recorded in the

solid phase, in the region of 2500400cm-1. Assuming Cs point symmetry,vibrational assignments for theobserved frequencies have beenproposed by means of quantumchemical calculations using densityfunctional theory and HartreeFockmethod with 6-311++G** basis sets. Anassignment of normal modes ofvibration to the observed andexperimental frequencies has beenbased on these calculations. Thetheoretical wavenumbers showed verygood agreement with the experimentalvalues. A detailed interpretation of theinfrared also is reported.The theoreticalFT-IR spectra of the title molecule havealso been constructed.

Keywords3'-Azido-2'-deoxythymidine,Zidovudine,FTIR Spectra, Hartree-Fock, DFT, AM1,

PM3.1.Introduction

AIDS is , not a disease but acollection of seventy or more conditions

which result from the damage done to

the immune system and other parts of

the body as a result of infection by

HIV1. There are a number of drugs that

have been considered as to be anti HIV.

The drugs like 3'-Azido-2'-

deoxythymidine (AZT), synthesized by Jerome Horowitz, and ribavirin appear

most promising because both cross the

blood-brain barrier and can be taken

orally, and in early traities they do not

cause serious side effects2-4.


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Conformational analysis of AZT

structure and other related drugs have

been previously reported at semi

empirical and ab initiolevels of theory 5-

6. Hernndez7 at al reported an ab initio

HF and DFT study of the dipole

polarizability of AZT drug.

In the present work we have

recorded infrared spectra of AZT drug.

A quantum chemical investigation

using DFT and HF techniques with

moderately extensive basis sets havealso been performed to help in the

assignments of the observed

frequencies. The geometry of the drug

molecule is also reported.

2.Experimental

All the chemicals used to prepare

experimental sets were of Analar /BDH

grade. Zidovudine was purchased from

Cipla India Ltd. I.R. Spectrum has been

recorded using KBr disc in solid phase

in the range 400-2500cm-1 on Perkin-

Elmer spectrometer Model 397.

Preparation of KBr Pallets: A

small amount of finally grounded solid

sample was intimately mixed withabout 100 times or more than its

weight of Potassium bromide powder.

The finely ground mixture was than

pressed under very high pressure in a

press (about 10/cm2) to form a small

pallet (about 1-2 mm thick and 1cm in

diameter).

The accuracy of the

measurements was estimated to be within 3cm-1 and the resolution was

better than 2cm-1 through the entire

spectra.

3.ComputationalMethods

The AM1 and PM3 semi

empirical approaches were performed

as implemented in MOPAC program8

and the PRECISE keywords were used.

Hartree-Fock and DFT calculations

were performed using Spartan' 06

program 9 at the B3LYP 10 levels of

theory with 6-311++G** basis sets.

4. ResultsandDiscussions

MolecularGeometry

The geometry parameters

optimized at AM1, MP2 and B3LYP

levels of theory for Zidovudine are

presented in Table 1. Results indicate

that bond distances and bond angles

are very close to those reported from X

ray structure4. Our results shows that

the Azide group lies in a nonlinear

conformation, where N14N32N16 bond

angle range from 70.058 at PM3 to the

value of 69.367 at B3LYP level and is

attached in transposition to the C6C12

bond of Furancose ring.


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A statistical analysis shows a

mean values of 1.410 , 1.429 and

1.388 and standard deviations of

0.1472 0.03468 , 0.1487 0.03504

and 0.1314 0.03097 calculated

and experimental bond distances using

AM1, PM3 and B3LYP methods. There

is some difference due to due to

electron withdrawing property of

oxygen5 and that of nitrogen between

experimental and calculated bond

lengths in C-O of thymine and

Furancose ring and N-N of Azide ring.

Similarly, bond angles have a mean

value of 116.7 , 117.0 and 116.9 and

standard deviation of 13.603.401 ,

13.163.291 , 13.913.478 at AM1,

PM3 and B3LYP approach.4.2.Vibrationalassignments

3'-Azido-2'-deoxythymidine (AZT)

has a planar structure of Cs point

group symmetry and has 32 atoms so

that it has 90 normal modes of

fundamental vibrations which span the

irreducible representations: 60 a and

30 a. The observed FTIR frequencies

for various modes of vibrations are

presented in Table 2. Vibrational

frequencies calculated at 6311++G**

basis level were scaled by 0.96, and

those calculated at HF level were scaled

by 0.8912 .

The calculated frequencies are

slightly higher than the observed values

and this is due to the fact that the

experimental values are an anharmonic

frequencies while the calculated values

are harmonic frequencies.

4.3.CHvibrations

No peaks were observed

experimentally for the CH stretchingmodes, whereas, the calculated values

are at 3143.81 , 3142.39, 3094.79,

3072.90, 3039.39, 3020.78, 3015.48

cm-1 by DFT method and 3087.32,

3077.40, 3069.05, 2993.79, 2907.71,

2805.41, 2639.90 cm-1 by HF method.

Experimentally out-of-plane

bending vibrations are recorded at

about 1387, 1191,914 and 817 and

974 cm-1 . The corresponding scaled

frequencies are calculated at 1397.07,

1213.16, 944.84, 821.85 cm-1 (DFT )

and 1390.55, 1206.15, 981.27, 828.62

cm-1 ( HF). The changes in the

frequencies of these deformations

determined by the relative position of

the substituents and are almost

independent of their nature13.

4.4.NHvibrations


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The calculated value NH is at3462.52 cm-1 ( DFT) and 3359 cm-1 (

HF ) shows excellent agreement with

experimentally FT-IR value 3485 cm-1

obtained by Rai14. The in-plane and

out-of-plane bending are assigned at

1448.67, 889 cm1 ( DFT ) and 1437.60,

676 cm -1 ( HF ) also agrees well with

Rai14.

4.5.OHvibrations

The OH group gives rise to three

vibrations-stretching, in-plane bending

and out-of-plane deformations. Tayyari

et al 15 observed that the frequency of

OH stretching vibration in the gas

phase is 2800 cm-1 in the case of

banzoylactone. In our case the

calculated frequencies are 3472.69 cm-1

( by DFT) and 3489.65 cm-1 ( by HF).

This deviation is due to presence of

strong intramolecular hydrogen

bonding. Krishnakumar et al16

observed the in-plane bending

vibration in substituted pyridine lies in

the region 11761243 cm1.

Experimental frequencies have not been

observed. The computed value is

1554.01 cm-1 ( DFT) and 1567.50

1554.01 cm-1 ( HF) and it coincides

with CH in-plane bending and CO

stretching. Experimental value of out-

of-plane deformation was 355 cm-1 and

it coincides with out-of-plane

deformation of NN of Azide group. The

calculated values of this vibration at

364.19 cm-1 show excellent agreement

with experimental results17.

4.6.COvibrations

CO stretching vibration has not

been shown experimentally .But


(by DFT) and 1332.56 cm-1 (by HF).

This is in agreement with experimental

frequencies 1244 cm1 (FTIR) and 1249

cm1 (FT-Raman) as obtained by

Sundaraganesan et al18. The in-plane

bending vibration mode with the

theoretical frequency of 452 cm1

deviates positively by 200 cm1 from

experimental value obtained by

Sundaraganesan et al28. This may be

due to mixing of CO vibration with CC

in-plane bending vibration.

4.7.NNvibrationsWe hadn't observed the

asymmetric stretching vibration .But


( DFT) and 2621.94 cm-1 (HF). This is

higher than the experimental

frequencies 2208 cm1 (FTIR) reported

by Jensen19, because the bond from the


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central nitrogen atom to the attached

Furancose ring has partial double bond

character. As a consequence of the

increased delocalization, the N=N

vibration is shifted to lower wave

numbers.

Also calculated Symmetric

stretching frequencies are 1508.75 cm-1

( DFT) and 1489.23 cm1 (HF). Jensen19

reported it at 1253 cm, difference is

due to the large polarizability derivative

associated with the NN stretch.

The in-plane vibration mode with

the theoretical frequency of 430.13 cm1

( DFT) and 426.19 cm1 ( HF) deviates

very little from experimental value 451

cm1 reported by Jensen.

We observed out-of--plane-

bending at 441 cm1 and calculated

frequencies at 442.68 cm1 ( DFT) and

439.89 cm1 ( HF). Also, NN scissoring

frequency was observed at 406 cm1

and calculated frequencies were at

417.29 cm1 ( DFT) and 410.12 cm1 (

HF). This frequency is not reported by

Jensenand Zimmermann et al20.

Figure 4 and 5 shows agreement

between the experimental and

calculated wavenumbers (HF and DFT).

The graph is linear which shows that

theoretical and experimental results are

in good agreement.

5.Conclusion

Attempts have been made in thepresent work for the proper frequencyassignments for the 3'-Azido-2'-deoxythymidine from the FT-IR spectra.Any discrepancy noted between theobserved and the calculated frequenciesmay be due to the fact that thecalculations have been actually done ona single molecules in the gaseous state

contrary to the experimental valuesrecorded in the presence ofintermolecular interactions. Also,difference is attributed due to neglect ofanharmonicity and incompleteinclusion of electronic correlationeffects. Therefore, the assignmentsmade at higher levels of theory withonly reasonable deviations from theexperimental values, seem to be

correct. The B3LYP method is seen tobe better than both RHF and MP2methods for calculation of vibrationalfrequencies. For further agreementbetween computed and experimentalfrequencies, the computed frequenciesare often scaled by some specific factor.

6.Refrences

1. Dossier P, AIDS and ThirdWorld, The Panon Institute ofLondon(1988).


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2. Yarchoan R, Mitsuya H, BroderS. AIDS therapies. Sci. Am,259(4), (1988),110

3. Alan Howie,[email protected],www.abdn.ac.uk/chemistry/rese

arch/rah/rah.hti, 2006.4. Dyer, I.D; Low,J.N; Tollin, P.T.;

Wilson, H.R; and Alan Howie;Acta Crystal, ,C44, (1988),767.

5. Baumgartner, M. T. ; Motura, M.I. ; Contreras, R. H.; Pierini, A.B. ; M. C. Brin, Nucleos.Nucleot. & Nucleic Acids, 22,(2003) 45.

6. Xinjuan, H; Mingbao,H; Dayu,Y;Sci. China Serie B: Chemistry, 45,(2002),470.

7. Hernndez,J; Soscn,H; andHinchliffe,A; Internet ElectronicJournal of Molecular Design,2,(9), (2003), 589.

8. Win MOPAC- Molecular OrbitalProgram, Fujitsu Limited, (1997).

9. Spartan' 06 for MedicinalChemistry, wave function Inc,(2006).

10.A.D.Becke, J. Chem. Phys.,98,(1993), 5648.

11.

Nakamura, M.; Makino, K; Sirgi,L; Aoki, T and Hatanaka, Y.Surface and Coatings, ,769,(2003), 699.

12.Altun A, Golcuk K, Kumru M, J.Mol. Struct. (Theochem.), 637,(2003),155

13.Varsanyi, G; Acta Chim. Hung,,50, (1966), 225.

14.Rai A.K, Kumar S, Rai A; Vib.Spect; ,42, (2006), 397.

15.Tayyari S F, Emampoure J S,Vakili M, Neokoei A R,

Hassanpour M; J. Mol. Struct;,794, (2006), 204.

16.Krishnakumar V andMuthundesan S; SpectrochimActa A; , 65, (2006), 818.

17.Sundaraganeshan N, Anand B, Jian F F, Zhao P,Spectrochimacta A; 65, (2006)826.

18.Sundaraganesan, N; Anand, B;and Dominic Joshua,B;

Spectrochimica ActaA,doi:10.1016/j.saa.2006.07.016,(2006).

19.Jensen, J.O; J.Mol. Structure,730, (2005), 235.

20.Zimmermann,F; Lippert,T;Beyer,C; Stebani,J; Nuyken,Oand Wokaun,A; AppliedSpectroscopy, 47(7), (1993), 986.


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C3

C5

C7

C1

O1 9

N4 H

2 0

N2

C8

H2 2

H2 3

H2 1

C1 2

C6

O9

H2 6

H2 5

N1 4

N1 6

C1 3

H2 4

H2 7

H28

N3 2

H1 8

O1 7

H3 0 H

2 9

O15

H3 1

Fig1Structureof3'Azido2'deoxythymidineorZidovudine

Fig 2: Experimental I. R. Spectra of 3'-Azido-2'-deoxythymidine/ Zidovudine (AZT)

Fig 3: Theoretical I. R. Spectra of 3'-Azido-2'-deoxythymidine/ Zidovudine (AZT)Table1.Optimizedbonddistances(inAngstrom),bondanglesandtorsionangles

(indegrees)ofAZT.


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Bondlength (A0 )

BondAngle (Degree)

Bond Experim

ental14

AM1 PM3 B3LYP BondAngle Experimental14

AM1 PM3 B3LYP

C1N2

N2C3

C3N4

C5N4

C5C7

C7C1

C1O17

C7C8

C8H21

N2H18

C3O19

C5H20

N4C10

C10O9

C10C6

C6C12

C12C11C11O9

C11C13

C13O15

C12N14

N14N16

N16N32

N32N14

1.384

1.368

1.372

1.386

1.332

1.197

1.503

1.201

1.463

1.391

1.535

1.529

1.414

1.515

1.405

1.467

1.231

1.100

1.391

1.391

1.391

1.391

1.391

1.391

1.107

1.542

1.694

1.095

1.095

1.095

1.456

1.401

1.598

1.581

1.9461.511

1.591

1.483

1.492

1.316

1.245

1.729

1.391

1.391

1.391

1.391

1.391

1.391

1.113

1.557

1.703

1.109

1.116

1.115

1.498

1.451

1.603

1.608

1.9931.549

1.612

1.506

1.507

1.359

1.281

1.937

1.389

1.379

1.382

1.390

1.347

1.381

1.168

1.502

1.597

1.101

1.205

1.116

1.456

1.404

1.551

1.568

1.9991.421

1.523

1.476

1.473

1.246

1.108

1.827

C1N2C3

C1N2H18

N2C1O17

N2C3O19

C3N4C5

C7C8H21

H21C8H22

C7C5H20

C5N4C10

N4C10H27

N4C10O9

H27C10C6

C11O9C10

C10C6C12

C10C6H26

O9C11C12

C11C12C6C11C13O15

C13O15H31

H30C13O15

C6C12N14

C5C7C1

C5C7C8

C13C11O9

N4C10C6

N14N16N32

N16N32N14

N32N14N16

N2C3N4

130.4

123.1

119.1

117.9

107.8

110.2

98.8

104.7

105.6113.5

111.1

120.0

120.0

120.4

162.3

113.0

120.000

120.000

120.000

120.000

120.000

57.245

49.517

120.000

118.953

120.269

108.329

77.519

111.538

99.157

106.681

103.184

105.995114.382

141.357

29.462

113.346

121.634

119.924

120.996

160.534

47.165

59.378

73.057

110.0

120.000

120.000

120.010

120.00

120.060

58.058

40.349

121.658

119.359

121.647

109.264

76.927

112.327

100.062

106.992

104.194

104.367115.216

140.581

20.421

114.624

120.347

120.068

120.624

159.458

48.619

50.058

81.363

111.621

121.364

121.620

120.072

120.095

120.012

57.289

40.362

120.00

118.168

120.035

107.984

77.568

110.489

99.008

106.687

104.842

105.996113.859

141.887

29.564

112.549

120.006

120.068

120.001

162.547

47.245

59.367

73.380

112.895

Table 2: Experimental, Calculated Frequencies and Potential Distribution in

Zidovudine (AZT)

S.N. ExperimentalCalculatedFrequencies(incm

1)

VibrationalAssignments


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Frequencies

(incm1)

HF DFT(B3LYP) AtomPair/Energy

Contribution(in%)a

Species a

1 3472.69 3489.65 O15 H31(99.5) s(HydroxylGroup)

2 3462.52 3359.25 N2H18(99.3) a(ThymineRing)

3 3331.98 3294.36 015H31(99.5) a(HydroxylGroup)4 3190.12 3166.24 C10H27(97.7) a(AzideRing)

5 3143.81 3087.32 C8H22(32.9)

C8H21(29.2)

C8H23(24.7)

s(ThymineRing)

6 3142.39 3077.40 C5H20(86.0) s(ThymineRing)

7 3094.79 3073.82 C11H24(54.9) s8 3084.79 3069.05 C6H26(70.1)

C6H28(28.4)

s(FurancoseRing)

9 3072.90 2993.62 C13H29(92.1) s(HydroxylGroup)

10 3055.24 2988.79 C8H22(55.8)

C8H21(39.2)

s (ThymineRing)

11 3039.39 2907.71 C8H23(66.4)

C8H21(26.5)

a (ThymineRing)

12 3020.78 2805.41 C11H24(38.8)

a (FurancoseRing)

13 3015.48 2639.90 C6H28(68.4)

C6H26(29.8)

a(FurancoseRing)

14 2612.89 2621.64 N16N32(71.7)

N14N16(28.0)

a (AzideRing)

15 2170 2162.78 2163.94 C12N14(23.6) s(FurancoseRing)

16 1887 1842.68 1949.16 C10H27(42.2)

C12N14(16.7)

C11C12(15.5)

s+ s+ s

(FurancoseRing)

17 1801 1811.70 1894.66 C5C7(21.7)

C3C5(15.7)

C3N4(10.7)

s+ s+ s

(ThymineRing)

18 1725 1728.36 1720.75 C3N4(19)C3O19(14.1)

s+ s(ThymineRing)

19 1623 1653.82 1605.83 C3N4(14.8)

C3O19(18.1)

a+ a(ThymineRing)

20 1552.48 1543.15 N4C5(24.1)

C5C7(15.6)

s+ s

(ThymineRing)

21 1554.01 1567.50 O15H31(50.3)

C13H29(11.5)

C13O15(11.1)

s+ s+ s

(HydroxylGroup)

22 1508.75 1489.23 C12N14(35.3)

N14N16(29.4)

s+ s

(AzideRing)

23 1483 1479.92 1472.42 C13O15(22.6)

C11C13(18.4)

C13H29(15.5)

a+ a+ a

(HydroxylGroup)

24 1476.10 1469.10 C7C8(25.7)

C1C7(15.0)

C5C7(13.2)

s+ s+ s

(ThymineRing)

25 1460.51 1451.15 C6H26(20.1)

C6C10(16.8)

C6H28(15.8)

s+ s+ s

(FurancoseRing)

26 1452.61 1431.28 N2H18(29.2)

N2C3(10.4)

s+ s

(ThymineRing)

27 1436.61 1419.17 C11C12(21.5) s(FurancoseRing)


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28 1414 1412.89 1429.43 C1C7(13.1)

C8H22(10.7)

N2H18(10.6)

s+ s+ s

(ThymineRing)

29 1395.64 1382.55 C6H28(12.5)

C6H26(12.4)

s+ s

(FurancoseRing)

30 1384.84 1377.64 C11H24(17.9) s(FurancoseRing)

31 1377.14 1370.14 C11H24(14.9) a(FurancoseRing)

32 1376.39 1364.90 C8H22(34.9)

C8H23(21.5)

U(ThymineRing)

33 1346.51 1332. C3O19(11.5) s(ThymineRing)

34 1324 1320.69 1330.35 C13H29(25.1)

C11C13(13.8)

s+ s

(HydroxylGroup)

35 1318.57 1316.84 C1N2(30.0)

C1O17(13.3)

C1C7(12.6)

s+ s+ s

(ThymineRing)

36 1286.42 1280.66 C5H20(28.1)

N2C3(12.7)

N4C5(11.7)

s+ s+ s

(ThymineRing)

37 1281.31 1278.95 C13H29(17.6)

C12N14(14.2)

s(HydroxylGroup)

s(AzideRing)

38 1275.97 1269.91 C6H28(23.8)

C13H29(22.6)

s (FurancoseRing)

s(HydroxylGroup)

39 1172.30 1174.33 C13H29(19.6)

C6H28(10.0)

a (FurancoseRing)

a(HydroxylGroup)

40 1151 1171.21 1169.71 C11H24(16.9)

C11C13(14.0)

s (FurancoseRing)

s(HydroxylGroup)

41 1118.52 1112.05 C11C13(18.9)

C11H24(17.8)

a (HydroxylGroup)

a(FurancoseRing)

42 1106 1103.83 1110.50 C5H20(22.5)

C1N2(14.4)

C3N4(14.3)

s+ s+ s(ThymineRing)

43 1072.51 1062.79 C8H23(36.6)

C8H21(21.0)

C8H22(17.3)

s+ s+ s

(ThymineRing)

44 1058.95 1049.28 C8H23(11.5)

C8H21(24.7)

C8H22(26.8)

a+ a+ a

(ThymineRing)

45 1050.84 1034.86 C6C10(19.5)

C10H27(10.6)

s+ s

(FurancoseRing)

46 1013 1012.02 1006.45 C6C10(18.6)

C6H26(17.2)

C6H28(15.9)

s+ s+ s

(FurancoseRing)

47 1001 966.26 976.38 C11H24(24.1)C11C12(19.2)

s+ s(FurancoseRing)

48 927 922.03 931.15 C1C7(12.9) s (ThymineRing)

49 854.58 863.26 C5C7(13.6) a(ThymineRing)

50 694.90 715.21 C6C10(11.0) s(FurancoseRing)

51 574 574.24 562.87 C13O15(18.7)

C11C13(16.2)

rocking

(HydroxylGroup)


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52 482 490.62 450.83 C1C7(10.5) s(ThymineRing)

53 452.03 436.16 O15H31(22.4)

C11C13(18.9)

s + s

(HydroxylGroup)

54 430.13 426.19 N14N16(11.8) s(AzideGroup)

55 367.44 354.55 C3015(37.0) s(HydroxylGroup)

56 319.41 342.60 N14N16(21.9) a(AzideGroup)

57 311 305.67 317.91 C6C10(14.5)

C6H28(21.1)

C6H26(18.9)

s+ s+ s

(FurancoseRing)

58 236.18 225.89 C6C10(24.5)

C6H28(20.1)

C6H26(19.9)

a+ a+ a

(FurancoseRing)

59 144.79 15.47 C6C10(13.4)

C10H27(13.0)

s+ s

(FurancoseRing)

60 112.24 77.84 C7C8(24.5)

C8H21(21.2)

C8H22(20.5)

a+ a

(ThymineRing)

S.N. Experimental

Frequencies

(incm1)

CalculatedFrequencies(incm1)

Vibrational

Assignments

HF DFT(B3LYP) AtomPair/Energy

Contribution(in%)

Species a

1 1387 1397.07 1390.55 C8H21(47.9)

C8H23(35.4)

s (ThymineRing)

2 1350.60 1363.73 C6H28(17.3)

C6H26(15.0)

s(FurancoseRing)

3 1246.77 1274.74 C13H29(54.1)

O15H31(12.7)

s +s(Hydroxyl

Group)

4 1191 1213.16 1206.15 C6H26(27.1)

C10H27(11.8)

C13H29(11.8)

a (FurancoseRing)

a(HydroxylGroup)

5 914 944.84 981.27 C5H20(65.0) s (ThymineGroup)

6 857.71 885.26 C6C10(11.9) s (FurancoseRing)

7 817 821.85 828.62 C10H27(24.8)

C6H26(13.9)

C6H28(13.7)

s (Furancosering)

8 741 752.51 797.30 C1C7(31.7)

C1N2(21.6)

C1O17(21.5)

s (ThymineGroup)

9 696.64 699.38 C3N4(27.3)

N2C3(21.3)

C3O19(20.8)

s (ThymineGroup)

10 689.62 676...33 N2H18(80.2) s (ThymineGroup)

11 607 624.34 647.93 C1N2(21.1)

N2C3(14.8)

C1C7(13.8)

a (ThymineGroup)

12 563.95 562.70 C3C5(14.5) Rocking(Thymine

Ring)

13 537.38 555.47 C6C10(11.6) a(FurancoseRing)


12/12

14 486.23 489.36 C11H24(11.3) s Scissoring

(FurancoseRing)

15 461.91 453.46 C12N14(12.0)

C11C12(10.2)

aScissoring

(FurancoseRing)

16 441 442.68 439.89 N16N32(52.0)

N14N16(41.6)

s (AzideRing)

17 406 417.29 410.12 N14N16(11.8) aScissoring

(AzideRing)

18 355 364.19 389.32 O15H31(21.8)

N14N16(13.2)

s(HydroxylGroup)

s(AzideRing)

19 337.41 377.95 C7C8(20.5)

N4C5(13.0)

s(ThymineRing)

20 180.47 191.89 O9C110(12.1)

O9C11(11.4)

s(FurancoseRing)

21 167.09 183.81 C1N2(20.3)

N2C3(20.0)

N2H18(17.7)

a(ThymineRing)

22 106.61 116.5 C11C12(21.4)

C11C13(20.6)C11H24(18.8)

s(FurancoseRing)

23 81.07 71.33 C3O19(13.6) s(ThymineRing)

24 50.97 47.41 C13O15(19.0)

C11C13(16.2)

O15H31(11.9)

a(HydroxylGroup)

25 38.55 33.11 C13O15(17.5)

C11C13(12.9)

Rocking

(HydroxylGroup)

26 29.21 27.21 C7C1(19.8)

C7C5(17.3)

C7C8(12.6)

Rocking

(ThymineRing)

27 28.56 26.8 C10O9(18.6)

C10C6(16.5)

C10H27(12.9)

Rocking

(AzideRing)

28 17.86 18.42 C8H21(15.6)C8H23(14.9)

C8C7(11.60

Rocking(ThymineRing)

29 12.50 13.6 Twisting

30 10.10 10.8 Twisting

aOnlycontributions>10%arelistedb =stretching,=inplanebending, =outofplanebending,s=symmetric, a= asymmetric

Experimental Theoretical HF DFT 3'-Azido-2'-Deoxythymidine

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Transcript of Experimental Theoretical HF DFT 3'-Azido-2'-Deoxythymidine