Mital, H P

Rastogi, V K

Sharma, S N

IACS Institutional Repository

Ind ian  J. Phys. M B  (4), 312-316 (1990)Laser Raman and infrared spectra of some uracil derivatives*V  K R astog i, H  P Mital*^ and S N Sharma*^^Department of Physics, Lajpat Rai College, Sahibabad-201 005, IndiaReceived 6 November 1989, accepted 25 Aprii 1990The N -h etero cyc lic  m olecules e .g . p yrim id in e , cytosine, uracil and the ir derivatives  are o f considerab le  b io lo g ic a l and pharm aceutical im portance (H andschum acher and W e lch  1 9 6 0 , M a rtin  1 9 6 1 ). Recent spectroscopic studies o f th e re  com pourids  have been m o tiva ted  because th e  v ib ra tio n a l spectra o f free base m o lecu les  \is  very useful for th e  understanding o f specific  b io lo g ica l processes and in the  analysis o f re la tive ly  com plex system s. A lo n g  th e  m acrom olecular d o u b le -h e lix  chain , th e  v ib ra tio n a l m odes o f each base in teract w ith  those o f o th e r bases th rough  hydrogen bonds or stacking  effects  and these in teractions affect th e  ring  vib ra tio n s . The v ib ra tio n a l spectra o f various nucle ic  acid  co n s titu e n ts  inc lud ing  uracil have been stud ied  in d e ta il (A ngel 1 9 6 1 , Lord and Thom as 1 9 6 7 , Susi and A rd  1 9 7 1 , Susi et ol 1 9 7 3 , Bandekar and Zundel 1 983 , S in g h  et al 1 9 8 7 ), b u t very  li t t le  w o rk  on th e  v ib ra tio n a l spectra o f d e riva tives  o f u rac il has ^been done  (S h im an o u ch i ct al 1 9 6 4 , Sanyal et al 1 9 7 7 , Ferro et a / 1 980 , G oel et ol 1981 , A runa and S hanm ugam  1 9 8 5 , Y adav et al 1 9 8 8 ). In o rder to  extend  th is  s tudy  fu rther, w e  have recorded th e  IR and laser Raman spectra o f 5 -c h lo ro  and 5 -a m in o  uracils  fo r th e  f irs t tim e  and assigned th e  observed fundam ental bands.Pure so lid  sam ples o f 5 -ch lo ro u rac il (m p >  3 0 0  C ) and 5 -am in ou rac il (m p > 3 0 0  ’C ) w e re  o b ta in ed  from  M /S  S ig m a C hem ical C o, U S A  and used as such w ith o u t  fu rther p u rifica tio n . The IR absorption  spectra have been recorded on Beckm an  IR -1 2  spectrophotom eter in KBr pe lle t in th e  region 4 0 0 -4 0 0 0  c m ~ *. The laser Ram an spectra in th e  reg ion  5 0 -2 0 0 0  c m ~ ’ (Ram an spectra beyond 2 0 0 0  cm ”  ^ are  not w o rth -m e n tio n in g ) have been recorded on a Spex spectrophotom eter using  A rg o n  laser source w ith  exc itin g  rad ia tions 5 1 4 5  A .''Department of Physics, Meerut College, Meerut-250 001, India.'"Indian Institute of Petroleum, Dehradun-248 005.*Presented at International Conference on Raman»Spectroscopy, lACS, Calcutta. Nov. 2-7, 1988.312Laser Raman and Infrared spectra of some uracil derittatlves 313Figures 1 -3  show  the structures o f the uracil and 5 -ch lo ro  and 5-am ino  uracils m olecules w ith  classical numbering o f the atom s respectively. The  vibrational spectra (IR  and Raman) have been interpreted assuming planar geom etry  and C , point group sym m etry for both the molecules and the observed fundam entals  have been assigned to  d ifferent normal modes of v ibration. The vibrational modes are classified as transform ing like the basis functions o f the o ' and a" irreducible  representations. Thus the 30  fundam ental modes o f 5-chlorouracil may be classified  in to  2 1 a ' sym m etry species (in -p lane) and 9a" species (ou t-o f-p lane) and in!  HFigure I. Uracil.NFigure 2. 5-Chlorouracil.the case of 5-am in ou rac il, the 36  fundam ental modes may be classified into  2 5 o 'a n d  11a" sym m etry species. The analysis o f the bands and the assignment of the fundam ental frequencies are m ade on the basis of m agnitude and relative  intensities of the observed bands and help has been taken from  the assignments made by earlier w orkers in the sim ilar molecules. The wavenum bers o f the observed fundam ental bands in IR and Raman spectra a lo n g w ith  the proposed assignments are given in Table  1.The frequencies due to  C H /N H  stretching modes are w e ll separated from  the frequencies due to  other modes. The molecules under study contain only  one hydrogen atom  attached to the carbon atom o f the ring (Figures 2 and 3 )  and thus involve only one C - H  valence oscillation w h ich  have been identified  at 3 0 3 2  and 3 0 1 8  cm"^ in the IR spectra o f the 5 -ch lo ro  and 5-am ino  uracils respec­tive ly . These assignments are in agreement w ith  those proposed by Ferro et al(1 9 8 0 ) and A runa and Shanmugam (1 9 8 5 ) in the case o f related molecules. The bands observed at 1422 cm~^ (IR ) and 1410 cm "’ (Raman) in the case o f 5-chlorouracil and at 1425 c m " ’  in 5-am inouracil have been assigned to  C  -  H in­plane bending mode.The N - H  stretching w as  assigned by Susi and A rd (1 9 7 1 ) at 3 1 4 5  c m " ’  in 1-m ethyl uracil and at 3 1 4 6  c m " ’  in 1-m ethyl thym ine and by Sanyal et al (1 9 7 7 )  at 3 1 7 8 , 3 0 9 8  c m " ’  in 5-b rom ouracil, at 3 1 8 8 , 3 1 2 8  c m "’  in 5 -m e ih y l uracil and at 3 1 7 8 , 3 1 0 7  c m "’  in 4 (6 )-a m in o u ra c il. In the present case only one o f the  tw o  N - H  stretching m odes could  be observed at 3 0 5 9  and 3 0 8 0  c m " ’  in the IR spectra o f 5 -ch lo ro  and 5 -am in o  uracils respectively.The N H , group has tw o  ( N - H )  stretching frequencies, one being s y r o ^ r ic  and othe. asymmanic. The frequency of asyreinetrlc yibretion re h.ghet than that ofT.bl« I. Assiflnment ol fundemontal frequencies (in cm -) of 5-chloro and 5-amino uracils. _______________314 V K Roitogi H P Mital and 5 N Shormo5-Chloro-uracil5-Amino- Symmetry_____________ speciesIB RamanAssignment— 3370 — o'___ 3295 — o'3059 3080 — o'3032 3018 — o'o'1705 — 1740 ■1677 1676 1672 — o'1632 1625 1615 1645 o'— 1588 — a '1560 1556 — a '1542 1541 — a '1509 — 1506 1493 a '1456 1473 1462 o '1440 - — 01422 1410 1425 — a '_ 1387 1400 a '1340 1339 - 1334 o '_ 1276 — o '_ 1245 1251 o '1230 — 1212 1215 o '___ 1108 — a '1090 1077 — a '1008 — 1016 — o '880 ,— o '781 784 — — a '742 734 — 0680 668 — a '___ 639 — — o'610 618 — — o'542 548 552 — o'946 — — a"865 — 863 — a"815 — 805 — o"756 — 767 — o"— 749 — o"___ 488 — o"445 — 438 — o"428 — — o"N H.; asymmetric stretch NHa symmetric stretch N H stretch C H stretch C  ^0 stretch C 0 stretch C -C stretch ;NHa scissorN ' H in-plane bending 'N -H  in-plane bending C - N stretch C - N stretch ring stretchC -H  in-plane bending NHtt rock ring stretch C' NHa stretch NHa rock ring stretch NH* twisting ring stretch ring in-plane bending C N in-plane bending C - Cl stretch C O in-plane bending ring in-plane bending C -O  in-plane bending C - Cl in-plane bending ring in-plane bending N H out-of-plane bending N -H  out-of‘plane bending C -H  out-of-plane bending ring out-of-plane bending NHa wagging NHa torsionC  ^0  out-of-plane bending ring out-of-plane bendingTable I. (Contd.)Loser Ramon and infrared spectra of some urocll derivatives 3155-Chlofo-uracilIR Raman IR5-Amino-ura<^__RamanSymmetryspecies Assignment4122344201411251019078418134100C -0  out-of-plane bendingC N out-of-plane bendinglatticelatticelatticelatticelatticesym m etric  one. The N H g  asym m etric  stretch m odes have been id en tified  a t 3 3 7 0  and 3 2 9 5  cm~^ respectively  in the IR  spectrum  o f 5 -am in o u rac il in conform a­tio n  w ith  th e  assignm ents proposed by A runa and Shanm ugam  (1 9 8 5 ) fo r 6 -a m in o -2 -th io u ra c il.The neutral fo rm  o f u rac il and its  substitu ted  derivatives have three double  bonds and th e ir stretching v ib ra tio n  are expected to  g ive  rise to  three strong  in frared bands in th e  region 1 5 0 0 -1 7 0 0  cm ~^. O u t o f the th ree , tw o  strong bands at 1 7 0 5  and 1677  cm "  ^ in  th e  IR  spectrum  o f 5-ch lo rourac il and at 1740  and  1672  cm "^ in th e  IR  spectrum  o f 5 -am in ou rac il are assigned to  th e  t w o C  =  0  stretch ing  fundam enta ls . N o  such v ib ra tio n  w a s  observed in th e  Raman spectrum  of 5 -am in o u rac il, w hereas  one o f these m odes could  be observed a t 1676  cm"*^ in the Ram an spectrum  o f 5 -c h lo ro u ra c il. The  th ird  v ib ra tio n  a t 1632  and 1625  cm "»  in th e  IR  and Ram an spectra, respectively, o f 5 -ch lo ro u rac il and at 1615  and  1645  cm " 1 in  th e  IR  and Ram an spectra respectively  o f 5 -am in o u rac il have been associated w ith  C = C  stretching v ib ra tio n . These assignm ents are in agreem ent w ith  those ava ilab le  for u racil, (S u s i and A rd  1 9 7 1 ), and mono and d isu b s titu ted  uracil (S anyal « al 1 9 7 7 ). In  th e  IR  spectra o f 5 -ch lo ro u rac il, th e  1677  cm "^  band appears to  be a c losely spaced d o u b le t. Th is  sp littin g  m ay be due to  crystal fie ld  e ffec t as suggested by Sanyal et al (1 9 7 7 ) . The  space group o f th e  5-ch lo ro u rac il crystal is P 2 i/c , w ith  a = 8 .4 5 0 ,  b = 6 .8 8 6 ,  c - 1 1 .4 1 9  A  and  )3 1 2 3 .9 3  .The N H g  group  has scissoring, rocking, tw is tin g  and w ag g in g  m odes o f bending v ib ra tio n s . The bands observed a t 1588 , 1387  and 1108  and 7 4 9  c m " ‘  in  IR spectrum  o f 5 -am in o u rac il have been assigned as scissoring, rocking, tw is tin g  and w a g g in g  rrKfdes respectively. The  band observed at 1400  cm~^ in Raman  spectrum o f 5 -am in o u rac il has been assigned to  N H ,  rocking m ode. These assign­ments fin d  support from  th e  w o rks  o f A ru na  and Shanm ugam  (1 9 8 5 ) .The N -  H  in -p lane bending v ib ra tio n s  have been id en tified  at 1 5 0 8  and  1417 cm "^ in u rac il (S h im an o u ch i et al 1 9 6 4 ), a t 1 590 , 1 5 2 5  cm "^ in  6 -a m in o -316 V K RastogI H P M ita l and S N Sharmauraoil and at 1550 , 1510  c m " ’ in 6 -am ino-2-th iouraG H  (A ru n a  and Shanm ugam  1 9 8 5 ). In  consonance w ith  these assignnnents th e  bands observed at 1660 , 1542  cm "^ in the IR spectrum  o f 5 -ch lo ro u rac il and at 1 5 5 6 , 1541 cm~^ in th e  IR  spectrum  o f 5 -am in ou rac il have been id en tified  as N - H  in -p lane bending v ib ration . T h e N  - H  o u t-o f-p la n e  bending v ib ratio n s have been id en tified  at 8 6 5  and 9 4 6  cm"'^ in th e  IR spectrum  o f 5 -ch lo ro u rac il and at 8 6 3  c m " ‘  in th e  IR  spectrum  o f 5 -am in ou rac il.The C =  0  in -p lane  bending v ib ra tio n  cou ld  on ly  be observed in 5-ch lo rouracil at 7 4 2  cm “  ^ in the IR  spectrum  and at 7 3 4  and 6 3 9  cm "^ in th e  Raman spectrum . The C = = 0  o u t-o f-p la n e  bending m odes could  be id en tified  a t 4 4 5  and 4 1 2  cm~^ in th e  IR spectrum  and a t 4 2 0  cm"  ^ in th e  Raman spectrum  o f 5 -ch lo ro u rac il and at 4 3 8  and 4 1 8  cm "^ in th e  IR  spectrum  o f 5 -am in o u rac il.The ring o u t-o f-p la n e  bending m odes have been observed at 7 5 6  and 4 2 8  cm"*^ in 5 -ch lo ro u rac il and at 7 6 7  cm "^ in 5 -am in o u rac il.B e lo w  2 0 0  c m ~ ' five  lines in th e  Raman spectrum  o f 5 -ch lo ro u rac il and tw o  lines in the Raman spectrum  o f 5 -am in o u rac il have been observed, w h ic h  are', in a region w h ere  la ttic e  m odes associated w ith  C =  0  - H — N hydrogen bonds^ are expected.A c k n o w le d g m e n tsThe authors are thankfu l to  Prof P S N araynan, lIS c , B angalore for p rov id ing  necessary fa c ilitie s  fo r recording laser Raman spectra and to  U G C , N e w  D elh i for provid ing  financial assistance.nReferencesAngel C J L 1961 J. Chem, Soc. 504Aruna S and Shanmugam G 1985 S p e c t r o c h i m  A c t a  38A 815 Bandokar Jand Jundel G 1982 S p e c t r a  C h i m .  Acta 3BA 815 Bandekar J and Zundei G 1983 S p e c t r o c h i m .  A c t a  39A 343 Ferro D, Bencivenm L, Teghil R and Pelino M 1980J, I n d i a n  C h e m .  Soc. 57  626 Goal R K, Gupta S K, Agarwal M L and Sharma S N 1981 I n d i a n  J .  P u r e  A p p l .  P h y s . 19 501 Handschumacher R E and Welch A D 1960 The Nuc/eic Acids Vol 4 (New York; Academic Press) 453Lord R C and Thomas G J (Jr) 1967 S p e c t r o c h i m .  A c t a  23A 2551 Martin G T 1961 B i o l o g i c a l  A n t a g o n i s m  (New York Blakiston)Rastogi V K, Mital H P and Sharma S N 1988 P ro c .  I n t e r n a t i o n a l  C o n f e r e n c e  on  R a m a n  S p e c t r o ­s c o p y  and Sons London (New York •. John Wiley) p 87 Sanyal N K, Srivastava S L and Goel R K 1977 I n d i a n ] .  Ph ys . 52B 108Shimanoucni T, Tsuboi M and Kyogobu 1964 Adv. Chem. P h ys . (New York : Intersciance) 7p435Singh B, Khan Sawar Akram and Uday Bhanu 1987 I n d i a n  J .  C h e m .  26A 1066 Susi H and Ard J S 1971 S p e c t r o c h i m .  A c t a  2 7 A  1549 Susi Hr Ard J S and Purcel J M 1973 S p e c t r o c h i m .  A c t a  29A 725 Yadav R A, Yadav P N S and Yadav J S 1988 P r o c .  I n d i a n  A c a d .  Sc/. 100 69

Laser Raman and Infrared Spectra of Some Uracil Derivatives

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Laser Raman and Infrared Spectra of Some Uracil Derivatives

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