Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 4(4), 12-16, April (2014) Res. J. Chem. Sci. International Science Congress Association        
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Fragmentations processes of3-coumarinyl carboxylates in ESI / MS and their Correlation with the Electronic charges of their atomsJules Yoda, Thierry Chiavassa and Adama Saba1* Laboratoire de Chimie Moléculaire et des Matériaux, Université de Ouagadougou, BURKINA FASO Laboratoire de Physique des Interactions Ioniques et Moléculaires, université de Provence, Marseille, FRANCE Available online at: 
www.isca.in, www.isca.me
Received 13th January 2014, revised 10th February2014, accepted  24th March 2014Abstract 3-coumarinyl carboxylates are 3-hydroxyl-coumarin derivatives obtained by O-acylated. In this work, we have studied thecorrelation between electronic charges of atoms and the fragmentation processes of these compounds.. The method has been successfully applied many times for EIMS, but only one time for ESI/MS. In this paper, we would like to apply the method to the ESI/MS spectra of another sery of 3-coumarinyl carboxylates. Good correlations was obtained. Keywords: 3-coumrinyl carboxylate, ESI/MS, fragmentations, Electronic charge. IntroductionNatural or synthetic coumarin derivatives are of great interest, since many of them show several important properties1-9. Furthermore, coumarins derivatives are well-known fluorescent dyes7-11 and high photoluminescent compounds12. They have been intensively investigated because of their biologic properties. So they have been identified as anticoagulant, antibiotic, antiviral, cytotoxic9,11 and herbicides compounds. Additionally, coumarin derivatives are widely used as food, perfumes and cosmetic. complements10,13. Most of their spectra (UV-Visible, IR, MNR and Mass) have also been reported14,15. Literature shows that the mass spectra study in correlation with electronic charges of atoms has already been described. So, the correlation between the fragmentation processes in EIMS and the electronic charges of atoms of some monosubstituted and disubstituted coumarins have been reported16-18. The method has been applied only one time to ESI/MS. It has been successfully applied both on EIMS19 and ESI/MS of 4-acyl isochroman-1, 3-diones20. The electronic charges of the atoms were performed by AM1 semi empirical method20. It has been found that fragmentations processes in eims take place generaly at the level of atoms bearing high negative charge. Nevertheless, in positive mode ESI/MS, fragmentations are guided by the atoms bearing high positive charge.  So, in Mass Spectrometry, the fragmentations are most often obtained at the level of atoms exhibiting the same type of charge than the ionization projectile. In EIMS the atom must bear a high positive charge, but a high negative charge in ESI/MS. So, it would be possible to predict and explain most of the behavior of organic compounds in mass spectrometry by using electronic charges of atoms. In this paper, we should like to apply the method using the electronic charges of atoms in the study of the fragmentations of title compounds in ESI/MS. Interesting results have been obtained. Material and MethodsPreparation of 3-coumarinyl carboxylates 1: The method used for the synthesis of compounds  have been early described for 4-acyl isochroman-1,3-diones21. Thus, action of acid chlorides or acid anhydrides on 3-hydroxycoumarin in the presence of an appropriated base, lead to give compounds , with more than 60% yield (scheme-1). They have been identified by IR, H and 13C NMR spectra. 
O
O
H
O
+CO
Solvent
O
O
O
O
R
X
R
Scheme-1 Synthesis of 3-coumarinyl carboxylates 1 X = Cl or OCOR,  B = Pyridine (py) or Triethylamine (EtN). 1a : R = CH3 ; 1b : R = C ; 1c : R = C ; 1d : R = -ClC4 ; 1e : R = -NO ; 1f : R = -CNC4 ; 1g : R= -MeOC4 ; 1h : R = 3,5-(NO. Recording spectra: ESI/MS spectra, described in the below table 1 have been recorded on a 3200 QTRAP (Applied Biosystems SCIEX) mass spectrometer apparatus equipped with an atmospheric pression ionization source (API). The sample is dissolved in 450mL of dichloromethane and diluted at 1/100 in a 3mM methanolic solution of ammonium acetate. It is then ionized in positive electrospray mode in the following conditions: electrospray tension (ISV): 5500V; Orifice tension (OR): 20V; pression of nebulisation gas (air): 20psi; debit: 10µL/min. The fragmentation spectra are obtained after dissociation induced by collision; collision gas is N2 ; energy of collision 20eV; two quadripôles tandem mass analysers. Results are reported in the tables 1. AM1 Calculation of electronic charges: Electronic charges of atoms have been obtained by Austin Model 1 semi empirical method22 with a “Chem3D Ultra 8” software, A “Pentium 4” computer has been used. Results are reported in tables 2, 3, 4 and 5. 
Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(4), 12-16, April (2014) Res. J. Chem. Sci.   International Science Congress Association 
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Table-1 ESI/Mass Spectra of compounds 1
1aR = CH
3
 
1bR = C
2
H
5
 
1cR = C
6
H
5
 
1dR =-ClC
6
H
4
 
m/z % m/z % m/z % m/z % 
205[MH]
+
 
100 219[MH]
+
 
89.33 267[MH]
+
 
29.33 301/303[MH]
+                                
40 
163 53,33 163 100 105 100 
139/ 141                               
100 
- 57 53.33 - - 
Table-2 Electronics charges (carbon) 1e  R = NO
2
C
6
H
4
 
1fR = pCNC
6
H
4
 
1gR = MeOC
6
H
4
 
1hR= (NO
2
)
2
C
6
H
3
 
m/z % m/z %
 
m/z %
 
m/z %
 
312[MH]
+
 
58.66 292[MH]
+
 
31,81 297[MH]
+
 
13,33 357[MH]
+
                              
100 
285 100 130 100 
135                                      
100 
295                    
58,66 
- - - - 
Table-3 Electronics charges (carbon) R C
2
 C
3
 C
4
 C
5
 C
6
 C
7
 C
8
 
CH
3
 
0.3937 -0.0332 -0.1480 -0.1249 -0.2183 0.1455 -0.2012 
CH
3
CH
2
 
0.3993 -0.0392 -0.0920 -0.12554 -0.2179 -0.1477 -0.2003 
C
6
H
5
 
0.3916 -0.0258 -0.8525 -0.1262 -0.2185 -0.1461 -0.2010 
-ClC
6
H
4
 
0.3982 -0.0347 -0.0908 -0.1268 -0.2154 -0.1473 0.1997 
-NO
2
C
6
H
4
 
0.3395 0.1613 -0.1275 -0.1282 -0.1931 -0.0404 -0.2281 
-CNC
6
H
4
 
0.3829 -0.0254 -0.1193 -0.1306 -0.2117 -0.1472 -0.1964 
-MeOC
6
H
4
 
0.3746 -0.1721 -0.1286 -0.1320 -0.2101 -0.1513 -0.1958 
3,5-(NO
2
)
2
C
6
H
3
 
0.3029 0.3001 -0.1512 -0.1234 -0.1625 0.0991 -0.2487 
Table-4 Electronics charges (carbon) R C
9
 C
10
 C
11
 C
12
 C
13
 C
14
 C
15
 
CH
 
3
 
0.1088 -0.0798 0.3516 -0.3930 - - - 
CH
3
CH
2
 
-0.1031 -0.1426 0.3527 -0,2647 -0.3522 - - 
C
6
H
5
 
0.1094 -0.1480 0.4092 -0.1323 -0.1236 -0.2110 -0.1565 
-ClC
6
H
4
 
0.1082 0.1399 0.4053 -0.1223 -0.1169 -0.1242 -0.0526 
-NO
2
C
6
H
4
 
0.1676 -0.0744 0.4281 -0.1245 -0.1382 -0.1193 -0.0721 
-CNC
6
H
4
 
-0.0956 -0.1278 0.4071 -0.0974 -0.1244 -0.1686 0.0132 
-MeOC
6
H
4
 
0.0876 -0.1178 0.4261 -0.1627 -0.0854 -0.2867 -0.1274 
3,5-(NO
2
)
2
C
6
H
3
 
0.18548 0.0460 0.3912 -0.1810 -0.0186 -0.0667 -0.0019 
Table-5 Electronics charges (carbon) R C
16
 C
17
 O
1
 O
2
 O
3
 O
4
 
CH
3
 
- - -0.2281 -0.3029 -0.2635 -0.3542 
CH
3
CH
2
 
- - -0.2292 -0.2997 -0.2552 -0.3625 
C
6
H
5
 
-0.2090 -0.1272 -0.2274 -0.2988 -0.2628 -0.3515 
-ClC
6
H
4
 
-0.1968 -0.1965 -0.2214 -0.2971 -0.3595 -0.2485 
-NO
2
C
6
H
4
 
-0.1419 -0.1267 -0.1816 -0.1681 -0.2441 -0.2636 
-CNC
6
H
4
 
-0.1699 -0.1443 -0.1837 -0.3202 -0.2274 -0.3488 
-MeOC
6
H
4
 
-0.2314 0.0896 -0.2015 -0.1897 -0.3169 -0.34280 
3,5-(NO
2
)
2
C
6
H
3
 
-0.0648 -0.0571 -0.0968 -0.0721 -0.1369 -0.2109 
Table-6 Charge of atoms of substituent X       X Cl N C O O 
N 
O 
O 
      Cl -0,00890
 
- - - - 
- 
- 
- 
    
NO
2
 
- 0.5190 - -0.3177 -0.3117 
- 
- 
- 
     CN - - -0.0731 - -0.0644 
- 
- 
- 
OCH
3
 
- - 0.2015 -0.2477 - 
- 
- 
- 
(NO
2
)
2
 
- 0.3927 - -0.3168 -0.2293 
0.3958 
-0.2539 
-0.2688 
Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(4), 12-16, April (2014) Res. J. Chem. Sci.   International Science Congress Association 
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Results and DiscussionModes of fragmentations: In the hydrocarbon skeleton of compounds , it is notable that only the two atoms of carbon, Cand C11, present a high positive charge. This could explain the small number of fragmentations. So, only two kinds of fragmentations have been obtained for each compound. In the early studies, the same results have been obtained and it has been found that the fragmentations processes are directed by the atoms exhibiting the same type of charge than the one of ionization projectile. So, in positive mode ESI/MS of the compounds , only these two carbons would guide the fragmentations19. Fragmentations of compounds 1 in ESI-MS: Formation of the pseudo molecular ion [MH]. The pseudo molecular ion [MH]+ has been described to be obtained by the reaction shown in the below scheme 2.  It is remarkable that the formation of this ion is obtained at the level of heteroatom under SP hybridization (O and O). This can be explain by the easiest mobility of p electrons doublets and their best ability to react with acids (scheme 2)19. 
O
O
O
O
R
H
O
O
H
O
R
O
O
H
O
O
R
O
1a : R = CH, MH =205 ; 1b : R = C, MH = 219 ; 1c : R = C, MH = 267; 1d : R = -ClC, MH = 301/303 ; 1e : R = -NO, MH = 312 ; 1f : R = -NC, MH = 292 ; 1g : R = -CHOC, MH = 297 ; 1h : R = 3,5-(NO, MH = 358 Scheme-2 Formation of pseudo molecular ions A and B Formation of acyliumion: The pseudo molecular ion A described in scheme 2, leads to the formation of acylium fragment as shown in the below scheme 3. 
O
C
O
R
O
H
O
O
H
O
RC
O
RC
O
RC
O
Ion acylium
Scheme-3 Formation of ion acylium 1b: R = C, m/z = 57; 1c : R = C, m/z = 105 ; 1d : R = ClC, m/z = 139/141 ; 1e : R = -NO, m/z = 150 ; 1f : R = -CNC, m/z = 130 ; 1g : R = -CHOC, m/z = 135; 1h: R = 3,5-(NO, m/z = 196. This fragmentation has been guided by the carbon C11, which is highly positively charged. This result is in accordance with the early results17-20, which stipulated that “the fragmentations processes take place at the level of atoms bearing the same type of charge as the projectile particle used for ionization”. For ESI/MS of compounds , these atoms are C2 and C11. Surprisingly, it is notable to observe that the compound 1a (R = CH) does not present this fragment. Due to the very high negative charge of its carbon C12 (-0.3930), the most high negative charge of this compound, this carbon C12 could equilibrate the charge of C11 (+0.3516) and obstruct this fragmentation. For the other compounds, this situation does not exist. An atypical fragmentation: It has been observed that when R is a methyl moiety (R = CH), the acylium cation is not formed. It has been obtained on behalf of this acylium cation, an atypical fragmentation, not only for this compound 1a, but for 1b   (R = ) too. In both the cases when R is an aliphatic moiety, it is produced a fragment with m/z = 163Da. This fragmentation could take place by the lost of a neutral ketene molecule (R-CH=C=O). It is possible to explain this fragmentation by the follow scheme 4, from the pseudo molecular ion A. Considering the high positive charge of atoms C and C11, which can guide the process, it is reasonable to admit the follow mechanism, shown in the scheme 4 for the formation of this fragment. 
O
O
O
O
R
H
H
Rotation
O
O
O
C
C
O
R
H
H
O
OH
OH
H
H
+CC
H
R
O
O
OH
OH
R = H or CHScheme-4 Process of formation of the fragment m/z = 163 This fragmentation, initiated by C, leads to give a particularly stable cation as the 2,3-dihydroxy-1-benzopyrylium cation. The compounds with an aromatic moiety are not able to give this cation, due to the absence of a removable hydrogen on their carbon C12. When R is an aliphatic moiety, this hydrogen has an acidic character due to its  position from a carbonyl group (C11). Moreover, due to its initiation by C, this fragmentation could take place when R is all type of aliphatic moiety bearing at least, one atom of hydrogen on its C12. ConclusionIn positive mode ESI/MS, the fragmentation of molecular ions [MH] of organic compounds takes place more often, at the level of the elements with a significant positive charge, as Cand C11 for the title compounds . As observed in the table of 
Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(4), 12-16, April (2014) Res. J. Chem. Sci.   International Science Congress Association 
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electronic charges of atoms, the compounds  contain only two high positively charged atoms that strongly influence their fragmentations. The small numbers of fragmentations in positive mode ESI-MS could thus be explained through the reduced number of high positively charged atoms. In this study, we found, one more time, that there is a relationship between  the nature of the charge of the projectile used to obtain the ionization and the nature of the charge of atoms which orientate the fragmentation processes. These charges must have the same nature. This relationship could orientate the research of fragmentations processes. So, the way for explaining and predicting fragmentations processes in mass spectrometry by using the electronic charges of atoms of the hydrocarbon skeleton of organic compounds seemed to be really open. Acknowledgements  We are gratefull to Pr. Dr. Gerald HENKEL from University of Paderborn (Germany) for supplying reagents and Valérie Monnier from spectropole of université de Marseille (France) for recording ESI Mass spectra. References1.Abernethy J.L., The historical and current interest in coumarin, J. Chem. Educ, 46, 561 and 856 (1969) 2.Murray R.D.H., Mendez .J., Brown. S.A, the natural coumarins: occurrence, chemistry and Biochemistry, Wiley & Sons New York, NY, USA (1982) 3.Hassan A. Ewais, Abdulla M. Asiri, Iqbal M .I. Ismail Salem A. Hameed and Ahmed A. Abel-Khalek, Kinetics and Mechanism of the ring opening of 3-carboethoxycoumarin  by sodium hydroxide  and hydrazine, Murray, Research journalof Chemical Sciences, 2(12), 57-64 (2012)4.Levine W.G., In the pharmacological basis of therapeutics. 5th ed. Goodman L. S. and Gilman A., MacMillan, New York (1975) 5.O’Reilley R.A., Vitamin K and the oral anticoagulant drugs, Annu Rev. Med., 27, 245-261 (1976)6.Silverman R.B., Model studies for a molecular mechanism of action of oral anticoagulants, J. Am. Chem. Sco., 103, 3910-3915 (1981) 7.(a) Kim S.H., Jung E. J., SO E. M., Shen C. Z., Schun H. J., Kim Y.M., Kim I. K.,Enhanced Electrochemiflorescence and reduction mechanism of acetoxy coumarin derivatives in acetonitrile solution, Bull. Korean Chem. Sco., 27, 1329 (2006) (b) Roh S.–G., Baek M. S., Hong K.–S., Kim H. K., Synthesis and photophysical properties of luminescent lanthanide complexes based on coumarin-3-carboxylic acid for advanced photonic applications, Bull. Korean chem. Soc., 25, 343 (2004) 8.(a)Zahradnik M., The Production and Application of Fluorescent Brightening Agents, Wiley & Sons, 1992)  (b). Maeda, Laser Dyes, Academic Press, New York, 1994) 9.Stefanou V., Matriadis D., MelagraKi G., Afantitis A., Athanasellis G., Igglessi-Markopoulou O.,Vickie McKee and John Markopoulos Functionalized 4-hydroxy coumarins: Novel synthesis, crystal structure and DFT calculations, molecules, 16, 384-402 (2011) 10.Vijila C., Ramalingan A., Palanisamy P.K. and Masilmani V., Role of dipole moment of solvent in formation and stabilization of the tict states in coumarin 445 under nitrogen laser excitation, Spectrochimical acta part A, 57, 491-497 (2001)11.Ramegouda M., Change in energy of hydrogen bonds upon excitation of coumarin 1: TDDFT/EFP1 method, Research journalof Chemical Sciences, 3(7), 27-30 (2013)12.Su-Jin Park, Jong-Cheol Lee, and Kee-In Lee, A facile synthesis of 4-hydroxycoumarin and 4-Hydroxy-2-quinolone derivatives, Bull. Korean Chem.Sco., 28(7),1203-1205 (2007)13.Carboni S., Maloguzzi V., Marzili A., Ferulend a new coumarin derivative form ferula commis, Tetrahedron Lett., , 2763-2785 (1964)14.Trimèche B., Gharbi K., Romdhane A., Hammami S., Mighri S. A.Z ., Synthèse et étude de la réactivité d’un nouveau dérivé 4-oxocoumarinique, journal de la société chimique de Tunisie, 11, 91-99 (2009)15.Traven V. F., Negrebetsky V. V., Vorobjeva L. I. and Carberry E. A, Keto-enol tautomerism,NMR spectra, and H-D exchange of 4-hydroxycoumarins, Can. J.Chem., 75, 377- 383 (1997) 16.Cissé L., Tine A., Kaboré L. and A. Saba, Mass spectrometry study of coumarins: Correlation between charges of atoms and fragmentations processes, Spectroscopy Letters, 42,95-99 (2009)17.Cissé L., Kaboré L., Tine A. and A. Saba,Analysis of fragmentation of coumarins in mass spectrometry using the electronic charges of atoms, Bull. Chem Soc. Ethiopia,24(2), 305 (2010) 18.Cissé L., Kabore L., Saba A. and Tine A., Study of mass spectra of 4, 7-disubstituted coumarins: correlation between electronic charges of atoms and fragmentation process, Phys. Chem. News, 53, 101-1072010) 19.Djandé A., Sessouna B., Cissé L., Kaboré L., Tine A and Saba A., AM1 and ESI/MS study of the fragmentation of 4-Acyl Isochroman-1,3-diones: Correlation between Electronic charges of Atoms and Fragmentations processes, Research journalof Chemical Sciences, 1(3),606 (2011)
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20.Djandé A., Sessouma B., Kini F. B. Kaboré L., Guissou I. P; Saba A, AM1 and Electronic Impact Study of the fragmentations of 4-acyl isochroman-1,3-diones, Bull. Chem. Soc. Ethiop., 26(2), 1-8 (2012)  21.Saba A., Thèse Unique, Recherche dans la série des sels de benzopyrylium : Synthèse et étude de la structure des sels de 2-benzopyrylium, UFR-SEA, Université de Ouagadougou1996) 22.Dewar M.J., Zoebish E .G., Healy E.F., Stewart J.P., Development and use of quantum mechanical molecular models. 76. AM1: a new general purpose quantum mechanical molecular model, J. Amer. chem. Soc, 107, 3902 (1985) 
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