Structure investigation of sertraline drug and its iodine product using mass spectrometry, thermal analyses and MO-calculations

Sertraline (C(17)H(17)Cl(2)N) as an antidepressant drug was investigated using thermal analysis (TA) measurements (TG/DTG and DTA) in comparison with electron impact (EI) mass spectral (MS) fragmentation at 70eV. Semi-empirical MO-calculations, using PM3 procedure, has been carried out on neutral molecule and positively charged species. These calculations included bond length, bond order, bond strain, partial charge distribution and heats of formation (DeltaH(f)). Also, in the present work sertraline-iodine product was prepared and its structure was investigated using elemental analyses, IR, (1)H NMR, (13)C NMR, MS and TA. It was also subjected to molecular orbital calculations (MOC) in order to confirm its fragmentation behavior by both MS and TA in comparison with the sertraline parent drug. In MS of sertraline the initial rupture occurred was CH(3)NH(2)(+) fragment ion via H-rearrangement while in sertraline-iodine product the initial rupture was due to the loss of I(+) and/or HI(+) fragment ions followed by CH(2)NH(+) fragment ion loss. In thermal analyses (TA) the initial rupture in sertraline is due to the loss of C(6)H(3)Cl(2) followed by the loss of CH(3)-NH forming tetraline molecule which thermally decomposed to give C(4)H(8), C(6)H(6) or the loss of H(2) forming naphthalene molecule which thermally sublimated. In sertraline-iodine product as a daughter the initial thermal rupture is due to successive loss of HI and CH(3)NH followed by the loss of C(6)H(5)HI and HCl. Sertraline biological activity increases with the introduction of iodine into its skeleton. The activities of the drug and its daughter are mainly depend upon their fragmentation to give their metabolites in vivo systems, which are very similar to the identified fragments in both MS and TA. The importance of the present work is also due to the decision of the possible mechanism of fragmentation of the drug and its daughter and its confirmation by MOC.

Structure investigation of codeine drug using mass spectrometry, thermal analyses and semi-emperical molecular orbital (MO) calculations

Codeine is an analgesic with uses similar to morphine, but it has a mild sedative effect. It is preferable used as phosphate form and it is often administrated by mouth with aspirin or paracetamol. Therefore, it is important to investigate its structure to know the active groups and weak bonds responsible for its medical activity. Consequently in the present work, codeine was investigated by mass spectrometry and thermal analyses (TG, DTG and DTA) and confirming by semi-empirical MO-calculation (PM3 method) in the neutral and positively charged forms of the drug. Some results of studying the d-block element complexes of codeine were used to declare the relationship between drug structure and its chemical reactivity in vitro system. The mass spectra and thermal analyses fragmentation pathways were proposed and compared to each other to select the most suitable scheme representing the correct fragmentation of this drug. From EI mass spectra, the main primary cleavage site of the charged drug molecule is that due to beta-cleavage to nitrogen atom in its skeleton. It occurs in two parallel mechanisms with the same possibility, i.e. no difference in appearance activation energy between them. In the neutral drug form the primary site cleavage is that occurs in the ether ring. Thermal analyses of the neutral form of the drug revealed the high response of the drug to the temperature variation with very fast rate. It decomposed in several sequential steps in the temperature range 200-600 degrees C. The initial thermal fragments are very similar to that obtained by mass spectrometric fragmentation. Therefore, comparison between mass and thermal helps in selection of the proper pathway representing the fragmentation of this drug. This comparison successfully confirmed by MOC. These calculations give the bond order, charge distribution, heat of formation and possible hybridization of some atoms in different position of the drug skeleton. This helps the successful choice of the weakest bond at which both mass and thermal fragmentation occurs. Therefore, the best fragmentation pathway of this drug is correctly selected. The effect of such fragmentation on the drug behavior in the human body can be expected as a result of comparing these data with that obtained on studying codeine metal complexes using mass and thermal fragmentation techniques.

Investigation of diazepam drug using thermal analyses, mass spectrometry and semi-empirical MO calculation

In the present work diazepam (Dz) drug was investigated using thermal analyses (TA) measurements (TG/DTG) in comparison with EI mass spectral (MS) fragmentation at 70 and 20 eV. Semi-empirical MO calculations, MNDO procedure, have been carried out on diazepam both as neutral molecule and the corresponding positively charged molecular ion. These include molecular geometry, bond order, charge distribution, heats of formation and ionization energy. Thermogravimetric and kinetic analysis, reveal a high response of the drug to the temperature variation with very fast rate. It is completely decomposed in the temperature range between 204 and 340 degrees C with average kinetic energy (KE) at 164.69 kJ mol(-1). On the other hand, diazepam can easily fragmented at low energy after ionization by electron energy at 9.56 eV. The losses of CO gas molecules followed by chlorine gas from the entity of diazepam (both neutral and charged molecular ion) as the best selected pathway were observed in both mass spectra (MS) and thermal analyses (TA). MNDO calculation was applied to declare both TA and MS observations.