My progress on February and the abstract

            This month was really good for our investigation because we finally got the results of the elemental analysis of my compounds with benzothiazoles ligands and they show a difference of less than 0.5 % with the theoretical values demonstrating the purity of the complexes.  Now that we are completely sure that the syntheses are done we are going to proceed to know their activity in cancer cells line. Our major problem is the time. To do this stuff we need a lot of time that sometimes is very difficult to have because of our classes. The second problem is that the quantity of the samples is not enough to make several analyses and we may do them once more passing through the process of characterization again. To reduce these problems we are working in group and helping each other to have things on time and using the minimum of sample necessary for the tests we will be working on.  In the scale of progress I believe that my research is right now in a 3, because a five will be show their reactivity comparing with cisplatin.

Abstract:

 Platinum complexes have been a subject for the development of drugs to treat certain kinds of cancer. Cisplatin, cis-[PtCl₂(NH₃)₂] is successfully used in chemotherapy, and the new drug picoplatin, cis-[PtCl₂(NH₃)(2-methylpyridine)] has shown evidence of antitumor activity in cisplatin-resistant cells. The purpose of this experiment is to develop new compounds structurally related to picoplatin, using the mixed-amine system: NH₃/benzothiazole.  The change in the amine 2-methylpiridine and the addition of methyl groups to the benzothiazole ligand can have significant effects in the activity or toxicity of Pt compounds. The present experiment deals with the synthesis and characterization of mixed-amine compounds cis-[PtCl₂(NH₃)(L)], where L=1,3-benzothiazole, 2-methylbenzothiazole and 2,5,6-trimethylbenzothiazole.  The complexes were prepared by the direct reaction of an aqueous solution of K[PtCl₃(NH₃)] with an ethanol solution of the ligand.  The complexes cis-[PtCl₂(NH₃)(benzothiazole)] (1), cis-[PtCl₂(NH₃)(2-methylbenzothiazole)] (2) and cis-[PtCl₂(NH₃)(2,5,6-trimethylbenzothiazole)] (3) were characterized by ¹H nuclear magnetic resonance (500 MHz, in DMF-d₇) and infrared spectroscopy.  The infrared bands characteristics of the amine group, the methyl groups (in complexes 2 and 3) and the benzothiazole ligand are present in the spectra and will be presented. The ¹H NMR spectrum of 1 shows the aromatic protons of coordinated benzothiazole: a singlet at 9.975 ppm, assigned to H(2), doublets at 8.3 ppm and 9.0 ppm, assigned to H(4) and H(7); and triplets at 7.78 ppm and 7.657 ppm, corresponding to H(5) and H(6). The broad signal at 4.47 ppm corresponds to the ammine group. The spectrum of the complex with 2-methylbenzothiazole (2) was also recorded. The doublets at δ=8.17 ppm and δ=9.12 ppm are assigned to H(4) and H(7), the triplets at 7.61 ppm and 7.73 ppm correspond to H(5) and H(6). The resonance at 3.36ppm is due to the protons of the methyl group in the second position of the molecule.  The broad signal at 4.39 ppm is the signal of the NH₃. The ¹H NMR spectrum of the complex with 2,5,6-trimethylbenzothiazole (3) also shows the aromatic protons: the doublets at δ=8.88 ppm and δ=7.87ppm are due to H(4) and H(7), the peaks at 2.42 ppm, 2.49ppm and 3.31ppm correspond to the protons of the methyl groups attach to the sixth, fifth and second carbon atoms of the benzothiazole moiety. The broad signal positioned at 4.38 ppm is the signal of NH₃. The presence of the characteristic NH₃ band in all spectra confirms the mixed ligand nature of the new compounds.   The spectral studies confirm that the synthesis was successful, and the products mainly consist of the desired cis-[PtCl₂(NH₃)(2-methylbenzothiazole)], cis-[PtCl₂(NH₃)(2,5,6-trimethylbenzothiazole) and cis-[PtCl₂(NH₃)(benzothiazole)] complexes.