SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL ACTIVITY OF SOME NEW ORGANIC TELLURIIUM COMPOUNDS CONTAINING THIADIAZOLES

tellurium tribromide (2) was by the of (1) with tellurium in in Later compound (2) with solution of sodium sodium The 1 H NMR spectra of all compound 1-5 showa signal at 2.02 , 1.27 , 1.35, 1,07and 1.31 ppm respectively due to SH(1). The signals appeared at 7.8 , 7.1, 7.0, 7.0 and 6.89 ppm can be attributed to CH (6) respectively . The signals at 7.8, 7.9, 7.967.97 and 7.17ppm also can be attributed to CH (7) respectively[26] , The signals at 8.3, 8.5,8.5 and 7.95 may due to NH(3). While chemical shifts for NH(4) appeared at 8.8, 8.9, 8.9, 8.89 and 8.78ppm .the chemical shift for NH(5) group appeared at 11.3, 11.8,11.8,11.89 and 11.8 ppm respectively. The 1 H NMR spectra of compound 3 ,which containing pyrrolidinedithio- carbamato molecules show two types of signals may refer to protons related to three pyrrolidine rings at 1.99ppm for CH(7,10,7 - ,10 - ,7 = ,10 = ) and 2.27ppm for CH(8,9,8 - ,9 - ,8 = ,9 = ). The 1 H NMR spectra of compound 4 ,which containing piperidindithiocarbamato molecules show two signals to protons related to threepiperidine ring at 1.42ppm for CH(7,10,7 - ,10 - ,7 = ,10 = ) and 3.02ppm for CH(8,9,8 - ,9 - ,8 = ,9 = ). The 1 H NMR spectra of compound 4 ,which containing piperidinedithiocarbamato molecules show two signals to protons related to threepiperidine ring at 1.99ppm for CH(7,10,7 - ,10 - ,7 = ,10 = ) and 4.10ppm for CH(8,9,8 - ,9 - ,8 =


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The IR spectra for compounds (2-5) show week bands in the range (420-459)cm -1 which due to ʋ(Te-C) vibration [21]. All IR spectra showed a week to medium bands in the range (3286-3586)cm -1 attributed to ʋ (N-H) [22]. IR spectra for compounds (1-5) show a week to medium bands in the range (3097-3101) cm -1 may attributed to ʋ(C-H) aromatic vibrational frequencies while the ʋ(C-H) aliphatic appeared at the range(2854-2962)cm -1 in compounds [23]. The IR spectra for compounds (1-5) showed a week ,medium or strong bands in the range (1608-1616)cm -11 may attributed to ʋ(C=N) [24]. All compounds show the strong bands at 1500-1515 cm -1 and 1330 -1365 cm -1 can be attributed to the asymmetrical and symmetrical stretching vibrations of the NO 2 group, The IR spectra for dithiocarbamate derivatives compounds (3-5) Distinguished with the appearance of a strong band in the region (972-1026) cm -1 due to the asymmetric vibration of C=S bond [25].
The spectral region 200-800 nm was investigated by UV-Vis spectrophotometry at a concentration of 1.0 x 10 -4 M for all compounds in ethanol solution. In general, the UV-visible spectra for compounds 1-5 show ᴫ-ᴫ * transitions due to the thiodiazole and aromatic rings and n-ᴫ * transitioncan be considered as an evidence to coordinate thiodaziol with tellurium atom or tellurium atom with dithiocarbamate derivatives compounds [23,26].
The 13 C NMR spectrum for compounds 3, 4 and 5, show signals at 127,115 and 135 ppm respectively due to C 10 atoms (Te-C). The 13 C NMR spectrum for compound 3appeared signal at 23ppm can be attributed to the C 17 atom .the signal at 26 ppm corresponding to the C 16 and C 18 atoms ,while signal at 39 due to the C 15 and C 18 atoms . The signals at 55, 95, 149, 166,170, 174 and 178 ppm can be attributed to the C 2 , C 5 , C 13 , C 11 ,C 12 , C 14 and C 9 atoms respectively.The 13 C NMR spectrum for compound 4appeared signal at 23ppm can be attributed to the C 17 atom .the signal at 26 ppm corresponding to the C 16 and C 18 atoms ,while signal at 39 due to the C 15 and C 19 atoms. The signals at 55, 110, 141, 156, 169 and 176 ppm can be attributed to the C 2 , C 5 , C 13 , C 12 , C 14 and C 9 atoms respectively. The 13 C NMR spectrum for compound 5appeared signal at 13ppm can be attributed to the C 15 and C 18 atoms .the signal at 39 ppm corresponding to the C 2 atom ,while signal at 64 due to the C 16 and C 17 atoms. The signals at 66, 141, 142, 167, 177 and 178 ppm can be attributed to the C 5 , C 13 , C 12 ,C 11 C 14 and C 9 atoms respectively.

Biological activity:
The antibacterial activity of organotellurium compound show in table (1) . It can be concluded that all the compounds have displayed biological activity against the studied bacteria. In general, Compound2was found to be equal to inhibition activity against both bacteria (Staphylococcus aureusand Escherichia coli) inhibition zone (IZ)40 mm with amoxicillin. Compound 3 showed a good activityagainst both bacteria with an IZ 30mm comparable to amoxicillin .A good activityagainst Escherichia coli with an(IZ) 30mm in compound 4appeared a little activity against Staphylococcus aureus bacteria with an (IZ) 20 nm comparable to amoxicillin. The results showed that the compound 5 has against Escherichia coli with an (IZ) 45 mm more potent than positive controls(IZ) 40 mm, while appeared a little activity against Staphylococcus aureus bacteria with an (IZ) 20 nm comparable to amoxicillin. Generally, the antimicrobial activity oftelluratedthiadiazole compoundscan be attributed to the reasons:1,3,4-Thiadiazole derivatives can produce mesoionic salts as shown in Figure 1. Mesoionic system contains a five-membered heterocyclic ring which possesses a sextet of p and π electrons and positive charge counterbalanced by formal negative charge. Despite their internal charges, the mesoionic structures of 1,3,4thiadiazoles behave as neutral compounds and able to cross cellular membranes, and this contributes to the good cell permeability. The mesoionic nature of 1,3,4-thiadiazoles enables these compounds to interact strongly with 659 biomolecules (eg, DNA and proteins) [28,29]. The mode of action of the dithiocarbamate derivatives may be involve the formation of a hydrogen bond through the -N ….. C(S)Shgroup with the active centres of the bacteria cell constituents resulting in the interference with the normal cell process [30].

Conclusion:-
A new series of telluratedthiadiazole compounds were prepared characterized and biologically evaluated as antimicrobial agents. The synthesized compounds antibacterial activity against Staphylococcus aureus and Escherichia coli. Compounds 2and 3 showed a good antibacterial activity against S. aureus and E. coli against then other organo tellurium compounds.