Spectral and Biological Studies on Microwave Assisted Synthesized Zn(II) Complex of Schiff Base Derived from Sulphonamides

A big challenge, academic world and industry is facing the relationship of modern societies to the environment that requires reinventing the manufacture and use of materials. Synthetic methodologies now a day should be designed to use and generate substances that possess little or no toxicity to human health and the environment The miceowave assisted synthesis and characterization of Zn (II) complexes of Schiff bases derived from three diuretic drugs acetazolamide, furosemide and hydrochlorothiazide are reported here. The ligand and complexes have been suitably synthesized and isolated in crystalline form. Molar conductance values suggest the non-electrolytic nature of the complexes.On the basis of elemental analyses, electrical conductivity data and molecular weight data the adducts are assigned to the general composition [M(L)2].All the adducts are diamagnetic in nature. The IR studies indicate that ligand is coordinated to metal through azomethine nitrogen atom. The diuretic activity of the ligand FSM-SA and complex FSM-SA-Zn was assessed in vivo following the protocol of Institutional Animal Ethical Committee norms. While studying the results of the experiment it was concluded the diuretic activity of the FSM-SA and FSM-SA-Zn was found to be more than the parent drug. Partical size studies further suggest that the size of metal complexes is smaller than the drug molecule. Keywords-Complexes, Schiff base, diuretic, acetazolamide, furosemide and Hydrochlorothiazide.


IntroDuCtIon
Green chemistry is an invention, design ,development and application of chemical product and processes to reduce or eliminate the use and generation of the substances hazardous to the human health and environment.Microwave assisted organic synthesis is one such component of green chemistry 1 .
Schiff bases and their metal complexes have been found to posses important biological and industrial applications.There is enormous interest presently in the field of coordination chemistry of '3d'transition metal ion with Schiff bases [2][3][4][5][6][7][8] .Metal ions play a vital role in the biological activity and certain metal complexes of the drug have been found to be more potent than their parent drug 9 .Survey of literature reveals that very few studies have been done on metal complexes of Schiff bases of diuretic drugs.We report herein the synthesis and characterization of some bipositive 3d metal ion chelates of diuretic drugs along with the assessment of diuretic activity.In continuation of our previous work on metal complexes of established drugs [10][11][12] the synthesis and structural studies of (AZM-SA) 2 Zn, (FSM-SA) 2 Zn, (HCT-SA) 2 Zn complexes are described below.Conductivity measurments were carried out on Systronics digital direct reading conductivity meter using conductivity cell having cell constant 1.0.The IR spectra of ligand and complexes were recorded in KBr pallets on Perkin Elmer spectrophotometer in the range 4000-400 cm -1 .Magnetic susceptibility measurements were done on Vibrating Sample Magnetometer at room temperature.The 1HNMR spectra of ligand and complexes were run in dMSO d6 on a Joel-FX-100 Spectrophotometer using TMS as an internal standard.diuretic activity of FSM-SA and (FSM-SA) 2 Cu complex was assessed at Jawahar General microwave procedure for the synthesis of Schiff bases (AK1-AK5).Synthesis of ligand (Drug-Schiff base)General microwave procedure for the synthesis of Schiff bases Equimolar solutions of pure drugs (0.01M) and salicyldehyde (0.01M) were taken in aqueous methanol mixture (1:1 ratio).Both the solutions were mixed contents were subjected to microwave irradiation at an interval of 1 min at 400 W for about 8-10 min;The reaction mixture was kept overnight.Crystals of drug-Schiff base (AZM-SA,FSM-SA,HCT-SA) were formed in the reaction mixture, which were washed with 50:50 methanol : water mixture, filtered, dried and weighed.Melting point was recorded

ligand-Metal ratio and Stoichiometry
To confir m the ligand metal ratio, conductometric titrations using monovariation method were carried out on Systronics conductivity meter0.01Msolution of drug-Schiff base was   Analytical data of these complexes are in agreement with the composition.
Lowering of azomethine frequencies in the metal complexes indicate its involvement in coordination 29 .The disappearance of frequencies of phenolic -OH in complexes supports its involvement in complexation.The spectra of ligand(FSM-SA) and its metal complexes were recorded in dMSO.

FSM-SA
The (N=CH) group proton shows triplet peak at d (8.59-8.63)ppm, which can be assigned to azomethine(HC=N) proton. 30In the ligand (FSM-SA) peaks observed at d( 8.34-8.40)ppm, d(7.06) ppm and ä( 6.36-6.43)ppmare assigned to aromatic protons due to the different environments around the protons. 31The ligand showed the single peak at   (FSM-SA) 2 Zn complex In The 1 HNMR spectra of (FSM-SA) 2 Zn singlet peak observed at d (9.162) is corresponds to -NH proton in .Singlet peak observed at d (8.44) ppm is corresponds to azomethine (NC=H) proton.In spectrum singlet peak observed at ä (7.571) ppm are corresponds to proton of benzene ring having -COOH substitution at para position.The spectra showed peaks at d(6.936)ppm, d (6.33-6.77)ppmand d (7.244)ppm due to aromatic proton (loc.cit.).In The 1 HNMR spectra of (FSM-SA) 2 Zn singlet peak observed at d (3.512) ppm is assignable to TMS.The (N=CH) group Proton shows the downfield shifting which supports the coordination of metal to (N=CH) group through nitrogen, which is also supported by IR spectral data.Absence of signal due to phenolic -OH suggests the coordination of phenolic oxygen to the metal.This has also been supported by IR spectral data.The spectra do not show any peak due to coordinated water molecule which indicates square planer geometry of the complexes.
The 1 HNMR spectra of HCT-SA and its (HCT-SA) 2 Zn complex The spectra of ligand(HCT-SA) and its metal complexes were recorded in dMSO.
HCT-SA -The (N=CH) group proton shows a triplet at d (7.91-7.99)ppm, which corresponds to -NH proton.The peaks observed at d (7.48) ppm may be attributable to azomethine proton.Spectra of ligand(HCT-SA) showed peak at d( 6.97)ppm which can be assigned to aromatic protons due to the different environments around the protons 32 .Signal observed at d (4.70-4.73)ppm has been assigned to phenolic -OH proton.Peaks observed at d (3.33) ppm can be attributed to TMS (Tetra Methyl Silane).

(hCt-SA) 2 Zn
The signal observed at d (7.959-8.003)ppm in 1 HNMR spectra of (HCT-SA) 2 Zn has been assigned to azomethine (NC=H) proton 34 .The peaks observed at d (7.49) ppm in the spectra of (HCT-SA) 2 Zn are attributable to -NH proton 33 .The 1 HNMR spectra of (HCT-SA) 2 Zn showed peaks at ä(6.94)ppm due to aromatic proton (loc.cit.) .Peaks observed at d (3.33)   ppm may be assigned to TMS.The (N=CH) group Proton shows the downfield shifting which supports the coordination of metal to (N=CH) group through nitrogen 34 , which is also supported by IR spectral data.In spectra absence of signal due to phenolic OH suggests the coordination of phenolic oxygen to the metal.This has also been supported by IR spectral data.The spectra do not show any peak of coordinated water molecule, which indicates square planer geometry of the complexes.

Diuretic Activity
The average volume of urine output for various sets of experiments is shown in tabulated form-The average volume of urine output for various sets of experiments explains clearly the order of diuretic activities of the drug its Schiff base and metal complexes as follows-(FSM-SA) 2 Zn(Complex)>FSM-SA(Schiff base) > FSM(Pure drug)>Water The order is indicating that a metal complex of the drug is more potent diuretic than its Schiff base and pure drug itself.The average volume of urine output for various sets of experiments explains clearly the order of diuretic activities of the drug its Schiff base and metal complexes as follows-(FSM-SA) 2 Zn(Complex)>FSM-SA(Schiff base)> FSM(Pure drug)>Water The order is indicating that a metal complex of the drug is more potent diuretic than its Schiff base and pure drug itself.

Fig. 9 d
Fig. 9 Pure sample of acetazolamidemide (AZM) molecular formula C 4 H 6 N 4 O 3 S 2 ,, molecular weight 222.24, was obtained from Shalaks Pharmaceuticals Pvt. Ltd New delhi.Pure sample of furosemide (FSM) molecular formula C 12 H 11 N 2 O 5 S, molecular weight 330.75, was obtained from Geno PharmaceuticalsPvt.Ltd., Goa.Pure sample of Hydrochlorothiazide (HCT) molecular formula C 7 H 8 Cl N 3 O 4 S 2 , molecular weight 297.74, was obtained from Novartis India Pvt.Ltd, Mumbai.These drugs were used as such for the synthesis of ligand.Metal salts were Qualigen chemicals.Solvents used were methyl alcohol and acetone.All the chemicals used were of analytical grade. .Elementa analysis (CHN) were carried out on a Carlo Ebra 1106 Thomas and Coleman analyzer.

table 4 : (observations for group I) Average volume of urine excreted by control animals (Mice were fed with 0.5ml acidified double distilled water)
acetone : water mixtures and refluxed for four hours with 0.05M solution of ZnCl 2 .. Fine crystalline compounds appeared in the solutions.Complexes were washed with acetone, filtered, dried and weighed.Melting points were recorded.

activity of FSM-SA and (FSM-SA) 2 Zn complex
[21][22] activity of FSM-SA and (FSM-SA) 2 Cu complex was assessed at Jawahar Lal Nehru Cancer Hospital and Research Center, Bhopal, following the protocol and Institutional Animal Ethical Committee norms.The experiment was carried out on mice.detailedsurvey of literature indicated that dose prescribed for human being is also safe in mice The color, melting point, yield percentage, stability constant, free energy change and molar conductance value are summarized in table I & analytical data are summarized in table II.Conductometric studies, monovariation method and Job's method of continuous variation modified by Turner and Anderson[21][22]indicate the formation of 2:1 (L: M) complexes of Schiff base of ligands with Zn ion. .