Synthesis, Characterization and Biological Screening of Alkylene Dithiophosphate Derivatives of Macrocyclic Complexes of Pb (II)

Alkylenedithiophosphate derivatives of macrocyclic complexes of Pb (II), having N 4 S 4 potential donors, of the general formula, [Pb(L){S 2 P(OR) 2 } 2 ] where L=macrocyclic ligands L 1 , L 2 , L 3 , L 4 and L 5 ; R= C 2 H 5 -, C 3 H 7n or C 3 H 7i have been synthesized from the reaction of [Pb(L)X 2 (where X= Clˉ, NO 3 ˉ or CH 3 COOˉ) with sodium Alkylenedithiophosphate in 1:2 molar ratios in THF. These complexes have been characterized by elemental analysis, molar conductance, molecular weight determinations, IR, 1 H, 13 C NMR. Macrocyclic Complexes of Pb (II) derivatives have been studied by screening them Aspergillus flavus, Fusarium oxysporum, Alternaria alternata and bacteria like Salmonella typhi and Bacillus subtili. Alkylenedithiophosphate derivatives were found to be more fungitoxic and antibacterial than their corresponding macrocyclic complexes.

; R= C 2 H 5 -, C 3 H 7 n or C 3 H 7 i have been synthesized from the reaction of [Pb(L)X 2 (where X= Clˉ, NO 3ˉ or CH 3 COOˉ) with sodium Alkylenedithiophosphate in 1:2 molar ratios in THF. These complexes have been characterized by elemental analysis, molar conductance, molecular weight determinations, IR,

EXPERIMENTAL SECTION
All the lead salts and dicarboxylic acids of A.R. grade were obtained from S. D. fine chemicals, Mumbai and were used without further purification. o-Amino thiophenol was used as obtained from Merck. Solvents were purified and dried by standard methods. The chelating ligand bis-(2-aminophenyl) disulphide was synthesized by the dimerization of the o-amino thiophenol by H 2 O 2 as reported in the literature [33]. Alkylene dithiophosphoric acids were prepared by the reactions of various alcohols like ethanol, normal propanol and iso propanol with phosphorus Penta sulphide. Phosphorus Penta sulphide was added slowly in about 2 hours to the anhydrous alcohol heated on a water bath. After complete addition of phosphorus Penta sulphide, reactants were warmed till the evolution of hydrogen sulphide gas ceased. Solvents were removed under reduced pressure and the Alkylenedithiophosphoric acid thus obtained was purified by distillation under reduced pressure.
Sodium salts of Alkylenedithiophosphoric acids were prepared by the reaction of Alkylenedithiophosphoric acids with corresponding sodium alkoxide in equimolar ratio. To the sodium alkoxide (prepared by dissolution of sodium metal in excess of parent alcohol) was added drop by drop, the benzene solution of Alkylenedithiophosphoric acid in 1:1 molar ratio.
The reaction was exothermic; however, for the sake of completion of reaction the contents were warmed for about 1 hour. Solvent was removed under reduced pressure and the white solid thus obtained was washed with benzene and finally dried under reduced pressure, yielding a white crystalline solid.

Physical Measurements
Microanalyses for carbon, hydrogen, nitrogen and sulphur were determined from SICART, Vallabh Vidyanagar. Lead and phosphorus were estimated by standard method [34]. The molecular weights were determined by Rast Camphor method. Infrared data were recorded on a Perkin-Elmer FT-IR spectrophotometer as KBr pellets. 1 H and 13 C NMR spectra were recorded on a Jeol 270 MHz spectrometer using DMSO-d 6 as a solvent and TMS as an internal standard.

Synthesis of Alkylenedithiophosphate Derivative of Macrocyclic Complexes
Macrocyclic complex mentioned above (1.201 g, 1.3 mmol) was dissolved in THF and was reacted with methanolic solution of ammonium butylene dithiophosphate (0.532g, 2.6 mmol) in 1:2 molar ratio. Reaction mixture was refluxed for 6-8 hours at 200°C. On cooling the yellow crystals of dithiophosphate derivative were separated out, which were filtered through G-3 filtering funnel. This crude product was washed several times with methanol, by vigorous shaking in filtration funnel, to remove the ammonium chloride formed during the reaction. Product was dried under vacuum and was crystallized with THF / C 2 H 5 OH mixture.

Synthesis of alkylenedithiophosphate derivatives of macrocyclic complexes
Macrocyclic complex Tetrathiacyclodiicosane [5,7,16,18] Tetraone (1.201 g, 1.3 mmol) was dissolved in THF and was reacted with methanolic solution of ammonium butylene dithiophosphate (0.532g, 2.6 mmol) in 1:2 molar ratio. Reaction mixture was refluxed for 6 hours at reflux temp on cooling the yellow crystals of dithiophosphate derivative were separated out, which were filtered through G-3 filtering funnel. This crude product was washed several times with methanol, by vigorous shaking in filtration funnel, to remove the ammonium chloride formed during the reaction. Product was dried under vacuum and was crystallized with THF / C 2 H 5 OH mixture.

Synthesis of Alkylenedithiophosphate Derivatives of Macrocyclic Complexes
To an aqueous solution (10 cm 3 ) of Macrocyclic complex Tetrathiacyclodiicosane [5,7,16,18] Tetraone (1.201 g,1.3 mmol) (0.237 g, 1 mmol was dissolved in THF and was reacted with methanolic solution of ammonium butylene dithiophosphate (0.532g, 2.6 mmol) in 1:2 molar ratio. To this hot solution, an aqueous solution (10 cm 3 ) of an amino acid (HL) was (1 mmol) with constant stirring. The reaction mixture was kept in the microwave for about 10-13 min. The complexes were obtained by raising the pH of the reaction mixture by adding a diluted NaHCO 3 solution.The solid complex obtained was filtered and washed with Water-ethanol. A comparison of these two methods is given in Table 2.

RESULTS AND DISCUSSION
The reaction mixture was refluxed for 3 h. on cooling the crystals of the dithiophosphate derivatives separated out. Except THF and DMSO, these derivatives are insoluble in almost all organic solvents. The molar conductance of 10-3 M solution in DMSO lie in the range 03-06 ohm-1cm2mol-1, showing that these complexes are non-electrolyte. The molecular weight determinations indicate their monomeric nature (Table-3).

Antimicrobial Activity
Like their precursor macrocyclic complexes, the antifungal activity of alkylene dithiophosphate derivatives has been tested against three fungi, Aspergillus flavus, Fusarium oxysporum and Alternaria alternata The screening data for the average percentage inhibition of the fungi at 100, 125 and 200 ppm concentration are given in Table-4. The values obtained suggest that the alkylene dithiophosphate derivatives of macrocyclic complexes are more fungitoxic than their precursor macrocyclic complexes as well as the alkylene dithiophosphoric acids. Further the data also indicate that with the increase in the concentration, the fungitoxicity also increases.
The antibacterial activity against two bacteria, namely S.typhi and B.subtili, were tested by the inhibition zone technique [46]. The data obtained are presented in Table-5. The values suggest that the alkylene dithiophosphate derivatives of macrocyclic complexes are more antibacterial than their precursor macrocyclic complexes (PbL 1 -PbL 5 ).

Magnetic Studies
Magnetic moments of the metal complexes calculated from the measured magnetic susceptibilities after employing diamagnetic corrections. The observed μ eff values presented in Table 3. Suggest the octahedral geometry for nickel complexes. Study also shows paramagnetic nature of synthesized complexes.

Infrared Spectral Data
In the macrocyclic complexes, the four bands in the region 1680-1638(s), 1582-1516(m), 1272-1240(s) and 690-648(w) cm -1 have been ascribed to the amide I, amide II, amide III and amide IV in-plane deformation vibrations, respectively [47]. A broad band in the region 3189-3104 cm -1 has been assigned to the (N-H) vibration of the secondary amino group. These bands do not show any significant change from  their parent macrocyclic complexes. Two bands present in the region 1072-1040 cm -1 and 888-840 cm -1 may be assigned to (P)-O-C and P-O-(C) stretching vibrations, respectively [48].The band present between 999-954 cm -1 may be attributed to the ring vibrations of dioxaphospholanes and dioxaphosphorinanes respectively, which are probably coupled with C-C stretching vibrations [49,50]. A weak band present in the region 570-538 cm -1 has been attributed to P-S symmetric and asymmetric vibrations. A strong band observed in the region 728-680 cm -1 , which also appears in ammonium alkylene dithiophosphate at around the same region, is attributed to the P=S moiety. This indicates the unidentate behavior of the dithiophosphate moieties [51,52]. The presence of sharp and weak bands in the region 483-418 cm -1 and 364-320cm -1 have been assigned to (Pb-N) and (Pb-S) vibrations, respectively [7,8,53].

1 H NMR Spectral Data
The structure of alkylene dithiophosphate derivatives of macrocyclic complexes of Pb(II) have been further confirmed by recording the 1 H NMR using DMSO-d 6 as a solvent and TMS as an internal standard. In addition to the protons appear in the parent macrocyclic complexes, the additional protons of alkylene dithiophosphate moieties appear in the spectra. The methyl protons of tetramethyl ethylene moiety, butylene dithiophosphate moiety and neo-pentylene dithiophosphate moiety appeared in the range  1.36 to 1.59 ppm. The protons of methylene and methine moieties appear in the range  3.8 to 4.9 ppm. The broad singlet observed between  8.09 to 8.36 ppm has been assigned the proton of-C(O)NH-group. The protons of -CH 2 -group of malonic acid appear as a singlet in the range,

13 C NMR Spectral Data
Alkylene dithiophosphate moieties spectral data shows The carbons of -CH 3group of tetramethylene, butylene and neopentylene dithiophosphate moieties appear in the range  12.14 to 14.

CONCLUSION
The object of invention Mixed Ligand Macrocyclic Complexes of Pb (II) shows the antimicrobial activity. A process for preparation of Mixed Ligand Macrocyclic Complexes of Pb (II) under the microwave method very fast with high yield compare to the thermal process. Magnetic studies indicate the paramagnetic nature of the complexes. lead ion square-planar geometry and each alkylene Di thiophosphate moiety occupies the axial positions binding the central lead ion in a unidentate manner. The IR spectra show the bonding of the metal ion through -N and -X donor atoms of the two ligands. The biological study shows that complexes are less active against Aspergilus flavus, Fusrium oxisporum, Alternaria alternata than compared with the standard antibacterial compound Bavistin, the complexes show modest activity. The antibacterial activity of the Pb(II) complexes shows that Pb(II) complexes were less active than the free ligand against Bacillus subtili and Salmonella typhi.

CONSENT
It is not applicable.

ETHICAL APPROVAL
We conducted our research after obtaining proper IEC approval.