Reactions of MoCl5 with Succinimide, Imidazole, 3-Methylpyridine and 4-Methylpyridine in THF

Introduction

Succinimide

Succinimides¹ are used as precursors for biological applications. Succinimide is a part of various biologically active molecules having properties: antitumour², CNS depressant³, anorectic⁴, hypotensive⁵, analgesic⁶, cytostatic⁷, nerve conduction blocking⁸, antispasmodic⁹, bacteriostatic¹⁰, muscle relaxant¹¹, antibacterial¹², antifungal¹³, anti-convulsant¹⁴ and anti-tubercular¹⁵.

Imidazole

Imidazole containing drugs are used^16-28 as:anticoagulants, 20-carboxypeptidaseinhibitors,antifungal, β-lactamase inhibitors,hemeoxygenase inhibitors, anticancer, antitubercular, anti-inflammatory,antibacterial, antiviral, antidiabetic HETE (20-Hydroxy-5,8,11,14-eicosatetraenoic acid) synthase inhibitors, antimalarial and antiaging agents.

3-Methylpyridine

3-Methylpyridine²⁹ is used to prepare agrochemical chlorpyrifos³⁰. As compared to 2-methylpyridine/4-methylpyridine^{31, 32} there is low degradation andpoor volatility of 3-methylpyridine from water samples.3-Methylpyridine is used as an antidote for organophosphate poisoning ³³. It is biodegradable.

4-Methylpyridine

Many heterocyclic compounds can be prepared from 4-methylpyridine³⁴. It is a precursor to other commercially significant species, often of medicinal interest. 4-Methylpyridine is a precursor for the preparation of the antituberculosis drug³⁵ ‘isoniazid’. It is very reliable and commonly used medicine for tuberculosis.

It has been noted that many drugs havegreater activity as metal chelates as compared to organic compounds^36-41.

Aim of Investigation

Molybdenum(V) chloride has been reported to react with a variety of N-heterocyclic bases.Many reactions of aromatic azoles, diaminoalkanes, imides, 4-phenylimidazole-2-thiol, alkylpyridines, 2-thiazoline-2-thiol, mercaptopyridine-N-oxide sodiumand thiols with MoCl₅ have been studied^42-47 by the author.

In view of the fact that complexes of these bases with transition metalsshow various applications. Complexes of succinimide, imidazole, 3-methylpyridine and 4-methylpyridine with MoCl₅ have been synthesized and studied.Characterization of these complexes was executed with ¹H NMR, ¹³ C NMR, FTIR, LC-MS, microbiological studies and elemental analysis.

Materials and Methods

Succinimide, imidazole, 3-methylpyridine, 4-methylpyridine and MoCl₅were bought fromSigma-Aldrich.

The products are easily oxidized/hydrolysed by air/moisture, so all procedures and work outs were handled in vacuum line using dry nitrogen atmosphere to protect the products from oxidation/hydrolysis by air/moisture.

Ligand dissolvedin dry THF was combined from dropping funnel withMoCl₅dropwise with continuous agitation. The reaction was carried outfor 7-8 h.Filtration unit fitted with G-4 sintered glass crucible was used for filtration and isolation of products.

Molybdenum analysis was performed by oxinate method gravimetrically⁴⁸. Chlorine analysis was performed by silver chloride method gravimetrically⁴⁸.Thermo Finnigan Elemental Analyser was used for analysis of remaining elements. Perkin-Elmer 400 FTIR Spectrometer was used for obtaining vibrational spectra.¹H/¹³C nuclear magnetic resonancespectrain DMSO-d₆ were obtainedwithMultinuclear BruckerAvance-II 400 NMR spectrometer. LC-MS spectra were obtainedin the range 0 – 1100 m/z. Above instruments were used atP. U. Chandigarh.

Antibacterial and antifungal activities of molybdenum compounds synthesized were tested using strains: gram positive bacteria Staphylococcus aureus (MTCC-737), gram negative bacteria E. coli (MTCC-1687), fungi Candida albicans (MTCC-227) and Aspergillusniger (MTCC-282). Agar well diffusion assay method was used.Standard drug (amoxicillin) for bacteria and standard drug (ketoconazole) for virus as reference were used.MTCC (The Microbial Type Culture Collection and Gene Bank, Chandigarh, India) cultures were used. Testing was carried out at ISF Analytical Laboratory (ISF College of Pharmacy), Ferozepur Road, Moga, Punjab, India.

Reactions

(R)/(F) represent the product source,

Results and Discussions

Elemental Analysis

Table 1: reveals the percentage of the observed (theoretical) values of the elements.

(Elemental Analysis)
Compounds	Cl	Mo	H	C	N
MoO2Cl4(C4H5NO2)4(C4H8O), [1] (Black/738.0)	18.77 (19.24)	12.10 (13.00)	02.57 (03.25)	32.37 (32.52)	06.85 (07.58)
Mo2O12Cl7(C3H4N2)7, [2] (Yellowish green/1108.5)	21.78 (22.41)	16.93 (17.32)	02.81 (02.52)	22.28 (22.73)	17.01 (17.68)
Mo3Cl8(C6H7N)4(C4H8O)2, [3] (Brown/1088.0)	25.57 (26.10)	25.53 (26.47)	03.88 (04.04)	36.07 (35.29)	04.68 (05.14)
Mo3Cl8(C6H7N)4(C4H8O)2, [4] (Dark green/1088.0)	25.33 (26.10)	25.97 (26.47)	03.49 (04.04)	34.67 (35.29)	04.53 (05.14)

FTIR Spectra

Succinimide^{49, 50} has N-H stretching at 3411 cm^-1 & 3222 cm^-1. Band at 3434 cm^-1 suggests presence of N-H group in [1]. Stretching at 938 cm^-1 and 918 cm^-1 reveal the existence of cis-MoO₂²⁺ core^{51, 52} in [1]. C=O frequency has not altered much from 1773 cm^-1 and 1711 cm^-1, indicating there by absence of Mo–O coordination in [1]. There seems to be little decrease in C=O bond order (Table-2).

Table 2:  FTIR absorptions in cm⁻¹

Table 2: (FTIR absorptions in cm−1)
Assignments	Succinimide49, 50	[1]
N-H str.	3411 s, b, 3222 s, b	3434.0 s, b
CH2 sym. str.	2962, 2946 w
C=O sym., H-N-C in plane bending	1773 m	1773.5 sh
C=O asym., H-N-C in plane bending	1711 vs, b	1706.1 s
CH2 sym. scissoring	1432 m	1425.9 sh
CH2asym. scissoring	1402 m
C-N-C asym. str., H-N-C in plane bending	1348 s, 1335	1371.8 m
CH2 bending, ring in plane bending	1296 s	1298.1 m
CH2 bending	1242	1247.3 sh
C-N-C asym. str., H-N-C in plane bending	1188 s,	1190.3 s
C-C str., CNC sym. str.	850	853.5 sh
CH2 bending, ring out of plane bending	818 s	818.0 w
OCN asym. out of plane bending	631 m	643.3 m
OCN sym. out of plane bending, CH2 bending	541 w	556.3 sh
Mo-N str.		416.7 w
Mo=O Str. of cis-MoO22+ core51, 52		938.2 w, 918.1 sh

 

It is reported that N-H stretching of imidazole^{53, 54} appears at 3722 cm^-1-3272 cm^-1. There is presence of broad band at 3431 cm^-1-3000 cm^-1 pertaining to N-H group in [2]. This broadening occurs in the solid state (KBr disk) because of hydrogen bonding. A strong band at 975 cm^-1 is suggestive of terminal Mo=O^{51, 55, 56} in [2] (Table-3).

Table 3: FTIR absorptions in cm⁻¹

Table 3:  (FTIR absorptions in cm−1)
Assignments	Imidazole53, 54	[2]
N-H  str.	3722 vb, 3657 vb, 3272, 3242, 3238	3431.1vs, 3000 s, vvb
C-H str.	3195, 3166	3157.8sh, 2997.0sh
C=C ring str.	1560, 1502	1633.2 s, 1592.5sh
N-C  ring str.	1435	1445.4 w
C-H in plane bending	1094, 1073	1194.1 w, 1079.9 w
C-H out of plane bending (wagging), Ring twisting	817, 728	760.7 m
Ring twisting	648	627.3 m
Ring twisting, N-H wagging	527
Terminal Mo=O51, 55, 56str.		975.2 m

 

C-H ring stretching of 3-methylpyridine^57-60 appears at 3062 cm^-1 and 3031 cm^-1. Band at 3055 cm^-1 has been located in [3]. There is increase of ring C=N str.&ring C=N torsion values and decrease of ring C-H bending mode values, which show presence of some Mo(dπ)→N(pπ) back bonding. A strong band at 977 cm^-1 is suggestive of terminal Mo=O^{45, 49, 50} in [3] (Table-4).

Table 4: FTIR absorptions in cm⁻¹

Table 4: (FTIR absorptions in cm−1)
Assignments	3-Methylpyridine57-60	[3]
C-H Ringstr.	3062, 3031	3397.2 s, 3055.8sh
C-H Methylstr.	3000, 2959, 2926	2867.8 sh
Ringstr.	1598, 1579	1630.5 m, 1552.7 m
Ring C-H bending	1480
C-H Methyl assym bending	1457, 1450	1469.5 m
Ring C-Hbending	1416
C-H methylsym. bending	1386	1384.8 w
Ring C-Hbending	1363	1304.38 sh
Ring str.	1249	1263.4 w
C-C bond between ring and methylstr.	1229
Ring C-H bending	1192	1185.3sh
C-H methyl rocking	1126, 1045	1116.25 m
Ring out of plane bending	1031	1044.32 w, 1027.32 w
RingC=N str.	791	890.5 vs, 785.3 m, 737.4
RingC=N torsion	712	723.6 m
Ring bending	636, 538	676.7 m, 511.9 w
∂ C-C bond between ring and methyl	456	464.2 w
Terminal Mo=O45, 49, 50str.		977.0 w

 

C-H ring stretching of 4-methylpyridine ^53-60 appears at 3074 cm^-1 and 3032 cm^-1. Band at 3097 cm^-1 has been located in [4]. There is increase of ring C=N str.&ring C=N torsion values and decrease of ring C-H bending mode values, which show presence of some Mo(dπ)→N(pπ) back bonding. A strong band at 976 cm^-1 is suggestive of terminal Mo=O ^{45, 49, 50} in [4] (Table-5).

Table 5:  (FTIR absorptions in cm⁻¹)

Table 5:  (FTIR absorptions in cm−1)
Assignment	4-Methylpyridine57-60	[4]
C-H Ringstr.	3074, 3032	3400.9 vs, b, 3097.5 sh
C-H Methylstr.	2992, 2926	2948.8 sh
Ringstr.	1610, 1563	1640.3 s, 1508.0m
Ring C-H bending	1501
C-H Methyl assym bending	1458, 1445	1444.7 sh
Ring C-H bending	1418
C-H methyl sym. bending	1383	1379.6 w
Ring C-H bending	1365	1316.0 w
Ring str.	1227	1256.0 w
C-C bond between ring and methyl str.	1210	1204.0 w
Ring C-H bending	1194
C-H Methyl rocking	1114, 1072	1113.4 w, 1039.6 w
Ringout of plane bending	995, 875
Ring C=N str.	730	793.8 m, 738.0 m
Ring C=N torsion	524	569.1 sh
∂ C-C bond between ring and methyl	486	476.5 w
Terminal Mo=O45, 49, 50str.		976.1s

 

¹H NMR Spectra

CH₂ peaks of succinimide^{61, 62} absorb at 2.74 ppm. ¹H NMR of [1] in DMSO-d₆ shows CH₂ peaks at 2.63 ppm showing upfield shift (Table-6). ↑ and ↓ represent upfield/downfield shift.

Table 6: (¹H NMR absorptions in ppm)

Table 6: (1H NMR absorptions in ppm)
Assignments	Succinimide61, 62 in CDCl3	[1]
N-H	8.9	11.12 ↓
CH2	2.75	2.63↑
Residual63 DMSO-d6		2.57
THF63 C-2, 5		3.51
THF63 C-3, 4

 

Imidazole ^{64, 65} spectrumin shows C-H proton (in middle ofnitrogen atoms) absorption at 7.72 ppm.Remaining C-H protons absorb at 7.14 ppm. N-H absorption occurs at 11.60 ppm. Spectrum of [2] in DMSO-d₆ shows relatively downfield absorptions for all the protons due to coordination of ligand lone pairs with Mo cations (Table-7). Two equivalent C–H protons of imidazole appear as singlets, because of the tautomerization equilibrium.

Table 7: (¹H NMR absorptions in ppm)

Table 7: (1H NMR absorptions in ppm)
Assignments	Imidazole64, 65 in CDCl3	[2]
N-H	11.60 1H	14.94 (b) 2H ↓
C-H (in middle of nitrogen atoms)	7.72 1H	9.21 (s) 1H ↓
C-H (remaining)	7.14 2H	7.74 (s) 2H ↓
Residual63 DMSO-d6		2.58 (s)
THF63 C-2, 5		3.63 (s) 4H
THF63 C-3, 4

 

On comparison of ¹H NMR of 3-methylpyridine ^{58, 59, 66} with that of [3], it is observed that these absorptions have moved downfield due to decrease in π-electron density of the ring on lone pair sharing bynitrogen with molybdenum cation (Table-8).

Table 8: (¹H NMR absorptions in ppm)

Table 8: (1H NMR absorptions in ppm)
Absorptions	3-Methylpyridine58, 59, 66  in CDCl3	[3]
H (CH3)	2.32 3H Singlet	2.57 ↓
H-C1	8.44 1H Singlet	8.891H ↓
H-C3	7.45 1H Doublet	8.47 1H ↓
H-C4	7.16 1H Triplet	8.01 ↓
H-C5	8.42 1H Doublet	8.83↓
Residual63 DMSO-d6		2.58
THF64 C-2, 5		3.65
THF65 C-3, 4		1.56

On comparison of ¹H NMR of 4-methylpyridine ^{58, 59, 66} with that of [4]it is observed that these absorptions have moved downfield due to decrease in π-electron density of the ring on lone pair sharing by nitrogen with molybdenum cation(Table-9).

Table 9: (¹H NMR absorptions in ppm)

Table 9: (1H NMR absorptions in ppm)
Assignments	4-Methylpyridine58, 59, 66 in CDCl3	[4]
H (CH3)	2.34 3H s	2.58↓
H-C1& H-C5	8.46 2H d	8.78↓
H-C2 & H-C4	7.10 2H d	7.88↓
Residual63 DMSO-d6		2.50
THF63 C-2, 5		3.32
THF63 C-3, 4		1.49

 

¹³C NMR Spectra

On comparison of ¹³C NMR of succinimide⁶⁷ with that of [1], it is observed that these absorptions have moved slightly upfield (Table-10).

Table 10: (¹³C NMR absorptions in ppm)

Table 10: (13C NMR absorptions in ppm)
Assignments	Succinimide67	[1]
C attached to oxygen	183.85	179.30 singlet ↑
Other C	30.30	29.41 singlet ↑
Residual68 DMSO-d6		39.37 pentet ↑
THF69 C-2, 5
THF69 C-3, 4

 

Microbiological Activity

Molybdenum compounds prepared were tested for their antibacterial and antifungal activities with strains: gram-positive bacteria Staphylococcus aureus (MTCC-737), gram-negative bacteria E. coli (MTCC-1687), fungi Candida albicans (MTCC-227) and Aspergil lusniger (MTCC-282).Reference drugs amoxicillin and ketoconazole were used for bacteria and fungi, respectively. Zone of inhibition⁷⁰ for a strain of bacteria/fungi has been measured to find out extent of resistance of bacteria/fungi to the reference drug.Molybdenum compounds have been observed potentially active against bacteria and fungi (Table-11).Especially,

Compounds 1, 2, 3 and 4 have greater antibacterial potential against E. coli than the reference drug (amoxicillin).

Compounds 3 and 4 have greater antifungal potential against C. albicansthan the reference drug (ketoconazole).

Table 11: (Microbiological Study)

Table 11: (MicrobiologicalStudy)
Compound(100 µg/ml)	Zone of inhibition63(mm)
	Gram- positive	Gram- negative	Antifungal
	S. aureus	E. coli	C. albicans	A. niger
Reference Drug	25.69	18.35	21.37	28.21
[1]	21.38	19.51	18.54	21.29
[2]	18.63	21.41	19.66	22.51
[3]	21.41	21.36	22.57	19.12
[4]	19.36	21.58	22.32	18.74
Solvent control	—	—	—	—
Conclusion and results	These compounds can kill and inhibit the growth of microbes

 

Mass Spectra (LC-MS)⁷¹

Ionic speciesnoted (Tables-12, 13)justify the formulae,

Table 12: (LC-MS Ionization) Click here to View table

Table 13: (LC-MS Ion m/z values)

Table 13: (LC-MS Ion m/z values)
Comp.	Ion	Calculated71	Detected	Relative  intensity
[1]	[MoO2Cl4(C4H8O)(C4H5NO2)3]2+	319.46	321.11	15
	[MoO2Cl4(C4H8O)(C4H5NO2)4]+	737.95	737.54	2%
	[MoOCl4(C4H8O)]+	325.83	327.11	42%
	[MoOCl2(C4H5NO2)2(C4H8O)]2+	226.97	230.07	36%
	[C4H5NO2]+	99.03	100.05	52
	[C4H8O]+	72.05	73.07	13
	[MoOCl2]2+	91.91	91.04	100
	[MoO2Cl4(C4H8O)]2+	170.91	172.11	8%
[2]	[Mo2O12Cl7(C3H4N2)7]2+	554.40	555.38
	[Mo2O4Cl6(C3H4N2)6]2+	438.91	440.05	7%
	[Mo2O4Cl2(C3H4N2)6]2+	368.97	371.99	12%
	[Mo2O4Cl2(C3H4N2)4]2+	300.93	303.94	3%
	[Mo2O4Cl2(C3H4N2)2]2+	232.90	235.18	2%
	[Mo2O4Cl2]2+	164.86	163.10	8%
	[MoOCl2]2+	91.91	91.04	10
	[C3H4N2]+	68.03	69.04	100
[3]	[Mo3Cl8(C6H7N)4(C4H8O)2]2+	544.90	544.46	3%
	[Mo3Cl8)(C6H7N)4]2+	472.84	472.39	4
	[MoCl6)(C6H7N)]+	400.77	400.32	5%
	[MoCl4)(C6H7N)]+	330.83	328.25	10%
	[C6H7N]+	93.05	94.06	100
	[C4H8O]+	72.05	73.07	8
[4]	[Mo3Cl8(C6H7N)4(C4H8O)2]2+	544.90	544.47	6%
	[Mo3Cl8)(C6H7N)4]2+	472.84	472.39	8%
	[MoCl6)(C6H7N)]+	400.77	400.32	18%
	[MoCl4)(C6H7N)]+	330.83	328.26	18%
	[C6H7N]+	93.05	94.06	100%
	[C4H8O]+	72.05	73.07	3%

 

Conclusion

Band at 3434 cm^-1 suggests the presence of N-H group in [1]. Stretching at 938 cm^-1 and 918 cm^-1 reveal the existence of cis-MoO₂²⁺ corein [1]. C=O frequency has not altered much from 1773 cm^-1 and 1711 cm^-1, indicating thereby absence of Mo–O coordination in [1]. There seems to be little decrease in C=O bond order. ¹H NMR of [1]shows CH₂ peaks at 2.63 ppm showing up field shift.¹³ C NMR of [1] shows that the absorptions have moved slightly up field. Compound is potentially active against microbes. Detection of ions in LC-MS are in tune with the formula presented.

There is presence of broad band at 3431 cm^-1-3000 cm^-1 pertaining to N-H group in [2]. This broadening occurs in the solid state (KBr disk) because of hydrogen bonding. A strong band at 975 cm^-1 is suggestive of terminal Mo=O in [2]. Imidazole spectrum shows C-H proton (in middle of nitrogen atoms) absorption at 7.72 ppm. Remaining C-H protons absorb at 7.14 ppm. N-H absorption occurs at 11.60 ppm. Spectrum of [2] shows relatively downfield absorptions for all the protons due to coordination of ligand lone pairs with Mo cations. Two equivalent C–H protons of imidazole appear as singlets because of the tautomerization equilibrium. Compound is potentially active against microbes.Detection of ions in LC-MS are in tune with the formula presented.

Band at 3055 cm^-1 has been located in [3]. There is increase of ring C=N str. and ring C=N torsion values and decrease of ring C-H bending mode values, which show presence of some Mo(dπ)→N(pπ) back bonding. A strong b and at 977 cm^-1 is suggestive of terminal Mo=O in [3]. It is observed that these proton absorptions have moved downfield due to decrease in π-electron density of the ring on lone pair coordination by nitrogen with molybdenum cation.Compound is potentially active against microbes.Detection of ions in LC-MS are in tune with the formula presented.

Band at 3097 cm^-1 has been located in [4]. There is increase of ring C=N str. and ring C=N torsion values and decrease of ring C-H bending mode values, which show presence of some Mo(dπ)→N(pπ) back bonding. A strong band at 976 cm^-1 is suggestive of terminal Mo=O in [4]. It is observed that these proton absorptions have moved downfield due to decrease in π-electron density of the ring on lone pair coordination by nitrogen with molybdenum cation.Compound is potentially active against microbes.Detection of ions in LC-MS are in tune with the formula presented.

Acknowledgement

P. U. Chandigarh, India is acknowledged for providing characterizing facility.

Conflict of Interest

Authors have no conflict of interest.

References

1. Shetgiri, N.P.;Nayak,B.K.,Indian J. Chem., 2005, 44B, 1933-1936.
2. Hall, I. H.; Wong, O. T.; Scovill, J. P.,Biomed Pharmacother,1995, 49(5), 251-258.
   CrossRef
3. Aeberli, P; Go gerty, J. H; Houlihan, W. J; Iorio, L. C.,J. Med. Chem.,1976, 19(3), 436-438.
   CrossRef
4. Rich, D. H.; Gardner, J. H.,Tetrahedron Letters, 1983, 24(48), 5305-5308.
   CrossRef
5. Pennington, F. C.; Guercio, P. A.; Solomons, I. A.,J. Amer. Chem. Soc., 1953, 75(9), 2261.
   CrossRef
6. Correa, R.; Filho, V. C.; Rosa, P. W.; Pereira, C. I.; Schlemper, V.; Nunes, R. J.,Pharm. Pharmacol. Comm., 1997, 3(2), 67-71.
7. Crider, A. M; Kolczynski, T. M.; Yates, K. M., J. Med. Chem.,1980, 23(3), 324-326.
   CrossRef
8. Kaczorowski, G. J.; McManus, O. B.; Priest, B. T.; Garcia, M. L., Gen. Physiology, 2008, 131(5), 399-405.
   CrossRef
9. Filho, V. C.; Nunes, R. J.; Calixto, J. B.; Yunes, R. A., Pharm. Pharmacol. Comm., 1995,1(8), 399-401.
10. Johnston, T. P.; Piper, J. R.; Stringfellow, C. R.,J. Med. Chem.,1971, 14(4), 350-354.
    CrossRef
11. Musso, D. L.; Cochran, F. R.; Kelley, J. L.; McLean, E. W.; Selph, J. L.; Rigdon, G. C., J. Med. Chem., 2003, 46(3), 399-408.
    CrossRef
12. Zentz, F.; Valla, A.; Guillou, R. L.; Labia, R.; Mathot, A. G.; Sirot, D.,Farmaco, 2002, 57(5), 421-426.
    CrossRef
13. Hazra, B. G.; Pore, V. S.; Day, S. K.; Datta, S.; Darokar, M. P., Saikia, D.,Bioorg. Med. Chem. Lett., 2004, 14(3), 773-777.
    CrossRef
14. Kornet, M. J.; Crider, A. M.; Magarian, E. O., J. Med. Chem., 1977, 20(3), 405-409.
    CrossRef
15. Isaka, M.; Prathumpai, W.; Wongsa, P.; Tanticharoen, M.; Hirsutellone, F.,Org. Lett.,2006, 8(13), 2815-2817.
    CrossRef
16. Katritzky, A. R.; Rees,Comprehensive Heterocyclic Chemistry, 1984, 5, 469-498.
    CrossRef
17. Grimmett, M. R., Imidazole and Benzimidazole Synthesis, Academic Press, 1997.
    CrossRef
18. Brown, E.G., Ring Nitrogen and Key Biomolecules, Kluwer Academic Press, 1998.
19. Pozharskii, A.F., Soldatenkov, A. T.; Katritzky,A. R.,Heterocycles in Life and Society, John Wiley & Sons, 1997.
20. Gilchrist, T. L., Heterocyclic Chemistry,the Bath Press,1985, ISBN 0-582-01421-2.
21. Congiu, C.;Cocco, M. T.;Onnis, V.,Bioorganic & Medicinal Chemistry Letters, 2008, 18, 989–993.
22. Venkatesan, A.M.;Agarwal, A.;Abe, T.;Ushirogochi, H.O.;Santos, D.;Li, Z.;Francisco, G.;Lin, Y.I.;Peterson, P.J.;Yang, Y.;Weiss, W.J.;Shales, D.M.;Mansour, T.S.,Bioorg. Med. Chem., 2008, 16, 1890-1902.
    CrossRef
23. Nakamura, T.;Kakinuma, H.;Umemiya, H.;Amada, H.;Miyata, N.;Taniguchi, K.;Bando, K.;Sato, M.,Bioorganic & Medicinal Chemistry Letters, 2004, 14, 333-336.
    CrossRef
24. Han, M. S.; Kim, D. H., Bioorganic & Medicinal Chemistry Letters, 2001, 11, 1425- 1427.
    CrossRef
25. Roman, G.;Riley, J.G.;Vlahakis, J. Z.;Kinobe, R.T.;Brien, J.F.;Nakatsu, K.;Szarek,W.A., Bioorg. Med. Chem., 2007, 15, 3225-3234.
    CrossRef
26. Bbizhayev, M. A., Life Sci., 2006, 78, 2343-2357.
    CrossRef
27. Nantermet, P.G.;Barrow, J.C.;Lindsley, S.R.;Young, M.;Mao, S.;Carroll, S.;Bailey, C.;Bosserman, M.;Colussi, D.;McMasters, D.R.;Vacca, J.P.;Selnick, H.G.,Bioorg. Med. Chem. Lett.,2004, 14, 2141-2145.
    CrossRef
28. Adams, J. L.;Boehm, J.C.;Gallagher, T. F.;Kassis, S.;Webb, E. F.;Hall, R.;Sorenson, M.; Garigipati, R.;Griswold, D. E.; Lee,J. C.,Bioorg.Med. Chem.Lett., 2001,11,2867-2870.
    CrossRef
29. https://en.wikipedia.org/wiki/3-Methylpyridine.
    CrossRef
30. Shimizu, S.;Watanabe, N.;Kataoka, T.;Shoji, T.;Abe, N.;Morishita, S.;Ichimura. H.,Ullmann’s Encyclopedia of Industrial Chemistry, 2002, doi:10.1002/14356007.a22_399.
    CrossRef
31. Sims, G. K.;Sommers, L.E.,Environmental Toxicology and Chemistry, 1986, 5, 503-509.
    CrossRef
32. Sims, G. K.;Sommers, L. E.,J. Environmental Quality,1985, 14, 580-584.
    CrossRef
33. https://www.alfa.com/en/catalog/A14012/.
34. https://en.wikipedia.org/wiki/4-Methylpyridine.
35. https://pubchem.ncbi.nlm.nih.gov/compound/4-Methylpyridine #section= Chemical-Vendors.
36. Thomas, D. D.; Ridnour, L. A.; Isenberg, J. S.; Flores, S. W.; Switzer, C. H.; Donzelli, S.; Hussain, P.; Vecoli, C.; Paolocci, N.; Ambs, S.; Colton, C. A.; Harris, C. C.; Roberts, D. D.; Wink, D. A., Free Radical Biology and Medicine, 2008, 45(1), 18-31.
    CrossRef
37. Chen, P. R.; He, C.,Current Opinion in Chemical Biology, 2008, 12(2), 214-21.
    CrossRef
38. Pennella, M. A.; Giedroc, D. P.,Biometals, 2005, 18(4), 413-28.
    CrossRef
39. Cowan, J. A.; Bertini, I.; Gray, H. B.; Stiefel, E. I.; Valentine, J. S., Structure and Reactivity: Biological Inorganic Chemistry, 3, University Science Books, Sausalito,2007, 8(2): 175181.
40. Jameel, A.;MSA, S. A. P., Asian Journal of Chemistry, 2010, 22(12), 3422-48.
41. Anupama, B.; Sunuta, M.; Leela, D. S.; Ushaiah; Kumari, C. G.,Journal of Fluorescence, 2014, 24(4), 1067-76.
    CrossRef
42. Singh, G.; Mangla, V.; Goyal, M.; Singla, K.; Rani, D., American International Journal of Research in Science, Technology, Engineering & Mathematics, 2014, 8(2), 131-136.
43. Singh, G.; Mangla, V.; Goyal, M.; Singla, K.; Rani, D., American International Journal of Research in Science, Technology, Engineering & Mathematics, 2015,10(4),299-308.
44. Singh, G.; Mangla, V.; Goyal, M.; Singla, K.; Rani, D., American International Journal of Research in Science, Technology, Engineering & Mathematics, 2015,11(2),158-166.
45. Singh, G.; Mangla, V.; Goyal, M.; Singla, K.; Rani, D.; Kumar, R., American International Journal of Research in Science, Technology, Engineering & Mathematics, 2016, 16(1), 56-64.
46. Singh, G.; Kumar, R., American International Journal of Research in Science, Technology, Engineering & Mathematics, 2018, 22(1), 01-08.
47. Rani, D.; Singh, G.; Sharma, S., Oriental Journal of Chemistry, 2020, 36(6), 1096-1102.
    CrossRef
48. Vogel, A. I., A Text Book of Quantitative Inorganic Analysis; John Wiley and Sons: New York, (Standard methods)1963.
    CrossRef
49. Stamboliyska,B.A.;Binev, Y. I.; Radomirska, V. B.; Tsenov, J. A.; Juchnovskiet,I. N., Journal of Molecular Structure, 2000, 516, 237-245.
50. Uno, T.;Machida, K.,Bulletin of the Chemical Society of Japan, 1962, 35(2),276-283.
51. Heyn, B.; Hoffmann; Regina, Z. Chem.,1976, 16, 407.
    CrossRef
52. Abramenko, V.L.;Sergienko, V.S.;Churakov, A.V.,Russian J. Coord. Chem., 2000, 26(12), 866-871.
53. Abod, N. A.; M. AL-Askari; Saed, B. A., Basrah Journal of Science (C),2012, 30(1), 119-131.
54. Mohan, J., Organic Spectroscopy: Principles and Applications, CRC Press, 2004.
55. Barraclough, C. G.; Kew, D. J., Australian J. Chem., 1970, 23, 2387-2396.
    CrossRef
56. Ward, B. G.; Stafford, F. E., Inorg. Chem.,1968, 7, 2569.
    CrossRef
57. Toco’n, I. L.;Woolley, M.S.;Otero, J.C.;Marcos, J. I.,Journal of Molecular Structure, 1998, 470, 241-246.
    CrossRef
58. Gupta, S. K.; Srivastava, T. S., J. Inorganic and Nuclear Chem., 1970, 32, 1611-1615.
    CrossRef
59. Hossain, A. G. M. M.; Ogura, K., Indian J. Chem., 1996, 35A, 373-378.
60. Brewerp,D. G.;Wong, P. T. T.;Sears, M. C.,Canadian J. Chem., 1968, 46(20), 3119-3128.
    CrossRef
61. https://www.chemicalbook.com/SpectrumEN_123-56-8_1HNMR.htm.
62. http://www.molbase.com/moldata/2973-spectrum.html.
63. http://isotope.com/uploads/File/new_datachart.pdf.
64. Pekmez, N. Ö.; Can, M.; Yildiza, A., Acta Chim. Slov., 2007, 54, 131-139.
65. Wanga, X.;Heinemanna F. W.; Yangb, M.;Melcherc, B. U.;Feketec, M.;Mudringb, A. V.; Wasserscheidc, P.;Meyera, K., Supplementary Material (ESI) for Chemical Communications, The Royal Society of Chemistry, 2009.
66. Kumari, N.; Sharma, M.; Das,, P.; Dutta, D. K., Applied Organomet. Chem., 2002, 16, 258-264.
    CrossRef
67. https://www.chemicalbook.com/SpectrumEN_123-56-8_13CNMR.htm.
68. https://en.wikipedia.org/wiki/Deuterated_DMSO#:~:text=Pure%20deuterated%20DMSO%20shows%20no,is%2039.52ppm%20(septet).
69. https://www.chemicalbook.com/SpectrumEN_109-99-9_13cnmr.htm.
70. https://sciencing.com/measure-zone-inhibition-6570610.html.
71. http://www.sisweb.com/referenc/tools/exactmass.htm.

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