analytical properties of 2,2' bis(di 2 pyridinyl methylene) thiocarbohydrazone

8/13/2019 Analytical Properties of 2,2' Bis(Di 2 Pyridinyl Methylene) Thiocarbohydrazone

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Analytical Properties of 2,2-Bis(di-2-pyridinyl-methylene)-thiocarbohydrazone

J. R. BONILLA ABAs~AL., A. GARCIA DE TORRES, ANDJ. M. CANO PAVON

Thiosemicarbazones have been widely used as analytical reagents inspectrophotometry, fluorimetry, and also as visual indicators. Their ana-lytical applications have been reviewed (II). In general, the great abilitythat the atoms of sulfur have for coordinating metal cations makes theestablishment of selective methods of analysis difficult; however, due tothe acid dissociation of the thiosemicarbazone group, formation of che-lates is pH-dependent. This fact, as well as the use of masking agents,have been used in diverse selective determinations for some metal ions,such as copper with biacetyl-bis (4-phenyl-3-thiosemicarbazone) (I) andI,2 cyclohexonodione bis thiosemicarbazone (9), manganese with biacetyloxime (4-phenyl-3-thiosemicarbazone) (3), and divcrsc mixtures of cobalt,nickel, iron, and copper with picolinaldehyde thiosemicarbazone (4).

In our department, a study has begun about the complexing propertiesand analytical applications of thiocarbohydrazones. These compoundsshow a symmetrical structure and they are obtained by the condensationof thiocarbohydrazide,

H,N-NH- C-NH-NH,

with an aldehyde or ketone. No analytical data have been published onthese compounds, although they have been tested as antimicrobial andantitumor agents with good results (10).

I Actual address: Department of Analytical Chemistry, Faculty of Sciences, The Univer-sity. Malaga.


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134 BONILLA ABASCAL, GARCIA DE TORRES, AND CAN0 PAVON

TABLE 1PHYSICOCHEMI~AL PROPERTIES OFDPTH

Solubility in water (griliter)Solubility in ethanol (griliter)Solubility in amyl alcohol (griliter)Solubility in dimethylformamide (griliterlSolubility in chloroform (griliter)-NH- Frequency (cm-)-C=N- Frequency (cm-)-C=S- Frequency (cm-)First pK found

(Stenstrom and Goldsmith method)Second pK found

(Stenstrom and Goldsmith method)

0.0721.0680.256

11.1125.2

3060 w1590 m, 1580 m1230 s, 1210 m

3.07

9.85

water. The absorbance was measured at 350-700 nm against reagentblanks. The most important results are summarized in Table 2.

RESULTS AND DISCUSSION

DPTH shows only two ionization steps. Since the molecule is symmet-rical and the distance between the four nitrogen atoms of the pyridinerings is relatively long, the values of the constantsK1 to K, would beexpected to lie close together, and are not distinguishable by spec-

TABLE 2CHARACTERISTICS OF DPTH COMPOUNDS

Ion Optimum pH

Co(H) 3.2 Yellow 410 5.29 x lo

Co(lI) 10.4- 11.0 Red 480 4.28 x lo*Ni(II1 4.8-6.8 Yellow 410 5.01 x 10Cu(l1) 2.4-4.8 Yellow 420 2.80 x 10Zn(I1) 6.2-9.8 Yellow 415 6.01 x 10Cd(H) 5.8-8.3 Yellow 415 5.64 x IO4Fe(II1 3.0-55.0 Green 670 0.92 x 104&(I) 9.5 Yellow 420 1.18 x 104Fe(II1) 5.5 Yellow 410 5.42 x 10Os(IV1 1.7 Yellow 414 1.23 x 10Hs(I) 5.5 Yellow 412 2.39 x IOHg(IIJ 5.5 Yellow 404 4.51 x 104

Pb(IJ1 9.5 Yellow 430 1.99 x 104Bi(III) 5.5 Yellow 420 5.33 x IO-1Pd(IJ) 3.0 Yellow 414 2.92 x IO4WV) 2.3 Yellow 450 1.32 x 104In(IV1 5.5 Yellow 420 4.51 x IOGa(II1) 5.5 Yellow 420 3.07 x 101

nm liter, moles .crn-i M:R

I:2

1: II:2I:II:3I:3I:?-


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ANALYTICAL PROPERTIES OF THIOCARBOHYDRAZONE 135

trophotometry: the value found is 3.07; this value resembles the corre-sponding constants of pyridine rings (2,6). The second pK value found is

9.85, and can be attributed to the loss of the proton of the -SH group (5).DPTH is unstable towards strong oxidizing agents, but stable in the

presence of reducing substances, and it is not hydrolyzed by acids, andcan be used in acidic solutions.

Stoichiometric data show that DPTH acts as a tridentate ligand withconvenient steric arrangements of its donor groups in the complexesformed with Co(II), Ni, and Fe(lI), and as a bidentate ligand againstCu(II), Zn, and Cd. These data indicate that each half of the moleculebehaves independently, and that the grouping thioazomethineferroine

N=C-C=N-N=C-

S

is used in the coordination as occurs in the complexes of cu-pyridylthiosemicarbazones (7). In the case of the red cobalt-DPTH complex inalkaline media, the 1:l stoichiometric ratio seems to indicate that DPTHacts as a sexadentate ligand, with no participation of the sulfur atom.

The analytical possibilities of DPTH are superior to those of di-2-pyridyl ketone thiosemicarbazone (DPKT) (8) owing to the higher molar

2 +-------4 Ni

I--- - -- ----lct-----4 co

- Fe(ll)

2 4 6 6 IO 12 PH

F~ti. 1. Comparison of molar absorptivity (in liters.mol cm .) and optimum pH rangeof the complexes of DPTH (---I and DPKT (- - -).


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136 BONlLLA ABASCAL. GARCIA DE TORRES, AND CAN0 PAVON

absorptivities of the chelates and to the shift of the absorption peaks tolonger wavelengths. Figure 1 summarizes for comparison the optimal pH

zones for the formation of the complexes with DPTH and DPKT as wellas the molar absorptivity. In general, the optimal pH range of DPTHcomplexes lies at more acidic pH values, and their molar absorptivityhave the highest values. Zn and Cd form orange-yellow complexes thatcan be used in the spectrophotometric determination of both ions at verylow concentrations.

SUMMARYThe synthesis and analytical properties of 2.2-bis (di-?-pyridinyl-methylene)-

thiocarbohydrazone are described. The solubility, spectral characteristics, and pK valuesare reported, as well as the absorptivity and stoichiometric ratio of metal chelates formed.

REFERENCESI. Asuero, A. G., and Cano, J. M., Biacetyl bis (4.phenyl-3-thiosemicarbazone) as a re-

agent for the spectrophotometric determination of copper. At~crl~~r 103, 140- 148(1978).

2. Brown, H. C., and McDaniel, D. H., The base strengths and ultraviolet absorptionspectra of the 2- and 3-monohalopyridines. J. Amrr. Chem. SW. 77, 3752 (1955).

3. Cano Pavon, J. M.. Jimenez Sanchez. J. C., and Pino, F., The 4-phenyl-3-

thiosemicarbazone of biacetylmonoxime as an analytical reagent. Spectrophotometricdetermination of manganese. AIILI/. Chim. Acru. 75, 335(1975).

4. Cano Pavon, J. M., and Perez Bendito, Determination fotometrica de Fe, Co. Ni, y Cu.en mezclas con la tiosemicarbazona del picolinaldehido. /,I, Qrtin~.AMJ/. 27, 20-30(1974).

5. Cano Pavon. J. M., and Pino, F., Comparative study of analytical properties and appli-

cations of picolinaldehyde thiosemicarbazone and selenosemicarbazone. 7a/tr/?tc1 19,

1659% 1663 (1972).6. Gonzalez Balairon, M.. Cano Pavon, J. M., and Pino. F., Analytical properties of

bipyridylglyoxal bis (4.phenyl-3-thiosemicarbazone). Tu/art/ tr 26, 71-73 (1978).7. Martinez Aguilar. M. T.. Cano Pavon, J. M., and Pino, F., The thioazomethine-fer-

roine group as a new functional group for iron( Determination of iron with 2-acetylpyridine-4-phenyl-3-thiosemicarbazone. 90, 335-338 (1977).

8. Martinez, M. P.. Valcarcel, M., and Pino, F., Di-2-pyridyl ketone thiosemicarbazone asan analytical reagent. Ancrl. Chinl. Ado 81, 157 (1976).

9. Mutioz Leyva, J. A.. Cano Pavon, J. M., and Pino, F., Empleo de la 1.2 cic-lohexanodiona ditiosemicarbazona coma reactive espectrofotometrico para la deter-minacion selectiva de cobre en disolucibn. An. Quim. 72, 392-395 (1976).

10. Rhee, S., Synthesis and evaluation of antimicrobial-antitumur activities of methyl-thiosemicarbazones and thiocarbohidrazones. J. Pllcrrrn. SW. Korc,cr 16, 162- 175(1972).

/I. Singh, R. B., Garg. D. S., and Singh. R. P., Analytical applications of thiosemicar-bazones and semicarbazones: A review. T~/rrl ltrr 25, 619 (1978).

12. Stenstrom and Goldsmith, Determination of the dissociation constants of phenol and thehydroxyl group of tyrosine by means of absorption measurements in the ultraviolet. .I.Phys. Chem. 30, 1683 (1926).

analytical properties of 2,2' bis(di 2 pyridinyl methylene) thiocarbohydrazone

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