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Study of the reaction of dextran with copper ions
STUDY OF THE REACTION OF DEXTRAN WITH COPPER IONS* V. N. TOLMACHEV, Z. A. LUGOVAYA,I. K. ISHCHEENEO, A. I. VALAKHANOVICH and V. U. ZABORONOK A. M. Gor’kii
State University,
(Received
Studies containing weight
ions, in relation
composite
metrically
compounds
and
by
and viscosity
to medium
of copper
equilibrium
1973)
12 October
were made of the spectra copper
Khar’kov
of aqueous
pH.
with
dextran
of dextran
of high molecular
was examined
Corresponding
dialysis.
solutions
The formation constants
spectrophotowere
calculated.
CONSIDERABLE attention is now being given to the study of composite compounds formed by the interaction of metal ions with macromolecular ligrtnds. Dextran is known to be able to combine with many metal ions in solution. According to the molecular weight of dextran, degree of substitution of hydroxyl groups in its molecule and the type of functional groups introduced, the compounds formed have different properties. This paper deals with the interaction of dextran with copper ions in aqueous solutions. The
industrial
glycopyranose to the extent By weight
clinical
units
of which
precipitation weights
7=9*66
(in the form Ionic
Dialysis
ment
the Na,SO* diffused.
accelerate
a homopolysaccharide extent
consisting
of 93-94s
of
and
1,4-bonds,
The
* Vysokomol.
carried
viscosity
molecular
soyed.
weights
viscometrically
of 25,000 and
and calculated
and dextran
x lo-$ mole/l.,
by Na,SO1.
by
To obtain
for the viscosity
consisting
contains
solution
the
of the same concentration in the dialyser
of equilibrium.
which
were vigorously
The concentration
A17: No. 2, 419-422, 486
1975.
Spectro-
spectrophotome-
of two with
is contained. copper
100 ml
pH values
measurement.
in a dialyser
through
1.62 g per
the requisite
SF-4-A and IKSl4A
which is used as inert electrolyte.
membrane,
ions were constant:
dextran
was made using a glass electrode.
out using
was applied
compartment
solutions
determination
molecular
of copper
pH measurement
sulphate
solution
the average
with
at 25+0.1’
CuSO, .5H,O)-5
[3] was studied
One
dextran,
prepared
[2].
were
viscometer
equilibrium
ions and sodium
the initial were
(0.1) was conferred
used as a semi-permeable freely
to the
the concentrations
was added.
compartments.
copper
was
1,6-bohds
determined
of solution
measurements
ters. An Ubbelohde glass
studied
strength
0.1 or 1.0 N NaOH photometric
were
x lo-’ x &P
In all solutions solution.
examined
from
is 56,000, fractions
43,000. Molecular
copper
wit,h
of 7% [l].
fractional
the formula
dextran
connected
the
identical
organic
polymer
ligand,
In the second compartA cellophane
ions uncombined agitated
and kept
of free copper
film was
with polymer at 50’ to
ions in the com-
Reaction of dextran with copper ions
487
partment containing Na,SO, solution was determined trilonometrically. Special experiments showed that the membrane used did not adsorb copper ions and dextran. The atrone method was used to control dextran content in solutions [a].
Figure 1 shows that initial components with a pH N 6 absorb to a negligible extent. On increasing pH, absorption bands appear in the range of 230-250 and 640-700 nm and their intensity varies. It may be assumed that in the pH range of 6.5-7~5 coordination units are formed which absorb at 230 nm. In the pH range of 7-5-11 this absorption band is subject to bathochrome displacement and on further increasing pH, a hypsochrome shift occurs. Weak bands in the
FIU. 1. Absorption spectra of dextran-copper complexes at pH of 5.9 (1); 7.0 (2); 9.2 (3); 19.7 (4); 11.2 (5); 12.7 (6) and 13 (7). Absorption of initial dextran solutions of M=26,000 (CC) and copper (5). Layer thickness I in the UV range was 0.05 and in the visible range- 1 cm.
visible range (&=40) are probably due to d-d transitions [5]. Intense bands in the W range (a ~3000) may be attributed to bands of charge transfer, in this case from a dextran macro-ligand to a copper ion. The dependence of optical density D on pH (Fig. 2) confirms the possibility of gradual complex formation in the solutions studied.
488
V. N. TOLMACEEV et a?.
Viscosity measurements of these solutions with or without copper ions show that up to a pH of 8-9 viscosity varies in the same way (namely, increases). This is, apparently, due to the fact that dextran molecules shaped M spirals [S] are partially straightened.- Table 1 indicates that with pH>&9, viscosity decreases which may be due to the formation of dextran-copper complexes of different compositions. Table 1 also indicates that under the concentration conditions used copper ions were fully combined at a pH N 11 in all three samples. A comparison of these results with Figs. 1 and 2 shows that in the pH range of 5-13 on combi@ng copper ions with dextran macromolecules coordination units gradually TABLE 1. RESULTS OB VISCOSITY AND DIALYSIS STUDIES
--
Amount of com-
M x IO+
56
PH 5-3 7.2 9.0 9.1 10-l 10.6 10.8
43
5.8 6-3 7-6 8.6 9.6 11.2
25
5.9 6-l 7.9
8.2 9.2 9.9 10.7 11.2
tlSP
bined a; x
0.56 0.64 o-73 0.69 O-66 ' 0.62 0.61
copper,
103, mole/l. 0
o-45 2.35 3.90 4.70 4-95 4-80
0.55 0.56 Ov!SS 0.65 0.56 o-52
0 0.30 o-75 3.70 4.65 5.00
O-52 o-53 0.55 0.60 0.54 o-45 0.37 0.31
0 O-80 2.25 2.70 4-06 4.65 4.75 5.00
form, the transition starting with a pH of 8. Bearing in mind that dextran in alkaline medium may undergo oxidation [7], this transition may be due to the formation of new units with carboxyl groups. Indeed, our studies indicated that IR spectra of dextran and its copper complexes in alkaline medium contain absorption bands representing COOH groups. Bearing in mind these facts, further studies of complex formation of dextran with copper ions were carried out spectrophotometrically in the pH range of
Remtion
of dextran with
copper ions
489
D&ran does not oxidize under these conditions. Further, as indicated 6-8. previously, complexes are formed which absorb at &,,,=230 nm. It is also important to note that this pH range is interesting from a practical point of view. TABLE 2. RESULTS OF
DETERMINING
CONSTANTS
OF COMFLEX FOR-
MATION
-
-
-
D MxlO-*
PH
- 56
-
when
A=230
nm
1=0.45
cm
ax 104,
KxlO'a
mole/l.
-
6.50
0.65
5.41
7.6
6.65
1.10
9.26
14.0
6.70
9.25
12.0
10.50 11.67 12.17 12.42
13.3
7.10 7.25 7.50
1.12 1.26 1.40 1.46 1.49
6.60 6.80 6.90 7.10 7.45 7.80
0.63 0.82 1.05 1.22 1.50 1.58
4.14 6.41 8.20 9.53 11.72 12.34
6.45 6.65 6.80 7.00 7.05 7.25 7.75
0.56 om 1.10 1.33 1.35 1.47 1.59
4.37 6.87 8.62 10.39 10.54 11.48 12.42
6.80
8.9 9.4 15.6 11*5+2*7
43
3.1 2.7 3.1 2.0 1.9 2.0 2.5f0.6
25
-
6.8 6.2 5.6 5.0 4.3 3.5 4.2 5.1*1*1
L
Constants of complex formation were calculated by the Kuhn method. Absorption spectra were obtained under the same conditions, as described previously, however, copper concentration in solutions was reduced to 1.26 x X 10m3mole/l., which should ensure complete combination with dextran (Table 1). Dextran concentration was maintained at 1.62 g/dl which corresponds to O-1 base mole/l. Using our results and results derived from a study of copper-ammonium complexes of dextran [9] the reaction of dextran with copper ions may be decribed as R(OH),+CU”+P[CUR(O,H,-,,)I”-‘+RH+,
where R(OH), is the dextran unit.
(1)
V. N. TOLMACHEV et al.
a90
The equilibrium constant ,
,=[CuR(~,H,-~)l”-“[Hfln
’(2)
~~2+I13(OWJ
Since, according to experimental conditions [R (OH),]> [(X2+], using logarithm with formula (2) we obtain In - x l-x
=const+npH,
where 2 is the relative content of the complex and n-the number of protons isolated by the reaction. Figure 3 shows curves of equation (3), from which it can be seen that for all de&ran samples studied n N 2, i.e. on combining one copper ion two protons are most probably separated from one dextran unit. In this case CW+ : R(OH), = 1 : 1. Results of calculating constants R are shown in Table 2. It follows from A 3.6 -
al 5
I
7
I
‘9 FIG. 2
I
II
I
13 pH
7.8
, pH
FIU. 3
FIQ. 2. Relationship between the optical density of solutions and pH at A=230 nm; M x 10-a =66 (I), 43 (2) and 26 (3). FIU. 3. Determining the value of n. The ordinate axis shows the logarithmic ratio of combined copper ion concentrations to the product of free copper ion concentrations and the overall concentration of dextran log c,/(c,-c,)c~=A.
equation (1) that these constants incorporate constants of acid dissociation of hydroxyl groups of de&ran. K is practically independent of medium pH. For an unfractionated sample (M=56,000) this constant is somewhat higher than for fractionated samples, however, K showed no signikant relation to molecular weight. Tra7aslatedby E. SEB53SE
Dielectric relaxation of imido-epoxide polymers
1. 2. 3. 4. 5. 6. 7. 8. 9.
491
T. V. POLUSHINA, Dissertation, 1968 V. Ya. CEfERNYAK and T. V. POLUSHINA, Med. prom&’ 8: 39, 1961 F. KARUSH and M. SONENBERG, J. Amer. Chem. Sot. 71: 1369, 1949 T. A. SCOTT and E. II. MELIN, Analyt. Chem. 25: 1656, 1953 6. LEWIS and R. WILKINSON, Sovremennaya khimiya koordinatsionnykh soyedinenii (Modern Chemistry of Coordination Compounds). Izd. inostr. lit., 1963 K. ZAKREWSKY, J. KRYSIAK, K. MURAWSKY, Z. MAY and J. MALEC, Acta biochim. polon. 1: 27, 1954 J. BREMNER, J. S. 6. COX and G. F. MOSS, Carbohydrate Res. 11: 77, 1969 W. KUHN and J. TOTH, Z. Naturforsch. Al& 112, 1963 T. A. SCOTT, N. N. HELLMAN and F. R. SENTI, J. Amer. Chem. Sot. 79: 1178, 1967
DIELECTRIC RELAXATION OF IMIDO-EPOXIDE POLYMERS HARDENED WITH ACID ANHYDRIDES* YE. A. BABENKOVA, T. I. BO~SOVA, N. A. NIKONOROVA
and G. A. SHTRAIKEI~ Institute of High Molecular Weight Compounds, U.S.S.R. Academy of Sciences (Receiwed 15 October1973)
A study was made of dielectric relaxation of polyimidoepoxide polymers prepared from IES-1 oligomer and anhydride type curing agents. It was shown that mechanisms of dielectric polarization are similar to those in epoxide polymers. The addition of imide groups increases kinetic rigidity of the molecular network.
MODIFICATION of epoxy resins by addition of heterocyclic elements to the oligomer involves the preparation of polymers with increased heat resistance and satisfactory electric and mechanical properties. This paper examines the relaxation behaviour of hardened polyepoxides containing arimide groups (PIE) using the dielectric loss method. Polymers prepared using stoichiometric mixtures of an IES-1 imido-epoxide oligomer [I] and tetrahydrophthalic acid anhydride (THPA) or dianhydride of resorcin b&(3,4dicarboxyphenyl ester) (RDA) without accelerators as curing agents, were examined. IES-1 w&s obtained by a two stage method. The ilrst stage of the reaction involved the preparation of amidoacid by interaction of trimellitic acid anhydride and metaphenylene
*Vysokomol. soyed. A17: No. 2, 423-428,
1975.
State University,
(Received
Studies containing weight
ions, in relation
composite
metrically
compounds
and
by
and viscosity
to medium
of copper
equilibrium
1973)
12 October
were made of the spectra copper
Khar’kov
of aqueous
pH.
with
dextran
of dextran
of high molecular
was examined
Corresponding
dialysis.
solutions
The formation constants
spectrophotowere
calculated.
CONSIDERABLE attention is now being given to the study of composite compounds formed by the interaction of metal ions with macromolecular ligrtnds. Dextran is known to be able to combine with many metal ions in solution. According to the molecular weight of dextran, degree of substitution of hydroxyl groups in its molecule and the type of functional groups introduced, the compounds formed have different properties. This paper deals with the interaction of dextran with copper ions in aqueous solutions. The
industrial
glycopyranose to the extent By weight
clinical
units
of which
precipitation weights
7=9*66
(in the form Ionic
Dialysis
ment
the Na,SO* diffused.
accelerate
a homopolysaccharide extent
consisting
of 93-94s
of
and
1,4-bonds,
The
* Vysokomol.
carried
viscosity
molecular
soyed.
weights
viscometrically
of 25,000 and
and calculated
and dextran
x lo-$ mole/l.,
by Na,SO1.
by
To obtain
for the viscosity
consisting
contains
solution
the
of the same concentration in the dialyser
of equilibrium.
which
were vigorously
The concentration
A17: No. 2, 419-422, 486
1975.
Spectro-
spectrophotome-
of two with
is contained. copper
100 ml
pH values
measurement.
in a dialyser
through
1.62 g per
the requisite
SF-4-A and IKSl4A
which is used as inert electrolyte.
membrane,
ions were constant:
dextran
was made using a glass electrode.
out using
was applied
compartment
solutions
determination
molecular
of copper
pH measurement
sulphate
solution
the average
with
at 25+0.1’
CuSO, .5H,O)-5
[3] was studied
One
dextran,
prepared
[2].
were
viscometer
equilibrium
ions and sodium
the initial were
(0.1) was conferred
used as a semi-permeable freely
to the
the concentrations
was added.
compartments.
copper
was
1,6-bohds
determined
of solution
measurements
ters. An Ubbelohde glass
studied
strength
0.1 or 1.0 N NaOH photometric
were
x lo-’ x &P
In all solutions solution.
examined
from
is 56,000, fractions
43,000. Molecular
copper
wit,h
of 7% [l].
fractional
the formula
dextran
connected
the
identical
organic
polymer
ligand,
In the second compartA cellophane
ions uncombined agitated
and kept
of free copper
film was
with polymer at 50’ to
ions in the com-
Reaction of dextran with copper ions
487
partment containing Na,SO, solution was determined trilonometrically. Special experiments showed that the membrane used did not adsorb copper ions and dextran. The atrone method was used to control dextran content in solutions [a].
Figure 1 shows that initial components with a pH N 6 absorb to a negligible extent. On increasing pH, absorption bands appear in the range of 230-250 and 640-700 nm and their intensity varies. It may be assumed that in the pH range of 6.5-7~5 coordination units are formed which absorb at 230 nm. In the pH range of 7-5-11 this absorption band is subject to bathochrome displacement and on further increasing pH, a hypsochrome shift occurs. Weak bands in the
FIU. 1. Absorption spectra of dextran-copper complexes at pH of 5.9 (1); 7.0 (2); 9.2 (3); 19.7 (4); 11.2 (5); 12.7 (6) and 13 (7). Absorption of initial dextran solutions of M=26,000 (CC) and copper (5). Layer thickness I in the UV range was 0.05 and in the visible range- 1 cm.
visible range (&=40) are probably due to d-d transitions [5]. Intense bands in the W range (a ~3000) may be attributed to bands of charge transfer, in this case from a dextran macro-ligand to a copper ion. The dependence of optical density D on pH (Fig. 2) confirms the possibility of gradual complex formation in the solutions studied.
488
V. N. TOLMACEEV et a?.
Viscosity measurements of these solutions with or without copper ions show that up to a pH of 8-9 viscosity varies in the same way (namely, increases). This is, apparently, due to the fact that dextran molecules shaped M spirals [S] are partially straightened.- Table 1 indicates that with pH>&9, viscosity decreases which may be due to the formation of dextran-copper complexes of different compositions. Table 1 also indicates that under the concentration conditions used copper ions were fully combined at a pH N 11 in all three samples. A comparison of these results with Figs. 1 and 2 shows that in the pH range of 5-13 on combi@ng copper ions with dextran macromolecules coordination units gradually TABLE 1. RESULTS OB VISCOSITY AND DIALYSIS STUDIES
--
Amount of com-
M x IO+
56
PH 5-3 7.2 9.0 9.1 10-l 10.6 10.8
43
5.8 6-3 7-6 8.6 9.6 11.2
25
5.9 6-l 7.9
8.2 9.2 9.9 10.7 11.2
tlSP
bined a; x
0.56 0.64 o-73 0.69 O-66 ' 0.62 0.61
copper,
103, mole/l. 0
o-45 2.35 3.90 4.70 4-95 4-80
0.55 0.56 Ov!SS 0.65 0.56 o-52
0 0.30 o-75 3.70 4.65 5.00
O-52 o-53 0.55 0.60 0.54 o-45 0.37 0.31
0 O-80 2.25 2.70 4-06 4.65 4.75 5.00
form, the transition starting with a pH of 8. Bearing in mind that dextran in alkaline medium may undergo oxidation [7], this transition may be due to the formation of new units with carboxyl groups. Indeed, our studies indicated that IR spectra of dextran and its copper complexes in alkaline medium contain absorption bands representing COOH groups. Bearing in mind these facts, further studies of complex formation of dextran with copper ions were carried out spectrophotometrically in the pH range of
Remtion
of dextran with
copper ions
489
D&ran does not oxidize under these conditions. Further, as indicated 6-8. previously, complexes are formed which absorb at &,,,=230 nm. It is also important to note that this pH range is interesting from a practical point of view. TABLE 2. RESULTS OF
DETERMINING
CONSTANTS
OF COMFLEX FOR-
MATION
-
-
-
D MxlO-*
PH
- 56
-
when
A=230
nm
1=0.45
cm
ax 104,
KxlO'a
mole/l.
-
6.50
0.65
5.41
7.6
6.65
1.10
9.26
14.0
6.70
9.25
12.0
10.50 11.67 12.17 12.42
13.3
7.10 7.25 7.50
1.12 1.26 1.40 1.46 1.49
6.60 6.80 6.90 7.10 7.45 7.80
0.63 0.82 1.05 1.22 1.50 1.58
4.14 6.41 8.20 9.53 11.72 12.34
6.45 6.65 6.80 7.00 7.05 7.25 7.75
0.56 om 1.10 1.33 1.35 1.47 1.59
4.37 6.87 8.62 10.39 10.54 11.48 12.42
6.80
8.9 9.4 15.6 11*5+2*7
43
3.1 2.7 3.1 2.0 1.9 2.0 2.5f0.6
25
-
6.8 6.2 5.6 5.0 4.3 3.5 4.2 5.1*1*1
L
Constants of complex formation were calculated by the Kuhn method. Absorption spectra were obtained under the same conditions, as described previously, however, copper concentration in solutions was reduced to 1.26 x X 10m3mole/l., which should ensure complete combination with dextran (Table 1). Dextran concentration was maintained at 1.62 g/dl which corresponds to O-1 base mole/l. Using our results and results derived from a study of copper-ammonium complexes of dextran [9] the reaction of dextran with copper ions may be decribed as R(OH),+CU”+P[CUR(O,H,-,,)I”-‘+RH+,
where R(OH), is the dextran unit.
(1)
V. N. TOLMACHEV et al.
a90
The equilibrium constant ,
,=[CuR(~,H,-~)l”-“[Hfln
’(2)
~~2+I13(OWJ
Since, according to experimental conditions [R (OH),]> [(X2+], using logarithm with formula (2) we obtain In - x l-x
=const+npH,
where 2 is the relative content of the complex and n-the number of protons isolated by the reaction. Figure 3 shows curves of equation (3), from which it can be seen that for all de&ran samples studied n N 2, i.e. on combining one copper ion two protons are most probably separated from one dextran unit. In this case CW+ : R(OH), = 1 : 1. Results of calculating constants R are shown in Table 2. It follows from A 3.6 -
al 5
I
7
I
‘9 FIG. 2
I
II
I
13 pH
7.8
, pH
FIU. 3
FIQ. 2. Relationship between the optical density of solutions and pH at A=230 nm; M x 10-a =66 (I), 43 (2) and 26 (3). FIU. 3. Determining the value of n. The ordinate axis shows the logarithmic ratio of combined copper ion concentrations to the product of free copper ion concentrations and the overall concentration of dextran log c,/(c,-c,)c~=A.
equation (1) that these constants incorporate constants of acid dissociation of hydroxyl groups of de&ran. K is practically independent of medium pH. For an unfractionated sample (M=56,000) this constant is somewhat higher than for fractionated samples, however, K showed no signikant relation to molecular weight. Tra7aslatedby E. SEB53SE
Dielectric relaxation of imido-epoxide polymers
1. 2. 3. 4. 5. 6. 7. 8. 9.
491
T. V. POLUSHINA, Dissertation, 1968 V. Ya. CEfERNYAK and T. V. POLUSHINA, Med. prom&’ 8: 39, 1961 F. KARUSH and M. SONENBERG, J. Amer. Chem. Sot. 71: 1369, 1949 T. A. SCOTT and E. II. MELIN, Analyt. Chem. 25: 1656, 1953 6. LEWIS and R. WILKINSON, Sovremennaya khimiya koordinatsionnykh soyedinenii (Modern Chemistry of Coordination Compounds). Izd. inostr. lit., 1963 K. ZAKREWSKY, J. KRYSIAK, K. MURAWSKY, Z. MAY and J. MALEC, Acta biochim. polon. 1: 27, 1954 J. BREMNER, J. S. 6. COX and G. F. MOSS, Carbohydrate Res. 11: 77, 1969 W. KUHN and J. TOTH, Z. Naturforsch. Al& 112, 1963 T. A. SCOTT, N. N. HELLMAN and F. R. SENTI, J. Amer. Chem. Sot. 79: 1178, 1967
DIELECTRIC RELAXATION OF IMIDO-EPOXIDE POLYMERS HARDENED WITH ACID ANHYDRIDES* YE. A. BABENKOVA, T. I. BO~SOVA, N. A. NIKONOROVA
and G. A. SHTRAIKEI~ Institute of High Molecular Weight Compounds, U.S.S.R. Academy of Sciences (Receiwed 15 October1973)
A study was made of dielectric relaxation of polyimidoepoxide polymers prepared from IES-1 oligomer and anhydride type curing agents. It was shown that mechanisms of dielectric polarization are similar to those in epoxide polymers. The addition of imide groups increases kinetic rigidity of the molecular network.
MODIFICATION of epoxy resins by addition of heterocyclic elements to the oligomer involves the preparation of polymers with increased heat resistance and satisfactory electric and mechanical properties. This paper examines the relaxation behaviour of hardened polyepoxides containing arimide groups (PIE) using the dielectric loss method. Polymers prepared using stoichiometric mixtures of an IES-1 imido-epoxide oligomer [I] and tetrahydrophthalic acid anhydride (THPA) or dianhydride of resorcin b&(3,4dicarboxyphenyl ester) (RDA) without accelerators as curing agents, were examined. IES-1 w&s obtained by a two stage method. The ilrst stage of the reaction involved the preparation of amidoacid by interaction of trimellitic acid anhydride and metaphenylene
*Vysokomol. soyed. A17: No. 2, 423-428,
1975.