Immobilization of Platinum(II) and Platinum(IV) Complexes on Oxidized Nanoporous Carbon Material and Evaluation of the Enthalpy of Adsorption

Article abstract of DOI:10.1134/S0036023618070136

Physicochemical study of cis-[Pt(NH3)2Cl2] and cis-[Pt(NH₃)₂Cl₂(OH)₂] is carried out, and immobilization of platinum complexes on the nanoporous carbon substrate is investigated. The solubility of cis-[Pt(NH₃)₂Cl₂] in 1 M HCl solution is determined, and the average enthalpy of dissolution is calculated: Δ_solH° = 27.3 ± 0.9 kJ/mol. The batch capacity is determined experimentally for cis-[Pt(NH3)2Cl2] and cis- [Pt(NH₃)₂Cl₂(OH)₂] to be 32.9 mg/g (0.17 mg-equiv/g) and 47.6 mg/g (0.24 mg-equiv/g), respectively. Immobilization of platinum complexes on the oxidized carbon surface is found to take place due to interaction between carboxy groups and ammine groups of platinum complexes. The resulting heat capacity curves are used to calculate the enthalpies of adsorption for cis-[Pt(NH₃)₂Cl₂] and cis-[Pt(NH₃)₂Cl₂(OH)₂] on the oxidized carbon surface, equal to 24.46 and 27.46 kJ/mol, respectively.

Full text of DOI:10.1134/S0036023618070136

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2018, Vol. 63, No. 7, pp. 923–929. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © L.M. Levchenko, N.I. Matskevich, V.E. Kerzhentseva, D.P. Pishchur, A.N. Mikheev, N.V. Gel’fond, I.V. Korol’kov, 2018, published in Zhurnal Neorganicheskoi
Khimii, 2018, Vol. 63, No. 7, pp. 880–887.
PHYSICAL METHODS
OF INVESTIGATION
Immobilization of Platinum(II) and Platinum(IV) Complexes
on Oxidized Nanoporous Carbon Material
and Evaluation of the Enthalpy of Adsorption
a,
a
a
a
L. M. Levchenko *, N. I. Matskevich , V. E. Kerzhentseva , D. P. Pishchur ,
a, b
a
a, b
A. N. Mikheev , N. V. Gel’fond , and I. V. Korol’kov
a
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
b
Novosibirsk National Research State University, Novosibirsk, 630090 Russia
*
e-mail: luda@niic.nsc.ru
Received February 22, 2017
Abstract⎯ Physicochemical study of cis-[Pt(NH ) Cl ] and cis-[Pt(NH ) Cl (OH) ] is carried out, and
3
2
2
3 2
2
2
immobilization of platinum complexes on the nanoporous carbon substrate is investigated. The solubility of
cis-[Pt(NH ) Cl ] in 1 M HCl solution is determined, and the average enthalpy of dissolution is calculated:
3
2
2
Δ H° = 27.3 ± 0.9 ꢀkJmol. The batch capacity is determined experimentally for cis-[Pt(NH ) Cl ] and cis-
sol
3 2
2
[
Pt(NH ) Cl (OH) ] to be 32.9 mgJg (0.17 mg-equivJg) and 47.6 mgJg (0.24 mg-equivJg), respectively.
3 2 2 2
Immobilization of platinum complexes on the oxidized carbon surface is found to taꢀe place due to interac-
tion between carboxy groups and ammine groups of platinum complexes. The resulting heat capacity curves
are used to calculate the enthalpies of adsorption for cis-[Pt(NH ) Cl ] and cis-[Pt(NH ) Cl (OH) ] on the
3
2
2
3 2
2
2
oxidized carbon surface, equal to 24.46 and 27.46 ꢀkJmol, respectively.
DOI: 10.1134JS0036023618070136
Platinum complexes are widely used in antitumor retaining the antitumor activity and reducing the
therapy. Once Rosenberg discovered the antitumor adverse effects.
activity of cis-[Pt(NH ) Cl ] bacꢀ in 1969, the era of
3
2
2
Sporadic studies have focused on treatment of
studying the carcinostatic activity of platinum deriva- oncologic diseases by targeted drug delivery; i.e., by
tives has started [1]. As a result of the research con- using nano- and micro-sized carriers [8].
ducted, cisplatin, the ꢀey component of the standard
chemotherapeutic drugs, has been brought into inter-
national practice [2–4]. Although platinum-based
drugs have a positive effect, their efficacy is still lim-
ited by adverse effects, such as nephrotoxicity and
neurotoxicity [5, 6], as well as innate or acquired resis-
tance of the organism. For this very reason, the search
for new antitumor drugs is currently ongoing and their
mechanisms of action are being studied [7].
In this connection, interest has arisen in studying
immobilization of platinum complexes on nanoporous
carbon substrate in order to design a container for
antitumor agent to reduce the administered concen-
trations of complexes and prevent their adverse effects,
as well as to modify the route of drug administration.
For oral drug administration, one needs to ꢀnow the
data on solubility of cis-[Pt(NH ) Cl ] in 1 M HCl
3
2
2
solution.
Therefore, it is necessary to obtain the data on sol-
ubility of cis-[Pt(NH ) Cl ] in 1 M HCl solution and
cis-[Pt(NH ) Cl ] is slowly and poorly soluble in
3
2
2
water and isotonic sodium chloride solution. Because
3 2
2
cis-[Pt(NH ) Cl ] is poorly soluble and has high tox- to determine the thermochemical parameters of interaction
3
2
2
between cis-[Pt(NH ) Cl ] or cis-[Pt(NH ) Cl (OH) ]
icity but is irreplaceable in clinical practice, research-
3 2
2
3 2
2
2
ers all over the world have been attempting to modify and oxidized nanoporous carbon material.
this complex chemically to reduce its toxicity and
We earlier investigated the physicochemical prop-
enhance solubility. An interesting method is to synthe- erties of oxidized nanoporous carbon materials and
size cis-[Pt(NH ) Cl (OH) ] by treating cis- showed that the nanoporous hydrophilic carbon
3
2
2
2
[
Pt(NH ) Cl ] suspension with 30% hydrogen perox- matrix can act as a good container; the immobilization
3 2 2
ide solution at 60–80°C followed by isolation of solid process is possible due to the interaction between oxy-
precipitate. This synthesis method does not alter the gen-containing functional groups on the carbon sur-
steric arrangement of chloro and amino groups, while face and H PtCl or H PtCl [9, 10].
2 4 2 6
923

9
24
LEVCHENKO et al.
tals was carried out on a Shimadzu XRD-7000 diffrac-
tometer (CuK radiation; Ni filter; 2θ range, 5°–60°;
α
scan step, 0.03°; exposure time 1 sJstep).
1
2
The samples for analysis were prepared using the
following procedure: polycrystals were triturated with
heptane in an agate mortar; the resulting suspension
was placed onto the polished side of a standard quartz
cell. After heptane had dried out, the sample was a thin
smooth layer of powder ~100 μm thicꢀ. Indexing of
the XRD patterns was performed using the data from
7
8
3
4
195
the PDF database [13]. The Pt NMR spectra of the
prepared solutions of platinum complexes in 1 M HCl
were recorded on an AVANCE 500 spectrometer at
5
6
1
07.27 MHz. The HPLC studies were conducted on a
Milichrom-A02 liquid chromatographic system
equipped with a standard UV detector (wavelength
range, 190–400 nm). The recrystallized cis-
[Pt(NH ) Cl ] complex was dissolved in deionized
3 2 2
water (electrical conductivity < 18 μS); a tenfold
excess of derivatizing agent (thiourea) was added, and
the solution was ꢀept at room temperature for 12 h.
The resulting solution was subjected to reversed-phase
chromatography (2 × 75 mm ProntoSIL C18; gradient
elution with 5–10% acetonitrile solution for 10 min;
flow rate, 150 μLJmin; column temperature, 38°C);
the signal was recorded at 250 and 300 nm.
Fig. 1. Solution calorimeter: (1) a brass lid, (2) a 0.25-L
Dewar vacuum vessel, (3) a brass container, (4) an
ampoule-breaꢀing device, (5) a refrigerator, (6) a stirrer,
(7) a heater, and (8) a platinum thermometer.
The enthalpy of dissolution of cis-[Pt(NH ) Cl ]
3
2
2
was determined calorimetrically. The measurements
were performed in an isothermal-jacꢀet calorimeter
The aim of this study was to investigate immobiliza-
(
Fig. 1); the jacꢀet temperature was maintained con-
tion of cis-[Pt(NH ) Cl ] and cis-[Pt(NH ) Cl (OH) ]
3
2
2
3 2
2
2
stant at 25°C. HCl (1 M) was used as a solvent.
on the oxidized carbon surface and to determine the
thermochemical parameters of interaction.
Temperature in the calorimeter was measured
using a platinum resistance thermometer. The calo-
rimeter was calibrated using potassium chloride to
maꢀe sure that it operates properly. The quantity of
heat absorbed upon dissolution of the compound in
the experiment was calculated using the formula (1):
EXPERIMENTAL
cis-[Pt(NH ) Cl ] was synthesized according to the
3
2
2
procedure described in [11]; cis-[Pt(NH ) Cl (OH) ]
3
2
2
2
Qexp = HΔTexp,
(1)
was synthesized by treating cis-[Pt(NH ) Cl ] with a
3
2
2
1
0% H O solution at 60°C [12].
2 2
where ΔT is the increase in temperature upon disso-
exp
lution; H is the thermal equivalent of the calorimeter
Individuality of compounds was proved by chemi-
cal analysis, high-performance liquid chromatography
calculated using the formula
195
(
HPLC); X-ray powder diffraction; Pt NMR, IR,
H = Qcal Tcal = UIt ΔTcal,
(2)
Raman, and UV spectroscopies; and thermal analysis.
Platinum content (wt %) in the complexes was deter-
mined gravimetrically; chlorine content, potentiomet-
rically. Nitrogen and hydrogen contents were deter-
mined on a Euro EA 3000 CHN analyzer. The elec-
tronic absorption spectra (EAS) were recorded on an
SF-102 spectrophotometer in the wavelength range of
where ΔT is the increase in temperature upon cali-
cal
bration; Q is the added quantity of heat (calibra-
cal
tion); I is the average current; U is the average voltage;
and t is the duration of load supply in the calibration
experiment.
Formula (3) is used to determine the quantity of
heat upon dissolution:
190–400 nm. The Fourier-transform IR spectra of the
synthesized platinum complexes and oxidized carbon
materials were measured on a SCIMITAR FTS 2000
Δ H = Q M m,
(3)
sol
exp
–1
where M is the molecular weight of the compound and
m is weight of the compound. The experimental pro-
cedure was described in detail in [14].
Fourier-IR spectrometer in the range of 375–4000 cm .
The samples for IR studies were prepared by pressing
KBr pellets. The Raman spectra were recorded on a
Triplemate Spex USA spectrometer by argon laser
In this study, we used oxidized nanoporous car-
excitation at 788 nm. X-ray phase analysis of polycrys- bon-modified sorbent (NCMS70–30) with specific sur-
RUSSIAN kOURNAL OF INORGANIC CHEMISTRY
Vol. 63
No. 7
2018

IMMOBILIZATION OF PLATINUM(II) AND PLATINUM(IV) COMPLEXES
925
2
face area of 330 m Jg, the number of carboxylic groups
being 3.5 ± 0.2% and the number of hydroxyl groups
being 1.17 ± 0.10% [15]. The enthalpy of dissolution
determined by us (17.41 ± 0.04 ꢀkJmol) coincided
with the literature value (17.42 ± 0.02 ꢀkJmol) [16].
3
3
2
3
1
4
cis-[Pt(NH ) Cl ] and cis-[Pt(NH ) Cl (OH) ]
3
2
2
3 2
2
2
were immobilized on NCMS7
as follows: 15 mL of
Pt
0–30
each solution, cis-[Pt(NH ) Cl ] (C = 607 mgJL) or
3
2
2
cis-[Pt(NH ) Cl (OH) ] (C = 584 mgJL), in 0.1 M
3
2
2
2
Pt
0
1
2
3
HCl was added to 100-mg NCMS
samples. The
0–30
7
Time, min
duration of sorption in the batch mode at room tem-
perature was 24 h. Next, the samples were filtered off
and dried to constant weight. The residual content of
platinum in the filtrates was determined by atomic
absorption spectroscopy on an ICE 3000 (Solaar)
spectrophotometer. The batch capacity was calculated
as follows: SC, mgJg = (C – C )15J1000 g.
Fig. 2. Chromatograms of cis-[Pt(NH3)2Cl2] and trans-
[
(
(
Pt(NH ) Cl ] solutions: (1) the underivatized complexes,
3 2 2
2) cis-[Pt(NH ) Cl ], (3) a derivatizing agent, and
3
2
2
4) trans-[Pt(NH ) Cl ].
3
2
2
in
eq
the initial moisture-containing samples, the tempera-
ture range of 280–370 K was used to evaluate the ther-
mal effects of interaction between the carbon material
and platinum compounds. The recorded heat capacity
curves were referred to 1 g of the sample under study.
The experimental data were processed using Origin 7.5
and Excel 2010 software.
The heat capacities of samples of cis-[Pt(NH ) Cl ],
3
2
2
cis-[Pt(NH ) Cl (OH) ], and NCMS carbon mate-
70–30
3
2
2
2
rials with platinum complexes were measured on a
NETZSCH DSC 204 F1 Phoenix differential scan-
ning calorimeter in the temperature range of 173–373 K.
The differential scanning calorimetric measurements
were conducted at a constant heating rate of 6 KJmin
in an open aluminum crucible in argon flow at a rate
of 25 mLJmin. Each sample weighed 10 mg; the Al O
RESULTS AND DISCUSSION
2
3
reference sample weighed 12.16 mg. The baseline sig-
nal recorded when heating two empty crucibles was
subtracted from the experimental results. The tem-
perature scale was calibrated using the results of melt-
ing the C H , C H , Hg, Ga, C H , C H COOH,
and In reference samples. Netzsch Proteus Analysis
software was used for calculating heat capacities and
for further averaging the results of three measure-
ments. In order to quantitatively assess the thermal
The cis-[Pt(NH ) Cl ] complex synthesized using
3
2
2
the procedure [11] may contain a trans-[Pt(NH ) Cl ]
3
2
2
impurity. Its content should not be higher than 0.5 wt %
according to the Pharmacopoeia no. 42-1790-88
February 17, 1988).
6
12
10 16
10
8
6
5
(
The chromatographic study of the solutions of
platinum complexes showed that cis-[Pt(NH ) Cl ]
3 2
2
and cis-[Pt(NH ) Cl (OH) ] were individual com-
3 2
2
2
effects, we outlined the boundaries of the region being pounds. The chromatograms of the solutions of plati-
analyzed and formed the baseline in it. Next, the peaꢀ num complexes are shown in Fig. 2: one can see that
of the thermal effect was formed with respect to this peaꢀ 1 corresponds to the mixture of platinum(II) iso-
baseline. We assume that the magnitude of thermal mers. The isomers were isolated by adding thiourea to
effect depends on the amount of compound (weighed the mixture. cis-[Pt(NH ) Cl ] was the first com-
3 2 2
sample) and thermal effect for a mixture of several pound eluted with the retention time of 1.1 min; the
compounds not reacting with each other is a sum of retention time of the second compound, trans-
thermal effects of the individual components. If the [Pt(NH ) Cl ], was 1.5 min. Table 1 lists the composi-
3
2
2
experimental curve differs from the overall thermo- tions and selected properties of cis-[Pt(NH ) Cl ] and
3
2
2
physical curve, it indicates that the components inter-
act with each other; the difference in thermal effects is
the enthalpy of interaction (reaction or sorption). As a
result, we plotted the calculated heat capacity curves
using the thermophysical curves of individual com-
cis-[Pt(NH ) Cl (OH) ].
3
2
2
2
Since the square-planar cis-[Pt(NH ) Cl ] com-
3
2
2
plex and the octahedral cis-Pt(NH ) Cl (OH) ] com-
3
2
2
2
plex belong to symmetry group C , the numbers of
2V
vibrational bands in the IR and Raman spectra will be
the same. Identical bands corresponding to stretching
vibrations ν(Pt–N) are observed in the IR and Raman
pounds (NCMS
, cis-[Pt(NH ) Cl ], and cis-
3 2 2
7
0–30
[
Pt(NH ) Cl (OH) ]) and their contents in the sam-
3 2 2 2
ples under study. By determining the difference
between the experimental and calculated curves, we
obtained the difference curves. Integration of the
–
1
spectra at 453 and 454 cm for cis-[Pt(NH ) Cl ] and
3 2
2
cis-[Pt(NH ) Cl (OH) ], respectively; similar bands
3 2
2
2
resulting thermophysical dependences yields the val- corresponding to the stretching vibration ν(Pt–Cl) are
–1
–1
ues of thermal effects. Since the thermal effects at observed at 323, 331 cm and 325, 343 cm , respec-
temperatures below 280 K are related to ice melting in tively. The stretching (symmetric and asymmetric)
RUSSIAN kOURNAL OF INORGANIC CHEMISTRY Vol. 63 No. 7 2018

9
26
LEVCHENKO et al.
Table 1. Composition and properties of cis-[Pt(NH ) Cl ] and cis-[Pt(NH ) Cl (OH) ]
3
2
2
3 2
2
2
195Pt NMR
M HCl
solution,
ppm
X-ray phase
analysis
PDF Number)
1
Complex
Pt, % N, % Cl, % Tdecomp
EAS
Solubility
(
cis-[Pt(NH ) Cl ]
64.82 9.33 23.00
315
310
220 nm
000-50-0643 –2125.856 0.25 wt %
[11]
3
2
2
3
01 nm
–1
(
ε = 140 L mol cm–1
cis-Pt(NH ) Cl (OH) ] 58.22 8.32 21.12
Fig. 7
010-84-0334
13]
–
0.30 wt %
[17]
3
2
2
2
[
and bending vibrations of the NH groups predomi- for the cis-[Pt(NH ) Cl (OH) ] complex because it is
3
3 2
2
2
nate in the IR spectra. The vibrations observed in the characterized by higher solubility and lower hydration
low-frequency region of the IR spectra are mostly the energy compared to those of cis-[Pt(NH ) Cl ] [23].
3
2
2
bending ones (Fig. 3). The absorption bands in the IR
and Raman spectra were ascribed according to the
procedure described in [17–22].
X-ray phase analysis of the oxidized carbon mate-
rial NCMS and platinum complexes adsorbed
7
0–30
onto it showed that the initial nanoporous oxidized
carbon material (NCMS ) has an amorphous
In order to investigate the immobilization of plati-
70–30
num complexes on the oxidized carbon surface, we structure (Fig. 4). Its XRD pattern contains the only
preliminarily measured the enthalpy of dissolution of lead reflection at 20°, while no reflections from plati-
the cis-[Pt(NH ) Cl ] complex in 1 M HCl at 50°C. num complexes are observed on the carbon surface.
3
2
2
The weight of each sample used for measurements was
We also analyzed the IR spectra of the initial
~
80 mg. Several parallel experimental runs were con- NCMS
, NCMS
+ cis-[Pt(NH ) Cl ], and
70–30 3 2 2
7
0–30
ducted; the average enthalpy of dissolution was Δ H° =
sol
NCMS
+ cis-[Pt(NH ) Cl (OH) ]. Vibrations of
3 2 2 2
70–30
2
7.3 ± 0.9 ꢀJꢁmol. Since the enthalpy of dissolution is
positive, it means that the process is endothermic
heat is absorbed during dissolution) and additional
energy is needed for cis-[Pt(NH ) Cl ] to be dissolved.
the carboxylic groups on the carbon surface, which are
–1
the strongest in the range of 500–2000 cm (Figs. 5
(
and 6), are observed in these samples at 1192 (1217,
–1
3
2
2
1
209) cm (bending vibrations of the COOH bond);
–1
the vibrations at 1579 (1566, 1560) cm can be
ascribed to asymmetric stretching vibrations of the
During immobilization, platinum complexes are
sorbed onto the oxidized carbon surface. The experi-
mentally determined batch capacity for cis-
–
ionized carboxylic group COO [24, 25].
[
Pt(NH ) Cl ] and cis-[Pt(NH ) Cl (OH) ] is 32.9 mgꢁg
Immobilization of platinum complexes on the oxi-
3
2
2
3 2
2
2
(
0.17 mg-equivꢁg) and 47.6 mgꢁg (0.24 mg-equivꢁg), dized carbon surface taꢀes place due to interaction
respectively. As expected, the sorption value is higher
584
5
44 494 453
1
251
197
323
1
188
112
537
2
2
454
237
3
273
331
557
10
20
30
40
50
60
600
500
400
300
200
100
2θ, deg
–1
Wavenumber, cm
Fig. 4. X-ray diffraction patterns of (1) cis-
Fig. 3. IR spectra of (1) cis-[Pt(NH ) Cl ] and (2) cis-
[Pt(NH ) Cl (OH) ] and (2) NCMS
+
cis-
3
2
2
3 2
2
2
70–30
.
–
1
Pt(NH ) Cl (OH) ] (2) at 100–600 cm
.
[Pt(NH ) Cl (OH) ]; and (3) NCMS
3
2
2
2
3 2
2
2
70–30
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY
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2018

IMMOBILIZATION OF PLATINUM(II) AND PLATINUM(IV) COMPLEXES
927
3
2
1
500
1000
1500
2000
2500
3000
3500
4000
4500
–
1
Wavenumber, cm
Fig. 5. IR spectra of (1) NCMS70–30, (2) NCMS70–30 + cis-[Pt(NH ) Cl ], and (3) NCMS
+ cis-[Pt(NH ) Cl (OH) ].
3 2 2 2
3 2
2
70–30
between carboxylic groups; the intensity of COOH are characterized by a ꢀinꢀ at ~270 K (0°C). This ꢀinꢀ
–
and COO vibrations decreases.
The Raman spectra of the NCMS
is probably related to ice melting in the samples under
study as they contained moisture. In the analyzed sam-
ples, water contains a certain amount of dissolved com-
pounds: a similar thermal effect was observed in [27].
, NCMS
cis-[Pt(NH ) Cl ], and NCMS +
70–30
+
7
0–30
70–30
cis-
3
2
2
[
Pt(NH ) Cl (OH) ] samples contain only two high-
3 2 2 2
–1
intensity broadened bands at 1338 and 1580 cm ; the
ratio between their intensities remains virtually the corresponding heat effects and to estimate the
unchanged upon the immobilization of platinum amount of moisture in the samples under study with
complexes. The band at 1580 cm in the Raman spec-
tra (the so-called G band or the E2 mode) corre-
sponds to symmetrical vibrations (ν ) of the sp –C–
Integration of the endotherms allows one to evaluate
–1
2
g
C , Jꢁ(g K)
p
2
s
5
4
3
2
sp –C– bonds from the C–C fragments of the planar
lattice that is typical of pure graphite [26]. The second
0.9
–1
band in the Raman spectra at 1338 cm (the so-called
D band or the A mode) is typical of the vibrations of
0.8
1g
3
3
3
tetrahedral carbon (sp –C–sp –C–, sp –C–X–
bonds). In the samples under study, vibrations of both
0.7
0.6
0.5
0.4
2
1
3
3
the sp –C–C– and sp –C–OH bonds contribute to
the D band, thus significantly broadening it. The
Raman spectra feature no vibrations typical of plati-
num complexes in the samples of oxidized carbon
material immobilized by platinum compounds, thus
being indicative of the superficial mechanism of bind-
ing of amino groups in platinum complexes to carbox-
ylic groups of the carbon surface that does not alter the
structure of carbon material.
200
250
300
350
T, K
Fig. 6. Temperature-dependent heat capacity in the sam-
ples: (1) cis-[Pt(NH ) Cl ], (2) cis-[Pt(NH ) Cl (OH) ],
In order to quantitatively evaluate the thermal
effect of interaction between platinum complexes and
the oxidized carbon surface, we recorded the heat capac-
ity curves in the temperature range of 170–370 K, which
3
2
2
3 2
2
2
(
3) sorbent NCMS
, (4) cis-[Pt(NH ) Cl ] adsorbed
0–30 3 2 2
7
onto NCMS
, and (5) cis-[Pt(NH ) Cl (OH) ]
70–30
3 2 2 2
adsorbed onto NCMS
7
0–30.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 63 No. 7 2018

9
28
LEVCHENKO et al.
Table 2. Assignment of absorption bands in the IR and Raman spectra of cis-complexes of platinum(II) and platinum(IV)
IR spectra
Raman spectra
ascription
of bands
ascription
of bands
[22]
cis-
cis-[Pt(NH3)2
cis-[Pt(NH ) Cl ]
cis-[Pt(NH ) Cl ]
3 2 2
3
2
2
[
Pt(NH ) Cl (OH) ]
Cl (OH) ]
3
2
2
2
2
2
[19–22]
3
286.3
205.4
3142
3050
νas(N–H)
νs(N–H)
δ(ΝH3)
3
1
625.0
541.7
295.8
1
1583.6
δas(HNH)
δ (NH )
1
s
3
1
379
δ ( NH )
1316
978
1375
s
3
1074
ρ (NH )
τ 3
796
ρ (NH ) (rocꢀing)
τ 3
5
57
ν(Pt–OH)
ν(Pt–O)
ν(Pt–N)
ν(Pt–Cl)
Bending vibrations
574
531
454
343
249
170
91
ν(Pt–OH)
ν(Pt–O)
ν(Pt–N)
ν(Pt–Cl)
5
44
532
454
331
273
237
527
453
325
259
160
4
3
53
23
251
197
188
112
Table 3. Temperatures corresponding to the features in heat capacity curves, thermal events, and estimated amounts of
water in samples of oxidized carbon material with platinum complexes immobilized thereon
Tinit
Tmax
Tfin
Water
content, %
No.
Compound, sample weight
ΔH, Jꢁg
K
1
2
3
4
cis-[Pt(NH ) Cl ], 5.64 mg
236
248
254
251
264
266
268
267
281
282
280
278
0.68
0.41
0.67
0.65
0.2
3
2
2
cis-[Pt(NH ) Cl (OH) ], 9.81 mg
0.12
0.2
3
2
2
2
NCMS70–30, 5.22 mg
NCMS70–30 + cis-[Pt(NH ) Cl ]
0.19
3 2
2
0.33 mgꢁg Pt
5
NCMS70–30 + cis-[Pt(NH ) Cl (OH) ]
247
268
280
1.08
0.32
3 2
2
2
0.48 mgꢁg Pt
Table 4. Heat values calculated per composition of the mix-
The heat effects listed in Table 4 were calculated for
the composition of the mixture where the content of
platinum salts was less than or equal to 10%. The
recorded heat capacity values were then referred to 1 g
of the sample under study and are shown in Table 5.
ture
ΔH
Sample
Jꢁg
Jꢁmol
The calculated thermal effect values support the
mechanism of physical adsorption, since this process
has low enthalpies of adsorption: from 8 to 34 ꢀJꢁmol.
Chemical adsorption is characterized by higher
enthalpies of chemisorption: from 40 to 120 ꢀJꢁmol.
NCMS70–30 + cis-[Pt(NH ) Cl ]
4.48
1344
2208
3 2
2
NCMS70–30 + cis-[Pt(NH ) Cl (OH) ] 6.61
3 2
2
2
allowance for the literature data for the enthalpy of fusion Hence, the enthalpies of adsorption of cis-Pt[(NH ) Cl
3
2
2
of ice (335 Jꢁg). The temperatures of thermal events and and cis-Pt[(NH ) Cl (OH) onto the oxidized carbon
3
2
2
2
water content are summarized in Tables 3 and 4.
surface (24.46 and 27.46 ꢀJꢁmol) agree with the data
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY
Vol. 63
No. 7
2018

IMMOBILIZATION OF PLATINUM(II) AND PLATINUM(IV) COMPLEXES
Table 5. Heat values calculated per gram of the sample
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929
ΔH
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(
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(
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and cis-[Pt(NH ) Cl (OH) ] complexes has been car-
3
2
2
2
13. Powder Diffraction File (ICDD, Pennsylvania, USA),
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release 2010.
14. N. I. Matsꢀevich, Th. Wolf, C. Greaves, and A. N. Bry-
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–
COO bonds decreases upon immobilization.
16. C. Gunter, R. Pfestorf, M. Rother, et al., Therm. Anal.
(
2) The solubility of cis-[Pt(NH ) Cl ] in 1 M HCl
3 2 2
Calorim. 33, 359 (1988).
solution has been determined for the first time, and
17. R. Faggiani, H. E. Howard-Locꢀ, and C. J. L. Locꢀ,
the average enthalpy of dissolution (Δ H° = 27.3 ±
.9 ꢀJꢁmol) has been calculated.
sol
Can. J. Chem. 60, 529 (1982).
0
1
8. N. N. Zheligovsꢀaya, RF Patent No. 2086261 (1997).
(
3) Batch capacity determined experimentally for
19. V. I. Kazbanov, A. K. Starꢀov, G. A. Kozhuꢀhovsꢀaya,
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and V. V. Neꢀlyudova, RF Patent No. 2292210 (2007).
3
2
2
cis-[Pt(NH ) Cl (OH) ], 47.6 mgꢁg (0.24 mg- 20. K. Naꢀamoto, Infrared and Raman Spectra of Inorganic
3
2
2
2
equivꢁg). The increase in batch capacity for the plati-
num(IV) complex is associated with higher solubility
of this complex.
and Coordination Compounds (Interscience, New Yorꢀ,
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, 61 (1961).
1
6
(
4) X-ray phase analysis of the adsorbed platinum
2
2
2
2
2. D. A. Panꢀratov, V. B. Soꢀolov, and Yu. M. Kiselev,
complexes onto oxidized carbon material NCMS
70–30
Zh. Neorg. Khim. 45, 1518 (2000).
has demonstrated that the initial oxidized nanoporous
carbon material has an amorphous structure; no
reflections of platinum complexes are observed on the
carbon surface, indicating that the resulting composite
is single-phase.
3. S. N. Ivanova, L. M. Gindin, and A. P. Chernyaeva,
Izvestiya Seꢀtora Aꢀad. Nauꢀ SSSR, No. 2, 3 (1974).
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complexes and the oxidized carbon surface has been 26. G. Dresselhaus and M. S. Dresselhaus, Light Scattering
evaluated quantitatively using the recorded heat
capacity curves. The enthalpies of adsorption for cis- 27. O. Yu. Eshevsꢀii, Vestn. Severn. (Arꢀt.) Fed. Univ.,
Ser.: Estestv. Nauꢀi, No. 2, 97 (2011).
in Solids III (Mir, Moscow, 1985) [in Russian].
Pt[(NH ) Cl and cis-Pt[(NH ) Cl (OH) onto oxi-
3
2
2
3 2
2
2
dized carbon surface are 22.46 and 27.46 ꢀJꢁmol,
respectively.
Translated by D. Terpilovskaya
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 63 No. 7 2018