Synthesis and thermal decomposition of [Bi6O6(OH) 2](NH2C6H4SO3) 4

Article abstract of DOI:10.1016/j.tca.2011.11.003

An investigation of the interaction of Bi(III) with an aqueous solution of sulfanilic acid at a higher temperature is performed. As a result, a new composition [Bi₆O₆(OH)₂](NH₂C ₆H₄SO₃)₄ is precipitated. This Bi(III) complex is characterized by various methods: elemental analysis, DTA, TG-MS, DSC, FTIR, and powder X-ray diffraction. Based on the experimental results, X-ray diffraction indexation as well as thermal decomposition products of the compound are suggested.

Full text of DOI:10.1016/j.tca.2011.11.003

Thermochimica Acta 528 (2012) 85–89
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Short communication
Synthesis and thermal decomposition of [Bi6O6(OH)2](NH2C6H4SO3)4
Alexander Zaharieva,∗, Nikolay Kaloyanovb, Christian Girginovc, Veneta Parvanovad
a Department of Chemistry, Technical University, 8, St. Kliment Ohridski blvd., 1000 Sofia, Bulgaria
b Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 8, St. Kliment Ohridski blvd., 1756 Sofia, Bulgaria
c Department of Physical Chemistry, University of Chemical Technology and Metallurgy, 8, St. Kliment Ohridski blvd., 1756 Sofia, Bulgaria
d Department of General and Inorganic Chemistry, University of Chemical Technology and Metallurgy, 8, St. Kliment Ohridski blvd., 1756 Sofia, Bulgaria
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 August 2011
Received in revised form 27 October 2011
Accepted 3 November 2011
Available online 12 November 2011
An investigation of the interaction of Bi(III) with an aqueous solution of sulfanilic acid at a higher tem-
perature is performed. As a result, a new composition [Bi6O6(OH)2](NH2C6H4SO3)4 is precipitated. This
Bi(III) complex is characterized by various methods: elemental analysis, DTA, TG–MS, DSC, FTIR, and pow-
der X-ray diffraction. Based on the experimental results, X-ray diffraction indexation as well as thermal
decomposition products of the compound are suggested.
© 2011 Elsevier B.V. All rights reserved.
Keywords:
Bi(III) complexes
Thermal decomposition
X-ray diffraction
DTA
TG–MS
DSC
1. Introduction
Nothing is found in the literature regarding the interaction
between Bi(III) and sulfanilic acid. On that account, investigat-
Bi(III) complexes with different ligands have found an increasing
implementation in medicine as main ingredient of mod-
ern antimicrobial and antitumour agents [1–3]. In most cases,
however, the synthesis of bismuth compounds with various inor-
ganic and organic anionic species in aqueous environment is
accompanied by significant hydrolysis of Bi(III) [3]. A series of insol-
ing this interaction and its resulting product could complement
the existing developments within the comparatively less explored
Bi(III) chemistry.
a
2. Experimental
uble compounds containing polycations with a general formula
(10−x)+
have been isolated, as x varies with pH of
[Bi6Ox(OH)8−x
]
The interaction of Bi(III) with sulfanilic acid was performed
as follows: 0.4 g Bi2O3 (Merck, 99.5%) were added to 1.0 dm3 1%
aqueous solution of HNH2C6H4SO3 (pH 2.7) (Merck, >98%). The
experimental conditions included 96 h of stirring at temperature
70 ◦C because of the low solubility of the acid. The white-yellowish
precipitate obtained was rinsed with hot double distilled water
until the outgoing water reached pH 7.0 to remove any acid resid-
uals. Afterwards, the product was dried in a desiccator over silica
gel.
The product’s composition was determined by elemental anal-
ysis on VarioELV5.18.018 (Elementar Analysensysteme GmbH,
Hannau, Germany) performing in CHNS mode.
Infrared spectra were recorded on Varian 660-IR FTIR Spectrom-
eter within 4000–450 cm−1, in KBr pellets, and in terms of the water
vibrations–in Nujol suspension rather than in KBr.
the solution [4,5]. Within pH 2.7–3.5 a species having composition
[Bi6O6(OH)2]4+ has been formulated [6,7].
Recently, a number of novel Bi(III) complexes with organic and
inorganic ligands have been demonstrated. The tartaric- [8–10],
citric- [11,12] as well as oxalic acid [13–15] complexes have been
a subject of a thorough investigation. Other complexes contain-
ing anions of gallic, malonic, lactic, nitrilotriacetic and sulfamic
acids have been reported [16–18]. Synthesis of various Bi(III)-
oxidohydroxidocarboxylates has been performed as well [19].
Currently, some of the newest routes of synthesizing Bi(III) com-
pounds appear to be the development of coordination oxoclusters
[20], as well as the development of different mixed oxide systems
[21,22].
Powder X-ray diffraction (XRD) patterns were collected within
the range of 3–77◦ 2ꢀ with a constant step of 0.02◦ 2ꢀ on Bruker D8
Advance diffractometer with Cu K␣ radiation and LynxEye detector.
∗
Corresponding author. Tel.: +359 884761912.
E-mail address: alexs zahariev@yahoo.com (A. Zahariev).
0040-6031/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.tca.2011.11.003

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A. Zahariev et al. / Thermochimica Acta 528 (2012) 85–89
Table 1
FTIR spectral data and band assignments of [Bi6O6(OH)2](NH2C6H4SO3)4.
FTIR (cm−1
)
Assignment
3535
3448
3353
3050
1627
ꢂOH (shoulder)
ꢂasNH2
ꢂsNH2
ꢂC–H (from Ar)
ıscisNH2
1599–1430
1300
1180
1124
1026
829
ꢂC C (from Ar)
ꢂN–C
ꢂasSO2
ıBi–OH
ꢂsSO2
ꢃC–H p-disubstituted Ar (out of plane bending)
698
565
469
ıwN–H
ꢂBi–O
ıBi–O
recognized at 1124 cm−1 (␦Bi–OH) [30], at 1627 cm−1 (ıscisNH2) as
well as at 698 cm−1 (ıwN–H). At 565 cm−1 and 469 cm−1 two bands
appear, corresponding to ꢂBi–O and ıBi–O, respectively [25]. In
Table 1 the values of vibrations and their corresponding functional
groups are presented.
Based on the data from the elemental analysis and FTIR
spectrum, the following stoichiometric composition of the Bi(III)-
complex could be ascertained: [Bi6O6(OH)2](NH2C6H4SO3)4. This
composition represents also the ratio 3:2 between Bi-sulfanilic acid
anion.
Fig. 1. FTIR spectrum of [Bi6O6(OH)2](NH2C6H4SO3)4.
The data were evaluated by the Diffracplus EVA and Topas 4.2.
packages.
DTA-TG measurements were performed on LABSYSTM evo
(SETARAM) within 20–1000 ◦C and 10 ◦C min−1 rate in Ar atmo-
sphere by flow rate 20 cm3 min−1. A thermostated balance that uses
the technique of a beam articulated around a torsion band is in
operation. The sample mass used was 25.0 mg; the weighing pre-
cision is 0.01%. Empty alumina crucible was used as a reference
sample. Gas analyzer OmniStarTM by Pfeiffer Vacuum was used to
determine the qualitative composition of gases released.
Also, a DSC analysis was performed on a scanning calorimeter
Stanton Redcroft (England) within 0–650 ◦C and a heating rate of
5 ◦C min−1. Sample mass used was 6.0 mg taking Pt crucible and
the latter is used empty as a reference. Inert (Ar) atmosphere was
ensured during the DSC measurements.
In Fig. 2 the XRD pattern of the newly prepared complex is pre-
sented. Within this figure no one of the known Bi(III)-containing
phases is found. Therefore, the diffraction pattern is indexed
within the tetragonal I4 space group with unit cell parameters
˚
˚
a = 26.5122 A and c = 5.7613 A. X-ray diffraction data of the initial
compound after indexation are presented in Table 2.
The thermal decomposition of [Bi6O6(OH)2](NH2C6H4SO3)4 is
studied by DTA and TG-analyses (Fig. 3) coupled with mass-
spectrometry, differential scanning calorimetry (Fig. 4), X-ray
diffraction (Fig. 5), and FTIR spectrometry (Fig. 6).
A large endothermic effect is observed in DTA-curve (Fig. 3) in
the temperature range of 360–520 ◦C with Tmax = 415 ◦C, while in
DSC-curve (Fig. 4) two endothermic effects appear within the same
range.
The first endothermic effect in DSC is split into two peaks with
Tmax = 411.6 ◦C and Tmax = 419.7 ◦C, respectively. The second one is
considerably weaker and is observed at Tmax = 452.9 ◦C. The differ-
ence found in the tracks of DTA and DSC curves could be explained
by the higher resolution of the DSC method. From 360 ◦C to 520 ◦C
The endothermic peaks visible within DTA and DSC curves and
the corresponding mass loss (ꢁm) of the samples were analyzed.
On this basis, the temperature ranges were defined within which
an additional isothermal heating of the compound synthesized was
carried out. Samples were heated in consecutive 10 ◦C steps in the
360–520 ◦C range until reaching a constant sample mass, followed
by a calculation of the mass decrease (ꢁm, %) of each sample.
Two temperatures (410 ◦C and 500 ◦C) were selected. They cor-
respond to the samples whose ꢁm coincides with ꢁm from TG
curve. The mass change according to TG curve was measured up
to its track change. The mass (m) of each initial sample was 1.0 g
and was heated for 2 h. After heating, the samples were cooled out
(25 ◦C) and kept in a dessicator over silica gel. Their composition
was identified by FTIR and powder XRD analyses.
3. Results and discussion
The data from the elemental analysis of the complex synthesized
indicated by the symbols of the elements are presented below and
are within 0.40% of the theoretical values.
Calcd.% : N − 2.70; C − 13.89; S − 6.18; H − 1.25
Found% : N − 2.68; C − 13.56; S − 6.00; H − 0.92.
In Fig. 1 FTIR spectrum of the syn−thesized compound is presented.
From this figure the bands of SO3 group, characteristic vibrations
of 4-disubstituted aromatic ring as well as those of the amino group
[23,24], are identified. Within the range 3600–3100 cm−1, an over-
lap of the stretching vibrations of OH with those of the amino group
is visible. Also, the bending vibrations of both functions could be
Fig. 2. XRD pattern of [Bi6O6(OH)2](NH2C6H4SO3)4.

A. Zahariev et al. / Thermochimica Acta 528 (2012) 85–89
87
Table 2
X-ray diffraction data from indexing the [Bi6O6(OH)2](NH2C6H4SO3)4.
2ꢀ (◦)
dexp (Å)
I (%)
100
h k l
dcalc (Å)
4.72
6.66
18.7456
13.2596
8.3278
6.2366
5.9203
5.1746
4.5291
4.2876
3.8926
3.7359
3.3564
3.2535
3.0747
2.9224
2.8540
2.7269
2.6450
2.5950
2.3969
2.2821
2.0569
1.9275
1.8641
1.7593
1.6728
1.6290
1.5665
1 1 0
0 2 0
1 3 0, 3 1 0
3 3 0
4 2 0, 2 4 0
1 2 1, 211
3 2 1, 231
1 4 1, 4 1 1
0 5 1, 3 4 1, 4 3 1
2 5 1, 5 2 1
5 4 1, 4 5 1
6 3 1, 3 6 1
2 7 1, 7 2 1
5 6 1, 6 5 1
1 8 1, 8 1 1, 4 7 1, 7 4 1
1 3 2, 3 1 2
18.7469
13.2561
8.3888
6.2490
5.9283
5.1819
4.5351
4.2909
3.9015
3.7428
3.3623
3.2591
3.0783
2.9246
2.8560
2.7243
2.6419
2.5997
2.3986
2.2843
2.0566
1.9299
1.8646
1.7574
1.6715
1.6295
1.5672
16
1
2
2
1
2
1
2
1
9
3
1
8
4
1
2
2
1
1
2
1
2
1
1
1
1
10.58
14.19
14.94
17.09
19.61
20.75
22.83
23.77
26.51
27.37
28.99
30.55
31.33
32.78
33.81
34.51
37.49
39.38
44.17
47.08
48.80
51.89
54.84
56.56
58.92
0 4 2
10 2 0, 2 10 0
11 0 1, 1 0 11
7 1 2, 5 5 2, 1 7 2
12 1 1, 9 8 1, 8 9 1, 1 12 1
2 10 2, 10 2 2
10 9 1, 9 10 1
1 6 3, 6 1 3
6 5 3, 5 6 3
12 6 2, 6 12 2
16 3 1, 3 16 1, 12 11 1, 11 12 1
Fig. 4. DSC curve of [Bi6O6(OH)2](NH2C6H4SO3)4.
The XRD pattern of this sample (Fig. 5a) represents the following
composition: ␣-Bi2O3 [26], Bi14O20SO4 [27], Bi [28] and an amor-
phous organic-containing phase. The presence of metallic Bi can
be explained taking into consideration the strong reductive action
of NH3, NO, and CO, derived after the decomposition. In the FTIR
spectrum of the sample heated at 410 ◦C (Fig. 6a) the characteris-
tic absorption bands of the functional groups of the phases found
in XRD are observed. A broad band at 1116 cm−1 is assigned to
the stretching vibrations ꢂSO2 from SO4 groups [23,24]. Within
620–480 cm−1, ıSO2 and ꢂBi–O overlap [25,29]. Moreover, in this
the TG-curve changes twice its character (Fig. 3). From experimen-
tal data obtained by DTA, TG, and DSC, it can be concluded that
in the temperature range under consideration the thermal decom-
position of [Bi6O6(OH)2](NH2C6H4SO3)4 occurs in two stages. For
confirmation of this statement, an isothermal heating (410 ◦C and
500 ◦C) of the initial compound’s samples is performed.
Mass loss ꢁm = 16.8% calculated from thermogravimetric data
within 360–430 ◦C corresponds to the first endothermic peak
(Fig. 3). During the process related to this effect, a simultane-
ous release of NH3, NO, CO, and CO2 is registered as a result
of aromatic ring decomposition. The qualitative composition of
these gases is established after mass-spectrometric measurements.
Furthermore, for this first endothermic effect, enthalpy change
ꢁH0 = 290.5 1.0 kJ mol−1 is calculated using the DSC data. A very
good coincidence between mass loss (ꢁm = 17.0%) of the sample
heated at 410 ◦C and ꢁm derived from the TG-curve is observed.
spectrum the stretching vibration of OH appears at 3431 cm−1
,
and in the range of 1034–1186 cm−1 ıOH overlaps with ꢂSO2 [30].
There are several bands that belong to groups involved in the
Fig. 5. XRD patterns for solid residuals after isothermal heating at two tempera-
tures: (a) 410 ◦C; (b) 500 ◦C. The phases are denoted as follows: , Bi28O32(SO4)10
;
Fig. 3. TG-DTA curves of [Bi6O6(OH)2](NH2C6H4SO3)4.
ꢀ, Bi14O20SO4; ᭹, Bi; , Bi2O3.

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A. Zahariev et al. / Thermochimica Acta 528 (2012) 85–89
During the first stage, the thermal decomposition of
[Bi6O6(OH)2](NH2C6H4SO3)4 is released in the temperature
range 360–430 ◦C. At this stage, the decomposition of the aromatic
ring proceeds along with simultaneous evolution of NH3, NO, CO
and CO2 and the following phases are formed: ˛-Bi2O3, Bi14O20SO4,
Bi, and amorphous organic-containing phase.
The second stage lies within 430–520 ◦C. At this stage CO2 and
H2O are released, and after the decomposition of amorphous phase,
the Bi28O32(SO4)10 oxosulfate is formed along with the crystalline
phases of the first stage.
4. Conclusions
A
complex
of
Bi(III)
with
a
composition
[Bi6O6(OH)2](NH2C6H4SO3)4 is synthesized on the basis of
Bi2O3 and NH2C6H4SO3H, and the conditions of synthesis are
defined. The composition is confirmed by elemental analysis
and FTIR spectroscopy. Using X-ray diffraction, the symmetry
(tetragonal; space group I4) and the unit cell parameters are
determined. By means of DTA-TG and DSC analyses, the thermal
behaviour of the initial complex is studied. Two stages of thermal
decomposition are established along with the composition of the
gas phases evolved. Thereafter, the phase composition of the solid
residuals derived at both heating stages is resolved by FTIR and
XRD.
Fig. 6. FTIR spectra of isothermal heating products: (a) 410 ◦C; (b) 500 ◦C.
organic-containing amorphous phase, namely at 1706 cm−1 for
ꢂC O and at 2929 cm−1 for ꢂasCH3 and/or ꢂasCH2 moieties. The
absence of bands for ꢂC–H (3050 cm−1) and ꢃC–H (829 cm−1), as
well as bands responding to ꢂC C (within 1599–1430 cm−1), con-
firms the decomposition of the aromatic ring. It is worth saying that
in the FTIR spectrum considered (Fig. 6a) the characteristic bands
of ꢂasNH2 and ꢂsNH2 are absent. This is an evidence of the complete
transformation of the amino group into NH3 and NO.
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