Synthesis and characterization of Azo schiff bases and their β-lactam derivatives

Article abstract of DOI:10.14233/ajchem.2020.22657

Azo salicylaldehyde (I5) was synthesized by reaction of 5-bromo-salicylaldehyde with diazonium salt of 4-nitroaniline by diazotization method. Thus, synthesized azoaldehyde was treated with variable 2-aminobenzothiazoles (I6a-f) to synthesize the Schiff bases (I7a-f). The β-lactam derivatives (I8a-f) were also synthesized. All the newly synthesized compounds were characterized by TLC, UV-visible and FT-IR techniques.

Full text of DOI:10.14233/ajchem.2020.22657

Asian Journal of Chemistry; Vol. 32, No. 6 (2020), 1520-1524
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2020.22657
Synthesis and Characterization of Azo Schiff Bases and their β-Lactam Derivatives
*
ANIL H. SHINDE and C.J. PATIL
Organic Research Laboratory, Department of Chemistry, Smt. G.G. Khadse College, Muktainagar-425306, India
*Corresponding author: E-mail: drcjpatil@yahoo.com
Received: 29 January 2020;
Accepted: 18 April 2020;
Published online: 30 May 2020;
AJC-19907
Azo salicylaldehyde (I5) was synthesized by reaction of 5-bromo-salicylaldehyde with diazonium salt of 4-nitroaniline by diazotization
method. Thus, synthesized azoaldehyde was treated with variable 2-aminobenzothiazoles (I6a-f) to synthesize the Schiff bases (I7a-f).
The β-lactam derivatives (I8a-f) were also synthesized.All the newly synthesized compounds were characterized by TLC, UV-visible and
FT-IR techniques.
Keywords: Azo salicylaldehyde, Schiff base, 2-Amino-benzothiozole, β-Lactam.
synthesized by the cyclization of imines and resulted in the
formation of 3-carbon and 1-nitrogen ring (β-lactam ring),
which is highly reactive [2]. In this present investigation work,
we are interested in the combination of azo group with the
Schiff base fragment, using 2-aminobenzothiazoles and then
further converted the azo Schiff base into β-lactam derivatives.
INTRODUCTION
Schiff bases and their β-lactam derivatives exhibited a
variety of applications in clinical, biological, analytical and
pharmacological activities [1-5]. The Schiff bases (-CH=N-)
playes an important function as an organic synthone for newer
molecules. In addition, moieties within the azole class have
been of great scientific exploitation and interest as these are
accompanied with almost all the biological profiles and the
pharmacological activities [6-8]. Similarly, the β-lactam ring
is part of the core structural feature in an array of drug cate-
gories and are active against a wide range of microorganisms
[9-11].
In addition, the antimicrobial activity of aldimines and
ketimines containing electron-attracting and electron-repelling
groups are widely used for industrial purposes and also exhibit
a broad range of biological activities [12]. These imines are in
a forms of syn- or anti-oxime and phenolic or amino Schiff bases.
The synthesis of compounds containing chloro group or azo
moiety exhibit the herbicidal activities [13,14]. The azo group
in addition to the other groups in the same compounds exhibit
important biological activities like antibacterial, antioxidant
and other pharmacological activities [15-18].
EXPERIMENTAL
All the reagents were of synthesis grade and purchased
from Sigma-Aldrich, USA. The progress of reaction was moni-
tored by TLC. TLC plates were of silica gel coated aluminum
plates made by Merck. Physical constants recorded on Equip-
tronics digital m.p./b.p. apparatus in degree calculus on model
EQ-730. The UV-Vis spectra were recorded on Shimadzu UV
1800 series spectrophotometer in the range of wavelength 800-
200 nm. FT-IR spectra were recorded on Shimadzu FT-IR
spectrometer using KBr pellets in the range of 4000-400 cm-1.
1H NMR was recorded with delta NMR software (Jeol) in
CDCl3 as solvent and TMS as internal standard. The chemical
shifts are reported in ppm (δ) downfield from TMS.
Synthesis of azo salicylaldehyde (I5): In 100 mL beaker
charged 5.13 g (0.0372 mol) 4-nitroaniline, added 25 mL conc.
HCl and 20 mL distilled water. Cooled the solution to 0 ºC by
in ice bath (solution A). In a hard glass tube, charged 3.105 g
(0.045 mol) sodium nitrite and dissolved in 15 mL water and
cooled the solution to 0 ºC in ice bath (solution B).
Azo unit linked with Schiff bases exhibited a diverse appli-
cations in chemical as well as pharmacological activities [19-
22]. The β-lactams are one of the most commonly prescribed
drug classes with numerous clinical indications generally
This is an open access journal, and articles are distributed under the terms of the Attribution 4.0 International (CC BY 4.0) License. This
license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit the author for the original
creation. You must give appropriate credit, provide a link to the license, and indicate if changes were made.

Vol. 32, No. 6 (2020)
Synthesis and Characterization of Azo Schiff Bases and their β-Lactam Derivatives 1521
When both the solutions attained 0 ºC temperature, solution
B was added dropwise in solution A with constant stirring.
During addition, temperature of the reaction solution should
be maintained below 10 ºC. A pinch of urea was added in order
to decompose the excess nitrous acid and filtered the solution.
5-Bromo salicylaldehyde (7.477 g, 0.0372 mol) was added
in 35 mL 10 % NaOH solution and stirred till clear solution
obained. The solution was cooled to 0 ºC and then added the
filtrate slowly to this content with constant stirring. After
complete addition, allowed the solution to stand for 10 min in
ice bath. Filtered the light orange dye, washed with cold water,
recrystallized and stored in an air tight container [16]. Yield:
61.49 %, m.p.: 106-108 ºC, Rf: 0.33. Elemental analysis calcd.
(found) % of C13H8N3O4Br: C: 44.57 (43.12), H: 2.28 (2.23),
N: 12.00 (11.52). IR (KBr, νmax, cm-1): 3225 (-OH str.), 3075
(C-H arom.), 2850 (-CHO), 1605 (C=O), 1521 (C=C arom.),
1520, 1350 (-NO2), 1305, 1463 (N=N), 1305 (-CH), 535 (C-
Br). UV analysis: 337 and 236 nm.
thermometer pocket. To this, added 70 mL toluene and attached
Dean and Stark apparatus properly. Few drops of acetic acid
was added and allowed to reflux for 4 h and monitored the
reaction with TLC. The solvent was removed under reduced
pressure after the completion of the reaction. The solid product
obtained was washed with ethanol and recrystallized by
hot water (Scheme-I). The physico-analytical data is given in
Table-1.
Synthesis of β-lactam derivatives (I8a-f): In 100 mL
round bottom flask containing reflux condenser and thermo-
meter pocket in a ice-bath, a mixture of 0.00125 mol of Schiff
base (I7a-f) and 0.15 mL TEA was dissolved in 20 mL 1,4-
dioxane was stirred for 0.5 h. To this cold solution, 0.15 mL
(0.00186 mol) chloroacetyl chloride was added slowly added
at > 5 ºC. Refluxed the contents for 12-15 h and TLC was
checked after 9, 11 and 13 h. After clear TLC, 1,4-dioxane
was distilled off and a viscous liquid as the resultant content
was obtained. It was washed with 10% NaHCO3 to remove
unreacted chloroacetyl chloride, finally washed with cold water
and recrystallized by methanol (Scheme-II). The physico-
analytical data is given in Table-2.
Synthesis of Schiff base (I7a-f): Equimolar proportion
of compound I5 and relevant benzothiazole (I6a-f) was mixed
in 250 mL round bottom flask fitted with water condenser and
N2.HCl
H
O
H
O
NH2
Br2
OH
OH
NaNO2
HCl
gl. Acetic acid
Br
NO2
I2
NO2
I1
I4
R1
I3
N
S
H
N
R1-
S
N
H
O
HO
a
NH2
= -H
b = 6-Cl-4-NO2-
c = 6-F-
OH
Br
R1
I6a-f
d = 4,6-F2-
N
N
e = 4-CH3-6-NO2-
Br
N
N
Solvent
f
= 6-NO2-
I5
NO2
NO2
I7a-f
Scheme-I: Synthesis of azo Schiff bases
TABLE-1
PHYSICO-ANALYTICAL DATA OF SYNTHESIZED AZO SCHIFF BASES (I7a-f
)
Elemental analysis (%): Calcd. (found)
Yield (%)
(Rf value)
m.f.
m.w., g/mol)
Colour
(m.p., °C)
Compd.
-R1
-H
(
C
H
N
C20H12N5O3SBr
(482)
C20H10N6O5SBrCl
(561.5)
C20H11N5O3SBrF
(500)
C20H10N5O3SBrF2
(518)
C21H13N6O5SBr
(541)
C20H11N6O5SBr
(527)
Light brown
(109-111)
Yellow
(102-104)
Light yellow
(170-172)
Light brown
(106-108)
Yellow
I7a
I7b
I7c
I7d
I7e
I7f
90.27 (0.40)
86.90 (0.44)
87.70 (0.43)
76.03 (0.50)
85.92 (0.47)
70.55 (0.46)
49.79 (48.54)
42.74 (41.53)
48.00 (47.65)
46.33 (45.63)
46.58 (45.65)
45.54 (44.68)
2.49 (2.75)
14.52 (14.20)
14.96 (13.68)
14.00 (13.75)
13.59 (13.26)
15.53 (15.25)
15.94 (15.85)
6-Cl, 4-NO2
6-F
1.78 (1.63)
2.2 (2.15)
4,6-F2
1.93 (1.86)
2.40 (2.38)
2.08 (1.98)
4-CH3, 6-NO2
6-NO2
(91-93)
Light brown
(94-96)

1522 Shinde et al.
Asian J. Chem.
R1
N
S
H
N
HO
R1
NO
N
2
HO
O
N
S
N
Cl
N
Cl
Br
Br
N
O
Cl
N
R1-
I8a-f
a = -H
b = 6-Cl-4-NO2-
c
= 6-F-
d = 4,6-F2-
e
f
= 4-CH3-6-NO2-
= 6-NO2-
NO
2
I7a-
f
Scheme-II: Synthesis of β-lactam derivatives
TABLE-2
PHYSICO-ANALYTICAL DATA OF SYNTHESIZED β-LACTAM DERIVATIVES (I8a-f
)
Elemental analysis (%): Calcd. (found)
Yield (%)
(Rf value)
m.f.
m.w., g/mol)
Colour
(m.p., °C)
Compd.
-R1
-H
(
C
H
N
C22H13N5O4SBrCl
(558.5)
C22H11N6O6S BrCl2
(639)
C22H12N5O4SBrClF
(576.5)
C22H11N5O4SBrClF2
(594.5)
C23H14N6O6SBrCl
(617.5)
C22H12N6O6SBrCl
(603.5)
Brown
(267-269)
Dark brown
(72-74)
Dark brown
(60-62)
Light brown
(242-244)
Brown
I8a
I8b
I8c
I8d
I8e
I8f
78.26 (0.49)
81.53 (0.50)
77.94 (0.58)
74.39 (0.55)
83.33 (0.57)
80.79 (0.51)
47.27 (46.59)
41.40 (40.89)
45.81 (44.56)
44.43 (43.95)
44.73 (44.12)
43.74 (43.02)
2.34 (2.30)
12.53 (12.45)
6-Cl, 4-NO2
6-F
1.74 (1.71)
2.10 (2.05)
1.86 (1.79)
2.27 (2.15)
1.99 (1.91)
13.17 (13.11)
12.14 (11.95)
11.77 (11.44)
13.61 (13.21)
13.92 (13.87)
4,6-F2
4-CH3, 6-NO2
6-NO2
(205-207)
Light brown
(73-75)
indicates the stretching vibration of -OH group.A band at 3075
cm-1 was due to aromatic -C-H bond stretching vibration and
frequency at 2850 cm-1 was due to -C-H stretching of aldehyde
group. Moreover, bands at 1520 and 1350 cm-1 indicated the
stretching vibration of -NO2 group. The lower IR band at 535
cm-1 was due to stretching vibration of C-Br group.
Similarly, azo Schiff base and β-lactam derivatives were
synthesized and characterized successfully (Table-3). The β-
lactam ring was occurred by the reaction of Schiff bases with
chloroacetyl chloride in dioxane solvent and in IR spectrum
the carbonyl group was seen between 1710 and 1730 cm-1.
RESULTS AND DISCUSSION
In the present work, p-nitrophenyldiazonium chloride
reacted with 5-bromo salicylaldehyde to obtain azo salicylal-
dehyde and then to get relevant azo-schiff bases by reacting
azo salicylaldehyde with substituted 2-aminobenzothiazoles
as shown in Scheme-I.
The UV-vis spectrum in ethanol for compound I5 shows
two bands at 337 and 236 nm which are attributed due to n→π*
and π→π* transition, respectively. The characteristic stretching
frequencies of compound I5 exhibited the band at 3225 cm-1
TABLE-3
UV AND FT-IR SPECTRAL DATA OF AZO SCHIFF BASES (I7a-f) AND β-LACTAMS DERIVATIVES (I8a-f)
FT-IR (νmax, cm-1)
Compd.
IUPAC name
λmax (nm)
2-(Benzothiazol-2-yliminomethyl)-4-bromo-6-(4-nitro- 220, 279, 3365 (C-OH), 3076 (C-H arom.), 1662 (C=N), 1550 (C=C
I7a
phenylazo)-phenol
344
arom.), 1454 (N=N), 1342 (NO2), 1091 (C-O), 806 (C-S), 547
(C-Br)
4-Bromo-2-[(6-chloro-4-nitro-benzothiazol-2-
ylimino)-methyl]-6-(4-nitro-phenylazo)-phenol
223, 374 3468 (C-OH), 3089 (C-H arom.), 1654 (C=N), 1531 (N=N),
1460 (C=C arom.), 1091 (C-O), 815 (C-S), 1350, 1342 (C-NO2),
887 (C-Cl), 443 (C-Br)
I7b

Vol. 32, No. 6 (2020)
Synthesis and Characterization of Azo Schiff Bases and their β-Lactam Derivatives 1523
4-Bromo-2-[(6-fluoro-benzothiazol-2-ylimino)-
methyl]-6-(4-nitro-phenylazo)-phenol
249, 353 3383 (C-OH), 2964 (C-H arom.), 1616 (C=N), 1480 (C=C
arom.), 1512 (N=N), 1456, 1342 (C-NO2), 1099 (C-F), 812 (C-
S), 524 (C-Br)
I7c
4-Bromo-2-[(4,6-difluoro-benzothiazol-2-ylimino)-
methyl]-6-(4-nitro-phenylazo)-phenol
4-Bromo-2-[(4-methyl-6-nitro-benzothiazol-2-
ylimino)-methyl]-6-(4-nitro-phenylazo)-phenol
205, 234, 3230 (C-OH), 2954 (C-H arom.), 1672 (C=N), 1502 (N=N),
I7d
I7e
371
1470 (), 1450, 1342 (C-NO2), 1096 (C-F), 510 (C-Br), 821 (C-S)
231, 252, 3483 (C-OH), 3100 (C-H arom.), 2962 (C-H alkyl), 1662 (C=N),
340
1517 (N=N), 1490 (C=C arom.), 1483, 1342 (C-NO2), 887 (C-
Cl), 806 (C-S), 525 (C-Br)
4-Bromo-2-[(6-nitro-benzothiazol-2-ylimino)-methyl]- 229, 247, 3531 (C-OH), 2964 (C-H arom.), 1656 (C=N), 1590 (C=C
6-(4-nitro-phenylazo)-phenol 345 arom.), 1514 (N=N), 1342 (C-NO2), 806 (C-S), 464 (C-Br)
1-Benzothiazol-2-yl-4-[5-bromo-2-hydroxy-3-(4-nitro- 220, 277, 3373 (C-OH), 2920 (C-H alkyl), 1589 (C=N), 1522 (), 1444
phenylazo)-phenyl]-3-chloro-azetidin-2-one 371 (N=N), 1304 (C-NO2), 807 (C-Cl), 765 (C-S), 550 (C-Br)
4-[5-Bromo-2-hydroxy-3-(4-nitro-phenylazo)-phenyl]- 238, 399 3468 (C-OH), 2920 (C-H alkyl), 1628 (C=N), 1500 (C-NO2),
I7f
I8a
I8b
3-chloro-1-(6-chloro-4-nitro-benzothiazol-2-yl)-
1343 (N=N), 1248 (C-NO2), 815 (C-Cl), 723 (C-S), 550 (C-Br)
azetidin-2-one
4-[5-Bromo-2-hydroxy-3-(4-nitro-phenylazo)-phenyl]- 202, 371 3397 (C-OH), 2920 (C-H alkyl), 1606 (C=N), 1545, 1254 (C-
I8c
I8d
I8e
I8f
3-chloro-1-(6-fluoro-benzothiazol-2-yl)-azetidin-2-one
NO2), 1332 (N=N), 1254 (C-NO2), 1450 (C-F), 807 (C-Cl), 695
(C-S), 650 (C-Br)
4-[5-Bromo-2-hydroxy-3-(4-nitro-phenylazo)-phenyl]- 219, 257, 3384 (C-OH), 2965 (C-H alkyl), 1578 (C=N), 1466, 1254 (C-
3-chloro-1-(4,6-difluoro-benzothiazol-2-yl)-azetidin-2-
one
371
NO2), 1332 (N=N), 1450 (C-F), 846 (C-Cl), 801 (C-S), 650 (C-
Br)
4-[5-Bromo-2-hydroxy-3-(4-nitro-phenylazo)-phenyl]- 221, 261, 3451 (C-OH), 2920 (C-H alkyl), 1623 (C=N), 1449, 1259 (C-
3-chloro-1-(4-methyl-6-nitro-benzothiazol-2-yl)-
azetidin-2-one
350
NO2), 1329 (N=N), 846 (C-Cl), 795 (C-S), 630 (C-Br)
4-[5-Bromo-2-hydroxy-3-(4-nitro-phenylazo)-phenyl]- 221, 352 3445 (C-OH), 2960 (C-H alkyl), 1595 (C=N), 1444 (C-NO2),
3-chloro-1-(6-nitro-benzothiazol-2-yl)-azetidin-2-one 1326 (N=N), 1259 (C-NO2), 846 (C-Cl), 795 (C-S), 640 (C-Br)
TABLE-4
1H NMR SPECTRAL DATA (δ VALUES, ppm) OF β-LACTAM DERIVATIVES (I8a-f)
Compd.
-CH aromatic
-CH benzothiazole
-CH propiolactam
-OH aromatic
5.30 (s, 1H)
8.10 (s, 2H), 7.80 (s, 2H),
7.75 (s, 1H), 7.10 (s, 1H)
8.55 (s, 2H), 8.25 (s, 2H),
7.75 (s, 1H), 6.80 (s, 1H)
8.29 (s, 2H), 7.40 (s, 2H),
7.25 (s, 1H), 7.30 (s, 1H)
8.25 (s, 2H), 8.10 (s, 2H),
6.90 (s, 1H), 6.80 (s, 1H)
8.20 (s, 2H), 8.00 (s, 2H),
7.30 (s, 1H), 7.20 (s, 1H)
8.80 (s, 2H), 8.50 (s, 2H),
7.35 (s, 1H), 7.40 (s, 1H)
I8a
7.60 (s, 1H), 7.40 (s, 1H), 7.20 (s, 2H)
5.0 (d, 1H), 4.75 (d, 1H)
I8b
I8c
I8d
I8e
I8f
8.75 (s, 1H), 8.70 (s, 1H)
7.60 (s, 1H), 7.35 (s, 1H), 7.45 (s, 1H)
7.40 (s, 1H), 7.30 (s, 1H)
5.30 (d, 1H), 5.55 (d, 1H)
5.30 (d, 1H), 5.35 (d, 1H)
5.25 (d, 1H), 5.55 (d, 1H)
5.50 (d, 1H), 4.90 (d, 1H)
5.80 (d, 1H), 5.25 (d, 1H)
5.25 (s, 1H)
5.25 (s, 1H)
5.25 (s, 1H)
4.90 (s, 1H)
5.25 (s, 1H)
7.90 (s, 1H), 7.80 (s, 1H), 2.30 (s, 3H)
8.35 (s, 1H), 7.80 (s, 1H), 7.60 (s, 1H)
The 1H NMR analysis β-lactam derivatives measured in CDCl3
solvent with TMS as an internal reference showed the two
peak at ~ 5 ppm was attributed to propiolactam and another
peak at ~ 4.5 ppm was attributed to -OH of aromatic ring. The
peaks in the range 6.9-9.2 ppm were due to aromatic protons
(Table-4).
4. A. Jarrahpour and M. Zarei, Molecules, 11, 49 (2006);
https://doi.org/10.3390/11010049
5. A.K. Bose, M.S. Manhas, J.M. van der Veen, S.S.Bari and D.R.Wagle,
Tetrahedron, 48, 4831 (1992);
https://doi.org/10.1016/S0040-4020(01)81577-5
6. N. Mast, W. Zheng, C.D. Stout and I.A. Pikuleva, Mol. Pharmacol., 84,
86 (2013);
https://doi.org/10.1124/mol.113.085902
7. P.C. Sharma, A. Sinhmar, A. Sharma, H. Rajak and D.P. Pathak, J.
Enzym. Inhib. Med. Chem., 28, 240 (2013);
CONFLICT OF INTEREST
https://doi.org/10.3109/14756366.2012.720572
8. K.C. Howard, E.K. Dennis, D.S. Watt and S. Garneau-Tsodikova, Chem.
Soc. Rev., 49, 2426 (2020);
The authors declare that there is no conflict of interests
regarding the publication of this article.
https://doi.org/10.1039/C9CS00556K
9. K.-F. Kong, L. Schneper and K. Mathee, APMIS, 118, 1 (2010);
https://doi.org/10.1111/j.1600-0463.2009.02563.x
10. S.C. Abeylath and E. Turos, Expert Opin. Drug Deliv., 5, 931 (2008);
https://doi.org/10.1517/17425247.5.9.931
11. M.F. Mojica, R.A. Bonomo and W. Fast, Curr. Drug Targets, 17, 1029
(2016);
https://doi.org/10.2174/1389450116666151001105622
12. C.M. da Silva, D.L. da Silva, L.V. Modolo, R.B.Alves, M.A. de Resende,
C.V.B. Martins and Â. de Fátima, J. Adv. Res., 2, 1 (2011);
https://doi.org/10.1016/j.jare.2010.05.004
REFERENCES
1. B. Turan, K. Sendil, E. Sengül, M.S. Gültekin, P. Taslimi, I. Gulçin and
C.T. Supuran, J. Enzym. Inhib. Med. Chem., 31(Suppl.1), 79 (2016);
https://doi.org/10.3109/14756366.2016.1170014
2. T.T. Tidwell, Angew. Chem. Int. Ed., 47, 1016 (2008);
https://doi.org/10.1002/anie.200702965
3. H.P. Ebrahimi, J.S. Hadi, A.A. Almayah, Z. Bolandnazar, A.G. Swadi
and A. Ebrahimi, Bioorg. Med. Chem., 24, 1121 (2016);
https://doi.org/10.1016/j.bmc.2016.01.041

1524 Shinde et al.
Asian J. Chem.
13. S. Samadhiya and A.K. Halve, Orient. J. Chem., 17, 199 (2001).
14. T. Eicher and S. Hauptmann, The Chemistry of Heterocycles, Wiley:
Weinheim (2003).
15. V.M. Dembitsky, T.A. Gloriozova and V.V. Poroikov, Nat. Prod.
Bioprospect., 7, 151 (2017);
19. P. Przybylski, A. Huczynski, K. Pyta, B. Brzezinski and F. Bartl, Curr.
Org. Chem., 13, 124 (2009);
https://doi.org/10.2174/138527209787193774
20. S. Slassi, A. Fix-Tailler, G. Larcher, A. Amine and A. El-Ghayoury,
Heteroatom Chem., 2019, 6862170 (2019);
https://doi.org/10.1007/s13659-016-0117-3
https://doi.org/10.1155/2019/6862170
16. E. Wagner-Wysiecka, N. Lukasik, J.F. Biernat and E. Luboch, J. Incl.
Phenom. Macrocycl. Chem., 90, 189 (2018);
21. M. Ikiz, E. Ispir, E. Aytar, M. Ulusoy, S. Karabuga, M. Aslantas and
Ö. Çelik, New J. Chem., 39, 7786 (2015);
https://doi.org/10.1007/s10847-017-0779-4
https://doi.org/10.1039/C5NJ00571J
17. N.M. Aljamali, Biochem. Anal. Biochem., 4, 169 (2015);
https://doi.org/10.4172/2161-1009.1000169
22. Ö. Özdemir, Turk. J. Chem., 43, 266 (2019);
https://doi.org/10.3906/kim-1807-24
18. E. Weglarz-Tomczak and L. Górecki, Chemik, 66, 1298 (2012).