Synthesis and antibacterial studies of some reduced schiff base derivatives

Article abstract of DOI:10.13005/ojc/340616

A series of N,N-substituted ethylene-1,2-diamine derivatives have been prepared from reaction of 2-hydroxybenzaldehyde derivatives and 1,2-diamine derivatives in the presence of NaBH₄ through Schiff base intermediate. The synthesized compounds were screened for their antibacterial activities. Compound SB01, SB02 and SB09 displayed significant activity at MIC ranges from 0.40-6.25 μg/mL.

Full text of DOI:10.13005/ojc/340616

ISSN: 0970-020 X
CODEN: OJCHEG
2018, Vol. 34, No.(6):
Pg. 2796-2805
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Access Peer Reviewed Research Journal
www.orientjchem.org
Synthesis and Antibacterial Studies of Some Reduced
Schiff base Derivatives
UDAYSINHA PATIL1, ASIF KHAN1, AARTI NAGARSEKAR1,
MUSTAPHA MANDEWALE1 and RAMESHYAMGAR*2
1Department of Chemistry, Government of Maharashtra’s Ismail Yusuf College of Arts, Science and
Commerce, Jogeshwari (East), Mumbai, India.
2Department of Chemistry, Chikitsak Samuha’s Patkar-Varde College of Arts, Science and
Commerce, Mumbai, India.
http://dx.doi.org/10.13005/ojc/340616
Received: July 13, 2018; Accepted: December 09, 2018)
ABSTRACT
A series of N,N-substituted ethylene-1,2-diamine derivatives have been prepared from reaction
of 2-hydroxybenzaldehyde derivatives and 1,2-diamine derivatives in the presence of NaBH4 through
Schiff base intermediate. The synthesized compounds were screened for their antibacterial activities.
Compound SB01, SB02 and SB09 displayed significant activity at MIC ranges from 0.40-6.25 µg/mL.
Keywords: Schiff bases, Reduction, Antibacterial, MIC, Antituberculosis, Bioactive.
INTRODUCTION
of ketone. Moreover, the extra carbon of ketone
releases more electron density to the azomethine
carbon and therefore makes the ketone less
electrophilic as compared to aldehydes2.
Schiff bases are synthesized typically
by the condensation reaction of a primary amine
and an aldehyde/ketone. The resultant compound,
R1R2C=NR3 is called a Schiff base, where R1 is an
aryl or alkyl group, R2 is a hydrogen atom and R3
is either an alkyl or aryl group. The ary substituted
Schiff bases are considerably more stable and easily
prepared, while Schiff bases with alkyl substituents
are comparatively less stable1, while those of
aromatic aldehydes having effective conjugation are
more stable.In general, aldehydes are more reactive
than ketones in condensation reactions, leading to
the formation of Schiff bases as the reaction center
of aldehydes are sterically less hindered than that
Schiff base derivatives have a wide variety
of applications in pharmaceutical, analytical
chemistry3-4. Transition metal complexes of Schiff
bases have extremely significant comprising
enormous areas of coordination compounds5. The
synthesis of symmetrical Schiff bases obtained from
reaction of carbonyl compounds, with substituted
diamines in the ratio 1:2 and various aldehyde/ketone
derivatives. Recently large amount of effort has been
taken for the preparation and identification of different
coordination complexes of Schiff base ligands6.
This is an
Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC- BY).
Published by Oriental Scientific Publishing Company © 2018

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YAMGAR et al., Orient. J. Chem., Vol. 34(6), 2796-2805 (2018)
Schiff base ligands are important in the
studies of coordination complexes since they
essentially produce stable complexes7. Schiff base
reactions are significant in organic reactions for
preparing carbon-nitrogen bonds.Schiff bases have
often known to form chelates type complexes. The
suitabely positioned heteroatoms like O, N and S are
key atoms in the formation of coordination complexes
in the structures of various metallobiomolecules8.
This class of compounds have been widely studied
for their antiviral, antifungal, anticancer, antibacterial
and herbicidal activities9-11. It is common that
the incorporation of metal ions to structure of
biologically important compounds may improve their
potencies.
by using common and mild reducing agent like
Sodium borohydride. This could improve properties
of the the reduced Schiff base and the resultant
compound could be more flexible and non-planar
while coordinating to a metal ion25-26
.
Recently it is reported that reduced Schiff
base derivative showed significant antimicrobial
activity at low concentration level27. Voronova
et al.,28 reportedexcellentcatalystfortheSonogashira
coupling reaction. Further, various types of reduced
Schiff base ligands and their Iorn centered complexes
have gained mored attraction in the field of medicinal
chemistry due to their effective DNA cleavage activity
29.It is evident from the literature that partially reduced
Schiff base moieties are known to show excellent
The salophens exhibit flexible electronic,
steric and lipophilic nature.These type of componds
can be easily synthesized by the reaction of
o-hydroxybenzaldehyde and 1,2-diamines.Salophen
compounds with nitrogen and oxygen atoms are
significant as their metal complexes show broad
range of applications in a variety of reactions
as homogeneous catalysis12-13, Oxidation14,
hydroxylation15, Epoxidation16, Polymerization17,
Hydrogenation18. These compounds also found
catalyst for oxidation of various phenols 30
.
Based on above observation and in
extension of our research work for finding better
antimicrobial copunds31-36 we found that it was worth
trying to synthesize various reduced Schiff bases
derivatives with expected antibacterial activity.
EXPERIMENTAL
applications as electroluminescent materials19-20
,
General procedure for preparation of schiff bases
A solution of aldehyde derivative (4 mmol)
optical devices21, electrochemical sensors22,
antifungal23 and antimicrobial activity24.
and 1, 2-diamine derivative 1a-1c (2.0 mmol) in EtOH
(8 mL) maintained for 2 h at 700C under stirring.
Reaction completion monitored with TLC. Reaction
mass cooled to room temperature and the solid
obtained was filtered and dried.
Generally Schiff bases have tendence
to under go hydrolysis in solution phase. This
problem overcome by reducing the imine bond
R1
R2
R1
R2
N
X
X
X
X
X
NaBH4
MeOH
R
NH HN
OH HO
R1
R2
N
MeOH
O
+
R
R
H2N
NH2
OH
Aldehyde
R= H, Br
X= H, CH3
R
R
OH HO
Diamine
1a-1c
RSB01-RSB09
SB01-SB09
Fig. 1. Preparation of [RSB01-RSB09]
2,2’-{ethane-1,2-diylbis[azanylylidene(E)methany
lylidene]}diphenol [SB01]
4H) 13.358 (s, 2H);Elemental analysis [C16H16N2O2]:
observed (Calculated):C 71.92% (71.62%), H 5.87%
(6.01%), N 10.76% (10.44%).
m.p.:125-1270C;Colour:Yellow;EIMS [M+2]:269.23;
FTIR(KBr cm-1): 3025, 2940, 2906, 2873, 2738,
1635, 1477, 1361, 1276, 1186, 1033, 827, 777,
628; 1H-NMR (300 MHz, DMSO-d6) δ: 3.895 (s, 2H),
6.825-6.884 (m, 4H), 7.271-7.409 (m, 4H), 8.565 (m,
2,2'-{1,2-Phenylenebis[azanylylidene(e)methany
lylidene]}diphenol [sb02]
m.p.:154-1560C;Colour:Yellow;EIMS [M+2]:318.22;

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YAMGAR et al., Orient. J. Chem., Vol. 34(6), 2796-2805 (2018)
FTIR(KBr cm-1): 3056, 2734, 1614, 1562, 1481,
1H NMR (300 MHz, DMSO-d6) δ: 3.335 (s,2H), 7.222-
7.899 (m, 3H), 8.116-8.145 (m, 3H), 8.925-8.953
1
1363, 1276, 1191, 977, 910, 759; H NMR (300
MHz, DMSO-d6) δ:6.930-6.978 (m, 4H), 7.398-7.430
(m, 4H), 7.635-7.658 (m, 4H), 8.916 (s, 2H), 12.904
(s, 2H);13C NMR (75MHz, DMSO-d6) δ:162.2, 162.1,
161.3, 161.1, 136.3, 136.2, 132.4, 132.3, 131.9,
131.7, 129.2, 129.1, 124.3, 124.2, 119.3, 119.2,
119.1, 119.1, 117.3, 117.1; Elemental analysis
[C20H16N2O2]: observed (Calculated): C 75.79%
(75.93%), H 5.16% (5.10%), N 8.94% (8.86%).
(m, 4H), 10.805 (s, 2H);; 13C NMR (75MHz, DMSO-d6)
δ: 162.2, 162.1, 161.3, 161.1, 136.3, 136.2, 132.4,
132.3, 131.9, 131.7, 129.2, 129.1, 124.3, 124.2, 119.3,
119.2, 119.1, 119.1, 117.3, 117.1;Elemental analysis
[C20H14Br2N2O2]: observed (Calculated): C 50.61%
(50.66%), H 3.05% (2.98%), N 5.88% (5.91%).
2-((E)-(2-((E)-5-bromo-2-hydroxybenzylideneamino)
-4-methylphenylimino)methyl)-4-bromophenol [SB06]
m.p.: 187-1890C; Colour: Yellow; EIMS
2,2’-{(4-methyl-1,2-phenylene)bis[azanylylidene
(E) methanylylidene]} diphenol [SB03]
m.p.: 162-1640C; Colour: Yellow; EIMS
[M+H]: 331.43; FTIR(KBr cm-1): 3054, 2985, 2917,
[M+H]: 487.54; FTIR(KBr cm-1): 3055, 2985, 2918,
2713, 1616, 1564, 1487, 1365, 1279, 1190, 1151,
1115, 1032, 995, 908, 839, 767, 738, 638, 503;
1H-NMR (300 MHz, DMSO-d6) δ: 2.389 (s, 3H), 6.918-
6.962 (m, 3H), 7.228-7.898 (m, 3H), 8.909-8.917 (m,
3H), 12.910(s, 1H), 13.091(s, 1H);Elementalanalysis
[C21H16Br2N2O2]: observed (calculated): C 51.61%
(51.67%), H 3.33% (3.30%), N 5.68% (5.74%).
2713, 1616, 1563, 1486, 1365, 1278, 1189, 950,
1
757, 638; H NMR (300 MHz, DMSO-d6) δ: 2.389
(s, 3H), 6.936-6.973 (m, 4H), 7.204-7.282 (m, 2H),
7.379-7.405 (m, 3H), 7.630-7.677 (m, 2H), 8.927
(s, 2H), 12.950 (s, 1H), 13.070 (s, 1H); 13C NMR
(75MHz, DMSO-d6) δ: 162.3, 162.1, 161.2, 161.1,
136.3, 136.2, 132.4, 132.4, 132.3, 131.8, 131.7,
126.1, 125.1, 124.5, 119.2, 119.2, 119.1, 119.1,
117.3, 117.1, 21.2;Elemental analysis [C21H18N2O2]:
observed (Calculated):C 76.40% (76.34%), H 5.41%
(5.49%), N 8.55% (8.48%).
2-((E)-1-(2-((E)-1-(2-hydroxyphenyl)ethylideneamino)
ethylimino)ethyl)phenol [SB07]
m.p.:190-1920C; Colour: Yellow; EIMS
[M+2]: 296.32; FTIR(KBr cm-1): 3458, 3242, 3093,
2902, 1662, 1604, 1574, 1475, 1382, 1337, 1288,
1182, 1146, 1072, 1039, 934, 808, 656, 576;
1H-NMR (300 MHz, DMSO-d6) δ:2.608 (s, 3H), 2.481
(s, 3H), 3.895 (s, 4H), 6.829-6.884 (m, 4H), 7.271-
7.409 (m, 4H), 13.358 (s, 2H); Elemental analysis
[C18H20N2O2]: observed (Calculated): C 72.70%
(72.95%), H 6.84% (6.80%), N 9.42% (9.45%).
2-((E)-(2-((E)-5-bromo-2-hydroxybenzylideneamino)
ethylimino)methyl)-4-bromophenol [SB04]
m.p.: 192-1940C; Colour: Yellow; EIMS
[M+2]: 427.5; FTIR(KBr cm-1): 3026, 2940, 2906,
2873, 2738, 1635, 1567, 1477, 1392, 1361, 1276,
1218, 1186, 1079, 1033, 977, 914, 827, 777,
1
692, 628; H-NMR (300 MHz, DMSO-d6) δ: 3.922
2-((E)-1-(2-((E)-1-(2-hydroxyphenyl)ethylideneamino)
phenylimino)ethyl)phenol [SB08]
(s, 2H), 6.823-6.853(m, 3H), 7.438-7.650(m, 3H),
8.57 (m, 4H) 13.45 (s, 2H); Elemental analysis
[C16H14Br2N2O2]: observed (Calculated): C 45.14%
(45.1%), H 3.38% (3.31%), N 6.60% (6.67%).
m.p.:194-1960C;Colour:Yellow;MS [M+2]:
345.34; FTIR(KBr cm-1): 3319, 3157, 2983, 2877,
2829, 1660, 1612, 1551, 1479, 1394, 1321, 1290,
1184, 1070, 1004, 933, 816, 752, 682, 634, 586.;
1H NMR (300 MHz, DMSO-d6) δ:2.316 (s, 6H), 6.607-
6.963 (m, 4H), 7.360-7.410 (m, 4H), 7.735-7.761 (m,
4H), 15.025 (s, 2H);Elemental analysis [C22H20N2O2]:
observed (Calculated):C 76.79% (76.73%), H 5.88%
(5.85%), N 8.18% (8.13%).
2-((E)-(2-((E)-5-bromo-2-hydroxybenzylideneamino)
phenylimino)methyl)-4-bromophenol. [SB05]
m.p.: 186-1880C; Colour: Yellow; EIMS
[M+2]: 475.41; FTIR(KBr cm-1): 3056, 2734, 1614,
1585, 1562, 1481, 1450, 1363, 1277, 1192, 1151,
1045, 977, 910, 856, 831, 787, 759, 640, 580.;

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Table 1: Structure of Schiff bases [SB01-SB09]
Entry
SB01
Diamine
Product
Yield(%)
N
N
96
H2N
NH2
OH HO
SB02
N
94
N
H2N
NH2
OH HO
CH3
CH3
NH2
SB03
SB04
96
94
N
N
H2N
H2N
OH HO
N
N
NH2
OH HO
Br
Br
SB05
SB06
93
91
N
N
H2N
NH2
OH HO
CH3
Br
Br
CH3
NH2
N
N
H2N
OH HO
Br
Br
N
N
SB07
SB08
89
92
H2N
NH2
OH HO
N
N
H2N
NH2
OH HO
CH3
CH3
NH2
SB09
90
N
N
H2N
OH HO
2-((E)-1-(2-((E)-1-(2-hydroxyphenyl)ethylideneamino)-
4-methylphenylimino)ethyl)phenol [SB09]
dichloromethane (10 mL). Reaction mass cooled at
00C and 2-3 drops of conc.KOH solution added.The
solution of NaBH4 (2.0 mmol) in methanol added
dropwise. Reaction mass stirred for 4-5 h until the
yellow colour disappeared. Reaction monitored on
TLC.After completion of reaction solvent distilled and
cold water (10 mL) added to dissolve residue. pH
adjusted to 4-5 by addition of dilute HCl. The white
solid filtered, washed with water dried.
m.p.: 193-1950C; Colour:Yellow; MS [M+H]:
359.50; FTIR(KBr cm-1): 3186, 3053, 2922, 2843,
1662, 1616, 1566, 1479, 1415, 1255, 1209, 1178,
1103, 980, 945, 820, 770, 667, 599, 588;1HNMR(300
MHz, DMSO-d6) δ:2.196 (s, 6H), 2.389 (s,3H), 6.918-
6.962 (m, 4H), 7.228-7.404 (m, 4H), 7.539 (m, 3H),
12.910 (s, 1H), 13.091 (s, 1H); Elemental analysis
[C23H22N2O2]: observed (Calculated): C 77.40%
(77.07%), H 6.13% (6.19%), N 7.80% (7.82%).
2,2’-[ethane-1,2-diylbis(azanediylmethylene)]diphenol
[RSB01]
General procedure for preparation of reduced
schiff bases
m.p.: 1180C; Colour: white; MS [M+2]:
273.99; FTIR(KBr cm-1): 3490, 3463, 3363, 3052,
2942, 2852, 2593, 1602, 1479, 1417, 1353, 1268,
The Schiff base (2.27 mmol) dissolved in

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YAMGAR et al., Orient. J. Chem., Vol. 34(6), 2796-2805 (2018)
1189, 1126, 1074, 960, 815, 757, 626;1H NMR (300
MHz, DMSO-d6) δ: 2.481 (m, 4H), 3.770 (s, 4H),
5.031 (s, 2H), 6.658-6.686 (m, 4H), 7.01-7.06 (m,
4H), 13.335 (s, 2H);Elemental analysis [C16H20N2O2]:
observed (Calculated):C 70.63% (70.56%), H 7.31%
(7.40%), N 10.34% (10.29%).
DMSO-d6) δ: 2.481 (m, 2H), 2.608 (m, 2H), 3.332 (s,
1H), 3.922 (s, 1H), 5.031 (s, 4H), 6.823-6.853 (m, 3H),
7.438-7.656(m, 3H), 13.450(s, 2H);Elementalanalysis
[C16H18Br2N2O2]: observed (Calculated): C 44.70%
(44.68%), H 4.25% (4.22%), N 6.48% (6.51%).
2-((2-(5-bromo-2-hydroxybenzylamino)phenylamino)
methyl)-4-bromophenol [RSB05]
m.p.: 132-1340C; Colour: white; MS [M+]:
475.97; FTIR(KBr cm-1): 3415, 3193, 3116, 3008,
2954, 1617, 1567, 1471, 1432, 1286, 1281, 1238,
2,2’-[1,2-phenylenebis(azanediylmethylene)]diphenol
[RSB02]
m.p.: 138-1400C; Colour: white; MS [M+]:
320.13; FTIR(KBr cm-1): 3394, 3359, 3289, 3041,
2852, 1696, 1456, 1315, 1238, 1103, 1025, 929,750,
636; 1H NMR (300 MHz, DMSO-d6) δ: 4.236 (s, 4H),
5.068 (s, 2H), 6.37-6.450 (m, 3H), 6.758-6.843 (m,
3H), 7.023-7.070 (m, 3H), 7.176-7.222 (m, 3H),
10.805 (s, 2H);13C NMR (75MHz, DMSO-d6) δ: 157.6,
157.5, 141.1, 141.0, 131.8, 131.8, 128.9, 128.8,
123.2, 123.1, 122.6, 122.6, 121.8, 121.8, 120.6,
120.6, 116.1, 116.0, 45.9, 45.8; Elemental analysis
[C20H20N2O2]: observed (calculated): C 75.04%
(74.98%), H 6.32% (6.29%), N 8.77% (8.74%).
1
1214, 1103, 966, 794, 752, 609; H NMR (300
MHz, DMSO-d6) δ: 4.236 (s, 1H), 3.33 (s, 1H), 5.082
(s, 4H), 6.39-6.769 (m, 3H), 6.902-7.289 (m, 3H),
7.489-7.902(m,4H),12.666(s,2H);Elementalanalysis
[C20H18Br2N2O2]: observed (calculated): C 50.28%
(50.24%), H 3.84% (3.79%), N 5.82% (5.86%).
2-((2-(5-bromo-2-hydroxybenzylamino)-4-methylpheny
lamino)methyl)-4-br omophenol [RSB06]
m.p.: 127-1290C; Colour: white; MS [M+H]:
335.57; FTIR(KBr cm-1): 3517, 3455, 3397, 3189,
3143, 3066, 2886, 2807, 1612, 1573, 1517, 1430,
1376, 1294, 1236, 1191, 1130, 1047, 968, 968, 935,
848, 784, 745, 572, 524, 485; 1H-NMR (300 MHz,
DMSO-d6) δ: 2.316 (s, 3H), 4.146 (s, 2H), 5.102
(s, 4H), 7.056-7.282 (m, 3H), 7.363-7.643 (m, 3H),
7.813-8.146 (m, 3H), 15.122 (s, 1H), 15.649 (s,
1H); Elemental analysis [C21H20Br2N2O2]: observed
(calculated):C 51.30% (51.24%), H 4.08% (4.10%),
N 5.63% (5.69%).
2,2’-[(4-methyl-1,2-phenylene)bis(azanediylmethylene)]
diphenol [RSB03]
m.p.:136-1380C;Colour:White;MS [M+H]:
335.57; FTIR(KBr cm-1): 3390, 3359, 3278, 2852,
1696, 1455, 1305, 1251, 1110, 935, 844, 800, 752;
1H NMR (300 MHz, DMSO-d6) δ: 2.055 (s, 3H),
4.191 (s, 4H), 4.987 (s, 2H), 6.267-6.385 (m, 2H),
6.655-6.818 (m, 5H), 7.024 (m, 2H), 7.172-7.195
(m, 2H), 12.666 (s, 1H), 12.904 (s, 2H); 13C NMR
(75MHz, DMSO-d6) δ: 157.6, 157.5, 141.1, 134.7,
132.9, 131.9, 131.8, 128.9, 128.8, 124.2, 123.2,
123.1, 120.7, 120.5, 118.8, 116.2, 116.1, 114.9,
45.9, 45.8, 21.2, Elemental analysis [C21H22N2O2]:
observed (Calculated):C 75.34% (75.42%), H 6.72%
(6.63%), N 8.30% (8.38%).
2-(1-(2-(1-(2-hydroxyphenyl)ethylamino)ethylamino)
ethyl)phenol [RSB07]
m.p.: 121-1230C; Colour: white; MS
[M+1]: 301.23; FTIR(KBr cm-1): 3227, 3153, 3045,
2998, 2944, 2892, 2840, 1617, 1556, 1488, 1432,
1413, 1290, 1261, 1213, 1151, 1071, 956, 898,
846, 755, 684, 636, 603, 426; 1H NMR (300 MHz,
DMSO-d6) δ: 1.288 (s, 6H), 3.836 (m, 4H), 3.857
(s, 2H), 5.05 (s, 2H), 6.360-6.723 (m, 4H), 6.992-
7.056 (m, 4H),12.259 (s, 2H); Elemental analysis
[C18H24N2O2]: observed (Calculated): C 71.90%
(71.97%), H 8.10% (8.05%), N 9.39% (9.33%).
2-((2-(5-bromo-2-hydroxybenzylamino)ethylamino)
methyl)-4-bromophenol [RSB04]
m.p.: 128-1300C; Colour: white; MS [M+2]:
273.99;FTIR(KBr cm-1):3303,3232,3097,1621,1579,
1502, 1481, 1384, 1309, 1282, 1267, 1224, 1195,
1130, 1079, 1022, 1000, 763, 734;1H NMR (300 MHz,

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YAMGAR et al., Orient. J. Chem., Vol. 34(6), 2796-2805 (2018)
Table 2: Structures of reduced Schiff bases
Biological evaluation
[RSB01-RSB09]
Anti-mycobacterial activity
The anti-microbial activities of the newly
prepared compounds evaluated against M.
tuberculosis ATCC No- 27294 by microplate Alamar
Blue assay (MABA). A blue colour in the well was
indicates bacterial growth whereas pink colour show
growth of bacteria.
Entry
Product
Yield(%)
NH HN
OH HO
RSB01
87
RSB02
NH HN
OH HO
85
CH3
RSB03
RSB04
82
89
NH HN
OH HO
RESULTS AND DISCUSSIONS
NH HN
Chemistry
OH HO
Br
Br
The target compounds RSB01-RSB09
were prepared as outlined in Fig. 1. The required
Schiff bases (SB01-SB09) were obtained by
condensation reaction of requisite aldehydes and
amines. The compounds (RSB01-RSB09) were
prepared by reduction of imine bond of compounds
with reducing agent like NaBH4 in quantitative yield.
Elemental analysis and spectral data (FTIR, 1H
and 13C-NMR, MS) confirmed the structure of the
synthesized products. The IR spectrum of Schiff
bases SB01-SB09 showed strong absorption
bands at 1614-1616 cm-1 and 3100-3400 cm-1 due
to imine (-HC=N-) function and hydroxyl (-OH)
group respectively, The 1H-NMR spectrum of Schiff
bases SB01-SB09 revealed, in addition to expected
aromatic signals, three singlets at δ 8.91 and 12.95
ppm are assignable to the azomethine proton
(-CH=N-) and hydroxyl proton (-OH), respectively.
In addition, the 13C-NMR spectrum of Schiff bases
SB01-SB03 displayed typical peaks at δ 161.0-161.5
ppm assignable to imine carbon.Moreover the mass
spectrum of Schiff bases revealed molecular ion
peak confirming corresponding molecular weight of
target compounds.
RSB05
RSB06
NH HN
OH HO
88
86
Br
Br
CH3
NH HN
OH HO
Br
Br
NH HN
OH HO
RSB07
RSB08
81
80
NH HN
OH HO
CH3
RSB09
83
NH HN
OH HO
2-(1-(2-(1-(2-hydroxyphenyl)ethylamino)phenylamino)
ethyl)phenol [RSB08]
m.p.:136-1380C;Colour:white;MS[M+]:348.78;
FTIR(KBr cm-1): 3417, 3273, 3190, 1620, 1579, 1508,
1454, 1402, 1299, 1232, 1165, 1082, 1057, 1014, 879,
804, 687, 613, 518;1HNMR(300MHz, DMSO-d6)δ:2.045
(s,6H), 2.861 (s,2H), 5.214 (s, 2H), 6.664-7.343 (m, 4H),
7.508-7.532(m, 4H), 7.735-7.849(m,4H), 12.031(s, 2H);
Elemental analysis [C22H24N2O2]:observed (Calculated):
C 75.78% (75.83%), H 6.90% (6.94%), N 8.10%
(8.04%).
The FTIR spectra of reduced Schiff
base RSB02 showed broad peak in the region
3289-3394 cm-1 due to amino (-NH-) and hydroxyl
group, respectively. The 1H-NMR spectrum of
reduced Schiff bases RSB02 showed, in addition to
expected aromatic signals, three singlets at δ 5.03
and 13.33 ppm are assignable to the amino (-NH-)
and hydroxyl proton (-OH), respectively.The singlet
at δ 4.2 due to –CH2- group confirms the formation
of reduced Schiff bases. Additionally the mass
spectrum of reduced Schiff base RSB02 revealed
molecular ion peak at m/z 320.13 confirming it’s
molecular weight of target compound.Similarly other
reduced Schiff bases have been characterized.
2-(1-(2-(1-(2-hydroxyphenyl) ethylamino)-4-
methylphenylamino) ethyl) phenol [RSB09]
m.p.: 122-1240C; Colour: white; MS
[M+H]: 363.24; FTIR(KBr cm-1): 3539, 3433, 3118,
3003, 2938, 2843, 1657, 1564, 1471, 1425, 1329,
1292, 1263, 1232, 1182, 1101, 976, 865, 738, 595;
1H-NMR (300 MHz, DMSO-d6) δ: 2.371 (s, 6H),
2.555 (s, 3H), 3.338 (s, 2H), 5.107 (s, 2H), 7.201-
7.253 (m, 4H), 7.331-7.508 (m, 4H), 7.708 (m, 3H),
11.781 (s,1H), 12.388 (s, 1H); Elemental analysis
[C23H26N2O2]: observed (calculated): C 76.32%
(76.26%), H 7.22% (7.23%), N 7.70% (7.73%).

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YAMGAR et al., Orient. J. Chem., Vol. 34(6), 2796-2805 (2018)
Table 3: Antibacterial activity of the test samples in MIC (mg/mL)
Sr. No.
Entry
M. Tuberculosis
E. coli
P. aeruginosa
S. aureus
B. subtilis
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
SB-01
SB-02
SB-03
SB-04
SB-05
SB-06
SB-07
SB-08
SB-09
12.50
25.00
50.00
50.00
50.00
50.00
25.00
25.00
25.00
12.50
50.00
50.00
50.00
50.00
50.00
50.00
50.00
50.00
3.125
3.125
6.250
12.50
25.00
25.00
50.00
50.00
50.00
25.00
50.00
12.50
12.50
25.00
50.00
50.00
50.00
50.00
50.00
50.00
25.00
2.00
3.12
3.12
50.00
6.25
12.50
6.25
6.25
6.25
1.60
12.50
0.40
12.50
1.60
12.50
12.50
6.25
3.12
3.12
25.00
0.40
2.00
-
6.25
3.12
6.25
12.50
50.00
25.00
12.50
25.00
6.25
3.12
25.00
6.25
25.00
50.00
25.00
25.00
25.00
25.00
12.50
<4.00
-
12.50
50.00
12.50
25.00
12.50
12.50
3.12
25.00
25.00
12.50
25.00
12.50
12.50
25.00
12.50
2.00
RSB-01
RSB-02
RSB-03
RSB-04
RSB-05
RSB-06
RSB-07
RSB-08
RSB-09
Ciprofloxacin
Pyrazinamide
Streptomycin
-
-
-
-
-
-
Anti-mycobacterial activity
The anti-mycobacterial effects of the
cell wall of the M. tuberculosis, which translated into
good activity. In addition, these compounds interfere
the respiration process of the cell and thereby stop
the synthesis of proteins. If the synthesis of proteins is
inhibitedthenformationbacterialcellwallisnotpossible
which ultimately results in cell death and therefore
restricts further growth and infection of the bacteria.
schiff base derivatives compounds SB01-SB09 and
RSB01-RSB09 against Mycobacterium tuberculosis.
The Ciprofloxacin (MIC 3.12 mg/mL), Pyrazinamide
(MIC 3.12 mg/mL) and Streptomycin (MIC 6.25
mg/mL) were used as references to compare the
potency of the synthesized compounds. As shown
in table 3 compounds SB01 has unpredictable high
anti-tuberculosis activity against Mycobacterium
tuberculosis as its MIC value is 12.50 µg/mL. This
could be due to formation a specific complex with
cell wall protein and ultimately interfering in cell wall
synthesis of Mycobacterium tuberculosis during
cell mitosis phase of multiplication. The presence
of active pharmacophore present in the molecular
structure of the compound, like imine double bond
between carbon and nitrogen and well positioned
hydroxyl group, these structural units restrict in the
mechanism of cell multiplication and hence stop
further growth of M. tuberculosis. All the samples
under study are diplaying different activity because
of the effective barrier of an outer cell wall membrane
of M. tuberculosis for entry of external compounds.
The results of anti-mycobacterial activity
of all compounds SB01-SB09 and RSB01-RSB09
is shown in Table 3. The compound RSB01-RSB09
showed poor activity as compared to SB01-SB09
suggesting that the imine moiety was important to
activity. Clearly, the presence of Schiff base moiety
is crucial for anti-tubercular activity.
Antibacterial activity
Ciprofloxacin was used as references
to evaluate the potency of the synthesized
compounds against Escherichia coli (MIC 2.00
mg/mL), Pseudomonas aeruginosa (MIC <4.00
mg/mL), staphylococcus aureus (MIC 2.00 mg/mL),
bacillus subtilis (MIC 2.00 mg/mL). The compounds
SB01-SB09showedexcellentantibacterialantibacterial
activity as compared to their reduced forms RSB01-
This outcome indicates that suitably placed
pharmacophores improved the penetration into the

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YAMGAR et al., Orient. J. Chem., Vol. 34(6), 2796-2805 (2018)
RSB09.This also predicts the importance of the imine
ACKNOWLEDGEMENT
bond for the antibacterial activity.
The authors thank Principal and Head
Department of Chemistry, Government of Maharashtra,
Ismail Yusuf Arts, Science and Commerce College for
providing research and library facilities. The authors
also thank Management and Principal of C. S.’s
Patkar-Varde College, Goregaon (W), Mumbai for their
constant encouragement and support.The authors also
acknowledgethehelpofDr.KishoreBhatofGovernmental
Dental College, Belgaum, for anti-TB study.
CONCLUSION
In conclusion, the synthesis of 18
compounds were easily performed with good yields.
All compounds were tested against M. tuberculosis,
E. coli, P. aeruginosa, S. aureus, B. subtilis three of
them (SB01, SB02 and SB09) exhibit considerable
activity when compared with standard drugs like
Ciprofloxacin, Pyrazinamide and Streptomycin.
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