Synthesis, Characterization, Anticorrosion Activities and Antibacterial Activities of New Schiff Bases

Eissa HH, BAOJ Chem 2015 1:11: 001

BAOJ Chem, an open access journal Volume 1; Issue 1; 001

*Eissa HH*Department of Physical organic Chemistry –Chemistry, Applied College Sciences, University of Hajah, Yemen

BAOJ Chemistry

*Corresponding author: Eissa HH, Assistant Professor in Physical organic Chemistry -Chemistry Department, Applied College Sciences, University of Hajah, Yemen. E-mail: hamedesia2003@yahoo.com

Sub Date: April 23, 2015, Acc Date: May 14, 2015, Pub Date: May 15, 2015

Citation: Eissa HH (2015) Synthesis, Characterization, Anticorrosion Activities and Antibacterial Activities of New Schiff Bases. BAOJ Chem 1: 001.

Copyright: © 2015 Eissa HH. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

AbstractSchiff bases are very important in medicinal and pharmaceutical fields because of their wide spectrum of biological activities. Most of them show biological activities such as antibacterial, antifungal as well as antitumor activity. Transition metal complexes derived from the Schiff base ligands with biological activity have been widely studied. This research paper has been aimed at the synthesis of some novel Schiff bases (from isatin and diamines) of biological importance. The synthesized Schiff bases have been characterized by IR, NMR, Mass Spectra followed by Elemental analysis for carbon, hydrogen and nitrogen. All the compounds have been screened for their in vitro antibacterial activity against two Gram +ve (Staphylococcus aureus, Bacillus subtilis) and two Gram –ve (Escherichia coli, Pseudomonas aeruginosa) bacterial strains by disc diffusion method. The Schiff bases have been found to exhibit varied activity against different bacterial species, these compounds were tested to determine their ability to inhibit corrosion of mild steel in 1 M H2SO4 .

Keywords: Schiff bases; isatin; diamines; Spectral study; antibacterial activities; anticorrosion; mild steel.

IntroductionCompounds containing an azomethine group (-CH=N-), known as Schiff bases are formed by the condensation of a primary amine with a carbonyl compound. Schiff bases of aliphatic aldehydes are relatively unstable and are readily polymerizable while those of aromatic aldehydes, having an effective conjugation system, are more stable. Schiff bases have number of applications viz, preparative use, identification, detection and determination of aldehydes or ketones, purification of carbonyl or amino compounds, or protection of these groups during complex or sensitive reactions. They also form basic units in certain dyes. In organic synthesis, Schiff base reactions are useful in making carbon-nitrogen bonds. Schiff bases appear to be an important intermediate in a number of enzymatic reactions involving interaction of an enzyme with an amino or a carbonyl group of the substrate. One of the most important types of catalytic mechanism is the biochemical process which involves the condensation of a primary amine in an enzyme usually that of a lysine residue, with a carbonyl group of the substrate to form an imine, or Schiff base [6]. The most efficient organic inhibitors are organic compound as an inhibitor is mainly dependent on its ability to get adsorbed on metal surface which consists of a replacement of water molecule at a corroding interface as :

Org (sol) + nH2O (ads) Org (ads) + n H2O (sol)

The adsorption of these compounds is influenced by the electronic structure of inhibiting molecules, steric factor, aromaticity and electron density at donor site, presence of functional group such as –CHO,-N=N,R-OH,ETC, molecular area and molecular weight of the inhibitor molecule [11], Isatin is chemically 1H-indole-2,3-dione and is a versatile lead molecule for potential bioactive agents and its derivatives were reported to posses wide spectrum of activity like antibacterial, antifungal, anticonvulsant, anti HIV, antidepressant, anti-inflammatory, and anticancer. Also isatin, have been extensively used as versatile reagents in organic synthesis: to obtain heterocyclic compounds and as raw material for drugs [10].

The Schiff bases of isatin have been used as ligand for complexation of metals such as copper(II) [9] and also Schiff base derivatives of indolin-2,3-dione (isatin) as recent reports documented a remarkable ant proliferative activity of isatin nucleus against various cancer cell lines [12].

In the light of these findings, we reported here the synthesis of novel heterocyclic compounds derived from isatin and the newly synthesized compounds were characterized by elemental analysis, IR, 1H- and 13C-NMR spectral data and investigation their antibacterial activity.

ExperimentalReagents and Apparatus.

All the chemicals used were of AnalaR grade and procured from Sigma-Aldrich and Fluka.Metal salts were purchased from E. Merck and were used as received. Distilled water was used in

Research Article

BAOJ Chem, an open access journal Volume 1; Issue 1; 001

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extraction experimental. The solvents were saturated with each other before use in order to prevent volume changes of the phases during extraction. All compounds were routinely checked by TLC on silica gel G plates using Mixture of petroleum ether/ethyl acetate (7:3; 6:4; 5:5 by V/V) used as mobile phase and the developed plates were visualized by UV light, iodine vapour and KMnO4 solution. The C, H, and N were analyzed on a Carlo-Erba 1106 elemental analyzer. The IR spectra was recorded on Jusco 300instrument in KBr pellets.1H ,13Cand the 2DNMR Spectra were recorded on a Bruker (Avance) 300MHz NMR instrument using TMS as internal standard and CDCl3 as solvent Standard Bruker software was used throughout. Chemical shifts are given in parts per million (δ-scale) and the coupling constants are given in hertz. Lc-Mass spectra were recorded on a Bruker Daltonics LC-MS Spectrometer, potantiostat – galvanostatfrom Amel instruments where used for corrosion activity.

AA 929 Unicam Spectrometer was used for FAAS measurements with an air-acetylene flame. A pH meter (Metrohm691 pH Meter) was also used. All extraction experiments were performed by using a mechanical flask agitator in 50 cm3 stoppered glass flasks.

Methods of preparation

Synthesis of Schiff bases of Isatin

Equimolar quantity of isatin (0.005mol) and substituted aromatic diamine (0.0025mol) were added into 30ml of absolute ethanol containing 2-3 drops of glacial acetic acid in 100ml round bottomed flask. The reaction mixture was refluxed for 3-4 hour at the refluxing temperature. The solvent was then distilled off and the product obtained was recrystallized from chloroform to give the Schiff base derivatives [2, 5, 7]. The physical properties ,elemental analysis data and spectral data shown in (Tables I,II,III,IV)

Result and DiscussionChemistry And Charactrazition

The product (I-IX) was formed from the reaction of two molecules of isatin for each mole of diamine. The infrared of products exhibited characteristic peak at1626cm-1 due to ν ( C=N) group and absorption at (1711.5 ) cm-1Due to (C=O) of isatin and no absorption band due to NH2 group. The UV spectra showed λ max at 280-316.1H-NMR for compounds (I-IX)show signal at (7.03-7.67 ppm) due to aromatic proton of isatin and single signal at (11.18 ppm) due to NH of isatin . 1H-NMR for compounds (II,V)show single signal at (2.35,2.32ppm) due to(CH3)group, . 1H-NMR for compounds (VI) show single signal at (11.40ppm) due to (OH)group and 1H-NMR for compound (VII) show single signal at (8.48ppm) due to(NH)group. 1H-NMR for compound (VIII) show single signal at ( 3.93ppm) due to(CH2)group and signal at (7.10, 7.26 ppm) due to (aromatic protons of dip-tolylm ethane),1H-NMR for compound (IX) show signal at(7.3,7.54 ppm) due to aromatic protons of biphenyl.13C-NMR of compounds (I-IX) showed signals at (117.7,146.8,124.5,121.7,131.3ppm) due to aromatic carbons of isatin and signal at (167.5ppm) due to C=O and signal at (163.29) due to (C=N) .13C-NMR spectrum of compound (I) showed signal at (129.6,139.9,158.2,123.3 ppm) due to aromatic carbons of sulphonyl 13C-NMR spectrum of compound (II,V) showed signal at (25.2,19.7 ppm) due to CH3 group , 13C-NMR spectrum of compound (III) showed signal at(127.5,128.8,129.3,130.6) ppm due to aromatic carbons of aromatic ring of 6-phenyl-1,3,5-triazine-2,4-diamine. 13C-NMR spectrum of compound (IV) showed signals at114.6,138.6,161.9 (ppm) due to aromatic carbons of pyridine.13C-NMR spectrum of compound (VI) showed signals at (160.4,169.7, 109.9,181.5) due to aromatic carbons of pyrimidin-4-ol, 13C-NMR spectrum of compound (VII) showed signal at(158ppm) due to 1,2,4-triazole,13C-NMR spectrum of compound (VIII) showed signal at (45.8ppm) due to (CH2) and signals at (140,129.5,122.8 ,150.7 ,122.8,129.5) due to aromatic carbons of Di-p-tolylmethane, compound (IX) showed signals at (134.9,129.2,122.8,152.1) due to Aromatic carbons of (4,4 -dimethylbiphenyl).

Antimicrobial Activity

The antimicrobial activity of both categories of compounds was determined by the disc diffusion method [3, 4]. The in vitro antimicrobial activity was carried out in two gram positive bacteria, and two gram negative bacteria. The gram positive bacteria used were Staphylococcus aureus and Bacillus subtilis, gram negative bacteria used were Escherichia coli and Klebsiella pneumonia.

The compounds were tested at a concentration of 100μg/ml in Dimethylsulfoxide. The zone of inhibition was compared after 24 h of incubation at 37° against Ciprofloxacin (100μg/ml) as standards for comparison of antibacterial activity (table V) In general, all synthesized compounds exhibited good inhibitory activity against tested pathogenic microorganism (S. aureus, B. subtilis, E. coli, K. pneumonia) peculiar against (S. aureus).

NH

O

2

(0.01 mol)NH2-Y-NH2CH3CH2OH

D

Y: , ,

(I,IX)

I

NN

N

II

CH3

NN

N N

,

III IVV VI

CH3

, ,

N

N

OH

NH

N

N

VII VIII

,,

IX

O

S

O

O

NH O

N N

HNO

Y

CH3COOH

Scheme 1 Synthesis of compounds (I-IX)

Citation: Eissa HH (2015) Synthesis, Characterization, Anticorrosion Activities and Antibacterial Activities of New Schiff Bases. BAOJ Chem 1: 001.

BAOJ Chem, an open access journal Volume 1; Issue 1; 001

Table (I) : Physical properties of compounds ( I-IX)

Comp. No. Y M.P

(0C)

Yield

( %)Molecular

WeightMolecular

formulacolor U.V(CHCl3)

λ max (nm)

IS

O

O189 60 508 C28H20N4O4S red 295

IINN

N

CH3

235 30 385 C20H15N7O2 White 298

IIINN

N

182 40 447 C25H17N7O2 white 300

IV

N

291 60 369 C21H15N5O2 Brown 310

VCH3

310< 65 382 C23H18N4O2 red 280

VI

N

N

HO

310< 70 386 C20H14N6O3 White 316

VIINH

N

N

210 75 359 C18H13N7O2 orange 317

VIII 310< 458 C29H22N4O2 White 318

IX 310< 444 C28H20N4O2 orange 319

Page 3 of 9Citation: Eissa HH (2015) Synthesis, Characterization, Anticorrosion Activities and Antibacterial Activities of New Schiff Bases. BAOJ Chem 1: 001.

BAOJ Chem, an open access journal Volume 1; Issue 1; 001

Table (II) FT-IR Spectral data for compounds (I-IX)

Comp. No. Y υ (N–H ) cm-1 υ(C=N) cm-1 uC=O Others

I S

O

O3412.6 1621.3 1724.1

1230.36(asymmetric –SO2-),1155.28

(symmetric-SO2-stretch)

II NN

N

CH3

3432.8 1624.6 1711.5

IIINN

N

3440 1626 1690

IV

N

3431.4 1619.2 1713.4

V

CH3

3431.4 1617.1 1731.8

VI

N

N

HO

3434 1649.9 1725.5 3380.9(OH)

VII

NH

N

N

3451.2 1618.2 1735.6

VIII 3428 1631 1700

IX 3435 1632 1700

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BAOJ Chem, an open access journal Volume 1; Issue 1; 001

Table (III): Depacited Elemental Analysis (C.H.N) of synthesis Compounds

compounds Calc. FoundH% N% C% H% N% C%

I 3.96 11.02 66.13 3.95 11.01 66.14II 3.92 25.44 62.33 3.90 25.43 62.32III 3.83 21.91 67.11 3.82 21.90 67.10IV 4.09 18.96 68.28 4.08 18.95 68.25V 4.74 14.65 72.24 4.72 14.62 72.23VI 3.65 21.75 62.17 3.64 21.50 62.16VII 3.65 27.29 60.17 3.64 27.25 60.16VIII 12.22 4.84 72.97 12.20 4.83 72.96IX 4.54 12.60 75.66 4.52 12.59 75.65

Table (IV) 1H-NMR and 13C-NMR spectral data for some of the prepared compounds.

Compd.No. Compd. Structure 1H-NMR spectra data 13C-NMR spectra data

ISO

ONH O

N N

HNO

7.03,7.27,7.60,7.67(8H,Ar-isatin),7.40,7.97(8H,Ar),11.18(2H

,2NH)

129.6,139.9,158.2,123.3(12C,Ar),117.7,146.8,124.5,121.7,131.3(12C,Ar-isatin)

167.5(2C,2C=O),163.2(2C,C=N)

IINN

N

CH3

NH O

N N

HNO

2.35(s,3H,CH3),7,7.3,7.6,7.7(m,8H,Ar-isa tin),11.18(s,2H,2NH)

25.2(1C,CH3-Ar) 117.7,146.8,121.7,131.3,124.5(12C,Ar-isatin)

,163.29 (2C,2C=N),167.5(2C,2C=O) , 170,178.7(3C,Ar)

III NN

N

NH O

N N

HNO

7,7.3,7.6,7.7(8H,Ar-isatin) ,7.48,7.50,8.36,7.50(5H,Ar),11.18(s,

2H,2NH)

117.7,129.4,124.5,131.3,121.7,148.8(12C,Ar-isatin) ,163.29(2C,2C=N)167.5(2C,2C=O),127.5,128.8,129.3,130.6(6C,Ar),17

0.8,172.9(3c,Ar)

IV N

NH O

N N

HNO

7,7.3,7.6,7.7(8H,Ar-isatin) ,7.4,7.8(3H,Ar-pyridin) ,11.18

(s,2H,2NH)

117.7,129.4,124.5,131.3,121.7,146.8(12C,Ar-isatin) ,114.6,138.6,161.9(5C,Ar-

pyridin) , 163.2 (2C,2C=N) ,167.5(2C,2C=O)

V N

NH O

N N

HNO

CH32.32(s,3H,CH3)7,7.3,7.7(8H,CH3),

,11.18(2H,2NH),7.3,7.7(2H,Ar)

19.7(C,CH3-Ar) 117.7,129.4,124.5,131.3,121.7,146.8(12C,Ar-isatin), 113.8,137.7,124.2,177.1,159.6(5C,Ar-pyridin) ,163.2

(C=N) ,167.5(C=O),

Page 5 of 9Citation: Eissa HH (2015) Synthesis, Characterization, Anticorrosion Activities and Antibacterial Activities of New Schiff Bases. BAOJ Chem 1: 001.

BAOJ Chem, an open access journal Volume 1; Issue 1; 001

VIN

N

NH O

N N

HNO

OH

6.7(1H,Pyridin),7,7.6,7.3,7.7(8H,Ar-isa tin ),11 40 (1H,OH),11.18(2H,2NH)

117.7,129.4,124.5,131.3,121.7,146.8(12C,Ar-isatin),160.4,169.7,109.9,181.5(4C,

Ar-pyrimidin),

163.2 (C=N) ,167.5(C=O)

VII

HN N

N

NH O

N N

HNO

7,7.6,7.3,7.7

(4H,Ar-isatin) ,8.48(1H,NH(1,2,4-TRIA

ZOLE),11.18(2H,2NH –isatin)

117.7,129.4,124.5,131.3,121.7,146.8(12C,Ar-isatin) , 158(2C,Ar-triazole), 163.2

(C=N) ,167.5 (C=O)

VIIINH O

N N

HNO

3.93(s, 2H ,CH2) ,7.10, 7.26(m,8H,Ar-dip-tolyl-

methane) ,7.03, 7.27, 7.67, 7.60(4H ,Ar-isatin) ,11.18

(2H,2NH)

45.8(C,CH2), 117.7,129.4,124.5,131.3,121.7,146.8(12C,Ar-isatin) ,140,129.5,122.8,150.7,122.8,129.5 (12C,Ar-dip-tolyl-

methane), 163.2 (C=N) ,167.5(C=O)

IXNH O

N N

HNO

7.3,7.54(8H,Ar),7.03,7.27,7.67 (8H,Ar-isa tin),11.18(2H,2NH)

117.7,129.4, 124.5,131.3,121.7,146.8(12C,Ar-isatin) , 163.2 (C=N) ,167.5 (C=O),134.9,129.2,

122.8,152.1(12C,4,4’-biphenyl)

Table(V) Antimicrobial activity of Schiff base derivatives

CompoundZone of inhibition (mm)

Gram positive bacteria Gram negative bacteriaS. aureus B. subtilis E. coli K. pneumonia

I 7 7.5 7 7.5II 8 8 6.5 7.5III 8 7.5 7.5 7.5IV 8 7.5 7 7V 7.5 7.5 7.5 7.5VI 9 7 7.5 7VII 8 6 8 9VIII 10 10 9.5 9.5IX 8 9 10 8

* Ciprofloxacin (Stan-dard) 10 10 9.5 9.5

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Table (VI) : Corrosion kinetic parameters of mild steel exposed to 1M H2SO4solution in absence and presence of inhibitors

IE(Using icorr) %Rpbc/(mv.dec -1)ba /(mv.dec -1)icorr/cm1--Ecorr/mvCOMPOUND Name

BLank12.436.38480480blank

77.08116.01918.657.49110460I

63.54106.5117.067.38175459II

85.16330.5411.1710.1970500III

77.08116.01918.657.49110460IV

89.5871.1319.526.28199450V

87.5349.8311.828.1860520VI

63.5495.9525.784.55175418VII

87.50359.3913.727.7960440VIII

79.16221.5814.557.86100510IX

Anticorroision Activity

Electrochemical measurements

Were carried out in conventional three–electrode system in CHI 604 instrument (USA) at 303 K. The working electrode (mild steel) has a geometric area of 1 cm2. The saturated calomel and platinum electrodes were used as reference and auxiliary electrodes. Equation (1) show the calculation of IE from corrosion current : [8, 1, 13].

(Table (VI)) shows the corrosion potential (Ecorr), corrosion current (icorr) and Tafel slopes (ba and bc) values of mild steel in 1M H2SO4 solution in the absence and presence of inhibitor of all the nine compounds at 303K calculated from Schemes (II- IX) from (Table (V)) it is clear that compounds (III,V,VI,VIII) offer maximum inhibition efficiency among the nine compounds Schiff base derivatives and the studied compounds suppress the anodic reaction to greater extent than the cathodic one. This behavior is typical of mixed type inhibitors with anodic predominance .

The difference in the efficiency is referred to the molecular structure effect, which have π-delocalized system of Schiff base derivatives(C=N) and unshared pairs of electrons of N, S and O atoms that may cause the increasing or decreasing of the electron density on center of adsorption and leading to an easier electron transfer from the functional group (C=N-group) to the metal, producing grater coordinate bonding and hence different adsorption and inhibition efficiency.

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BAOJ Chem, an open access journal Volume 1; Issue 1; 001

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