Chapter 2
Page 38
2.1 Literature Survey of Schiff Bases and Metal Complexes
It has vital part in improvement of inorganic chemistry and has taken extensive place
in coordination chemistry, biochemistry and environmental chemistry. Schiff bases
have a chelating structure and are in demand due to their straight forwardness to
synthesize and are moderate electron donors with effortlessly tunable electronic and
steric effects thus being flexible. These types of complexes with heavy metals and
transition are used in organic synthesis, medicine, analytical reagent, and metal ion
catalyst [208-210].
Because of high potential permutations Schiff bases have been broadly studied.
Weight determination, Magnetic susceptibility, elemental analysis, molecular,
conductivity, absorption spectrum and thermal analysis of lots of Schiff bases and
their complexes have been informed. A number of workers have reported that the
quickly developing field of bioinorganic chemistry is centered in the existence of
coordination compounds in the living systems [211,212]. In the 1860s the general
synthesis of Schiff bases and reports of metal complexes of these types of ligands
were former published. [213-215].
In many biochemical reactions Imines play an important role. Because a few of the
enzymes make use of n amine group of an amino acid to react with an ketone or
aldehyde to form an imines’ linkage [216], Where R might be an aromatic group or
aliphatic group.
Schiff bases of aromatic aldehydes, having an effective conjugation system, are more
stable while aliphatic aldehydes are relatively unstable and are readily polymerize.
Condensation of amines with ketones and aldehydes has several applications which
contain detection, preparative use and determination of aldehydes or ketones,
purification of carbonyl or amino compounds, or protection of these groups for the
duration of complex or sensitive reactions.
Chapter 2
Page 39
Because of high synthetic flexibility the chemistry of Schiff base is studied broadly
various medicinal utility and co-ordination ability. These compound Contain >C=N
group and are also known an azomethine or as an imine but are normally known as
SCHIFF BASE to honor Schiff [217].
Werner who organized the subject by put forward in his coordination theory in
1893[218] on the basis of old history which was the invention of [CO(NH3)6]CI3 by
Tassaert in 1798[219]. Werner’s basic thoughts on racemisation, mechanisms of
isomerization and the stereochemistry of metal complexes, etc. stay unchallenged
even today regardless of all the immense developments which have taken places
since his days and through the last five decades in particular, yet to be paid the
initiation of sophisticated physico chemical techniques of high accuracy and
capability [220, 221]. The nature of structure and stereochemistry of metal
complexes, the metal-ligand bond, stabilities and liabilities of them and other
properties have noticeably enhanced our understanding. As the alkali metal
complexes shaped by crown ethers and cryptates [222-225], the metal are now
acknowledged forming moderately stable complexes with special types of ligands
which were previously thought to be non-complex formers.
As per Werner [226] atoms, acquire two types of valency is principal, primary or
auxiliary valency and secondary or residual valency. While usual molecules results
from the satisfaction of primary valencies, use of the secondary valences lead to the
form of coordination compounds [227]. During the last 50 years, a study of the
literature shows that as well examine problems of electronic structure, stabilities of
metal complexes, bonding and stereochemistry of metal complexes and, an
increasing number of studies have been dedicated to mechanisms and dynamics of
reaction of metal complexes[228-233]. The classical application of complex creation
in analysis and other laboratory practices have been refined and sophisticated to such
a degree that it is now likely to monitor concentration of species at amazingly low
level. [234].
Chapter 2
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As per the current theory, even the organ metallic compounds belong to the common
class of coordination compounds, and a host of such compounds of a huge majority
of metal have been synthesized with extensive range of organic substrates. Apart
from their academic implication, these are of vast technological consequence because
of their helpful catalytic properties [235, 236]. furthermore, the application of metal
complexes also have an older history, and lots of complex preparation reactions are
in use since previously for the separation, detection and judgment of metals both in
macro and micro scales. A few Metal complexes might be observed in the photolytic
splitting of water producing hydrogen additional current and somewhat exciting
applications of it. Due to non-availability of remnant fuels this method has immense
potential which might be crucial solution to save the world from a severe crisis in the
future for producing a nonpolluting fuel An additional vital development is the
recognition of the very important role of metal complexes in biological
systems[237,238], Both in biological systems and their applications in the technology
and in laboratory a knowledge of the factor that govern the reactivity and stabilities
of metal complexes could be of vast help in understanding the activities of metal
complexes. It is the information of the environment of the metal-ligand bond which
provides a fundamental basis for accepting the actions of metal complexes. In the
field of therapy there are significant uses of metal complexes and of complex
formers. Dates back to 1917 the gold complexes used in the treatment of tuberculosis
and in the treatment of arthritis [239]. Though numerous important developments
have taken place in last 30 years in the field of application of metal complexes in
medicine and biology [240-242]. The case of metal poisoning in lots of the
complexes formers and complex are familiar to be used as drugs in certain types of
diseases as in addition for metal detoxification [243,244].
In few pages the studies on co-ordination compounds have become incredibly
extensive and it’s not possible to describe. The central metal ion is bounded to
diverse Ligands show signs of diverse characteristics properties in co-ordination
compounds. The characteristics of such compounds are based on nature of the type of
ligands and their structures as well as metal. Metal complexes which having organic
Chapter 2
Page 41
molecule in the physiological systems take part in key role to the formation,
existence growth and maintenance of whole human being and as a result the current
research activity phosphorus, nitrogen, oxygen and sulphur containing organic
molecules are very important components of physiological system and therefore
Complexation studies of organic compounds having these atoms established
particular interest by coordination chemists [245-247].
The chemistry of the metal complexes of Schiff bases having nitrogen and other
donors has been paid considerable awareness in last two decades [248-254]. Schiff
bases recommend a flexible and versatile series of ligands able to bind with a range
of metal ions to provide complexes with appropriate properties for practical and/or
theoretical applications. Seeing as the publication of Schiff base complexes, a huge
number of polydentate Schiff base compounds have been extensively investigated
and structurally characterized. This may be credited to , biological activity, stability
and potential applications in various area such as, electrochemistry, oxidation cataly-
sis etc. The subject of great interest is the study of relationship between the metal
ions and their metal complexes as antibacterial and antitumor agents. More than 25
inorganic compounds being used in therapy as antiviral, anticancer and antibacterial
drugs which field was initiated by the inorganic pharmacology [255-264].
Gheorghe, et al., (2001) had most important focus on twenty new Schiff bases resulting
in the presence of catalytic amounts of sulfuric acid from ortho- hydroxy aldehydes and
hetroaromatic or aromatic amines have been prepared in high yields via condensation in
ethanol. These useful as ligands, azomethines, intermediates in organic synthesis or latent
biologically active substances, have been characterized by IR, 1H and 13C NMR spectra
and elemental analysis.[265]
Chapter 2
Page 43
Iqbal, et al., (2009) had chief focus on neutral complexes of Cu(II),Ni(II), and Co(II)
with a Schiff base resulting from sulfonamide and benzaldehyde have been prepared
and characterized the basis of on UV -VIS, FTIR , atomic absorption spectroscopic
data and molar conductance. Against two bacterial species E.coli these metal complexes
were screened for their antibacterial activity. [266]
Joshi, et al., (2010) had key focus on Schiff base and its metal complexes preparation by
Condensation of p-Chloro benzaldehyde and vanillin with Trimethoprim correspondingly
in methanol. Additional their metal complexes have been prepared by metal salts of Ni
(II), Mn (II), Co (II), and Zn (II) were Characterized by UV, IR, Elemental analysis and 1HNMR spectral data. The Schiff base and its complexes were compared with the
standard antibiotic oflaxocin and their in vitro growth inhibiting activity against different
strains of bacteria viz., gram positive Staphylococcus aureus, Bacillus licheniformis,
Micrococcus lutes and gram negative Escherichia coli. [267]
Joshi, et al., (2011) had main focus on a little of new Schiff bases derived from the
cinnamaldehyde and p-chloro benzaldehyde with aldehydes and amoxicillin trihydrate
and their complexes with bivalent transition metal exe., Co (II), Ni(II), Mn (II) and
Zn(II). They were screened for antibacterial activity against numerous bacterial strains
namely E.coli (-), M.luteus (+), S.areus (+) and B licheniformis(+)(ATCC). The metal
complexes demonstrated improved antibacterial activity evaluate to uncomplexed ligand
[268].
Joshi, et al., (2011) studied on condensation of p-chloro benzaldehyde and
cinnamaldehyde with cephalexin correspondingly in methanol. By copper, nickel, zinc
and manganese the complexes were prepared. Through TLC, IR, UV, 1H NMR, molar
conductance characterization of the components were done. With gram positive and gram
negative bacteria the synthesized compounds were checked for its antibacterial activities.
[269].
Chapter 2
Page 45
Figure 2.3
Khosa, et al., (2011) had main focus on three novel series of biologically active amino
substituted Schiff bases in ethanol with R1N = CHR2 (R1 =4-amino-salicylic acid, 2-
amino-benz thiazole and 4-amino phenol: R2 = benzaldehyde, salicylaldehyde, 2-cholro
benzaldehyde and vanillin). By different physic-chemical techniques the synthesized
compounds were characterized. Using Amoxicillin and Ciprofloxacin as standard drugs
the Compounds showed promising antifungal and antibacterial activities [270].
Figure 2.4
Chapter 2
Page 47
Mashaly, et al., (2004) had focus on a sequence of biologically active mononuclear
complexes of Co (II), Zn (II), Ni (II) and Fe (III) was synthesized. In the presence of
LiOH, the reactions of the Schiff base ligand 1-phenyl-2, 3-dimethyl1-4, salicylalidene
pyrazole-5-one with the previous metals. The binary complexes respond with the mixed
ligand 2-aminopyridine, 8-hydroxyquinoline and oxalic acid to figure the mixed ligand
complexes. All the mixed and binary ligand complexes have octahedral configurations.
Their structures were clarified by, conductance, elemental analysis, IR, magnetic
moments, 1H NMR and TG-DSC measurements [271].
Figure 2.7
Chapter 2
Page 51
Naz, et al., (2009) had discussed on Ni(II),Co(II), and Fe(II) metal complexes of
innovative Schiff bases resulting from amoxicillin with sugers (D-Glucose and D-
mannose) have been prepared and characterized by , electronic absorption, element
analysis, FTIR, and aromatic absorption spectroscopy. Every complexes have superior
biological activities than pure amoxicillin [272].
Figure 2.12
Chapter 2
Page 53
Bayer reported the broad exploration in the field of Schiff bases. Layer reported their
synthesis, chemical and physical properties [273].
A few methods for the preparation of Schiff bases have been described by Dayagi
and Degani [274].
Because of the vital ability and various structure Schiff base feature, wide range of
Schiff base compounds and their metal complexes have studied and synthesized. By
condensing or fusing the synthesis of the Schiff base occurred which is described by
Jura and Scott.
Different infrared spectra of Schiff bases have been considered. The obtained rage of
the IR frequency for the Ar-CH=N-Ar of Schiff base is 1630 to 1615 Cm-1
distinguished by Cloughertyet et al. An absorption band for the alkyl Schiff base
RCH = N-R’ was in range at 1681-16667cm-1 which have been studied by Steele.
Aliyu, et al., had main focused on Schiff base derivatives from a few aliphatic
diamines and 2-hydroxy-1-napthaldehyde has been characterized and synthesized.
Copper complexes were formed from each Schiff base ligands, the elemental
analysis, molar conductance, temperature decomposition, solubility, U.V and IR was
taken. In complex’s elemental analysis the metal ratio to ligand is 1:1 for C, N and H.
Antifungal and anti microbial activities were done. [275]
Babu, et al., (2004) had main focused on synthesis, characterization of novel Schiff base
of Tris (hydroxy methyl) methyl amine-vanillin. The detailed study of polarographic for
the complexes in lead ion is present here. [276]
Bairagi, et al.,(2009) had main focus on various anilines and 4-Chloro-2-oxo-2H-3-
carboxaldehyde in solvent like rectified spirit for yield to a title compounds series viz.,4-
chloro-3-((substituted phenyl imino) methyl)-2H-chromene-2-one. On the spectral data
base IR and 1H NMR the compounds was characterized and estimated for in vitro
Chapter 2
Page 54
activity again to fungi and gram negative bacteria. Most active compound found in MIC
of 15 ug/ml again all organisms tested. [277]
Deshpande, et al.,(2013) had focus on the synthesis of 12 Schiff bases complexes has
been discussed, By Pyridine 2-carboxaldehyde, pyrrole 2-aldehyde with 2-amino-4,6-
dimethyl Benzothiazole condensation Schiff bases are observed, and Mn (II), Ni(II),
Cr(II),Cu(II),Fe(II) and Cu(II) chloride were chosen to synthesized novel metal
complexes. On the basis of mass NMR and IR study the Schiff base and metal complexes
characterized. The Schiff base and its metal complexes were shown antibacterial activity
with a variety of bacteria. [278]
Figure 2.14
Figure 2.15
Chapter 2
Page 55
Dey, et al., (20010) had synthesized a innovative Schiff base which is N-2-[3’-(methoxy
salicylidene imino) benzyl]-3-methyl salicylidene imine (I) through the reaction of 3-
methoxy salicylaldehyde and 2-amino-1-amino benzyl amine with use of ethanol. With
single crystal XRD the molecular structure was defined. [279]
Geronikakai, et al., (2003) had designed various novel thiazolinyl; benzo thiazolyl and
thiazolyl contain Schiff bases. The Schiff base has been reported and performs as
lipoxygenase inhibitors which affect psoriasis or inflammation. The compounds were
defined as reducing activity and as soya beans lipoxygenase inhibitor. By paw oedema
technique was used for check in vivo activity. [280]
Jayabalakrishnan, et al., (2002) had synthesized Schiff bases through condensation by O-
aminophenol and O-amino thiophenol with O-vanillin or salicylaldehyde in attempt to
acquire various ruthenium complexes. [281]
Jayshree et al., (2004) had prepared Schiff bases react various aldehydes with 2-amino-4-
(3-coumarinyl) thiazole. Many of Schiff bases show an anti-inflammatory and analgesic
activity. [282]
Kam, et al., (2001) prepared 1:1 and 1:2 Schiff bases derivatives by O-vanillin and 2,3-
diaminopyridine and with eight metal complexes of them. These ligands and its
coordinated compounds exhibit the antibacterial activity. [283]
Khan, et al., (2002) synthesized the Schiff bases from isatin. The compounds evaluated
analgesic activity. The ligands have less analgesic activity than aspirin comparatively.
[284]
Khan, et al., (2002) Prepared isoniazid Schiff base which is for their anti bacterial activity
use as test organism like Staphylococcus aureus. The inhibition zone was checked by
using standard as amikacin. [285]
Chapter 2
Page 56
Kulkarni, et al., (2012) had studied 15 novel complexes of lanthanides of Schiff base
which are shown, the Schiff bases were synthesized through condensing 2, 5-di hydroxy
acetophenone, pyridine 2-aldehyde with 2 amino 4, 6-dimethyl Benzothiazole, and
lanthanide chlorides were preferred to prepare novel complexes. These metal complexes
were selected for antibacterial activity, antimicrobial activity against E-coli, s-aureus like
bacteria and A-Flavus and A-Niger like antifungal activity. [286]
Mittal, et al., (2009) had synthesized and characterized metal complexes of analytical,
physical and spectral data. The recently prepared metal complexes had a composition
M(LX) 2Y2 where M = Mn (II), Ni (II), Co (II) and Cu (II), LX = bidentate ligand Y = Cl
demonstrated octahedral type geometry, The Schiff bases and its metal complexes was
screen for its antifungal and anti bacterial activity. [287]
Mobinkhaledi, et al., (2010) synthesized few of new Schiff bases with easy and effective
method by reaction between 2- amino benzaldehyde with aromatic aldehydes in organic
solvent with catalytic quantity of M(NO3)2.xH2O at ambient temperature. This little
compensation gives better yields by using catalysis, fast reaction and easy to work up.
[288]
Mohan, et al., focused on thirty novel Schiff bases with ten aromatic aldehydes and 2-
amino-3-(N tolyl carboxamido)-4,5- trimethyle thiophenes. From these some Schiff bases
showed good antibacterial activity. [289]
Naik, et al., (2004) prepared some of Schiff base from heterocyclic compound, through
aldehydes and 2-amino-4-(3-coumarinyl) thiazole and then react compounds with chloro
acetaldehyde. For antibacterial activity they are screened. [290]
Chapter 2
Page 57
Ndahi, et al., (2012) synthesized the Schiff bases with 2,4-di nitro phenyl hydrazine or
anisidine and 4- anisaldehyde by condensation reaction. By electronic spectra elemental
analysis, molar conductance and infrared spectra have been characterized. Against few of
pathogenic bacteria like Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli,
Staphylococcus aureus and salmonellatyphi the compounds were measured in vitro study
for antibacterial activity by agar-well diffusion technique. [291]
Figure 2.16
Chapter 2
Page 58
Paneerselvam, et al., (2005) had synthesized derivative of Schiff bases from 4-(4- amino
phenyl) morpholine and checked antibacterial and also antifungal activity. All
compounds shows good activity. [292]
Patil, et al., (2012) done reaction of aryl aldehyde with primary aromatic amine with
catalytic amount of lemon juice use as natural acid in solvent free condition with good
yield correspondingly. This reaction is eco friendly and very much economic; condition
of the reaction is mild, easy work-up and environment friendly along with great yield of
product. [293]
Prakash, et al., (2011) had focus on Synthesize flexible Schiff base ligands from
condensation of compound containing carbonyl and amino group. The Schiff base and its
metal complexes are vital and use as catalysis, dyes, polymers and pharma and medical
fields. Also they are useful in food industry, in birth control and ass O2 detector. This is
described the use of Schiff base and its metal complexes. [294]
Saxena, et al., (2012) work on the Schiff base ligand was synthesized with 4-amino 5-
mercapto 5-triazole and furfuraldehyde and also characterized. With molar conductance,
IR, 1H NMR elemental analysis, magnetic measurement and by electronic spectral data of
V(III), Ru(III), Ti(III) and Co(III) prepared from the ligand were synthesized and
characterized. By the study these metal complexes octahedral structure assigned. [295]
Sheeja, et al., (2012) synthesized metal complexes of Ni (II), Zn (II), Co(II) and Cu (II)
which was synthesized with tryptophan and 4-pyridine carboxaldehyde. By UV and IR
The complexes are characterized also the study of its DNA cleavage and microbial
activity have been carried out. The ligands and its complexes demonstrated promising
activity again Pseudomonas aeruginosa, Klebseilla pneumonia, Staphylococcus aureus,
Escherichia coli, fungi and Proteus, Aspergillus Niger. [296]
Shetty, et al., (2004) had focus on preparation and evaluation of the antibacterial study of
30 new Schiff bases prepared with 2-amino-3-(N chlorophenyl carboxamido)-4,5-
Chapter 2
Page 59
dimethyl thiophenes. The ligands were prepared through condensation of 10 differ
aldehydes. [297]
Shijun, et al., (2002) had prepared 30 novels hydroxy semicarbazide Schiff bases Ar-CH-
NHCONHOH where Ar = 5-nitro 2-thienyl, CF CH, etc. These are checked against
murine leukemia L1210 cells. By QSAR analysis the pharmacophor which necessary is
NHCONHOH, portability/size of molecule, hydrophobicity and having group which
contain oxygen in the ortho position from there the antitumor activity is significant. [298]
Singh, et al., (2002) synthesized new Schiff base from anisaldehyde, indol
carboxaldehyde, Acetophenone and O vanillin through condense with 4-amino 3-
mercapto 6-methyl 5-oxo 1,2,4-tiazine.The Schiff bases was synthesized for the attempt
to prepare novel complexes by nickel, zinc, cobalt and copper. [299]
Singh, et al., (2003) had prepared ligands derivatives with nucleophillic addition of 2-
pyridine carboxaldehyde, O-vanillin, p-nitro benzaldehyde and O-nitrobenzaldehyde
towards 4-amino 3-ethyl 5-mercapto 5-triazole and 3-ethyl4-amino 5-mercepto 3-mesyl
5-triazole. By copper, nickel, zinc and cobalt bivalent metal complexes were synthesized
through Schiff bases synthesized. [300]
Sun, et al., (2001) prepared 4 Schiff bases from dl- amino acid ands and O-vanillin by
quantum chemical techniques and dynamic analytical techniques. [301]
Suresh, et al., (2011) studied on novel series of Cu(II),Co(II),Zn(II),Ni(II) and Mn (II)
metal complexes which were prepared through new macro cyclic ligand along with 4 N
donor derivatives with O-phenylenediamine and vanillin,4-amino antipyrine. Many of the
instruments analysis such as molar conductance, UV, IR, ESR and NMR, elemental
analysis, TGA spectroscopic techniques were help to identify the chemical structure of
synthesized ligands and its metal complexes. [302]
Chapter 2
Page 60
Suresh, et al., (2004) focused on new bidentate ligands which prepared with vanillin and
4-amino antipyrine to figured stable metal complexes with metal ions like Ni(II), Cr(III),
Mn(II), Cd(II), Cu(II) and Zn(II). Structure of them was identified by IR, NMR, ESR,
TGA, electronic spectroscopy and elemental analysis. [303]
Thorat, et al., had work on nitrated vanillin through use process of literature 3-methoxy 5
4-hyroxy 5-nitrobenzaldehyde. By the well known literature process of Vogel 5th addition
for organic chemistry practical the Schiff based were prepared with use of halogen
substituted anilines. Because of the reactivity of nitro vanillin to amines the formation of
4-{(E) [(4- aryl) imines] methyl} 2-methoxy 6-nitrophenol and study for the fluorescence
was occurred. [304]
Vaghashiya, et al., (2004) derived Schiff bases from vanillin and 4-1-phenyl 2,3-
dimethyl-4-aminopyrazol-5-one which shown ability of antibacterial agents in front of a
few gram negative and positive strains of bacteria. The activity was done in two solvents
like Dimethyl formamide and Dimethyl sulphoxide which are very polar. Schiff base
synthesized having vanillin with sulphamethoxazole and 2,4-dimethylaniline in DMSO
efficiently inhibit the bacteria and shows potential antimicrobial agents. [305]
Venugopal, et al.,(2004) prepared bromo thiazolyl amino coumarin Schiff bases from
different aromatic aldehydes with 2-amino 4-(6-bromo-3-coumarinyl) thiazole. The
ligands show anti inflammatory and analgesic activities. With presence of some
functional group few compound shown exciting biological activities. [306]
Vinci, et al., (2003) concentrated to prepare 3 novel series from thiazole and benzo (d)
isothiazole ligands which shown the anticancer and antiviral which is not definitely cure
presently. The compounds illustrated noticeable cytotoxicity in front of CD4+
lymphocytes (MT 4) which used to carry the growth of HIV-1. These compounds inhibits
leukemia cells growth and from them one compound exhibit anti proliferative activity
that shown by the results. [307]
Chapter 2
Page 61
Wang, et al., (2002) prepared 12 novel Schiff bases having 5-amino 1H 1, 2, 3, 4-
tetrazolyl. The Schiff bases transformed in α–(5-tetrazolyl) amino alkyl phophonate
through treat it with (EtO)2 P O H outcome of the biological study described few of
compounds have noticeable plant expansion variable activities. The majority of Schiff
bases which active were synthesized from 3-formyl indole and Chlorobenzaldehyde.
[308]
Zakrzewski, et al; (2003) had prepared the derivatives of N-benzylidene -4(4,5 –dipheny1
1H- imidazole -2y1) anilines and invent the fungal activity in front of six microorganism.
[309]
Zhu, et al., (2003) synthesized Schiff base from salicylaldehyde, O-vanillin with 5-
Mercapto 2-amino, 1, 3, 4-thiadiazole and the molybdenum complexes of it. Their result
on the continued existence cell ratio of spout in beans has been examined. [310]
Bharte, et al., (2010) searched on drugs compatibility signifies a vital stage in the
formulation phase of growth of every dosage form. The probable chemical and physical
relations among excipients and drug may influence on chemical environment, the bio
avaibility and stability of drug and, their therapeutic safety and ability. At the time when
the pharmaceutical system’s of solid phase reaction comes in understanding, the essential
steps could be carried out to concern the reactivity and get better the stability of product
and drug substance both. [311]
Iqbal, et al., (2005) has been studied on Co(II) and Zn(II) Schiff base complexes of
cephalexin and amoxicillin with pyridoxal, salicylaldehyde were synthesized and
characterized TGA and spectral and magnetic data. Above every complex shows
coordination with the six molecules which includes two molecules of water. The Zinc
complexes show octahedral geometry. The compounds are giving promising activity
towards bacterial study. Activity of drug taken for Schiff base synthesis is negligible than
all synthesized complexes. [312]
Chapter 2
Page 63
Chandramohan, et al., (2012) studies the condensation reaction of amine with aldehydes.
The purpose of the study is to condense 3 aromatic aldehydes like 4-hydroxy
benzaldehyde, ethyl vanillin and vanillin with Trans amino cyclohexanol to prepared
Schiff bases. Objective of the work is prepared Schiff based. Objective of the work is
prepared Schiff base from allyl bromide and epichlorohydrin by O- alkylation and it was
characterized by IR and 1 H NMR. [313]
Chatterjee, et al., (1990) prepared Schiff base ligands through condensation of 4-phenyl
Thiosemicarbazide and 2-furfuraldehyde or vanillin. With the reaction of Schiff base and
metal salt obtained ML2HO.M coordinate by thiol’s S and azomethines N. By the basis
of different analytical techniques the octahedral structure were planned. [314]
Nicolae, et al., (1990) studied Schiff bases through the reaction of 5- formyl vanillin,
with aromatic 3-amines such as aminopyridine, un substituted anilines and 1 or 2
naphthylamine. More than 80% yield obtained. [315]
Hiroshi, et al., (1991) synthesized numerous Schiff bases of cumin aldehyde,
benzaldehyde, perillaldehyde and hydroxyaniline, aniline with vanillin, and N-
acylated amino acid and D-glucosamine and derivative via theronine, serine and
organic acids like camminic acid, perillic acid, phenyl acetic acid, ferulic acid,
vanillic acid and trans-cinnamic acid is test less, nearly everyone along with the
unprotected C-terminus given a sour taste and with the protected C-terminus contain
a bitter taste. [316]
Oza, et al., (1998) prepared 30 new thiazolidinone compounds through cyclo
condensation with thioglycollic acid and 2,4,6-thiolactic acid were potent anti
tubercular agents. Against tuberculosis like mycobacterium the synthesized
compounds showed anti-tubercular activity. [317]
Zhou, et al., (1999) studied many of Schiff bases in the lake of solvents. The
procedure shows the mixing of amine such as aniline p-phenylenediamine, 4 amino
Chapter 2
Page 64
antipyrine, p-chloro aniline, semicarbazide HCl and p-methyl aniline with aromatic
aldehyde such as o, m and p-hydroxy benzaldehyde, o, m and p- nitrobenzaldehyde
and p-methoxy benzaldehyde. Acid catalysis such as phenolic acid, sulphonic acid
and phenolic acid was use in catalytic amount. [318]
Rathod, et al., (2000) condensed 2-furfuraldehyde and in different way substituted
benzaldehyde with 2-amino 4-methyl Benzothiazole, 2-amino Benzothiazole,2-
amino 6-methyl benzaldehyde, and 2- amino 4-phenyl thiazole and prepared Schiff
bases. Against gram negative and gram positive these compound gives good
antibacterial activity. [319]
Yuan, et al., (2000) prepared 8 novel Schiff bases from substituted benzaldehyde and
5-amino triazole-3-carboxylates which having 1H Et 1, 2, 4-triazole-3-carboxylate
[320]
Murthi, et al., (2000) have studied Schiff base by benzene as a solvent, o-toluidine/p-
toluidine, aniline with o-vanillin. The ru(III) complexes of these Schiff bases were
prepared and studied against Aspergillus niger pathogenic fungi and fusarium sp.
[321]
Wang, et al., (2000) studied on condensation of o-vanillin and DL-alanyl DL-alanine.
The synthesis and characterization of the cobalt, nickel, copper and zinc complexes
were carried out. [322]
Gong, et al., (2000) had synthesized 5 different Schiff bases by substituted
benzaldehyde and 4-amino antipyrine. The Schiff bases show 16 to 320 times more
fluorescence intensity than 4-amino antipyrine. [323]
Wu, et al., (2000) done reaction of vanillin aldehyde and chitosan in water and
prepared Schiff base. The reaction was dependent on reaction’s temperature, time
and concentration. [324]
Chapter 2
Page 65
Yuli, et al., (2000) prepared bis phophonate which was phenol substituted with
substituted benzaldehyde and nitro aniline through reduction and condensation and
its antitumor activity were checked. The antitumor activity was depended on the
place of phenolic hydroxyl group which was next of double bond. This Schiff base
was shows more effectiveness than other. [325]
Shakih, et al., (2001) have prepared Schiff bases with Benzothiazole having
substitution in 2nd position. The compounds were prepared and checked antifungal
and antibacterial activities. [326]
Mohan, et al., (2002) prepared 30 Schiff bases with 10 substituted aromatic
aldehydes and 2 amino (3-N tolyl carboxamido) 4,5-tromethylene thiophenes. From
that few Schiff bases showed nice antibacterial activity. [327]
Sleema et al., (2002) et al., have done condensation between L-histidine and o-
vanillin and prepared Schiff bases under reflux condition. The complexes of the
compounds prepared by Co, NI, Cu and iron and studied of X-ray diffraction [328]
Yanhong, et al., (2003) studied on amino acids and o-vanillin Schiff bases and their
metal complexes which having inhibit ability. [329]
N. K. Chaudhary., (2013) synthesized novel ligands with pyrrole 2-carboxaldehyde
and Amoxicillin trihydrate under reflux condition with use of Aq. Methanol and
catalytic amount of acid. The metal complexes prepared with copper, zinc and cobalt
chloride and characterized by 1H NMR, IR, elemental analysis and mass. The Schiff
bases and their metal complexes showed antibacterial activity in front of bacteria like
B. subtilis, S. aureus and E. coli, where amoxicillin trihydrate used and the inhibition
zone was measuring in diameters. Results shown the metal complexes give good
activity than ligand and Amoxicillin trihydrate. [330]
Chapter 2
Page 67
Figure 2.21
Taghreed, et al., studied Novel ligand (E)-6-{2-[4-(Dimethyl amino) benzylidene
amino]-2-(4-hydroxy phenyl) acetamido}-3,3-dimethyl-7-oxo-4-thia-1-aza bicyclo
[3,2,0] heptanes 2-caboxycillic acid prepared with condense 4dimethyl amino
benzaldehyde with amoxicillin in methanol as solvent. As per figure the mixed
polydentate legend’s complexes were found with 1:2:1 mole ratio. The formula of
resultant complexes is ML(NA)2 Cl. Whereas M is Copper, Nickel, Zinc and Iron
while A is nicotinamide.
Chapter 2
Page 68
Figure 2.22
The Schiff base was characterized by using elemental analysis, UV, IR, and 1H
NMR while the metal complexes were characterized by UV, IR, atomic absorption
spectroscopy, magnetic susceptibility, chloride contains by conductance. In Dimethyl
sulphoxide all metal complexes were non electrolytes. For every metal complexes
octahedral geometry has been obtained. The ligands shown as tridentate and for the
coordination enolic form is suggested. Bacterial activities of the Schiff base ligand
and its complexes have been determined. [331]
Chapter 2
Page 69
Figure 2.23
Srivastava et al., has prepared novel, quick, component, clear, environment friendly
Schiff base and its complexes interestingly. The Schiff bases prepared by
sulphamethoxazole, Amoxicillin, Trimethoprim and Cephalexin with pyridoxal and
its metal complexes were prepared by Zn (II), using catalytic amount of alkali and
obtained good yield in microwave synthesis. This method gives benefits like
environmentally, small time for reaction, small time for the reaction, easy for work
up, safe and provides nice yield. Comparison of conventional method and
microwaves method for the time and yield were studied. The characterization was
done by TGA, Spectroscopic and magnetic study, micro analytical techniques. All
synthesized ligands were found bidentate while complexes showed coordination with
six molecules. Complexes are more stable in air and colored. Every compound
Chapter 2
Page 70
shown antibacterial activities which is greater in metal than ligands then drug choose.
[332]
Figure 2.24
Figure 2.25
Chapter 2
Page 71
Malik, et al., Synthesize and characterize Schiff bases and its metal complexes
prepared from diuretic drug xipamide. The condensation of salicylaldehyde and
xipamide was taken in 1:1 ratio for synthesis of bidentate Schiff base. By this ligand
and metal complexes of Zn (II), VO (IV) and Hg (II) were synthesized.
Characterization of this compound was done with IR, mass, elemental analysis,
molar conductance, particle size and by magnetic susceptibility. Elemental analysis
indicates the ratio of the metal complexes and ligand is 1:2. Molar conductance
suggest all complexes are non electrolytic. IR proposed the coordination behavior
among metal ion and ligand by the deprotonation of phenolic oxygen. The geometry
of the VO (IV) complexes is square pyramidal and Zn (II), Hg (II) is tetrahedral
which is proposed by the spectral study of the metal complexes. The Schiff bases and
metal complexes showed antifungal activity and VO (IV) and Hg (II) complexes
showed diuretic activity also. [333]
Figure 2.26
Chapter 2
Page 72
Figure 2.27
By the review of literature, it appears that Schiff bases and metals elements can be
play a vital role in enhancing the efficiency of a drug molecule and or decrease toxic
effects. Therefore, Schiff bases and the metals elements should be measured in drug
design studies.
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