Syntheses, structural characterization, and thermal properties of new 1,2,3,4-tetrahydroquinazoline ligands and their Co(III) complexes

Article abstract of DOI:10.1080/15533174.2013.783870

In this study, new heterocyclic ligands, 2-(3-chloro-phenyl)-1,2,3,4- tetrahydro-quinazoline-2-carbaldehyde oxime,(HL¹) and 2-(3-bromo-phenyl)-1,2,3,4-tetrahydro-quinazoline-2-carbaldehy- de oxime,(HL²), and Co(III) complexes of their open-chain tautomer,(HL¹′ and HL²′), containing oxime, imine, and amine donor groups resulting from the reactions with Co(II) ion have been synthesized and characterized by spectral methods, elemental analysis, magnetic susceptibility, and thermal analysis (TG, DTG, and DTA) techniques. The obtained results show that the ligands undergo a ring-opening reaction upon complexation with Co(III) ion. The analyses confirmed the following molecular formulae: [Co(L¹′)2]Cl.H2O and [Co(L²′)2]Cl. H2O.

Full text of DOI:10.1080/15533174.2013.783870

This article was downloaded by: [Moskow State Univ Bibliote]
On: 13 February 2014, At: 07:59
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Synthesis and Reactivity in Inorganic, Metal-Organic,
and Nano-Metal Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsrt20
Syntheses, Structural Characterization, and Thermal
Properties of New 1,2,3,4-Tetrahydroquinazoline
Ligands and Their Co(III) Complexes
H. Mutlu Gençkal a , N. Pazarli a & G. Irez a
a Department of Chemistry, Faculty of Arts and Sciences , Uludağ University , Bursa , Turkey
Accepted author version posted online: 06 Nov 2013.Published online: 16 Dec 2013.
To cite this article: H. Mutlu Gençkal , N. Pazarli & G. Irez (2014) Syntheses, Structural Characterization, and Thermal
Properties of New 1,2,3,4-Tetrahydroquinazoline Ligands and Their Co(III) Complexes, Synthesis and Reactivity in Inorganic,
Metal-Organic, and Nano-Metal Chemistry, 44:5, 627-633, DOI: 10.1080/15533174.2013.783870
To link to this article: http://dx.doi.org/10.1080/15533174.2013.783870
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 44:627–633, 2014
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2013.783870
Syntheses, Structural Characterization, and Thermal
Properties of New 1,2,3,4-Tetrahydroquinazoline
Ligands and Their Co(III) Complexes
H. Mutlu Genc¸kal, N. Pazarli, and G. Irez
˘
Department of Chemistry, Faculty of Arts and Sciences, Uludag University, Bursa, Turkey
oxime is a synthesis of a imine oxime from carbonyl oxime
and 2-aminobenzylamine;[16–19] there is a ring-chain tau-
tomeric equilibrium between the tetrahydroquinazoline and the
imines.[14,20–22] According to Garc´ıa-Deibe and co-workers, the
tetrahydroquinazoline compound is the most stable form of the
two tautomers, and the ring-chain tautomerism of a 2-aryl-
1,2,3,4-tetrahydroquinazoline which can be exploit to induce
reversible changes in the aminal–imine equilibrium, as desired,
by coordination of a suitable metal ion.[14]
In earlier articles, we described the synthesis and character-
ization of the 1,2,3,4-tetrahydroquinazoline oximes and their
complexes.[17–19] In this work, we have expanded the synthesis
and characterization studies of 1,2,3,4-tetrahydroquinazoline
oximes and their complexes. New heterocyclic ligands, 2-(3-
chloro-phenyl)-1,2,3,4-tetrahydro-quinazoline-2–carbaldehyde
oxime,(HL1) and 2-(3-bromo-phenyl)-1,2,3,4-tetrahydro-
quinazoline-2-carbaldehyde oxime,(HL2), and complexes of
their open-chain tautomer, (HL1ꢁ and HL2ꢁ), with Co(III)
ion were synthesized and characterized by spectral methods,
elemental analysis, magnetic susceptibility, and thermal
analyses.
In this study, new heterocyclic ligands, 2-(3-chloro-phenyl)-
1,2,3,4-tetrahydro-quinazoline-2-carbaldehyde oxime,(HL1) and
2-(3-bromo-phenyl)-1,2,3,4-tetrahydro-quinazoline-2-carbaldehy-
de oxime,(HL2), and Co(III) complexes of their open-chain tau-
tomer,(HL1ꢀ and HL2ꢀ), containing oxime, imine, and amine donor
groups resulting from the reactions with Co(II) ion have been
synthesized and characterized by spectral methods, elemental
analysis, magnetic susceptibility, and thermal analysis (TG, DTG,
and DTA) techniques. The obtained results show that the ligands
undergo a ring-opening reaction upon complexation with Co(III)
ion. The analyses confirmed the following molecular formulae:
[Co(L1ꢀ)2]Cl.H2O and [Co(L2ꢀ)2]Cl.H2O.
Keywords Amine−imine−oxime, Co(III) complex, 2-(3-bromo-
phenyl)-1,2,3,4-tetrahydro-quinazoline-2-carbaldehyde
oxime,
2-(3-chloro-phenyl)-1,2,3,4-tetrahydro-
quinazoline-2-carbaldehyde oxime
INTRODUCTION
Quinazoline derivatives have drawn much attention owing
to their various pharmacological properties. In the literature,
there are many studies relating to synthesis and pharmacologi-
cal properties of quinazoline derivatives.[1–4] However, there are
very few studies in the literature relating to coordination com-
pounds of quinazoline derivatives.[5–14] In one of these studies,
a new fluorescent chemosensor for sensing Co(II) using di(2-
picolyl)amino as a recognition group and quinazoline as a re-
porting group has been synthesized and characterized by Luo
and co-workers.[15]
EXPERIMENTAL
Materials and Measurements
All chemicals and solvents were purchased from Merck,
Aldrich, or Lachema and were used without further purifica-
tion.
The 1H NMR and 13C NMR solution spectra were recorded
at 25◦C on a Varian Mercury Plus 400 MHz spectrometer, utiliz-
ing deuterated dimethylsulfoxide (DMSO-d6) as a solvent. FT-
IR spectra were recorded in the 4000–400 cm−1 region with a
Thermo-Nicolet 6700 Fourier-Transform Infrared Spectropho-
tometer by using KBr pellets. Thermal analysis curves (TG,
DTG, and DTA) were obtained using a Seiko Exstar 6200 ther-
mal analyzer in a dynamic dry air atmosphere at a heating rate
of 10◦C min−1 in the temperature range of 25 to 950◦C using
platinum crucibles. C, H, and N microanalyses and mass spectra
were carried out at the Technical and Scientific Research Coun-
cil of Turkey, TUBITAK Bursa Test and Analysis Laboratory.
1,2,3,4-Tetrahydroquinazoline oximes which are quinazoline
derivatives, are composed of two fused six-membered simple
rings, a benzene ring and a hexahydropyrimidine ring, and an
oxime group. The formation of 1,2,3,4-tetrahydroquinazoline
Received 22 February 2013; accepted 5 March 2013.
This work was supported by the Research Foundation of Uludag˘
University (Project No. 2011/72)
Address correspondence to Dr. Hasene Mutlu Genc¸kal, Department
of Chemistry, Faculty of Arts and Sciences, Uludag˘ University, 16059
Bursa, Turkey. E-mail: hasenem@uludag.edu.tr
627

628
H. M. GENC¸ KAL ET AL.
X
X
HN1
H2N
O
2
3
N
H
+
-H2O
H2N
H
N
H
N
OH
OH
HLn
carbonyl oxime
2-ABA
X=Cl for 3-ClINAP and n:1
or Br for 3-BrINAP and n:2
SCH. 1. Synthesis of the HLn.
Magnetic susceptibility measurements were performed at room was filtered, washed with cold ethanol and finally dried on air
temperature with a Sherwood Scientific MK1 model Magnetic (Scheme 1).
Susceptibility Balance.
2-(3-Chloro-Phenyl)-1,2,3,4-Tetrahydro-Quinazoline-2-
Carbaldehyde Oxime, (HL1). Yield: 0.87 g, 60.4% (white
crystals). m.p.: 158◦C (DTAmax, decomposition point). Anal.
Calcd. for C15H14N3OCl (287.75 g mol−1) (%): C, 62.61; H,
4.90; N, 14.60. Found: C, 62.18; H, 4.57; N, 14.60. FT-IR (KBr
pellet, ν cm−1): 3406, 3263 (s, sh, N H); 2963 (H C N);
2764 (b, N····H O ); 1607 (sh, C Noxime); 944 (s, sh, N O).
1H NMR (DMSO-d6, δ ppm J Hz): 10.94 (s, OH, 1H); 7.58
Preparation of the ␣-Carbonyl Oximes
α-Carbonyl oximes were prepared according to a literature
method[23] with little modification. Nitrosation of 1-(3-chloro-
phenyl)-ethanone or 1-(3-bromo-phenyl)-ethanone with butyl
nitrite afforded the corresponding α-carbonyl oximes. Struc-
tures of the α-carbonyl oximes were inferred from its FT-IR and
NMR spectral data.
(t, J = 1.6, Haromatic, 1H); 7.52 (dt, J = 8.0; 1.2, Haromatic
,
(3-Chloro-Phenyl)-Oxo-Acetaldehyde Oxime, (3-ClINAP).
FT-IR (KBr pellet, ν cm−1): 3244 (s, O H); 2985 (w, H C N);
1628 (s, sh, C-O); 1573 (sh, C Noxime); 1003 (s, sh, N O).
1H NMR (DMSO-d6, δ ppm J Hz): 12.85 (s, OH, 1H); 7.99 (s,
HC N, 1H); 7.97 (s, Haromatic, 1H), 7.89–7.86 (m, Haromatic, 1H),
1H); 7.44 (s, HC N, 1H); 7.35 (t, J = 7.8, Haromatic, 1H);
7.31–7.28 (m, Haromatic, 1H); 6.92 (t, J = 7.6, Haromatic, 1H);
6.73 (d, J = 7.8, Haromatic, 2H); 6.78 (s, N1H, 1H); 6.47 (dt, J
= 7.4, 1.2, Haromatic, 1H); 3.70 (dd, J = 16.8, 5.6, CH2 N,
1H); 3.46–3.40 (m, CH2 N, 1H); 3.31–3.24 (m, N3H, 1H).
13C NMR (DMSO-d6, δ ppm): 152.44 (C Noxime); 146.53,
143.04, 133.22, 130.42, 127.86, 127.67, 127.23, 126.61,
125.97, 120.29, 116.58, 114.75 (Caromatic); 70.93 (Ph>C<);
41.93 ( CH2 N). m/z: 287.6 [HL1]+.
7.72–7.70 (m, Haromatic, 1H), 7.55 (t, J = 8, Haromatic, 1H). 13
C
NMR (DMSO-d6, δ ppm): 188.40 (C O); 148.27 (C Noxime);
138.31, 133.51, 133.21, 130.87, 129.86, 128.61 (Caromatic).
(3-Bromo-Phenyl)-Oxo-Acetaldehyde Oxime, (3-BrINAP).
FT-IR (KBr pellet, ν cm−1): 3253 (s, O H); 3003 (w, H C N);
1642 (s, sh, C O); 1565 (sh, C Noxime); 998 (s, sh, N O).
1H NMR (DMSO-d6, δ ppm J Hz): 12.84 (s, OH, 1H); 7.98 (s,
HC N, 1H); 8.10 (s, Haromatic, 1H), 7.92–7.90 (m, Haromatic, 1H),
2-(3-Bromo-Phenyl)-1,2,3,4-Tetrahydro-Quinazoline-2-
Carbaldehyde oxime, (HL2). Yield: 0.98 g, 59.0% (white
crystals). m.p.: 159◦C (DTAmax, decomposition point). Anal.
Calcd. for C15H14N3OBr (332.20 g mol−1) (%): C, 54.23; H,
4.25; N, 12.65. Found: C, 53.95; H, 3.84; N, 12.31. FT-IR (KBr
pellet, ν cm−1): 3408, 3264 (s, sh, N H); 2962 (H C N);
2765 (b, N····H O ); 1606 (sh, C Noxime); 943 (s, sh, N O).
1H NMR (DMSO-d6, δ ppm, J Hz): 10.95 (s, OH, 1H); 7.72
(t, J = 1.6, Haromatic, 1H); 7.56 (d, J = 1.6, Haromatic, 1H);
7.44 (s, HC N, 1H); 7.42 (d, J = 3.2, Haromatic, 1H); 7.29 (t,
J = 7.8, Haromatic, 1H); 6.92 (t, J = 7.8, Haromatic, 1H); 6.80
(s, N1H, 1H); 6.73 (t, J = 8, Haromatic, 2H); 6.46 (dt, J = 7.2,
1.2, Haromatic, 1H); 3.70 (dd, J = 16.8, 5.6, CH2 N, 1H);
3.46–3.40 (m, CH2 N, 1H); 3.29–3.25 (m, N3H, 1H). 13C
NMR (DMSO-d6, δ ppm): 152.47 (C Noxime); 146.76, 143.02,
130.73, 130.55, 127.24, 127.00, 125.97, 121.89, 120.28,
7.85–7.82 (m, Haromatic, 1H), 7.48 (t, J = 8, Haromatic, 1H). 13
C
NMR (DMSO-d6, δ ppm): 188.33 (C O); 148.29 (C Noxime);
138.51, 136.09, 132.73, 131.11, 128.96, 121.93 (Caromatic).
Preparation of the Ligands
HL1 and HL2 were prepared by the usual condensa-
tion method. A solution of 2-aminobenzylamine (2-ABA)
(5.00 mmol, 0.61 g) in 5 mL of absolute ethanol was added
dropwise to a solution of 3-ClINAP (5.00 mmol, 0.92 g) or 3-
BrINAP (5.00 mmol, 1.15 g) in 15 mL of absolute ethanol. The
reaction mixture was stirred for 2 h at room temperature and
left for a few days at room temperature. The reaction product

NEW TETRAHYDROQUINAZOLINES AND CO(III) COMPLEXES
629
X
X
1
H2N
NH2
1
HN
3
N
air
Co
N
X
Cl.H2O
N
C2H5OH
2
2
3
+ CoCl2.H2O
N
H
N
O
2
H
H
N
O
H
OH
X: Cl for HL1, Br for HL2
SCH. 2. Synthesis of the Co(III) complexes.
116.57, 114.74 (Caromatic); 70.89 (Ph>C<); 41.92 ( CH2 N). J = 14.4, CH2, 2H); 4.71 (d, J = 14.4, CH2, 2H). 13C NMR
m/z: 331.6 [HL2]+.
(DMSO-d6, δ ppm): 173.03 (Ph C N); 139.50 (H Cꢁ N);
139.00–122.46 (Caromatic); 53.80 (CH2). m/z: 721.2 [Co(L2 )2]+.
μeff: diamagnetic.
General Procedure for Preparation of the Complexes
A solution of CoCl2·6H2O (0.75 mmol, 0.178 g) in ethanol
(5 mL) was added dropwise while stirring at room temperature
to a solution of HLn (1.50 mmol, 0.432 g for HL1 and 0.498 g for
HL2) in ethanol (30 mL). Air oxidation was achieved by stirring
vigorously in air for 5 h. After 5 h, the precipitated orange-
colored compound was filtered, washed with cold ethanol sev-
eral times, and dried on air (Scheme 2).
RESULTS AND DISCUSSION
The ligands HL1 and HL2 were synthesized by the condensa-
tion of 2-ABA with 3-ClINAP or 3-BrINAP, respectively. The
addition of cobalt(II) chloride solution prepared in ethanol to an
alcoholic solution of the ligands gave orange-colored complexes
(Scheme 2). They were determined that cobalt(II) is becoming
oxidized to cobalt(III) in the complexes. The physicochemical
and spectral data of the ligands and the complexes of their imine
tautomer are given in Experimental Section.
Bis{(2-Amino-Benzylimino)-(3-Chloro-Phenyl)-Acetaldeꢁhy
de Oximato}Cobalt(III) Chloride Monohidrate, [Co(L1 )2]
Cl·H2O, (1). Yield: 0.27 g, 52.4%. m.p.: 217◦C (DTAmax
,
decomposition point). Anal. Calcd. for C30H28N6O3Cl3Co
(686.52 g mol−1) (%): C, 52.33; H, 4.10; N, 12.30. Found: C,
52.61; H, 3.67; N, 12.13. FT-IR (KBr pellet, ν cm−1): 3431 (b,
H2O); 3236, 3199 (sh, N H); 1618 (sh, C Nimine); 1566 (sh,
Elemental Analyses and Magnetic Susceptibility
The C, H, and N contents (both theoretically calculated val-
ues and actual values) are in reasonably good agreement with
the proposed formulae. The magnetic susceptibility measure-
ment of the cobalt(III) complexes reveal that the compounds are
diamagnetic, confirming the oxidation of cobalt(II) to cobalt(III)
and corresponding to low spin d6 system for Co(III) which sug-
gest octahedral geometry.[17–19]
1
C Noxime); 1041 (s, sh, N O). H NMR (DMSO-d6, δ ppm,
J Hz): 7.74–7.46 (m, Haromatic, 6H and NH2, 4H); 7.21–7.17
(m, CHaromatic, 8H); 6.92 (s, H C N, 2H); 6.68 (d, J = 11.6,
Haromatic, 2H); 4.87 (d, J = 14, CH2, 2H); 4.71 (d, J = 14.4,
CH2, 2H). 13C NMR (DMSO-d6, δ ppm): 173.09 (Ph C N);
139.46 (H C Nꢁ); 139.00–123.04 (Caromatic); 53.80 (CH2).
m/z: 632.3 [Co(L1 )2]+. μeff: diamagnetic.
Mass Spectra
Bis{(2-Amino-Benzylimino)-(3-Bromo-Phenyl)-Acetaldehyde
In the free ligands, the molecular ion peaks have been ob-
served at m/z 287.6 for HL1 and at m/z 331.6 for HL2. In the
mass spectra of the cobalt(III) complexes, the strong peaks at
m/z 632.3 and at m/z 721.2 can be related to the [Co(L1ꢁ)2]+ and
[Co(L2ꢁ)2]+ ions, respectively.
ꢁ
Oximato}Cobalt(III) Chloride Monohidrate, [Co(L2 )2
]Cl·H2O, (2). Yield: 0.42 g, 72.3%. m.p.: 214◦C (DTAmax
,
decomposition point). Anal. Calcd. for C30H28N6O3Br2ClCo
(774.79 g mol−1) (%): C, 46.51; H, 3.64; N, 10.85. Found: C,
46.80; H, 3.33; N, 10.59. FT-IR (KBr pellet, ν cm−1): 3454
(b, H2O); 3233, 3199 (sh, N H); 1613 (sh, C Nimine); 1559
IR Spectra
1
(sh, C Noxime); 1022 (s, sh, N O). H NMR (DMSO-d6, δ
The FT-IR spectra of the solid form of HLn indicate that
ppm, J Hz): 7.85 (d, J = 7.2, Haromatic, 2H); 7.76–7.38 (m, the ligands are in ring form. There are two main features in
Haromatic, 4H and NH2, 4H); 7.29–7.11 (m, Haromatic, 8H); 6.91 the FT-IR spectra of the new ligands, HL1 and HL2. The first one
(s, H C N, 2H); 6.66 (d, J = 11.2, Haromatic, 2H); 4.86 (d, is the disappearance of the characteristic carbonyl group of the

630
H. M. GENC¸ KAL ET AL.
The 13C NMR spectra of the α-carbonyl oximes showed a
signal for the carbon atom of the carbonyl group at δ 188.40 ppm
for 3-ClINAP and δ 188.33 ppm for 3-BrINAP while this was
not observed in the 13C NMR spectra of the HL1 and HL2. In
addition, the HL1 and HL2 ligands showed a signal correspond-
ing to the quaternary carbon atom of the heterocyclic ring at δ
70.93 ppm and δ 70.89 ppm, respectively, suggesting that the
1,2,3,4-tetrahydroquinazoline ring is formed.[16–19] The carbon
atom of the oxime group was observed at δ 152.44 ppm for HL1
and δ 152.47 ppm for HL2. The 13C NMR spectra of the lig-
ands displayed a range of aromatic carbon resonances between
δ 146.76 and 114.74 ppm. As for the carbon atom of CH2
group in HL1 and HL2, it was resonated at δ 41.93 ppm and δ
41.92 ppm, respectively.
α-carbonyl oximes, while the second feature is the appearance
of the band at ca. 1302 cm−1 for HL1 and HL2, which is assigned
to stretching vibration of the C N group and confirming the
condensation reactions. The FT-IR spectra of the ligands exhib-
ited fairly strong bands at 3408–3263 cm−1 attributable to the
ν(N H) vibrations. The oxime ( OH) stretching vibration of
the ligands appeared as a broad peak maximum at 2764 cm−1
for HL1 and 2765 cm−1 for HL2, assigned to the intramolec-
ular hydrogen bonding vibration (N····H O ). In the FT-IR
spectra of the ligands, ν(H C N), ν(C Noxime), and ν(N O)
characteristic stretching vibration bands were observed at 2963,
1607, and 944 cm−1 for HL1 and at 2962, 1606, and 943 cm−1
for HL2. These values are in accord with those of previously
reported 1,2,3,4-tetrahydroquinazoline oximes.[16–19]
A comparison of the 1H NMR and 13C NMR spectra of these
ligands with those of the Co(III) complexes confirms the co-
ordination of the aniline-type chain form of the ligands. In the
1H NMR spectra of the Co(III) complexes, there is no OH peak
belonging to the oxime group, providing evidence for deproto-
nation of the ligands. The chemical shift belonging to the NH
adjacent to the CH2 group in the HL1 and HL2 disappeared
In the FT-IR spectra of the Co(III) complexes, the ν(O H)
band due to water molecule was assigned at 3600–3250 cm−1
.
This very broad band prohibits the appearance of other bands in
the region. Regarding the FT-IR spectra of the Co(III) com-
plexes, the stretching vibration band was determined to be
caused by the imine group ( C N) and the band correspond-
ing to the ( C N ) vibration of the heterocyclic ring was
disappeared as results of the complexation and formation of
chain form within the complexes. These results show that
the ligands are converting to chain form in the Co(III) com-
plexes and they are coordinating to the metal ion in the chain
form.
Compared the FT-IR spectra of Co(III) complexes with the
FT-IR spectra of free ligands the displacement of the bands
to lower or upper frequencies were observed. This proofs the
coordination of the ligands to the Co(III) ion. For example,
when the FT-IR spectra of the complexes are compared with
those of the free ligands, the ν(C Noxime) band is shifted to a
lower frequency. This situation indicates that the oxime nitrogen
must be coordinated to the metal ion. The ν(N O) band in the
Co(III) complexes is situated at a frequency significantly higher
than that of the free ligands, owing to the coordination of the
N atom and the increase in bond order of the N O bond upon
deprotonation.
1
from the H NMR spectra of the Co(III) complexes. After the
complexation, in the integrated 1H NMR spectra of the Co(III)
complexes, the observed proton resonances at ca. δ 7.5 ppm
are due to the presence of the NH2 groups. The peaks were
assigned by the formation of the aniline-type chain form in the
Co(III) complexes (Scheme 2).
In the Co(III) complexes, the peaks due to the H C N
group and methylene group of the ligands showed an upfield
shift and a downfield shift upon complexation with Co(III), re-
spectively.[17–19] These findings confirm that the nitrogen atoms
of the oxime group and imine group are coordinated to the
Co(III) ion.
The chemical shift due to the quaternary carbon atom in the
ligands disappeared from the 13C NMR spectra of the Co(III)
complexes. However, after complexation a new resonance at δ
ca. 173 ppm was observed. The new resonance shows us that
the heterocyclic ring of the ligands was opened during the com-
plexation and the aniline-type chain form occurred in the Co
(III) complexes.[17–19] The chemical shifts belonging to the car-
bon atoms of oxime group and methylene group in the ligands
showed an upfield shift and a downfield shift on complexation
with Co(III). These results demonstrate the involvement of the
oxime nitrogen and the nitrogen adjacent to the CH2 group in
coordination.
1H and 13C NMR Spectra
In the 1H NMR spectra of the ligands, a singlet peak for the
OH proton of oxime group is observed at δ 10.94 ppm. The
NH proton adjacent to the CH2 group and other NH proton
in the heterocyclic ring resonate at δ 3.31–3.24 ppm (1H as
a multiplet) and δ 6.78 ppm (1H as a singlet) for HL1 and δ
3.29–3.25 ppm (1H as a multiplet) and at δ 6.80 ppm (1H as
a singlet) for HL2. The CH2 group in the heterocyclic ring
of the ligands resonates at δ 3.70 ppm and δ 3.46–3.40 ppm.
Thermal Analyses
Thermal behaviors of the ligands and Co(III) complexes have
The aldehyde proton adjacent to the oxime group resonates at been investigated using thermal analysis techniques. The ther-
7.44 ppm for the ligands. The integration of the 1H NMR spectra mal stability data are listed in Table 1. The ligands are stable up
suggests the presence of a range of proton resonances between to ca. 130◦C and then decompose in three separate temperature
7.72 and 6.46 ppm because of the resonance of 8 phenyl protons regions. Decompositions are completed at 618◦C for the ligands
of the ligands.
(Figures 1 and 2).

NEW TETRAHYDROQUINAZOLINES AND CO(III) COMPLEXES
631
TABLE 1
TG-DTA data of the ligands and their Co(III) complexes
Temperature
Total weight loss
Found, %
Compound
HL1
range, ◦C
DTAmax, ◦C
Calculated, %
Assignment
∗
∗
∗∗
∗∗
138–186
186–439
439–618
25–198
198–232
232–684
684–942
130–178
157 (−)
347 (DTGmax
570 (−)
15.9
61.4
100
)
100
2∗.6
–
ꢁ
82 (+)
2.4
[Co(L1 )2]Cl
1ꢁ
∗∗
[Co(L )2]Cl·H2O
217 (−)
19.5
88.5
89.4
11.2
∗
624 (−)
Co3O4/CoO
927 (+)
89.1
CoO
∗
∗∗
157 (−)
HL2
291(DTGmax)
∗
∗∗
178–425
425–618
51.9
100
365 (DTGmax
)
550 (−)
100
2∗.3
–
593 (−)
78 (+)
ꢁ
25–172
172–228
2.2
17.9
[Co(L2 )2]Cl
2ꢁ
∗∗
[Co(L )2]Cl· H2O
214 (−)
643 (−)
∗
228–720
720–948
90.4
91.1
Co3O4/CoO
CoO
690 (−)
922 (+)
90.3
(+): endothermic, (−): exothermic, ∗: not computed, ∗∗: unknown.
TG, DTG, and DTA curves for the Co(III) complexes are water molecule. On heating the complex (2) also releases one
given in Figures 3 and 4. It is rather difficult to comment on water molecule in the range of 25 to 172◦C. The loss of weight
the mass loss calculated in the thermal analysis of these com- found from TG curve is 2.2% and calculated as 2.3%. This value
plexes because of the lack of smooth plateaux. However, DTA confirms the release of one water molecule. The following two
curves indicate that the decomposition can occur in four steps exothermic steps are related to the release of HLn ligands and
between 25 and 950◦C. The first mass loss corresponds to the counter ion for the complexes. The mixture of Co3O4/CoO is
removal of the hydrated water from the complex (1) between caused by the removal of the organic ligands and counter ion.
25 and 198◦C. The loss of mass found from TG curve is equal The decomposition product Co3O4 is converted to CoO between
to 2.4% (calcd. 2.6%) which corresponds to the release of one 684 and 942◦C for (1) (DTAmax: 927◦C) and between 720 and
110.0
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
110.0
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
180.0
160.0
140.0
120.0
100.0
80.0
180.0
160.0
140.0
120.0
100.0
80.0
3.500
3.000
2.500
2.000
1.500
1.000
0.500
0.000
-0.500
-1.000
TG
TG
2.500
2.000
1.500
1.000
0.500
0.000
-0.500
60.0
60.0
40.0
40.0
DTG
DTA
DTG
DTA
20.0
20.0
0.0
0.0
-10.0
-20.0
-10.0
100.0
200.0
300.0
400.0
500.0
600.0
700.0
800.0
900.0
100.0
200.0
300.0
400.0
500.0
600.0
700.0
800.0
900.0
Temperature (C)
Temperature (C)
FIG. 1. TG, DTG, and DTA curves of HL1.
FIG. 2. TG, DTG, and DTA curves of HL2.

632
H. M. GENC¸ KAL ET AL.
quinazoline type phosphodiesterase 7 inhibitors in cellular cultures and
110.0
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
200.0
150.0
100.0
50.0
3.500
3.000
2.500
2.000
1.500
1.000
0.500
0.000
experimental stroke model. Eur. J. Med. Chem. 2012, 47, 175–185.
5. Hunoor, R.S.; Patil, B.R.; Badiger, D.S.; Vadavi, R.S.; Gudasi, K.B.; Mag-
annavar, C.V.; Muchandi, I.S. A study of anti-inflammatory and analgesic
activity of new 2,3-disubstituted 1,2-dihydroquinazolin-4(3H)-one deriva-
tive and its transition metal complexes. Chem. Pharm. Bull. 2010, 58(5),
712–716.
6. Esparza-Ruiz, A.; Pena-Hueso, A.; Mijangos, E.; Osorio-Monreal, G.;
Noth, H.; Flores-Parra, A.; Contreras, R.; Barba-Behrens, N. Cobalt(II),
nickel(II) and zinc(II) coordination compounds derived from aromatic
amines. Polyhedron 2011, 30(12), 2090–2098.
TG
DTA
DTG
7. Rai, B.K.; Singh, V.; Vidyarthi, S.N.; Sinha, P. Synthesis and study of
Co(II), Ni(II) and Cu(II) complexes with Schiff base ligands derived from
3-amino-2-phenyl-4(3H)-quinazoline one. Asian J. Chem. 2011, 23(10),
4638–4640.
0.0
-50.0
100.0
200.0
300.0
400.0
500.0
Temperature (C)
600.0
700.0
800.0
900.0
8. Cabeza, J.A.; Pruneda, V. Reactions of phthalazine, quinazoline, 4,7-
phenanthroline and 2,3ꢁ-bipyridine with ruthenium carbonyl. Dalton T.
2012, 41(24), 7249–7257.
ꢁ
FIG. 3. TG, DTG, and DTA curves of [Co(L1 )2]Cl·H2O.
9. Esparza-Ruiz, A.; Pena-Hueso, A.; Ramos-Garc´ıa, I.; Flores-Parra, A.;
Contreras, R. Heptacoordinated diphenyllead; hexa- and pentacoordi-
nated triphenyllead and tin compounds derived from 5H-benzimidazo[1,2-
c]quinazoline-6-thione. J. Organomet. Chem. 2008, 693(16), 2739–2747.
10. Vashi, R.T.; Shelat, C.D.; Patel, H. Synthesis, characterization and antifun-
gal activity studies on quinazoline-4-one derivatives containing 8-hydroxy
quinazoline ligand and its metal chelates. Asian J. Chem. 2010, 22(10),
7693–7698.
11. Rai, B.K.; Sharma, K.K. Synthesis, characterization and Antimicrobial
Study of Co(II), Ni(II) and Cu(II) Complexes of 2-Phenyl-3-carboxy
methyl quinazoline-(3H)-4-semicarbazone. Asian J. Chem. 2010, 22(7),
5625–5630.
12. Sawant, V.A.; Yamgar, B.A.; Sawant, S.K.; Chavan, S.S. Synthe-
sis, structural characterization, thermal and electrochemical studies of
mixed ligand Cu(II) complexes containing 2-phenyl-3-(benzylamino)-
1,2-dihydroquinazoline-4-(3H)-one and bidentate N-donor ligands. Spec-
trochim. Acta Part A 2009, 74(5), 1100–1106.
110.0
4.000
3.000
2.000
1.000
0.000
-1.000
TG
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
200.0
150.0
100.0
50.0
DTG
DTA
0.0
100.0
200.0
300.0
400.0
500.0
Temperature (C)
600.0
700.0
800.0
900.0
13. Gudasi, K.B.; Patil, S.A.; Vadavi, R.S.; Shenoy, R.V. Crystal structure of
2-[2-hydroxy-3-methoxyphenyl]-3-[2-hydroxy-3-methoxybenzylamino]-
1,2-dihydroquinazolin -4(3H)-one and the synthesis, spectral and thermal
investigation of its transition metal complexes. Transit. Metal Chem. 2006,
31, 586–592.
14. Garc´ıa-Deibe, A.M.; Sanmart´ın-Matalobos, J.; Gonza´lez-Bello, C.; Lence,
E.; Portela-Garc´ıa, C.; Mart´ınez-Rodr´ıguez, L.; Fondo, M. Metal-assisted
ring-closing/opening process of a chiral tetrahydroquinazoline. Inorg.
Chem. 2012, 51, 1278–1293.
15. Luo, H.Y.; Zhang, X.B.; Hea, C.L.; Shen, G.L.; Yu, R.Q. Synthesis of dipi-
colylamino substituted quinazoline as chemosensor for cobalt(II) recog-
nition based on excited-state intramolecular proton transfer. Spectrochim.
Acta Part A 2008, 70, 337–342.
16. C¸ olak, A.T.; Tas¸, M.; Irez, G.; Yes¸ilel, O.Z.; Bu¨yu¨kgu¨ngo¨r, O. Synthe-
ses, Spectral, Thermal and Structural Characterization of 2-Phenyl-2-(1-
hydroxyiminoethyl)-1,2,3,4-tetrahydroquinazoline and Its Novel Nickel(II)
Complex. Z. Anorg. Allg. Chem. 2007, 633, 504–508.
ꢁ
FIG. 4. TG, DTG, and DTA curves of [Co(L2 )2]Cl·H2O.
948◦C for (2) (DTAmax: 922◦C). These findings demonstrate
that the organic ligand acts as a reducing agent during thermal
decomposition. The final decomposition product of the com-
plexes is CoO [found: 10.6%, calcd.: 10.9% for (1) and found:
8.9%, calcd.: 9.7% for (2)].
REFERENCES
1. He, J.; Wang, X.; Zhao, X.; Liang, Y.; He, H.; Fu, L. Synthesis and antitu-
mor activity of novel quinazoline derivatives containing thiosemicarbazide
moiety. Eur. J. Med. Chem. 2012, 54, 925–930.
2. Mani Chandrika, P.; Yakaiah, T.; Raghu Ram Rao, A.; Narsaiah, B.;
Chakra Reddy, N.; Sridhar, V.; Venkateshwara Rao, J. Synthesis of novel
4,6-disubstituted quinazoline derivatives, their anti-inflammatory and anti-
cancer activity (cytotoxic) against U937 leukemia cell lines. Eur. J. Med.
Chem. 2008, 43, 846–852.
3. El-Azab, A.S.; ElTahir, K.E. H. Design, synthesis and anticonvulsant eval-
uation of novel 8-substituted-4(3H)-quinazolines. Med. Chem. Res. 2012,
21, 3785–3796.
17. Mutlu, H.; Irez, G. Synthesis and characterization of new tridentate imi-
nooxime ligands and their Co(III) complexes. Turk. J. Chem. 2008, 32,
731–741.
18. Mutlu, H.; Irez, G.; C¸ olak, A.T.; Yılmaz, F. Syntheses and characterizations
of a novel 1,2,3,4-tetrahydroquinazoline and a Co(III) complex. J. Coord.
Chem. 2012, 65, 2192–2200.
19. S¸irikc¸i, G.; Irez G.; Mutlu Genc¸kal, H. 2-(Naphthalen-2-yl)-1,2,3,4-
tetrahydroquinazoline-2-carbaldehyde oxime and Co(III) and Ni(II) com-
plexes of tridentate ligand containing oxime, imine and amine donor groups:
syntheses, characterisation and thermal properties, Acta Chim. Slov. 2012,
59(4), 904–911.
4. Redondo, M.; Zarruk, J.G.; Ceballos, P.; Pe´rez, D.I.; Pe´rez, C.; Perez-
Castillo, A.; Moro, M.A.; Brea, J.; Val, C.; Cadavid, M.I.; Loza,
M.I.; Campillo, N.E.; Mart´ınez, A.; Gil, C. Neuroprotective efficacy of

NEW TETRAHYDROQUINAZOLINES AND CO(III) COMPLEXES
633
20. Go¨blo¨ys, A.; La´za´r, L.; Fu¨lo¨p, F. Ring-chain tautomerism of 2-aryl-
substituted-hexahydropyrimidines and tetrahydroquinazolines. Tetrahe-
dron. 2002, 58, 1011–1016.
22. Bergman, J.; Engqvist, R.; Sta˚lhandske, C.; Wallberg, H. Studies of the reac-
tions between indole-2,3-diones (isatins) and 2-aminobenzylamine. Tetra-
hedron. 2003, 59, 1033–1048.
21. Sinkkonen, J.; Zelenin, K.N.; Potapov, A.K. A.; Lagoda, I.V.;
Alekseyev, V.V.; Pihlaja, K. Ring-chain tautomerism in 2-substituted
1,2,3,4-tetrahydroquinazolines A 1H, 13C and 15N NMR study. Tetrahe-
dron 2003, 59, 1939–1950.
23. Chhakkar, A.K.; Kakkar, L.R. Spectrophotometric determination of palla-
dium using 2−(2−hydroxyimino−1−oxoethyl)thiophene. B. Chem. Soc.
Jpn. 1991, 64, 3075–3078.