Facile Synthesis and Photophysical Characterization of New Quinoline Dyes

Article abstract of DOI:10.1007/s10895-016-1954-5

This paper describes the synthesis of new quinoline derivatives, molecules that has been long interest in the organic and medicinal chemistry. Through the Multicomponent Reaction (MCR), an important tool in modern synthetic methodology, that generate products with good structural complexity, in addition to economy of atoms and selectivity, we provide easy access to the preparation of quinoline derivatives. The reactions were promoted by niobium pentachloride, as a Lewis acid. Subsequently, the synthesis of new aminoquinoline derivatives with good yields was performed using Pd/C and hydrazine. The photophysical investigations of quinoline derivatives show the substituent effect on the optical properties characterization was done by absorption and photoluminescence measurements with quantum yields of up to 83?%, the presence of the amino group at position 6 at the quinoline backbone was crucial for obtaining these increased quantum yields. Results show that these molecules may have potential use for a variety of applications and mainly attracts attention because of its wide potential of applicability in optoelectronic devices.

Full text of DOI:10.1007/s10895-016-1954-5

J Fluoresc
DOI 10.1007/s10895-016-1954-5
ORIGINAL ARTICLE
Facile Synthesis and Photophysical Characterization
of New Quinoline Dyes
Giovanny Carvalho dos Santos1 & Aloisio de Andrade Bartolomeu1
Valdecir Farias Ximenes1 & Luiz Carlos da Silva-Filho1
&
Received: 18 August 2016 /Accepted: 19 October 2016
#
Springer Science+Business Media New York 2016
Abstract This paper describes the synthesis of new quinoline
derivatives, molecules that has been long interest in the organ-
ic and medicinal chemistry. Through the Multicomponent
Reaction (MCR), an important tool in modern synthetic meth-
odology, that generate products with good structural complex-
ity, in addition to economy of atoms and selectivity, we
provide easy access to the preparation of quinoline de-
rivatives. The reactions were promoted by niobium
pentachloride, as a Lewis acid. Subsequently, the synthesis
of new aminoquinoline derivatives with good yields was per-
formed using Pd/C and hydrazine. The photophysical investi-
gations of quinoline derivatives show the substituent effect on
the optical properties characterization was done by absorption
and photoluminescence measurements with quantum yields of
up to 83 %, the presence of the amino group at position 6 at the
quinoline backbone was crucial for obtaining these increased
quantum yields. Results show that these molecules may have
potential use for a variety of applications and mainly attracts
attention because of its wide potential of applicability in op-
toelectronic devices.
Introduction
The development of new synthetic strategies for the efficient
production of organic compounds is very important, especial-
ly when it comes to compounds such as quinoline derivatives
which have a variety of applications in many areas and are
present in various natural products and drugs [1, 2]. Thus, this
compound has been the subject of numerous research groups.
Besides the great biological applicability of the quinoline de-
rivatives, such as anti-inflammatory [3, 4], anti-cancer [5–9],
anti-hypertensive [10–13], antibacterial [14–17] and antifun-
gal [18, 19] agents, there are also several studies aiming to
take advantage of their excellent mechanical properties.
For example, their application in polymer chemistry, or-
ganic electronics and optoelectronics [20–24]. Also, the
aminoquinolines that act as fluorophores show potential
performance as organic semiconductors [25]. In addi-
tion, some derivatives of substituted quinolines have
been used as ligands for the preparation of phosphores-
cent complexes used in organic light-emitting diodes
(OLEDs) [26–28]. The diphenylaminoquinolines have
shown to be a promising luminescent organic material
with emission in blue range [29, 30]. Other derivatives are
presented as potential candidates for applications in fiber op-
tics, photonics and light emitting diodes [31–34]. The litera-
ture shows that quinoline backbone is found in several natural
products [35].
.
Keywords Niobium pentachloride Multicomponent
.
.
.
reactions Quinoline derivatives Photoluminescence
Fluorescence quantum yields
Electronic supplementary material The online version of this article
(doi:10.1007/s10895-016-1954-5) contains supplementary material,
which is available to authorized users.
For dye applications in OLEDs, it is known that a higher
value of short-circuit current density (Jsc) is assigned to mol-
ecules bearing a broad and intense absorption spectrum [36].
This is the case of molecules containing the quinoline back-
bone as π spacer, where the increase in the energy conversion
efficiency reaches 6.07 % [36]. Zhang et al. showed a great
improvement in OLEDs luminescence efficiency and bright-
ness when quinoline derivatives were used [37].
* Luiz Carlos da Silva-Filho
lcsilva@fc.unesp.br
1
Laboratory of Organic Synthesis and Processes (LOSP), Department
of Chemistry, Faculty of Sciences, São Paulo State University
(UNESP), 17033-360, Bauru, São Paulo, Brazil

J Fluoresc
Some classical methods of synthesis are described in the
literature to give support for new synthesis [38–68]. Because
of this potential applicability of quinoline derivatives,
many research groups have geared their efforts towards
the development of new efficient and low cost synthetic
methods. For the synthesis of quinoline derivatives, sev-
eral types of catalysts may be used. It has also been
shown that acid catalysts are superior to some of the
basic types of reactions [44].
Therefore, in this work we describe the facile synthesis and
the optical characterization of new nitroquinoline and
aminoquinoline derivatives, compounds with potential appli-
cation as dyes in organic electronic devices.
and n is the refractive index of the solvents used.
Subscript std. denotes the standard. The compounds
were solubilized in ethanol and the concentration maintained
at about 5 × 10−6 mol.L−1 to follow the protocol for analysis
[69].
Synthesis
General Procedure for the Synthesis of Nitroquinoline
Derivatives
To a solution of NbCl5 (50 mol%) in 7.0 mL of anhydrous
acetonitrile, maintained at room temperature, under air atmo-
sphere, we added a solution of p-nitroaniline (1.0 mmol),
phenylacetylene (1.0 mmol) and benzaldehyde derivatives
(2a–x) (1.0 mmol) in 3.0 mL of anhydrous acetonitrile. The
reaction mixture was quenched with water (3.0 mL) after 96 h.
The mixture was extracted with ethyl acetate (10.0 mL). The
organic layer was separated and washed with saturated
sodium bicarbonate solution (3 × 10.0 mL), saturated
brine (2 × 10.0 mL), and then dried over anhydrous
magnesium sulfate. The solvent was removed under vacu-
um. The resulting mixture obtained was recrystallized in
CH3OH. In some cases more than one recrystallization
process was needed [70].
Experimental
Materials and Instrumentation
All reactions were performed under air atmosphere, unless
otherwise specified. Acetonitrile was distilled from calcium
hydride. All commercially available reagents were used with-
out further purification. The NbCl5 used was supplied by
Companhia Brasileira de Metalurgia e Mineração (CBMM).
Thin-layer chromatography was performed on 0.2 mm Merck
60F254 silica gel aluminum sheets, which were visualized with
a vanillin/methanol/water/sulfuric acid mixture, molybdate or
UV-365 nm irradiation. Bruker DRX 400 spectrometer was
employed for the NMR spectra (CDCl3 solutions) using
General Procedure for the Synthesis of Aminoquinoline
Derivatives
1
An ethanol suspension (20.0 mL) of quinoline derivative
(4a–x) (1.0 mmol) was heated to 50.0 °C in the pres-
ence of 10%Pd/C and 2.00 mL of hydrazine
monohydrate was added over 30 min to this suspension.
The reaction mixture became clear as the reaction
proceeded. It was kept at reflux for another 12 h.
Upon completion of reaction, the mixture was filtered
over Celite twice to remove the Pd/C catalyst. Ethanol
was removed under reduced pressure. The crude product
was recrystallized from isopropanol. Note: the crystals
grew slowly [25].
tetramethylsilane as internal reference for H and CDCl3 as
an internal reference for 13C. A Bruker FTIR model VERTEX
70 was used to record IR spectra (neat). HRMS analyses were
recorded in a micrOTOF (Bruker), with ESI-TOF detector
working on positive mode. Absorption spectra in the UV-Vis
region were obtained in an apparatus from Molecular Devices
(Model SpectraMax M2) using a quartz cuvette of 1 cm light
path at room temperature. Fluorescence emission curves were
obtained using a spectrophotometer BioTek microplate
(Model Synergy H1).
Quantum yields were analyzed by adjusting the solution
absorption using the UV-Vis to ca. 0.05 at 325–393 nm wave-
length, the output was measured using the luminescence spec-
trophotometer at the same wavelength and comparing it to the
known 9,10-diphenylanthracene standard using Eq. 1:
Equation 1: Quantum yield calculation using 9,10-
diphenylanthracene
Results and Discussion
Synthesis and Characterization
Recently, our research group described the synthesis of quin-
oline derivatives through multicomponent reaction (MCR)
between arylaldehydes, anilines and alkynes catalyzed by
Niobium Pentachloride [71]. In this work, we describe the
synthesis of nitroquinoline derivatives by MCRs, using the
promoter NbCl5, followed by the reduction of nitro groups
for obtaining the aminoquinoline derivatives.
Astd
AFstd
F
n2
n2std
Φf ¼ Φstdx
x
Φ is the fluorescence quantum yield, A is the absorption of the
excitation wavelength, F is the area under the emission curve,

J Fluoresc
Scheme 1 Synthesis of aminoquinolines 5a–x in two steps
The MCRs were conducted between p-nitroaniline (1)
(1.0 eq.), benzaldehyde derivatives (2a–x) (1.0 eq.) and
phenylacetylene (3) (1.0 eq.) under air atmosphere, room
temperature, constant stirring and using anhydrous ace-
tonitrile (CH3CN) as solvent. NbCl5 was used in the
proportion of 50 % for each mol of benzaldehyde derivative
used.
Reduction of nitro group in the nitroquinoline derivatives
was conducted with hydrazine monohydrate in the pres-
ence of 10 % Pd/C (Scheme 1). The results are summarized
in Table 1.
The MRCs in the presence of NbCl5 showed good yields
for the production of nitroquinoline derivatives, regardless of
the benzaldehyde derivatives used. The results were better
using derivatives containing electron withdrawing substitu-
ents, which improve the coordination of the benzaldehyde
with the Lewis acid (NbCl5) and facilitate the subsequent ad-
dition of the amine group of p-nitroaniline to the carbonyl
group of the benzaldehyde [72]. The reactions with m-
nitrobenzaldehyde and p-nitrobenzaldehyde (4v and 4x)
showed lower yields due to the poor solubility of these com-
pounds. To support the good results of the first step, in Table 2
Table 1 Benzaldehyde
derivatives utilized and reaction
yields
Aldehyde
R1
R2
R3
R4
R5
Nitroquinoline
yield(%)a
Aminoquinoline
yield(%)a
2a
2b
2c
2d
2e
2f
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH3
H
H
H
93 (4a)
87(4b)
92(4c)
81(4d)
75(4e)
98(4f)
92 (5a)
91 (5a)
94 (5a)
93 (5a)
84 (5a)
92 (5a)
90 (5a)
84 (5a)
80 (5a)
87 (5a)
74 (5 k)
90 (5l)
85 (5 m)
65 (5n)
70 (5o)
72 (5p)
92 (5q)
91 (5r)
93 (5s)
89 (5t)
91 (5u)
84 (5v)
82 (5x)
F
H
H
Cl
Br
H
H
H
H
H
F
H
H
Cl
Br
H
H
2g
2h
2i
H
H
79(4 g)
98(4 h)
86(4i)
H
F
H
H
Cl
2j
H
H
Br
98(4j)
2k
2l
OCH3
H
H
H
93 (4 k)
79 (4 l)
71 (4m)
83(4n)
78(4o)
82 ) (4p)
98 (4q)
70 ) (4r)
78(4s)
OCH3
H
H
2m
2n
2o
2p
2q
2r
2s
H
OCH3
H
CH3
H
H
CH3
H
H
H
CH3
C6H5
N(CH3)2
C(CH3)3
CH3
SCH3
NO2
H
H
H
H
H
H
H
2t
CH3
H
H
79 (4t)
75 (4u)
56(4v)
54(4x)
2u
2v
2x
H
H
H
H
NO2
a Yields of isolated products after recrystallization

J Fluoresc
Table 3 Maximum absorption wavelength (λmax) for quinoline
derivatives
are shown the yields when compared to others catalysts [24,
73–80], we note that the NbCl5 promotes MCRs with good
yields in milder conditions. The efficiency of this catalyst is
highlighted by the conduction of reactions at room tempera-
ture and pressure, and air atmosphere. These factors could
reduce the cost of large-scale production.
Compound
λmax(nm) ethanol
Compound
λmax(nm) ethanol
4a
4b
4c
4d
4e
4f
335
326
375
332
331
332
332
337
341
341
343
341
357
379
341
356
360
393
344
358
369
332
325
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
5k
5l
375
375
375
375
375
375
375
375
375
375
370
373
373
370
373
373
373
388
373
370
376
385
373
The second reaction step, the reduction of the nitro group in
all nitroquinoline derivatives, was successfully obtained and
presented good yields. An exception was the halogenated
nitroquinoline derivatives, in which the reductive reactional
condition also resulted in the dehalogenation of the products,
obtaining only the compound 5a as product. An explanation
for this fact is the small amount of reagents used in our exper-
iments, a condition different from those described in the liter-
ature. Indeed, Pd-catalyzed hydrogenolysis of carbon-halogen
bonds with hydrazine as a hydrogen donor is a long known
method, but it is usually performed with large amounts of
catalyst and/or reducing agent [81–85]. In short, this study
has shown that the conversion of polysubstituted quinolines
with fluorides, bromides and chlorides into corresponding
quinoline dehalogenated can be efficiently performed with
ethanol in the presence of hydrazine as hydrogen donor and
catalytic amounts of Pd/C. The chemical structures of
the resulting nitroquinoline and aminoquinoline deriva-
tives were confirmed by 1H NMR, 13C NMR, IR and
HRMS spectra.
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
4s
5m
5n
5o
5p
5q
5r
5s
4t
5t
4u
4v
4x
5u
5v
5x
Photophysical Properties
UV-Vis Absorption Properties
As it is well known, substituents have a key effect on the
properties of fluorophores. In this study, we add different
types of substituents at various positions to examine the ef-
fects on absorption, emission and fluorescence quantum yield.
The photophysical characteristics were investigated in
CH3CH2OH solutions.
The data of UV-Vis absorption are summarized in Table 3 in
10−3 mol. L−1EtOH solution.
The absorption spectra of the nitroquinoline derivatives in
ethanol are characterized by strong absorption peaks centered
Table 2 Comparison of the data
Catalyst
Solvent
Temperature (C°)
Time (min)
Yield (%)
reported in literature and the
products obtained in the synthesis
of 6-nitro-2,4-diphenylquinoline
(4a)
1
2
3
4
5
6
7
8
9
10
NbCl5
CH3CN
----
r.t.
5760
8
93
63
90
69
77
93
72
90
87
61
YCl3
180 (MW) c
90 (MW)
100
K5CoW12O40.3H2O
Fe(OTf)3
In/HCl
----
10
----
180
1080
240
10
H2O
Reflux
Reflux
100 (MW)
90
H2SO4
K-10 a
CH3COOH
----
b
Zn(OTf)2
In(OTf)3
FeCl3
[hmim]PF6
----
120
300
45
110 (MW)
Reflux
CH3CN
a Montmorillonite [(Na,Ca)0,3(Al,Mg)2Si4O10(OH)2.nH2O]
b 1-hexyl-3-methylimidazolium hexafluorophosphate
c MW- Microwave irradiation

J Fluoresc
Fig. 1 UV-Vis absorption of
nitroquinoline derivatives (4a–x)
in ethanol
at 250–280 nm and 325–393 nm probably due to π-π* and
n-π* transitions, which are characteristics of conjugated quin-
oline backbone and phenyl side chains with or without sub-
stituents. The absorption spectra of ethanolic solutions
(10−3 mol.L−1) of nitroquinoline derivatives are depicted in
Fig. 1.
Analyzing the effect of the substituent groups using 4a (6-
nitro-2,4-diphenylquinoline) as the reference compound, it
can be observed a general tendency by which the compounds
containing electron withdrawing substituents showed lower
values of λmax when compared to electron donors. We also
observed that electron withdrawing substituents have greater
absorption when in para position. Electron withdrawing
groups such as nitro (NO2), in meta or para position showed
hypsochromic shift. The same was observed in the halogen
substituents (F, Cl and Br) in ortho and meta positions, except
chlorine in ortho position. A bathochromic shift was observed
for these halogens in para. On the other hand, electron donor
Fig. 2 UV-Vis absorption of
aminoquinoline derivatives
(5a–x) in ethanol

J Fluoresc
Table 4 Photophysical data obtained from UV-Vis absorption and fluo-
rescence emission of quinoline derivatives
substituents, such as methoxy (341–375 nm) and methyl
(341–379 nm) in any position, tert-butyl group (344 nm)
and thioether group (369 nm), also exhibited a bathochromic
shift. The compound that showed higher λmax was 4r
(393 nm) having dimethylamine as substituent, an electron
donating group. This phenomenon may be explained taking
into account the presence of a pair of non-bonding electrons
that are capable of interacting with π electrons of the aromatic
ring. Phenyl substituent had a bathochromic shift (360 nm)
because it has effectively extended the conjugation of the
molecule.
The change of electron withdrawing groups (NO2) by the
electron donating group (NH2) had profound influence in the
spectral properties. As it can be observed, a difference of
40 nm was seen between molecule 4a and 5a, a bathochromic
shift due to the change of the electron withdrawing groups
(NO2) by the electron donating group (NH2) at position 6 at
the quinoline backbone. In general, due to the strong influence
of amino group at position 6, no significant alteration was
observed by changing the substituents on the phenyl ring in
position 2 (370 nm to 376 nm) (Fig. 2). Molecules 5n and 5r
were exceptions when compared to 4n and 4r, exhibiting a
slight hypsochromic shift. There was a large bathochromic
shift in molecules with the amino groups 5v (385 nm) and
5x (373 nm). Again, para position showed higher values com-
pared to other positions.
Compound λem Δλst Φfx (%) Compound λem Δλst Φfx (%)
4a
4b
4c
4d
4e
4f
410 75
410 84
430 55
415 83
415 84
415 83
430 98
415 78
405 64
395 54
415 72
425 84
430 73
430 51
435 94
435 79
445 85
450 57
430 86
430 72
425 56
415 83
410 85
0.25
1.50
0.58
2.05
0.76
1.10
0.91
0.37
0.37
0.23
0.43
0.18
0.24
3.15
0.80
0.50
0.35
0.45
0.26
0.32
0.57
0.23
0.25
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
5k
5l
470 95
470 95
470 95
470 95
470 95
470 95
470 95
470 95
470 95
470 95
466 93
469 96
469 96
466 93
469 96
469 96
466 96
475 87
469 96
466 96
472 99
472 87
469 90
65.33
65.33
65.33
65.33
65.33
65.33
65.33
65.33
65.33
65.33
69.92
69.57
70.18
53.64
80.32
59.53
72.92
51.70
73.03
49.16
83.48
24.15
14.66
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
4s
5m
5n
5o
5p
5q
5r
5s
4t
5t
4u
4v
4x
5u
5v
5x
Emission Fluorescence Properties
Figure 3 shows the fluorescence emission of quinoline
derivatives.
Similar to the absorption effects, the fluorescence behavior
was also affected by the substituents and their positions.
Molecules 4a–x mostly show a similar behavior in the shift.
When the difference in fluorescence intensity was analyzed,
molecules 4n and 4g presented greater intensity. Fluorescence
emission spectra of derivatives 5a–x exhibited high intensity
and showed similar values even by altering the substituents.
a
b
Fig. 3 a Fluorescence emission of nitroquinoline derivatives (4a–x) in ethanol. b Fluorescence emission of aminoquinoline derivatives (5a–x) in
ethanol

J Fluoresc
Fig. 4 a Ethanolic Solutions of
4a, 5a and 5u. b Ethanolic
Solutions of 4a, 5a and 5u
irradiated by 365 nm UV
radiation
These high values are evidenced when compared to several
standards of fluorescence as 9,10-diphenylanthracene which
was the standard used for measures (Φfx = 90 % in ethanol)
[70]. These results confirmed the strong influence of the ami-
no group in the derivatives. The photophysical data of all
synthetized compounds are showed in Table 4.
that the diamine quinoline derivatives 5v and 5x could be used
as asymmetric monomers for the preparation of high perfor-
mance polymers [25]. Due to the unquestionable importance
of quinoline derivatives in several areas as the development of
pharmaceuticals, dyes, chemical polymers and in electronic
and organic optoelectronics devices, the MCRs methodology
developed here is of great interest for those who study these
molecules.
The fluorescence quantum yield (Φf) is one of the most
fundamental and important properties for materials with po-
tential application in fluorescence imaging, optical devices,
analysis and biosensing [86]. Here, we observed that the mol-
ecules 4a–x with nitro group in position 6 do not present
significant values of Φf. In contrast, the presence of the amino
group in this position was crucial for obtaining increased Φf,
as can be seen for aminoquinolines (5a–x) [25]. These high
values of fluorescence quantum yield of fluorescence con-
firmed the importance of the amino group and demonstrated
that fluorescence is not detected in aromatic compounds con-
taining the nitro group, as seen in molecules 4a–x. This is
likely due to the existence of transitions n → π*, causing an
efficient intersystem crossing process, and the great speed of
the internal conversion processes S0 → S1 [87].
Acknowledgments The authors would like to thank Fundação de
Amparo à Pesquisa do Estado de São Paulo (FAPESP) (Procs.
2013/08,697–0, 2012/24,199–8, 2015/00,615–0 and 2016/01,599–1),
Conselho Nacional de Desenvolvimento Científico e Tecnológico
(CNPq) (Proc. 302,753/2015–0) and Pró-Reitoria de Pesquisa
(PROPe-UNESP) for their financial support. We would also like
to thank CBMM – Companhia Brasileira de Mineralogia e
Mineração for the NbCl5 samples. We express our special thanks to N.
P. Lopes, J. N. Mendonça and J. C. Tomaz at the University of São Paulo
in Ribeirão Preto for the HRMS analyses.
References
Values of Stokes shifts are between 51 and 98 nm for com-
pounds containing the nitro group (4a–x) and 87 to 100 nm for
the aminoquinolines (5a–x). This shows energy loss in the
excited state due to rearrangements or structural changes of
molecules. In Fig. 4, compounds irradiated with ultraviolet
light showed blue fluorescence for the aminoquinolines.
1. Michael JP (1997) Quinoline, quinazoline and acridone alkaloids.
Nat Prod Rep 14(6):605–618
2. Campbell SF, Hardstone JD, Palmer MJ (1988) 2, 4-Diamino-6, 7-
dimethoxyquinoline derivatives as. Alpha. 1-adrenoceptor antago-
nists and antihypertensive agents. J Med Chem 31(5):1031–1035
3. Pellerano, C., Savini, L., Massarelli, P., Bruni, G., & Fiaschi, A. I.
(1990). New quinoline derivatives: synthesis and evaluation for
antiinflammatory and analgesic properties–Note I. Farmaco
(Società chimica italiana: 1989), 45(3), 269.
4. Roma G, Di Braccio M, Grossi G, Mattioli F, Ghia M (2000) 1, 8-
Naphthyridines IV. 9-substituted N, N-dialkyl-5-(alkylamino or
cycloalkylamino)[1, 2, 4] triazolo [4, 3-a][1, 8] naphthyridine-6-
carboxamides, new compounds with anti-aggressive and potent
anti-inflammatory activities. Eur J Med Chem 35(11):1021–1035
5. Kociubinska A, Gubernator J, Godlewska J, Stasiuk M, Kozubek
A, Peczynska-Czoch W et al (2002) A derivative of 5-H-indolo [2,
3-b] quinoline-a novel liposomally-formulated anticancer agent.
Cell Mol Biol Lett 7(2)
Conclusion
In conclusion, NbCl5 proved to be an excellent catalyst for
MCRs. The reactions were conducted in mild conditions, with
low production cost and with good yields. The optical prop-
erties were dependent on the substituents, showing lower
values of maximum absorption for the electron withdrawing
substituents when compared to electron donors. The substitu-
ents positions were also important. Compounds 4a–x exhibit-
ed low values of Φf and aminoquinolines (5a–x) showed high
values. In this context, compounds like 5r are potential can-
didates for organic electronic devices. The results also show
6. Joseph B, Darro F, Béhard A, Lesur B, Collignon F, Decaestecker C
et al (2002) 3-Aryl-2-quinolone derivatives: synthesis and charac-
terization of in vitro and in vivo antitumor effects with emphasis on
a new therapeutical target connected with cell migration. J Med
Chem 45(12):2543–2555

J Fluoresc
7. Heiniger B, Gakhar G, Prasain K, Hua DH, Nguyen TA (2010)
Second-generation substituted quinolines as anticancer drugs for
breast cancer. Anticancer Res 30(10):3927–3932
8. Stauffer F, Maira SM, Furet P, García-Echeverría C (2008) Imidazo
[4, 5-c] quinolines as inhibitors of the PI3K/PKB-pathway. Bioorg
Med Chem Lett 18(3):1027–1030
9. Maguire MP, Sheets KR, McVety K, Spada AP, Zilberstein
A (1994) A new series of PDGF receptor tyrosine kinase
inhibitors: 3-substituted quinoline derivatives. J Med Chem
37(14):2129–2137
25. Nedeltchev AK, Han H, Bhowmik PK (2010) Tetrahedron 66:9319
26. Chen X, Qiu D, Ma L, Cheng Y, Geng Y, Xie Z, Wang L (2006)
Synthesis, crystal structure, spectroscopy and electroluminescence
of zinc (II) complexes containing bidentate 2-(2-pyridyl) quinoline
derivative ligands. Transit Met Chem 31(5):639–644
27. Kim JI, Shin IS, Kim H, Lee JK (2005) Efficient electrogenerated
chemiluminescence from cyclometalated iridium (III) complexes. J
Am Chem Soc 127(6):1614–1615
28. Thompson ME, Ma B, Djurovich P (2005)U.S. patent.
20050164031A1
10. Muruganantham N, Sivakumar R, Anbalagan N, Gunasekaran V,
Leonard JT (2004) Synthesis, anticonvulsant and antihypertensive
activities of 8-substituted quinoline derivatives. Biol Pharm Bull
27(10):1683–1687
11. Conklin JD, Hollifield RD (1970) Studies on the absorption, distri-
bution, and elimination of amiquinsin hydrochloride, a hypotensive
drug. Eur J Pharmacol 10(3):360–368
12. Jandhyala BS, Grega GJ, Buckley JP (1967) Hypotensive activity
of several quinoline derivatives. Arch Int Pharmacodyn Ther
167(1):217
13. Ferrarini PL, Mori C, Badawneh M, Calderone V, Greco R, Manera
C et al (2000) Synthesis and β-blocking activity of (R, S)-(E)-
oximeethers of 2, 3-dihydro-1, 8-naphthyridine and 2, 3-
dihydrothiopyrano [2, 3-b] pyridine: potential antihypertensive
agents–Part IX. Eur J Med Chem 35(9):815–826
14. Parekh N, Maheria K, Patel P, Rathod M (2011) Study on antibac-
terial activity for multidrug resistance stain by using phenyl
pyrazolones substituted 3-amino 1H-pyrazolon (3, 4-b) quinoline
derivative in vitro condition. Int. J. Pharm Tech Res 3:540–548
15. Eswaran S, Adhikari AV, Kumar RA (2010) New 1, 3-oxazolo [4,
5-c] quinoline derivatives: synthesis and evaluation of antibacterial
and antituberculosis properties. Eur J Med Chem 45(3):957–966
16. Eswaran S, Adhikari AV, Chowdhury IH, Pal NK, Thomas KD
(2010) New quinoline derivatives: synthesis and investigation of
antibacterial and antituberculosis properties. Eur J Med Chem
45(8):3374–3383
17. Chen YL, Fang KC, Sheu JY, Hsu SL, Tzeng CC (2001) Synthesis
and antibacterial evaluation of certain quinolone derivatives. J Med
Chem 44(14):2374–2377
18. Musiol R, Jampilek J, Buchta V, Silva L, Niedbala H, Podeszwa B
et al (2006) Antifungal properties of new series of quinoline deriv-
atives. Bioorg Med Chem 14(10):3592–3598
19. Ryu CK, Lee JY, Jeong SH, Nho JH (2009) Synthesis and antifun-
gal activity of 1H-pyrrolo [3, 2-g] quinoline-4, 9-diones and 4, 9-
dioxo-4, 9-dihydro-1H-benzo [f] indoles. Bioorg Med Chem Lett
19(1):146–148
20. Dumouchel S, Mongin F, Trécourt F, Quéguiner G (2003)
Tributylmagnesium ate complex-mediated bromine–magnesium
exchange of bromoquinolines: a convenient access to functional-
ized quinolines. Tetrahedron Lett 44(10):2033–2035
21. Arisawa M, Theeraladanon C, Nishida A, Nakagawa M (2001)
Synthesis of substituted 1, 2-dihydroquinolines and quinolines
using ene–ene metathesis and ene–enol ether metathesis.
Tetrahedron Lett 42(45):8029–8033
22. Cho CS, Kim JS, Oh BH, Kim TJ, Shim SC, Yoon NS (2000)
Ruthenium-catalyzed synthesis of quinolines from anilines and
allylammonium chlorides in an aqueous medium via amine ex-
change reaction. Tetrahedron 56(39):7747–7750
23. Nedeltchev AK, Han H, Bhowmik PK (2010) Solution, thermal,
and optical properties of poly (pyridinium salt) s derived from an
ambipolar diamine consisting of diphenylquinoline and triphenyl
amine moieties. J Polym Sci A Polym Chem 48(20):4611–4620
24. Nedeltchev AK, Han H, Bhowmik PK (2010) Photoactive amor-
phous molecular materials based on quinoline amines and their
synthesis by Friedländer condensation reaction. Tetrahedron
66(48):9319–9326
29. Raut SB, Dhoble SJ, Park K (2013) Amino diphenyl quinoline: a
promising blue emitting organic luminescent material. Indian J
Phys 87(1):19–23
30. Dahule HK, Thejokalyani N, Dhoble SJ (2015) Novel Br-DPQ blue
light-emitting phosphors for OLED. Luminescence 30(4):405–410
31. He Z, Milburn GHW, Baldwin KJ, Smith DA, Danel A, Tomasik P
(2000) The efficient blue photoluminescence of pyrazolo-[3, 4-b]-
quinoline derivatives and the energy transfer in polymer matrices. J
Lumin 86(1):1–14
32. Koścień E, Sanetra J, Gondek E, Jarosz B, Kityk IV, Ebothe J,
Kityk AV (2004) Optical poling of several halogen derivatives of
pyrazoloquinoline. Opt Commun 242(4):401–409
33. Gondek E, Koścień E, Sanetra J, Danel A, Wisła A, Kityk AV
(2004) Optical absorption of 1H-pyrazolo [3, 4-b] quinoline and
its derivatives. Spectrochim Acta A Mol Biomol Spectrosc
60(13):3101–3106
34. Koścień E, Sanetra J, Gondek E, Danel A, Wisła A, Kityk AV
(2003) Optical absorption measurements and quantum-chemical
simulations on 1H-pyrazolo [3, 4-b] quinoline derivatives. Opt
Commun 227(1):115–123
35. Reddy BS, Venkateswarlu A, Reddy GN, Reddy YR (2013)
Chitosan-SO 3 H: an efficient, biodegradable, and recyclable solid
acid for the synthesis of quinoline derivatives via Friedländer an-
nulation. Tetrahedron Lett 54(43):5767–5770
36. Choi HJ, Choi HB, Paek SH, Song KH, Kang MS, Ko JJ (2010)
Novel organic sensitizers with a quinoline unit for efficient dye-
sensitized solar cells. Bull Kor Chem Soc 31(1):125–132
37. Zhang X, Kale DM, Jenekhe SA (2002) Electroluminescence of
multicomponent conjugated polymers. 2. Photophysics and en-
hancement of electroluminescence from blends of polyquinolines.
Macromolecules 35(2):382–393
38. Long R, Schofield K (1953) 630. Some alkylquinoline-5: 8-qui-
nones. J Chem Soc (Resumed):3161–3167
39. Roberts, E., & Turner, E. E. (1927). CCXXXIX.—The factors con-
trolling the formation of some derivatives of quinoline, and a new
aspect of the problem of substitution in the quinoline series. J Chem
Soc (Resumed), 1832–1857.
40. Gandeepan P, Rajamalli P, Cheng CH (2014) Synthesis of substitut-
ed quinolines by iron (III)-catalyzed three-component coupling re-
action of aldehydes, amines, and Styrenes. Asian J Org Chem 3(3):
303–308
41. Heindel ND, Brodof TA, Kogelschatz JE (1966) Cyclization of
amine-acetylene diester adducts: a modification of the conrad-
limpach method. J Heterocycl Chem 3(2):222–223
42. Hermecz I, Kereszturi G, Vasvaridebreczy L (1992)
Aminomethylenemalonates and their use in heterocyclic
synthesis-introduction. Adv Heterocycl Chem 54:1
43. Friedlaender P (1882) Ueber o-Amidobenzaldehyd. Ber Dtsch
Chem Ges 15(2):2572–2575
44. Fehnel EA (1966) Friedländer syntheses with o-Aminoaryl ketones.
I. Acid-catalyzed condensations of o-Aminobenzophenone with
ketones1. J Org Chem 31(9):2899–2902
45. Marco-Contelles J, Perez-Mayoral E, Samadi A, Carreiras MDC,
Soriano E (2009) Recent advances in the Friedlander reaction.
Chem Rev 109(6):2652–2671

J Fluoresc
46. Dormer PG, Eng KK, Farr RN, Humphrey GR, McWilliams JC,
Reider PJ et al (2003) Highly regioselective Friedländer annulations
with unmodified ketones employing novel amine catalysts: synthe-
ses of 2-substituted quinolines, 1, 8-naphthyridines, and related
heterocycles. J Org Chem 68(2):467–477
47. McNaughton BR, Miller BL (2003) A mild and efficient one-step
synthesis of quinolines. Org Lett 5(23):4257–4259
48. Bose DS, Kumar RK (2006) An efficient, high yielding protocol for
the synthesis of functionalized quinolines via the tandem addition/
annulation reaction of o-aminoaryl ketones with α-methylene ke-
tones. Tetrahedron Lett 47(5):813–816
the synthesis of N-polyheterocycles and related alkaloids.
Tetrahedron 65(14):2721–2750
66. Kouznetsov VV, Bohorquez ARR, Stashenko EE (2007) Three-
component imino Diels–Alder reaction with essential oil and seeds
of anise: generation of new tetrahydroquinolines. Tetrahedron Lett
48(50):8855–8860
67. Tarantin AV, Glushkov VA, Mayorova OA, Shcherbinina IA,
Tolstikov AG (2008) The Povarov reaction of ethyl (18-
carbomethoxyabieta-8, 11, 13-triene-12-imino) glyoxylate
with electron-donating dienophiles. Mendeleev Commun
18(4):188–190
49. Zolfigol MA, Salehi P, Ghaderi A, Shiri M (2007) A catalytic and
green procedure for Friedlander quinoline synthesis in aqueous me-
dia. Catal Commun 8(8):1214–1218
68. Rai NP, Shashikanth S, Arunachalam PN (2009) Iodine-catalyzed
Aza-Diels–Alder reactions of aliphatic N-Arylaldimines. Synth
Commun 39(12):2125–2136
50. Ghorbani-Vaghei R, Akbari-Dadamahaleh S (2009) Poly (N-bro-
mo-N-ethylbenzene-1, 3-disulfonamide) and N, N, N′, N′-
tetrabromobenzene-1, 3-disulfonamide as efficient reagents for syn-
thesis of quinolines. Tetrahedron Lett 50(9):1055–1058
51. Vander Mierde H, Van Der Voort P, Verpoort F (2008) Base-
mediated synthesis of quinolines: an unexpected cyclization reac-
tion between 2-aminobenzylalcohol and ketones. Tetrahedron Lett
49(48):6893–6895
52. Vander Mierde H, Van Der Voort P, Verpoort F (2009) Fast and
convenient base-mediated synthesis of 3-substituted quinolines.
Tetrahedron Lett 50(2):201–203
53. Venkatesan H, Hocutt FM, Jones TK, Rabinowitz MH (2010) A
one-step synthesis of 2, 4-unsubstituted quinoline-3-carboxylic acid
esters from o-nitrobenzaldehydes. J Org Chem 75(10):3488–3491
54. Ryabukhin SV, Naumchik VS, Plaskon AS, Grygorenko OO,
Tolmachev AA (2011) 3-haloquinolines by friedlander reaction of
α-haloketones. J Org Chem 76(14):5774–5781
55. Rafiee E, Nejad FK, Joshaghani M (2011) Cs x H 3− x PW 12 O 40
heteropoly salts catalyzed quinoline synthesis via Friedländer reac-
tion. Chin Chem Lett 22(3):288–291
56. Denmark SE, Venkatraman S (2006) On the mechanism of the
Skraup-Doebner-von miller quinoline synthesis. J Org Chem
71(4):1668–1676
57. Wu YC, Liu L, Li HJ, Wang D, Chen YJ (2006) Skraup-Doebner-
von miller quinoline synthesis revisited: reversal of the
regiochemistry for γ-aryl-β, γ-unsaturated α-ketoesters. J Org
Chem 71(17):6592–6595
58. Vicente-García E, Catti F, Ramón R, Lavilla R (2010) Unsaturated
lactams: new inputs for Povarov-type multicomponent reactions.
Org Lett 12(4):860–863
59. Shindoh N, Tokuyama H, Takemoto Y, Takasu K (2008)
Auto-tandem catalysis in the synthesis of substituted quino-
lines from Aldimines and electron-rich olefins: Cascade
Povarov − Hydrogen-transfer reaction. J Org Chem 73(19):
7451–7456
60. Zhao YL, Zhang W, Wang S, Liu Q (2007) Ethynyl ketene-S, S-
acetals: the highly reactive electron-rich dienophiles and applica-
tions in the synthesis of 4-functionalized quinolines via a one-pot
three-component reaction. J Org Chem 72(13):4985–4988
61. Richter H, García Mancheño O (2011) TEMPO oxoammonium
salt-mediated dehydrogenative Povarov/oxidation tandem reaction
of N-alkyl anilines. Org Lett 13(22):6066–6069
62. Gong DH, Li JF, Yuan CY (2001) A new and facile synthesis of 6-
methyl-2-trifluoromethyl-4-(O, O-dialkyl) phosphoryl-quinoline.
Chin J Chem 19(12):1263–1267
63. Guchhait SK, Jadeja K, Madaan C (2009) A new process of multi-
component Povarov reaction–aerobic dehydrogenation: synthesis
of polysubstituted quinolines. Tetrahedron Lett 50(49):6861–6865
64. Povarov LS (1967) αβ-Unsaturated ethers and their analogues in
reactions of diene synthesis. Russ Chem Rev 36(9):656–670
65. Kouznetsov VV (2009) Recent synthetic developments in a pow-
erful imino Diels–Alder reaction (Povarov reaction): application to
69. Fery-Forgues S, Lavabre D (1999) Are fluorescence quantum
yields so tricky to measure? A demonstration using familiar statio-
nery products. J Chem Educ 76(9):1260
70. Lacerda V Jr, dos Santos DA, da Silva-Filho LC, Greco SJ, dos
Santos RB (2012) The growing impact of niobium in organic syn-
thesis and catalysis. Aldrichimica Acta 45(1):19
71. Andrade A, Santos GC, Silva-Filho LC (2015) Synthesis of quino-
line derivatives by multicomponent reaction using niobium
pentachloride as Lewis acid. J Heterocycl Chem 52(1):273–277
72. Zhang Y, Li P, Wang L (2011) Iron-catalyzed tandem reactions of
aldehydes, terminal alkynes, and primary amines as a strategy for
the synthesis of quinoline derivatives. J Heterocycl Chem 48(1):
153–157
73. Leardini R, Nanni D, Tundo A, Zanardi G, Ruggieri F (1992)
Annulation reactions with iron (III) chloride: oxidation of imines.
J Org Chem 57(6):1842–1848
74. Sarma R, Prajapati D (2008) Ionic liquid-an efficient recyclable
system for the synthesis of 2, 4-disubstituted quinolines via
Meyer-Schuster rearrangement. Synlett 2008(19):3001–3005
75. Anvar S, Mohammadpoor-Baltork I, Tangestaninejad S,
Moghadam M, Mirkhani V, Khosropour AR, Kia R (2012)
Efficient and environmentally-benign three-component synthesis
of quinolines and bis-quinolines catalyzed by recyclable potassium
dodecatungstocobaltate trihydrate under microwave irradiation.
RSC Adv 2(23):8713–8720
76. Lekhok KC, Prajapati D, Boruah RC (2008) Indium (III)
trifluoromethanesulfonate: an efficient reusable catalyst for the
alkynylation-cyclization of 2-aminoaryl ketones and synthesis of
2, 4-disubstituted quinolines. Synlett 2008(05):655–658
77. Kulkarni A, Török B (2010) Microwave-assisted multicomponent
domino cyclization–aromatization: an efficient approach for the
synthesis of substituted quinolines. Green Chem 12(5):875–878
78. Yao C, Qin B, Zhang H, Lu J, Wang D, Tu S (2012) One-pot
solvent-free synthesis of quinolines by C–H activation/C–C bond
formation catalyzed by recyclable iron (III) triflate. RSC Adv 2(9):
3759–3764
79. Das B, Jangili P, Kashanna J, Kumar RA (2011) Organic
reactions in water: a distinct approach for the synthesis of
quinoline derivatives starting directly from Nitroarenes.
Synthesis 2011(20):3267–3270
80. Zhang L, Wu B, Zhou Y, Xia J, Zhou S, Wang S (2013) Rare-earth
metal chlorides catalyzed one-pot syntheses of quinolines under
solvent-free microwave irradiation conditions. Chin J Chem
31(4):465–471
81. Busch M, Schmidt W (1929) Über die katalytische Hydrierung
organischer Halogenverbindungen. Berichte der deutschen
chemischen Gesellschaft (A and B Series) 62(9):2612–2620
82. Busch M, Weber W (1936) Über Kohlenstoffverkettungen bei der
katalytischen Hydrierung von Alkylhalogeniden. J Prakt Chem
146(1–4):1–55
83. Mosby W (1959) Notes-some 9, 10-Disubstituted Phenanthrenes. J
Org Chem 24(3):421–423

J Fluoresc
84. Rodrıguez JG, Lafuente A (2002) A new advanced method for
86. Hu J, Zhang CY (2013) Simple and accurate quantification of quan-
tum yield at the single-molecule/particle level. Anal Chem 85(4):
2000–2004
87. Pavia DL, Lampman GM, Kriz GS (2001) Introduction to spectros-
copy: a guide for students of organic chemistry, 3rd edn. Thomson
Learning Inc., Bellingham (USA)
́
heterogeneous catalysed dechlorination of 1, 2, 3-, 1, 2, 4-, and 1,
3, 5-trichlorobenzenes in hydrocarbon solvent. Tetrahedron Lett
43(52):9645–9647
85. Rodrıguez JG, Lafuente A (2002) A new advanced method for
heterogeneous catalysed dechlorination of polychlorinated biphe-
nyls (PCBs) in hydrocarbon solvent. Tetrahedron Lett 43(52):
9581–9583