A fluorescence study of new angular polycyclic blue light-emitting pyrazolo[3,4-h][1,6]naphthyridine and their Interaction with bovine serum albumin (BSA)

Article abstract of DOI:10.1007/s10895-011-0915-2

The blue light-emitting pyrazolo[3,4-h][1,6]naphthyridines has been synthesized by Friedl?nder condensation of 4-amino-3-(4-phenyl)-1-phenyl- 1H-pyrazolo[3,4-b]pyridine- 5-carbaldehyde (o-aminoaldehyde) 1 with different cyclic ketones and 1,3-diketones. The synthesized angular polycyclic naphthyridine derivatives were studied for Semiempirical, thermal, UV-vis and fluorescence spectroscopic properties on binding with bovin serum albumin (BSA). These fluorescence properties together with the neutral, hydrophobic nature of these compounds make these fluorophores good fluorescence probe for studying the micropolarity of proteins like BSA and in general the ligand-protein interactions. All of them displays bright absorption at 394 nm & emission in visible region (491 nm). Quantum yields of all synthesized compounds were calculated. Springer Science+Business Media, LLC 2011.

Full text of DOI:10.1007/s10895-011-0915-2

J Fluoresc (2011) 21:2037–2052
DOI 10.1007/s10895-011-0915-2
RAPID COMMUNICATION
A Fluorescence Study of New Angular Polycyclic Blue
Light-Emitting pyrazolo[3,4-h][1,6]naphthyridine
and their Interaction with Bovine Serum Albumin (BSA)
Sandeep R. Patil & Deepak P. Shelar & Ramhari V. Rote &
Madhukar N. Jachak
Received: 26 March 2011 /Accepted: 4 July 2011 /Published online: 14 July 2011
#
Springer Science+Business Media, LLC 2011
Abstract The blue light-emitting pyrazolo[3,4-h][1,6]naph-
thyridines has been synthesized by Friedländer condensation
of 4-amino-3-(4-phenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyri-
dine-5-carbaldehyde (o-aminoaldehyde) 1 with different
cyclic ketones and 1,3-diketones. The synthesized angular
polycyclic naphthyridine derivatives were studied for Semi-
empirical, thermal, UV–vis and fluorescence spectroscopic
properties on binding with bovin serum albumin (BSA).
These fluorescence properties together with the neutral,
hydrophobic nature of these compounds make these fluoro-
phores good fluorescence probe for studying the micropolarity
of proteins like BSA and in general the ligand-protein
interactions. All of them displays bright absorption at 394 nm
& emission in visible region (491 nm). Quantum yields of all
synthesized compounds were calculated.
materials are known to have extremely high fluorescence
quantum efficiencies in the visible spectrum [2, 3] including
the blue region, some approaching 100%. In this regard, they
are ideally suited for multicolor display applications. For full
color application red, green, and blue (RGB) emission are
required. An efficient blue emission is of particular interest
because other colors can be down converted from the blue
emission. There are a number of efficient blue dyes
developed in the past several years [4–10] some of which
possess reasonable or high glass transition temperature, Tg, a
property suggested to be desirable for morphological stability
reasons [11–13]. There is increasing interest in the develop-
ment of efficient fluorescent materials particularly those
emitting in the blue spectral region. These materials are
potential candidate for use in opto- or optoelectronic devices,
such as tuneable lasers and amplifers, optical fibres, switches
or modulators with a variety of applications in optical
communications, photonics, medicine, optical spectroscopy
and information displays, for example, organic electrolumi-
nescent devices [14–18]. From literature, it was observed
that the photophysical properties of pyrazolonaphthyridines
were little explored. Thus, suitable blue emitters with high
brightness along with good thermostability still remain to be
developed.
The early work on the use of fluorescent labeled antisera in
immunology was performed by Coons et al. (1942) and Coons
and Kaplan (1950). For a review up to 1954 see Coons (1954).
This defined technique permits selective “staining” of
antigens either in tissue section or isolated on a glass slide.
Recently, considerable attention has been focused on the study
of the interaction between small molecules (drugs) and
biological macromolecules (e.g. proteins), especially discus-
sing the thermodynamic quality, binding force quality, and
mechanism of interactions [19–21]. These studies play
crucial role in promoting research on proteins because they
.
.
Keywords HOMO-LUMO Absorption and emission
.
.
.
Quantum yield DSC TGA BSA
Introduction
Organic materials have previously been considered for the
fabrication of practical electroluminescent (EL) devices [1].
The primary reason is that a large number of organic
:
:
:
S. R. Patil D. P. Shelar R. V. Rote M. N. Jachak (*)
Organic Chemistry Research Center,
Department of Chemistry, K. T. H. M. College,
Gangapur Road,
Nashik 422 002 MS, India
e-mail: mnjachak@hotmail.com
:
:
:
S. R. Patil D. P. Shelar R. V. Rote M. N. Jachak
University of Pune,
Pune, India

2038
J Fluoresc (2011) 21:2037–2052
can provide useful information for study of pharmacological
and biological effects of drugs as well as conformational
changes of proteins caused by drugs. Serum albumin is one
of the most abundant proteins in circulatory system of a wide
variety of organisms and one of the most extensively studied
proteins at all [22, 23]. Perhaps, its most outstanding
property is the ability to bind a variety of ligands. It is well
known that many drugs bind to serum albumin and their
effectiveness depends on the binding ability [23, 24].
In our earlier communication, we have reported fluores-
cence properties of pyridine-3-carbonitriles [25], Spiro-
Oxazino-Quinoline derivatives [26] pyrazolopyrrolopyrimi-
dine (PPP) [27]. Recently we reported synthesis and effect of
specific solute-solvent interaction on fluorescence of pyr-
azolonaphthyridines using 1 (o-aminoaldehyde) [28]. In this
communication we extend work towards the synthesis of
new angular polycyclic blue light-emitting pyrazolo[3,4-h]
[1, 6]naphthyridine derivatives with (o-aminoaldehydes) 1
and studied their effect of binding interaction in aqueous
buffer and in bovine serum albumin (BSA) on fluorescence
properties, (a well-known protein responsible for transport of
a variety of ligands [29]) and also thermostabality of some
representative pyrazolonaphthyridine derivatives were stud-
ied with Semi-empirical calculations.
10a or 2/3-methylcyclohexanones 10b-c on refluxing in
ethanolic potassium hydroxide furnished 1-(4-chloro/bromo-
phenyl)-3-phenyl-3,7,8,9-tetrahydrocyclopenta[b]- pyrazolo
[3,4-h][1,6]naphthyridine 9a-b, 1-(4-chloro/bromo-phenyl)-
3-phenyl-7,8,9,10-tetra- hydro-3H-benzo[b]pyrazolo[3,4-h]
[1,6]naphthyridine 11a-b, and 1-(4-chloro/bromo-phenyl)-
9/10-methyl-3-phenyl-7,8,9,10-tetrahydro-3H-benzo[b]pyra-
zolo[3,4-h][1,6]naphthyridine 11c-f in 79%–85% yield re-
spectively. It was interesting to observe that when
cyclocondensation of ethyl 2-oxocyclohexane carboxylate
12 was performed with 1a or 1b resulted in the formation of
ethyl-1-(4-chloro/bromo-phenyl)-3-phenyl-7, 8, 9,10-tetrahy-
dro-3H-benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine-10-
carboxylate 13a-b without hydrolyzing ester functionality
in 12. However the reaction of o-aminoaldehyde 1a or 1b
with dimedone 14a and 5,5-dimethyl-1,3-dimedone 14b was
unsuccessful in ethanolic KOH, hence this cyclocondensa-
tion was achieved by heating the reaction mixture without
using any solvent at 140–150 °C, which offered 1-(4-chloro/
bromo-phenyl)-3-phenyl-7,8-dihydro-3H-benzo[b]pyrazolo
[3,4-h][1,6]naphthyridine −9-(10H)one 15a-b and 1-
(4-chloro/bromo-phenyl)-7,7-dimethyl-3-phenyl-7,8-dihy-
dro-3H-benzo[b]pyrazolo- [3,4-h][1,6]naphthyridine-9(10H)-
one 15c-d, respectively in 80–82% yield. Condensation of 1
with tetralone 16a, 6-methoxy-1-tetralone 16b, indanone
18a, 5,6-dimethoxy-1-indanone 18b, and cetralene 20 yield a
pentacyclic heterocycle, 1-(4-chloro/bromo-phenyl)-3-phe-
nyl-7,8-dihy- dro-3H-naphtho[1,2-b] pyrazolo[3,4-h][1,6]
naphthayridine 17a-b, 1-(4-chloro/bromo-phenyl)-10-
methoxy-3-phenyl-7,8-dihydro-3H-naphtho[1,2-b]pyrazolo
[3,4-h][1,6]naphthyridine 17c–d, 1-(4-chloro/bromo-phenyl)-
3-phenyl-3,7-dihydroindeno[1,2-b]pyrazolo[3,4-h][1,6]naph-
thyridine 19a-b, 1-(4-chloro/bromo-phenyl)-9,10-dimethoxy-
3-phenyl-3,7-dihydroindeno[1,2-b]pyrazolo- [3,4-h][1,6]-
naphthyridine 19c-d and 1-(4-chloro/bromo-phenyl)-8-(3,4-
dichlorophenyl)-3-phenyl-7,8-dihydro-3H-naphtho[1,2-b]
pyrazolo-[3,4-h][1,6]naphthyridine 21a–b, respectively in
excellent yield under similar reaction conditions. The
cycloconden- sation of N-substituted piperidones such as
N-methyl-piperidone 22a, N-acetyl-piperidone 22b and
N-BOC-piperidone 22c with 1 under similar reaction
condition smoothly yielded pyrazolo[3,4-h][1,6]- naphthyr-
idine derivatives 23a–f in 80%–85% yield (Scheme 2).
All these compounds were characterized by IR, 1H NMR,
Results and Discussion
An annulations reaction with heterocyclic aminoaldehyde
provides synthetic entry in to heterocyclic systems, fused to a
pyridine or pyrimidine nucleus with methylene active
compounds by Friedländer condensation reactions. The
required o-aminoaldehyde 1 was synthesized by multistep
reactions employed in our earlier paper [28]. Then, Fried-
länder condensation of o-aminoaldehyde 1 with active
methylenes compounds was performed. Thus, a mixture of
1a or 1b and α-active methylenes such as malononitrile,
acetylacetone 3a, ethylaceto- acetate 3b, acetone, ethyl-
cynoacetate 6a, diethylmalonate 6b, on refluxing in
ethanolic potassium hydroxide furnished pyrazolo[3,4-h]
[1,6]naphthyridines 2, 4, 5 and 7 respectively in good
yields (Scheme 1). Compounds 2, 4, 5 and 7 were
characterized by spectral and analytical methods.
The readily availability and wide choice of cyclic
ketenes, the ease of operation and the high yields obtained
make this heteroannulation sequence a versatile tool for
construction of multiple, fused ring structures. The use of
cyclic ketones such as derivatives of tetralone or indanone
allows rapid buildup of large polycyclic ring assemble with
o-aminoaldehydes. Thus, o-aminoaldehyde 1 was con-
densed with series of cyclic ketones to obtain the angular
polycyclic heterocyles. Thus, a mixture of 1a or 1b and
cyclic ketones such as cyclopentanone 8, cyclohexanone
mass, elemental analysis and some were characterized by 13
C
NMR; e.g. the IR spectrum of 23c shows carbonyl stretching
1
bands at 1715 cm−1. The H NMR spectrum shows a singlet
at 2.18 δ for –CH3 protons; it shows two triplets at 3.14 and
3.28 δ for four protons of piperidone ring, a singlet
corresponds to -CH2 protons of piperidone ring were
observed at 3.97δ. All aromatic protons showed expected
chemical shifts and splitting patterns which resembles with the
structure of 23c. The mass spectrum of 23c reveled a

J Fluoresc (2011) 21:2037–2052
2039
Scheme 1 Synthetic route of pyrazolo[3,4-h][1,6]naphthyridines
molecular ion peaks m/z at 498[M+] and at 500[M + 2]
respectively, due to presence of chlorine atom.
7.115 to 7.521 eV. From these calculations it is observed
that there is more overlappings between HOMOs and
LUMOs for compounds 17c–d, 19c–d and 21a–b which
show low gap value in the range 7.115–7.211 eV.
We observed blue light-emission of all synthesized
compounds with naked eyes under fluorescence wave
length (400–600 nm) in DMF; it was a fulfilling
experience, for instance, the blue emission by 23a and
23b shown in Fig. 1. Hence according to observed results
we decided to study photophysical properties of synthesized
compounds.
Thermal Properties
Organic compounds which used in OLEDs and in opto-
electronic applications should be thermally and chemically
stable [38]. Thermal analysis of representative compounds
23a, 23b by TGA and DSC were performed, which shows
their thermostability up to 350 °C. In Table 2, losses in
weight of these compounds observed during TGA in the
different temperature ranges are listed. It observed that, at
the temperature range 350–360 °C the loss in weight is
0.92% and 0.44% of 23a and 23b respectively which is
marginally constant. Where as loss in weight at the 450 °C
temperature is 51.50% and 55.56% respectively, which is in
good agreement to prove the decomposition temperature of
23a and 23b (Fig. 2)
Differential scanning calorimetry experiments of 23b
was performed, which should give information about
melting temperatures and decomposition temperatures and
in addition about the enthalpy as security hint. From DSC
experiment of compound 23b, it was observed that melting
onset temperature of about 258 °C is visible and enthalpy is
85.84 J/g. The decomposition of compound is shown by an
exothermic peak starting at 357.5 °C (Fig. 3). From TGA
and DSC analysis we conclude that the synthesized
pyrazolonaphthyridine derivatives are stable up to 350 °C
temperature.
Semi-empirical Study of Pyrazolo[3,4-h][1,6]
naphthyridines
The HOMO and LUMO of a molecule are usually
important characteristics for its chemical reactivity and for
biological activity [30–33]. The fluorophores which are
useful as Organic Light Emitting Diodes (OLEDs) should
fluoresces between 400 and 700 nm and should have an
electron hole gap up to 4 eV [34]. Prompted with these
report, we perform some computational calculations like
HOMO, LUMO energy and electron hole gap (HOMO-
LUMO energy separations) of synthesised pyrazolonaph-
thyridine derivatives using self-consistent field Hartree-
Fock(SCF-HF) method within the semi-empirical PM3
approximation [35, 36], as implemented in the MOPAC
program [37], and are listed in Table 1. The HOMO
energies for all these molecules are rather close to each
other, i.e., ranging between −8.435 eV and −8.850 eV,
while LUMO energies are ranging between −1.150 eV
and −1.439 eV (Table 1). Similarly, the HOMO-LUMO
energy separations were found to uniformly distribute from

2040
J Fluoresc (2011) 21:2037–2052
Scheme 2 Synthetic route of pyrazolo[3,4-h][1,6]naphthyridines
Spectral Properties
undertaken in polar aprotic solvent such as DMF and
spectral data are summarized in Table 3. Typical UV–vis
spectra of naphthyridines derivatives are found between ~360
and ~394 nm, (λab max) at room temperature and the
concentration of the solute were maintained at 10−3 M.
Among naphthyridine derivatives 17c–d, 19c–d & 21a–b are
significantly red-shifted, having shows absorption maxima
(λab max) at longer wavelength (388–394 nm). It is also
Absorption and Fluorescence Emission Properties
of Pyrazolonaphthyridine Derivatives in Organic
Solvent DMF
The absorption and fluorescence emission spectral prop-
erties of all pyrazolonaphthyridine derivatives were

J Fluoresc (2011) 21:2037–2052
2041
supported by low gap value of HOMO-LUMO energy levels
(Table 1). The compounds 17c–d & 19c shows absorption in
the range 390–394 nm and are may be good source in blue
LEDs.
The fluorescence maximums (λf max) of these compounds
were studied and their quantum yields (ϕf) were calculated
by standard literature procedures using quinine sulphate as
reference standard (ϕref=0.57 in 0.1 M H2SO4) [39–43] and
are listed in Table 3. All these compounds fluoresces
between ~434 nm and ~491 nm and have quantum yields
(ϕf) between 0.188 and 0.240. From Table 3, it was observed
that naphthyridine derivatives 21b, 23a, and 23b shows
higher emission maxima at 482 nm, 485 nm and 491 nm
than other derivatives with quantum yields (ϕf) 0.220, 0.221
and 0.240 respectively. The graphical representation of the
absorption (λab max) and fluorescence (λf max) spectra of
compounds 21b, 23a and 23b is shown in Fig. 4.
23a
23b
Fig. 1 Blue light emission under fluorescence lamp of compounds
23a and 23b
Table 1 The molecular electronic
Comp.
R
R1
R2
HOMO (eV)
LUMO (eV)
GAP (eV)
properties (HOMO-LUMO
energy, GAP) of the pyrazolo-
[3,4-h][1,6]naphthyridines
9a
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
Cl
Br
–
–
−8.636
−8.670
−8.628
−8.658
−8.651
−8.684
−8.635
−8.672
−8.850
−8.821
−8.626
−8.628
−8.803
−8.841
−8.665
−8.638
−8.492
−8.489
−8.648
−8.695
−8.435
−8.440
−8.647
−8.644
−8.642
−8.651
−8.627
−8.659
−8.617
−8.649
−1.168
−1.179
−1.165
−1.186
−1.152
−1.163
−1.150
−1.164
−1.352
−1.347
−1.166
−1.174
−1.355
−1.365
−1.370
−1.371
−1.309
−1.374
−1.382
−1.380
−1.314
−1.233
−1.439
−1.433
−1.398
−1.412
−1.384
−1.387
−1.340
−1.359
7.468
7.491
7.463
7.472
7.499
7.521
7.485
7.508
7.498
7.474
7.462
7.454
7.448
7.476
7.295
7.267
7.183
7.115
7.266
7.315
7.121
7.207
7.208
7.211
7.244
7.239
7.243
7.272
7.277
7.290
9b
–
–
11a
11b
11c
11d
11e
11f
H
H
H
H
CH3
H
CH3
H
H
CH3
H
CH3
13a
13b
15a
15b
15c
15d
17a
17b
17c
17d
19a
19b
19c
19d
21a
21b
23a
23b
23c
23d
23e
23f
–
–
–
–
H
H
H
H
CH3
CH3
CH3
CH3
H
H
H
H
OCH3
H
OCH3
H
H
H
H
H
OCH3
OCH3
–
OCH3
OCH3
–
–
–
–
–
–
–
–
–
CH3
CH3
COCH3
COCH3
COOC(CH3)3
COOC(CH3)3
GAP = ELUMO-EHOMO

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J Fluoresc (2011) 21:2037–2052
Table 2 Thermal analysis of 23a and 23b
Conclusion
Sr. no.
Temp.rang °C
loss (wt. mg)
Loss (wt%)
In summary, the heterocyclic o-aminoaldehyde 1 has been
utilized for Friedländer condensation with active methyl-
enes and cyclicketones to obtained tetracyclic/pentacyclic
heterocycles. This heteroannulation has been performed
under basic reaction condition. This transformation is
scalable and obtained products in high yields. Fluorescence
studies of pyrazolonaphthyridine derivatives have been
done in organic polar aprotic solvent DMF. All these
compounds emits blue light in visible region between 434
and 491 nm with quantum yield (ϕF) between 0.188 and
0.240. The interactions of pyrazolonaphthyridines with
BSA have been investigated by UV–vis absorption and
23a
23b
23a
23b
1
2
3
4
5
25–100
4.48
4.47
4.43
4.33
2.1
4.66
4.61
4.56
4.50
2.00
0.0
0.43
1.07
100–200
200–300
300–350
350–450
0.22
0.89
2.26
1.08
1.32
51.50
55.56
The Effect of BSA on Fluorescence Emission
of Pyrazolonaphthyridine Derivatives in Phosphate Buffer
fluorescence spectroscopy. The λf.
gets blue-shifted
max.
In order to examine the interaction of pyrazolonaphthyridine
with bovine serum albumin (BSA), the fluorescence titration
with BSAwere thus carried out in phosphate buffer of pH 7.4.
The absorption and fluorescent spectral data are collected in
Table 4 and λf. max. of 21b, 23a, 23b is graphically presented
in Fig. 5. A gradual increase in concentration of BSA in the
solution of naphthyridines in phosphate buffer results in an
enhancement of the fluorescence intensity and ϕf for all the
compounds. The λf max gets blue-shifted upon binding with
BSA, in general the fluorescence intensity of compounds
increased linearly with increasing BSA concentration. The
effect of increasing BSA concentration in the solution of
23b in phosphate buffer is shown in Fig. 6. Further, the
observed λf max remains insensitive to the change in BSA
concentration. The blue shift in the λf max suggests that the
polarities of the protein environments in which the pyrazo-
lonaphthyridine are located are less than the polarity of the
bulk phase. This shows the binding of the probes to a
hydrophobic site of the protein.
upon binding with BSA; however the fluorescence intensity
enhancement is linear with the increasing in BSA concen-
tration (23b). The pyrazolonaphthyridines are good fluo-
rescence probe, which can be use for studying the protein-
ligand interaction and their binding behavior. From TGA
and DSC experiment, we conclude that synthesized pyrazo-
lonaphthyridine derivatives are thermally stable up to 350 °C.
The efficient blue light emission and thermostability of
these compounds may have applications in opto-electronic
devices and are addition in the library of new heterocyclic
compounds.
Experimental
General
Bovine serum albumin (BSA) and Quinine sulphate was
purchased from HiMedi Laboratories Pvt. Ltd. Mumbai
(India) and Research-Lab Fin Chem. Industries, Mumbai
(India) respectively. All other chemicals, reagents and
solvents were obtained from LOBA Chemie. Pvt. Ltd.
Mumbai (India), Spectrochem, Mumbai (India) and E.
Merck (India). All AR-grade organic solvents were dried
and freshly distilled prior to use. The UV-grade solvents
were used for spectral studies. Melting points were
determined on a Gallenkamp melting point apparatus,
Mod. MFB595 in open capillary tubes and are uncorrected.
Fourier transform infrared (FTIR) spectra in KBr disk were
5
23a
4.5
23b
4
3.5
3
2.5
2
1
measured on a Shimadzu FTIR-408 spectrophotometer. H
NMR and 13C NMR spectra were recorded on a Varian XL-
300 MHz spectrometer using tetramethylsilane (TMS) as
internal standard and solvents are deuterio-chloroform
(CDCl3) and deuterio-dimethylsulphoxide (DMSO-d6).
Chemical shifts are reported in ppm from internal tetrame-
thylsilane standard and are given in δ-units. High-resolution
mass spectra are obtained with a Mat 112 Varian Mat
Bremen (70 eV) mass spectrometer. Elemental analyses are
1.5
1
0.5
0
0
50
100 150 200 250 300 350 400 450 500
Temperature
Fig. 2 TGA of compound 23a and 23b

J Fluoresc (2011) 21:2037–2052
Fig. 3 DSC of compound 23b
2043
performed on a Hosli CH-Analyzer and are within 0.3 of
the theoretical percentage. The absorption spectra were
measured using a Shimadzu UV-1601 UV–VIS spectropho-
tometer. The fluorescence spectra were recorded on a RF-
5301 PC spectrofluorophotometer by exciting the samples
at their absorption maximum (λabs. max.). Compounds for
UV and fluorescence measurements are dissolved in DMF,
UV and fluorescence scan are recorded from 200 to 600 nm.
The Фf relative to quinine sulphate in 1.0×10−3 mol L−1
H2SO4 (Фf=0.57) was measured at room temperature by
standard literature procedure (32–36). Both samples and
standard were excited at the same excitation wavelength
and the optical density (OD) of the standard and the sample
was adjusted to be nearly equal. For all electronic
spectroscopic studies (absorption, fluorescence excitation
and emission) 1.0×10−3 mol L−1 solutions of the com-
pounds were used. All reactions are monitored by thin layer
chromatography, carried out on 0.2 mm silica gel 60 F254
(Merck) plates using UV light (250 and 400 nm) and
Fluorescence light (400 and 600 nm) for detection. For
fluorescence quenching studies, the required amount of BSA
solution (in phosphate buffer) and the required amount of
pyrazolo[3,4-h][1,6]naphthyridines solution in dimethyl-
sulphoxide (DMSO) (1.0×10−4 mol L−1) were taken in a
5 ml volumetric flask. Since the pyrazolo[3,4-h][1,6]naph-
thyridines are sparingly soluble in water, their stock solutions
were prepared in DMSO, which is used as a solvent for
interaction studies of serum albumins [44].
was refluxed in ethanol (10 cm3) in presence of catalytic
amount of potassium hydroxide for 25–30 min. After
completion of reaction (TLC check), reaction mixture was
allowed to cool at room temperature. The separated solid
was collected by suction filtration, washed with cold
ethanol, dried and recrystallized from Ethanol: DMF (8:2)
to yield 2a–b in 82%–85% yield.
2-Amino-9-(4-chlorophenyl)-7-phyenyl-7H-pyrazolo[3,4-b]
[1,6]naphthyridine-3-carbonitrile (2a) Colorless prisms,
yield 0.340 g (85%); mp: 253–254 °C; IR (KBr): 3341,
1
3268, 2926, 2242, 1628, 1413 cm−1; H NMR (300 MHz,
DMSO-d6): δ, 7.28–7.56 (m, 5H, Ar-H), 7.72 (s, 2H, -NH2),
8.13 (s, 1H, Ar-H), 8.31 (d, 2H, J=8.4 Hz, Ar-H), 8.51
(s,1H, Ar-H), 8.90 (b, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR
(75 MHz, DMSO-d6): δ, 109.27, 110.39, 116.87, 118.34,
121.24 (2 C’s), 125.48, 127.51, 128.39 (2 C’s), 129.42
(2 C’s), 131.43, 132.23 (2 C’s), 134.14, 137.28, 142.31,
143.83, 148.02, 149.37, 158.96 ppm; ms: m/z (%) 396 [M+]
(100), 398 [M + 2] (27). Anal.Calcd. for C22H13N6Cl
(396.84): C, 66.58; H, 3.29; N, 21.18. Found: C, 66.60; H,
3.32; N, 21.20.
2-Amino-9-(4-bromophenyl)-7-phyenyl-7H-pyrazolo[3,4-b]
[1,6]naphthyridine-3-carbonitrile (2b) Colorless prisms,
0.365 g (82%); mp: 256–257 °C; IR (KBr): 3341, 3268,
1
2926, 2242, 1628, 1413 cm−1; H NHR (300 MHz, DMSO-
d6): δ, 7.28–7.56 (m, 5H, Ar-H), 7.72 (s, 2H, -NH2), 8.13
(s, 1H, Ar-H), 8.31 (d, 2H, J=8.4 Hz, Ar-H), 8.51 (s, 1H,
Ar-H), 8.90 (b, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR
(75 MHz, DMSO-d6): δ, 109.27, 110.39, 116.87, 118.34,
121.24 (2 C’s), 125.48, 127.51, 128.39 (2 C’s), 129.42
(2 C’s), 131.43, 132.23 (2 C’s), 134.14, 137.28, 142.31,
Synthesis
General Procedure for the Synthesis of Compounds 2a–b A
mixture of 1a–b (0.01 mol) and malononitrile (0.01 mol)

2044
J Fluoresc (2011) 21:2037–2052
Table 3 The Photophysical data for electronic absorption (λabs. max.),
fluorescence (λf. max.) and quantum yield (ϕF) of pyrazolo[3,4-h][1,6]
naphthyridines for 0.01 M Conc. at room temp in DMF
General Procedure for the Synthesis of Compounds 4a–d A
mixture of 1a–b (0.01 mol) and acetylacetone 3a, ethyl-
acetoacetate 3b (0.01 mol) were refluxed in ethanol
(10 cm3) in presence of catalytic amount of potassium
hydroxide for 25–30 min. after completion of reaction
(TLC check), reaction mixture was allowed to cool at room
temperature. The separated solid was collected by suction
filtration, washed with cold ethanol, dried and recrystallized
from Ethanol: DMF (8:2) to obtain compounds 4a–d in
79–84% yield.
Comp.
λAbs. (nm)
λf. max (nm)
Quantum yield (ϕf)
2a
326
337
353
361
346
354
349
355
370
357
360
358
355
354
357
343
357
354
356
354
355
369
363
356
345
348
376
381
390
394
382
377
393
388
383
369
357
349
355
371
358
366
434
451
454
467
465
468
452
461
434
448
442
463
445
449
444
447
447
451
450
451
463
469
452
463
471
469
453
461
457
468
447
464
458
472
473
482
485
491
459
463
455
469
0.189
0.197
0.198
0.201
0.198
0.202
0.196
0.197
0.188
0.191
0.192
0.198
0.188
0.189
0.194
0.188
0.190
0.188
0.189
0.190
0.193
0.200
0.194
0.201
0.212
0.206
0.190
0.198
0.196
0.208
0.189
0.202
0.212
0.216
0.214
0.220
0.221
0.240
0.196
0.192
0.188
0.198
2b
4a
4b
4c
4d
5a
1-(9-(4-Chlorophenyl)-2-methyl-7-phenyl-7H-pyrazolo[3,4-b]
[1,6]naphthyridine-3-yl)ethanone (4a) White solid, 0.334 g
(81%); mp: 247–248 °C; IR (KBr): 2966, 1715, 1618,
1,569 cm−1; 1H NMR (300 MHz, DMSO-d6): δ, 2.48
(s, 3H, -CH3), 2.51 (s, 3H, -CH3), 7.37–7.54 (m, 5H, Ar-H),
8.19 (s, 1H, Ar-H), 8.32 (d, 2H, J=8.6 Hz, Ar-H), 8.54
(s, 1H, Ar-H), 8.83 (d, 2H, J=8.6 Hz, Ar-H) ppm; ms: m/z
(%) 412 [M+] (98), 414 [M + 2] (29). Anal.Calcd. for
C24H17N4ClO (412.88): C, 69.81; H, 4.14; N, 13.57.
Found: C, 69.83; H, 4.17; N, 13.58.
5b
7a
7b
7c
7d
9a
9b
11a
11b
11c
11d
11e
11f
13a
13b
15a
15b
15c
15d
17a
17b
17c
17d
19a
19b
19c
19d
21a
21b
23a
23b
23c
23d
23e
23f
1-(9-(4-Bromophenyl)-2-methyl-7-phenyl-7H-pyrazolo[3,4-b]
[1,6]naphthyridine-3-yl)ethanone (4b) White solid, 0.362 g
(79%); mp: 250–251 °C; IR (KBr): 2966, 1715, 1618,
1569 cm−1; 1H NMR (300 MHz, DMSO-d6): δ, 2.48
(s, 3H, -CH3), 2.51 (s, 3H, -CH3), 7.37–7.54 (m, 5H, Ar-H),
8.19 (s, 1H, Ar-H), 8.32 (d, 2H, J=8.6 Hz, Ar-H), 8.54
(s, 1H, Ar-H), 8.83 (d, 2H, J=8.6 Hz, Ar-H) ppm; ms: m/z
(%) 457 [M+] (100), 459 [M + 2] (94). Anal.Calcd. for
C24H17N4BrO (457.33): C, 63.02; H, 3.74; N, 12.24. Found:
C, 63.04; H, 3.76; N, 12.26.
Ethyl-9-(4-chlorophenyl)-2-methyl-7-phenyl-7H-pyrazolo
[3,4-b][1,6]naphthyridine-3-carboxylate (4c) White solid,
0.375 g (84%); mp: 258–259 °C; IR (KBr): 2912, 1738,
1
1604,1522 cm−1; H NMR (300 MHz, DMSO-d6): δ, 1.24
(t, 3H, J=4.2 Hz), 2.25 (s, 3H, -CH3), 4.19 (q, 2H,
J=4.2 Hz), 7.36–7.52 (m, 5H, Ar-H), 8.13 (s, 1H, Ar-H),
8.31 (d, 2H, J=8.4 Hz, Ar-H), 8.56 (s, 1H, Ar-H), 8.89
(d, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR (75 MHz, DMSO-
d6): δ, 16.23, 21.34, 61.91, 69.03, 108.47, 120.39, 121.44
(2 C’s), 125.32, 127.43, 128.97 (2 C’s), 129.32 (2 C’s),
131.41, 132.33 (2 C’s), 133.66, 136.70, 142.16, 146.52,
147.92, 148.61, 150.43, 163.61 ppm; ms: m/z (%) 442 [M+]
(100), 444 [M + 2] (28). Anal.Calcd. for C25H19N4ClO2
(442.91): C, 67.79; H, 4.31; N, 12.64. Found: C, 67.81; H,
4.30; N, 12.68.
143.83, 148.02, 149.37, 158.96 ppm; ms: m/z (%) 441
[M+] (94) 443 [M + 2] (91). Anal.Calcd. for C22H13N6Cl
(396.84): C, 66.58; H, 3.29; N, 21.18. Found: C, 66.60; H,
3.32; N, 21.20.
Ethyl-9-(4-bromophenyl)-2-methyl-7-phenyl-7H-pyrazolo
[3,4-b][1,6]naphthyridine-3-carboxylate (4 d) Colorless
prisms, 0.392 g (80%); mp: 257–258 °C; IR (KBr): 2912,
1
1738, 1604,1522 cm−1; H NMR (300 MHz, DMSO-d6): δ,

J Fluoresc (2011) 21:2037–2052
Fig. 4 The absorption (λab max
2045
)
and fluorescence (λf max) spectra
(λext=380 nm) of compounds
21b, 23a and 23b respectively
1.24 (t, 3H, J=4.2 Hz), 2.25 (s, 3H, -CH3), 4.19 (q, 2H,
J=4.2 Hz), 7.36–7.52 (m, 5H, Ar-H), 8.13 (s, 1H, Ar-H),
8.31 (d, 2H, J=8.4 Hz, Ar-H), 8.56 (s, 1H, Ar-H), 8.89
(d, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR (75 MHz, DMSO-
d6): δ, 16.23, 21.34, 61.91, 69.03, 108.47, 120.39, 121.44
(2 C’s), 125.32, 127.43, 128.97 (2 C’s), 129.32 (2 C’s),
131.41, 132.33 (2 C’s), 133.66, 136.70, 142.16, 146.52,
147.92, 148.61, 150.43, 163.61 ppm; ms: m/z (%) 487 [M+]
(100), 489 [M + 2] (96). Anal. Calcd. For C25H19N4BrO2
(487.36): C, 61.60; H, 3.92; N, 11.49. Found: C, 61.64; H,
3.93; N, 11.52.
reflux for 25–30 min (TLC check). The mixture was
allowed to cool at room temperature. The separated solid
was collected by suction filtration, washed with cold
ethanol, dried and recrystallized from Ethanol: DMF (9:1)
to furnish compounds 5a–b in 82% yield.
9-(4-chlorophenyl)-2-methyl-7-phenyl-7H-pyrazolo[3,4-b]
[1,6]naphthyridine (5a) Colorless solid, 0.305 g (82%); mp:
1
177–178 °C; IR (KBr): 2929, 1622, 1508, 1423 cm−1; H
NMR (300 MHz, CDCl3): δ, 2.82 (s, 3H, CH3), 7.37 (d, 1H,
J=7.4 Hz, Ar-H), 7.35–7.58 (m, 5H, Ar-H), 8.21 (d, 1H,
J=7.4 Hz, Ar-H), 8.26 (d, 2H, J=8.4 Hz, Ar-H), 8.54 (d, 2H,
J=8.4 Hz, Ar-H), 8.82 (s, 1H, Ar-H) ppm; ms: m/z (%) 370
[M+] (100), 372 [M + 2] (31). Anal. Calcd. for C22H15N4Cl
(370.84): C, 71.24; H, 4.07; N, 15.10. Found: C, 71.27; H,
4.09; N, 15.12.
General Procedure for the Synthesis of Compounds 5a–b A
mixture of 1a–b (0.01 mol) and acetone (0.01 mol) in
ethanolic potassium hydroxide solution (10 cm3, 2%) were
Table 4 Absorption maximum (λabs. max.), fluorescence emission
maximum (λf. max.) and fluorescence quantum yield (ϕF) of pyrazolo
[3,4-h][1,6]naphthyridine (in phosphate buffer (pH, 7.4) and BSA
9-(4-Bromophenyl)-2-methyl-7-phenyl-7H-pyrazolo[3,4-b]
[1,6]naphthyridine (5b) Colorless solid, 0.342 g (82%);
mp: 180–181 °C; IR (KBr): 2929, 1622, 1508, 1423 cm−1;
1H NMR (300 MHz, CDCl3): δ, 2.82 (s, 3H, CH3), 7.37
(d, 1H, J=7.4 Hz, Ar-H), 7.35–7.58 (m, 5H, Ar-H), 8.21
(d, 1H, J=7.4 Hz, Ar-H), 8.26 (d, 2H, J=8.4 Hz, Ar-H),
8.54 (d, 2H, J=8.4 Hz, Ar-H), 8.82 (s, 1H, Ar-H) ppm; ms: m/z
(%) 415 [M+] (100), 417 [M + 2] (93). Anal. Calcd. for
C22H15N4Br (415.30): C, 63.62; H, 3.63; N, 13.48. Found: C,
63.65; H, 3.64; N, 13.49.
(5.0×10−6 mol L−1
)
Compound
λabs. max. (nm)
λf. max. (nm)
ϕF ( 0.002)
Buffer
BSA
Buffer
BSA
Buffer
BSA
4d
318
316
319
327
333
977
369
352
339
322
320
319
322
325
329
379
371
355
341
325
473
460
442
455
448
454
449
463
467
472
417
404
398
418
409
416
424
427
433
440
0.181
0.172
0.169
0.190
0.179
0.188
0.214
0.223
0.242
0.257
0.210
0.204
0.201
0.213
0.209
0.224
0.251
0.267
0.277
0.287
7d
11f
13b
15d
17d
19d
21b
23a
23b
General Procedure for the Synthesis of Compounds 7a–d A
mixture of 1a–b (0.01 mol) and ethylcynoacetate 6a,
diethylmalonate 6b (0.01 mol) were refluxed in ethanol
(10 cm3) in presence of catalytic amount of potassium
hydroxide for 25–30 min. after completion of reaction
(TLC check), reaction mixture was allowed to cool at room
temperature. The separated solid was collected by suction

2046
J Fluoresc (2011) 21:2037–2052
Fig. 5 Comparative fluorescence
(λf Max.) spectra (λext=350 nm)
of 21b, 23a, and 23b: A] In
Phosphate Buffer, B] In BSA
filtration, washed with cold ethanol, dried and recrystallized
from Ethanol: DMF (9:1) to obtain compounds 7a–d in
78%–82% yield.
C22H12N5ClO (397.83): C, 66.41; H, 3.03; N, 17.59. Found:
C, 66.44; H, 3.07; N, 17.61.
9-(4-Bromophenyl)-2,7-dihydro-2-oxo-7-phenyl-7H-
pyrazolo[3,4-b][1,6]naphthyridine-3-carbonitrile (7b)
Colorless solid, 0.347 g (78%); mp: 264–265 °C; IR (KBr):
3412, 2922, 2212, 1672, 1603, 1406 cm−1; 1H NMR
(300 MHz, DMSO-d6): δ, 7.38–7.54 (m, 5H, Ar-H), 8.19
(d, 2H, J=8.2 Hz, Ar-H), 8.28 (s, 1H, -NH), 8.64 (d, 2H,
J=8.2 Hz, Ar-H), 8.74 (s, 1H, Ar-H), 8.87 (s, 1H, Ar-H) ppm;
13C NMR (75 MHz, DMSO-d6): δ, 106.32, 108.71, 114.71,
115.24, 118.81, 121.35 (2 C’s), 126.44, 128.91 (2 C’s),
129.52 (2 C’s), 131.26, 132.17 (2 C’s), 135.12, 139.93,
147.35, 149.41, 150.90, 152.33, 169.66 ppm; ms: m/z (%)
442 [M+] (100), 444 [M + 2] (95). Anal. Calcd. for
C22H12N5BrO (442.28): C, 59.74; H, 2.72; N, 15.82. Found:
C, 59.76; H, 2.75; N, 15.84.
9-(4-Chlorophenyl)-2,7-dihydro-2-oxo-7-phenyl-7H-pyrazolo
[3,4-b][1,6]naphthyridine-3-carbonitrile (7a) Colorless
solid, 0.314 g (79%); mp: 261–262 °C; IR (KBr): 3412,
1
2922, 2212, 1672, 1603, 1406, cm−1; H NMR (300 MHz,
DMSO-d6): δ, 7.38–7.54 (m, 5H, Ar-H), 8.19 (d, 2H,
J=8.2 Hz, Ar-H), 8.28 (s, 1H, -NH), 8.64 (d, 2H,
J=8.2 Hz, Ar-H), 8.74 (s, 1H, Ar-H), 8.87 (s, 1H, Ar-H)
ppm; 13C NMR (75 MHz, DMSO-d6): δ, 106.32, 108.71,
114.71, 115.24, 118.81, 121.35 (2 C’s), 126.44, 128.9 (2 C’s),
129.52 (2 C’s), 131.26, 132.17 (2 C’s), 135.12, 139.93,
147.35, 149.41, 150.90, 152.33, 169.66 ppm; ms: m/z (%)
397 [M+] (100), 399 [M + 2] (33). Anal. Calcd. for
Ethyl-9-(4-chlorophenyl)-2,7-dihydro-2-oxo-7-phenyl-7H-
pyrazolo[3,4-b][1,6]naphthyridine-3-carboxylate (7c) Col-
orless solid, 0.367 g (82%); mp: 244–445 °C; IR (KBr):
1
3369, 3012, 2968, 1741, 1669, 1598, 1420 cm−1; H NMR
(300 MHz, DMSO-d6): δ, 1.42 (t, 3H, J=7.2 Hz, CH3),
4.49 (q, 2H, J=7.2 Hz, CH2), 7.38–7.52 (m, 5H, Ar-H),
8.28 (s, 1H, NH), 8.31 (d, 2H, J=8.4 Hz, Ar-H), 8.51(s, 1H,
Ar-H), 8.84 (s, 1H, Ar-H), 9.01 (d, 2H, J=8.4 Hz, Ar-H)
ppm; ms: m/z (%) 444 [M+] (100), 446 [M + 2] (27). Anal.
calcd. for C24H17N4O3Cl (444.88): C, 64.79; H, 3.84; N,
12.58. Found: C, 64.81; H, 3.86; N, 12.61.
Ethyl-9-(4-bromophenyl)-2,7-dihydro-2-oxo-7-phenyl-7H-
pyrazolo[3,4-b][1,6]naphthyridine-3-carboxylate (7d) Col-
orless solid, 0.389 g (79%); mp: 243–244 °C; IR (KBr):
Fig. 6 Fluorescence emission spectra (λext=350 nm) of 23b with
increasing BSA Concentration; curves a-d correspond to [BSA] 1.0,
2.0, 3.0, and 4.0 (×10−6 mol L−1), respectively
1
3369, 3012, 2968, 1741, 1669, 1598, 1420 cm−1; H NMR

J Fluoresc (2011) 21:2037–2052
2047
(300 MHz, DMSO-d6): δ, 1.42 (t, 3H, J=7.2 Hz, CH3),
4.49 (q, 2H, J=7.2 Hz, CH2), 7.38–7.52 (m, 5H, Ar-H),
8.28 (s, 1H, NH), 8.31 (d, 2H, J=8.4 Hz, Ar-H), 8.51 (s,
1H, Ar-H), 8.84 (s, 1H, Ar-H), 9.01 (d, 2H, J=8.4 Hz,
Ar-H) ppm; ms: m/z (%) 489 [M+] (100), 491 [M + 2] (96).
Anal. calcd. for C24H17N4O3Br (489.33): C, 58.90; H, 3.49;
N, 11.44. Found: C, 58.93; H, 3.52; N, 11.47.
prisms, 0.345 g (84%); mp: 147–148 °C; IR (KBr): 3015,
2942, 1622, 1560, 1442 cm−1; 1H NMR (300 MHz,
CDCl3): δ, 1.79 (m, 2H, CH2), 1.94 (m, 2H, CH2), 2.59
(t, 2H, J=6.0 Hz, CH2), 2.94 (t, 2H, CH2), 7.34–7.52 (m,
5H, Ar-H), 8.17 (s, 1H, Ar-H), 8.35 (d, 2H, J=8.6 Hz, Ar-H),
8.49 (s, 1H, Ar-H), 8.89 (b, 2H, J=8.6 Hz, Ar-H) ppm; ms: m/z
(%) 410 [M+] (100), 412 [M + 2] (29). Anal. Calcd. For
C25H19N4Cl (410.91): C, 73.07; H, 4.65; N, 13.62. Found: C,
73.10; H, 4.66; N, 13.66.
General Procedure for the Synthesis of Compounds 9a–b A
mixture of 1a–b (0.01 mol) and cyclopentanone
8 (0.01 mol) in ethanolic potassium hydroxide solution
(10 cm3, 2%) was refluxed for 25–30 min. after completion
of reaction (TLC check), reaction mixture was allowed to
cool at room temperature. The separated solid was collected
by suction filtration, washed with cold ethanol, dried and
recrystallized from Ethanol: DMF (9:1) to obtain compounds
9a–b in 79–80% yield.
1-(4-Bromophenyl)-3-phenyl-7,8,9,10-tetrahydro-3H-benzo
[b]pyrazolo[3,4-h][1,6]- naphthyridine (11b) Colorless
prisms, 0.361 g (79%); mp: 145–146 °C; IR (KBr): 3015,
2942, 1622, 1560, 1442 cm−1; 1H NMR (300 MHz,
CDCl3): δ, 1.79 (m, 2H, CH2), 1.94 (m, 2H, CH2), 2.59
(t, 2H, J=6.0 Hz, CH2), 2.94 (t, 2H, CH2), 7.34–7.52
(m, 5H, Ar-H), 8.17 (s, 1H, Ar-H), 8.35 (d, 2H, J=8.6 Hz,
Ar-H), 8.49 (s, 1H, Ar-H), 8.89 (b, 2H, J=8.6 Hz, Ar-H)
ppm; ms: m/z (%) 455 [M+] (96), 457 [M + 2] (89). Anal.
Calcd. For C25H19N4Br (455.36): C, 65.93; H, 4.20; N,
12.29. Found: C, 65.96; H, 4.22; N, 12.33.
1-(4-Chlorophenyl)-3-phenyl-3,7,8,9-tetrahydrocyclopenta
[b]pyrazolo[3,4-h][1,6]naphthyridine (9a) Colorless solid,
0.314 g (79%); mp: 188–189 °C; IR (KBr): 2942, 2914,
1621, 1562, 1437 cm−1; 1H NMR (300 MHz, CDCl3): δ, 2.42
(m, 2H, CH2), 3.08 (t, 2H, J=6.2 Hz, CH2), 3.19 (t, 2H,
J=7.8 Hz, CH2), 7.33–7.52 (m, 5H, Ar-H), 8.29 (s, 1H, Ar-H),
8.37 (d, 2H, J=8.4 Hz, Ar-H), 8.55 (s, 1H, Ar-H), 9.04
(d, 2H, J=8.4 Hz, Ar-H) ppm; ms: m/z (%) 396 [M+] (100),
398 [M + 2] (29). Anal. Calcd. For C24H17N4Cl (396.88): C,
72.62; H, 4.31; N, 14.11. Found: C, 72.65; H, 4.33; N, 14.14.
1-(4-Chlorophenyl)-10-methyl-3-phenyl-7,8,9,10-tetrahydro-
3H-benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine (11c) Col-
orless prisms, 0.344 g (81%); mp: 138–139 °C; IR (KBr):
1
3015, 2942, 1622, 1560, 1442 cm−1; H NMR (300 MHz,
CDCl3): δ, 1.32 (d, 3H, J=5.6 Hz, CH3), 1.81 (m, 1H, CH),
1.87 (m, 1H, CH), 1.92 (m, 1H, CH), 2.07 (m, 1H, CH),
2.54 (m, 1H, CH), 2.61 (m, 1H, CH), 2.84 (m, 1H, CH),
7.37–7.55 (m, 5H, Ar-H), 8.29 (s, 1H, Ar-H), 8.33 (d, 2H,
J=8.4 Hz, Ar-H), 8.52 (s, 1H, Ar-H), 9.07 (d, 2H, J=
8.4 Hz, Ar-H) ppm; 13C NMR (75 MHz, CDCl3): δ, 22.07,
24.24, 31.33, 31.96, 32.64, 107.81, 121.11 (2 C’s), 123.31,
127.24, 128.91 (2 C’s), 129.77 (2 C’s), 131.17, 132.01
(2 C’s), 133.67, 134.49, 134.94, 139.97, 142.87, 147.97,
149.60, 150.50, 162.32 ppm; ms: m/z (%) 424 [M+] (100),
426 [M + 2] (28). Anal. Calcd. For C26H21N4Cl (424.94):
C, 73.48; H, 4.97; N, 13.17. Found: C, 73.51; H, 4.99; N,
13.20.
1-(4-Bromophenyl)-3-phenyl-3,7,8,9-tetrahydrocyclopenta
[b]pyrazolo[3,4-h][1,6]naphthyridine (9b) Colorless solid,
0.354 g (80%); mp: 182–183 °C; IR (KBr): 2942, 2914,
1
1621, 1562, 1437 cm−1; H NMR (300 MHz, CDCl3): δ,
2.42 (m, 2H, CH2), 3.08 (t, 2H, J=6.2 Hz, CH2), 3.19
(t, 2H, J=7.8 Hz, CH2), 7.33–7.52 (m, 5H, Ar-H), 8.29
(s, 1H, Ar-H), 8.37(d, 2H, J=8.4 Hz, Ar-H), 8.55 (s, 1H,
Ar-H), 9.04 (d, 2H, J=8.4 Hz, Ar-H) ppm; ms: m/z (%) 441
[M+] (100), 443 [M + 2] (96). Anal. Calcd. For C24H17N4Br
(441.33): C, 65.31; H, 3.87; N, 12.68. Found: C, 65.35; H,
3.90; N, 12.71.
1-(4-Bromophenyl)-10-methyl-3-phenyl-7,8,9,10-tetrahydro-
3H-benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine (11 d) Col-
orless solid, 0.377 g (80%); mp: 142–143 °C; IR (KBr):
General Procedure for the Synthesis of Compounds 11a–
f A mixture of 1a–b (0.01 mol), and cyclohexanone 10a and
2/3-methylcyclohexanones 10b–c (0.01 mol) in ethanolic
potassium hydroxide solution (10 cm3, 2%) was refluxed for
25–30 min, after completion of reaction (TLC check), reaction
mixture was allowed to cool at room temperature. The
separated solid was collected by suction filtration, washed
with cold ethanol, dried and recrystallized from Ethanol:
DMF (8:2) to obtain compounds 11a–f in 79%–84% yield.
1
3015, 2942, 1622, 1560, 1442 cm−1; H NMR (300 MHz,
CDCl3): δ, 1.32 (d, 3H, J=5.6 Hz, CH3), 1.81 (m, 1H, CH),
1.87 (m, 1H, CH), 1.92 (m, 1H, CH), 2.07 (m, 1H, CH),
2.54 (m, 1H, CH), 2.61(m, 1H, CH), 2.84 (m, 1H, CH),
7.37–7.55 (m, 5H, Ar-H), 8.29 (s, 1H, Ar-H), 8.33 (d, 2H,
J=8.4 Hz, Ar-H), 8.52 (s, 1H, Ar-H), 9.07 (d, 2H, J=
8.4 Hz, Ar-H) ppm; 13C NMR(75 MHz, CDCl3): δ, 22.07,
24.24, 31.33, 31.96, 32.64, 107.81, 121.11 (2Cs), 123.31,
127.24, 128.91 (2Cs), 129.77 (2Cs), 131.17, 132.01 (2Cs),
133.67, 134.49, 134.94, 139.97, 142.87, 147.97, 149.60,
1-(4-Chlorophenyl)-3-phenyl-7,8,9,10-tetrahydro-3H-benzo
[b]pyrazolo[3,4-h][1,6]- naphthyridine (11a) Colorless

2048
J Fluoresc (2011) 21:2037–2052
150.50, 162.32 ppm; ms: m/z (%) 469 [M+] (96), 471 [M + 2]
(92). Anal. Calcd. For C26H21N4Br(469.39): C, 66.52; H,
4.50; N, 11.93. Found: C, 66.54; H, 4.56; N, 11.96.
69.62; H, 4.79; N, 11.59. Found: C, 69.64; H, 4.84; N,
11.63.
Ethyl-1-(4-bromophenyl)-3-phenyl-7,8,9,10-tetrahydro-
3H-benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine-10-
carboxylate (13b) white solid, 0.441 g (83%); mp: 166–
167 °C; IR (KBr): 3035, 2912, 1741, 1612, 1522,
1-(4-Chlorophenyl)-9-methyl-3-phenyl-7,8,9,10-tetrahydro-
3H-benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine (11e)
Colorless solid, 0.347 g (81%); mp: 146–147 °C; IR (KBr):
1
1
3015, 2942, 1622, 1560, 1442 cm−1; H NMR (300 MHz,
1032 cm−1; H NMR (300 MHz, CDCl3): δ, 1.84 (t, 3H,
CDCl3): δ, 1.17 (d, 3H, J=6.2 Hz, CH3), 1.56 (m, 1H, CH),
1.72 (m, 1H, CH), 2.12 (m, 1H, CH), 2.58 (m, 1H, CH),
2.67 (m, 1H, CH), 2.88 (m, 1H, CH), 2.94 (m, 1H, CH),
7.34–7.51 (m, 5H, Ar-H), 8.25 (s, 1H, Ar-H), 8.37 (d, 2H,
J=8.4 Hz, Ar-H), 8.56 (s, 1H, Ar-H), 9.02 (d, 2H, J=8.4 Hz,
Ar-H) ppm; ms: m/z (%) 424 [M+] (100), 426 [M + 2] (29).
Anal. Calcd. For C26H21N4Cl (424.94): C, 73.48; H, 4.97; N,
13.17. Found: C, 73.51; H, 4.99; N, 13.20.
J=6.1 Hz, CH2), 1.90 (m, 1H, CH), 2.09(m, 1H, CH), 2.84
(m, 1H, CH), 2.96 (m, 1H, CH), 3.14 (m, 1H, CH), 3.21
(m, 1H, CH), 3.41 (t, 1H, J=6.3 & 4.1 Hz, Ar-H), 4.21
(q, 2H, J=6.1 Hz, CH2), 7.33–7.51 (m, 5H, Ar-H), 8.34
(d, 2H, J=8.4 Hz, Ar-H), 8.53 (s, 1H, Ar-H), 8.86 (s, 1H, Ar-
H), 9.05 (d, 2H, J=8.4 Hz, Ar-H) ppm; ms: m/z (%) 527 [M+]
(100), 529 [M + 2] (94). Anal. Calcd. For C28H23N4O2Br
(527.43): C, 63.75; H, 4.39; N, 10.61. Found: C, 63.77; H,
4.42; N, 10.63.
1-(4-Bromophenyl)-9-methyl-3-phenyl-7,8,9,10-tetrahydro-
3H-benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine (11f)
Colorless prisms, 0.372 g (79%); mp: 150–151 °C; IR
(KBr): 3015, 2942, 1622, 1560, 1442 cm−1; 1H NMR
(300 MHz, CDCl3): δ, 1.17 (d, 3H, J=6.2 Hz, CH3), 1.56
(m, 1H, CH), 1.72 (m, 1H, CH), 2.12 (m, 1H, CH), 2.58
(m, 1H, CH), 2.67 (m, 1H, CH), 2.88 (m, 1H, CH), 2.94
(m, 1H, CH), 7.34–7.51 (m, 5H, Ar-H), 8.25 (s, 1H, Ar-H),
8.37 (d, 2H, J=8.4 Hz, Ar-H), 8.56 (s, 1H, Ar-H), 9.02
(d, 2H, J=8.4 Hz, Ar-H) ppm; ms: m/z (%) 469 [M+] (98),
471 [M + 2] (83). Anal. Calcd. For C26H21N4Br (469.39):
C, 66.52; H, 4.50; N, 11.93. Found: C, 66.54; H, 4.56; N,
11.96.
General Procedure for the synthesis of compounds 15a–d A
mixture of 1 (0.01 mol) and dimedone 14a, 5,5-dimethyl-
1,3-dimedone 14b (0.01 mol) was heated at 140–150 °C for
30–35 min. the solid obtained on cooling was stirred in
methanol (10 cm3) for 15 min. the solid obtain was
collected by filtration and washed with cold ethanol
(5 cm3), dried to obtain 15a–d in 80%–82% yield.
1-(4-Chlorophenyl)-3-phenyl-7,8-dihydro-3H-benzo[b]
pyrazolo[3,4-h][1,6]naphthyridine-9(10H)-one (15a) Color-
less prisms, 0.341 g (80%); mp: 224–225 °C; IR (KBr):
1
3004, 2958, 1704, 1602, 1445 cm−1; H NMR (300 MHz,
CDCl3): δ, 2.64 (t, 2H, J=5.4 Hz, CH2), 2.82 (t, 2H,
J=5.4 Hz, CH2), 3.44 (s, 2H, CH2), 7.33–7.51 (m, 5H, Ar-H),
8.21 (s, 1H, Ar-H), 8.36 (d, 2H, J=8.6 Hz, Ar-H), 8.52
(s, 1H, Ar-H), 8.89 (d, 2H, J=8.6 Hz, Ar-H) ppm; ms: m/z
(%) 424 [M+] (100), 426 [M + 2] (32). Anal. Calcd. For
C25H17N4OCl (424.89): C, 70.67; H, 4.02; N, 13.18. Found:
C, 70.69; H, 4.06; N, 13.23.
General Procedure for the synthesis of compounds
13a–b A mixture of 1a–b (0.01 mol) and ethyl 2-
oxocyclohexane carboxylate 12 (0.01 mol) was refluxed
in ethanol (10 cm3) in presence of catalytic amount of
potassium hydroxide for 25–30 min (TLC check). The
mixture was then allowed to cool at room temperature and
the separated solid was collected by suction filtration,
washed with ethanol and dried, to obtain 13a–b in 82%–
83% yield.
1-(4-Bromophenyl)-3-phenyl-7,8-dihydro-3H-benzo[b]
pyrazolo[3,4-h][1,6]naphthyridine-9(10H)-one (15b) Color-
less prisms, 0.380 g (81%); mp: 229–230 °C; IR (KBr):
1
Ethyl-1-(4-chlorophenyl)-3-phenyl-7,8,9,10-tetrahydro-3H-
benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine-10-carboxylate
(13a) White solid, 0.396 g (82%); mp: 161–162 °C; IR
(KBr): 3035, 2912, 1741, 1612, 1522, 1032 cm−1; 1H NMR
(300 MHz, CDCl3): δ, 1.84 (t, 3H, J=6.1 Hz, CH2), 1.90
(m, 1H, CH), 2.09 (m, 1H, CH), 2.84 (m, 1H, CH), 2.96
(m, 1H, CH), 3.14 (m, 1H, CH), 3.21 (m, 1H, CH), 3.41 (t,
1H, J=6.3 & 4.1 Hz, Ar-H), 4.21 (q, 2H, J=6.1 Hz, CH2),
7.33–7.51 (m, 5H, Ar-H), 8.34 (d, 2H, J=8.4 Hz, Ar-H),
8.53 (s, 1H, Ar-H), 8.86 (s, 1H, Ar-H), 9.05 (d, 2H,
J=8.4 Hz, Ar-H) ppm; ms: m/z (%) 482 [M+] (100), 484
[M + 2] (29). Anal. Calcd. For C28H23N4O2Cl (482.97): C,
3004, 2958, 1704, 1602, 1445 cm−1; H NMR (300 MHz,
CDCl3): δ, 2.64 (t, 2H, J=5.4 Hz, CH2), 2.82 (t, 2H,
J=5.4 Hz, CH2), 3.44 (s, 2H, CH2), 7.33–7.51 (m, 5H, Ar-H),
8.21 (s, 1H, Ar-H), 8.36 (d, 2H, J=8.6 Hz, Ar-H), 8.52
(s, 1H, Ar-H), 8.89 (d, 2H, J=8.6 Hz, Ar-H) ppm; ms: m/z
(%) 469 [M+] (100), 471 [M + 2] (93). Anal. Calcd. For
C25H17N4OBr (469.34): C, 63.97; H, 3.65; N, 11.93. Found:
C, 63.99; H, 3.67; N, 11.96.
1-(4-Chlorophenyl)-7,7-dimethyl-3-phenyl-7,8-dihydro-3H-
benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine-9(10H)-one
(15c) Colorless prisms, 0.371 g (82%); mp: 242–243 °C;

J Fluoresc (2011) 21:2037–2052
2049
IR (KBr): 3004, 2958, 1704, 1602, 1445 cm−1; H NMR
(300 MHz, CDCl3): δ, 1.14 (s, 6H, (CH3)2), 3.12 (s, 2H,
CH2), 3.74 (s, 2H, CH2), 7.35–7.52 (m, 5H, Ar-H), 8.27
(s, 1H, Ar-H), 8.39 (d, 2H, J=8.6 Hz, Ar-H), 8.54 (s, 1H,
Ar-H), 9.01 (d, 2H, J=8.6 Hz, Ar-H) ppm; 13C NMR
(75 MHz, CDCl3): δ, 29.93, 29.93, 39.43, 46.36, 58.44,
109.31, 121.21 (2 C’s), 122.71, 127.30, 129.11 (2 C’s),
129.75 (2 C’s), 131.44, 132.21 (2 C’s), 133.37, 135.54,
138.07, 140.63, 141.90, 147.65, 148.37, 150.75, 158.28,
210.03 ppm; ms: m/z (%) 452 [M+] (100), 454 [M + 2]
(28). Anal. Calcd. For C27H21N4OCl (452.95): C, 71.59; H,
4.66; N, 12.36. Found: C, 71.63; H, 4.68; N, 12.39.
2948, 1619, 1477 cm−1; H NMR (300 MHz, CDCl3): δ,
2.94 (t, 2H, J=6.2 Hz, CH2), 3.01 (t, 2H, J=5.6 Hz, CH2),
7.14–7.31 (m, 4H, Ar-H), 7.38–7.53 (m, 5H, Ar-H), 8.26 (s,
1H, Ar-H), 8.35 (d, 2H, J=8.6 Hz, Ar-H), 8.53 (s, 1H, Ar-H).
8.97 (d, J=8.6 Hz, 2H, Ar-H) ppm; ms: m/z (%) 503 [M+]
(100), 505 [M + 2] (96). Anal. Calcd. For C29H19N4Br
(503.41): C, 69.18; H, 3.79; N, 11.12. Found: C, 69.21; H,
3.83; N, 11.16.
1
1
1-(4-Chlorophenyl)-10-Methoxy-3-phenyl-7,8-dihydro-3H-
naphtho[1,2-b]pyrazolo[3,4-h][1,6]- naphthyridine (17c)
Colorless prisms, 0.401 g (82%); mp: 256–257 °C; IR
(KBr): 2994, 2942, 1602, 1567, 1033 cm−1; 1H NMR
(300 MHz, CDCl3): δ, 2.94 (t, 2H, J=5.4 Hz, CH2), 3.04
(t, 2H, J=5.4 Hz, CH2), 3.86 (s, 3H, -OCH3), 6.84 (dd, 1H,
J=8.4 & 2.7 Hz, Ar-H), 7.06 (d, 1H, J=8.4 Hz, Ar-H), 7.18
(d, 1H, J=2.7 Hz, Ar-H), 7.39–7.52 (m, 5H, Ar-H), 8.31
(s, 1H, Ar-H), 8.39 (d, 2H, J=8.2 Hz, Ar-H), 8.56 (s, 1H,
Ar-H), 8.89(d, 2H, J=8.2 Hz, Ar-H) ppm; 13C NMR
(75 MHz, CDCl3): δ, 31.34, 32.28, 57.42, 107.78, 113.43,
114.61, 120.02, 121.33 (2 C’s), 125.36, 127.19, 128.50,
128.94 (2 C’s), 129.62 (2 C’s), 131.29, 132.33 (2 C’s),
133.12, 134.90, 135.46, 138.67, 141.70, 143.12, 147.46,
149.06, 150.17, 158.44, 159.30 ppm; ms: m/z (%) 488 [M+]
(100), 490 [M + 2] (29). Anal. Calcd. For C30H21N4OCl
(488.98): C, 73.68; H, 4.33; N, 11.45. Found: C, 73.71; H,
4.37; N, 11.48.
1-(4-Bromophenyl)-7,7-dimethyl-3-phenyl-7,8-dihydro-3H-
benzo[b]pyrazolo[3,4-h][1,6]- naphthyridine-9(10H)-one
(15 d) Colorless solid, 0.405 g (81%); mp: 248–249 °C;
1
IR (KBr): 3004, 2958, 1704, 1602, 1445 cm−1; H NMR
(300 MHz, CDCl3): δ, 1.14 (s, 6H, (CH3)2), 3.12 (s, 2H,
CH2), 3.74 (s, 2H, CH2), 7.35–7.52 (m, 5H, Ar-H), 8.27 (s,
1H, Ar-H), 8.39 (d, 2H, J=8.6 Hz, Ar-H), 8.54 (s, 1H, Ar-H),
9.01 (d, 2H, J=8.6 Hz,Ar-H) ppm; 13C NMR (75 MHz,
CDCl3): δ, 29.93, 29.93, 39.43, 46.36, 58.44, 109.31, 121.21
(2 C’s), 122.71, 127.30, 129.11 (2 C’s), 129.75 (2 C’s),
131.44, 132.21 (2 C’s), 133.37, 135.54, 138.07, 140.63,
141.90, 147.65, 148.37, 150.75, 158.28, 210.03 ppm; ms: m/z
(%) 497 [M+] (100), 499 [M + 2] (90). Anal. Calcd. For
C27H21N4OBr (497.40): C, 65.19; H, 4.25; N, 11.25. Found:
C, 65.21; H, 4.28; N, 11.28.
1-(4-Bromophenyl)-10-methoxy-3-phenyl-7,8-dihydro-3H-
naphtho[1,2-b]pyrazolo[3,4-h][1,6]- naphthyridine (17d)
White solid, 0.437 g (81%); mp: 263–264 °C; IR (KBr):
General Procedure for the synthesis of compounds 17a–
d A mixture of 1 (0.01 mol) and derivatives of tetralone 16a,
6-methoxy-1-tetralone 16b (0.01 mol) in ethanolic potassium
hydroxide solution (10 cm3, 2%) was refluxed for 25–
30 min. after completion of reaction (TLC check), reaction
mixture was allowed to cool at room temperature. The
separated solid was collected by suction filtration, washed
with ethanol, dried and recrystallized from Ethanol: DMF
(8:2) to furnish compounds 17a–d in 78%–82% yield.
1
2994, 2942, 1602, 1567, 1033 cm−1; H NMR (300 MHz,
CDCl3): δ, 2.94 (t, 2H, J=5.4 Hz, CH2), 3.04 (t, 2H,
J=5.4 Hz, CH2), 3.86 (s, 3H, -OCH3), 6.84 (dd, 1H, J=8.4
& 2.7 Hz, Ar-H), 7.06 (d, 1H, J=8.4 Hz, Ar-H), 7.18
(d, 1H, J=2.7 Hz, Ar-H), 7.39–7.52 (m, 5H, Ar-H), 8.31
(s, 1H, Ar-H), 8.39 (d, 2H, J=8.2 Hz, Ar-H), 8.56 (s, 1H,
Ar-H), 8.89(d, 2H, J=8.2 Hz, Ar-H) ppm; 13C NMR
(75 MHz, CDCl3): δ, 31.34, 32.28, 57.42, 107.78, 113.43,
114.61, 120.02, 121.33(2 C’s), 125.36, 127.19, 128.50,
128.94(2 C’s), 129.62(2 C’s), 131.29, 132.33(2 C’s),
133.12, 134.90, 135.46, 138.67, 141.70, 143.12, 147.46,
149.06, 150.17, 158.44, 159.30 ppm; ms: m/z (%) 533 [M+]
(100), 535 [M + 2] (95). Anal. Calcd. For C30H21N4OBr
(533.43): C, 67.54; H, 3.96; N, 10.49. Found: C, 67.59; H,
3.99; N, 10.53.
1-(4-Chlorophenyl)-3-phenyl-7,8-dihydro-3H-naphtho
[1,2-b]pyrazolo[3,4-h][1,6]naphthyridine (17a) Colorless
prisms, 0.358 g (78%); mp: 264–265 °C; IR (KBr): 3012,
2948, 1619, 1477 cm−1; 1H NMR (300 MHz, CDCl3): δ, 2.94
(t, 2H, J=6.2 Hz, CH2), 3.01 (t, 2H, J=5.6 Hz, CH2), 7.14–
7.31 (m, 4H, Ar-H), 7.38–7.53 (m, 5H, Ar-H), 8.26 (s, 1H,
Ar-H), 8.35 (d, 2H, J=8.6 Hz, Ar-H), 8.53 (s, 1H, Ar-H). 8.97
(d, J=8.6 Hz, 2H, Ar-H) ppm; ms: m/z (%) 458 [M+] (100),
460 [M + 2] (29). Anal. Calcd. For C29H19N4Cl (458.95): C,
75.88; H, 4.16; N, 12.20. Found: C, 75.91; H, 4.18; N, 12.23.
General Procedure for the synthesis of compounds 19a–
d A mixture of 1a–b (0.01 mol) and indanone 18a, 5, 6-
dimethoxy-1-indanone 18b (0.01 mol) in ethanolic potas-
sium hydroxide solution (10 cm3, 2%) was refluxed for 25–
30 min. after completion of reaction (TLC check), reaction
mixture was allowed to cool at room temperature. The
1-(4-Bromophenyl)-3-phenyl-7,8-dihydro-3H-naphtho
[1,2-b]pyrazolo[3,4-h][1,6]naphthyridine (17b) Colorless
prisms, 0.404 g (80%); mp: 268–269 °C; IR (KBr): 3012,

2050
J Fluoresc (2011) 21:2037–2052
separated solid was collected by suction filtration, washed
with cold ethanol, dried and recrystallized from Ethanol:
DMF (8:2) to obtain 19a–d in 81%–85% yield.
(2 C’s), 127.46, 128.90 (2 C’s), 129.75 (2 C’s), 130.51,
131.76 (2 C’s), 132.43, 133.13, 134.82, 135.24, 136.36,
140.70, 143.52, 146.71, 148.09, 149.79, 150.40, 152.44,
159.47 ppm; ms: m/z (%) 549 [M+] (100), 551 [M + 2] (95).
Anal. Calcd. For C30H21N4O2Br (549.43): C, 65.57; H, 3.48;
N, 10.19. Found: C, 65.60; H, 3.51; N, 10.23.
1-(4-Chlorophenyl)-3-phenyl-3,7-dihydroindeno[1,2-b]
pyrazolo[3,4-h][1,6]naphthyridine (19a) Colorless solid,
0.360 g (81%); mp: 233–234 °C; IR (KBr): 3041, 2968,
1
1609, 1410 cm−1; H NMR (300 MHz, CDCl3): δ, 4.08
General Procedure for the synthesis of compounds 21a–
b A mixture of 1a–b (0.01 mol) and cetralene 20
(0.01 mol) in ethanolic potassium hydroxide solution
(10 cm3, 2%) was refluxed for 25–30 min. after completion
of reaction (TLC check), reaction mixture was allowed to
cool at room temperature. The separated solid was collected
by suction filtration, washed with cold ethanol, dried and
recrystallized from Ethanol: DMF (9:1) to obtain com-
pounds 21a–b in 83% yield.
(s, 2H, CH2), 7.31–7.43 (m, 5H, Ar-H), 7.47–7.53 (m, 4H,
Ar-H), 8.35 (s, 1H, Ar-H), 8.42 (d, 2H, J=8.4 Hz, Ar-H), 8.58
(s, 1H, Ar-H), 9.03 (d, 2H, J=8.4 Hz, Ar-H) ppm; ms: m/z
(%) 444 [M+] (100), 446 [M + 2] (29). Anal. Calcd. For
C28H17N4Cl (444.93): C, 75.58; H, 3.84; N, 12.58. Found: C,
75.61; H, 3.87; N, 12.61.
1-(4-Bromophenyl)-3-phenyl-3,7-dihydroindeno[1,2-b]
pyrazolo[3,4-h][1,6]naphthyridine (19b) Colorless solid,
0.410 g (83%); mp: 243–244 °C; IR (KBr): 3041, 2968,
1-(4-Chlorophenyl)-8-(3,4-dichlorophenyl)-3-phenyl-7,
8-dihydro-3H-naphtho[1,2-b]pyrazolo- [3,4-h][1,6]
naphthyridine (21a) Colorless prisms, 0.503 g (83%); mp:
1
1609, 1410 cm−1; H NMR (300 MHz, CDCl3): δ, 4.08
(s, 2H, CH2), 7.31–7.43 (m, 5H, Ar-H), 7.47–7.53 (m, 4H,
Ar-H), 8.35 (s, 1H, Ar-H), 8.42 (d, 2H, J=8.4 Hz, Ar-H), 8.58
(s, 1H, Ar-H), 9.03 (d, 2H, J=8.4 Hz, Ar-H) ppm; ms: m/z
(%) 489 [M+] (100), 491 [M + 2] (97). Anal. Calcd. For
C28H17N4Br (489.38): C, 68.71; H, 3.49; N, 11.44. Found: C,
68.74; H, 3.52; N, 11.47.
1
273–274 °C; IR (KBr): 2995, 2912, 1620, 1412 cm−1; H
NMR (300 MHz, CDCl3): δ, 2.99 (t, 1H, CH), 3.30 (t, 1H,
CH), 3.98 (t, 1H, CH), 7.27–7.34 (m, 4H, Ar-H), 7.37–7.49
(m, 5H, Ar-H), 7.52 (d, 1H, J=3.2 Hz, Ar-H), 7.66 (dd, 1H,
J=3.2 & 8.4 Hz, Ar-H), 8.08 (d, 1H, J=8.4 Hz, Ar-H), 8.38
(s, 1H, Ar-H), 8.44 (d, 2H, J=8.6 Hz, Ar-H), 8.49 (s, 1H,
Ar-H), 8.91(d, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR
(75 MHz, CDCl3): δ, 42.80, 47.45, 107.57, 120.43, 121.49
(2 C’s), 126.37, 126.97, 127.34, 127.89, 128.10, 128.94
(2 C’s), 129.41, 129.91 (2 C’s), 130.04, 130.82, 130.97,
131.40, 132.07 (2 C’s), 132.63, 132.90, 133.84, 134.79,
135.39, 140.70, 141.17, 142.63, 143.52, 146.89, 148.44,
149.88, 159.60 ppm; ms: m/z (%) 602 [M+] (98), 604 [M + 2]
(99), 606 [M + 4] (34), 608 [M + 6] (6). Anal. Calcd. For
C35H21N4Cl3 (603.94): C, 69.60; H, 3.49; N, 9.27. Found: C,
69.64; H, 3.52; N, 9.31.
1-(4-Chlorophenyl)-9,10-dimethoxy-3-phenyl-3,7-
dihydroindeno[1,2-b]pyrazolo[3,4-h][1,6]- naphthyridine
(19c) Colorless prisms, 0.431 g (85%); mp: 251–252 °C;
IR (KBr): 3012, 2984, 1618, 1558, 1029 cm−1; 1H
NMR (300 MHz, CDCl3): δ, 3.89 (s, 3H, -OCH3), 4.04
(s, 3H, -OCH3), 3.94 (s, 2H, CH2), 6.91 (s, 1H, Ar-H), 7.09
(s, 1H, Ar-H), 7.32–7.51 (m, 5H, Ar-H), 8.41 (s, 1H, Ar-H),
8.47 (d, 2H, J=8.4 Hz, Ar-H), 8.56 (s, 1H, Ar-H), 9.01
(d, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR (75 MHz, CDCl3): δ,
38.91, 56.41, 57.34, 107.45, 113.36, 115.67, 120.71, 121.42
(2 C’s), 127.46, 128.90 (2 C’s), 129.75 (2 C’s), 130.51,
131.76 (2 C’s), 132.43, 133.13, 134.82, 135.24, 136.36,
140.70, 143.52, 146.71, 148.09, 149.79, 150.40, 152.44,
159.47 ppm; ms: m/z (%) 504 [M+] (100), 506 [M + 2] (29).
Anal. Calcd. For C30H21N4O2Cl (504.98): C, 71.35; H, 4.18;
N, 11.08. Found: C, 71.37; H, 4.21; N, 11.12.
1-(4-Bromophenyl)-8-(3,4-dichlorophenyl)-3-phenyl-7,
8-dihydro-3H-naphtho[1,2-b]pyrazolo- [3,4-h][1,6]
naphthyridine (21b) Colorless prisms, 0.540 g (83%); mp:
1
278–279 °C; IR (KBr): 2995, 2912, 1620, 1412 cm−1; H
NMR (300 MHz, CDCl3): δ, 2.99 (t, 1H, CH), 3.30 (t, 1H,
CH), 3.98 (t, 1H, CH), 7.27–7.34 (m, 4H, Ar-H), 7.37–7.49
(m, 5H, Ar-H), 7.52 (d, 1H, J=3.2 Hz, Ar-H), 7.66 (dd, 1H,
J=3.2 & 8.4 Hz, Ar-H), 8.08 (d, 1H, J=8.4 Hz, Ar-H), 8.38
(s, 1H, Ar-H), 8.44 (d, 2H, J=8.6 Hz, Ar-H), 8.49 (s, 1H,
Ar-H), 8.91(d, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR
(75 MHz, CDCl3): δ, 42.80, 47.45, 107.57, 120.43, 121.49
(2 C’s), 126.37, 126.97, 127.34, 127.89, 128.10, 128.94
(2 C’s), 129.41, 129.91 (2 C’s), 130.04, 130.82, 130.97,
131.40, 132.07 (2 C’s), 132.63, 132.90, 133.84, 134.79,
135.39, 140.70, 141.17, 142.63, 143.52, 146.89, 148.44,
149.88, 159.60 ppm; ms: m/z (%) 648 [M+] (60), 650 [M + 2]
1-(4-Bromophenyl)-9,10-dimethoxy-3-phenyl-3,7-
dihydroindeno[1,2-b]pyrazolo[3,4-h][1,6]- naphthyridine
(19d) Colorless prisms, 0.464 g (84%); mp: 247–248 °C;
IR (KBr): 3012, 2984, 1618, 1558, 1029 cm−1; 1H
NMR (300 MHz, CDCl3): δ, 3.89 (s, 3H, -OCH3), 4.04
(s, 3H, -OCH3), 3.94 (s, 2H, CH2), 6.91 (s, 1H, Ar-H), 7.09
(s, 1H, Ar-H), 7.32–7.51 (m, 5H, Ar-H), 8.41 (s, 1H, Ar-H),
8.47 (d, 2H, J=8.4 Hz, Ar-H), 8.56 (s, 1H, Ar-H), 9.01
(d, 2H, J=8.4 Hz, Ar-H) ppm; 13C NMR (75 MHz, CDCl3): δ,
38.91, 56.41, 57.34, 107.45, 113.36, 115.67, 120.71, 121.42

J Fluoresc (2011) 21:2037–2052
2051
(98), 652 [M + 4] (54), 654 [M + 6] (12). Anal. Calcd. For
C35H21N4Cl2Br (648.39): C, 68.83; H, 3.25; N, 8.63. Found:
C, 68.86; H, 3.27; N, 8.66.
J=6.3 Hz, CH2), 3.28 (t, 2H, J=6.3 Hz, CH2), 3.97 (s, 2H,
CH2), 7.34–7.53 (m, 5H, Ar-H), 8.34 (s, 1H, Ar-H), 8.45
(d, 2H, J=8.6 Hz, Ar-H), 8.54 (s, 1H, Ar-H), 9.01 (d, 2H,
J=8.6 Hz, Ar-H) ppm; ms: m/z (%) 453 [M+] (100), 455
[M + 2] (29). Anal. Calcd. For C26H20N5OCl (453.94): C,
68.79; H, 4.43; N, 15.42. Found: C, 68.83; H, 4.46; N,
15.45.
General Procedure for the synthesis of compounds 23a–f A
mixture of 1a–b (0.01 mol) and N-substituted piperidones
22a–c (0.01 mol) in ethanolic potassium hydroxide solution
(10 cm3, 2%) was refluxed for 25–30 min. after completion
of reaction (TLC check), reaction mixture was allowed to
cool at room temperature. The separated solid was collected
by suction filtration, washed with cold ethanol, dried and
recrystallized from Ethanol: DMF (9:1) to obtain com-
pounds 23a–f in 81%–84% yield.
1-[1-(4-Bromophenyl)-3-phenyl-3,7,9,10-tetrahydro-
2,3,4,8,11-pentaazcyclopenta[a]- anthracene-8-yl]ethanone
(23d) White solid, 0.418 g (83%); mp: 252–253 °C; IR
(KBr): 3019, 2956, 1715, 1607, 1484 cm−1; 1H NMR
(300 MHz, CDCl3): δ, 2.18 (s, 3H, CH3), 3.14 (t, 2H,
J=6.3 Hz, CH2), 3.28 (t, 2H, J=6.3 Hz, CH2), 3.97(s, 2H,
CH2), 7.34–7.53 (m, 5H, Ar-H), 8.34 (s, 1H, Ar-H), 8.45
(d, 2H, J=8.6 Hz, Ar-H), 8.54 (s, 1H, Ar-H), 9.01 (d, 2H,
J=8.6 Hz, Ar-H) ppm; ms: m/z (%) 498 [M+] (98), 500
[M + 2] (92). Anal. Calcd. For C26H20N5OBr (498.39): C,
62.65; H, 4.03; N, 14.04. Found: C, 62.68; H, 4.06; N, 14.09.
1-(4-Chlorophenyl)-8-methyl-3-phenyl-7,8,9,10-tetrahydro-
3H-2,3,4,8,11-pentaaz-cyclopenta [a]anthracene (23a)
Colorless prisms, 0.348 g (81%); mp: 260–261 °C; IR
(KBr): 3012, 2944, 1627, 1577, 1480 cm−1; 1H NMR
(300 MHz, CDCl3): δ, 2.73 (s, 3H, CH2), 2.89 (t, 2H,
J=5.9 Hz, CH2), 3.04 (t, 2H, J=5.9 Hz, CH2), 3.84 (s, 2H,
CH2), 7.33–7.51 (m, 5H, Ar-H), 8.36 (s, 1H, Ar-H), 8.47
(d, 2H, J=8.4 Hz, Ar-H), 8.53 (s, 1H, Ar-H), 9.03 (d, 2H,
J=8.4 Hz, Ar-H) ppm; 13C NMR (75 MHz, CDCl3): δ,
35.81, 47.09, 56.67, 63.90, 108.31, 119.46, 121.51 (2 C’s),
127.40, 128.69 (2 C’s), 129.23, 129.94 (2 C’s), 131.74,
132.14 (2 C’s), 133.80, 136.32, 141.48, 143.61, 147.86,
149.51, 151.33, 159.08 ppm; ms: m/z (%) 425 [M+] (100),
427 [M + 2] (31). Anal. Calcd. For C25H20N5Cl (425.92):
C, 70.49; H, 4.72; N, 16.43. Found: C, 70.53; H, 4.75; N,
16.45.
1-(4-Chlorophenyl)-3-phenyl-3,7,9,10-tetrahydro-
2,3,4,8,11-pentaaz-cyclopenta-[a]anthracene-8-carboxylic
acid tert-butyl ester (23e) Colorless prisms, 0.433 g (84%);
mp: 230–231 °C; IR (KBr): 2998, 2912, 1738, 1620, 1412,
1
1033 cm−1; H NMR (300 MHz, CDCl3): δ, 1.93 (s, 9H,
CH3), 3.18 (t, 2H, J=5.9 Hz, CH2), 3.28 (t, 2H, J=5.9 Hz,
CH2), 4.11 (s, 2H, CH2), 7.32–7.51 (m, 5H, Ar-H), 8.37
(s, 1H, Ar-H), 8.46 (d, 2H, J=8.6 Hz, Ar-H), 8.51 (s, 1H,
Ar-H), 8.98 (d, 2H, J=8.6 Hz, Ar-H) ppm; ms: m/z (%) 511
[M+] (100), 513 [M + 2] (28). Anal. Calcd. For
C29H26N5O2Cl (512.02): C, 68.02; H, 5.11; N, 13.67.
Found: C, 68.06; H, 5.14; N, 13.70.
1-(4-Bromophenyl)-8-methyl-3-phenyl-7,8,9,10-tetrahydro-
3H-2,3,4,8,11-pentaaz-cyclopenta [a]anthracene (23b)
Colorless prisms, 0.391 g (83%); mp: 257–258 °C; IR
(KBr): 3012, 2944, 1627, 1577, 1480 cm−1; 1H NMR
(300 MHz, CDCl3): δ, 2.73 (s, 3H, CH2), 2.89 (t, 2H,
J=5.9 Hz, CH2), 3.04 (t, 2H, J=5.9 Hz, CH2), 3.84 (s, 2H,
CH2), 7.33–7.51 (m, 5H, Ar-H), 8.36 (s, 1H, Ar-H), 8.47
(d, 2H, J=8.4 Hz, Ar-H), 8.53 (s, 1H, Ar-H), 9.03 (d, 2H,
J=8.4 Hz, Ar-H) ppm; 13C NMR (75 MHz, CDCl3): δ,
35.81, 47.09, 56.67, 63.90, 108.31, 119.46, 121.51 (2 C’s),
127.40, 128.69 (2 C’s), 129.23, 129.94 (2 C’s), 131.74,
132.14 (2 C’s), 133.80, 136.32, 141.48, 143.61, 147.86,
149.51, 151.33, 159.08 ppm; ms: m/z (%) 470 [M+] (100),
472 [M + 2] (96). Anal. Calcd. For C25H20N5Br (470.38):
C, 63.83; H, 4.28; N, 14.87. Found: C, 63.85; H, 4.31; N,
14.90.
1-(4-Bromophenyl)-3-phenyl-3,7,9,10-tetrahydro-2,3,4,8,
11-pentaaz-cyclopenta[a]-anthracene-8-carboxylicacid
tert-butyl ester (23f) Colorless prisms, 0.457 g (82%); mp:
242–243 °C; IR (KBr): 2998, 2912, 1738, 1620, 1412,
1
1033 cm−1; H NMR (300 MHz, CDCl3): δ, 1.93 (s, 9H,
CH3), 3.18 (t, 2H, J=5.9 Hz, CH2), 3.28 (t, 2H, J=5.9 Hz,
CH2), 4.11 (s, 2H, CH2), 7.32–7.51 (m, 5H, Ar-H), 8.37 (s,
1H, Ar-H), 8.46(d, 2H, J=8.6 Hz, Ar-H), 8.51 (s, 1H, Ar-H),
8.98 (d, 2H, J=8.6 Hz, Ar-H) ppm; ms: m/z (%) 556 [M+]
(100), 558 [M + 2] (96). Anal. Calcd. For C29H26N5O2Br
(556.47): C, 62.59; H, 4.70; N, 12.58. Found: C, 62.63; H,
4.74; N, 12.61.
Acknowledgements The author’s sincerely thanks to Department of
Science and Technology (DST)-New Delhi (India) for financial
assistance, Professor D.D.Dhavale, Dept. of Chemistry, University of
Pune for his valuable cooperation for the spectral and analytical data.
We are thankful to management of parent institute and KTHM
College, Nashik.
1-[1-(4-Chlorophenyl)-3-phenyl-3,7,9,10-tetrahydro-
2,3,4,8,11-pentaazcyclopenta[a]- anthracene-8-yl]ethanone
(23c) White solid, 0.373 g (82%); mp: 238–239 °C; IR
(KBr): 3019, 2956, 1715, 1607, 1484 cm−1; 1H NMR
(300 MHz, CDCl3): δ, 2.18 (s, 3H, CH3), 3.14 (t, 2H,

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