Synthesis, photophysical and acidochromic properties of a series of tetrahydrodibenzo[a,i]phenanthridine chromophores

Article abstract of DOI:10.1016/j.dyepig.2016.03.024

A series of luminescent 5-aryl-tetrahydrodibenzo[a,i]phenanthridines was developed through modified synthetic protocol using SnCl₂-acetic acid as a catalyst. The synthesis was consistent with various functionalities and significantly improves t

Full text of DOI:10.1016/j.dyepig.2016.03.024

Accepted Manuscript
Synthesis, Photophysical and Acidochromic Properties of a Series of
Tetrahydrodibenzo[a,i]phenanthridine Chromophores
Umamahesh Balijapalli, Sathiskumar Udayadasan, Easwaramoorthi Shanmugam,
Sathiyanarayanan Kulathu Iyer
PII:
S0143-7208(16)30083-3
10.1016/j.dyepig.2016.03.024
DYPI 5149
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 26 February 2016
Accepted Date: 14 March 2016
Please cite this article as: Balijapalli U, Udayadasan S, Shanmugam E, Iyer SK, Synthesis,
Photophysical and Acidochromic Properties of a Series of Tetrahydrodibenzo[a,i]phenanthridine
Chromophores, Dyes and Pigments (2016), doi: 10.1016/j.dyepig.2016.03.024.
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Synthesis, Photophysical and Acidochromic Properties of a Series of
Tetrahydrodibenzo[a,i]phenanthridine Chromophores
b
Umamahesh Balijapalli a, Sathiskumar Udayadasan b, Easwaramoorthi Shanmugam
Sathiyanarayanan Kulathu Iyer a*
,
a
School of Advanced Sciences, Vellore Institute of Technology University, Vellore, India;
E-Mail: sathiya kuna@hotmail.com; Fax: +91 416 224 3092; Tel: +91 0416 2244520.
b
Chemical Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai – 600 020,
India; E-mail: moorthi@clri.res.in; Fax: +91-44-24411630; Tel: +91-44-24411630.
Graphical abstract
Abstract
A series of luminescent 5-aryl-tetrahydrodibenzo[a,i]phenanthridines was developed through
modified synthetic protocol using SnCl2- acetic acid as a catalyst. The synthesis was consistent
with various functionalities and significantly improves the yields. These derivatives exhibit large
molar absorption coefficients and higher Stokes shift values in the range 9739-2628 cm-1. The
donor and acceptor groups significantly induced the charge transfer character leading to
widespread emission properties in the range of 390-531 nm with moderate quantum yields. The
protonation and quaternization studies of these derivatives revealed the formation of a new red
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shifted absorption band followed by hyperchromic effect in emission, which could be used as an
acidochromic sensor.
1. Introduction
Phenanthridine structure is one of the most important core structures found in a variety of natural
products and biologically important molecules with a wide range of biological activities
including antibacterial, antiprotozoal, antitumor and antiviral activities [1-3]. In addition, the
high charge mobility of this heterocyclic system provides pronounced photoconducting,
optoelectrical switching, and photovoltaic properties [4-6], which are key features in the field of
laser dyes, sensors and electroluminescence [7-9]. The kind of functional groups those can be
tolerated is limited in the Bischler-Napieralski cyclization [10-12] since this method uses P4O10,
POCl3, or PCl5 at elevated temperature, most of the reported methods require multi-step
synthesis, metal catalysts, strict anhydrous conditions and offered poor yields and low diversity
[13-17]. Thus, there is a pressing need for more efficient, versatile and simpler synthetic methods
for the construction of phenanthridine based scaffolds.
Organic light emitting compounds have attracted immense research interest on account of
their potential applications in organic light-emitting diodes (OLEDs), solar cells, laser dyes,
photosensitizers, biomolecular labels, and molecular probes [18-20]. The development of such
luminescent materials, based on highly conjugated species such as polycyclic aromatic
hydrocarbons, has contributed to applications in optoelectronic devices and thin film transistors.
The most prominently known species, including rhodamine, squaraine, cyanine, pyrazoline,
quinoline, imidazopyridine and bodipy derivatives, have been extensively studied [21-27].
Besides, fluorophores incorporating donors and acceptors bound to an extended π-conjugated
chelate have been profoundly studied for various applications ranging from biological sensing
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and imaging to the search for new electroluminescent devices [28-31]. These molecules with
ring-fused structures have attracted notable attention because their flat and rigid-π-conjugated
skeletons bring about a set of desired properties such as intense luminescence, good thermal
stability and high carrier mobility that are important in terms of their applications in high
performance optoelectronics [32-36]. Rigid structures can effectively restrict molecular rotations,
which usually cause serious fluorescence quenching and flat π-conjugated skeletons. This may
facilitate charge transport due to intermolecular π-electron delocalization. Introducing suitable
donor and acceptor groups in this type of π-plane have proved to be an efficient way to tune their
photophysical properties.
In the construction of these light emitting materials, tunable emission color and high
solid-state quantum efficiency are two important issues in terms of optoelectronic applications of
materials. As far as the fluorescence efficiency is concerned, several fluorophores give out a
strong emission when dissolved in solvents and they become weak fluorophores in the solid state
due to either attractive dipole–dipole interactions or intermolecular π-stacking [37-38].
Consequently, these can be used as solid forms in most of the applications. However, the
modality of the quenching process is much more important.
Recent literature demonstrates the continuous investigation for fashionable molecules
with exceptional fluorescence properties, and significant promise has been seen in donor-π-
acceptor conjugated molecules. Herein, we implemented this strategy to obtain a family of
fluorophores based on tetrahydrodibenzo[a,i]phenanthridine moieties [39-41]. Synthesized
derivatives resembled with 2,3,5-triphenylpyridine (2,3,5TPP) and the phenyl groups at 3rd and
5th position of pyridine cyclizes via ethane bridge to 4th and 6thposition and forms 5-aryl-
7,8,13,14-tetrahydrodibenzo[a,i]phenanthridines (THDPs) (Chart 1). Owing to the ethane bridge,
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the phenyl ring rigidity in structures increased. This can effectively restrict molecular rotations
and flat-π-conjugated skeletons may facilitate π-electron delocalization. The photophysical
properties of phenanthridine moieties have recently attracted significant attention [42-43] but the
optical studies of THDPshave not been reported so far. In this report, we describe the synthesis
and optical properties of light emitting THDPs in one-pot reaction of substituted benzaldehydes,
ammonium acetate and 2-tetralone using catalytic amount of SnCl2 in good yields.
2. Results and discussion
2.1 Synthesis and optimization
Initially, the reaction of 6-bromo-2-tetralone (6Br2T) (2 mmol), benzaldehyde (1 mmol) and
ammonium acetate (1 mmol) in ethanol was examined in the presence of catalytic amount of
various Lewis acids ZnCl2, FeCl3,CuCl, CuCl2, Cu(Ac)2, CAN, NiCl2.6H2O, CoCl2.6H2O,
MnCl2.4H2O, LaCl3, SnCl4, and SnCl2.2H2O (Table 1). The formation of the mixture of two
products was observed in most of the cases. Interestingly, we ended up with THDP (5a) up to
40 % yield in 24 h, in the presence of SnCl2.2H2O. For the optimization and identification of the
suitable solvent and effective reaction conditions, 6Br2T, benzaldehyde, ammonium acetate and
10 mol% of catalyst were selected as prototype. Among the chosen solvents, EtOH was
considered the best for the synthesis of phenanthridines. Although acetonitrile, methanol and
isopropanol allowed the reaction to take place at a faster rate, the yield was lesser than the yield
obtained using EtOH as solvent. THF, DCM, dioxane and DMF gave low yields along with side
products, and no desired product was obtained with water and toluene. In order to examine the
role of additives, we performed the same reaction with different additives in ethanol. For this, we
employed 15 mol% catalyst and 1equivalent of additive as a model reaction in ethanol at room
temperature. Interestingly, there was significant change in the reaction time and yield when we
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used acetic acid as an additive in the presence of SnCl2. Then, we thought it would be of interest
to know the catalytic activity of SnCl2 to synthesize substituted phenanthridines by this MCR in
the presence of acetic acid. For this, one equivalent of benzaldehyde was treated with ammonium
acetate in ethanol and warmed in water bath for 5 min to form aldimine in situ. Similarly; two
equivalents of 6Br2T and one equivalent of acetic acid in ethanol were mixed separately and
warmed to form binapthalenone. The aldimine and binapthalenone, thus obtained, were mixed
together in the presence of catalyst and warmed for 5 min. This was kept aside for 24 h after
which it gave a yield up to 74%.
To our knowledge, we identified one report in literature for the synthesis of THDPs with
moderate yields [39]. But in the present protocol, we obtained excellent yields up to 64% with
15mol% of SnCl2 and 1equivalent of acetic acid under the optimized reaction conditions. After
finding the optimal conditions for the three components (1–3) one-pot reaction, we carried out
these reactions with a diverse range of aromatic aldehydes and tetralones to explore the
generality of the reaction, which tuned the photophysical properties as shown in Scheme 1. The
reaction between 2-tetralone (2T) and substituted benzaldehydes gave moderate to good yields in
catalyst-free conditions. When the reaction was carried out with 6Br2T, low yields were
obtained under catalyst-free conditions (5a, 5c and 5h) however moderate to good yields were
obtained under catalytic conditions, and excellent yields were achieved with 2T (4a, 4d and 4h).
In case of 2T, electron donating groups bearing aldehydes gave lower yields compared to
electron withdrawing groups as well as parent in contrast to 6Br2T. Overall, good yields were
obtained in 2T compared to 6Br2T, synthesized derivatives and their yields were given in
Scheme 1. Furthermore, with this effective catalytic system, we synthesized phenanthridine
derivatives irrespective of position of the substituents in aldehyde system. The THDPs structures
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1
were confirmed by the FTIR, H NMR, 13C NMR, HRMS analysis and X-ray crystallography.
The single crystal of 4g was grown in 1:1ethanol and THF solvent mixture, and X-ray
crystallographic structure is given in Fig. 1. Details of the experimental procedures and data for
structural characterization are disclosed in the Supporting Information (SI). In addition, these
compounds were strongly fluorescent in the solution state due to an intramolecular charge
transfer (ICT) process.
Scheme 1. Synthesis of substituted THDPs using SnCl2 as catalyst.
(*) Yields were obtained without SnCl2 was given in brackets for compounds 4a, 4d, 4h, 5a, 5c
and 5f.
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N
N
N
N
F
F
Cl
4a, 89% (85% )*
4c, 88%
4d, 89% (74%)*
4b, 79%
N
N
N
N
O
Br
CN
CF3
4g, 94%
4h, 84% (76%)*
4e, 79%
4f, 89%
Br
Br
O
O
O
N
N
N
N
O
5a, 74% (30%)*
4i, 81%
4k, 83%
4j, 80%
O
Br
Br
Br
Br
Br
Br
Br
Br
N
N
N
N
Br
Br
CF
Br
NO2
CN
Br
5e, 59%
5b, 49%
5c, 59% (15%)*
5d, 58%
Br
Br
Br
Br
Br
O
O
O
O
N
N
N
N
OH
O
5h, 69%
5g, 70%
5f, 77% (21%)*
5i, 66%
O
Br
Br Br
Br
N
N
N
N
5j, 83%
5k, 78%
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2.2 Photophysical studies
Since the optical properties of compounds possessing the THDPs have not been
extensively explored, we decided to study the absorption and emission characteristics of dyes
(Table 2). The photophysical properties of the prepared compounds were thoroughly investigated
by UV/Vis and fluorescence spectroscopy in CHCl3 at room temperature, as shown in Fig. 2. The
UV/Vis spectra showed strong absorption bands at λmax = 262-300 nm, and these were
accompanied in all cases by two to three distinct, broad, structure less maxima at lower energy
with molar absorption coefficients (ε) ranging from 3200 to 100000 L/mol.cm (Table 2). In
general, the lower energy absorption band of 2T derivatives (4a-4k) were blue shifted compared
to 6Br2T derivatives (5a-5k), which could be attributed to the presence of bromine on fused
phenanthridine moiety, slightly inducing the structural perturbations in ground state through
donor-acceptor nature.
The addition of appropriate substituents known to enhance intramolecular charge transfer
(ICT) character, aided THDPs derivatives to emitted strong fluorescence in the blue-green-
yellow region (390−531 nm). Predominantly large Stokes shift values of 9739-2628 cm-1 except
5j and 5k (854 and 151 cm−1) were obtained for the compounds under investigation. As observed
in related structures, this phenomenon indicates large differences (vibrational, electronic,
geometric) between the Franck−Condon state and the excited state. Notably, the solid state
emission maxima of 4a-4k were red shifted when compared to solution with the exception of 4g,
which was blue shifted by 10 nm. On the contrary, the solid state emission maxima of 5a-5k
were blue shifted when compared to that of the solution with the exception of 5a, 5j and 5k,
which were red shifted. The solid state fluorescence spectra of selected compounds are given in
Fig. 3. Fluorescence quantum yields (ΦF) were determined in solution using quinine sulfate as
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reference ΦF = 0.55 in H2SO4 1 N, λex = 366 nm for dyes and it is clear that all the derivatives
exhibit low to moderate quantum yields.
Further, the nature of the functional groups present on the phenanthridine moiety
significantly tuned the optical properties of these derivatives. For example, the emission maxima
of 4h (415 nm) and 4k (421 nm) were slightly red shifted by 8 and 14 nm when compared to that
of 4a (407 nm) shown in Fig. 1a & 2a. In fact, phenanthridines 5j and 5k possessing dialkyl
amino groups displayed bathochromically shifted absorptioncompared to dye 5a. A similar trend
was observed for fluorescence, although the emission maximum of compound 5f and 5i
possessing methoxy and hydroxyl groups were in the same region as 5j and 5k having amine
groups (i.e., 446 nm and 447 nm), dyes 5j and 5k lead to the lowest Stokes shift in this library
(5j: 854 and 5k: 151 cm−1). The corresponding trend was not observed for electron withdrawing
groups of compounds 5d (434 nm) and 5e (419 nm) which possessed cyano and trifluoromethyl
groups and they were in the different emission region to that of nitro 5c (i.e., 531 nm), which
exhibited highest Stokes shift in this library (9739 cm-1) as shown in Fig. 1b & 2b. However, the
effect of halogen groups on the photophysical properties of these derivatives was not significant.
Obviously, increasing the number of methoxy groups in phenanthridines 4h-j had no
considerable impact on their optical properties, indeed the presence of an additional methoxy
groups in 5f-h dyes triggered color change from blue to green region which could be detected by
hand held UV-lamp (λ=365 nm) even though there is no much changes in emission maxima (Fig.
6). This observation helped us to conclude that the incorporation of donor and acceptor groups
lead to increase in ICT character. Based on the above results we have developed 5-substituted-
tetrahydrodibenzo[a,i]phenanthridines based D-π-A chromophore that exhibit sensor applications
and the detailed studies are under progress.
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2.3 Protonation studies
It has been previously demonstrated that 4,6-bis(arylvinyl)pyrimidines, 4-arylvinyl-2,6-di-
(pyridine-2-yl)pyrimidines, quinazolines and diazine derivatives could function as a colorimetric
and luminescent pH sensor due to the basic character of their nitrogen atom/s of the heterocycles
[44-46]. Similarly, the nitrogen atom located on the pyridine ring of phenanthridine had basic
character, and therefore we demonstrated the ability of related phenanthridines to function as a
colorimetric and luminescent pH sensor. The phenanthridines described in this paper showed
significant absorbance and luminescence changes in CHCl3 solutions upon the addition of
trifluoroacetic acid (TFA), and these changes were reversible on neutralization with base
triethylamine (TEA).
The changes observed in the UV−vis spectra of 4a upon addition of TFA are illustrated in
Fig 4. The UV-Vis spectra of compound 4a (60 ꢀM) exhibited an intense absorption band at 267
nm with a shoulder at 317 nm, ascribed to the phenanthridine moiety. An increase in the
concentration of TFA led to the progressive attenuation of the absorption band for the neutral
compound and the appearance of a new, red shifted band corresponded to the protonated species
(see the Supporting Information for spectra of compounds 4g and 4h). In addition, we observed a
decrease and a slight red shifting of the absorption band from 267 nm to 279 nm, and the
appearance of a new band at 335 nm along with the formation of isobestic points at 310 and 322
nm. This bathochromic shift of the absorption band and the formation of the new band could be
attributed to generation of protonated species of compound 4a, which facilitates intramolecular
charge transfer (ICT) from the donor to the phenanthridine moiety.
In Fig. 5, compound 4a (60 ꢀM) exhibits an emission band at 407 nm with a Stokes shift
of 90 nm, when excited at 317 nm. This fluorescence emission was probably due to the lone pair
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of electrons on the nitrogen atom in conjugation with the phenyl group. Upon addition of TFA
(0–100 equiv.), unlike quenching in diazines, a four fold increase with 5 nm red shift of the
fluorescence emission band at 412 nm was observed along with the change in fluorescence
intensity from light to dark blue (inset, Fig. 5). Similar results were obtained when an electron
donor on phenyl ring such as –MeO (4h) was specifically employed (ESI, Fig. S6). Further, the
UV-vis and emission intensity of compound 4g was not significantly affected as a function of the
TFA concentration (ESI, Fig. S6). Thus, from these results we conclude that the acid induced
protonation of compound 4a amplified the phenomenon responsible for the observed
fluorescence hyperchromic effect. The absorbance and emission changes of selected neutral and
protonated species are disclosed in Table 3 (Fig. 6). From Table 3, it is clear that compounds 5j
and 5k show fluorescence quenching upon addition of acid which was assigned to
disorganization of protonated species by second protonation at dialkylamino functionality
consequently disrupting the ICT nature.
2.4 Quaternization studies
Owing to the lone pair of electrons located on nitrogen atom/s of the pyridine ring in
phenanthridine, it exhibits fluorescence in both solid and dissolved solutions. Hence, it was
employed as cell permeant and fluorescing DNA Probes [47]. Quaternization of nitrogen atom or
the use of lone pair of electrons significantly alters the optical properties of these derivatives.
Hence, we demonstrated the utility of lone pair of electrons as a function of quaternization of
nitrogen atom using boron trifluoride. The changes observed in the absorption and emission
spectra of 4a (60 ꢀM) upon addition of boron trifluoride are illustrated in Fig. 7. The increase in
concentration of BF3 showed progressive changes in the absorption band for the neutral
compound followed by the appearance of a new red shifted band attributed to the quaternized
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species. In addition, a decrease and slight red shifting of the absorption band from 267 nm to 283
nm and the formation of a new band at 345 nm was observed along with the formation of
isobestic points at 324 nm. As far as fluorescence response is concerned, upon addition of BF3
(0–10 equiv.), a fivefold increase in the fluorescence emission i.e. hyperchromic band at 416 nm
was observed along with a fluorescence color change from light to dark blue. Further, the
applications of these quaternized species in the field of fluorescence based sensors are studying
in detail in our laboratory.
3. Conclusions
In summary, we have developed SnCl2 catalyzed modified synthetic protocol for the synthesis of
5-aryl-tetrahydrodibenzo[a,i]phenanthridines in moderate to good yields. These derivatives were
highly fluorescent in both solid and solution with large molar absorption coefficients and
exhibited higher Stokes shift values. Further, the donor and acceptor groups present on these
derivatives significantly altered their optical properties and were also necessary to induce the
charge transfer character. An unsubstituted dye 5a emitted deep blue emission at 414 nm.
Considerably, the bathochromically shifted emission of 33 nm for 5j was observed with respect
to dye 5a, where 5j consisted of an electron donating group such as dimethyl amine. This was
more pronounced in the case of 5c, possessing strong electron withdrawing nitro group in which
116 nm red shifted yellow emission was observed. Increasing the methoxy groups in
phenanthridines 4h-j and 5f-h did not have considerable impact on their emission maxima;
however 5f-h showed significant color change from blue to green region which could be
attributed to increasing ICT character. Further, the protonation and quaternization species of
these derivatives showedhyperchromic effect in emission, which can virtually be used in
fluorescence-based sensor applications.
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4. Experimental section
4.1 General information
All organic chemicals and solvents were purchased from Sigma Aldrich, SDFine and they were
used without further purification. 1H and 13C NMR spectra were taken on Bruker 300 MHz using
CDCl3 as the solvent with TMS as an internal standard. Melting points were measured on
Microprocessor based melting point apparatus and were not corrected. HRMS values were
obtained on Joel GC Mate II GC- Mass Spectrometer. FTIR spectra of the synthesized organic
compounds were recorded using a Jasco-4100 spectrometer instrument. UV-Visible spectra were
taken using Hitachi U-2910 spectrophotometer. Fluorescence spectra in solution and solid were
measured using Hitachi F-7000 fluorescence spectrometer. The fluorescence quantum yields
(ΦF) were measured with quinine sulfate (ΦF) 0.55 in 1N H2SO4 solution as a standard, λex =
366nm. Analytical Thin-layer chromatography (TLC) was performed on pre-coated plates
(Merck, silica gel 60 F254). Silica gel (60-120 mesh) was used for column chromatography.
Single crystal X–ray diffraction data were taken on Bruker kappa APEXII. The structures were
solved by direct methods.
4.2 General procedure for the preparation of compound 4a-k.
A mixture of substituted benzaldehydes (2) (10 mmol) and ammonium acetate (3) (11 mmol)
was taken in a 100ml conical flask containing 10ml absolute ethanol at room temperature, sealed
and warmed using water bath for 5min until the dissolution of the solid contents. After bringing
the reaction mixture to room temperature, 15 mol% SnCl2, 1equivalent acetic acid and 2-
tetralone (1) (20 mmol) were added, sealed, and the mixture was warmed for 5 min. The reaction
mixture was then kept aside for 24 h in open air. After the completion of the reaction as
monitored by TLC, the resulting product was purified by column chromatography over silica gel
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(60-120 mesh) using n-hexane and ethyl acetate mixture (9:1) as eluent to give the compounds
(4a-k). The solid thus obtained was further purified by recrystallizing in 1:1 ethanol and
tetrahydrofuran mixture.
5-phenyl-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine (4a):
o
White solid; Melting point: 223-225 C: IR (KBr): 3066, 3034, 2960, 2929, 2831, 2326, 1737,
1
1544, 1487, 1425, 1396, 1290, 1089, 945, 835, 759, 744, 617 cm-1: H NMR (400 MHz,
CDCl3) ppm: 2.79-2.75 (t, J =8.0 Hz, 2H), 2.97-2.93 (t, J =8.0 Hz, 2H), 3.16-3.08 (m, 4H),
6.88-6.87 (d, J =4.0 Hz, 2H), 7.13-7.09 (m, 1H), 7.36-7.24 (m,7H), 7.46-7.43 (dd, J = 16.0, 4.0
Hz, 2H), 7.52-7.50 (d, J = 8.0 Hz, 1H); 13C NMR (100 MHz, CDCl3) ppm: 29.2, 29.5, 29.6, 33.2,
125.6, 126.0, 126.9, 126.9, 127.5, 127.7, 127.8, 127.9, 128.4, 128.7, 128.8, 129.7, 129.8, 133.0,
133.1, 138.7, 139.7, 142.1, 145.7, 154.0, 158.1; HRMS for C27H21N Calculated [M+] m/z
359.1674, Found 359.1660.
5-(2-fluorophenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4b):
Yellow solid; Melting point: 249-251 oC: IR (KBr): 3076, 3020, 2952, 2904, 2881, 2837, 2326,
1739, 1544, 1490, 1454, 1433, 1423, 1394, 1301, 1215, 1155,1080, 945, 806, 744 cm-1: 1H NMR
(400 MHz, CDCl3) ppm: 2.77-2.73 (t, J =8.0 Hz, 2H), 3.28-2.95 (m, 6H), 6.90-6.88 (m, 2H),
6.99-6.95 (t, J =8.0 Hz, 1H), 7.16-7.12 (m, 1H), 7.37-7.22 (m, 6H), 7.55-7.50 (m, 2H); 13C NMR
(100 MHz, CDCl3) ppm: 29.1, 29.4, 29.5, 33.1, 115.9, 116.1, 124.6, 124.7, 125.9, 126.1, 127.0,
127.2, 127.3, 127.8, 127.9, 128.2, 128.8, 129.8, 129.9, 130.1, 130.2, 130.5, 131.7, 131.8, 132.9,
133.2, 138.7, 139.7, 145.2, 148.3, 158.2, 158.4, 160.9; HRMS for C27H20FN Calculated [M+] m/z
377.1580, Found 377.1580.
5-(4-fluorophenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4c):
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Pale yellow solid; Melting point: 216-218 oC: IR (KBr): 3055, 3019, 2945, 2833, 2326, 1745,
1600, 1504, 1454, 1392, 1217, 1091, 999, 950, 839, 744, 617, 484 cm-1: 1H NMR (400 MHz,
CDCl3) ppm: 2.70-2.67 (t, J =6.0 Hz, 2H), 2.89-2.86 (t, J =6.0 Hz, 2H), 3.01-2.98 (t, J =6.0 Hz,
2H), 3.07-3.04 (t, J =6.0 Hz, 2H), 6.83-6.78 (m, 2H), 6.96-6.92 (t, J =8.0 Hz, 2H), 7.07-7.03 (t,
J =8.0 Hz, 1H), 7.27-7.16 (m, 4H), 7.37-7.33 (t, J = 8.0, 1H), 7.43-7.41(d, J =8.0 Hz, 1H); 13C
NMR (100 MHz, CDCl3) ppm:29.2, 29.4, 29.5, 33.2, 115.2, 115.4, 125.7, 126.1, 127.0, 127.1,
127.6, 127.7, 127.9, 128.7, 128.8, 129.5, 131.6, 131.7, 132.8, 132.9, 138.0, 138.1, 138.7, 139.6,
145.8, 152.7, 158.2, 161.4, 163.9; HRMS for C27H20FN Calculated [M+] m/z 377.1580, Found
377.1588.
5-(4-chlorophenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4d):
Yellow solid; Melting point: 239-241 oC: IR (KBr): 3066, 3037, 2960, 2929, 2879, 2831, 2326,
1942, 1911, 1743, 1658, 1537, 1487, 1425, 1394, 1344, 1290, 1089, 1001, 835, 773, 617 cm-1:
1H NMR (400 MHz, CDCl3) ppm: 2.78-2.75 (t, J =6.0 Hz, 2H), 2.97-2.94 (t, J =6.0 Hz, 2H),
3.09-3.06 (t, J =6.0 Hz, 2H), 3.15-3.12 (t, J =6.0 Hz, 2H), 6.90-6.88 (d, J =8.0 Hz, 1H), 6.95-
6.91 (t, J =8.0 Hz, 1H), 7.16-7.12 (t, J =8.0 Hz, 1H), 7.41-7.25 (m, 8H), 7.51-7.49 (d, J = 8.0,
1H); 13C NMR (100 MHz, CDCl3) ppm: 29.2, 29.4, 29.5, 33.2, 125.8, 126.1, 127.0, 127.2, 127.8,
127.8, 127.9, 128.6, 128.7, 128.9, 129.6, 131.31, 132.7, 132.9, 133.8, 138.7, 139.7, 140.5, 145.8,
152.5, 158.3; HRMS for C27H20ClN Calculated [M+] m/z 393.1284, Found 393.1286.
5-(4-bromophenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4e):
Yellow solid; Melting point: 223-225 oC: IR (KBr): 3063, 3027, 2966, 2927, 2879, 2822, 2329,
1922, 1910, 1741, 1638, 1534, 1481, 1415, 1374, 1340, 1291, 1099, 964, 831, 753, 611cm-1: 1H
NMR (400 MHz, CDCl3) ppm: 2.78-2.75 (t, J =6.0 Hz, 2H), 2.96-2.93 (t, J =6.0 Hz, 2H), 3.07-
3.05 (t, J =4.0 Hz, 2H), 3.13-3.09 (t, J =8.0 Hz, 2H), 6.90-6.88 (d, J =8.0 Hz, 1H), 6.95-6.91 (t,
15

ACCEPTED MANUSCRIPT
J =8.0 Hz, 1H), 7.16-7.12 (t, J =8.0 Hz, 1H), 7.35-7.24 (m, 6H), 7.46-7.44 (d, J = 8.0, 2H), 7.51-
7.49 (d, J = 8.0, 1H) ; 13C NMR (100 MHz, CDCl3) ppm: 29.2, 29.4, 29.5, 33.1, 122.1, 125.8,
126.1, 127.0, 127.2, 127.8, 127.8, 127.9, 128.7, 128.9, 129.5, 131.5, 131.6, 132.7, 132.9, 138.7,
139.6, 141.0, 145.9, 152.5, 158.3; HRMS for C27H20BrN Calculated [M+] m/z 437.0779, Found
437.0758.
5-(4-(trifluoromethyl)phenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4f):
Yellow solid; Melting point: 200-202 oC: IR (KBr): 3064, 3033, 2953, 2841, 2326, 1735, 1689,
1614, 1541, 1429, 1396, 1321, 1309, 1168, 1153, 1097, 1018, 950, 835, 765, 671 cm-1: 1H NMR
(400 MHz, CDCl3) ppm: 2.81-2.78 (t, J =6.0 Hz, 2H), 2.98-2.95 (t, J =6.0 Hz, 2H), 3.10-3.07
(t, J =6.0 Hz, 2H), 3.18-3.15 (t, J =6.0 Hz, 2H), 6.84-6.82 (d, J =8.0 Hz, 1H), 6.94-6.90 (t, J
=8.0 Hz, 1H), 7.18-7.14 (t, J =8.0 Hz, 1H), 7.38-7.25 (m, 4H), 7.53-7.51 (d, J = 8.0, 1H), 7.59
(m, 4H); 13C NMR (100 MHz, CDCl3) ppm: 29.1, 29.4, 29.5, 33.1, 125.3, 125.4, 125.6, 125.9,
126.2, 127.1, 127.4, 127.9, 127.9, 128.1, 128.8, 129.2, 129.6, 129.9, 130.3, 132.4, 132.8, 138.8,
139.7, 145.7, 145.9, 152.2, 158.4; HRMS for C28H20F3N Calculated [M+] m/z 427.1548, Found
384.1555.
4-(7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)benzonitrile(4g):
White yellow solid; Melting point: 272-274 oC: IR (KBr): 3053, 3037, 2947, 2897, 2839, 2326,
2222, 1735, 1604, 1541, 1425, 1394, 1290, 1157, 1107, 947, 842, 742, 617, 559 cm-1: 1H NMR
(400 MHz, CDCl3) ppm: 2.80-2.77 (t, J =6.0 Hz, 2H), 2.97-2.94 (t, J =6.0 Hz, 2H), 3.09-3.06
(t, J =6.0 Hz, 2H), 3.17-3.13 (t, J =6.0 Hz, 2H), 6.79-6.77 (d, J =8.0 Hz, 1H), 6.94-6.90 (t, J
=8.0 Hz, 1H), 7.19-7.15 (t, J =8.0 Hz, 1H), 7.38-7.25 (m, 4H), 7.53-7.50 (d, J = 12.0, 1H), 7.57-
7.53 (d, J = 16.0 Hz, 2H), 7.63-7.59 (d, J = 16.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) ppm:
29.1, 29.4, 29.5, 33.1, 111.4, 119.0, 125.9, 126.2, 127.3, 127.6, 128.0, 128.1, 128.4, 128.8, 129.3,
16

ACCEPTED MANUSCRIPT
129.6, 130.7, 132.2, 132.6, 138.8, 139.7, 146.1, 146.7, 151.2, 158.6; HRMS for C28H20N2
Calculated [M+] m/z 384.1626, Found 384.1637.
5-(4-methoxyphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4h):
Pale yellow solid; Melting point: 246-248 oC: IR (KBr): 3049, 3032, 2993, 2900, 2833, 2326,
1745, 1604, 1543, 1508, 1396, 1290, 1230, 1105, 1029, 879, 833, 746, 817, 586 cm-1: 1H NMR
(400 MHz, CDCl3) ppm: 2.77-2.74 (t, J =6.0 Hz, 2H), 2.95-2.92 (t, J =6.0 Hz, 2H), 3.08-3.06
(t, J =4.0 Hz, 2H), 3.13-3.09 (t, J =8.0 Hz, 2H), 3.82 (s, 3H), 6.87-6.85 (d, J =8.0 Hz, 2H),
6.93-6.89 (t, J =8.0 Hz, 1H), 6.97-6.95 (d, J =8.0 Hz, 1H), 7.13-7.09 (t, J =8.0 Hz, 1H), 7.35-
13
7.23 (m, 4H), 7.40-7.38 (d, J = 8.0, 2H), 7.50-7.48 (d, J = 8.0, 1H) ; C NMR (100 MHz,
CDCl3) ppm: 29.3, 29.5, 29.6, 33.2, 55.3, 113.8, 125.7, 126.0, 126.8, 127.1, 127.5, 127.8, 128.6,
128.7, 129.5, 131.1, 133.2, 133.3, 134.5, 138.7, 139.6, 145.7, 153.6, 158.1, 159.4; HRMS for
C28H23NO Calculated [M+] m/z 389.1780, Found 389.1789.
5-(3,4-dimethoxyphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4i):
White solid; Melting point: 188-190 oC: IR (KBr): 3067, 3019, 2962, 2891, 2835, 2326, 1743,
1
1694, 1510, 1452, 1413, 1394, 1271, 1249, 1222, 1138, 1126, 1026, 860, 804, 748 cm-1: H
NMR (400 MHz, CDCl3) ppm: 2.71-2.68 (t, J =6.0 Hz, 2H), 2.89-2.86 (t, J =6.0 Hz, 2H), 3.06-
2.99 (m, 4H), 3.66 (s, 3H), 3.82 (s, 3H), 6.76-6.74 (d, J =8.0 Hz, 1H), 6.90-6.82 (m, 3H), 6.96-
6.94 (d, J =8.0 Hz, 1H), 7.06-7.02 (t, J =8.0 Hz, 1H), 7.28-7.16 (m, 4H), 7.44-7.42 (d, J = 8.0
13
Hz, 1H); C NMR (100 MHz, CDCl3) ppm: 29.2, 29.5, 29.5, 33.2, 55.7, 55.9, 111.1, 113.2,
122.5, 125.6, 126.0, 126.8, 126.9, 127.27, 127.6, 127.8, 128.6, 129.5, 133.1, 133.2, 134.6, 138.6,
139.6, 148.6, 148.9, 153.5, 158.0; HRMS for C28H23NO Calculated [M+] m/z 419.1885, Found
419.1893.
5-(3,4,5-trimethoxyphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4j):
17

ACCEPTED MANUSCRIPT
White solid; Melting point: 218-220 oC: IR (KBr): 3047, 3008, 2939, 2899, 2873, 2829, 2326,
1
2301, 1737, 1579, 1502, 1454, 1392, 1367, 1344, 1263, 1126, 993, 761 cm-1: H NMR (400
MHz, CDCl3) ppm: 2.72-2.68 (t, J =8.0 Hz, 2H), 2.90-2.87 (t, J =6.0 Hz, 2H), 3.09-2.01 (m,
4H), 3.46 (s, 6H), 3.78 (s, 3H), 6.59 (s, 2H), 6.91-6.87 (t, J =8.0 Hz, 2H), 7.07-7.03 (t, J =6.0
Hz. 1H), 7.30-7.16 (m, 4H), 7.44-7.42 (d, J = 8.0 Hz, 1H); 13C NMR (100 MHz, CDCl3) ppm:
29.2, 29.4, 29.5, 33.1, 56.0, 60.9, 107.2, 125.7, 126.1, 126.8, 127.0, 127.5, 127.7, 127.9, 128.7,
128.7, 129.5, 132.8, 133.0, 137.2, 138.0, 138.5, 139.6, 145.8, 153.1, 153.5, 158.0; HRMS for
C28H23NO Calculated [M+] m/z 449.1991, Found 449.1997.
5-(4-isopropylphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(4k):
White solid; Melting point: 176-178 oC: IR (KBr): 3046, 3032, 2958, 2873, 2837, 2326, 1745,
1541, 1427, 1396, 1288, 1228, 1051, 840, 759, 742, 623 cm-1: 1H NMR (400 MHz, CDCl3) ppm:
1.26-1.24 (d, J =8.0 Hz, 6H), 2.78-2.75 (t, J =6.0 Hz, 2H), 2.96-2.88 (m, 3H), 3.10-3.07 (t, J
=6.0 Hz, 2H), 3.15-3.12 (t, J =6.0 Hz, 2H), 3.82 (s, 3H), 6.90-6.86 (t, J =8.0 Hz, 1H), 6.95-6.92
(d, J =8.0 Hz, 1H), 7.13-7.09 (t, J =8.0 Hz, 1H), 7.19-7.17 (d, J = 8.0, 2H), 7.37-7.23 (m, 6H),
7.51-7.49 (d, J = 8.0, 1H) ; 13C NMR (100 MHz, CDCl3) ppm: 24.0, 29.2, 29.5, 29.5, 33.2, 33.9,
125.6, 126.0, 126.4, 126.8, 126.8, 127.2, 127.5, 127.8, 128.7, 129.6, 129.6, 133.1, 133.2, 138.6,
139.5, 139.70, 145.6, 148.5, 154.1, 158.0; HRMS for C30H27N Calculated [M+] m/z 401.2143,
Found 401.2144.
4.3 General procedure for the preparation of compound 5a-k.
These compounds were prepared usingsubstituted benzaldehydes (2) (10mmol), ammonium
acetate (3) (11mmol), 15 mol% SnCl2, 1equivalent of acetic acid and 6-bromo-2-tetralone (1) (20
mmol) according to the similar procedure mentioned in 4a-k.
2,10-dibromo-5-phenyl-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(5a):
18

ACCEPTED MANUSCRIPT
o
Pale yellow solid; Melting point: 242-244 C: IR (KBr): 3116, 3032, 2954, 2871, 2799, 2326,
1737, 1527, 1475, 1435, 1382, 1217, 1074, 821, 761, 696, 655, 617 cm-1: 1H NMR (400 MHz,
CDCl3) ppm: 2.77-2.74 (t, J =6.0 Hz, 2H), 2.94-2.90 (t, J =8.0 Hz, 2H), 3.09-3.05 (t, J =6.0 Hz,
4H), 6.72-6.70 (d, J =8.0 Hz, 1H), 7.01-6.99 (d, J =8.0 Hz, 1H) 7.35-7.33 (m, 4H), 7.45-7.40 (m,
4H), 7.50 (s, 1H) ; 13C NMR (100 MHz, CDCl3) ppm: 28.9, 29.2, 29.2, 32.9, 120.9, 121.6, 126.8,
128.1, 128.3, 128.4, 128.6, 128.8, 129.2, 129.6, 129.8, 130.0, 130.9, 131.0, 131.6, 131.6, 131.8,
131.9, 140.7, 141.5, 141.8, 145.2, 154.2, 158.0;HRMS for C27H19Br2N Calculated [M+] m/z
514.9884, Found 514.9880.
2,10-dibromo-5-(4-bromophenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(5b):
Brown solid; Melting point: 295-297 oC: IR (KBr): 3089, 3006, 2956, 2899, 2841, 2326, 1734,
1
1726, 1678, 1587, 1475, 1381, 1274, 1186, 1093, 919, 792, 611 cm-1: H NMR (400 MHz,
CDCl3) ppm: 2.80-2.77 (t, J =6.0 Hz, 2H), 2.98-2.91 (m, 2H), 3.12-3.07 (m,4H), 6.78-6.76 (d, J
=8.0 Hz, 1H), 7.11-7.09 (d, J =8.0 Hz, 1H), 7.38-7.34 (t, J =8.0 Hz, 3H), 7.53-7.43 (m , 5H); 13C
NMR (100 MHz, CDCl3) ppm: 28.9, 29.1, 29.1, 32.7, 121.3, 121.8, 122.6, 127.1, 128.2, 129.0,
129.3, 130.0, 130.0, 130.9, 130.9, 131.4, 131.6, 131.7, 140.7, 141.7, 145.6, 152.6, 158.1; HRMS
for C27H19Br2N Calculated [M+] m/z 596.1505, Found 596.1505.
2,10-dibromo-5-(4-nitrophenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(5c):
Yellow solid; Melting point: 262-264 oC: IR (KBr): 3117, 3030, 2954, 2839, 2345, 1726, 1589,
1512, 1475, 1377, 1342, 1282, 1083, 817, 674, 630, 616 cm-1: 1H NMR (400 MHz, CDCl3) ppm:
2.80-2.77 (t, J =6.0 Hz, 2H), 2.95-2.90 (m, 2H), 3.12-3.02 (m,4H), 6.14-6.12 (d, J =8.0 Hz, 1H),
6.65-6.63 (d, J = 8.0 Hz, 1H), 6.91-6.89 (d, J =8.0 Hz, 1H), 7.52-7.31 (m,5H), 7.63-7.61 (d, J =
8.0 Hz, 1H), 8.22-8.20 (d, J = 8.0 Hz, 2H) ; 13C NMR (100 MHz, CDCl3) ppm:28.7, 28.9, 29.0,
29.1, 32.6, 32.8, 121.4, 121.8, 122.1, 123.8, 124.5, 126.2, 127.8, 128.8, 129.2, 129.3, 130.1,
19

ACCEPTED MANUSCRIPT
130.7, 130.8, 130.8, 131.8, 140.6, 140.8, 141.6 ,141.8, 145.6, 146.2, 147.4, 147.5, 148.0, 151.4,
158.5, 158.8; HRMS for C27H19Br2N Calculated [M+] m/z 559.9735, Found 559.9744.
4-(2,10-dibromo-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)benzonitrile(5d):
White solid; Melting point: >300 oC: IR (KBr): 3111, 3018, 2954, 2841, 2326, 2171, 1741, 1531,
1
1475, 1381, 1274, 1228, 1186, 1093, 999, 825, 794, 613, 569 cm-1: H NMR (400 MHz,
CDCl3) ppm: 2.79-2.76 (t, J =6.0 Hz, 2H), 2.95-2.92 (t, J =6.0 Hz, 2H), 3.11-3.04 (m,4H), 6.65-
6.63 (d, J =8.0 Hz, 1H), 7.07-7.04 (dd, J =16.8, 4.0 Hz, 1H), 7.36-7.34 (d, J =8.0 Hz, 1H), 7.47-
7.45 (d, J =8.0 Hz, 2H), 7.52 (s, 1H), 7.57-7.55 (d, J =8.0 Hz, 2H), 7.66-7.64 (d, J =8.0 Hz,
2H); 13C NMR (100 MHz, CDCl3) ppm: 28.7, 29.0, 29.1, 32.8, 111.7, 118.8, 121.7, 122.0, 127.6,
128.5, 129.1, 129.3, 130.0, 130.3, 130.6, 130.9, 131.0, 131.0, 131.4, 132.3, 140.8, 141.8, 145.5,
146.1, 151.7, 158.4; HRMS for C27H19Br2N Calculated [M+] m/z 539.9837, Found 539.9833.
2,10-dibromo-5-(4-(trifluoromethyl)phenyl)-7,8,13,14-
tetrahydrodibenzo[a,i]phenanthridine(5e):
Yellow solid; Melting point: 296-298 oC: IR (KBr): 3102, 3015, 2954, 2895, 2835, 1763, 1529,
1477, 1381, 1315, 1290, 1170, 1118, 1107, 1093, 1060, 877, 817, 798, 626 cm-1: 1H NMR (400
MHz, CDCl3) ppm: 2.79-2.76 (t, J =6.0 Hz, 2H), 2.95-2.91 (t, J =8.0 Hz, 2H), 3.11-3.04 (m,4H),
6.68-6.66 (d, J =8.0 Hz, 1H), 7.06-7.04 (d, J =8.0 Hz, 1H), 7.36-7.34 (d, J =8.0 Hz, 3H), 7.36-
7.34 (d, J =8.0 Hz, 1H), 7.47-7.44 (d, J =8.0 Hz, 2H), 7.52 (s, 1H), 7.57-7.55 (d, J =8.0 Hz, 2H),
7.63-7.61 (d, J =8.0 Hz, 2H) ; 13C NMR (100 MHz, CDCl3) ppm: 28.8, 29.1, 29.2, 30.9, 32.8,
121.4, 121.9, 122.8, 125.5, 125.5, 127.4, 128.4, 129.0, 129.3, 129.9, 130.0, 130.1, 130.2, 130.9,
130.9, 131.2, 131.5, 140.7, 141.8, 145.1, 145.4, 152.4, 158.3; HRMS for C27H19Br2N Calculated
[M+] m/z 582.9758, Found 582.9760.
2,10-dibromo-5-(4-methoxyphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridine(5f):
20

ACCEPTED MANUSCRIPT
White solid; Melting point: 264-266 oC: IR (KBr): 3110, 3024, 2959, 2866, 1815, 1661, 1606,
1
1504, 1449, 1375, 1320, 1245, 1187, 1071, 978, 926, 748, 643 cm-1: H NMR (400 MHz,
CDCl3) ppm: 2.76-2.73 (t, J =6.0 Hz, 2H), 2.93-2.90 (t, J =6.0 Hz, 2H), 3.07-3.04 (t, J =6.0
Hz,4H), 6.81-6.79 (d, J =8.0 Hz, 1H), 6.89-6.87 (d, J = 8.0 Hz, 2H), 7.05-7.03 (d, J =8.0 Hz,
1H), 7.44-7.32 (m,4H), 7.49 (s, 1H) ; 13C NMR (100 MHz, CDCl3) ppm: 28.9, 29.2, 29.2, 32.9,
55.3, 114.0, 120.8, 121.4, 126.4, 127.8, 128.9, 129.1, 129.8, 129.9, 130.8, 130.9, 131.0, 131.9,
132.1, 133.9, 140.6, 141.7, 145.2, 153.9, 158.0, 159.6; HRMS for C27H19Br2N Calculated [M+]
m/z 544.9990, Found 544.9990.
2,10-dibromo-5-(3,4-dimethoxyphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]
phenanthridine(5g):
White solid; Melting point: 232-234 oC: IR (KBr): 3104, 3057, 3010, 2971, 2831, 1799, 1589,
1512, 1462, 1417, 1382, 1332, 1251, 1172, 1028, 796 cm-1: 1H NMR (400 MHz, CDCl3) ppm:
2.79-2.76 (t, J =6.0 Hz, 2H), 2.96-2.93 (t, J =6.0 Hz, 2H), 3.11-3.07 (m,4H), 3.81 (s, 3H), 3.93
(s, 3H), 6.86-6.81 (m, 2H), 6.99-6.97 (d, J =8.0 Hz, 1H), 7.01 (s, 1H) 7.08-7.06 (d, J =8.0 Hz,
1H), 7.37-7.35 (d , J =8.0 Hz, 1H), 7.42 (s, 1H), 7.47-7.45 (d , J =8.0 Hz, 1H), 7.53 (s, 1H) ; 13C
NMR (100 MHz, CDCl3) ppm: 25.6, 28.9, 29.2, 32.7, 55.8, 55.9, 67.9, 111.1, 112.9, 120.8,
121.6, 122.5, 126.6, 128.0, 128.9, 129.2, 129.8, 129.9, 130.8, 130.9, 131.8, 132.0, 133.7, 140.5,
141.7, 145.4, 148.9, 149.2, 153.7, 157.9; HRMS for C27H19Br2N Calculated [M+] m/z 575.0096,
Found 575.0090.
2,10-dibromo-5-(3,4,5-trimethoxyphenyl)-7,8,13,14-tetrahydrodibenzo[a,i]
phenanthridine(5h):
White solid; Melting point: 271-273 oC: IR (KBr): 3101, 3019, 2941, 2897, 2831, 2335, 1737,
1583, 1506, 1463, 1423, 1390, 1236, 1124, 1103, 1001, 813, 696, 575 cm-1: 1H NMR (400 MHz,
21

ACCEPTED MANUSCRIPT
CDCl3) ppm: 2.77-2.74 (t, J =6.0 Hz, 2H), 2.94-2.91 (t, J =6.0 Hz, 2H), 3.09-3.06 (t, J =6.0 Hz,
4H), 3.74 (s, 6H), 3.89 (s, 3H), 6.63 (s, 2H), 6.82-6.80 (d, J =8.0 Hz, 1H), 7.09-7.07 (d, J =8.0
Hz, 1H) 7.35-7.33 (d, J =8.0 Hz, 1H), 7.40 (s, 1H), 7.46-7.44 (d , J =8.0 Hz, 1H), 7.51 (s, 1H) ;
13C NMR (100 MHz, CDCl3) ppm: 28.8, 29.2, 32.8, 56.1, 60.9, 107.1, 120.9, 121.6, 126.9,
128.0, 128.9, 129.2, 129.8, 130.0, 130.9, 130.9, 131.7, 131.7, 136.7, 138.3, 140.5, 141.7, 145.2,
153.3, 153.8, 157.9; HRMS for C27H19Br2N Calculated [M+] m/z 605.0201, Found 605.0206.
4-(2,10-dibromo-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)phenol(5i):
White solid; Melting point: >300 oC: IR (KBr): 3333, 3097, 3002, 2949, 2337, 1737, 1724, 1608,
1587, 1514, 1479, 1392, 1274, 1215, 1002, 889, 867, 821, 798, 742, 615 cm-1: 1H NMR (400
MHz, CDCl3) ppm: 2.76-2.73 (t, J =6.0 Hz, 2H), 2.91 (m, 4H), 3.05-3.02 (t, J =6.0 Hz, 2H),
6.75-6.72 (d, J =8.0 Hz, 2H), 6.79-6.77 (d, J = 8.0 Hz, 1H), 7.15-7.13 (d, J =8.0 Hz, 1H), 7.19-
13
7.17 (d, J =8.0 Hz,2H), 7.56-7.50 (m,3H), 7.65 (s,1H), 9.63 (s, 1H) ; C NMR (100 MHz,
CDCl3) ppm: 28.2, 28.2, 32.2, 115.0, 119.9, 120.7, 125.4, 127.0, 128.2, 128.9, 129.7, 130.4,
130.4, 130.5, 130.9, 131.6, 131.9, 132.2, 141.3, 141.7, 145.4, 153.5, 157.3, 157.4; HRMS for
C27H19Br2N Calculated [M+] m/z 530.9833, Found 530.9830.
4-(2,10-dibromo-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)-N,N-
dimethylaniline(5j):
o
Pale green solid; Melting point: 243-245 C: IR (KBr): 3114, 3022, 2970, 2831, 2326, 1737,
1606, 1514, 1475, 1427, 1384, 1371, 1338, 1313, 1255, 1186, 1089, 1068, 889, 817, 617 cm-1:
1H NMR (400 MHz, CDCl3) ppm: 2.75-2.72 (t, J =6.0 Hz, 2H), 2.91-2.88 (t, J =6.0 Hz, 2H),
2.98 (s, 6H), 3.05-3.02 (m,4H), 6.68-6.66 (d, J =8.0 Hz, 2H), 6.93-6.91 (d, J = 8.0 Hz, 1H),
7.06-7.04 (d, J =8.0 Hz, 1H), 7.33-7.29 (t, J =8.0 Hz, 3H), 7.43-7.39 (t, J =8.0 Hz, 2H), 7.48 (s,
1H) ; 13C NMR (100 MHz, CDCl3) ppm: 29.0, 29.3, 32.9, 40.4, 112.2, 120.5, 121.2, 125.8,
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127.5, 128.8, 129.1, 129.1, 129.7, 129.9, 130.7, 130.7, 130.9, 132.1, 132.6, 140.5, 141.7, 145.1,
150.4, 154.50, 157.96; HRMS for C27H19Br2N Calculated [M+] m/z 586.0619, Found 586.0615.
4-(2,10-dibromo-7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)-N,N-
diethylaniline(5k):
Pale green solid; Melting point: >300 oC: IR (KBr): 3100, 3010, 2970, 2950, 2818, 2330, 1880,
1726, 1606, 1519, 1473, 1421, 1386, 1359, 1224, 1197, 1159, 1097, 997, 871, 813, 615, 578 cm-
1: 1H NMR (400 MHz, CDCl3) ppm: 1.18-1.15 (t, J =6.0 Hz, 3H), 2.75-2.72 (t, J =6.0 Hz, 2H),
2.91-2.88 (t, J =6.0 Hz, 2H), 3.06-3.01 (m,4H), 3.40-3.34 (q, J =6.0 Hz, 2H), 6.62-6.60 (d, J
=8.0 Hz, 2H), 7.01-6.99 (d, J = 8.0 Hz, 1H), 7.07-7.05 (d, J =8.0 Hz, 1H), 7.43-7.25 (m, 5H),
7.48 (s, 1H); 13C NMR (100 MHz, CDCl3) ppm: 12.6, 29.0, 29.3, 29.3, 33.0, 44.4, 111.6, 120.4,
121.1, 125.5, 127.3, 128.1, 128.8, 129.0, 129.6, 129.9, 130.7, 130.9, 130.9, 132.2, 132.8, 140.5,
141.7, 145.0, 147.7, 154.6, 157.9; HRMS for C27H19Br2N Calculated [M+] m/z 558.0306, Found
558.0309.
Supporting Information
1H and 13C NMR spectra for all compounds and Optical data were included. This material is
available free of charge via the Internet at
Acknowledgements
B.U thanks CSIR for providing Senior Research Fellowship (CSIR-SRF). S. E and U. S thank
DST (Grant No.SERB/F/4232/2013-15) India. The work is also supported by CSIR
suprainstitutional, XIIth five year plan project STRAIT. We also thank VIT-SIF for NMR
facilities respectively. The authors thank Dr. R. Srinivasan, SSL-VIT for language editing.
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