Synthesis and photophysical studies on triazole bridged dendrimers with phenothiazine as surface unit

Article abstract of DOI:10.3998/ark.5550190.p008.375

Synthesis and photophysical properties of some novel 1, 2, 3-triazole bridged phenothiazine dendrimers with enone and S-(-)-BINOL core is described. ARKAT-USA, Inc.

Full text of DOI:10.3998/ark.5550190.p008.375

General Papers
ARKIVOC 2014 (iv) 67-79
Synthesis and photophysical studies on triazole bridged dendrimers
with phenothiazine as surface unit
Perumal Rajakumar,* Chinnadurai Satheeshkumar, and Mahalingam Ravivarma
Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 25, India
E-mail: perumalrajakumar@gmail.com
DOI: http://dx.doi.org/10.3998/ark.5550190.p008.375
Abstract
Synthesis and photophysical properties of some novel 1, 2, 3-triazole bridged phenothiazine
dendrimers with enone and S-(-)-BINOL core is described.
Keywords: Dendrimer, phenothiazine, 1, 2, 3-triazole, click chemistry
Introduction
Dendrimers1 are very unique type of macromolecule with hyperbranched and perfectly defined
structure that have attracted much interest and an innovative area of research in supramolecular
chemistry. Due to the special structure and unusual properties, dendrimers are utilized for a wide
range of biomedical and material applications, such as antibacterial,2 drug delivery,3 light-
harvesting ability,4 nonlinear optical (NLO),5 organic light-emitting diodes (OLEDs)6 and so on.
Moreover, dendrimers with rigid structures can possibly be regularly assembled by packing on a
plate without deformation of the molecule and are expected to expand the field of
nanomaterials.7
Click chemistry coined by Sharpless,8 refers to a Cu(I) catalyzed Huisgen 1,3-dipolar
cycloaddition of azides to alkynes, providing 1,4-disubtituted 1,2,3-triazole. The advantages of
employing click chemistry are the excellent regioselectivity, tolerance of sensitive functional
group, atom-economy, no protection-deprotection protocol, mild reaction conditions and
excellent yields. Triazoles have interesting chemical properties, which include high aromatic
stabilization and tolerance to acidic and basic as well as oxidative and reductive conditions.
Moreover, 1,2,3-triazole derivatives are important materials in pharmaceuticals such as anti-
HIV,9 antiviral,10 and antimicrobial.11 In addition, triazole derivatives play a pivotal role in the
field of supramolecular assemblies.12 Furthermore, synthesis of dendrimers using click chemistry
has received much attention during recent times due to their interesting biological applications.13
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S
S
N
N
N
N
N
N
N
N
(CH2)6
N
(CH2)6
O
N
N
N
O
N
N
O
O
O
O
N
N
O
O
N
N
N
N
O
O
N
N
N
N
N
N
N
N
N
N
N
N
(CH2)6
(H2C)6
(CH2)6
(CH2)6
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
S
S
S
S
1
2
S
S
N
N
N
N
N
N
N
N
(CH2
N
)
(CH2)
6
6
O
N
N
N
O
N
N
O
O
n
O
O
n
N
N
O
O
N
N
N
N
O
O
N
N
N
N
N
N
N
N
N
N
N
N
(CH2)
(H2C)6
6
(CH2
)
(CH2)
6
N
6
N
N
N
N
N
N
N
N
N
N
N
N
N
S
N
N
S
S
S
5 (n= 1)
6 (n = 2)
3 (n= 1)
4 (n = 2)
S
S
N
N
N
N
N
N
N
N
(CH2)6
N
(CH2)6
N
N
N
N
N
O
O
O
O
N
N
N
N
N
N
O
O
O
O
N
N
N
N
N
N
N
N
N
N
N
N
(H2C)6
(CH2)
6
(CH2)6
(CH2)6
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
S
S
S
S
8
7
Figure 1. Molecular structure of phenothiazine dendrimers 1-8.
Recently, we have reported the synthesis of dendrimer with dimethyl isophthalate,14
pyrrolidine,15 quinoline,16 and pyreno-chalcone17 as surface groups with 1,2,3-triazole as
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bridging unit. Phenothiazine belongs to an important class of tricyclic nitrogen-sulphur
heterocyclic compound. phenothiazine-based dendrimers exhibit remarkable optical and
electrochemical properties.18 Further, the phenothiazine heterocyclic system shows antimicrobial,
anticancer, antiviral, anticonvulsant and antimalarial activity.19 The dendrimers with S-(-)-
BINOL core could exhibit chiroptical, photophysical properties,20 and also used as
enantioselective Lewis acid catalysts.21 In connection with this, the present investigation deals
with the synthesis and photophysical properties of some novel triazole bridged dendrimers 1-8
(Figure 1) bearing phenothiazine as surface group by convergent methodology.
Results and Discussion
The bifunctional 1-azido-6-bromohexane 10 was synthesized by the reaction of 1,6-
o
dibromohexane with one equivalent of NaN3 in a mixture of acetone and water (9:1) at 60 C.
Further, reaction of N-propargyl phenothiazine22 9 with the azide 10 under click reaction
conditions of CuSO4.5H2O (5 mol %) and sodium ascorbate (10 mol %) in a mixture of THF and
water (1:1) at room temperature for 10 h gave the bromo compound 11 in 90% yield. The
bromide 11 was converted to the azide 12 in 91% yield using NaN3. Reaction of 3,5-
bis(propargyloxy)benzyl chloride16 13 with 2.1 equiv. of azide dendron 12 under click chemistry
conditions afforded the first generation dendritic chloride (G1-Cl) 14 in 89% yield. The dendritic
o
chloride 14 with NaN3 in DMF at 60 C afforded the first generation dendritic azide (G1-N3) 15
in 87% yield (see Scheme 1).
Scheme 1. Reagents and conditions: (i) Br-(CH2)6-N3, (10) (1 equiv.), CuSO4.5H2O (5 mol %),
sodium ascorbate (10 mol %), THF: H2O (1:1, v/v), rt, 10 h, 11 (90%) and 14 (89%). (ii) NaN3,
DMF, 10 h, 60 oC, 12 (91%) and 15 (87%).
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The 1H NMR spectrum of compound 15 displayed the ten methylene protons adjacent to the
nitrogen atom of triazole ring and azide functionality at δ 4.11-4.2, and the rest of the methylene
protons of the hexyl unit appear as two set of multiplets eight proton each at δ 1.11-1.18 and
1.56-1.85 and singlets at δ 5.08 and 5.10 for N–CH2- adjacent to phenothiazine and O-CH2-
protons respectively in addition to the other aliphatic and aromatic proton signals. The 13C NMR
spectrum of dendritic azide 15 showed N–CH2- and O-CH2- carbon signals at δ 54.5 and 61.9 in
addition to the aliphatic and aromatic carbon signals. The ESI mass spectrum of 15 showed
molecular ion peak m/z 1052 (M+H)+. The molecular formula of 15 was further confirmed from
analytical data.
The core units bis(propargyloxy)dienone 19, bis(propargyloxy)pentanone 20,
bis(propargyloxy)hexanone23 21 and bis(propargyloxy)S-(-) BINOL 22 were obtained in 63%,
82%, 76% and 78% yields respectively by the O-alkylation of 16, 17, 18 and S-(-) BINOL with
2.1 equiv. of propargyl bromide in the presence of K2CO3 in DMF (Scheme 2).
Scheme 2. Reagents and conditions: (i) Propargyl bromide (2.1 equiv.), K2CO3, DMF, 60 oC, 24
h, 19 (63%), 20 (82%), 21 (76%) and 22 (78%).
The synthetic pathway leading to the enone and S-(-)-BINOL based zeroth generation
dendrimers with phenothiazine surface group is shown in Scheme 3. Reaction of bis-
propargyloxy core unit 19-21 and 22 with phenothiazine dendritic azide 12 under click reaction
conditions afforded 1, 2, 3-triazole bridged phenothiazine dendrimers 1, 3, 4 and 7 in good yields
(see Scheme 3). The 1H NMR spectrum of dendrimer 4 displayed singlets at δ 5.20 and 5.25 for
the N-methylene and O-methylene protons, in addition to the signals for aliphatic and aromatic
protons. The 13C NMR spectrum of dendrimer 4 displayed N-methylene and O- methylene
carbons at δ 49.8 and 61.8 respectively, the carbonyl carbon appeared at δ 189.7, in addition to
the signals for aliphatic and aromatic carbons. The appearance of molecular ion peak at m/z
1215.6 (M+Na)+ in mass spectrum of the dendrimer 4 also confirmed the structure. Similarly, the
structure of the dendrimers 1, 3 and 7 was confirmed from spectral and analytical data.
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Scheme 3. Reagents and conditions: (i) CuSO4.5H2O (5 mol %), sodium ascorbate (10 mol %),
THF: H2O (1:1, v/v), rt, 10 h, 1 (86%), 3 (84%), 4 (85%) and 7 (92%).
N3
5, 6
2
O
O
i
N
N
N
N
N
N
19
20, 21
(0.5 equiv.)
(0.5 equiv.)
N
N
N
N
N
N
N
N
S
S
15
22
(0.5 equiv.)
8
Scheme 4. Reagents and conditions: (i) CuSO4.5H2O (5 mol %), sodium ascorbate (10 mol %),
THF: H2O (1:1, v/v), rt, 10 h, 2 (84%), 5 (80%), 6 (86%) and 8 (83%).
Similar technique was adopted to synthesize the first generation dendrimers. Reaction of the
bis-propargyloxy core moieties 19-22 with 2.0 equiv. of dendritic azide (G1-N3) 15 in the
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presence of the Cu(I)-catalyzed Huisgen click reaction conditions generated the first generation
dendrimers (G1) 2, 5, 6 and 8 in 84%, 80%, 86% and 83% yields, respectively (see Scheme 4).
1
In the H NMR spectrum, the chiral phenothiazine dendrimer 8 showed singlets at δ 5.07 for N-
methylene and at δ 5.17 for O-methylene protons, in addition to the signals for aliphatic and
aromatic protons. The 13C NMR spectrum of dendrimer 8 displayed N-methylene and O-
methylene carbons at δ 50.0, 53.7, 61.9 and 63.9 in addition to the signals for aliphatic and
aromatic carbons. In the MALDI-TOF mass spectrum of 8, the molecular ion peak appeared at
m/z 2466 (M)+ and the structure of the dendrimer 8 was further confirmed from analytical data.
Similarly, the structure of the dendrimers 2, 5 and 6 was confirmed from spectral and analytical
data.
Photophysical studies
The photophysical property of phenothiazine dendrimers 1-8 is listed in Table 1. Figure 2a show
the absorption spectra of dendrimers 1-8 in DMF.. There is a broad absorption band at 284-386
nm due to the presence of triazole and phenothiazine units. In fact this observation suggests that
both the chromophores viz triazole and phenothiazine could be responsible for the broad
absorption bands for the dendrimers 1-8. Molar extinction coefficients of the absorption bands at
a given concentration varies as the generation of the dendrimer increases. The absorbance in the
UV spectrum is probably controlled by the number of phenothiazine and triazole units.
Table 1. Photophysical data for dendrimers 1-8 in DMF (1×10-5 mol/L)
Dendrimers
λ
abs max
(nm)
359
ε x 10-5
M−1 cm−1
1.55
0.96, 0.91
0.56
0.92
λem max
(nm)
445
440, 520
433, 462
438
ФF
0.0017
0.0036
0.0050
0.0032
0.0143
0.0070
0.0778
0.1148
1
2
3
4
5
6
7
8
321, 358
386
358
385
0.65
439
431
433
437
321, 357
297, 324
312
0.52, 0.61
0.26, 0.21
0.34
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Figure 2. (a) Absorption spectra of dendrimers 1-8 in DMF (1×10-5 mol/L). (b) Fluorescence
spectra of dendrimers 1-8 in DMF (1×10-5 mol/L).
Figures 2b shows the fluorescence spectra of dendrimers 1-8 in DMF and the fluorescence
parameters for all the dendrimers are presented in Table 1. As shown in Figure 3, on excitation at
360 nm, the dendrimers 1-8 give emission band in range at 431-520 nm due to the triazole and
phenothiazine moieties. The fluorescence intensity of the dendrimers increases as the generation
increases, which are consistent with the increased number of both fluorophoric triazole and
phenothiazine units, otherwise known as multivalency effect in dendrimer chemistry. The
fluorescence quantum yields Фf of dendrimers 1-8 have been measured in DMF using quinine
sulphate in 0.1N H2SO4 as the standard. The quantum yields of dendrimers 1-8 are listed in Table
1. Thus as the generation of the dendrimer increases, the quantum yield also increases.
Conclusions
In conclusion, we have synthesized various dendritic architectures with phenothiazine surface
group and 1, 2, 3-triazole as bridging unit through click reaction by convergent approach in good
yields. The dendrimers reported herein possesses biologically active enone core and
phenothiazine surface group. Synthesis of other such phenothiazine dendrimers and their
biological activity are under way.
Experimental Section
General. All the melting points reported were uncorrected and are determined using Toshniwal
1
melting point apparatus by open capillary tube method. The H and 13C NMR spectra were
recorded on Bruker 300 MHz spectrometer. The chemical shifts are reported in ppm (δ) with
TMS as an internal standard and coupling constant (J) are expressed in Hz. MALDI-TOF mass
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spectra on Voyager-DE PRO mass spectrometer using a α-cyano-4-hydroxy cinnamic acid
(CHCA) matrix and ESI-PerkinElmer Sciex, API 3000 mass spectrometer. The QTOF-MS
spectra were recorded on Xevo G2-S QT mass spectrometer.
Elemental analyses were
performed on a Perkin-Elmer 240B elemental analyzer. TLC was performed either on glass
plates coated with silica gel-G (ACME) of about 0.25 mm thickness and visualized with iodine
or on pre-coated plastic sheets (POLYGRAM SIL G/U254) and detected under UV light.
Column chromatography was carried out with silica gel (ACME, 60-120 and 100-200 mesh).
General procedure for the synthesis of 1,2,3-triazole using click chemistry. A mixture of
azide (1.0 equiv.), alkyne (0.5 equiv.), CuSO4.5H2O (5 mol %) and NaAsc. (10 mol %) in a
mixture of THF and water (1:1) was stirred for 10 h at room temperature. The residue obtained
after evaporation of the solvent was washed thoroughly with water and dissolved in CHCl3 (150
mL). The organic layer was washed with water (2 x 100 mL) and brine (1 × 150 mL) and dried
(Na2SO4) and evaporated to give the crude triazole, which was purified by column
chromatography (SiO2).
1
Dendrimer 1 (G0). Yield 86%, mp 78 oC. H NMR (300 MHz, CDCl3): δH 1.20-1.25 (m, 8H),
1.77-1.86 (m, 8H), 4.24 (t, 4H, J = 6.9 Hz), 4.30 (t, 4H, J = 7.2 Hz), 5.20 (s, 4H), 5.26 (s, 4H),
6.76 (d, 4H, J = 8.1 Hz), 6.86-6.93 (m, 4H), 6.98-7.07 (m, 8H), 7.12 (d, 4H, J = 7.8 Hz), 7.26 (s,
13
4H), 7.55 (s, 2H), 7.58 (s, 4H), 7.69 (d, 2H, J = 15.9 Hz). C NMR (75 MHz, CDCl3): δC 25.6,
25.7, 29.8, 29.9, 44.9, 50.0, 50.1, 62.1, 115.2, 115.3, 122.3, 122.6, 122.8, 123.8, 123.9, 127.2,
127.3, 128.1, 130.1, 142.5, 143.7, 144.3, 144.9, 160.1, 188.8. ESI-MS: m/z = 1154 (M+H)+.
Anal. calcd. for C65H64N14O3S2: C, 67.68; H, 5.59; N, 17.00%. Found: C, 67.54; H, 5.67; N,
17.10%.
Dendrimer 2 (G1). Yield 84%, mp 100 oC. 1H NMR (300 MHz, CDCl3): δH 1.17-1.26 (m, 16H),
1.74-1.83 (m, 16H), 4.21 (t, 8H, J = 6.9 Hz), 4.24 (t, 8H, J = 6.9 Hz), 5.10 (s, 8H), 5.17 (s, 8H),
5.20 (s, 4H), 5.42 (s, 4H), 6.49 (d, 4H, J = 1.8 Hz), 6.61 (t, 2H, J = 2.1 Hz), 6.75 (d, 8H, J = 8.1
Hz), 6.84-6.90 (m, 12H), 6.95-7.04 (m, 16H), 7.08 (d, 8H, J = 7.5 Hz), 7.51 (s, 2H), 7.56 (s, 4H),
13
7.61 (s, 4H). C NMR (75 MHz, CDCl3): δC 25.5, 25.6, 29.7, 29.8, 44.9, 49.9, 50.0, 54.0, 61.9,
102.0, 107.4, 115.2, 122.3, 122.8, 123.1, 123.7, 123.8, 127.1, 127.3, 128.1, 130.1, 136.8, 142.4,
143.4, 143.9, 144.2, 144.7, 159.8, 160.0, 188.7. QTOF-MS: m/z = 2445.98 (M+). Anal. calcd. for
C133H132N34O7S4: C, 65.28; H, 5.44; N, 19.46%. Found: C, 65.42; H, 5.53; N, 19.38%.
Dendrimer 3 (G0). Yield 84%, mp 198 oC. 1H NMR (300 MHz, CDCl3): δH 1.19-1.33 (m, 8H),
1.77-1.88 (m, 8H), 3.06 (s, 4H), 4.23 (t, 4H, J = 6.9 Hz), 4.29 (t, 4H, J = 6.9 Hz), 5.19 (s, 4H),
5.26 (s, 4H), 6.76 (d, 4H, J = 8.1 Hz), 6.88 (t, 4H, J = 7.5 Hz), 7.01-7.06 (m, 8H), 7.09-7.12 (m,
4H), 7.27 (s, 2H), 7.54-7.57 (m, 8H). 13C NMR (75 MHz, CDCl3): δC 25.6, 25.7, 26.5, 29.8, 29.9,
44.9, 50.0, 50.1, 62.1, 115.1, 115.3, 122.3, 122.6, 122.8, 123.9, 127.2, 127.3, 129.3, 132.5, 133.1,
135.6, 143.8, 144.3, 144.9, 159.1, 196.2. ESI-MS: m/z = 1179.4 (M+H)+. Anal. calcd. for
C67H66N14O3S2: C, 68.23; H, 5.64; N, 16.63%. Found: C, 68.48; H, 5.53; N, 16.72%.
1
Dendrimer 4 (G0). Yield 85%, mp 172-174 oC. H NMR (300 MHz, CDCl3): δH 1.20-1.25 (m,
8H), 1.78-1.86 (m, 10H), 2.91 (t, 4H, J = 5.1 Hz), 4.24 (t, 4H, J = 7.2 Hz), 4.30 (t, 4H, J = 7.2
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Hz), 5.20 (s, 4H), 5.25 (s, 4H), 6.76 (d, 4H, J = 8.1 Hz), 6.89 (t, 4H, J = 7.5 Hz), 7.01-7.07 (m,
8H), 7.12 (d, 4H, J = 7.5 Hz), 7.27 (s, 2H), 7.44 (d, 4H, J = 8.7 Hz), 7.57 (s, 2H), 7.74 (s, 2H).
13C NMR (75 MHz, CDCl3): δC 22.7, 25.3, 25.4, 28.2, 29.5, 29.6, 44.6, 49.7, 49.8, 61.8, 114.4,
114.9, 122.0, 122.2, 122.5, 123.6, 126.9, 127.0, 128.9, 131.9, 134.3, 136.0, 143.6, 143.9, 144.6,
158.2, 189.7. ESI-MS: m/z = 1193.4 (M+H)+, m/z = 1215.6 (M+Na)+. Anal. calcd. for
C68H68N14O3S2: C, 68.43; H, 5.74; N, 16.43%. Found: C, 68.64; H, 5.87; N, 16.52%.
1
Dendrimer 5 (G1). Yield 80%, mp 142-144 oC. H NMR (300 MHz, DMSO-d6): δH 1.10-1.13
(m, 16H), 1.67-1.74 (m, 16H), 3.01 (s, 4H), 4.23-4.31 (m, 16H), 5.11 (s, 16H), 5.22 (s, 4H), 5.53
(s, 4H), 6.59 (d, 4H, J = 1.8 Hz), 6.72 (t, 2H, J = 1.8 Hz), 6.86-6.92 (m, 14H), 7.05-7.10 (m,
16H), 7.14 (d, 4H, J = 8.7 Hz), 7.38 (s, 2H), 7.63 (d, 4H, J = 8.7 Hz), 7.89 (s, 4H); 8.16 (s, 4H),
13
8.31-8.32 (m, 4H). C NMR (75 MHz, DMSO-d6): δC 24.9, 25.1, 25.9, 29.3, 29.4, 43.9, 49.1,
49.2, 52.8, 61.2, 79.1, 101.0, 107.2, 115.2, 115.6, 122.6, 123.2, 124.3, 124.8, 126.7, 127.4, 128.4,
131.9, 132.4, 132.8, 135.6, 138.0, 142.3, 142.6, 143.3, 144.0, 159.0, 159.4, 194.9. MALDI-TOF-
MS: m/z = 2472.2 (M+). Anal. calcd. for C135H134N34O7S4: C, 65.57; H, 5.46; N, 19.26%. Found:
C, 65.66; H, 5.54; N, 19.18%.
Dendrimer 6 (G1). Yield 86%, mp 104 oC. 1H NMR (300 MHz, CDCl3): δH 1.17-1.26 (m, 16H),
1.74-1.82 (m, 16H), 2.13-2.15 (m, 2H), 2.86 (t, 4H, J = 5.4 Hz), 4.19 (t, 8H, J = 6.9 Hz), 4.26 (t,
8H, J = 6.9 Hz), 5.09 (s, 8H), 5.16 (s, 8H), 5.18 (s, 4H), 5.41 (s, 4H), 6.49 (d, 4H, J = 1.5 Hz),
6.61 (t, 2H, J = 1.8 Hz), 6.74 (d, 8H, J = 7.8 Hz), 6.85 (t, 8H, J = 7.5 Hz), 6.97-7.01 (m, 10H),
7.04-7.09 (m, 10H), 7.28 (s, 4H), 7.40 (d, 4H, J = 8.7 Hz), 7.56 (s, 4H), 7.62 (s, 2H), 7.69 (s,
13
2H). C NMR (75 MHz, CDCl3): δC 22.8, 25.4, 25.5, 28.3, 29.6, 29.7, 30.8, 44.8, 49.8, 49.9,
53.9, 61.8, 101.9, 107.3, 114.6, 115.2, 122.2, 122.7, 122.8, 123.0, 123.7, 127.0, 127.2, 129.1,
132.1, 134.5, 136.1, 136.8, 143.3, 143.9, 144.1, 144.6, 158.4, 159.7, 189.9. MALDI-TOF-MS:
m/z = 2484 (M+). Anal. calcd. for C136H136N34O7S4: C, 65.68; H, 5.51; N, 19.15%. Found: C,
65.74; H, 5.64; N, 19.12%.
o
1
Dendrimer 7 (G0). Yield 92%, mp 88-90 C. H NMR (300 MHz, CDCl3): δH 1.09-1.13 (m,
8H), 1.56-1.60 (m, 4H), 1.70-1.75 (m, 4H), 3.98 (t, 4H, J = 6.3 Hz), 4.19 (t, 4H, J = 6.9 Hz), 5.07
(d, 2H, J = 12.6 Hz), 5.19 (s, 4H), 5.23 (s, 2H), 6.46 (s, 2H), 6.76 (d, 4H, J = 8.1 Hz), 6.86 (t,
4H, J = 7.5 Hz), 7.02 (t, 4H, J = 7.5 Hz), 7.09 (d, 4H, J = 6.9 Hz), 7.14-7.24 (m, 4H), 7.28 (s,
2H), 7.31-7.34 (m, 2H), 7.50 (d, 2H, J = 9.0 Hz), 7.86 (d, 2H, J = 8.1 Hz), 7.93 (d, 2H, J = 9.0
Hz). 13C NMR (75 MHz, CDCl3): δC 25.6, 29.7, 29.8, 44.9, 49.8, 50.0, 64.0, 115.3, 116.0, 120.7,
122.2, 122.4, 122.8, 123.9, 124.0, 125.4, 126.5, 127.2, 127.3, 127.9, 129.5, 129.6, 133.9, 144.3,
144.6, 144.8, 153.7. ESI-MS: m/z = 1174 (M+H)+. Anal. calcd. for C68H64N14O2S2: C, 69.60; H,
5.50; N, 16.71%. Found: c, 69.72; H, 5.67; N, 16.78%.
Dendrimer 8 (G1). Yield 83%, mp 98 oC. 1H NMR: (300 MHz, CDCl3): δH 1.20-1.29 (m, 16H),
1.75-1.77 (m, 16H), 4.11-4.25 (m, 16H), 4.96 (d, 2H, J = 12.9 Hz), 5.07 (s, 12H), 5.17 (s, 10H),
6.30 (s, 4H), 6.48 (s, 2H), 6.62 (s, 2H), 6.74 (d, 8H, J = 8.1 Hz), 6.86 (t, 8H, J = 7.5 Hz), 7.02 (t,
8H, J = 7.5 Hz), 7.08 (d, 12H, J = 6.6 Hz), 7.26 (s, 6H), 7.37 (d, 2H, J = 9.0 Hz), 7.59 (s, 4H),
13
7.77 (d, 2H, J = 8.4 Hz), 7.83 (d, 2H, J = 9.0 Hz). C NMR (75 MHz, CDCl3): δC 25.6, 25.7,
29.8, 29.9, 44.9, 50.0, 53.7, 61.9, 63.9, 101.7, 107.3, 115.3, 116.0, 120.7, 122.4, 122.8, 123.0,
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123.8, 123.9, 125.3, 126.5, 127.2, 127.3, 128.0, 129.5, 133.8, 137.0, 143.4, 144.3, 144.7, 144.9,
153.6, 159.8. MALDI-TOF-MS: m/z = 2466 (M)+. Anal. calcd. for C136H132N34O6S4: C, 66.21;
H, 5.39; N, 19.30%. Found: C, 66.14; H, 5.53; N, 19.24%.
Bromo dendron 11. Yield 90%, mp 112 oC. 1H NMR (300 MHz, CDCl3): δH 1.17-1.25 (m, 2H),
1.35-1.45 (m, 2H), 1.72-1.85 (m, 4H), 3.34 (t, 2H, J = 6.9 Hz), 4.27 (t, 2H, J = 6.9 Hz), 5.21 (s,
2H), 6.77 (d, 2H, J = 8.1 Hz), 6.90 (t, 2H, J = 7.5 Hz), 7.02-7.08 (m, 2H), 7.11-7.14 (m, 2H),
7.28 (s, 1H). 13C NMR (75 MHz, CDCl3): δC 25.4, 27.4, 29.9, 32.3, 33.4, 45.0, 50.2, 115.3,
122.3, 122.8, 123.9, 127.2, 127.3, 144.3, 144.8. ESI-MS: m/z = 444 (M+H)+. Anal. calcd. for
C21H23BrN4S: C, 56.88; H, 5.23; N, 12.64%. Found: C, 56.72; H, 5.46; N, 12.48%.
1
Dendritic chloride 14. Yield 89%, mp 218-220 oC. H NMR (300 MHz, CDCl3): δH 1.19-1.29
(m, 8H), 1.78-1.84 (m, 8H), 4.23 (t, 4H, J = 7.2 Hz), 4.28 (t, 4H, J = 7.2 Hz), 4.48 (s, 2H), 5.16
(s, 4H), 5.19 (s, 4H), 6.59 (t, 1H, J = 2.1 Hz), 6.63 (d, 2H, J = 2.1 Hz), 6.76 (d, 4H, J = 8.1 Hz),
6.85-6.90 (m, 4H), 7.01-7.12 (m, 8H), 7.28 (s, 2H), 7.56 (s, 2H). 13C NMR (75 MHz, CDCl3): δ-
C 25.6, 29.9, 41.7, 44.9, 49.4, 49.6, 50.0, 54.3, 61.8, 107.2, 115.3, 122.2, 122.6, 122.8, 123.8,
123.4, 127.1, 127.4, 143.4, 143.6, 144.2, 144.7, 159.1. ESI-MS: m/z = 1046.7 (M+H)+. Anal.
calcd. for C55H57ClN14O2S2: C, 63.17; H, 5.49; N, 18.75%. Found: C, 63.29; H, 5.58; N, 18.69%.
General procedure for the synthesis of dendritic azide from the dendritic chloride/bromide
To the corresponding alkyl chloride/bromide (1 mmol) dissolved in dry DMF (20 ml), sodium
azide (1.5 mmol) was added and stirring was continued at 60 ºC for 10 h. The reaction mixture
was then allowed to cool to room temperature. It was then poured into ice-cold water (30 mL)
and extracted with CHCl3 (3 × 100 mL). The organic layer was washed with water (100 mL) and
saturated NaCl (3 × 100 mL), dried (Na2SO4). Solvent was evaporated under reduced pressure to
afford the crude product, which was purified by column chromatography (SiO2).
1
Azido dendron 12. Yield 91%, mp 84-86 oC. H NMR (300 MHz, CDCl3): δH 1.17-1.36 (m,
4H), 1.47-1.54 (m, 2H), 1.77-1.85 (m, 2H), 3.21 (t, 2H, J = 6.9 Hz), 4.26 (t, 2H, J = 6.9 Hz), 5.21
(s, 2H), 6.76 (d, 2H, J = 8.1 Hz), 6.90 (t, 2H, J = 7.5 Hz), 7.02-7.05 (m, 2H), 7.08-7.14 (m, 2H),
7.28 (s, 1H). 13C NMR (75 MHz, CDCl3): δC 25.8, 26.0, 28.6, 29.9, 45.0, 50.2, 51.2, 115.3,
122.3, 122.8, 123.9, 127.2, 127.3, 144.3, 144.8. ESI-MS: m/z = 406 (M+H)+. Anal. calcd. for
C21H23N7S: C, 62.20; H, 5.72; N, 24.18%. Found: C, 62.04; H, 4.87; N, 24.09%.
Dendritic azide 15. Yield 87%, mp 106 oC. 1H NMR (300 MHz, CDCl3): δH 1.11-1.18 (m, 8H),
1.56-1.85 (m, 8H), 4.11-4.21 (m, 10H), 5.08 (s, 4H), 5.10 (s, 4H), 6.47 (d, 2H, J = 1.8 Hz), 6.53
(t, 1H, J = 2.1 Hz), 6.67 (d, 4H, J = 8.1 Hz), 6.79 (t, 4H, J = 7.2 Hz), 6.94 (t, 4H, J = 7.5 Hz),
13
7.01 (d, 4H, J = 7.5 Hz), 7.19 (s, 2H), 7.49 (s, 2H). C NMR (75 MHz, CDCl3): δC 25.4, 25.6,
29.7, 29.8, 44.8, 49.8, 49.9, 54.5, 61.9, 101.6, 107.4, 115.1, 122.2, 122.6, 122.7, 123.7, 127.0,
127.2, 137.7, 143.6, 144.1, 144.6, 159.5. ESI-MS: m/z = 1052 (M+H)+. Anal. calcd. for
C55H57N17O2S2: C, 62.78; H, 5.46; N, 22.63%. Found: C, 63.69; H, 5.52; N, 22.69%.
General procedure for synthesis of acetylenic enone core. A mixture of the corresponding
phenol (1.0 equiv.), propargyl bromide (1.25 equiv.) and anhydrous potassium carbonate (3.0
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ARKIVOC 2014 (iv) 67-79
equiv.) in dry DMF (15 mL) was stirred at 60 oC for 24 h. The reaction mixture was then allowed
to cool to room temperature and poured into ice water. The resulting precipitate was filtered,
washed thoroughly with water and dissolved in CHCl3 (150 mL). The organic layer was washed
with water (2 x 100 mL) and brine (1 × 150 mL), dried (Na2SO4) and evaporated to give the
crude dendron, which was purified by column chromatography (SiO2).
o
1
Bis(propargyloxy)dienone 19. Yield 63%, mp 83 C. H NMR (300 MHz, CDCl3): δH 2.56 (t,
2H, J = 2.1 Hz), 4.74 (d, 4H, J = 2.1 Hz), 6.93 (s, 2H), 7.01 (d, 4H, J = 9.0 Hz), 7.58 (d, 4H, J =
8.7 Hz), 7.69 (d, 2H, J = 15.0Hz). 13C NMR (75 MHz, CDCl3): δC 55.9, 76.0, 78.6, 114.9, 115.3,
123.9, 128.5, 130.0, 142.5, 159.4, 188.8. ESI-MS: m/z = 343 (M+H)+. Anal. calcd. for C23H18O3:
C, 80.68; H, 5.30%. Found: C, 80.56; H, 5.38%.
Bis(propargyloxy)pentanone 20. Yield 82%, mp 172 oC. 1H NMR (300 MHz, CDCl3): δH 2.56
(t, 2H, J = 2.4 Hz), 3.09 (s, 4H), 4.75 (d, 4H, J = 2.4 Hz), 7.05 (d, 4H, J = 8.7 Hz), 7.56-7.60 (m,
13
6H). C NMR (75 MHz, CDCl3): δC 26.4, 55.8, 75.9, 78.1, 115.2, 129.6, 132.4, 133.1, 135.7,
158.4, 196.2. ESI-MS: m/z = 369 (M+H)+. Anal. calcd. for C25H20O3: C, 81.50; H, 5.47%.
Found: C, 81.58; H, 5.52%.
o
Bis(propargyloxy)hexanone 21. Yield 76%, mp 152-154 C. H NMR (300 MHz, CDCl3): δH
1
1.79 (m, 2H), 2.55 (t, 2H. J = 2.1 Hz), 2.91 (t, 4H, J = 5.4 Hz), 4.73 (d, 4H, J = 2.1 Hz), 7.51 (d,
13
4H, J = 8.7 Hz), 7.45 (d, 4H, J = 8.7 Hz), 7.75 (s, 2H). C NMR (75 MHz, CDCl3): δC 23.0,
28.5, 55.8, 75.9, 78.2, 116.2, 128.5, 129.6, 134.7, 136.4, 157.7, 190.2. ESI-MS: m/z = 383
(M+H)+. Anal. calcd. for C26H22O3: C, 81.65; H, 5.80%. Found: C, 81.58; H, 5.86%.
Supplementary Material
1H, 13C NMR and Mass spectra for dendrimer 2 and 4 are available.
Acknowledgements
The authors thank DST-FIST for providing NMR facilities to the Department of Organic
Chemistry, University of Madras. CSK thank CSIR for the award of Senior Research Fellowship
(SRF).
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ARKIVOC 2014 (iv) S1-S4
Supplementary Materials
Synthesis and photophysical studies on triazole bridged dendrimers
with phenothiazine as surface unit
Perumal Rajakumar,* Chinnadurai Satheeshkumar, and Mahalingam Ravivarma
Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 25, India
E-mail: perumalrajakumar@gmail.com
Table of Contents
1. 1H NMR Spectrum (300 MHz, CDCl3) of dendrimer 2
2. 13C NMR Spectrum (75 MHz, CDCl3) of dendrimer 2
3. Mass (QTOF) spectrum of dendrimer 2
S2
S2
S3
S3
S4
S4
4. 1H NMR Spectrum (300 MHz, CDCl3) of dendrimer 4
5. 13C NMR Spectrum (75 MHz, CDCl3) of dendrimer 4
6. Mass (ESI) spectrum of dendrimer 4
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S
S
N
N
N
N
N
N
N
N
(CH2)
(CH2)
6
6
O
N
N
N
N
N
N
O
O
O
O
N
N
N
N
N
N
O
O
N
N
N
N
N
N
(CH2
)
(CH2)
6
6
N
N
N
N
N
N
N
N
S
S
2
Figure S1. 1H NMR Spectrum (300 MHz, CDCl3) of dendrimer 2
S
S
N
N
N
N
N
N
N
N
(CH2)
(CH2
)
6
6
O
N
N
N
N
N
N
O
O
O
O
N
N
N
N
N
N
O
O
N
N
N
N
N
N
(CH2
)
(CH2)
6
6
N
N
N
N
N
N
N
N
S
S
2
Figure S2. 13C NMR Spectrum (75 MHz, CDCl3) of dendrimer 2
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2445.98 (M+)
S
S
N
N
N
N
N
N
N
N
(CH2)
(CH2)
6
6
O
N
N
N
N
N
N
O
O
O
O
N
N
N
N
N
N
O
O
N
N
N
N
N
N
(CH2
)
6
(CH2)
6
N
N
N
N
N
N
N
N
S
S
2
Figure S3. Mass (QTOF) spectrum of dendrimer 2
O
O
O
N
N
N
N
N
N
(CH2
)
6
(H2C)6
N
N
N
N
N
N
N
N
S
S
4
Figure S4. 1H NMR Spectrum (300 MHz, CDCl3) of dendrimer 4
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ARKIVOC 2014 (iv) S1-S4
O
O
O
N
N
N
N
N
N
(CH2
)
6
(H2C)6
N
N
N
N
N
N
N
N
S
S
4
Figure S5. 13C NMR Spectrum (75 MHz, CDCl3) of dendrimer 4
1215.60 (M+Na)+
O
O
O
N
N
N
N
N
N
(CH2
)
6
(H2C)6
N
N
N
N
N
N
N
N
4
S
S
1193.40 (M+H)+
Figure S6. Mass (ESI) spectrum of dendrimer 4
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