An efficient and controlled synthesis of persulfonylated G1 dendrimers: Via click reaction

Article abstract of DOI:10.1039/c6ra09929g

This work presents the first report, we believe, on controlled synthesis of clickable dendrimers using aromatic and heteroaromatic cores and persulfonylated dendrons. Owing to poor thermal stability of persulfonylated dendrons, CuAAC reaction conditions w

Full text of DOI:10.1039/c6ra09929g

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An Efficient and Controlled Synthesis of Persulfonylated
G1 Dendrimers Via Click Reaction
Shaziya Khanam,† Sunil K. Rai,† Deepshikha Verma‡, Ranjana S. Khanna† and Ashish K.
Tewari†*
†Department of Chemistry (Center of Advanced Study), Institute of Science, Banaras Hindu University, Varanasiꢀ
221005, India.
‡
Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai
400005, India
*Email: tashish2002@yahoo.com
ABSTRACT: This work presented the first report on controlled synthesis of clickable
dendrimers using aromatic and heteroaromatic cores and persulfonylated dendrons. Due to poor
thermal stability of persulfonylated dendrons, CuAAC reaction condition was standardized at the
room temperature. Click reactions went smoothly with Cu(PPh3)3Br complex in the presence of
tridentate chelating ligands and produced copper free G1 dendrimers in excellent yield. This
methodology has now unveiled the peripheral decoration of high generation POPAM dendrimers
with persulfonyl group in one step click reaction.
Introduction
Synthesis of bioꢀinspired molecules has fascinated the recent research activities. Among them
synthesis of macromolecules with biologically active scaffold is of paramount interest.1ꢀ3

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Furthermore, recent year has witnessed unprecedented growth of research in the area of
dendrimer synthesis for their application in the field of biomedical science4,5 and nanoscience6,7.
Consequently, development of dendrimers with wellꢀdefined size and shape is of eminent
interest because macromolecular dendritic species generally suffer from structural imperfections
and polydispersity.9 However, the synthesis of dendritic molecules is an apparently straight
forward iterative process,10,11 yet, production of high generation dendrimers in good yield with
high purity is challenging. To overcome this issue, click reactions are being used for the
magnificent yield of dendrimers.12,13 The azide and alkyne based click reactions incorporates
1,2,3ꢀtriazole ring in the branching positions of the dendrimers. Since triazoles are efficient
ligand for Cu(I) complexation, therefore, selection of catalyst and ligand is a challenging task.14ꢀ
15
Moreover, functionalization of dendrimers at the perifery via N,Nꢀbisꢀsulfonylation with
various sulfonyl chlorides has been developed as a controlled and selective functionalization, but
the difficulty arose with peripheral pꢀnitro benzenesulfonyl (pꢀNs or nosyl) functional groups
which convert back into corresponding amines.16ꢀ18 No doubt, due to commercial availability of
oligoꢀamines, POPAM and PAMAM dendrimers, these have often been decorated at their
periphery with diverse groups aiming at the introduction of a specific function and consecutive
dendrimer growth.19 This was usually restricted to the complete functionalization at each of the
peripheral amino groups. Therefore, such functionalization often lacks the selectivity and a
monodisperse product.9,16 Despite this, the groundwork on sulfone based clickable dendrimers is
yet not reported in literature and its synthetic exploration is crucial.

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Results and Discussion
In this preliminary work we have synthesized alkyne functionalized aromatic and heteroaromatic
cores (Scheme 1) and azide functionalized persulfonylated termini (Scheme 2). Subsequently,
the obtained azide functionalized dendrons and alkyne functionalized cores were stitched
together via Cu(I)ꢀcatalyzed AzideꢀAlkyne Cycloaddition (CuAAC) reaction. Since pꢀnosyl
amines are thermally unstable, therefore, reaction condition for the click reaction has been
standardized at the ambient temperature. Although, mere triethylamine is capable of stabilizing
the copper(I) active species even in reactions carried out ‘on water’ yet the selection of
appropriate ligand and solvent is consequential in the synthesis of macromolecues.20,21 Table 1
shows the screening of copper catalyst and nitrogen containing ligands/bases. Inasmuch the
triazole ring constructed in the click reaction itself have capability to form stable copper complex
in the reaction media, therefore, use of nitrogen containing ligands/bases as an additive must be
having the higher affinity towards stable copper complexation than the generated triazole ring in
the reaction. It was observed that in the presence of CuI and monodentate ligands yield of D2
was very low while D6 was negligible. Lower yield of both the dendrimers revealed that
generated dendrimers formed stable copper complexes than the DIPEA. Therefore, we checked
the yield of dendrimers under same condition by adding CuI form 0.3 mole % to 10 mole % but
yield was not improved satisfactorily. Subsequently, use of tridentate chelating ligands such as
tris(benzyltriazolylmethyl)amine
(TBTA),
N,N,N′,N′′,N′′ꢀpentamethyldiethylenetriamine
(PMDTA), tris(2ꢀbenzimidazolylmethyl)amine (BimH)3, Tris(2ꢀpyridylmethyl)amine (TPMA)
and tris[2ꢀ(dimethylamino)ethyl]amine (Me6TREN) produced up to 80ꢀ85 % yield with only 0.3
mole % of CuI.22ꢀ23 It was observed that use of less hindered ligands lowered the yield of D8
while hindered ligands improved the yield as well as lowered the reaction time. After screening

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the ligands with CuI, click reaction was tested with Cu(PPh3)3Br. It is well known in the
literature that PPh3 improve the solubility of the catalyst in the reaction solvent (i.e. DCM)
therefore it allowed for comparatively lower copper loadings. Consequently, dendrimers
obtained with Cu(PPh3)3Br / TPMA or Me6TREN are highly pure and copper free.
Scheme 1. Synthesis of Alkyne Terminated Clickable Core Molecules 1a, 2a and 3a-c
Scheme 2. Synthesis of Azide Functionalized Persulfonylated Dendrons 5a-c

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Table 1. Screening of Catalysts and Additives for CuAAC Reaction of Dendron and Core
Molecules
S. No.
Catalyst
Solvent
Additive
Time
(h)
Yield (%) a
D2/D8
(0.3 mol%)
(0.3 mol%)
CuSO4.5H2O
CuI
THF/H2O
THF
NaAsc
DIPEA
DIPEA
DBU
24
24
24
24
8
trace
10/trace
30/5
1.
2.
CuI
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
3.
CuI
23/trace
55/20
65/60
50/32
85/82
85/80
35/trace
50/30
90/88
98/95
99/97
4.
CuI
TBTA
5.
CuI
PMDTA
(BimH)3
TPMA
8
6.
CuI
8
7.
CuI
3
8.
CuI
Me6TREN
None
3
9.
Cu(PPh3)3Br
Cu(PPh3)3Br
Cu(PPh3)3Br
Cu(PPh3)3Br
Cu(PPh3)3Br
24
8
10.
11.
12.
13.
14.
DIPEA
PMDTA
TPMA
4
1
Me6TREN
1
aIsolated yield has been reported. Since loss of sulfonyl group was common in these reactions
therefore 1H NMR did not predict the exact percent conversion of the products.

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The scope of this reaction was then explored on various dendrons and cores (Scheme 3). The
use of alkyne terminated simple cores (1a, 2a and 3a) and hypercores (3b and 3c) did not affect
the reaction rate, except bisꢀnosyl dendron (5c) which showed poor reactivity perhaps due to
least stability under reaction condition. To our knowledge, this is the first time that a
persulfonylated clickable dendrimers have been designed and structural purity of the G1ꢀ
dendrimers were fully confirmed by means of NMR, GPC and MALDIꢀTOF spectrometry. From
1
the H and 13C NMR spectra it is clear that all dendrimers possessed almost symmetrical
structures in their solution phase (see in supporting information). Although dendrimers are often
Scheme 3. Synthesized Persulfonylated Dendrimers D1-12

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Figure 1. GPC curves of D1ꢀD6 (upper) and D7ꢀD12 (below) after purification.
described as a polymer with excellent PDI (as low as 1.01), this is obtained only after extensive
purification. The structural heterogeneity arose from undesired sideꢀreactions during synthesis
directly affect the weightꢀaverage (Mw) molecular weight, and PDI of the dendrimers.
Therefore, GPC analysis was performed after purification by column chromatography. GPC
analysis (Figure 1) determined the wellꢀdefined molecular structure for all the dendrimers with a
low polydispersity ranging from 1.01 to 1.03. The Mw of the dendrimers increases from D1 =
1239 to D12 = 2880 and their retention time varies from 21.00 to 19.85 minutes.

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Matrixꢀassisted laser desorption/ionization time of flight (MALDIꢀTOF) mass spectrometry
is frequently used for the dendrimer characterization due to the common coupling to timeꢀofꢀ
flight analyzers that offer a broad mass range. Although, MALDIꢀMS may point to the presence
of large amounts of defects, because they may be formed during laser irradiation.24 The
wavelength of the light required for photocleavage of sulfonamides falls in the UV range (i.e.
254 nm) which is far below the wavelength of the N2 laser of MALDI instrument (i.e. 337 nm).
But photochemical cleavage of the S−N bonds cannot be ignored at all because UV spectra of the
dendrons show absorption around 330ꢀ336 nm and thus it has possibility to absorb light energy
from the MALDI laser. To show the clear evidence for synthetic advantage of the catalysts, it has
been tried to isolate the dendrimers with and without copper complex. To our great delight,
purification of D4 obtained by CuI catalyst delivered the D4 with copper. The structurally
perfect dendrimer appears with quite intense signals along with loss of SO2 from parent ion with
quite low intensity (Figure 2 left). Interestingly, the copper bounded D4 shows intense signal at
[M+Cu+H]+ and second intense signal at [M+2Cu+H]+ followed by low intense signals at
[M+CuꢀTs+H]+and [M+2Cuꢀ3Ts+H]+ (Figure 2 middle). The tentative mechanism for the loss of
SO2 and tosylsulfinic acid has been shown in Figure 2 (right). The most striking results came
from MALDI is the photochemical cleavage of the S−N bonds. The copper free dendrimer losses
only SO2 keeping other parts of the molecule connected to each other through intramolecular
ipso substitution in a concerted mechanism, while copper bounded dendrimer goes for
detosylation through 1,2ꢀelimination reactions.17

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Figure 2. MALDIꢀTOF mass spectra of D4 without copper complex (left) and with copper
complex (middle) and tentative mechanism for the loss of SO2 (right upper) and Ts (right lower).
Conclusions
Overall, it can be concluded that we have developed an efficient and highly controlled reaction
condition for the synthesis of peripheral persulfonylated dendrimers via CuAAC reaction at room
temperature. Yield of persulfonylated dendrimers in CuI catalyzed reactions were very low or in
trace amount with DIPEA and DBU but addition of tridentate chelating ligands improved the
yield to some extent as well as reduced the reaction time. Therefore, it can be estimated that the
in situ generated dendrimers worked as competitive ligands for the copper center. Eventually we
find Cu(PPh3)3Br with TPMA or Me6TREN as an excellent catalyst for the production of copper
free dendrimers. Further, GPC analysis revealed that all dendrimers are monodisperse with PDI
= 1.01 ꢀ 1.3. However, MALDI evinced the molecular perfection of the dendrimers with intense
signals at [M+H]+. After successful development of peripheral persulfonylated dendrimers with
high molecular perfection, now decoration of higher generation POPAM dendrimer at periphery

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would be easy. Consequently, we are now developing the higher generation POPAM based
persulfonylated clickble dendrimers using this methodology.
EXPERIMENTAL SECTION
General Considerations. All reagents and solvents used were of pure analytical grade. The
glassware used in the experiments was carefully cleaned and oven dried. Completion of reaction
was checked by commercially available thin layer chromatography (TLC) from Merck, made up
of silica gel 60/Kieselguhr F254 precoated on Aluminum sheets (thickness 0.2 mm). Column
chromatography was performed using Merck silica gel (100ꢀ200 mesh). Visualization of spots on
TLC plate was accomplished with UV light. Products yield refer to either crude or isolated yield
13
after column chromatography. 1H and C NMR spectra were recorded at 300 or 500 and 75 or
125 MHz spectrometers, respectively, using the internal standard tetramethylsilane (TMS).
Chemical shifts are given in parts per million, and J values are in hertz. Matrixꢀassisted laser
desorption ionization timeꢀofꢀflight mass spectrometry (MALDIꢀTOF MS) was performed with
Brukere ultraflextreme, equipped with smart beam technology and 2,5ꢀdihydroxybenzoic acid
(DHB) matrix. The numberꢀaverage molecular weight (Mn) and polydispersity index (Mw/Mn)
were determined in THF at 40 °C with a flow rate of 0.5 mL/min on two polystyrene gel
columns. The columns were calibrated against seven polystyrene standard samples. Electronic
absorption spectra were obtained in airꢀequilibrated solvents at room temperature.
Synthesis of core molecules: Compounds 1a, 2a 3a, 3b, 3c iia and iib were synthesized
according to literature methods. 25ꢀ30

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1,3,5-tris(prop-2-yn-1-yloxy)benzene (1a): In a 100 mL round bottomed
flask phloroglucinol (1.0 g, 7.93 mmol) and K2CO3 (3.3 g, 23.79 mmol)
were dissolved in DMF and stirred for 10 min at room temperature.
Afterward, propargyl bromide (2.5 mL, 27.75 mmol) was added. and
stirring was continued for further 24 h. Completion of reaction was checked with TLC. After
completion of reaction, it was poured into a beaker containing ice cold water with continuous
stirring and kept at 0ꢀ5 °C for precipitation. After getting a proper amount of precipitate, it was
filtered and dried in air. White solid; Yield 1.90 g (99%); IR (νmax/cmꢀ1) 3394, 3165, 2214, 1694,
1
1584; H NMR (300 MHz, CDCl3) δH 6.27 (s, 3 H, ArꢀH), 4.64 (s, 6 H, ꢀO-CH2), 2.53 (s, 3 H,
alkyne ꢀCH); 13C NMR (75 MHz, CDCl3) 160.6, 94.30, 74.9, 48.2; Chemical Formula:
C15H12O3, Elemental Analysis: Calculated; C, 74.99; H, 5.03; Found; C, 74.94; H, 5.06.
2,4,6-tris(prop-2-yn-1-ylthio)-1,3,5-triazine (2a): It was synthesized
according to the method used in the synthesis of 1a. But phloroglucinol was
replaced by thiocyanuric acid. Yellow solid; Yield 2.00 g (97%); IR (νmax/cmꢀ
1
1) 3447, 3176, 2208, 1698, 1583; H NMR (300 MHz, CDCl3) δH 3.98 (s, 6
13
H, ꢀSꢀCH2), 2.22 (s, alkyne ꢀCH); C NMR (75 MHz, CDCl3) 178.3, 80.3, 71, 29.2; Chemical
Formula: C15H12S3, Elemental Analysis: Calculated; C, 49.46; H, 3.11; N, 14.42; S, 33.01
Found; C, 49.45; H, 3.10; N, 14.42; S, 33.00
N2,N4,N6-tri(prop-2-yn-1-yl)-1,3,5-triazine-2,4,6-triamine (3a): In a round
bottomed flask 1:1 mixture of THF and methanol (20/20 mL) was cooled
down to 0ꢀ5 °C then cyanuric chloride (3.0 g, 16.27 mmol) was dissolved by
slow addition so that temperature of the solution remain at 0ꢀ5 °C. In a
conical flask containing THF at 0ꢀ5 °C, propargyl amine (3.30 mL, 16.27 mmol) was added.

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Then solution of propargyl amine in THF was added to the cyanuric chloride solution in drop
wise fashion. The obtained reaction mixture was treated with solution of NaHCO3 (4.10 g, 16.27
mmol) in THF (10 mL) at 0ꢀ5 °C to neutralize the solution. Then it was stirred at room
temperature for 1 hour with subsequent refluxing for 1.5 hours. After conformation of the
completion of the reaction with TLC, solvent was evaporated in reduced pressure. The obtained
crude solid was reꢀdissolved in THF and undissolved impurities were filtered out. Afterward,
THF was evaporated from the filtrate and pure compound (3a) was obtained. Yellow solid; Yield
1
3.9 g (99%); m.p. 147ꢀ149 °C; IR (νmax/cmꢀ1) 3426, 3338, 2853, 1586, 1475; H NMR (300
13
MHz, DMSOd6) δH 8.25 (s, 3 H, ꢀNH) 3.98 (s, 6 H, ꢀN-CH2), 2.49, (s, 3 H, alkyne ꢀCH); C
NMR (75 MHz, DMSOd6) 165.4, 82.3, 72.1, 29.2; Chemical Formula: C15H15N3, Elemental
Analysis: Calculated; C, 59.99; H, 5.03; N, 34.98;. Found; C, 59.92; H, 5.05; N, 34.97.
1-nitro-4-(prop-2-yn-1-yloxy)benzene (iia): 4ꢀnitrophenol (2.0 g, 12.89 mmol)
was reacted with propargylbromide (1.9 mL, 21.57 mmol), and K2CO3(2.17 g,
25.79 mmol) in DMF (20 mL) according to synthetic procedure of 1a. Pure
compound iia was isolated as a crystalline light yellow solid; Yield 2.5 g (98%);
1
IR (νmax/cmꢀ1) 3290, 2980, 2112, 1524, 1330; H NMR (300 MHz, CDCl3) δH 8.23 (d, 2 H, J =
9.3 Hz, Ar–H), 7.15 (d, 2 H, J = 9 Hz, Ar–H), 4.82 (s, 2 H, -CH2), 2.58, (s, 1 H, alkyne ꢀCH);
13C NMR (75 MHz, CDCl3) 150.8, 139.2, 136.1, 125.2, 119.0, 115.6, 74.5, 72.5, 57.0; Chemical
Formula: C9H7NO3, Elemental Analysis: Calculated; C, 61.10; H, 3.95; N, 7.90; Found; C,
61.02; H, 3.98; N, 7.91.
4-nitro-1,2-bis(prop-2-yn-1-yloxy)benzene (iib). 3, 4ꢀdihydroxycatachol (2
g, 12.89 mmol) was reacted with propargylbromide (3.5 mL, 28.37 mmol),

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and K2CO3 (2.17 g, 25.79 mmol) in DMF (20 mL) according to synthetic procedure of 1a. Pure
compound iib was isolated as a light yellow solid; Yield 2.8 g (98 %); Mp.= 107°C; IR (νmax/cmꢀ
1
1) 3298, 2986, 2118, 1521, 1335; H NMR (300 MHz, CDCl3) δH 7.98 (d, 1 H, J = 9 Hz, Ar–H),
7.28 (s, 1 H, Ar–H), 7.15 (d, 1 H, J = 8.6 Hz, Ar–H), 4.90 (s, 4 H, CH2), 2.62, ( s, 2 H, alkyne
13
CH); C NMR (75 MHz, CDCl3) 152.7, 139.2, 136.1, 135.1,128.2, 119.0, 118.3, 112.6, 109.6
105.8, 72.5, 59.2, 57.0; Chemical Formula: C12H9NO4, Elemental Analysis: Calculated; C,
62.34; H, 3.92; N, 6.06; Found; C, 62.31; H, 3.91; N, 6.04.
4-(prop-2-yn-1-yloxy)aniline (iiia): In a 100 mL round bottomed flask compound
iia (2 g, 11.29 mmol) was dissolved in 20 mL DCM/Ethanol (1:1) mixture. Then a
solution of SnCl2.H2O (3.52 g, 16.93 mmol) in 37% HCl was added and reaction
mixture was stirred at 40 °C for 4 h. After completion of the reaction it was poured
into 300 mL of deionized water and extracted with CH2Cl2 (2 × 200 mL). The combined organic
layers were washed with water followed by saturated NaHCO3. The isolated organic layer was
dried over anhydrous Na2SO4. Then solvent was removed under reduced pressure and the
resulting solid residue was dried in air. A viscous yellow product was obtained; Yield 1.32g
1
(79%); IR (νmax/cmꢀ1) 3490, 2880, 2115, 1330, 1208; H NMR (300 MHz, CDCl3) δH 6.85 (d, 2
H, J = 8.6 Hz, Ar–H), 6.64 (d, 2 H, J = 8.9 Hz, Ar–H), 5.62 (br, 2 H, NH2), 4.65 (s, 2 H, ꢀCH2),
13
2.49, ( s, 1 H, alkyne -CH); C NMR (75 MHz, CDCl3) 139.0, 137.1, 115.2, 112.6, 72.5, 70.1,
56.2; Chemical Formula: C9H9NO, Elemental Analysis: Calculated; C, 73.45; H, 6.16; N,
9.52; Found; C, 73.40; H, 6.18; N, 9.60.
3,4-bis(prop-2-yn-1-yloxy)aniline (iiib): It was also synthesized in the same
procedure as given in synthesis of compound (iiia). It is a brown viscous

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1
product; Yield 1.8g (98%); IR (νmax/cmꢀ1) 3543, 3459, 3291, 2919, 1614, 1266; H NMR (300
MHz, DMSOd6) δH 10.10 (s, 2H, NH2), 7.21 (d, 1 H, J = 7.2 Hz, Ar–H), 7.04 (s,1 H, Ar–H), 6.96
13
(d,1 H, Ar–H), 4.87 (s, 4 H, ꢀCH2), 3.62 (s, 6 H, alkyne -CH); C NMR (75 MHz, DMSOd6)
148.2, 147.3, 146.2, 125.4, 115.8, 114.9, 109.4, 56.3; Chemical Formula: C12H11NO2,
Elemental Analysis: Calculated; C, 71.63; H, 5.51; N, 6.96; Found; C, 71.65; H, 5.48; N, 6.98.
N2,N4,N6-tris(4-(prop-2-yn-1-yloxy)phenyl)-1,3,5-triazine-2,4,6-
triamine (3b): Synthetic procedure was same as in 3a. But the refluxing
time was 10ꢀ12 h. The reactants and product stoichiometry was as
follows; Compound iiia (2.25 g, 16.27 mmol) in THF (20mL), cyanuric
chloride (1.0 g, 5.42 mmol) in THF/methanol (10/10 mL) mixture and NaHCO3 (2.25 g, 16.27
mmol). The solid product was obtained. Light brown solid; Yield 2.7 g (96%); IR (νmax/cmꢀ1)
1
3282, 3250, 2925, 2119, 1592; H NMR (300 MHz, CDCl3) δH 7.50 (d, 6 H, J = 8.4 Hz, Ar–H),
7.44 (s, 3 H, NH) 7.32 (d, 6 H, J = 8.1 Hz, Ar–H), 4.70 (s, 6 H, CH2), 2.51 (s, 3 H, alkyne -CH);
13C NMR (75 MHz, CDCl3) 165.5, 148.2, 147.6, 146.2, 135.2, 121.9, 115.2, 79.4, 78.5, 56.0;
Chemical Formula: C30H24N6O3, Elemental Analysis: Calculated; C, 69.76; H, 4.68; N, 16.27;
Found; C, 69.78; H, 4.65; N, 16.22.
Compound 3c: Cyanuric chloride (1.0 g, 5.42 mmol) was reacted with
compound iiib (3.27 g, 16.27 mmol) and NaHCO3 (3.0 g, 16.27 mmol) in
THF/ methanol (2:1) mixture according to synthetic procedure of
compound 3b. Pure compound 3c was isolated as a brown solid; Yield
1
3.0 g (81.5%); IR (νmax/cmꢀ1) 3382, 3286, 2923, 2852, 1586, 1391; H NMR (300 MHz,
DMSOd6) δH 9.95 (s, 3 H, NH), 7.20 (d, 3 H, J = 8.7 Hz), 7.15 (s, 3 H), 7.04 (d, 3 H, J = 8.7 Hz,
13
Ar–H), 4.75 (s, 6 H, CH2), 4.54 (s, 6 H, CH2), 3.75 (s, 3 H, CH), 3.51(s, 3 H, alkyne CH); C

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NMR (75 MHz, DMSOd6) 163.8, 146.8, 143.4, 132.4, 114.8, 109.0, 104.8, 79.8, 78.9, 56.4;
Chemical Formula: C39H30N6O6, Elemental Analysis: Calculated; C, 69.02; H, 4.46; N, 12.38;
Found; C, 69.04; H, 4.50; N, 12.40.
Synthesis of Dendrons: Mono/bisꢀsulfonylation and azidation have been done according to
literature methods.31ꢀ33 Dendrons 5a-c were synthesized in three steps as shown in Scheme 2.
Step-1: Nosyl/tosylchloride (1 eq.) was added to
a
stirred solution of 2ꢀ
bromoethylaminehydrobromide (1 eq.) in pyridine and stirring was continued for next 2ꢀ3 h at
room temperature. After completion of the reaction ice cold water was added until precipitation
was completed. Then obtained precipitate was filtered and dried at room temperature.
Step-2: In this step azidation of mono nosyl/tosyl products (4b/4a)34,35 were done. For this
purpose, 4b/4a (1 eq.) were dissolved in water/acetone mixture (1:4) and to it NaN3 (1.5 eq.) was
added. Reaction mixture was stirred at 60 °C for 6ꢀ7 h. After completion of the reaction excess
amount of water was added at room temperature then kept at 0 °C for 4 h. Thereupon crystalline
precipitate was filtered and air dried.
Step-3: In this step persulfonylation was done. For this purpose azide derivative of mono
nosyl/tosyl products (1 eq.) and TEA (4 eq.) were dissolved in dry DCM. In another beaker
sulfonyl chloride derivatives (4 eq.) were dissolved in DCM and added to the previous solution
by stirring under argon atmosphere. After complete addition, reaction mixture was refluxed for
3ꢀ4 h. After completion of the reaction solvent was removed under reduced pressure and desired
products were purified by column chromatography.

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Compound 4c: Compound 4a (2.5 g, 8.99 mmol) was reacted with sodium azide
(1.8 g, 17.97 mmol) according to step 2. White crystalline solid; Yield 2.0 g
(92%); m.p. 180ꢀ185 °C; IR (νmax/cmꢀ1) 3441, 3346, 2244, 1693, 1602, 1509,
1344; 1H NMR (300 MHz, CDCl3) δH 7.77 (s, 2 H, J = 8.6 Hz, ArꢀH), 7.34 (d, 1
H, J = 8.8 Hz, ArꢀH), 4.87 (s, 1 H, ꢀNH), 3.41 (t, 2 H, J = 6.0 Hz, ꢀCH2), 3.11 (t, 2 H, J = 6 Hz, ꢀ
13
CH2), 2.43 (s, 3 H, CH3); C NMR (75 MHz, CDCl3) 143.8, 136.6, 129.8, 127.0, 50.8, 42.2,
21.5; Chemical Formula: C10H7N3O3, Elemental Analysis: Calculated; C, 55.30; H, 3.25; N,
19.35;. Found; C, 55.28; H, 3.26; N, 19.36.
Compound 4d: Compound 4b (2.5 g, 8.09 mmol) was reacted with sodium azide
(1.8 g, 16.17 mmol) according to step 2. Yellow crystalline solid; Yield 2.0 g
1
(91%); m.p. 136ꢀ140 °C; IR (νmax/cmꢀ1) 3449, 2952, 2107, 1594, 1363; H NMR
(300 MHz, CDCl3) δH 8.36 (d, 2 H, J = 8.4 HZ, ArꢀH), 7.86 (d, 4 H, J = 8.6 HZ,
13
Ar-H), 5.04 (s, 1 H, ꢀNH), 3.55 (t, 2 H, J = 6.0Hz, ꢀCH2), 3.38 (t, 2 H, J = 6 Hz, -CH2); C
NMR (75 MHz, CDCl3) 150.2, 144.4, 128.4, 124.5, 51.1, 41.80; Chemical Formula:
C8H9N5O4S, Elemental Analysis: Calculated; C, 35.42; H, 3.34; N, 25.82; S, 11.82 Found; C,
35.45; H, 3.35; N, 25.80; S, 11.80.
Dendron 5a: Azide derivative 4a (2.0 g , 8.32 mmol) was allowed to
react with TEA (4.21 mL, 38.23 mmol) and pꢀtouluene
sulfonylchloride (6.35 g, 33.29 mmol) in dry DCM (40 mL)
according to step 3 of persulfonylation . White crystalline product
was isolated; Yield 3.0 g (92%); m.p. 93ꢀ98 °C; IR (νmax/cmꢀ1) 2955.30, 2105.89, 1597.44,
1
1383.48; H NMR (300 MHz, CDCl3) δH 7.93 (d, 4 H, J = 8.4 Hz, Ar-H), 7.36 (d, 4 H, J = 8.1
Hz, Ar-H), 3.81 (t, 2 H, J = 6.6, 6.5 Hz, ꢀCH2), 3.52 (t, 2 H, J = 6.5, 6.9 Hz, ꢀCH2), 2.45 (s, 6 H,

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CH3); 13C NMR (75 MHz, CDCl3) 145.2, 136.3, 129.7, 128.3, 50.3, 46.9, 21.6; Chemical
Formula: C16H18N4O4S2, Elemental Analysis: Calculated; C, 48.72; H, 4.60; N, 14.20; S, 16.26
Found; C, 48.76; H, 4.65; N, 14.22; S, 16.20.
Dendron 5b: Azide derivative 4a (2.0 g, 8.32 mmol) was
allowed to react with TEA (4.21 mL, 33.29 mmol) and pꢀNitro
sulfonylchloride (7.38 g, 33.29 mmol) in dry DCM (20 mL)
according to step 3. Lemon color crystalline product was isolated;
1
Yield 3.5 g (98%); m.p. 110ꢀ117 °C; IR (νmax/cmꢀ1) 2924, 2110, 1528, 1345; H NMR (300
MHz, CDCl3) δH 8.47 (d, 2 H, J = 8.6 HZ, Ar-H), 8.40 (d, 2 H, J = 8.6 HZ, Ar-H), 7.95 (d, 2 H,
J = 8.4 Hz, Ar-H), 7.39 (d, 2 H, J = 8.6 HZ, Ar-H), 3.85 (t, 2 H, J = 6 Hz, -CH2), 3.56 (t, 2 H, J
= 6 Hz, -CH2), 2.48 (s, 3 H, ꢀCH3); 13C NMR (75 MHz, CDCl3) 150.6, 146.0, 135.4, 129.9,
128.5, 124.2, 50.4, 47.4, 21.7; Chemical Formula: C15H15N5O6S2, Elemental Analysis:
Calculated; C, 42.35; H, 3.55; N, 16.46; S, 15.07 Found; C, 42.37; H, 3.51; N, 16.50; S, 15.00.
Dendron 5c: Azide derivative (2.0 g 7.37 mmol) was allowed
to react with TEA (3.7 mL, 29.49 mmol) and pꢀ
Nitrosulfonylchloride (6.6 g, 29.49 mmol) in dry DCM
according to step 3. Yellow solid; Yield 2.5 g, (79%); m.p. 83ꢀ85 °C; IR (νmax/cmꢀ1) 2929, 2117,
1530, 1353; 1H NMR (300 MHz, CDCl3) δH 8.45 (d, 4 H, J = 8.9 Hz, Ar-H), 8.33 (d, 4 H, J = 8.6
13
Hz, Ar-H), 3.94 (t, 2 H, J = 6 Hz, ꢀCH2), 3.62 (t, 2 H, J = 6 Hz, ꢀCH2); C NMR (75 MHz,
CDCl3) 150.9, 144.1, 130.01, 124.4, 50.59, 48.15; Chemical Formula: C14H12N6O8S2,
Elemental Analysis: Calculated; C, 36.84; H, 2.65; N, 18.41; S, 14.05 Found ; C, 36.80; H,
2.60; N, 18.45; S, 14.10.

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Synthesis of dendrimers:
The alkyne terminated core molecules (1.0 eq.) and azide functionalized dendrons (1.1 eq. per
alkyne group) followed by Cu(PPh3)3Br (0.1 mol% per alkyne group) as copper(I) catalyst and
Me6TREN (0.1 mol% per alkyne group) were dissolved in dry DCM and stirred at room
temperature for 8ꢀ10 h. After confirming the completion of reaction by TLC, chloroform was
added to the reaction mixture and washed with saturated solution of NH4Cl in water (10 mL)
followed by brine (10mL). The separated organic layer was dried over Na2SO4 and solvent was
evaporated under reduced pressure to obtain the crude product. The desired products were
obtained after purification by flash column chromatography.
Dendrimer D1: Compound 1a (0.2 g, 0.83 mmol) was reacted with 5a (1.08 g, 2.75 mmol),
Cu(PPh3)3Br (2.12 mg, 2.50 µmol), and Me6TREN (700 µL, 2.62 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D1 was isolated by column chromatography
with hexane/ethyl acetate (3/7). White solid; Yield 1.15 g (98%); IR (νmax/cmꢀ1) 3126, 3039,
2914, 2843, 1180; 1H NMR (300 MHz, CDCl3) δH 7.76 (s, 3 H, Triazol-H) 7.68 (d, 12 H, J = 7.8
Hz, Ar-H), 7.12 (d, 12 H, J = 7.8 Hz, Ar-H) 6.35 (s, 3 H, Ar-H), 5.63 (t, 6 H, J = 7.8 Hz, ꢀCH2),
13
4.78 (s, 6 H, ꢀCH2), 4.21 (t, 6 H, J = 7.2 Hz, ꢀCH2), 2.48 (s, 18 H, ꢀCH3); C NMR (75 MHz,
CDCl3) 158.7, 145.3, 144.1, 135.8, 129.8, 128.2, 122.1, 98.1, 58.1, 49.2, 47.5, 29.2, 27.7, 21.1;
SEC shows polydispersity 1.01; m/z MALDI-TOF MS Calculated; for C61H57N15O21S6
1422.31, Found; 1423.67 [M + H]+.
Dendrimer D2: Compound 1a (0.2 g, 0.83 mmol) was reacted with 5b (1.17 g, 2.75 mmol),
Cu(PPh3)3Br (2.12 mg, 2.50 µmol), and Me6TREN (700 µL, 2.62 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D2 was isolated by column chromatography

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with hexane/ethyl acetate (1/3). Off white solid; Yield 1.2 g (95%); IR (νmax/cmꢀ1) 3130, 3041,
2924, 2853, 1172; 1H NMR (300 MHz, CDCl3) δH 8.34 (d, 6 H, J = 8.1 Hz, Ar-H), 8.06 (d, 2 H,
J = 8.4, Ar-H), 7.80 (d, 6 H, J = 7.7 Hz, Ar-H), 7.79 (s, 3 H, TriazoleꢀH), 7.36 (d, 6 H, J = 7.8
Hz, Ar-H), 6.35 ( s, 3 H, Ar-H), 5.64 (t, 6 H, J = 6.2 Hz, ꢀCH2), 5.08 (s, 6 H, ꢀCH2), 4.31 (t, 6
H, J = 6 Hz, ꢀCH2 ), 2.48 (s, 9 H, ꢀCH3); 13C NMR (75 MHz, CDCl3) 158.1, 150.7, 148.6, 146.1,
144.1, 139.2, 129.9, 126.9, 124.6, 106.2, 86.9, 66.8, 31.9, 29.6, 21.7; SEC shows polydispersity
1.01; m/z MALDI-TOF MS Calculated; for C61H57N15O21S6 1515.22, Found; 1516.68 [M +
H]+.
Dendrimer D3: Compound 1a (0.2 g, 0.83 mmol) was reacted with 5c (1.25 g, 2.75 mmol),
Cu(PPh3)3Br (2.12 mg, 2.50 µmol), and Me6TREN (700 µL, 2.62 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D3 was isolated by silica gel column
chromatography with hexane/ethyl acetate (1/4). Yellow solid; Yield 0.82 g (65%); IR (νmax/cmꢀ
1) 3426., 2924, 2853; 1596, 1480; 1H NMR (CDCl3, 300 MHz) δH 8.40 (d, 12 H, J = 8.1 Hz, Ar-
H) 8.24 (d, 12 H, J = 8.1 Hz, Ar-H), 8.06 (s, 3 H, TriazoleꢀH ), 6.62 (s, 3 H, Ar-H), 5.80 (t, 6 H,
J = 6.6 Hz, ꢀCH2 ), 5.10 (s, 6 H, ꢀCH2), 4.91 (t, 6 H, J = 6.1, ꢀCH2); 13C NMR (CDCl3, 75 MHz)
159.6, 150.7, 146.3, 144.4, 134.9, 130.1, 129.6, 128.4, 124.4, 123.5, 98.6, 59.6, 49.0, 47.8, 29.6;.
SEC shows polydispersity 1.02; m/z MALDI-TOF MS Calculated for C58H50N18O26S6 1608.52,
Found 1609.52 [M + H]+.
Dendrimer D4: Compound 2a (0.2 g, 0.68 mmol) was reacted with 5c (0.90 g, 2.26 mmol),
Cu(PPh3)3Br (1.92 mg, 2.06 µmol), and Me6TREN (550 µL, 2.06 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D4 was isolated by column chromatography
with hexane/ethyl acetate (1/7). Offꢀwhite solid; Yield 1.01g (98%); IR (νmax/cmꢀ1) 2924, 2853,
1
1596, 1480; H NMR (300 MHz, CDCl3) δH 7.76 (d, 12 H, J = 7.8 Hz, Ar-H) 7.54 (s, 3 H,

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Triazole-H), 7.31 (s, 12 H, J = 7.5 Hz, Ar-H), 4.52 (t, 6 H, J = 6.2 Hz, CH2), 4.35 (t, 6 H, J = 6.8
13
Hz, CH2), 4.08 (s, 6 H, CH2), 2.49 (s, 18 H, ꢀCH3); C NMR (75 MHz, CDCl3) 178.7, 145.5,
135.8, 129.8, 128.2, 122.1, 49.2, 47.5, 29.2, 21.6; SEC shows polydispersity 1.03; m/z MALDI-
TOF MS Calculated for C60H63N15O12S9 1473.23, Found 1474.75 [M + H]+.
Dendrimer D5: Compound 2a (0.2 g, 0.686 mmol) was reacted with 5b (0.96 g, 2.26 mmol),
Cu(PPh3)3Br (1.92 mg, 2.06 µmol), and Me6TREN (550 µL, 2.06 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D5 was isolated by column chromatography
with hexane/ethyl acetate (1/4). Light yellow solid; Yield 1.00 g (92%); IR (νmax/cmꢀ1) 3099,
1
2927, 2850, 1533, 1480, 1380, 1166; H NMR(300 MHz, CDCl3) δH 8.35 (d, 6 H, J = 8.1 Hz,
Ar-H) 8.08 (d, 6 H, J =8.4 Hz, Ar-H ), 7.83 (d, 6 H, J = 7.7 Hz, Ar-H), 7.53 (s, 3 H, Triazoleꢀ
H), 7.35 (d, 6 H, Ar-H ) 4.52 (t, 6 H, J = 7.2 Hz, CH2), 4.36 (t, 6 H, J = 7.2 Hz, CH2 ) 4.15 (s, 6
13
H, CH2), 2.47 (s, 9 H, CH3); C NMR (75 MHz, CDCl3,) 178.6, 150.7, 146.3, 144.4, 144.1,
134.9, 130.1, 129.6, 128.4, 124.4, 123.5, 49.0, 47.8, 29.6, 24.9, 21.7; SEC shows polydispersity
1.03; m/z MALDI-TOF MS calculated for C57H54N18O18S9 1566.13, Found 1568.74 [M + H]+.
Dendrimer D6: Compound 2a (0.2 g, 0.68 mmol) was reacted with 5c (1.0 g, 2.26 mmol),
Cu(PPh3)3Br (1.92 mg, 2.06 µmol), and Me6TREN (550 µL, 2.06 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D6 was isolated by column chromatography
hexane/ethyl acetate (1/8). Yellow solid; Yield 0.70 g (62%); IR (νmax/cmꢀ1) 3109, 2914, 2823,
1530, 1482, 1382, 1156; 1H NMR (300 MHz, CDCl3) δH 8.41 (d, 6 H, J = 8.4 Hz, Ar-H) 8.20 (d,
6 H, J = 8.4 Hz, Ar-H), 8.06 (s, 3 H, Triazole-H), 5.09 (t, 6 H, J = 6 Hz, CH2), 4.48 (s, 6 H,
13
CH2), 4.37 (t, 6 H, J =6.2 Hz, CH2); C NMR (75 MHz, CDCl3) 177.7, 155.4, 132.7, 131.1,
129.9, 126.9, 124.5, 54.6, 52.5, 42.7, 33.1; SEC shows polydispersity 1.03; m/z MALDI-TOF
MS calculated for C54H45N21O24S9 1660.04, Found 1660.97 [M + H]+.

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Dendrimer D7: Compound 3a (0.2 g, 0.84 mmol) was reacted with 5a (1.10 g, 2.75 mmol),
Cu(PPh3)3Br (2.35 mg, 2.53 µmol), and Me6TREN (700 µL, 2.62 µmol) Dry DCM (10 mL)
according to the above procedure. Pure compound D7 was isolated by column chromatography
with hexane/ethyl acetate (1/9). Offꢀwhite solid; Yield 1.0 g (83%); IR (νmax/cmꢀ1) 3475, 3068,
2924, 2855, 1452, 1161;1H NMR (300 MHz, CDCl3) δH 7. 85 (d, 12 H, J = 8.4 Hz, Ar-H), 7.73
(s, 3 H, TriazoleꢀH) 7.54 (s, 3 H, -NH), 7.32 (d, 12 H, J = 7.5 Hz, Ar-H), 4.53 (s, 6 H, J = 6.2
Hz, CH2), 4.37 (s, 6 H, CH2), 4.06 (t, 6 H, J = 6 Hz, CH2 ), 2.49 (s, 18 H, CH3); 13C NMR (75
MHz, CDCl3) 165.5, 148.3, 137.1, 129.1, 128.3, 124.8, 47.1, 31.9, 29.3, 21.6; SEC shows
polydispersity 1.01; m/z MALDI-TOF MS calculated for C60H66N18O12S6 1423.67, Found
1423.98 [M + H]+.
Dendrimer D8: Compound 3a (0.2 g, 0.84 mmol) was reacted with 5b (1.10 g, 2.75 mmol),
Cu(PPh3)3Br (2.15 mg, 2.53 µmol), and Me6TREN (700 µL, 2.62 µmol) Dry DCM (10 mL)
according to the above procedure. Pure compound D8 was isolated by silica gel column
chromatography with MeOH/CHCl3 (1/20). Light yellow solid; Yield 1.10 g (87%); IR (νmax/cmꢀ
1
1) 3475, 3065, 2918, 2856, 1524, 1452, 1350, 1161; H NMR(300 MHz, CDCl3) δH 8.44 (d, 6 H,
J = 8.1 Hz, Ar-H), 8.36 (d, 6 H, J = 8.4 Hz, Ar-H), 7.83 (d, 6 H, J = 7.8 Hz, Ar-H) 7.63 (s, 3 H,
Triazole-H), 7.48 (d, 6 H, J = 7.8 Hz , Ar-H), 7.36 (s, 3 H, ꢀNH), 4.52 (t, 6 H, J = 6.8 Hz, ꢀCH2),
4.36 (s, 6H, ꢀCH2), 4.15 (t, 6 H, J = 6.3 Hz, ꢀCH2), 2.47 (s, 9 H, ꢀCH3);13C NMR (75 MHz,
CDCl3) 165.5, 151.7, 149.3, 146.4, 134.9, 130.1, 129.6, 128.4, 124.4, 123.5, 51.7, 50.0, 21.7;
SEC shows polydispersity 1.03; m/z MALDI-TOF MS calculated for C57H58N21O18S6 1515.76,
Found 1516.58 [M + H]+.
Dendrimer D9: Compound 3b (0.2 g, 0.39 mmol) was reacted with 5a (0.50 g, 1.28 mmol)
Cu(PPh3)3Br (1.08 mg, 1.16 µmol), and Me6TREN (310 µL, 1.16 µmol) in Dry DCM (10 mL)

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according to the above procedure. Pure compound D9 was isolated by column chromatography
with hexane/ethyl acetate (3/17). Light brown solid; Yield 0.62 g (95%); IR (νmax/cmꢀ1) 3426,
2924, 2853, 1596, 1480; 1H NMR (300 MHz, CDCl3) δH 8.34 (s, 3 H, Triazole-H), 8.13 (d, 12 H,
J = 10 Hz, ArH), 7.87 (s, 6 H, J = 6.6 Hz, ArH), 7.39 (s, 3 H, NH), 7.37 (d, 18 H, J = 6.6 Hz,
ArH), 5.24 (t, 6 H, J = 6.2 Hz, CH2), 4.65 (s, 6 H, CH2), 4.22 (t, 6 H, J = 6 Hz, CH2), 2.46 (s, 18
H, CH3); 13C NMR (75 MHz, CDCl3) 164.1, 150.1, 148.3, 146.3, 144.3, 142.5, 135.0, 130.1,
129.7, 128.5, 124.5, 114.4, 70.4, 46.6, 36.6, 21.7; SEC shows polydispersity 1.03; m/z MALDI-
TOF MS calculated C78H79N18O15S6 1699.96, Found 1700.04 [M + H]+.
Dendrimer D10: Compound 3b (0.2 g, 0.39 mmol) was reacted with 5b (0.55 g, 1.28 mmol),
Cu(PPh3)3Br (1.08 mg, 1.16 µmol), and Me6TREN (310 µL, 1.16 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D10 was isolated by column chromatography
with hexane/ethyl acetate (1/9); Light brown solid; Yield 1.2 g (96%); IR (νmax/cmꢀ1) 3416, 2914,
2843, 1586, 1560, 1440; 1H NMR (300 MHz, CDCl3) δH 8.32 (d, 9 H, J = 8.7 Hz, ArH), 8.13 (d,
6 H, J = 8.6 Hz, ArH), 7.87 (d,12 H, J = 8.2 Hz, ArH), 7.87 (s, 3 H, Triazole-H), 7.36 (d, 6 H, J
= 7.8 Hz, ArH), 7.39 (s, 3 H, ꢀNH), 7.29 (d, 6 H, J = 7.8 Hz, ArH), 5.22 (t, 6 H, J = 6.2 Hz, ꢀ
13
CH2), 4.67 (s, 6 H, ꢀCH2), 4.24 (t, 6 H, J = 6 Hz, ꢀCH2), 2.46 (s, 18 H, ꢀCH3); C NMR (75
MHz, CDCl3) 164.1, 150.5, 145.2, 142.1, 137.4, 136.1, 129.6, 128.2, 127.8, 126.1, 124.6, 115.2,
48.2, 38.6, 21.7; SEC shows polydispersity 1.03; m/z MALDI-TOF MS Calculated
C75H70N21O21S6, 1791.33 Found 1792.87 [M + H]+.
Dendrimer D11: Compound 3c (0.2 g, 0.30 mmol) was reacted with 5a (0.77g, 1.94 mmol),
Cu(PPh3)3Br (1.64 mg, 1.77 µmol), and Me6TREN (480 µL, 1.80 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D11 was isolated by column chromatography
with hexane/ethyl acetate (1/9). Off white solid; Yield 0.88g, (98%); IR (νmax/cmꢀ1) 3421, 2923,

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2843, 1590, 1478; 1H NMR(500 MHz, CDCl3) δH 8.13 (d, 24 H, J = 8.1 Hz, ArH), 8.13 (d, 24 H,
7.5 Hz, ArH) 7.65 (s, 6 Hꢀ TriazoleꢀH), 7.40 (d, 24 H, J = 7.2 Hz, ArH), 7.39 (s, 6 H, ꢀNH), 7.32
(s, 3 H, ArH), 7.18 (d, 3 H, J = 7.5 Hz, ArH) 4.67 (t, 12 H, J = 6.Hz, ꢀCH2), 4.42 (s, 12 H, ꢀ
CH2), 4.13 (t, 12 H, J = 6.2 Hz, ꢀCH2), 2.46 (s, 36 H, ꢀCH3); 13C NMR (125 MHz, CDCl3) 164.6,
150.0, 145.1, 142.1, 137.4, 136.1, 129.6, 128.2, 127.8, 126.1, 124.6, 119.9, 114.1, 106.0, 76.5,
43.3, 29.7 21.0; SEC shows polydispersity 1.03; m/z MALDI-TOF MS Calculated
C135H138N30O30S12, 3044.20 Found 3045.50 [M + H]+.
Dendrimer D12: Compound 3c (0.2 g, 0.30 mmol) was reacted with 5b (0.83 g, 1.94 mmol),
Cu(PPh3)3Br (1.64 mg, 1.77 µmol), and Me6TREN (480 µL, 1.80 µmol) in Dry DCM (10 mL)
according to the above procedure. Pure compound D12 was isolated by column chromatography
with MeOH/CHCl3 (1/20). Light yellow solid; Yield 0.90 g (94%); IR (νmax/cmꢀ1) 3426, 2924,
1
2853, 1596, 1480; H NMR (500 MHz, CDCl3) δH 8.20 (d, 12 H, J = 8.7 Hz, ArH), 8.13 (d, 12
H, J = 7.4 Hz, ArH ), 8.05 (d, 12 H, J = 7.8 Hz, ArH ), 8.02 (d, 3 H, J = 7.5 Hz, ArH), 7.64 (s, 6
H, ArH) 7.80 (s, 3 H, TriazoleꢀH), 7.39 (d, 12 H, J = 7 Hz, ArH), 7.38 (s, 6 H, ꢀNH), 7.27 (s, 3
H, ArH), 7.16 (d, 3 H, J = 7.5 Hz, ArH), 5.36 (t, 12 H, J = 6. Hz, CH2), 4.48 (s, 12 H, ꢀCH2),
4.27 (t, 12 H, J = 6.2 Hz, ꢀCH2), 2.48 (s, 18 H, ꢀCH3) 13C NMR (125 MHz, CDCl3) 164.8,
152.3,143.8, 140.1, 137.1, 129.2, 128.2, 125.9, 120.5, 119.2, 110.2, 108.7, 108.6, 49.7, 42.3,
40.2, 25.8; SEC shows polydispersity 1.02; m/z MALDI-TOF MS calculated for
C129H120N36O42S12, 3231.33 Found 3232.34 [M + H]+.
ACKNOWLEDGMENT
We acknowledge DST India Grant SR/S1/381 OCꢀ42/2012 for financial support. Department of
Chemistry, Institute of Science of Banaras Hindu University is acknowledged for departmental

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facilities and TIFRꢀMumbai for providing the facility for MALDIꢀTOFꢀMS. We are thankful to
Prof. B. Ray, BHU, for his help in GPC analysis of dendrimers. SKR thanks CSIR, New Delhi,
for SRF.
SUPPORTING INFORMATION
1
Electronic Supplementary Information (ESI) for copies of H and 13C NMR of synthesized
compounds, MALDIꢀTOF of dendrimers, UVꢀspectrum of dendrons and GPC data of
dendrimers.
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An Efficient and Controlled Synthesis of Persulfonylated
G1 Dendrimers Via Click Reaction
Shaziya Khanam,† Sunil K. Rai,† Deepshikha Verma‡, Ranjana S. Khanna† and Ashish K. Tewari†*
†Department of Chemistry (Center of Advanced Study), Institute of Science, Banaras Hindu University, Varanasi-
221005, India.
‡
Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai
400005, India
*Email: tashish2002@yahoo.com
ABSTRACT: A controlled synthesis of clickable dendrimers at room temperature using
aromatic/heteroaromatic cores and persulfonylated dendrons has been performed. Click reactions
went smoothly with Cu(PPh3)3Br complex in the presence of tridentate chelating ligands and
produced copper free G1 dendrimers in excellent yield.