Visible Light Assisted Photocatalytic [3 + 2] Azide−Alkyne “Click” Reaction for the Synthesis of 1,4-Substituted 1,2,3-Triazoles Using a Novel Bimetallic Ru−Mn Complex

Visible Light Assisted Photocatalytic [3 + 2] Azide−Alkyne “Click”
Reaction for the Synthesis of 1,4-Substituted 1,2,3-Triazoles Using a
Novel Bimetallic Ru−Mn Complex
Pawan Kumar,†
Chetan Joshi,†
Ambrish K. Srivastava,‡
Piyush Gupta,§
Rabah Boukherroub,∥
and Suman L. Jain*,†
†
Chemical Sciences Division, CSIR-Indian Institute of Petroleum, Mohkampur, Dehradun 248005 India
‡
Department of Physics, University of Lucknow, University Road, Lucknow, Uttar Pradesh 226007, India
§
Anaytical Sciences Division, CSIR-Indian Institute of Petroleum, Mohkampur, Dehradun 248005 India
∥
Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS8520, Lille1 University, Avenue
Poincaré-BP60069, 59652 Villeneuve d’Ascq, France
*S Supporting Information
ABSTRACT: A photoactive bimetallic complex comprising a photo-
sensitizer ruthenium unit and a catalytic Mn(I) unit connected via a
bipyrimidine (bpm) bridging ligand is prepared and used for the first
time for developing a light induced copper catalyzed [3 + 2] azide−
alkyne “click” (CuAAC) reaction for the formation of 1,2,3-triazoles
under visible light irradiation. The developed bimetallic complex
exhibited enhanced activity as both the photosensitizer ruthenium unit
as well as manganese catalyst unit are attached in a single molecule,
providing efficient electron transfer for the photochemical reduction of
Cu(II) to Cu(I) in situ which subsequently was used for the
cycloaddition of azides with terminal alkynes to give 1,4-disubstituted
1,2,3-triazoles in the presence of triethylamine as a sacrificial donor.
KEYWORDS: Photocatalyst, Click reaction, Ruthenium, Manganese, Visible light, Redox catalyst, Triazoles
■ INTRODUCTION
Development of sustainable chemical synthesis in order to
diminish the detrimental environmental impact associated with
chemical industries is a prime objective in present day
chemistry. Sunlight, being an abundant, safe, and easily available
energy resource, holds great potential in driving environ-
mentally benign organic transformations.1
Importantly, light
induced reactions provide room temperature chemical syn-
thesis, and also avoid thermally induced side reactions.
However, simple organic molecules mainly absorb only
ultraviolet (UV) light, which is only 5% of the solar spectrum
and requires special vessels for reactions. Owing to these
limitations, development of visible light assisted photocatalytic
reactions is receiving particular interest in current decades.2,3
In
this regard, a plethora of selective organic transformations on a
semiconductor photocatalyst have been developed, which can
be performed in common glass reactors.4,5
However, lower
efficiency and poor product yields are the common drawbacks
of such catalytic systems. Transition metal complexes such as
ruthenium or iridium metal complexes and metal free organic
dyes have also been acknowledged as excellent homogeneous
photocatalysts for a series of organic transformations under
visible light irradiation.6,7
The copper catalyzed azide−alkyne
cycloaddition (CuAAC) also known as a “click reaction” is a
well-accepted, widely utilized, reliable, and straightforward
approach to transform organic azides and terminal alkynes into
the corresponding 1,4-disubstituted 1,2,3-triazoles.8
Owing to
the unique features of the CuAAC reaction, such as high
efficiency, high yields, and mild reaction conditions, this has
been established to be a powerful tool in organic synthesis,
medicinal chemistry, polymer chemistry, and surface mod-
ifications.9,10
Furthermore, the products of CuAAC reactions,
such as 1,4-disubstituted 1,2,3-triazoles, have been employed as
ligands for catalysts and as building blocks for luminescent
metal complexes. In this context, Bai et al. have recently
reported the use of CuAAC reactions in the syntheses of
nitrogen containing ligands such as pyridine, pyrazole, and
benzyltriazole hybridized 1,2,3-triazole ligands and their
application to support luminescent Cu(I) and Zn(II) clusters
and polymeric complexes.11,12
The click reaction is generally
carried out by using a catalytic mixture containing Cu(II) with a
reducing agent (usually sodium ascorbate). The direct use of
Cu(I)/metallic copper or its clusters is also possible; however,
the formation of undesirable alkyne−alkyne homocoupling
Received: July 15, 2015
Revised: September 16, 2015
Published: December 2, 2015
Research Article
pubs.acs.org/journal/ascecg
© 2015 American Chemical Society 69 DOI: 10.1021/acssuschemeng.5b00653
ACS Sustainable Chem. Eng. 2016, 4, 69−75
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products makes such methods of limited synthetic utility. To
overcome these limitations Bai et al. reported a number of
hybrid nitrogen−sulfur ligand supported Cu(I)/(II) complexes
as effective catalysts for azide−alkyne cycloaddition reac-
tion.13,14
Recently, photochemical CuAAC reactions using UV light
have emerged to be a promising approach for various
applications in material synthesis.15,16
In this context, Bowman
and Yagci reported a photoinduced CuAAC reaction using a
Cu(II)/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDE-
TA) complex and a photoinitiator as catalyst under UV
irradiation.17−19
Subsequently, Guan et al. developed a Cu(II)/
carboxylate complex for photoinduced CuAAC reaction under
UV light irradiation.20
However, to the best of our knowledge
there is no report on the visible light assisted photocatalytic
azide−alkyne “click” reaction.
In continuation of our recent research on visible light assisted
photocatalytic transformations,21,22
herein we report the first
successful example of visible light assisted photocatalytic [3 +
2] azide−alkyne “click” reaction using ruthenium−manganese
(Ru−Mn) bimetallic complex as photocatalyst to give 1,4-
substituted 1,2,3-triazoles in the presence of Cu(II) sulfate and
triethyl amine (Figure 1 and Scheme 1). The developed
bimetallic complex was found to be more efficient as both
photosensitizer (Ru unit) and photocatalyst (Mn unit) units are
associated within the same molecule, which provides efficient
electron transfer and therefore enhanced catalytic efficiency.
Furthermore, Ru−Mn complex plays a major role and provides
photoinduced in situ reduction of Cu(II) to Cu(I) for the
CuAAC reaction.
■ RESULTS AND DISCUSSION
At first, the Mn(bpm)(CO)3Br complex was synthesized by
following the literature procedure.23
Subsequently, the Ru−Mn
bimetallic ([Ru(bpy)2(bpm)Mn(CO)3Br](PF6)2) complex was
synthesized by the reaction of Ru(bpy)2Cl2 and Mn(bpm)-
(CO)3Br followed by precipitating the product with
ammonium hexafluorophosphate (Scheme 2).24
As shown,
the bipyrimidine ligand provides a coordination site for the
attachment of Ru(bpy)2Cl2 to Mn(bpm)(CO)3Br.25,26
The successful synthesis of bimetallic complex 4 was
confirmed with various techniques like MALDI-TOF-MS,
FTIR, UV−vis, 1
H NMR, 13
C NMR, and elemental analysis.
The detailed characterization of the bimetallic Ru−Mn catalyst
4 is given in the Supporting Information. Figure 2 shows UV−
vis spectra of Mn(bpm)(CO)3Br 2, Ru(bpy)3Cl2 photo-
sensitizer, and Ru−Mn catalyst 4 in DMF. The UV−vis
spectrum of 2 displayed a weak absorption band at 276 nm due
to bpm interligand transition, while a very weak shoulder at 429
nm due to Mn(dπ) → bpm(π*) transition was also observed
(Figure 2a).27,28
The UV−vis spectrum of Ru(bpy)3Cl2
photosensitizer gave a strong absorption band at 285 nm due
to interligand (π → π*) transition and a shoulder at 455 nm
due to MLCT(dπ → π*) transition (Figure 2b).29,30
In the
Figure 1. Photoredox catalyst [Ru(bpy)2(bpm)Mn(CO)3Br](PF6)2
(Ru−Mn complex).
Scheme 1. Photocatalytic “Click” Reaction between Organic
Azides and Terminal Alkynes for the Synthesis of 1,4-
Substituted 1,2,3-Triazoles
Scheme 2. Synthesis of [Ru(bpy)2(bpm)Mn(CO)3Br](PF6)2
(Ru−Mn Complex 4)
Figure 2. UV−vis absorption spectra of (a) Mn(bpm)(CO)3Br 2, (b)
Ru(bpy)3Cl2, and (c) Ru−Mn complex 4.
ACS Sustainable Chemistry & Engineering Research Article
DOI: 10.1021/acssuschemeng.5b00653
70

Table 1. Photocatalytic “Click” Reaction of Azides and Alkynes by Using Ru−Mn Complex 4a
a
Reaction conditions: alkyne (1 mmol), azide (1.5 mmol), copper(II) sulfate (0.5 mmol), TEA (0.5 mL), catalyst (5 mol %), ethanol (10 mL).
Visible light (20 W LED, λ > 400 nm). b
Isolated yield of the product.
71

Ru−Mn complex the attachment of the ruthenium unit to the
manganese unit through coordination with bipyrimidine ligand
exhibited a significant enhancement in the absorbance (Figure
2c). The peak at 286 nm in the UV−vis spectrum of the Ru−
Mn complex was due to a bipyridine interligand (π−π*)
transition, while the broad hump at 420 nm was due to the
Ru(dπ) → bpy(π*) transition.
The synthesized bimetallic Ru−Mn complex was used for the
copper catalyzed [3 + 2] azide−alkyne cycloaddition “click”
reaction of terminal alkynes with azides to give 1,4-substituted
1,2,3-triazoles under visible light irradiation using triethylamine
as a sacrificial donor and 20 W white cold LED light as a source
of visible light. In the present study, copper(II) sulfate was used
and underwent in situ photochemical reduction to give Cu(I)
catalytic species. A variety of alkynes and azides were
investigated, and in all cases higher conversions and yields of
the corresponding 1,4-substituted 1,2,3-triazoles were obtained
in 5−7 h of irradiation period (Table 1). The obtained 1,4-
disubstituted 1,2,3-triazoles were easily isolated by extraction
with ethyl acetate, followed by recrystallization, and identified
by comparing their physical and spectral data with those of
authentic samples. Among the various alkynes, aromatic alkynes
gave higher yields (Table 1, entry 1−14). Among the various
aromatic alkynes, electron withdrawing groups such as −Br,
−Cl containing substrates exhibited higher activity which is
most likely due to the easy formation of intermediate copper
acetylide during the reaction.31
In the case of various
substituted azides, those having electron donating groups
(methyl) were found to be somewhat sluggish toward the
“click” chemistry as compared to the azides containing electron
withdrawing groups (−Cl).
Further, to establish the superiority of bimetallic Ru−Mn
photocatalyst 4, we have checked various possible combinations
of catalyst fragments for the photoinduced “click” reaction
between alkynes and azides. Phenyl acetylene and benzyl azide
were chosen as model substrates for this study. Blank reaction
without any catalyst did not give any reaction product even
after prolonged time of exposure to visible light (Table 2, entry
1). Moreover, the use of Mn(CO)5Br, Mn(bpm)(CO)3Br,
Ru(bpy)2Cl2, or Ru(bpy)3Cl2 as catalyst also did not produce
any reaction product even after 24 h of visible light irradiation
(Table 2, entry 2−5). After that, a combination of photo-
sensitizer Ru(bpy)3Cl2 and catalyst Mn(bpm)(CO)3Br was
tried, which afforded only 46% yield of the desired product
after 24 h irradiation period. However, the use of bimetallic
(Ru−Mn) complex 4 under identical experimental conditions
provided almost quantitative yield of the desired product within
5 h of irradiation period. These studies suggested that both
photosensitizer ruthenium and catalyst Mn(I) are essential for
this reaction, and attachment of both units in one molecule
(Ru−Mn bimetallic complex 4) through a bridging ligand
enhanced the reaction rate significantly in comparison to the
physical mixing of both units separately. This enhancement in
bimetallic complex may be attributed due to efficient electron
transfer by Ru photosensitizer unit to Mn catalyst unit without
time delay.32,33
To prove the essential role of visible light, we
performed the blank experiment, and no reaction was observed
in the absence of light even after 12 h (Table 2, entry 7).
Furthermore, the presence of Cu(II) sulfate and sacrificial
donor triethylamine was found to be vital, which was confirmed
by performing the reaction in the absence of copper(II) sulfate
and triethyl amine, respectively. No reaction occurred in the
absence of these components (Table 2, entry 6−7). On the
basis of these experiments, it was concluded that bimetallic
Ru−Mn complex, Cu(II) sulfate, triethyl amine, and visible
light all were essentially required for this transformation.
Furthermore, to establish the effect of photocatalyst, controlled
experiments using copper(II) sulfate and Cu(II) sulfate with
triethyl amine in the absence of photocatalyst under otherwise
identical experimental conditions were performed (Table 2,
entry 8). In both cases, no conversion was observed, suggesting
that the presence of Ru−Mn photocatalyst 4 was essential to
promote the CuAAC reaction under visible light irradiation.
The effect of solvent on light induced “click” reaction was
studied in detail by varying the different solvents for the “click”
reaction between phenyl acetylene and benzyl azide under the
described reaction conditions. The results of these experiments
are summarized in Table 3. As shown the reaction was found to
be sluggish in highly polar solvents such as DMF, DMSO, etc.
The yield % (TOF) of product in various solvents, i.e., DMF,
DMSO, THF, and water, was determined to be 52% (10.4),
76% (15.2), 87% (15.8), and 89% (17.8), respectively.
Table 2. “Click” Reaction Using Various Catalyst Combinations under Different Experimental Conditionsa
entry catalyst time (h) yieldb
TOF (h−1
)
1 24
2 Mn(CO)5Br 24
3 Mn(bpm)(CO)3Br 24
4 Ru(bpy)2Cl2 24
5 Ru(bpy)3Cl2 24
6 Ru(bpy)3Cl2 + Mn(bpm)(CO)3Br 24 46 1.9
16 c
12 d
12 e
7 Ru−Mn complex 4 5 96 19.2
16 4c
0.25
10 6d
0.6
8 14e
1.7
8 CuSO4 24
CuSO4 + TEA 24
a
Reaction conditions: phenyl acetylene (1 mmol), benzyl azide (1.5 mmol), Cu(II) sulfate (0.5 mmol), TEA (0.5 mL), catalyst (5 mol %), ethanol
(10 mL), visible light (20 W LED λ > 400 nm); room temperature (25 °C). b
Isolated yield. c
In the absence of light. d
Without CuSO4. e
In the
absence of TEA.
72

Furthermore, the % yield (TOF) of the product in methanol
(MeOH), acetonitrile (ACN), and dichloromethane (DCM)
was found to be 78% (15.6), 64% (6.4), and 48% (6.0),
respectively. Ethanol was the best solvent for the photoinduced
“click” reaction with 96% (19.2) yield of triazoles (Table 3,
entry 4). It can be concluded from Table 3 that solvents with
moderate polarity were optimal for this reaction.
In order to explain the photocatalytic “click” reaction, a
plausible reaction mechanism is proposed as depicted in
Scheme 3. After absorption of visible light, the ruthenium
sensitizer unit of photocatalyst is excited, and the electrons
move from its HOMO to LUMO. The excited ruthenium unit
transfers electrons to the Mn catalyst unit through the
bipyrimidine bridging ligand.34
After that, one electron reduced
(OER) Mn catalyst unit transfers electron to Cu(II), which is
subsequently reduced in situ to give Cu(I) catalytic species for
the “click” reaction.35
In contrast to the existing literature
reports, in the present work, no reducing agent like sodium
ascorbate for reducing Cu(II) to Cu(I) is required. Triethyl-
amine acts as a sacrificial donor and provides the necessary
electrons for this process.36,37
The increase in catalytic activity
of the catalyst was assumed to be due to the fast electron
transfer from the Ru unit to the Mn unit because of attachment
of both units through the bipyrimidine bridging ligand.
ν− + → *−Ru Mn h Ru Mn
* − → −+ −
Ru Mn Ru Mn
− + → + −+ − +
Ru Mn Cu(II) Cu(I) Ru Mn
− + → − ++ •• •+
Ru Mn (C H ) N Ru Mn (C H ) N2 5 3 2 5 3
+ ≡ +
→ = = +
 
   
Cu(I) R C CH R N
R (C CH N N N) R Cu(II)
3
■ CONCLUSION
In conclusion, we have demonstrated the first successful visible
light induced copper catalyzed [3 + 2] cycloaddition (CuAAC)
“click” reaction between azides and terminal alkynes to give 1,4-
disubstituted 1,2,3-triazoles in high yields using a novel
bimetallic Ru−Mn complex as photocatalyst. In the synthesized
photocatalyst, the ruthenium photosensitizer unit is attached to
manganese carbonyl complex by bipyrimidine bridging ligand,
which provided rapid electron transfer without delay in contact
time and resulted in enhanced reaction rate in comparison to
the physical mixing of photosensitizer and Mn complex in the
reaction mixture. Furthermore, copper(II) sulfate has been used
for the CuAAC reaction which is converted in situ to active
Cu(I) catalytic species through photochemical reduction
without need of reducing agent like sodium ascorbate. To the
best of our knowledge this is the first report on the visible light
induced CuAAC “click” reaction which can be further used for
various applications including applications in material science as
well as surface functionalization.
■ EXPERIMENTAL SECTION
Materials. 2,2′-Bipyridine (99%), 2,2′-bipyrimidine (95%), and
ruthenium chloride trihydrate were purchased from Sigma-Aldrich and
used without further purification. Mn(CO)5Br (98%), ammonium
hexafluorophosphate (99.9%), dimethylformamide (DMF, HPLC
grade), and acetonitrile (HPLC grade) were of analytical grade and
procured from Alfa Aesar. All other chemicals were of A.R. grade and
used without further purification.
Characterization Techniques. Absorption spectra in the UV−vis
region of Mn(bpm)(CO)3Br and Ru−Mn complex were collected in
DMF on PerkinElmer lambda-19 UV−vis−NIR spectrophotometer
using a 10 mm quartz cell, with BaSO4 as reference. Fourier transform
infrared (FTIR) spectra were recorded on Perkin−Elmer spectrum
RX-1 IR spectrophotometer using potassium bromide window. 1
H
NMR and 13
C NMR spectra of metal complexes were taken at 500
MHz by using a Bruker Avance-II 500 MHz instrument. MALDI-
TOF-MS analysis for confirming the synthesis of the Ru−Mn complex
was conducted on Thermo Exactive Orbitrap system in HESI mode.
Ru and Mn metal contents of Mn(bpm)(CO)3Br and Ru−Mn
complex were determined with ICP-AES analysis by inductively
coupled plasma atomic emission spectrometer (ICP-AES, DRE, PS-
3000UV, Leeman Laboratories Inc.). Samples for ICP AES analysis
were prepared by oxidizing 50 mg of catalyst by HNO3 and heating at
70 °C for 15 min. The final volume was made up to 5 mL by adding
deionized water. Elemental contents of (bpm)(CO)3Br and Ru−Mn
complex were determined on CHN analyzer (Vario micro cube
elementar). Photoirradiation was carried out under visible light by
using 20 W white cold LED flood light (model no. HP-FL-20W-F-
Hope LED Opto-Electric Co., Ltd.). Intensity of the light at vessel was
measured by intensity meter and was found to be 75 W m−2
.
Synthesis of Mn(bpm)(CO)3Br. The Mn complex was synthe-
sized by following a literature procedure.23
Briefly, a mixture of 2, 2′-
bipyrimidine (120.2 mg, 0.76 mmol) and Mn(CO)5Br (199.6 mg, 0.72
mmol) was refluxed in 40 mL of diethyl ether for 3 h in the dark. The
obtained orange Mn(bpm)(CO)3Br was collected by filtration, washed
with diethyl ether, and dried in vacuum. Yield: 185.1 mg (68.4%). 1
H
NMR spectrum (500 MHz, DMSO-d6) was in accordance with
literature values (Figure S1). UV−vis: λmax = 276 nm(s), 429 nm(w),
Table 3. Effect of Solvent on Photoinduced “Click”
Reactiona
entry solvent time (h) yieldb
TOF (h−1
)
1 DMF 5.0 52 10.4
2 DMSO 5.0 76 15.2
3 water 5.5 87 15.8
4 THF 5.0 89 17.8
5 EtOH 5.0 96 19.2
6 MeOH 5.0 78 15.6
7 CH3CN 10.0 64 6.4
8 CH2Cl2 8.0 48 6.0
a
Reaction conditions: phenyl acetylene (1 mmol), benzyl azide (1.5
mmol), Cu(II) sulfate (0.5 mmol), TEA (0.5 mL), catalyst 4 (5 mol
%), solvent (10 mL), visible light (20 W LED λ > 400 nm), room
temperature (25 °C). b
Isolated yield.
Scheme 3. Plausible Mechanism of Visible Light Induced
“Click” Reaction by Ru−Mn Complex
73

FT-IR: ν(CO)/cm−1
, 2028, 1943, 1922 (Figure S2). Elemental
analysis, C11H6BrMnN4O3, Calcd (Found): C%, 35.04 (35.34); H%,
1.60 (1.58); N%, 14.86 (14.73). Mn% by ICP-AES, 14.57 (14.38).
Synthesis of Ru−Mn Complex [Ru(bpy)2(bpm)Mn(CO)3Br]-
(PF6)2. A mixture of Ru(bpy)2Cl2·2H2O38
(130.05 mg, 0.25 mmol)
and Mn(bpm)(CO)3Br (93.98 mg, 0.25 mmol) was refluxed in 15 mL
of ethanol for 12 h under nitrogen atmosphere. After cooling to room
temperature, the reaction mixture was filtered through membrane
filter. The filtrate was dried under vacuum by rotary evaporation to
getting crude catalyst. The purification of the catalyst was carried out
by dissolution of the material in a minimum amount of ethanol
followed by reprecipitation with diethyl ether. This process was
repeated three times. Yield: 107.43 mg (54.4%). The product was
identified by MALDI-TOF-MS: [M+
] − 2CO (1023.9), [M+
] − 3CO
(995.9), [M+
] − Br − F − H (979.0), [M+
] − Br − CO − F − 3H
(949.3), [M+
] − PF6 (935.0), [M+
] − PF6 − Br (856.9), [M+
] − PF6
− 3CO (851.2), [M+
] − PF6 − Br − CO (825.9), [M+
] − 2PF6 − CO
− F + 3H (745.1), [M+
] − 2PF6 − 3CO (705.2), [M+
] − 2PF6 −
Mn(CO)3Br (572.1) (Figures S3−S5). UV−vis: λmax = 286 nm (s)
and 420 nm (s). Elemental analysis, C31H22BrMnN8O3RuP2F12, Calcd
(Found): C%, 34.44 (35.08); H%, 2.03 (1.97); N%, 10.37 (10.24). Mn
% by ICP-AES, 5.08 (4.97); Ru% by ICP-AES, 9.35 (9.22). 1
H NMR
(500 MHz, DMSO-d6): δ = 7.00−8.10 (m, 5H), 8.10−8.50 (m, 1H),
9.15−9.45 (m, 2H), 9.45−9.80 (m, 3H). 13
C NMR (500 MHz,
DMSO-d6): δ = 124.09, 138.00, 160.16, 161.58 (Figures S6 and S7).
FT-IR v(CO)/cm−1
: 2030, 1995, 1924 (Figure S8).
Typical Experimental Procedure for Visible Light Promoted
“Click” Reaction. To a round-bottom flask containing 10 mL of
ethanol, alkyne (1 mmol), azide (1.5 mmol), Cu(II)sulfate (0.5
mmol), and triethylamine (0.5 mL) was added catalyst 4 (5 mol %).
The flask was sealed with a septum and irradiated with stirring by
using a 20 W white cold LED (model HP-FL-20W-F-Hope LED
Opto-Electric Co., Ltd.) for a desired time period. After completion of
the reaction, monitored by TLC, the reaction mixture was filtered, and
the product was extracted using DCM and washed with water and
brine. The material was dried over Na2SO4. The solvent was removed
under vacuum, and the product having some catalyst was isolated. The
product was purified by dissolution of the material in a minimum
amount of DCM, followed by addition of hexane to precipitate the
catalyst, filtration, and drying under vacuum. Further purification was
performed by using column chromatography on silica gel. The product
was identified with FTIR, 1
H NMR, and 13
C NMR.
■ ASSOCIATED CONTENT
*S Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acssusche-
meng.5b00653.
Characterization data of synthesized catalysts (MALDI-
TOF, 1
H NMR, 13
C NMR, FTIR, etc.) and analysis of
reaction products (FTIR, 1
H NMR, 13
C NMR) (PDF)
■ AUTHOR INFORMATION
Corresponding Author
*E-mail: suman@iip.res.in. Phone: 91-135-2525788. Fax: 91-
135-2660202.
Notes
The authors declare no competing financial interest.
■ ACKNOWLEDGMENTS
The authors would like to thank the Director of IIP for granting
permission to publish these findings. The analytical department
is acknowledged for its kind support in analysis of samples. P.K.
is also thankful to CSIR for providing fellowships to conduct
research. C.J. is thankful to CSIR, New Delhi, for funding in
CSC-0117 12th five year projects.
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Visible Light Assisted Photocatalytic [3 + 2] Azide−Alkyne “Click” Reaction for the Synthesis of 1,4-Substituted 1,2,3-Triazoles Using a Novel Bimetallic Ru−Mn Complex

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