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ChemComm
catalytic activity in Sonogashira cross coupling reactions and in
photocatalytic degradation of RhB dye.
M.K. and V.B. are thankful to DST (ref. no. SR/S1/OC-69/2012)
and CSIR (ref. no. 02(0083)/12/EMR-II), respectively, for financial
Fig. 3 (A) Sonogashira–Hagihara coupling of phenyl acetylene with aryl support. We are also thankful to UGC (New Delhi) for ‘‘University
2 3 2 3
iodides catalyzed by ferromagnetic a-Fe O nanoparticles. (B) a-Fe O
nanoparticles (i) dispersed in the reaction mixture; (ii) adsorbed on a
magnetic stirring bar; (iii) an external magnet attracted stirring bar and
with Potential for Excellence’’ (UPE) project. S.P. is thankful to
UGC (New Delhi) for Senior Research Fellowship (SRF).
2 3
a-Fe O nanoparticles.
Notes and references
1
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was monitored by observing the change in the intensity of the
characteristic absorption peak of RhB at 555 nm (Fig. S21A,
ESI†). The absorption spectrum of RhB solution showed a time-
1
2007, 19, 33; (e) C. T. Black, C. B. Murray, R. L. Sandstrom and S. Sun,
dependent change in the presence of a-Fe O3 nanoparticles
2
Science, 2000, 290, 1131; ( f ) R. F. Ziolo, E. P. Giannelis, B. A. Weinstein,
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(2 mM) under visible-light irradiation. The characteristic absorp-
tion peak of RhB at 555 nm rapidly decreased in intensity as time
prolonged and it disappeared completely after about 26 minutes
and the color of the solution changed from the initial pink-red to
almost colourless (Fig. S21A, ESI†). The rate constant for photo-
(h) M. Lewin, N. Carlesso, C. H. Tung, X. W. Tang, D. Cory,
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2 3
catalytic degradation of aqueous RhB dye by a-Fe O was found
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À3 À1
to be 1.79 Â 10
s
(Fig. S21B, ESI†).
2
In addition, we also carried out Sonogashira cross coupling
of aryl-iodides (4a–b) and phenyl acetylene in the presence of
these nanoparticles to yield the desired products in high yields
within 24 hours as shown in Fig. 3A (Table S9, ESI†). The products
3
4
5 Y. Li and W. Shen, Chem. Soc. Rev., 2014, 43, 1543.
6 (a) V. Bhalla, A. Gupta and M. Kumar, Chem. Commun., 2012,
1
13
(
5a–b) were isolated and characterized by H NMR, C NMR and
48, 11862; (b) K. S. nee Kamaldeep, S. Kaur, V. Bhalla, M. Kumar
ESI-MS (Fig. S22–S25, ESI†). The catalytic efficiency of these a-Fe
2 3
O
and A. Gupta, J. Mater. Chem. A, 2014, 2, 8369.
nanoparticles is comparable/better than the existing Pd-based cata-
lysts for the mentioned Sonogashira coupling reactions (Table S10a
7 (a) V. Bhalla, S. Pramanik and M. Kumar, Chem. Commun., 2013,
4
9, 895; (b) Y. Hong, J. W. Y. Lam and B. Z. Tang, Chem. Soc. Rev.,
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2
3
8 (a) Y. Kubota, S. Tanaka, K. Funabiki and M. Matsui, Org. Lett., 2012,
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easily separated from the reaction mixture by a magnet and the
separated catalysts could be recycled 5 times without signifi-
cant loss in its activity (Fig. 3B). The separation and reuse of the
9
J. Lian, X. Duan, J. Ma, P. Peng, T. Kim and W. Zheng, ACS Nano,
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2
ferromagnetic a-Fe
and economical. The desired product was not obtained in the
absence a-Fe O nanoparticles.
2 3
2
O
3
nanoparticles was very simple, effective 10 (a) M. Diab and T. Mokari, Inorg. Chem., 2014, 53, 2304; (b) S. Li,
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1
1
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In conclusion, we designed and synthesized hexaphenylbenzene
derivative 3 having azaindole groups which forms fluorescent
aggregates in aqueous media. These aggregates show high affinity
1
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3+
towards Fe ions in the nanomolar range. Interestingly, these 14 S. Yu and G. M. Chow, J. Mater. Chem., 2004, 14, 2781.
1
5 S. Yang, Y. Xu, Y. Sun, G. Zhang and D. Gao, CrystEngComm, 2012,
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aggregates of 3 serve as a reactor and a stabilizer for the preparation
of ferromagnetic a-Fe nanoparticles at room temperature within
0 minutes. Furthermore, these a-Fe nanorods show excellent
1
2 3
O
1
6 G. Liu, Q. Deng, H. Wang, D. H. L. Ng, M. Kong, W. Caia and
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3
2
O
3
1
3536 | Chem. Commun., 2014, 50, 13533--13536
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