PCCP
Paper
ꢀ
ꢀ
between 0.2 and 30 mM do not contain exchangeable Br / OH
counterions because in this case a change in kobs should be
observed. This means that within this concentration range
the micelles are exclusively formed by SC6HM and C TAB. Above
3 F. M. Menger, L. Shi and S. A. A. Rizvi, J. Am. Chem. Soc.,
2009, 131, 10380–10381.
4 F. M. Menger and S. A. A. Rizvi, Langmuir, 2011, 27, 13975–13977.
5 F. A. Garc ´ı a Daza and A. D. Mackie, J. Phys. Chem. Lett., 2014,
5, 2027–2032.
12
3
0 mM the kobs values display a sharp increase, reach a maximum
value and drop again. Further, for high concentrations of C12TAB the
kinetic data attain the values obtained in the absence of SC6HM.
This behavior is typical of cationic micelles with exchangeable
counterions and indicates that the mixed micelles are gradually
transformed into ‘‘quasi like’’ micelles as the concentration of
SC6HM becomes more diluted within the aggregates.
6 Y. Kang, K. Liu and X. Zhang, Langmuir, 2014, 30, 5989–6001.
7 X. Zhang and C. Wang, Chem. Soc. Rev., 2011, 40, 94–101.
8 C. Wang, Z. Wang and X. Zhang, Acc. Chem. Res., 2012, 45,
608–618.
9 N. Basilio, M. Mart ´ı n-Pastor and L. Garc ´ı a-R ´ı o, Langmuir,
2012, 28, 6561–6568.
1
1
1
0 N. Basilio, V. Francisco and L. Garcia-Rio, Int. J. Mol. Sci.,
2013, 14, 3140–3157.
Conclusions
1 V. Francisco, N. Bas ´ı lio, L. Garcia-Rio, J. R. Leis, E. F. Marques
and C. V ´a zquez-V ´a zquez, Chem. Commun., 2010, 46, 6551–6553.
2 N. Basilio, B. G o´ mez, L. Garcia-Rio and V. Francisco, Chem.
Eur. J., 2013, 19, 4570–4576.
This work demonstrates that supra-amphiphiles formed from
SC6HM and C12TAB aggregate into micellar aggregates with
tunable degrees of ionization. For low C12TAB : SC6HM molar
ratios the micelles are negatively charged. As the concentration
of C12TAB increases the negative micellar charge decreases and
reaches neutrality at C12TAB : SC6HM E 6. Above this point the
micelles become positively charged and their ability to solubilize
more C TAB decreases substantially. As a result the fraction of
1
3 N. Basilio and L. Garc ´ı a-R ´ı o, Chem. – Eur. J., 2009, 15, 9315–9319.
14 D.-S. Guo and Y. Liu, Acc. Chem. Res., 2014, 47, 1925–1934.
15 B.-P. Jiang, D.-S. Guo, Y.-C. Liu, K.-P. Wang and Y. Liu, ACS
Nano, 2014, 8, 1609–1618.
1
1
1
1
2
2
6 Z. Qin, D.-S. Guo, X.-N. Gao and Y. Liu, Soft Matter, 2014, 10,
1
2
2
253–2263.
7 K. Wang, D.-S. Guo, M.-Y. Zhao and Y. Liu, Chem. – Eur. J.,
014, DOI: 10.1002/chem.201303963.
8 Y. Cao, Y. Wang, D. Guo and Y. Liu, Sci. China Chem., 2013,
7, 371–378.
9 D.-S. Guo, B.-P. Jiang, X. Wang and Y. Liu, Org. Biomol.
Chem., 2012, 10, 720–723.
0 D.-S. Guo, K. Wang, Y.-X. Wang and Y. Liu, J. Am. Chem. Soc.,
free C TAB also increases until it reaches a new critical
1
2
concentration leading to a second aggregation process.
2
The kinetics of the MBSC hydrolysis and NPV basic hydrolysis
show that C12TAB : SC6HM micelles have the ability to solubilize
hydrophobic compounds within their structure. This result together
with their reduced CMC demonstrate the higher potential of
C TAB : SC6HM based supra-amphiphiles compared with conven-
5
12
tional surfactants. The basic hydrolysis of NPV was shown to be a
very effective probe to investigate the ionic composition of the
micellar interface in this complex system. The results suggest that
2012, 134, 10244–10250.
1 Z. Li, C. Hu, Y. Cheng, H. Xu, X. Cao, X. Song, H. Zhang and
Y. Liu, Sci. China Chem., 2012, 55, 2063–2068.
ꢀ
Br anions do not participate in the micelles formed between the
2
2
2 K. Wang, D. Guo and Y. Liu, Chem. – Eur. J., 2012, 18, 8758–8764.
3 K. Wang, D.-S. Guo, X. Wang and Y. Liu, ACS Nano, 2011, 5,
first and second CMCs. Above this last point, the micellized
C12TAB : SC6HM ratio increases significantly and the counteranions
2
880–2894.
4 K. Wang, D.-S. Guo and Y. Liu, Chem. – Eur. J., 2010, 16,
006–8011.
are transferred into the micellar interface screening the electrostatic
repulsion between positively charged C TAB molecules.
2
2
12
8
5 V. Wintgens, C. Le Coeur, C. Amiel, J.-M. Guigner, J. G.
Acknowledgements
Harangoz o´ , Z. Miskolczy and L. Bicz ´o k, Langmuir, 2013, 29,
7682–7688.
N.B. acknowledges the Fundaç ˜a opara a Ci ˆe ncia e Tecnologia
FCT, Portugal) for a postdoctoral grant (SFRH/BPD/84805/
012). We are grateful to INCT-Cat ´a lise/ CNPq, PRONEX,
2
2
2
6 G. Gattuso, A. Notti, A. Pappalardo, S. Pappalardo, M. F. Parisi
and F. Puntoriero, Tetrahedron Lett., 2013, 54, 188–191.
7 C. A. Bunton, F. Nome, F. H. Quina and L. S. Romsted, Acc.
Chem. Res., 1991, 24, 357–364.
(
2
FAPESC, CSF/CNPq and CAPES for their support of this work.
We acknowledge the financial support from the Ministerio de
Economia y Competitividad of Spain (project CTQ2014-55208-P)
and Xunta de Galicia (2007/085).
8 Y. Geng, L. S. Romsted and F. Menger, J. Am. Chem. Soc.,
2006, 128, 492–501.
2
3
9 L. S. Romsted, Langmuir, 2007, 23, 414–424.
0 M. Cepeda, R. Davi n˜ a, L. Garc ´ı a-R ´ı o, M. Paraj o´ , P. Rodr ´ı guez-
Dafonte and M. Pess ˆe go, Org. Biomol. Chem., 2013, 11, 1093–1102.
1 J. P. Priebe, F. D. Souza, M. Silva, D. W. Tondo, J. M. Priebe,
G. A. Micke, A. C. O. Costa, C. A. Bunton, F. H. Quina,
H. D. Fiedler and F. Nome, Langmuir, 2012, 28, 1758–1764.
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6384 | Phys. Chem. Chem. Phys., 2015, 17, 26378--26385
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