The Real Structure of Formamide Entrapped by AOT Non Aqueous Reverse Micelles: FT-IR and 1HNMR Studies *
N. Mariano Correaa, , Paulo Augusto R. Pires b, Juana J. Silbera and Omar A. El Seoudb,* a
Departamento de Química. Universidad Nacional de Río Cuarto. Agencia Postal # 3. C.P. 5800 Río Cuarto. ARGENTINA; bInstituto de Química. Universidade de São Paulo. C.P. 26.077. 05513-970 São Paulo. S.P., Brazil, and* Corresponding author. E-mail:
[email protected];
[email protected] 1
Table1S. Regression Analysis Results for the Dependence on [Solubilizate]/[AOT] of the IR Stretching Frequencies and 1H NMR Chemical Shifts.(a) Parameter System Equation(b) A B C D c.c. (c) (d) FA-W/S Expon/1 2516.45 60.079 5.11 0.9969 νOD Area(e) FA-W/S Linear 0 11.94 0.9994 FA/S Polynom/2 4060.81 -36.149 8.97 0.9979 (f) δ CHC
δNHA
(f)
FA/S
Polynom/2
3550.39
92.61
δNH
(f)
FA/S
Linear
3491.25
11.54
0.9994
(g)
FA/S
Linear
2190.41
-60.68
0.9984
(g)
FA/S
Linear
1596.96
-7.34
0.9991
(g)
FA/S
Polynom/2
2067.4
-12.09
2.38
(h)
FA-W/S
Polynom/2
4074.67
-10.58
1.52
δNHA
( (h)
FA-W/S
Expon/1
3706.03
-180.96
2.83
0.9989
δNH
(h)
FA-W/S
Expon/1
3610.80
-134.41
17.96
0.9991
(h)
FA-W/S
Polynom/2
1843.96
62.79
-4.88
(h)
FA-W/S
Polynom/2
2188.52
-14.94
0.76
0.9980
(h)
FA-W/S
Expon/1
1560.49
40.95
4.88
0.9974
δ δ δ
δ δ
0.9916
B
1
H
1'
H
H
0.9989
3'
δ CHC
δ
-23.06
-0.078
0.9981
B
0.16
0.9998
OH 1
H
1'
H
(a)Abbreviations: FA = Formamide; S = AOT, and W = water. (b)- Equations which gave the best regression analyses, followed by its order; eg., for FA/S, polynom/2 means the following second-order polynomial equation: δNHC = A + B ([Solubilizate]/[S]) + C ([Solubilizate]/[S])2. For FA-W/S, expn/1 refers to the following firstorder exponential decay: νOD = A + B exp(-[FA-W/S]/C). Exponential= Exponential decay of the type: Parameter = Polynomial = Polynomial equation of the type: Parameter = + D ([Solubilizate]/[S])3 + E ([Solubilizate]/[S])4 (c) Regression correlation coefficient. (d)νOD = Stretching frequency of the O-D band of aqueous FA. Regression analyses were carried out for [solubilizate]/[AOT] from 2.12 to 13.04. (e)Area of the main peak of the O-D band obtained by curve fitting, e.g., Figure 7B. 1
HNMR chemical shift of the HC ( δ CHC ), HA ( δNHA ) and HB ( δNH ) group of FA B (see Scheme 1 for the nomenclature). Regression analyses were carried out for [solubilizate]/[S] from 0.45 to 2.05. 2 (f)
(g) δH1, δH1’, δH3 refer to the 1H NMR chemical shift of the H1, H1' and H3 of the surfactant, respectively. Regression analyses were carried out for [solubilizate]/[AOT] from 0.45 to 2.05. (h) δOH refers to the 1HNMR chemical shift of the OH group of solubilized water in FA-W. The rest symbols have the same definition given in (f) and (g) but for FA-W. Regression analyses were carried out for [solubilizate]/[AOT] from 0.58 to 9.62.
3
1SA 0.4
Absorbance
0.3
0.2
0.1
0.0 2200
2300
2400
2500
2600
2700
2800
-1
Wavenumber (cm )
180
1SB
160
Area (arbitray Units)
140 120 100 80 60 40 20 0
0
2
4
6
8
[FADH-HOD]/[AOT]
4
10
12
14
50
1SC
45 40 35
∆ν OD
30 25 20 15 10 5 0
2
4
6
8
10
12
14
[Solubilizate]/[AOT]
Figure 1S. (A) Representative band deconvolution of the νOD peak of FADH - HOD solubilizate in AOT/n-heptane reverse micelles. [FADH-HOD]/[AOT] = 6.19. The solid-line peak is experimental, whereas the symbols ( ), ( ) and ( ), are used to denote the two peaks calculated by curve fitting and their sum, respectively. (B). Dependence of the area of the main νOD peak on [FADH-HOD]/[AOT]. (C) Dependence of ∆νOD = νOD at any [solubilizate]/[AOT] - νOD at [solubilizate]/[AOT] of 13.0) on [solubilizate]/[AOT]: z (FADH-HOD), (HOD).
5
