ORIGINAL ARTICLE

Surfactants Based on Bis-Galactobenzimidazolones: Synthesis,Self-Assembly and Ion Sensing Properties

L. Lakhrissi • N. Hassan • B. Lakhrissi •

M. Massoui • E. M. Essassi • J. M. Ruso •

C. Solans • C. Rodriguez- Abreu

Received: 1 December 2010 / Accepted: 22 February 2011 / Published online: 15 March 2011

� AOCS 2011

Abstract A series of new non-ionic amphiphiles based

on bis-galactobenzimidazolones have been synthesized by

grafting alkyl bis-benzimidazolone units as hydrophobic

tails on hydroxypropyloxygalacto-pyranose moieties as

hydrophilic heads. Their surface and self-aggregation

properties in water were evaluated. The compounds show

very low critical micellar concentrations (CMCs) that

decrease with increasing chain length; values for the

minimal area per molecule at the interface (Amin) follow

the same trend. The synthesized compounds also form

hexagonal liquid crystals in water for a certain range of

hydrophobic tail lengths. On the other hand, the new am-

phiphiles show characteristic UV–Vis absorption and

fluorescence emission bands associated with the benzimi-

dazolone moiety. The fluorescence emission is quenched

with a certain degree of selectivity by cations, due to their

strong affinity towards the benzimidazolone group, which

shows ion complexation properties. Hence, the reported

new amphiphiles are candidates as self-assembling

chemosensors. The quenching efficiency and also ion

sensing sensitivity is higher in the monomeric state as

compared to the micellar state. The fluorescence emission

intensity is higher for compounds with a shorter alkyl

chain.

Keywords Bis-benzimidazolones � D-Galactose �Surfactant synthesis � Non-ionic surfactants � Surface

properties � Fluorescence probe spectroscopy

Introduction

Sugar-based surfactants, with their low toxicity and

excellent biodegradability, i.e. reduced environmental

impact, offer an attractive alternative to more conventional

non-ionic surfactants such as poly(ethyleneoxide) alkyl

ethers[1]. Moreover, they show performance properties

which are exploited in microbiology and biotechnology

[2–4], and have potential pharmaceutical and biomedical

applications [5–7]. Sugar surfactants are made from

renewable resources and are increasingly used in washing

agents [8], cosmetics [9, 10], and drug carriers [11, 12].

The influence of structural changes on the physical prop-

erties of this family of surfactants has been studied in

several reports [1, 13–15].

Electronic supplementary material The online version of thisarticle (doi:10.1007/s11743-011-1262-7) contains supplementarymaterial, which is available to authorized users.

L. Lakhrissi � B. Lakhrissi

Laboratoire d’Agroressources et Genie des Procedes,

Faculte des Sciences, Universite Ibn Tofaıl,

Kenitra, Morocco

L. Lakhrissi � M. Massoui � E. M. Essassi

Laboratoire de Chimie Heterocyclique,

Faculte des Sciences, Universite Mohamed V,

Rabat, Morocco

N. Hassan � J. M. Ruso

Soft Matter and Molecular Biophysics Group,

Department of Applied Physics, University of Santiago de

Compostela, 15782 Santiago de Compostela, Spain

C. Solans � C. Rodriguez- Abreu

Institut de Quımica Avancada de Catalunya (IQAC),

Consejo Superior de Investigaciones Cientıficas (CSIC),

Jordi Girona, 18-26, 08034 Barcelona, Spain

C. Rodriguez- Abreu (&)

International Iberian Nanotechnology Laboratory,

Av. Mestre Jose Veiga, 4715-310 Braga, Portugal

e-mail: crodriguez@inl.int

123

J Surfact Deterg (2011) 14:487–495

DOI 10.1007/s11743-011-1262-7

On the other hand, benzimidazolones are important

heterocyclic components of various products with phar-

maceutical and biological importance [16–19]. They also

present chelating and complexation properties [20], and

show a characteristic UV absorption band and fluorescence

emission [21, 22]. Hence, they can act as intrinsic

chemosensor molecules in which the donor atoms for

substrate complexation are a part of the fluorophore [23,

24]; the interaction between the bound substrate and the

fluorophore leads directly to the modification of its emis-

sion properties. However, the low solubility in water is

a drawback, therefore designing benzimidazolone-based

hydrosoluble chemosensors is an interesting goal [25].

They could attract an additional interest if they would have

amphiphilic nature and therefore form self assemblies in

solution or on substrates [23].

In a continuation of our previous work in this area

[26–29], we have synthesized a series of new non-ionic

amphiphiles based on bis-galactobenzimidazolone (see

Fig. 1a), which was prepared by grafting the 6-O-[2,3-ep-

oxypropyl]-1,2:3,4-di-O-isopropylidene-a–galactopyranose

group on the N-3 nitrogen atom of two benzimidazolone

units that are linked by an alkyloxypropylene group in the

same conditions as described earlier [29], following by

the deprotection of diacetonide galactopyranose moiety

[28–31]. The new synthesis route is easier and involves

fewer steps than the previously reported one [29].

Additionally, we evaluated surface and self-aggregation

properties in water by several techniques such as surface

tension, fluorescent probe spectroscopy, and polarized

optical microscopy. The ion complexing properties of the

synthesized compounds were studied by UV–Vis and

fluorescence spectroscopy.

Experimental

Chemical Analysis

Thin-layer chromatography (TLC) was performed on Silica

Gel 60 F254 (E. Merck) plates with visualization by UV

light (254 nm) and/or charring with the vanillin–H2SO4

reagent. Column chromatography was performed using

230–400 mesh E Merck silica gel. Melting points were

determined on an automatic electrothermal IA 9200 digital

melting point apparatus in capillary tubes and are uncor-

rected. Optical rotations, for solutions in chloroform or

methanol, were measured with a digital polarimeter JAS-

CO model DIP-370, using a sodium lamp at 25 �C.1H-NMR spectra were recorded on a Bruker 300 WB

spectrometer at 300 MHz, and 13C-NMR spectra were

recorded at 75 MHz for solutions in CDCl3 or Me2SO-d6.

Chemical shifts are given as d values with reference to

tetramethylsilane (TMS) as internal standard. Analytical

TLC was performed on Merck aluminium backed silica

gel (Silica Gel F254); spots were visualized in UV light.

Column chromatography was performed on silica gel

(60 mesh, Matrix) by elution with hexane–acetone or

acetone–methanol mixtures.

Synthesis

All chemicals were purchased from Aldrich or Acros

(France). All solvents were distilled before use. The

compound N,N0-1,3-Bis-[N-3-(6-deoxy-3-O-methyl-D-glu-

copyranose-6-yl)-2-oxo-benzimidazole-1-yl)]-2-dodecyloxy

propane, abbreviated as LBC12, was synthesized as reported

in a previous paper [29].

Fig. 1 Structures of

(I) N,N0-1,3-bis-[N-3-(6-

(20-hydroxypropyloxy)-

D-galactopyranos-6-yl)-

2-oxobenzimidazol-1-yl)]-

2-alkyloxypropanes (4a-c) and

(II) N,N- 1,3-Bis-[N-3-

(6-deoxy-3-O-methyl-D-

glucopyranos-6-yl)-2-

oxobenzimidazol-1-yl)]-

2-dodecyloxypropane

(compound LBC12)

488 J Surfact Deterg (2011) 14:487–495

123

1,3-N,N0-bis-[2-oxobenzimidazol-1-yl]-2-alkyloxypro-

panes 1a-c were synthesized in three steps. The first one is

the condensation of N-isopropenylbenzimidazolone [20]

with epichlorohydrin in a toluene-DMSO mixture in the

presence of potassium carbonate. The second step is the

alkylation of the free OH group by n-bromoalkanes in a

toluene-DMSO mixture and potassium hydroxide [29].

Subsequent N-3 deprotection in a cold acid medium [20]

afforded the corresponding compounds 1a–c.

6-O-[2,3-epoxypropyl]-1,2:3,4-di-O-isopropylidene-a-

D-galactopyranose 2 was synthesized by adopting the

modified Koll’s method [32] which consists of the reaction

of 1,2:3,4-di-O-isopropylidene-a-D-galactopyranose [33]

with epichlorohydrin in the presence of sodium hydroxide

and in Toluene-DMSO mixture as solvent.

N,N0-1,3-Bis-[N-3-(6-(20-hydroxypropyloxy)-1,2:3,4-di-

O-isopropylidene-a-D-galactopyranos-6-yl)-2-oxobenzimid

azol-1-yl)]-2-alkyloxypropanes 3a–c were synthesized

following Scheme 1, by condensing the 1,3-N,N0-bis-[2-

oxobenzimidazol-1-yl]-2-alkyloxypropanes 1a–c [29] units

with activate galactopyranose 2 in the presence of potas-

sium carbonate and in pure DMSO as solvent [28, 29].

In order to give a hydrophilic character to the molecules

obtained 3a–c, they were treated with a mixture of triflu-

oroacetic acid–water (9:1, v/v) at room temperature

[29–31]. The precipitates obtained were purified by chro-

matography with a mixture of acetone-methanol (1:1, v/v)

to give N,N0-1,3-bis-[N-3-(6-(20-hydroxypropyloxy)-D-ga-

lactopyranos-6-yl)-2-oxobenzimidazol-1-yl)]-2-alkyloxy-

propanes 4a–c as white solids.

Physical constants are given in Tables 1 and 2 as a

function of n, which is the number of carbon atoms in the

n-alkyl chain.

Surface and Self-Aggregation Properties

The surface tension of surfactant solutions was measured

by the Wilhelmy plate method with a Kruss K12

tensiometer at 25 �C. The samples were left to rest for

several hours to reach equilibrium. Consecutive measure-

ments were performed until surface tension data was con-

stant with time. From the graphical plots of surface tension

against logarithm of surfactant concentration the values of

critical micelle concentration (CMC) were obtained.

UV–Vis and Fluorescence Spectroscopy

UV–Vis spectra at 25 �C were measured using a Varian

Cary UV–Visible spectrophotometer whereas steady state

fluorescence was measured at 25 �C using a Varian Cary

Eclipse spectrophotometer. Both instruments were equip-

ped with a temperature-controlled sample holder. Samples

were placed in 1-cm path length quartz cuvettes. Pyrene

was excited at a wavelength of 335 nm and the emission

Scheme 1 Synthesis method

Table 1 Physicochemical constants of compounds 4a–c and their

precursors 3a–c

Product Yield

(%)

Mp ( �C) Molecular

formula½a�26

D ðc ¼ 1:0Þ a/b

Molecular

weight

3a (n = 10) 88.0 68–70 C57H84N4O17 -60.2�a –

1097.29

3b (n = 12) 84.4 62–64 C59H88N4O17 -60.3�a –

1125.35

3c (n = 14) 79.1 58–60 C61H92N4O17 -59.6�a –

1153.40

4a (n = 10) 90.1 120–122 C51H76N4O17 20.4�b 3/4

1017.16

4b (n = 12) 88.0 116–118 C53H80N4O17 20.2�b 5/6

1045.22

4c (n = 14) 86.1 96–98 C55H84N4O17 20.8�b 3/4

1073.27

a In CHCl3b In CH3OH

J Surfact Deterg (2011) 14:487–495 489

123

intensity from 350 to 600 nm was recorded. On the other

hand, fluorescence emission spectra of synthesized com-

pounds (without pyrene) were collected using an excitation

wavelength of 280 nm.

Aqueous solutions of copper, magnesium and sodium

nitrate were used during spectrophotometric titrations. For

experiments with copper nitrate, the pH remained between

5.2 and 6 in the experiments.

Microscopy

Samples placed in glass slides were observed at 25 �C

under a polarized light microscope (Leica Reichert Polyvar

2) equipped with a hot stage (Mettler FP82HT) and a CCD

camera.

Results and Discussion

Surface and Self-Aggregation Properties

The synthesized bis-galactobenzimidazolones 4a–c are

soluble in water. The plot of surface tension versus loga-

rithm of surfactant concentration of compound 4b (alkyl

chain length n = 12) is presented in Fig. 2. Plots corre-

sponding to compounds 4a and 4c (n = 10 and n = 14,

respectively) showed the same features, with clear breaks

in the data trends (see supplementary information, Fig. S1),

which is a typical behavior for surfactants and evidences

their capacity to decrease the surface tension as well as to

form micellar aggregates in aqueous media. The Critical

Micellar Concentrations (CMC) values derived from those

breaks are very low and the surface tension values at the

CMC, namely, the effectiveness of surface tension reduc-

tion, are around, 40 mN/m (see Table 3).

As in the case of other amphiphiles [34], experimental

points for CMC follow approximately an equation of the

form log CMC = a - b�n; a and b be are constants and n is

the alkyl chain length. For the present series of compounds,

Table 2 NMR spectroscopic data of compounds 3a in CDCl3 and 4a in DMSO-d6

Compound Galactosyl moiety Oxo-benzimidazolyl Alkyl chain Propyloxy moiety Hydroxypropyl moiety moiety moiety

3a (n = 10) H1: 5.45 (d, 2H, J1,2 = 5.00) Harom : 7.00-7.28 CH3ω : 0.87(t, 3H) OCH: 4.10 (m ,1H) OCH2: 3.44 (m,2H)

H2: 4.32 (dd, 2H, J2,3 = 2.40) (m, 8H) CH2ω−1 : 1.03(sext, 2H) NCH2: 3.95 (m, 4H) CHOH: 4.25 (m,2H)

H3: 4.60 (dd, 2H, J3,4 = 8.00) 7CH2 : 1.05-1.55(m,14H) NCH2: 3.95(dd, 1H) H4: 4.24 (dd, 2H, J4,5 = 1.70) OCH2

α : 3.35 (t, 2H) J1,2 = 5.5 4.30 (dd, 1H) H5: 3.96 (m, 2H, J5,6a = 6.60) H6a : 3.68 (dd, 4H, J6,6 = 10.10) Jω,ω−1 = 7.2 H6b: 3.54(dd, 4H, J5,6b = 4.20) Jα,β = 6.4 CH3iso: 1.24 -1.46 (4s, 12H) OH: 2.12 (s, 2H)

3a (n = 10) C1: 96.2 C2=O: 155.1 CH3ω: 14.1 NCH2: 43.6 OCH2: 72.3;72.5

C2: 70.4 C4,C7:108.4;108.5; CH2ω−1: 22.6 OCH: 76.5 CHOH: 69.0;69.2

C3: 70.6 108.6;109.3 5CH2 : 29.3-31.8 NCH2: 44.3;44.4 C4: 71.1 C5,C6:121.3;121.5 CH2

γ : 25.7 C5: 66.7;66.7 C8,C9:129.5;129.8 CH2

β : 29.6C6: 71.4 ΟCH2

α : 71.3 (CH3)2: 26.2;26.5

Ciso: 111.7 4a (n = 10) C1α : 92.7 C2α=O: 153.8 CH3

ω: 13.9 NCH2: 43.1 OCH2: 72.8;72.9 C1β: 97.4 C2β=O: 153.9 CH2

ω−1: 22.1 OCH: 76.1 CHOH:69.2;69;3 C2, C3, C4, C5 : 68.4 − 83.1 C4,C7:108.2;108.5 5CH2: 28.6 - 31.2 NCH2: 44.3;44.4 C-6 : 70.1 C5,C6:120.6;120.8 CH2

γ : 25.0 C8,C9:129.4;129.5 CH2

β: 29.2 129.7;129.8 ΟCH2

α : 70.8

Fig. 2 Surface tension (squares) and ratio of intensities of first and

third peaks in pyrene fluorescence spectrum (I1/I3, circles) as a

function of surfactant concentration (25 �C) for compound 4b(n = 12). The lines serve to indicate the break for each set of data

490 J Surfact Deterg (2011) 14:487–495

123

b (&0.06) is quite small when compared to other surfac-

tants [34], indicating that the effect of increasing the

hydrophobic chain length on the aggregation tendency is

less marked.

The surface excess concentration (Cmax) corresponding

to the maximum concentration of surfactant adsorbed at

the saturated liquid/air interface, in mol/cm2, is obtained

from the Gibbs equation for non-ionic surfactants, Cmax =

-(dc/dlnC)/(RT), where (dc/dlnC) is the slope of the sub-

micellar region of the plot of surface tension against loga-

rithm of surfactant concentration, R = 8.31 J.mol-1. K-1

and T is the temperature in K. From the surface excess

values, the area occupied per molecule of surfactant

adsorbed at the air/liquid interface (Amin), expressed in A2,

is obtained according to Amin = 1016/NA Cmax where NA is

the Avogadro’s number and Cmax is the surface excess

concentration.

The Cmax and Amin values obtained (Table 3) are of the

same order as those of alcohol ethoxylates with an average

number of ethylene oxide units of 6–8 [34, 35], and very

close to LBC12 homologue series (see Fig. 1) with alkyl

chain lengths in the range n = 10–14 [29]. The values of

effective surface area per molecule at the interface (Amin)

follow the typical decreasing trend with increasing hydro-

phobic tail length.

Pyrene is a fluorescent probe sensitive to the polarity of

the microenvironment, which is proportional to the ratio of

the first and third peaks in the probe emission spectrum

(I1/I3). As a result, it has been widely used for the deter-

mination of the CMC. Figure 2 shows the results on

fluorescence probe spectroscopy for compound 4b (alkyl

chain length n = 12). Plots corresponding to compounds

4a and 4c (n = 10 and n = 14, respectively) exhibited the

same features (see supplementary information, Fig. S2),

with clear breaks signalling a change in the microenvi-

ronment surrounding pyrene at the onset of aggregate

formation. As can be seen in Table 3, the values of CMC

derived from the breaks in I1/I3 data are in agreement with

those derived from surface tension measurements.

Amphiphilic compounds usually form lyotropic liquid

crystals in water. The small amount of surfactant available

from the synthesis reported here made it difficult to prepare

well mixed, concentrated samples in water with a precise

surfactant concentration. In such a case it is common to use

the water penetration method to detect qualitatively the

liquid crystal formation. Samples of the compounds 4a–c

were examined by means of polarized optical microscopy.

As it can be seen in Fig. 3, when putting the synthesized

compounds in contact with water, they form liquid crystals

with hexagonal grainy optical texture for alkyl chain lengths

of 10 and 12 carbons. For 14 carbons, clear liquid crystal

optical textures could not be observed; birefringence seems

to be produced by crystals of insoluble solid. The compound

LBC12, with a similar structure, also forms hexagonal

liquid crystals in water, as reported in a previous article [29].

Ion Complexation

We tried first to characterize the ion complexation

properties of the synthesized compounds by UV–Vis

Table 3 Physicochemical parameters of compounds 4a–c

Product Chain

length, nCMC from surface

tension (mM)

CMC from

fluorescence (mM)

cCMC

(mN/m)

Cmax 9 1010

(mol/cm2)

Amin (A2)

4a 10 0.0025 0.0024 38 2.7 (3 and 2.3) 60 (55 and 70)

4b 12 0.0016 0.0016 44 2.9 (3.2 and 2.5) 57 (52 and 66)

4c 14 0.0014 0.0013 41 3.4 (3.7 and 3.4) 48 (45 and 48)

Values of Cmax and Amin for alcohol ethoxylates with an average number of ethylene oxide units of 6 and 8 and the same alkyl chain length of

compounds 4a–c are shown between brackets and in italics (data taken from Refs. [34, 35])

Fig. 3 Images of optical polarized microscopy (25 �C) for compounds 4a–c (a) n = 10 (b) n = 12 (c) n = 14. The compounds were put in

contact with water (black region in the image) for the observation

J Surfact Deterg (2011) 14:487–495 491

123

spectrometry. UV spectra can be found in the supplemen-

tary information (Figs. S3 and S4). In the absence of Cu2?,

the spectra of 4b and LBC12 compounds show a single

absorption band with a maximum at 282 nm; compounds

4a and 4c show the same spectral features. The position of

the characteristic band is almost the same as that of

benzimidazolone in organic polar solvents such as ethanol

and acetonitrile [21]. Upon addition of Cu2?, Mg2? or

Na?, a slight bathochromic (red) shift was observed for the

282 nm band, and a new (overlapped) band seems to

develop; from deconvolution of the spectra, the maximum

of this band is estimated to be around 300–302 nm, almost

in the same position of that found for neat cation (nitrate)

solutions. The band remained even after subtraction of

cation background, but results are not conclusive con-

cerning the effect of ion complexation on UV–Vis spectra,

particularly because the 302 nm band could not be

detected at cation concentrations within the same order of

magnitude of that of the synthesized compounds in the

experiments.

Fluorescence spectroscopy is known to be an analysis

technique much more sensitive than UV–Vis spectrometry.

Fluorescence emission spectra of compounds 4b upon

titration with Cu2? are shown in Fig. 4. Neat 4a–c aqueous

solutions (0.005 mM) show a single emission band at

312 nm, similar to benzimidazolone in organic polar sol-

vents such as ethanol and acetonitrile [21]; this spectral

feature is not changed by Cu2? addition, but the fluores-

cence intensity at the maximum decreases, i.e. there is a

cation-induced quenching. Cation affinity of the imidazole

group is determined by its complexing properties. The

quenching process is induced by coordination of cations

either directly to donor atoms of the fluorophore or to

chelating groups covalently attached to the latter [36].

Particularly, Cu2? has a high thermodynamic affinity for

typical N,O-chelate ligands and fast metal-to-ligand bind-

ing kinetics [37].

As can be observed in Fig. 5, fluorescence intensity

quenching follows the Stern–Volmer relationship [38, 39],

Io/I = 1 ? KSV [Q], where Io and I are the fluorescence

intensities in the absence and in the presence of quencher,

respectively, [Q] is the quencher concentration and KSV is

the Stern–Volmer quenching constant (other Stern–Volmer

plots can be found in the supplementary information,

Figs. S5 and S6); K is a measure of the quenching effi-

ciency. Results points to a diffusion-controlled quenching

process. KSV values for 4b and LBC12 (both with the same

alkyl chain length) decrease in the order Mg2?[Cu2?[Na?

(see Table 4). Ionic radii of Mg2? and Cu2? are very similar

and both are lower than that of Na?, hence, the relationship

between ionic radius and KSV is not straightforward. KSV

values for Cu2? as quencher are higher for LBC12 when

compared to 4b, the latter having a bulkier group sur-

rounding the benzimidazolone moiety. Therefore, steric

effects might be playing a role. It should be mentioned here

that other cations, such as Ca2? and Pb2? were also found to

induce fluorescence quenching of the compound 4b.

Concerning the effect of amphiphile concentration, KSV

for Cu2? increases from 0.1532 to 1.0141 mM-1 when 4b

concentration is decreased from 0.005 mM (micellar state)

280 300 320 340 360 380 400

I(A

.U.)

Wavelength (nm)

0 mM

6 mM

Fig. 4 Fluorescence spectra (25 �C) for different Cu2? concentra-

tions in aqueous solutions of compound 4b. The surfactant concen-

tration is kept at 0.005 mM. Cu2? concentrations are varied from 0 to

6 mM in 1 mM steps

Fig. 5 Stern-Volmer plot for surfactants LBC12 and 4b (both with

the same alkyl chain length) with Cu2? as quencher (25 �C). Io and

I are the fluorescence intensities in the absence and in the presence of

quencher, respectively. The surfactant concentration is fixed at

0.005 mM. The position of fluorescence maxima remains constant

at 312 nm

Table 4 Values for of Stern–Volmer constants (KSV) in mM-1 for

different cations as quenchers (25 �C)

Surfactant Mg2? Cu2? Na?

4b 0.1922 0.1532 0.1098

LBC12 0.3106 0.2762 0.2510

The surfactant concentration is fixed at 0.005 mM

492 J Surfact Deterg (2011) 14:487–495

123

to 0.0005 mM (monomer state); hence, the quenching

efficiency and also ion sensitivity is improved at low am-

phiphile concentration. This tendency has been reported

before for associating polymers [40], and was attributed not

only to stoichiometry but also to aggregation-related

effects [40].

On the other hand, the alkyl chain length has practically

no effect on KSV for Cu2? as quencher. Nevertheless, there

are differences in the fluorescence intensity as a function of

4a–c concentration in neat solutions (no cation added): the

shorter the alkyl chain, the stronger the emission intensity.

This effect was found for certain alkyl substituted fluoro-

phores [41], and was attributed to changes in chain confor-

mation that affect fluorescent properties. The fluorescence

intensity in the absence of cations (see supplementary

information, Fig. S7) increased linearly with concentration

of compounds 4a–c with no apparent discontinuity or step-

like fluorescence enhancement in the vicinity of the CMC,

contrary to that observed for another fluorescent amphiphile

[42]. The position of the fluorescence intensity maximum

also remained invariable below and above the CMC. This

fact might be attributed to the location of the fluorescent

moiety near the hydrophilic group, which remains highly

solvated below and above the CMC, namely, the slight

change in microenvironment, if any, cannot be detected by

fluorimetry.

Conclusions

The synthesized bis-galactobenzimidazolones are soluble

in water and form micellar aggregates at very low con-

centration. Their surface properties are similar to some

ethoxylated nonionic surfactants. The synthesized com-

pounds are also capable of forming lyotropic liquid crystals

within a certain range of alkyl chain lengths. Moreover,

they show UV–Vis absorption and fluorescence emission

properties; the latter can be used for ion sensing as the

fluorescence is quenched by cations that form complexes

with the benzimidazolone moiety. Hence, the reported new

amphiphiles are promising as self-assembling chemosen-

sors. The quenching efficiency is higher in the monomer

state as compared to the micellar state. It was also found

that the emission intensity increased with decreasing alkyl

chain length.

Acknowledgments This work was supported by CNRST-CSIC

project (2007MA0055). The ‘‘Ministere Marocain de l’Enseignement

Superieur’’ is gratefully acknowledged. C.R-A is also grateful to the

Ministerio de Ciencia e Innovacion, Spain (Project CTQ2008-01979/

BQU) for research funding. J.M.R and N. H. thank Direccion Xeral de

Promocion Cientıfica e Tecnologica del sistema Universitario de

Galicia for their financial support.

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Author Biographies

L. Lakhrissi studied chemistry at the Mohamed V University of

Rabat (Morocco) and then at the Ibn Tofaıl University of Kenitra

(Morocco). She is now a Ph.D. candidate in organic synthesis and

surfactant properties, at the Mohamed V University of Rabat

(Morocco).

N. Hassan studied chemistry at the University of Chile (Santiago-

Chile) and she is currently a Ph.D. candidate in Science and

Technology of Materials at the University of Santiago de Compostela

(Spain).

B. Lakhrissi studied chemistry at the Henri Poincare University of

Nancy (France) and obtained his Ph.D. in organic and analytic

chemistry from the same University in 1988. Since 1989 he has been

an assistant professor at the Ibn Tofaıl University in Kenitra

(Morocco). He obtained his state doctorate thesis in organic chemistry

from Ibn Tofaıl University of Kenitra (Morocco) in 2003 and since

then he has been a professor at that university. Since 2005 he has also

been Director of the Agro resources and Process Engineering

Laboratory. His areas of scientific activity are organic synthesis,

surfactant properties and complexant systems.

M. Massoui studied chemistry at the Picardie University of Amiens

(France) and received his doctorate in Organic Chemistry from the

same University in 1985. Since then he has been Professor at Ibn

Tofaıl University in Kenitra (Morocco). He was also Director of the

Agro resources and Process Engineering Laboratory. His area of

scientific activity is the organic synthesis and the chemistry of

glucids.

E. M. Essassi studied chemistry at the Mohamed V University of

Rabat (Morocco) and received his doctorate in Organic Chemistry

from the University of Montpellier (France) in 1977. He then joined

the University Mohammed V in Rabat and was promoted to Professor

in 1981. Professor Essassi is currently Director of the Heterocyclic

Organic Chemistry Laboratory. In 2006 he was named a member of

Hassan II Academy of Science and Technology. His area of scientific

activity is organic synthesis.

J. M. Ruso is an associate professor at the University of Santiago de

Compostela. He received his Ph.D. (1998) from the University of

Santiago de Compostela. He was a visiting researcher at the

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123

University of Manchester, Columbia University and Universidad

Nacional del Sur. His research focuses on design and characterization

of mesoporous materials, nanotechnology, self assembled supramo-

lecular structures and physicochemical characterization of proteins

and protein aggregates.

C. Solans is a researcher at the Institute for Advanced Chemistry of

Catalonia of the Spanish Council for Scientific Research (CSIC) in

Barcelona, Spain. She received a B.Sc. degree in Chemistry (1970)

from the University of Barcelona (Spain) an M.Sc. degree in

Chemistry (1980) from the University of Missouri-Rolla (U.S.A.)

and a Ph.D. in Chemistry (1983) from the University of Sevilla

(Spain). Her current research interests include surfactant phase

behavior and their application to emulsification processes by low-

energy methods, detergency, solubilization and synthesis of materials.

C. Rodriguez-Abreu received his B.Sc. and M.Sc. in Chemical

Engineering from the University of Los Andes (Venezuela) and

obtained his Ph.D. in engineering from the Yokohama National

University (Japan) in 2001. After working as an associate professor at

the University of Los Andes (Venezuela) and as a research fellow at

Yokohama National University (Japan), University of Santiago de

Compostela (Spain), and the Institute for Advanced Chemistry of

Catalonia (IQAC)-Spanish Council of Scientific Research (CSIC), he

joined the International Iberian Nanotechnology Laboratory in 2010.

His area of scientific activity is the physical-chemistry of amphiphilic

systems, and their application in the synthesis of nanomaterials.

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