Surface interaction and self-assembly of cyclodextrins with organic dyes

Article abstract of DOI:10.1007/s10847-009-9712-9

The interaction of seven novel substituted merocyanine dyes, i.e. 1-methyl-4-[2-(3-methoxy-4-hydroxyphenyl)ethenyl)]pyridinium iodide, 1-methyl-4-[2-(3,5-dimethoxy-4-hydroxyphenyl)ethenyl)]pyridinium iodide, 1-methyl-4-[2-(4-dimethylaminophenyl)ethenyl)]p

Full text of DOI:10.1007/s10847-009-9712-9

J Incl Phenom Macrocycl Chem (2010) 67:317–324
DOI 10.1007/s10847-009-9712-9
ORIGINAL ARTICLE
Surface interaction and self-assembly of cyclodextrins
with organic dyes
•
Bojidarka Ivanova Rositca Nikolova
•
•
Marc Lamshoft Penka Tsanova Ivan Petkov
•
•
¨
Petko Ivanov Michael Spiteller
•
Received: 2 September 2009 / Accepted: 18 November 2009 / Published online: 2 December 2009
Ó Springer Science+Business Media B.V. 2009
Abstract The interaction of seven novel substituted mero-
cyanine dyes, i.e. 1-methyl-4-[2-(3-methoxy-4-hydroxyphenyl)
ethenyl)]pyridinium iodide, 1-methyl-4-[2-(3,5-dimethoxy-
4-hydroxyphenyl)ethenyl)]pyridinium iodide, 1-methyl-4-
[2-(4-dimethylaminophenyl)ethenyl)]pyridinium iodide, their
quinoide forms as well as 1-methyl-4-[2-(3-methoxy-4-
oxocyclohexadienilydene)ethylidene]-1,4-dihydropyridine,
1-methyl-4-[2-(3,5-dimethoxy-4-oxocyclohexadienilydene)
ethylidene]-1,4-dihydropyridine, with a-CD, c-CD as well
as functionalized c-cyclodextrin phosphate sodium salt is
studied by the methods such as UV–Vis and fluorescence
spectroscopy, linear-polarized infrared (IR-LD) spectroscopy
of oriented colloids in nematic host, 1H- and 13C-NMR
spectroscopy, HPLC ESI tandem mass spectrometry, scan-
ning electron and tunneling microscopy, powder X-ray dif-
fraction as well as thermal methods. A formation of the 1D
and 2D ‘‘supramolecular polymers’’ with nanosizes is found.
The dyes are adsorbed on the CDs surface and form a hex-
agonal microcrystalline sub-structures. Remarkable fluores-
cence properties depending of the type of the substituent in
the dyes, in solid-state are observed.
Keywords Cyclodextrins ꢀ Self-assembly ꢀ Organic dyes
Introduction
The optical and nonlinear optical properties (NLO) of
organic and polymer materials are currently under intensive
study as a result of their importance and variety application
for fundamental science, material research, nanotechnology
and industry [1–10]. Major research efforts are towards the
searching for new molecules possessing large NLO polar-
izability, as well as controlling molecular orientation to
influence bulk properties. Organic molecules, such as
quinoide forms of the merocyanine dyes, having conjugated
electron systems or low-lying charge transfer (CT) exited
states often possess extremely large second-order NLO
polarizability [11–16]. However, the enormous potential of
these molecules often cannot be utilized because of unfa-
vourable alignment in the crystalline phase. In the case of
second harmonic generation (SHC), second-order suscep-
tibility vanishes for centrosymtnetic crystals. Many differ-
ent approaches have been taken to counter this problem.
The strategy for using of the chiral molecule ensures for-
mation of a noncentrosymmetric crystal and physically
guarantees a non-vanishing of the second-order suscepti-
bility, but not necessarily a large one [11–16]. Another
strategy for the tuning of the NLO properties in the bulk is
using the host–guest systems with macromolecular matri-
ces, such as cyclodextrins (CDs) [17]. The p-nitroaniline-b-
CD inclusion complex generates second harmonic radiation
when exposed the 106 lm output of a Nd-YAG laser. The
conversion efficiency is 2–4 times higher, that this of an
urea, usually used as standard. However, the formation of
the inclusion complexes depends on the cavity size of the
CDs as well as the reaction conditions. The application of
Electronic supplementary material The online version of this
article (doi:10.1007/s10847-009-9712-9) contains supplementary
material, which is available to authorized users.
¨
B. Ivanova (&) ꢀ M. Lamshoft ꢀ M. Spiteller
¨
Institut fu¨r Umweltforschung, Universitat Dortmund,
Otto-Hahn-Strasse 6, 44221 Dortmund, Germany
e-mail: BIvanova@chem.uni-sofia.bg
R. Nikolova ꢀ P. Tsanova ꢀ I. Petkov
Faculty of Chemistry, Sofia University St. Kl. Ohridski,
1, J. Bourchier Blvd, 1164 Sofia, Bulgaria
P. Ivanov
Institute of Organic Chemistry, BAS, Acad. G. Bonchev,
Str. bloc 9, 1113 Sofia, Bulgaria
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J Incl Phenom Macrocycl Chem (2010) 67:317–324
the stibazolium salts as guest molecules in host–guest sys-
tems with cyclodextrins has been used as strategy in crystal
engineering for obtaining photodimeric products [17]. The
interaction of 4-[(1-methyl-4(1H)-pyridinylidene)-ethyli-
dene]-2,5-cyclohexadien-1-one with modified b-CD has led
to the formation of the inclusion complex at molar ratio 1:1.
The wide application of cyclodextrins and their derivatives
in optical and nanotechnologies have already been dis-
cussed, thus giving a wide area for future investigations in
this respect [18].
absorbances of the guest molecule bands, the rheological
model, the nature and the balance of the forces in the
nematic liquid crystal suspension system, as well as the
morphology of the suspended particles have also been dis-
cussed [11–16].
HPLC–ESI–MS/MS analysis. The analyses of the
samples were performed with a Thermo Finnigan surveyor
LC-Pump. Compounds were separated on a Luna C18 col-
umn (150 9 2 mm, 4 lm particle size) from Phenomenex
(Torrance, CA, USA). The mobile phase consisted of water
? 0.1% HCOOH (A) and acetonitrile ? 0.1% HCOOH (B)
using a gradient program presented in Table 1. The com-
pound was detected via UV and a TSQ 7000 (Thermo
Electron Corporation, Dreieich, Germany) mass spectrom-
eter. The spectra were obtained using the TSQ 7000
equipped with an ESI ion source and operated with the
following conditions: capillary temperature 180 °C; sheath
gas 60 psi and spray voltage 4.5 kV. 1 mg/ml of the sample
was dissolved in acetonitrile and injected into the ion source
by an auto sampler (Finnigan Surveyor). The data were
processed by using the Excalibur 1.4 software.
Therefore, we have studied in detail the interaction of the
seven substituted derivatives of merocyanine dyes with a-,
c-cyclodextrin (a-CD (1), c-CD (2)) and the functionalized
derivative, c-cyclodextrin phosphate sodium salt (2a)
(Scheme S1, supplementary materials s.m.). The synthe-
sized eighteen novel systems are elucidated both in solution
and in solid-state by means of methods such as UV–VIS
and fluorescence spectroscopy, IR-LD spectroscopy of ori-
1
ented colloids in nematic host, H- and 13C-NMR spec-
troscopy, HPLC ESI tandem mass spectrometry, scanning
electron microscopy (SEM), scanning tunneling microscopy
(STM), powder X-ray diffraction (XRD) as well as thermal
methods.
1H- and 13C-NMR measurements, referenced to sodium
3-(trimethylsylyl)-tetradeuteriopropionate, were made at
298 K with a Bruker DRX-400 spectrometer using 5 mm
tubes and D2O as solvent.
Experimental
Electronic (UV–Vis) and fluorescence spectra were
recorded on a Tecan Safire Absorbance/Fluorescence
XFluor 4 V 4.40 and Evolution 300 spectrophotometers,
operating between 190 and 900 nm, both in the solid state
and in solution at a concentration of 2.5 9 10-5 M, using
0.0921 cm quartz cells.
Materials and methods
Conventional and polarized IR-spectra were measured on a
Thermo Nicolet FTIR-spectrometer (4000–400 cm-1
,
2 cm-1 resolution, 200 scans) equipped with a Specac wire-
grid polarizer. Non-polarized solid-state IR spectra were
recorded using the KBr disk technique. The oriented sam-
ples were obtained as a colloid suspension in a nematic
liquid crystal ZLI 1695. The theoretical approach, as well as
the experimental technique for preparing the samples and
the procedures for polarized IR-spectra interpretation and
the validation of this new linear-dichroic infrared (IR-LD)
orientation solid-state method for accuracy and precision
has been presented previously [11–16]. The influence of the
liquid crystal medium on peak positions and integral
The thermal analyses were performed in the range of
300–500 K on a Differential Scanning Calorimeter Perkin-
Elmer DSC-7, and a Differential Thermal Analyzer DTA/
TG (Seiko Instrument, model TG/DTA 300). The experi-
ments were carried out at a scanning rate of 10 K/min
under an argon atmosphere.
The elemental analysis was carried out according to the
standard procedures for C and H (as CO2, and H2O) and N
(by the Dumas method).
SEM experiments were performed on A HITACHI
S-3500 N instrument.
Table 1 UV-VIS spectra of the systems studied in solution
CDs/dyes
k (nm), (em [L mol-1 cm-1])
Dye-1a Dye-1b
Dye-1c
Dye-1d
Dye-1e
Dye-2
a-CD
c-CD
384 (10345) 269 (11231) 391 (12561) 481 (1132) 380 (1456)
466 (982) 321 (1021)
270 (14567) 288 (11341) 290 (13461) 315 (1267) 286 (11345) 320 (1321) 288 (16781) 350 (1345) 382 (1871)
421 (1672)
413 (2351)
282 (2318)
311 (789)
Funcionalized c-CD 361 (1011)
345 (1356)
277 (992)
318 (1172)
360 (1892)
425 (2341)
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J Incl Phenom Macrocycl Chem (2010) 67:317–324
319
Scanning tunneling microscopy (STM) experiments were
performed by using an Easyscan STM System with a Pt- Ir
tip fabricated by Nanosurf AG of Switzerland and carried
out with a sample bias voltage of ?400 mV.
continuous stirring and heating at 40 °C for 24 h. After
leaving to stand, red crystals were obtained from the result-
ing red solution and were filtered off and dried under air.
(Found: C,72.08; H, 7.80; N,8.92; [C19H25N2Cl] calcd.:
C,72.02; H, 7.95; N, 8.84%). The HPLC ESI MS–MS data
show a formation of one reaction product with peak at
abundance time of 11.2 min. The most intensive signal in the
positive mass spectrum is that of the peak at m/z 281.77,
corresponding to the singly charged cation [C19H25N2]?
with a molecular weight of 281.47. The TGV and DSC data
in the temperature range of 300–500 K showed an absence of
X-ray powder diffraction (XRD) patterns were obtained
using a Rigaku MiniFlex powder diffraction system,
equipped with a horizontal goniometer in the h/2 - h mode
(Tokyo, Japan). The X-ray source was nickel-filtered K-a
˚
emission of copper (1.54056 A). Samples were packed into
an aluminum holder using a back-fill procedure and were
scanned over the range of 50–6° 2 - h, at a scan rate of 0.5°
2 - h/min. Using a data acquisition rate of 1 point per
second, the scanning parameters equate to a step size of
0.0084° 2 - h. Calibration of each powder pattern was
effected using the characteristic scattering peaks of alumi-
num at 44.738 and 38.472° 2 - h.
1
the included solvent molecules. H-NMR data: d = 3.44,
2.21, 2.20, 1.59 ppm (t, 2H, m, 4H, t, 3H,0 N-C0H2CH2
CH2CH3), AA0BB0 signals dAA , 6.44, 2H, H-2 , H-6 ), dBB
0
0
,
7.18, 2H, H-30, H-50; AB-signals 6.55 1H, H-8, 7.41 1H, H-7,
3
JAB = 17.0 Hz, AA0BB0 signals dAA 7.55, 2H, H-2, H-6,
0
BB , 8.11 ppm, 2H, H-3, H-5. 13C-NMR data: d = 46.33,
0
d
Theoretical calculations
35.1, 30.22, 31.2 (N-CH2CH2CH2CH3), 115.11 (d, C-7),
120.88 (d, C-30, C-50), 122.55 (s, C-10), 122.69 (d, C-3, C-5),
132.33 (d, C-20, C-60), 143.99 (d, C-2, C-6), 145.18 (d, C8)
and 155.81 ppm (s, C-4).
Quantum chemical calculations were performed with the
GAUSSIAN 98 and Dalton 2.0 program packages [19, 20].
The output files are visualized by means of the ChemCraft
program [21]. The geometries were optimized at the sec-
ond-order Moller-Pleset perturbation theory (MP2) level,
using the 6-31??G** basis set. The molecular geometries
of the studied species were fully optimized by the force
gradient method using Bernys’ algorithm. For each struc-
ture, the stationary points found on the molecule potential
energy hypersurfaces were characterized using standard
analytical harmonic vibrational analysis. The absence of
imaginary frequencies (i.e., negative eigenvalues of the
second-derivative matrix) confirmed that the stationary
points correspond to minima on the potential energy hyper-
surfaces. The calculated vibrational frequencies and infra-
red intensities were checked to establish which kind of
performed calculations agreed best with the experimental
data. The MP2/6-31??G** data are presented in the result
and discussion part of the manuscript, where a modifica-
tion of the results using the empirical scaling factor 0.8929
is made to achieve better correspondence between the
experimental and the theoretical values. The UV spectra of
the compound in the gas phase and in aqueous solution are
obtained by CIS/6-311??G** and TDDFT calculations.
The ‘‘supramoecular polymers’’ of the CDs with the dyes
were obtained after mixing of the equimolar amounts of each
of the components in 20 mL aqueous solutions under con-
tinuous stirring and heating at 40 °C for 20 min. The
obtained solutions rest at normal conditions for 2 weeks. The
corresponding polymers, thus obtained (Fig. 1) were filtered
off and dried on air at room temperature. In these conditions
the interaction of the dyes with b-CD leads to a faster crys-
tallization of the b-CD, which known structure was con-
firmed by single crystal X-ray diffraction.
Results and discussion
The electronic spectra of the a-CD and c-CD displays
‘‘transparency’’ in the whole range within 200–800 nm,
whereas the corresponding c-cyclodextrin phosphate sodium
salt is characterized with a band (262 nm, e = 1189
L mol-1 cm-1) originated of n ? p* transition of the P=O
group (Fig. 2a and b). The corresponding UV–VIS spectra of
the starting dyes are characterized with the CT band\s within
390–500 nm with the em values of 2000–5700 L mol-1 cm-1
(Fig. 2c). The observed sub-component bands is a result of
the presence of monomeric dye and dimeric H-type aggre-
gates [17, 22, 23]. The UV–VIS spectra both in solution and
in solid-state show a disappearance of the CT bands, typical
for the monomeric species (Fig. 2a).
Synthesis
The Dye-1a-e was obtained by the synthetic scheme shown
in [11–16]. The 1-butyl-4-[2-(4-dimethylaminophenyl)
ethenyl]pyridinium chloride (Dye-2) was synthesized by
mixing of the 2.35 g (10.0 mmol) 1-butyl-4-methylpyr-
idinium chloride and 1.22 g (10.0 mmol) 4-dimethylami-
nobenzaldehyde in 50 ml toluol. In addition 0.77 g
(10.0 mmol) of ammonium acetate was also added under
The molecular status of the systems a-CD-dye is examined
using solid-state fluorescence measurements (Fig. 3). The
corresponding measurements in solution are also performed.
Both in both condense phases the systems are characterized
with same properties. Charge transfer emission of solids was
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J Incl Phenom Macrocycl Chem (2010) 67:317–324
Fig. 1 Microscopic
photographs of a-CD/(Dyes-1a–
Dyes-1c) systems under UV-
irradiation as well as of c-CD/
Dye-2 and functionalized c-CD/
Dye-2 (Dye-2a)
Fig. 2 a UV–Vis spectra of systems a-CD/Dye-1a (1), a-CD/Dye-1b
(2), a-CD/Dye-1c (3) in solution, Solid-state UV–Vis pectrum of
a-CD/Dye-1a (4); b of the 1-butyl-4-[2-(4-dimethylaminophenyl)eth-
enyl]pyridinium chloride (Dye-2) (1), c-CD/Dye-2 (2) and function-
alized c-cyclodextrin phosphate sodium salt/Dye-2 (3); c UV–Vis
spectra of the pure Dyes-1a–Dyes-1c, i.e. 1-methyl-4-[2-(3-methoxy-
4-oxocyclohexadienilydene)ethylidene]-1,4-dihydropyridine (1);
1-methyl-4-[2-(3,5-dimethoxy-4-oxocyclohexadienilydene)ethylidene]-1,
4-dihydropyridine (3) and 1-methyl-4-[2-(4-dimethylaminophenyl)eth-
enyl)]pyridinium iodide (3) in aqueous solution at 2.5.10-5 mol/L
concentration and 1-cm quartz cell
shown at 525, 543 and 580 nm, respectively. These results
suggest that the observed shift in the fluorescence peak could
be due to the specific properties of the systems. The com-
pounds posses solid-state fluorescence properties, untypically
for the each of the starting materials [24].
s.m.). According to previous investigations the dye-cyclo-
dextrin interaction often leads to a formation of the inclusion
complexes with the same molar ratio [5–8, 25–28]. However
our mass spectrometric data show only the peaks at m/z of the
pure CDs (Fig. S2, s.m.), thus indicating only the weak Van
der Waals interactions between the CDs and the dyes, which
is in contrast to cases, where the inclusion complexes are
obtained.
The performed quantitative determination of the compo-
nents in the a-CD-dye systems, using the standard linear plot
method, show that in all cases the molar ratio 1:1 (Fig. S1,
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J Incl Phenom Macrocycl Chem (2010) 67:317–324
321
Fig. 3 Fluorescence spectra of
a-CD/Dyes-1a (red line (1)),
a-CD/Dyes-1b (blue line (2))
and a-CD/Dyes-1c (green (3))
systems in solid-state;
Photographs of the systems
without and under UV-
irradiation, show the effect of
the UV-light on their
fluorescence properties
Fig. 4 UV-Vis spectra of the systems c-CDs 1-butyl-4-[2-(4-dim-
ethylaminophenyl)ethenyl]pyridinium chloride with c-cyclodextrin
(Dye-2) (1) and its functionalized derivative (Dye-2a) (2) in aqueous
solutions with concentration 2.5 9 10-4 mol/L and quartz cell with
thickness of 1 cm; Photographs of the systems Dye-2 and Dye-2a
without and under UV-irradiation
The Dye-2 is characterized with absorption bands 266,
287 and 451 nm belonging to K- and B- bands of the
aromatic (pyridyl- and pheny-) fragments as well as the CT
band (Fig. 4). The corresponding e values are 12 341, 2455
and 7351 L mol-1 cm-1, respectively. The data are in
good agreement also with the theoretical electronic spec-
trum of the dye in aqueous solution, obtained by means of
calculations at TD-DFT level of theory, giving bands at
260, 285 and 450 nm, respectively.
cyclodextrin:dye 1:1, the quantitative analysis shows that the
ratio of the c-CD:dye in the system Dye-2 is 1:1.33, whereas
in the second system (Dye-2a) the ratio of 1:1 is obtained.
This means that part of the c-CD rests non-reacted with the
system during the interaction of the c-CD with the dye. This
result raised the questions about identifying the form with the
excess of the organic dye in the complex with c-CD, as well
as whether and to what extent the obtained fluorescence
properties are affected? Additional experimental data are
required in order to answer these questions. The electronic
spectra of the systems studied are summarized in Table 1.
The self-assembly of the CDs in the presence of the dyes
is studied by the IR-LD spectroscopy of oriented colloids
(s.m.). The comparison between the data of the pure CDs
and those of corresponding systems CDs-dyes is per-
formed. In addition the theoretical quantum chemical
calculations of the vibrational properties of -butyl-4-[2-(4-
dimethylaminophenyl)ethenyl]pyridinium cation are per-
formed (s.m.). The obtained data show that in the pure
CDs, a reasonable degree of macro orientation of
suspended CDs is observed, as a result of the layers of
herringbone-like motifs, typical for crystalline compounds
The UV–Vis spectra of the complexes of the Dye-2 with
the two c-CDs studied show that their interaction leads to a
batochromic shift of 32 nm of the CT band in the first
case, accompanied with the hypochromic effect of
800 L mol-1 cm-1 in the Dye-2 system. On the contrary, the
system-modified c-CD/Dye-2 (Dye-2a) is characterizedwith
the hypsochromic effect of 64 nm for the CT band. On the
other side only the system Dye-2 is characterized with the
fluorescence properties in the solid state giving a band at
493 nm [24]. We performed for the purpose a quantitative
determination of the organic dye in the two complexes using
the standard linear plot method. Independently from the fact
that the synthesis of the complexes is obtained at molar ratio
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J Incl Phenom Macrocycl Chem (2010) 67:317–324
Fig. 5 Non-polarized IR-
spectra of c-CD (1),
c-cyclodextrin phosphate
sodium salt (3); Difference
IR-LD spectra of c-CD (2) and
c-cyclodextrin phosphate
sodium salt (4)
(4)
(3)
(2)
(1)
3500
3000
2500
2000
1500
1000
500
Absorbance / Wavenumber (cm-1)
(Fig. 5). In contrast, the difference IR-LD spectra of the
CDs-dyes systems are characterized with series of positive
and negative IR-bands, belonging to the included molecule
of the dyes, whereas the IR-bands of the CDs are elimi-
nated. These data show that the herringbone-like structure
of the CDs is distorted.
image in Fig. 6, which could be interpreted in support of
the presence of microcrystallines of the dye. These data
corroborate with the spectroscopic findings (vide supra),
indicating the presence of excess of the dye in the system.
Comparing the data for corresponding pure c-CDs and
treated with the dyes systems, the surfaces of the systems
Dye-2 and Dye-2a are different (Fig. 6). Such difference in
surface morphologies indicated that the presence of the
1-butyl-4-[2-(4-dimethylaminophenyl)ethenyl]pyridinium
chloride changed the macrostructures or the self-assembly
of the CDs studied.
In order to compare the thermal stabilities of the systems
CDs-dyes the thermal analysis is performed. The ‘‘com-
plexes’’ started to lose weight at 388 °C (a-CD/Dye-1a),
344 °C (a-CD/Dye-1b) and 413 °C (a-CD/Dye-1c), and at
about 500 °C they lost within 32–66%, of their original
weights. DTA experiments are performed and they indi-
cated that the systems display exothermic peaks within
265–344 °C. The ‘‘complexes’’ c-CD/Dye-2 and modified
c-CD/Dye-2, started to lose weight at 300 and 321 °C,
respectively. About 500 °C they lost 44 and 72%, respec-
tively, of their original weight. DTA experiments were
performed and they indicated that the c-CD/Dye-2 system
displays an exothermic peak at 312 °C and a weak exo-
thermic peak at 213 °C. A clear-cut exothermic peak at
431 °C was obtained for the system Dye-2a.
In order to elucidate this phenomenon we are preformed
the powder X-ray diffraction experiment. The obtained
reflections in the XRD patterns (Fig. S7, s.m.) are similar to
those of corresponding dyes. They indicate that some dif-
ferences are observed in the presence of a-CD but the small
amount of the excess of the dye is characterized with the
ordered microcrystalline structure. The formation of the 2D
supramolecular structure of the a-CD is accompanied with
the parallel crystallization of the dye on the surface.
˚
The obtained reflections appearing at 2h 20.1° (3.21 A),
˚
˚
In order to compare the surface morphologies of the
systems studied, as well as for the starting materials, the
SEM experiments are performed. The SEM images in
Fig. 6 gave the hexagonal ‘‘printing’’ macrostructures
information as well as underlined sheet structures of all of
the systems studied [24].
22.6° (3.10 A) and 31.1° (2.13 A) in the XRD pattern in
Fig. S7 (s.m.) are similar to those of the 1-butyl-4-[2-(4-
dimethylaminophenyl)ethenyl]pyridinium chloride at 2q)
˚
˚
˚
20.3° (3.66 A), 22.2° (3.00 A) and 36.2° (2.48 A). They
indicate that some differences are observed in the presence
of c-CDs but the small amount of the excess of the dye is
characterized with the ordered microcrystalline structure.
This result is in accord with the proposed statement that the
excess of the dye in the system Dye-2 is microcrystallines.
The formation of the changed macrostructure of the CD in
Obviously, difference in surface morphologies of the
a-CD and the systems a-CD-dye indicated that the pres-
ence of the macrostructures or the self-assembly of the
host. Moreover, regular hexagons are observed in the SEM
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J Incl Phenom Macrocycl Chem (2010) 67:317–324
323
Fig. 6 SEM images of systems
studied
the system Dye-2 is accompanied with the parallel crys-
tallization of the dye on the surface of the c-CD complex.
STM is a convenient and widely employed method for the
elucidation of the certain microstructures of the supramo-
lecular aggregates. Visualization of the STM experiments of
the complexes was also performed. A nanometer-sized
molecular wire with the size of ca. 10–15 nm is seen. The
STM images provide direct evidence for the formation of
the 2D supramolecular pseudo polymer structure in all of the
systems. A nanometer-sized molecular wire with the size of
ca. 5–10 nm is seen for the systems c-CD/Dye-2 and func-
tionalized c-CD/Dye-2a systems (Fig. S8, s.m.).
ratio of the cyclodextrin:organic dye 1:1.33 and 1:1,
respectively. Nanometer-sized molecular wire with approx-
imately 5–10 nm length was obtained for both systems
studied. Theexcessof the dye in thefirst case form hexagonal
microcrystalline structures on the ‘‘supramolecular poly-
mers’’. Remarkable fluorescence properties at 412 nm in
the system c-cyclodextrins/dye are detected, which are not
present in the corresponding pure c-CD and in 1-butyl-4-[2-
(4-dimethylaminophenyl)ethenyl]pyridinium chloride, both
in solution and in the solid-state.
Supproting information
Supporting information includes the linear dependency
data for standard solutions, mass spectrometric data, linear
polarized spectroscopic data; theoretical quantum chemical
calculations, powder X-ray diffraction data and STM,
respectively.
Conclusions
In conclusion, we could draw that the interaction of substi-
tuted
4-[(1-methyl-4(1H)-pyridinylidene)-ethylidene]-2,
5-cyclohexadien-1-one and 1-butyl-4-[2-(4-dimethylamin-
ophenyl)ethenyl]pyridinium chloride with a-CD, c-CD as
well as functionalized c-cyclodextrin phosphate sodium salt,
leads to the following results: (i) The interaction of substi-
Acknowledgements B.K. wishes to thank the Alexander von
Humboldt Foundation for the Fellowship. M.S. and B.K. wishes to
thank the DAAD for a grant within the priority program ‘‘Stability
Pact South-Eastern Europe’’. M.S. thanks the DFG grand SP 255/21-
1. P.I., B.K. and R.N. thanks the National Research Fund of Bulgaria
(TK01/0167 and DO-02-82/2008-UNION)
tuted
4-[(1-methyl-4(1H)-pyridinylidene)-ethylidene]-2,
5-cyclohexadien-1-one with smaller a-cyclodextrin from
leads to formation of 2D nanosize ‘‘supramolecular poly-
mers’’. The dyes are adsorbed on the CD surface and form a
hexagonal microcrystalline sub structures. Molar ratio
a-CD:dye is 1:1. Nanometer-sized molecular wires in the 2D
structure are with approximately 10–15 nm lengths. Fluo-
rescence properties in solid-state are observed at 525, 543
and 580 nm, respectively, depending of the type of the
substituent in the dyes. (ii) The interaction of c-CD and its
phosphate sodium salt with 1-butyl-4-[2-(4-dimethylamin-
ophenyl)ethenyl]pyridinium chloride leads to the formation
of ‘‘supramolecular polymers’’ of both c-CDs with the molar
References
1. Szejtli, J., Osa, T.: Comprehensive Supramolecular Chemistry,
vol. 3. Pergamon/Elsevier, Oxford, UK (1996)
2. Saenger, W.: In: Atwood, J.L., Davies, J.E., MacNicol, D.D.
(eds.) Inclusion Compounds, vol. 2, p. 231. Academic, New York
(1984)
3. Bender, M., Komiyama, M.: Cyclodextrin Chemistry. Springer-
Verlag, New York (1978). Chapter 3
123

324
J Incl Phenom Macrocycl Chem (2010) 67:317–324
4. Szejtli, J.: Instroduction and general overview of cyclodextrin
chemistry. Chem. Rev. 98, 1743–1754 (1998)
5. Rekharsky, M., Inoue, Y.: Complexation thermodynamics of
cyclodextrins. Chem. Rev. 98, 1875–1918 (1998)
18. Latini, G., Parrott, L., Brovelli, S., Frampton, M., Anderson, H.,
Cacialli, F.: Cyclodextrin-threaded conjugated polyrotaxanes for
organic electronics: the influence of the counter cations. Adv.
Func. Mater. 18, 2419–2427 (2008)
6. Connors, K.A.: The stability of cyclodextrin complexes in solu-
tion. Chem. Rev. 97, 1325–1358 (1997)
7. Hapiot, F., Tilloy, S., Monflier, E.: Cyclodextrins as supramolec-
ular hosts for organometallic complexes. Chem. Rev. 106, 767–
781 (2006)
8. Dodziuk, H.: Cyclodextrins and Their Complexes. Chemistry,
Analytical Methods, Applications. Wiley-VCH Verlag GmbH&Co.
KGaA, Weinheim (2006)
9. Pistolis, G., Malliaris, A.: Size effect of a, x-diphenylpolyenes on
the formation of nanotubes with c-cyclodextrin. J. Phys. Chem. B
102, 1095–1101 (1998)
19. Frisch M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb,
M.A., Cheeseman, J.R., Zakrzewski, V.G., Montgomery Jr., J.A.,
Stratmann, R.E., Burant, J.C., Dapprich, S., Millam, J.M., Dan-
¨
iels, A.D., Kudin, K.N., Strain, M.C., Farkas, O., Tomasi, J.,
Barone, V., Cossi, M., Cammi, R., Mennucci, B., Pomelli, C.,
Adamo, C., Clifford, S., Ochterski, J., Petersson, G.A., Ayala,
P.Y., Cui, Q., Morokuma, K., Salvador, P., Dannenberg, J.J.,
Malick, D.K., Rabuck, A.D., Raghavachari, K., Foresman, J.B.,
Cioslowski, J., Ortiz, J.V., Baboul, A.G., Stefanov, B.B., Liu, G.,
´
Liashenko, A., Piskorz, P., Komaromi, I., Gomperts, R., Martin,
R.L., Fox, D.J., Keith, T., Al-Laham, M.A., Peng, C.Y., Nana-
yakkara, A., Challacombe, M., Gill, P.M.W., Johnson, B., Chen,
W., Wong, M.W., Andres, J.L., Gonzalez, C., Head-Gordon, M.,
Replogle, E.S., Pople, J.A. Gaussian 98, Gaussian, Inc., Pitts-
burgh, PA, (1998)
10. Pistolis, G., Balomenou, I.: Cyclodextrin cavity size effect on the
complexation and rotationaldynamicsof the laserdye 2, 5-diphenyl-
1, 3, 4-oxadiazole: from singly occupied complexes to their nano-
tubular self-assemblies. J. Phys. Chem. B 110(33), 16428–16438
(2006)
11. Kolev, Ts., Koleva, B.B., Spiteller, M., Mayer-Figge, H.,
Sheldrick, W.S.: The crystal structure and optical properties of 1-
methyl-4-[2-(4-hydroxyphenyl)ethenyl]pyridinium dihydrogen-
phosphate: new aspects on crystallographic disorder and its effect
on polarized solid-state IR spectra. Dyes Pigment. 79, 7 (2008)
12. Kolev, T.M., Yancheva, D.Y., Stoyanov, S.I.: Synthesis and
spectral and structural elucidation of some pyridinium betaines of
squaric acid: potential materials for nonlinear optical applica-
tions. Adv. Func. Mater. 14, 799–805 (2004)
13. Kolev, T., Koleva, B.B., Spiteller, M., Sheldrick, W.S., Mayer-
Figge, H.: 2-Amino-4-nitroaniline, a known compound with
unexpected properties. J. Phys. Chem. 111A, 10084–10089 (2007)
14. Koleva, B.B., Kolev, Ts., Seidel, R.W., Mayer-Figge, H., Spi-
teller, M., Sheldrick, W.S. On the origin of the color in the solid
state. Crystal structure and optical and magnetic properties of
4-cyanopyridinium hydrogensquarate monohydrate. J. Phys. Chem.
112(A), 2899–2905 (2008)
15. Koleva, B.B., Kolev, T., Seidel, R.W., Spiteller, M., Mayer-Figge,
H., Sheldrick, W.S.: Self-assembly of hydrogensquarates: crystal
structures and properties. J. Phys. Chem. 113A, 3088–3095 (2009)
16. Kolev, T., Koleva, B.B., Seidel, R.W., Spiteller, M., Sheldrick,
W.S.: New aspects on the origin of color in the solid state.
Coherently shifting of the protons in violurate crystals. Cryst.
Growth Des. 9, 3348–3352 (2009)
20. ‘‘DALTON’’, a molecular electronic structure program, Release
2.0 (2005), http://www.kjemi.uio.no/software/dalton/dalton.html
21. Zhurko, G.A., Zhurko, D.A.: ChemCraft: Tool for treatment of
chemical data, Version 08 (2005)
22. Lohr, A., Lysetska, M., Wu¨rthner, F.: Supramolecular stereomuta-
tion in kinetic and thermodynamic self-assembly of helical mero-
cyanine dye nanorods. Angew. Chem. Int. Ed. 44, 5071 (2005)
23. Wu¨rthner, F., Yao, S., Beginn, U.: Highly ordered merocyanine dye
assemblies by supramolecular polymerization and hierarchical
self-organization. Angew. Chem. Int. Ed. 42, 3247–3250 (2003)
24. Ueno, A.: Review: fluorescent cyclodextrins for molecular sens-
ing. Supramol Sci 3, 31–36 (1996)
25. Wenz, G., Han, A., Mueller, G.: Cyclodextrin rotaxanes and
polyrotaxanes. Chem. Rev. 106, 782–818 (2006)
26. Harata, K.: Stuctural aspekt of the stereodifferentitation in solid-
state. Chem. Rev. 98, 1803–1828 (1998)
27. Lindner, K., Saenger, W.: Crystal and molecular structure of
cyclohepta-amylose dodecahydrate. Carbohydr. Res. 99, 103–115
(1982)
28. Saenger, W., Jacob, J., Gessler, K., Steiner, T., Hoffman, D.,
Sanbe, H., Koizumi, K., Smoth, S., Kakaha, T.: Structures of the
common cyclodextrins and their larger analogouse beyond the
doughnut. Chem. Rev. 98, 1787–1802 (1998)
17. Wang, Y., Eaton, D.: Optically non-linear organic molecules
cyclodextrin inclusion complexes. Chem. Phys. Lett. 120, 441
(1985)
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