Supramolecular behaviour of substituted pyridinium salts and merocyanine dyes [Elektronische Ressource] / von Diana Ster

Diana Ster

Informations

• Publié par: martin-luther-universitat_halle-wittenberg
• Publié le: 01 janvier 2007
• Nombre de lectures: 54
• Poids de l'ouvrage: 5 Mo

Extrait

Supramolecular behaviour of substituted pyridinium salts
and merocyanine dyes


Dissertation


Zur Erlangung des akademischen Grades

doctor rerum naturalium (Dr. rer. nat.)

vorgelegt der

Naturwissenschaftlichen Fakultät II – Chemie und Physik
der Martin-Luther-Universität Halle-Wittenberg

von Frau Dipl.-Ing. Diana Ster

geb. am 01.02.1979 in Baia Mare



Gutachter:
1. Prof. Dr. G. Israel
2. Prof. Dr. R. Zentel

Halle (Saale), den 17.10.2007
urn:nbn:de:gbv:3-000012638
[http://nbn-resolving.de/urn/resolver.pl?urn=nbn%3Ade%3Agbv%3A3-000012638]Contents

1. Introduction and problems 1
1.1. Theoretical part and literature 1
1.1.1. Ionic liquid crystals 1
1.1.1.1. General aspects 1
1.1.1.2. Pyridinium salts 3
1.1.1.3. Stilbazolium salts 6
1.1.2. Merocyanine dyes 7
1.1.2.1. Supramolecular behaviour 7
1.1.2.2 Spectral properties 10
1.2. Introduction of the synthesized and investigated compounds 12

2. Results and discussions 14
2.1. Synthesis 14
2.1.1. Synthesis of merocyanine dyes 14
2.1.2 Synthesis of N-alkyl-4'-substituted-stilbazolium compounds 18
2.1.3 Synthesis of N-alkyl-4- and -3-phenyl-pyridinium salts 20
2.2. Properties of N-alkyl-4- and -3-substituted-pyridinium salts 21
2.2.1. Liquid crystalline properties 21
2.2.1.1. N-alkyl-4-phenyl-pyridinium salts 21
2.2.1.2. N-alkyl-3-phenyl-pyridinium salts 29
2.2.1.3. N-alkyl-4-methyl-pyridinium salts 33
2.2.2. UV/Vis investigations of N-alkyl-3- and -4-substituted pyridinium salts 35
2.2.3. Lyotropic properties of N-octadecyl-4-methyl-pyridinium iodide 39
2.3. Properties of N-alkyl-4'-substituted-stilbazolium salts 44
2.3.1. Liquid crystalline properties 44
2.3.1.1. N-alkyl-4'-hydroxy-stilbazolium halides 44
2.3.1.2. N-alkyl-4'-methoxy-stilbazolium halides 46
2.3.1.3. N-alkyl-stilbazolium halides 47
2.3.2. Spectral properties 49
2.3.2.1. Photoisomerization of N-alkyl-4'-substituted-stilbazolium salts 49
2.3.2.2. Concentration dependence measurements of N-alkyl-4'-substituted-
stilbazolium salts 54
2.4. Properties of merocyanine dyes 56
2.4.1. Spectral investigations 56
2.4.1.1. Protonation-deprotonation equilibrium 56
2.4.1.2. Cis-trans isomerization of merocyanine dyes 59
2.4.1.3. Aggregation behaviour of merocyanine dyes in solution 61
2.4.1.4. Aggregation behaviour of merocyanine dyes in solid state 66
2.4.1.5. Solvatochromic effect 67
2.4.1.6. Substituent effect 70
2.4.1.7. Fluorescence investigations of merocyanine dyes 71
2.5. Photo-E.M.F. measurements of N-alkyl-3- and -4-substituted pyridinium
salts and stilbazolium compounds 72

3. Summary 74

4. Experimental part 79
General procedures and analytical data of the synthesized compounds 80
4.1. Synthesis of stilbazolium dyes 6 – 9 83
4.1.1. Dialkylated diesters 1a – d 83
4.1.2. Monoesters 2a – d 84
4.1.3. Alcohols 3a – e 85
4.1.4. Alkyl halides 4a – e 86
4.1.5. Picolinium salts with N-(2,2-dialkyl ethyl) substituents 5a – e 88
4.1.6. N-(2,2-dialkyl ethyl)-4'-oxy-stilbazolium dyes 6a – e 89
4.1.7. N-(2,2-dialkyl ethyl)-4'-oxy-3'-alcoxy-stilbazolium dyes 7 – 9 94
4.2. Synthesis of stilbazolium dyes with secondary N-alkyl chain 97
4.2.1. Alcohols with secondary alkyl chain 10a – e 97
4.2.2. Halides with secondary alkyl chain 11a – e 98
4.2.3. Picolinium salts with secondary N-alkyl chain 12a – g 99
4.2.4. 4'-Hydroxy-stilbazolium dyes with secondary N-alkyl chain 13a – g 101
4.3. Synthesis of N-alkyl-4'-substituted-stilbazolium salts 107
4.3.1. N-alkyl-4-methyl-pyridinium salts 14a – n 107
4.3.2. N-alkyl-4'-oxy- and -hydroxy-stilbazolium compounds 15a – n 111
4.3.3. N-alkyl-4'-methoxy-stilbazolium salts 16a – f 120
4.3.4. N-alkyl-stilbazolium salts 17a – f 124
4.3.5. N-docosyl-4'-nitro-stilbazolium bromide 19 128
4.3.6. N-docosyl-4'-dimethylamino-stilbazolium bromide 20 129
4.4. Synthesis of N-alkyl-4- and -3-phenyl-pyridinium salts 131
4.4.1. N-alkyl-4-phenyl-pyridinium salts 21a – j 131
4.4.2. N-alkyl-3-phenyl-pyridinium salts 22a – f 136

5. References 140

6. Appendix 144























Abbreviations and symbols

AFM Atomic Force Microscopy
A Absorbance
bs Broad singlet
c Concentration
cmc critical micelle concentration
Col Columnar hexagonal h
Col Columnar rectangular r
Cr Crystalline state
cwmc Critical wormlike micellar concentration
d Layer periodicity distance
d Doublet
D Distance between the alkyl chains or aromatic cores
dec. Decomposition
D-band Dimer band
DBr Deuterium bromide
DMF Dimethyl formamide
DMSO Dimethyl sulfoxide
DN Donor number
D O Deuterium oxide 2
DSC Differential Scanning Calorimetry
E Transition energy
E(t) Dimroth parameter
h Planck’s constant
H Hexagonal phase I
H Inverted hexagonal phase II
HCl Hydrochloric acid
HI Hydrogen iodide
HOMO Highest occupied molecular orbital
I Cubic phase of spherical micelles I
Iso Isotropic state
ITC Isothermal titration calorimetry
I Inverted cubic phase of spherical micelles II
J Coupling constant
KOD Kalium deuteroxide
l Path length of the cell
L Lamellar phase α
L Diameter of the fibre
LC Liquid crystals
LiAlH Lithium aluminium hydride 4
LiCl Lithium chloride
m Complex multiplet
M Mesophase M
MC Merocyanine dye
M-band Monomer band
MeOH Methanol
m. p. Melting point
n Number of carbon-atoms in the alkyl chain
N Nematic phase
N Avogadro’ s number A
N Columnar nematic phase col
N Discotic nematic phase d
NMR Nuclear magnetic resonance
P Phosphourous
r.t. Room temperature
R Correlation coefficient
r Ionic radius X¯
SmA Smectic A phase
SmC Smectic C phase
SmG Smectic G phase
t Triplet
T Temperature
T Clearing temperature c
T Melting temperature m
V Bicontinuous cubic phase I
V Inverted bicontinuous phase II
U(t) Voltage
Z Kosower parameter
Mesophase temperature range
λ Wavelength
ε Absorption coefficient
ε Dielectric constant (at 25°C) r
Dipole moment
∆H Transition enthalpy
δ Chemical shift
κ Specific conductivity
χ Brooker’s parameters R, B
2D Two dimensional
3D Three dimensional















TIntroduction

1. Introduction and Problems

1.1. Theoretical part and literature

1.1.1 Ionic liquid crystals

1.1.1.1. General aspects

Ionic liquid crystals (Ionic LCs) can be considered as materials combining the
properties of liquid crystals and ionic liquids. The ionic character means that some of the
1 properties of ionic LCs may differ significantly from that of conventional liquid crystals.
Ionic liquids is now a commonly accepted term for low-temperature molten salts. The
low vapour pressure of the ionic liquids as well as miscibility with water and other solvents
1makes ionic liquids good candidates as solvents in organic reactions. Properties of ionic
liquids can be controlled to a large degree by variation of cation and the anion. The effect of
the altering the anion has been quite widely investigated. Increasing the size of the anion
gives rise to a reduction in the melting points of salts through reduction of Coulombic
attraction contributions to the lattice energy of the crystal and increasing charge-transfer of
the ions. The size and shape of the cation also play an important role in determining the
melting points of the salts. A large range of ionic liquids form liquid-crystalline phases by
increasing the amphiphilic character of the aromatic unit and by substitution with longer alkyl
2
chain.

Liquid crystals are partially ordered, anisotropic fluids, thermodynamically located
3between the three dimensionally ordered crystal state and the isotropic liquid. There are two
classes of liquid crystals: thermotropic phases which occur by heating, and lyotropic phases
which are induced in the presence of a solvent. Some compounds exhibit both thermotropic
and lyotropic phases, as in the case of amphotropic molecules. Thermotropic liquid crystals
can be enantiotropic, in which the liquid crystalline phase occurs in heating and