Interaction of aza-aromatic compounds with porous silica beads and controlled porous glasses as studied by absorption and fluorescence spectroscopy [Elektronische Ressource] = Absorptions- und fluoreszenzspektroskopische Untersuchungen der Wechselwirkung von Aza-aromaten mit porösen Kieselgelen und kontrolliert porösen Gläsern / vorgelegt von Abeer Salah Eldeen Elsherbiny

Informations

• Publié par: eberhard_karls_universitat_tubingen
• Publié le: 01 janvier 2006
• Nombre de lectures: 11
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Interaction of Aza-aromatic Compounds with Porous Silica Beads
and Controlled Porous Glasses as Studied by Absorption
and Fluorescence Spectroscopy


Absorptions- und fluoreszenzspektroskopische Untersuchungen
der Wechselwirkung von Aza-aromaten mit porösen
Kieselgelen und kontrolliert porösen Gläsern


Dissertation

der Fakultät für Chemie und Pharmazie
der Eberhard Karls Universität Tübingen
zur Erlangung des Grades eines Doktors
der Naturwissenschaften

2006

vorgelegt von
Abeer Salah Eldeen Elsherbiny
















Tag der mündlichen Prüfung: 27.6.2006
Dekan : Prof. Dr. S. Laufer
1- Berichterstatter : Prof. Dr. D. Oelkrug
2- Berichterstatter : PD. Dr. H.-J. Egelhaaf



















Die vorliegende Arbeit wurde am Institut für Physikalische und Theoretische Chemie der
Universität Tübingen unter Anleitung von Herrn Prof. Dr. Dieter Oelkrug durchgeführt, dem
ich für seine Unterstützung und sein Stetiges Interesse danke.








To

MY PARENTS AND MY FAMILY

















ACKNOWLEDGMENT

I am deeply thankful to God, by the grace of whom the progress of this work was
possible. I wish to express my gratitude thanks to Prof. Dr. D. Oelkrug for his great interest,
encourgement and his stimulating discussions throughout the progress of this work.
I would like to thank Dr. H.-J. Eglhaaf for suggesting the topic point, continuous guidance,
great efforts and frutiful advice during the work. Also, I would like to thank Prof. Dr. K.
Albert group for suppling the porous and coated silica and help during the HPLC
measuremnets. Also, I wish to express my deep thanks to Graduiertenkollegs 'Chemie in
Interphasen' for suppoting this work.

I wish also to extend my thanks to the authorities of Institute of Physical and Theoritical
Chemistry, Tübingen University for facilities afford, without which the present work would
never have been completed. Also, I wish to thanks my husband for his stand beside me during
this work.











Contents
Page

1. Introduction ………....................................................................................................1
1.1. Stationary phase …………………………………………………………………..2
1.2. Probe molecules…………………………………………………………………...5
2. Theory………………………………………………………………………................7
2.1. Electronic absorption spectroscopy…………………………………………….....7
2.2. Fluorescence spectroscopy………………………………………………………..8
2.3. Fluorescence anisotropy…………………………………………………………..9
2.3.1. Effect of multiple scattering on fluorescence anisotropy……………...……….10
2.3.2. Effects of rotational diffusion on fluorescence anisotropy:
The Perrin equation……………………………………………………………..11
2.4. Fluorescence lifetime or decay time…………………………………………….11
2.5. Collisional quenching of fluorescence……………………………………….....12
2.6. Kinetics of opposing reactions in interphase systems…………………………..13
2.7. Simplified description of reaction kinetics and equilibria
in interphase systems…………………………………………………………..15
2.7.1. Neglection of back reaction…………………………………………………….17
2.8. Selectivity factor in chromatography…………………………………………..18
3. Experimental………………………………………………………………………….20
3.1. Materials…………………………………………………………………………20
3.1.1. Fluorescent probes (adsorbates)…………………………………………………20
3.1.2. Solvents……………………………………………………………………….....21
3.1.3. Stationary phases………………………………………………………………..21
3.1.3.1. Silica…………………………………………………………………………..21
3.1.3.1.1. Non-modified (bare) silica…………………………………………………..21
3.1.3.1.2. Modified (Coated) silica………………………………………………….....22
3.1.3.1.2.1. Modified with alkyl chains (C30 – alkyl chains)………………………….22
3.1.3.1.2.2. Modified with active groups (amino groups)……………………………..22
3.1.3.1.2.3 Modified with polymers…………………………………………………..24
3.1.3.2 Determination the amine concentration at the modified silica surfaces……....25
3.1.3.3. Controlled Porous Glass (CPG)………………………………………………25
3.1.3.3.1. Geltech Controlled Porous Glass (PGG)…………………………………....25
3.1.3.3.2. Porous Vycor Glass (PVG)…………………………………………………25
3.2. Instruments……………………………………………………………...…...........26
3.2.1. Absorption spectrophotometer…………………………………………...……..26
3.2.2. Fluorometer………………………………………………………………..........26
3.2.3. Centrifuge…………………………………………………………………........27
3.2.4. High-performance liquid chromatography (HPLC)……………………………27
3.3. Measurements……………………………………….……………………………27
3.3.1. Characterization of the adsorption…………….…….…...………………..........27
3.3.1.1. Silica as stationary phase…………………….….………...………………….27
3.3.1.1. CPG as a stationary phase………………………..…………………………...27
3.3.2. Kinetics measurements…………………………….………….....….………….29
3.3.2.1. Silica as adsorbent…………………………………………......….…….........29
3.3.2.2. Silica as reactant………………………………………………..………........29
3.3.2.3. PVG as adsorbent……………………………………………….…………...29
4. Results and Discussions………………………………………………….................31
4.1. Characterization of probes in solution……………………………………..…31
4.1.1. Selection of probes…………………………………………………………….31
4.1.2. Electronic transitions…………………………………………………….…….31
4.1.2.1. Spectra of neutral probes……………………………………………….........32
4.1.2.2. Influence of solvent acidity on probe spectra……………………..……........34
4.1.2.3. Fluorescence quantum yields and decay times.….…………………………..39
4.1.2.4. Fluorescence anisotropy of probes…………………………………………...41
4.2. Spectroscopic characterization of the adsorbed state……....………………...47
4.2.1. Controlled porous glass as adsorbent………………………….……………...49
4.2.1.1 Porous Vycor glass ………………………………….………….…………...49
4.2.1.2. Porous Geltech glass …………………………………………………….....54
4.2.3. Non-modified silica beads as adsorbent……………………………………....58
4.2.4. Modified silica as adsorbent…………………………………………………..67
4.2.4.1 Silica modified with alkyl chains (silica C30)………………………….........67
4.2.4.2. Silica modified with polymers…………………….………………………...71
4.2.4.2.1. TBB-coated silica ……………………………..………………...................71
4.2.4.2.2. Polymerized divinylbenzene (DVB)-coated silica ………….......................72
Discussion ……………………………………………………………….........74
4.3. Adsorption equilibria……………………………………………………………77
4.3.1. Controlled porous glass as adsorbent…………………………………….....77
4.3.1.1. Porous Vycor glass (PVG) ………………………………………………..77
4.3.1.2. Porous Geltech glass (PGG) ……………………………………………....77
4.3.2. Non-modified silica beads as adsorbent……………………………………..78
4.3.3. Modified silica beads as adsorbent……….………………………………….82
4.3.3.1. Modified with polymer….…………………………………………………82
4.3.3.1.1. TBB-coated silica..…………………….…………………………………82
4.3.3.1.2. Polymerized divinylbenzene (DVB)-coated silica …………….………...84
4.3.4. HPLC measurements….……………………………………………………...84
Discussion…………….……………………………………………………....87
4.4. Adsorption kinetics……………………………………….……………………....89
4.4.1. Adsorption at porous Vycor glass (PVG)……………….…………………..89
4.4.1.1. Adsorption of AC at PVG……………………………….…………………89
4.4.1.2. Adsorption of 1-DBA at PVG……………………………..……………….92
4.4.1.3. Adsorption of 3-DBA at PVG……………………………..……………….96
4.4.2. Adsorption at non-modified silica beads……………………..……………...100
Discussion……………………………………………………..……………107
4.5. Accessibility of probes attached to silica surfaces…………………..…………..108
4.5.1. Influence of O on the fluorescence intensity and lifetime of adsorbates..…..109 2
4.5.1.1. Acridine…………………………………………………………………….109
4.5.1.2. Dibenzacridines…………………………………………………………….112
4.5.1.2.1. 1,2,7,8-Dibenzacridine…………………………………………………...112
4.5.1.2.2. 3,4,5,6-Dibenzacridine…………………………………………………...117
Discussion…………………………………………………………………119
4.5.2. Chemical reactivity at silica surfaces………………………………………..120
4.5.2.1. Introduction………………………………………………………………..120
4.5.2.2. Binding and mobility……………………………………………………....122
4.5.2.3. Reaction kinetics…………………………………………………………..125
Discussion………….........................................................