Download presentation
Presentation is loading. Please wait.
Published byRosaline Reed Modified over 9 years ago
1
Cyclodextrins! A powerpoint presentation- 4-05-05:evening Presenting-Addison Carter Advisor- Dr David Kammler
2
Cyclodextrins: α-cyclodextrin- 5 sugar molecules β-cyclo-dextrin- 6 sugar molecules γ-cyclodextrin- 7 sugar molecules Simply cyclized α-d-1,4-glucopyranose sugar
3
Utility to Humans Centered in the Torus shaped form, differing interior sizes allow for encapsulation of many target compounds. β-cyclo-dextrin
4
Nonpolar central cavity Secondary Hydroxyl rim Primary Hydroxyl Rim An ether-like central section creates ideal conditions for preferential spacial arrangement of non-polar compounds in the central section The exterior wall retains polar (hydrophilic) sugar-like character which allows for solubility of the cyclodextrin molecule both with and without a guest molecule
6
Bacillus Circulans Cyclodextrin glucosyltransferase- Extracted v. in situ In reaction vats at pH 6.0-7.0 at 35-40 °C. The source of cyclodextrins Within starch producing plants
7
Targets:
8
Real World Apps Drugs -solubility -photostability -oxidation prevention -ease of handling Synthesis -site-selective binding -chiral selectivity -general protecting group
9
Real World Apps II Environmental Problems -well water contamination -hypothetically use for heavy metal contamination Chemical Analysis with HPLC -selective complexation with different target substrates allows for different flow rates for the various target substrates Enzyme Mimicry?
10
Polymerization Terephthalic acid polymerization Methyl Methacrylate Polymerization
11
Phase Typed Polymerization Bulk Solution Emulsion Dispersion One Phase Two Phase
12
Trouble with polymerization Surfactants -used in emulsion polymerization, one of the main modes of plastic production -phosphate/sulphate anion base The problem: Not many readily available natural break down paths
13
Alternative Mode to Emulsion Polymerization Dispersion Polymerization: Non-polarPolar Some small number of monomeric units move into the aqueous phase to be polymerized. -rate -polydispersity -phase separation Essentially this is the question of how much monomer will transverse the interstitial zone between the oil and water layers
14
A Potential Solution: Cyclodextrins as Phase Transfer Agents Non-Polar Polar Complexation Polymerization Initiator In this the cyclodextrin modulates the transverse activity of the monomer.
15
So then, what's the next Question, Considering: -dispersion polymerization is well documented -with many substrates -in many solvent pairs -with some phase transfer catalysts -only one person will be working on this project as a four credit class over the course of a semester -numbers on the equilibria of substrates/substrate-cyclodextrin pairs is not readily available -we do not have an NMR available to examine complexation however, -we do have a Ultraviolet-Visible spectrophotometric machine -cyclodextrin doesn't absorb UV-Vis spectrum light
16
Thus, -We can find concentrations of photo responsive chemicals in solution -in the aqueous layer (as well as the organic layer) with and without Cyclodextrin for each of our target molecules -partition coefficients for those solvated chemicals Absorption Molar Absorption Constant Length of Absorbing sample Concentration of absorbing sample
17
Substrate Choice - UV-active - polymerizable - soluble - complexable - available from the local stock of chemicals All these are either mono- or di- substituted benzene rings which are known to be quite UV-active. They are also cheap and polymerizable Styrene Terephthalic acid p-aminobenzoic acid p-pentylstyrene
18
Para-amino benzoic acid(PABA) -Locally available -PABA is very UV active -soluble in water -soluble in ethyl acetate The problem -Too UV active in Ether, Ethyl Acetate, Water, 1-Octanol.1 M?.01 M?.001 M?.0001 M? Dilution to this level allowed for a scale within machine detection limits. - Not an effective use of time considering the interest was to study partitioning with an eye toward polymerization which would be served via other routes
19
Terephthalic Acid, the First alternate Problem:Solubility.1 M.01 M.001 M Styrene, the Second Alternative Unfortunately past this molarity the accuracy of the scale would be called into question for the amount of solvent that was acceptable. Problem: Time -Only preliminary testing at.01 M was conducted however absorbance was within the detection envelope for the instrument. -Much lower prep time would result in larger volume of data
20
AKA: The 1.5 month time warp An Interlude Concerning the Repair of a Certain Piece of Instrumentation Vital! to the Continuation of Senior Project
21
Epsilon Values of PABA in Four Solvents Determined at.0001M PABA in named solvent E In Ether E E E In Ethyl Acetate In Water In 1-octanol 20180 at 275 nm 11970 at 284 nm 15650 at 275 nm 13480 at 266 nm Values taken at the most convenient location along the graph of absorptivity, λ max.
22
Partitioning Behavior Compared With and without cyclodextrin.264 at 273nm.268 at 273nm 1 M equivalent CD
23
Amount of Cyclodextrin the issue?.202 at 276nm 10 Molar equivalents of cyclodextrin present yields lower absorbance than the previous 1 Molar equivalent system -instead of complexing with the PABA the peak shifting right may be a sign of ethyl acetate complexation
24
The Road from here: Choice in substrate -late found resources have recipes in which pure substrate is used as the non-polar phase example:styrene ON aqueous cyclodextrin mixed -mono-substituted benzene rings -biphenyl Time to mix -late found materials point to time scale of days for complexation Substituted cyclodextrin -better match
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.