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Utility to Humans Centered in the Torus shaped form, differing interior sizes allow for encapsulation of many target compounds. β-cyclo-dextrin
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Cyclodextrins!
A powerpoint presentation- 4-05-05:evening
Presenting-Addison CarterAdvisor- Dr David Kammler
Cyclodextrins:
α-cyclodextrin- 5 sugar moleculesβ-cyclo-dextrin- 6 sugar moleculesγ-cyclodextrin- 7 sugar molecules
Simply cyclized α-d-1,4-glucopyranose sugar
Utility to HumansCentered in the Torus shaped form, differing interior sizes allow for encapsulation of many target compounds.
β-cyclo-dextrin
Nonpolar centralcavity
Secondary Hydroxyl rim
Primary Hydroxyl Rim
An ether-like central section creates ideal conditions forpreferential spacial arrangement of non-polar compoundsin the central section
The exterior wall retains polar (hydrophilic) sugar-likecharacter which allows for solubility of the cyclodextrin molecule both with and without a guest molecule
Bacillus CirculansCyclodextrin 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
Targets:
Real World AppsDrugs
-solubility-photostability-oxidation prevention-ease of handling
Synthesis-site-selective binding-chiral selectivity-general protecting group
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?
Polymerization
Terephthalic acid polymerization
Methyl MethacrylatePolymerization
Phase Typed Polymerization
Bulk Solution
Emulsion Dispersion
One Phase
Two Phase
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
Alternative Mode to Emulsion PolymerizationDispersion Polymerization:
Non-polar Polar
Some small number of monomericunits move into the aqueous phaseto be polymerized.
-rate-polydispersity-phase separation
Essentially this is the question of how much monomer will transverse the interstitial zone between the oiland water layers
A Potential Solution: Cyclodextrins as Phase
Transfer Agents
Non-Polar
Polar
Complexation
Polymerization
InitiatorIn this the cyclodextrin modulates the transverse activity of the monomer.
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
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 targetmolecules
-partition coefficients for those solvated chemicals
AbsorptionMolar AbsorptionConstant
Length of Absorbing sample
Concentrationof absorbing sample
Substrate Choice
- UV-active- polymerizable- soluble- complexable- available from the local stock of chemicals
All these are either mono- or di- substitutedbenzene rings which are known to be quiteUV-active. They are also cheap and polymerizable
Styrene Terephthalic acid p-aminobenzoic acid
p-pentylstyrene
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
Terephthalic Acid, the First alternateProblem: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
AKA: The 1.5 month time warp
AnInterlude
Concerning the Repair of a Certain Piece of Instrumentation
Vital!to the Continuation of Senior Project
Epsilon Values of PABA in Four SolventsDetermined at .0001M PABA in named solvent
E In Ether
EEE 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.
Partitioning Behavior Compared With and without cyclodextrin
.264 at 273nm
.268 at 273nm1 M equivalent CD
Amount of Cyclodextrin the issue?
.202 at 276nm
10 Molar equivalents of cyclodextrin presentyields lower absorbancethan the previous 1 Molar equivalent system
-instead of complexing with the PABA the peak shifting right may be a sign of ethyl acetate complexation
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