Using light to detect metalsUsing light to detect metals
Laura I. Saucedo
http://i138.photobucket.com/albums/q261/newt_album/visiblespectrum.gif
Heavy Metal Ion ContaminationHeavy Metal Ion Contamination
� In chemical solutions� In underground water supplies
Today:Today:
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But first…But first…
Let’s talk about colorLet’s talk about color
Under UV light
a: b:
Why does substance ‘b’ change color?Why does substance ‘b’ change color?
� A) Because our eyes are playing tricks on us.
� B) Light interference � C) Because it now reflecting blue� D) Because of electronic excitation
Under UV light
a: b:
What are some ways that molecules can utilize energy?What are some ways that molecules can utilize energy?
http://preloaders.net/en/search/arrow%20rotating ; http://www2.ess.ucla.edu/~schauble/MoleculeHTML/CO2_html/CO2_page.html
Singlet vs TripletSinglet vs Triplet
Spin multiplicity = 2S + 1S = ms1 + ms2
Singlet Triplet
Absorption
InternalConversionVibrationalRelaxation
Radiative Decay
Absorption
IntersystemCrossing Vibrational
Relaxation
Radiative Decay
PhosphorescencePhosphorescence
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Electronic_Spectroscopy/Jablonski_diagram
Absorption
IntersystemCrossing Vibrational
Relaxation
Radiative Decay
Intersystem Crossing?Intersystem Crossing?
http://employees.csbsju.edu/cschaller/Reactivity/photochem/PCfluorescence.htm
What is the relationship of energy to wavelength?What is the relationship of energy to wavelength?� A) E = hc/λ� B) E = hcλ� C) E = hλ/c� D) E = hc/λ2
λ is inversely proportional to Energyhttp://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html
FluorescenceFluorescence
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Electronic_Spectroscopy/Jablonski_diagram
Absorption
VibrationalRelaxation
Radiative Decay
Stokes ShiftStokes Shift
http://dc440.4shared.com/doc/3mKIGd6e/preview.html
Fluorescein
Rhodamine
Coumarin
Common fluorescent molecules:Common fluorescent molecules:
What do these molecules have in common that cause them to fluoresce?
a) Ether groupsb) Each contain a
benzene ringc) Extended π
systemd) Electronegative
atoms
BODIPYBODIPY
4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene
Peña, E. et al., Chem. Commun. 2010, 46, 5103-5105 Tram, K. et al., Dyes Pigments, 2009, 392
Meltola, N. et al., J. Fluoresc. 2004, 635-647 Jiang, X. et al., Org. Biomol. Chem. 2012, 6861-6865
Placing this into a polar solvent:Placing this into a polar solvent:
QuenchedQuenched
http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/Chapter__2%3A_Introduction_to_organic_structure_and_bonding_II/Section_2.3%3A_Non-covalent_interactions
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2
2+3+
Optical Properties Optical Properties
0
0.02
0.04
0.06
0.08
0.1
348 398 448 498 548
AB
S
λ
Absorption
Hex
Ben
DCM
THF
Acetone
Acetonitrile
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
348 398 448 498 548
Fluo
resc
ence
vol
ts
λ
EmissionsHex
Ben
DCM
THF
Acetone
Acetonitrile
Optical PropertiesOptical Properties
What do these spectra tell you?What do these spectra tell you?
� A) Some of the absorbed energy is lost through non-radiative decay
� B) Polar solvents are interacting with the molecule
� C) A and B� D) none of the above
Future WorkFuture Work
� Currently purifying a protected:
� Working to cleave disulfide bond.
Rate My PresentationRate My Presentation
� A) Best, most informative presentation of your entire life
� B) It was a good informative presentation� C) Meh� D) Are you still up there?� E) BOOO!
Questions?Questions?
This material is based upon work supported by the National Science Foundation under Grant Number DUE-1140469.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Degenerate?Degenerate?
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