Transcript
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:
+
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
+
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?
top related