Transcript Ppt0000003 - Southwestern Oklahoma State University

Can Publishable Research Results Be
Produced in Effective Undergraduate
Chemistry Labs?
Tim Hubin
Southwestern Oklahoma State University
Outline
• Background
– The Classical Inorganic Chemistry Lab
– Hubin’s Research Experience/Interests
– Motivations for a Project-Based Lab Course
• Project-Based Lab Design at SWOSU
– Synthetic Scheme
– Course Mechanics
• Weekly Schedule
• Specific Assignments
• Rubrics
• Outcomes
– Grades
– Course Evaluations
– Research Publications
I. Background
• The Classical Inorganic Chemistry Lab
– From the 2008 Revision of the ACS Committee on Professional Training “Inorganic
Chemistry Supplement”
Practical Topics
“The goal of the inorganic laboratory is to give students experience with a range of techniques
used in the synthesis and characterization of inorganic compounds and to give them experience
in preparing and analyzing various classes of inorganic compounds…”
“…Among the techniques that are recommended for inclusion in the inorganic laboratory are the
following:
•
Synthetic Methods that make use of inert atmospheres (dry box/bag, Schlenk methods), a
high temperature furnace/heated tube, a vacuum line, a high pressure autoclave, and
electrochemical apparatus.
•
Purification Methods such as column/ion exchange chromatography, sublimation,
recrystallization and resolution of optically active compounds.
•
Characterization Methods that involve measurements of magnetic susceptibility,
conductivity, oxidation-reduction potentials, X-ray diffraction, IR, UV-vis, NMR (variable
temperature, multinuclear, multidimensional), optical rotation, ESR, Mössbauer, and mass
spectrometry.”
ACS Guidelines
“In the ideal case, experiments should be more than a list of instructions to be followed.
Instead, they should illustrate how characterization methods provide insight into
fundamental electronic structure and structure-property relationships (by studying families
of related compounds for instance)…The list below provides examples of complexes that
have been described in the chemical education literature, as a starting point for
development of laboratory projects.”
• Coordination Compounds – [Co(NH3)5Cl]Cl2, Mn(acac)3, [Co(en)3]Cl3, CrCl2(H2O)4+, Cr(acac)3,
[Cr(NH3)6](NO3)3], Cu(O2CMe3)2•H2O, [Co(en)2Cl2]Cl, [Co(o-phen)3]Br2, Co(salen),
Mo2(O2CMe)4, K4Mo2Cl8.
• Organotransition Metal Compounds – (η6-1,3,5-Me3C6H3)Mo(CO)3, Cp2Fe2(CO)4,
Ir(Cl)(CO)(PPh3)2, Cp2Ni, PtCl2(1,5-cyclooctadiene), [Pd(Cl)( (η3-allyl)]2, Cp2Fe,
Rh(Cl)(CO)(PPh3)2, Fe3(CO)12.
• Main Group Element Compounds – BH3:NH2(tBu), B(OR)3, C60, GeH4, Sn(Cl)2(R)2,
Ph2PCH2CH2PPh2, K2S2O8, PhBCl2, K(C2B9H11),
ICl3, [I(pyridine)2](NO3), [PCl4][SbCl6], Me3N:BF3, siloxane polymers.
• Solid State Compounds – YBa2Cu3O7, VO(PO4)(H2O)2, a zeolite, CrCl3.
• Bioinorganic Compounds – Ni(glycinate)n(2-n)+, copper(II) tetraphenylporphyrin,
Pd(nucleoside)2(Cl)2, Cu(saccharin)2(H2O)4, Cu(glycinate)2, cis-platin, cobaloxime model
complexes.
• Special Topics – quantum dots, nanocrystals, templated synthesis of nanowires, selfassembled monolayers.
Inorganic Lab Texts
My First Inorganic Lab Syllabus
Compound Type
Coordination Chemistry
Coordination Chemistry
Template Synthesis
Bioinorganic
Bioinorganic
Bioinorganic
Main Group
Coordination Chemistry
Organometallic
My Research Experience and Interests
•
Coordination Chemistry = new chemical compounds formed by the
binding of simpler, yet distinct, molecules by “non-covalent” bonds
•
Ligand = atom, ion, or molecule that can donate a pair of electrons
to a metal ion :C≡O: H2Ö: R3P:
Coordination Compound= formed by the donation of an electron
pair from the ligand to the metal
•
•
•
Example: H3N: + Ni2+
H3N—Ni2+
Ligand
Metal Complex
Example: AlCl3 + 6 H2O
Al(H2O)63+ + 3 Cl-
Complex Ligands Exploiting Topology and Rigidity:
Cross-Bridged Tetraazamacrocycles
O
n
NH HN
O
H
H
CH3CN
NH HN
N
N
H
n
N
RX
CH3CN
N
H
n = 0 or 1 independent ly
RX = MeI or BnBr
n
n
cyclam
N
N+
R
H
H
n
n
R
N+
N
2X
-
NaBH4
95% EtOH
N
N
N
N
R
if R = Bn
P d/C, H2
n
N
HN
HOAc
NH
N
R
n
n
Weisman et al. J. Am. Chem. Soc. 1990, 112, 8604.
Weisman et al. J. Chem. Soc., Chem. Commun. 1996, 947.
n
Metal Complexes
[Ni(Me2B14N4)(acac)]+
Co(Me2B12N4)Cl2
Fe(Bn2B12N4)Cl2
Application #1 Aqueous Oxidation Catalysis
• Problem: Catalyst Decomposition
– Transition Metal Complexes decompose in H+ or OH• Acidic Conditions
H+
R3N
• Basic Conditions
R3N
• Oxygenated Conditions
R3NH+
M
M
R3N
OH -
M
R3N
O 2/H2O
+
+
M
M(OH)n
R3N
+
• Kinetic Stability of Our Complexes: 1 M HClO4
Metal
CuII
Ligand
Me2B14N4Me6
Me2B14N4
Me2B13N4
Me2B12N4
t1/2
> 8 yr
> 6 yr
>8 yr
30 h
Metal
CuII
Ligand
Me414N4
cis-14N4Me6
trans-14N4Me6
t1/2
2s
2s
22 d
MxOy
Electrochemical Studies
• Ligands stabilize metals in
multiple oxidation states
Cu
• Mn(Me2B14N4)Cl2
identified as active catalyst
Ni
catalyst
H2O2
Co
Fe
Patents: US 6,218,351
US 6,387,862
US 6,608,015
Mn
2
1.5
1
0.5
0
-0.5
-1
Potential (V)
-1.5
-2
-2.5
Application #2 MRI Contrast Agents
• Paramagnetic metal complexes (usually Gd3+) used to modify
relaxivity of water protons in tissue giving contrasted images
– Complex must be stable, because Gd3+ is toxic to humans
O
O
O
O
DOTA
O
N
N
N
N
O
Gd-DOTA
NO
O O
OH2
Gd
O
O
N O
O
N
N
O
O
O
– Gd3+ is 9–coordinate, ligand is octadentate, only one site can interact with H2O
– Relaxivity (contrast) should improve with more open sites available to interact
O
with water
O
Result:
stable complex with
CH
3
N
O
NH HNN
N2 N
roughly twice the relaxivity
N
N
OH
OH
Gd OH2
of Gd-DOTA
HO
N
N
N
NH HN
O
L
L
OH2
ON
N
CH3
O
L
N
Patent: US 6,656,450
Application #3 Anti-HIV Drugs
• Background
– “Bis-” or linked-tetraazamacrocycles exhibit activity against HIV
– AMD3100 and its Cu and Zn complexes are in clinical trials
NH HN
NH
N
N
NH HN
HN
NH HN
NH
Zn
N
2+
NH HN
Bridger, et. al. J. Biol. Chem. 2001, 276, 14153.
– Metal binds to CXCR4 co-receptor of the
immune cells through aspartate residues
− Recent studies suggest cis-binding of the
aspartate residues, requiring folded ligand
Sadler, et. al. J. Am. Chem. Soc. 2002, 124, 9105.
2+
Zn
N HN
Current progress
• Cross-bridged bis-tetraazamacrocycles
– Cross-bridge dictates cis-folded structure thought needed
– Goal is stronger and more selective binding to CXCR4
coreceptor
CH3
N
N
H3C
N
N
N
N
N
N
N
N
Zn
N
N
L
L
N
R
N
Zn
N
L
N
L
R
– Ligand, Cu2+, and Zn2+ complexes synthesized
– Meta-xylyl linked analogue and complexes synthesized
– Currently undergoing initial anti-HIV screening
Motivations for a Project-Based Inorganic Lab
• Advantages of the “Classical” Lab
– Coverage of all different types of inorganic compounds and techniques possible
– Straightforward course design—like any other chemistry lab
• Prep one lab at a time
• All students working on the same lab at the same time
• Grade one kind of lab report at a time
– Can choose inexpensive materials, methods, and instrumentation
• Disadvantages of the “Classical” Lab
–
–
–
–
–
Doesn’t focus on instructor’s expertise throughout
Students make something, run a characterization or two, and throw it away
Lacking “Discovery” element
Lacking in-depth study of any one system
Unlike what “real chemists” do
Motivations for a Project-Based Inorganic Lab
• Disadvantages of the Project-Based Lab
– Can’t cover all types of inorganic compounds
– Complex course design—unlike any other chemistry lab
• Prep for multiple experiments
• All students not working on the same lab at the same time
• Each Lab report is unique, at least for parts of the semester
– More expensive/rare materials, methods, instrumentation may be required
• Advantages of the Project-Based Lab
–
–
–
–
–
–
Does focus on instructor’s expertise throughout
Students become invested with semester long series of related experiments
Focus on the “Discovery” element of learning science
Centered on an in-depth study of one system
Exactly like what “real chemists” do
Opportunity to write-up, present, (and publish original) research
II. The Project-Based
Inorganic
Lab at SWOSU
Inorganic Chemistry
Lab 2007
• Synthetic Scheme: 9-step synthesis completed in 8 weeks
NH
NH2
NH
NiCl2 6H2O
O
O
2+
2+
NH2
NH
H
H2 O
NH2
N
NH
NaBH4
H
Ni
NH
2+
Ni
NH
H2O
NH2
complexation
NH
NH
H2O
demetallation
NH
reduction
template reaction
(1,4,8,11-tetraazacyclotetradeca-1,3-diene)nickel(II)
1,4,8,11-tetraazacyclotetradeca-1,3-diene
N,N'-bis(3-aminopropyl)ethylenediamine
KCN, 
Ni
H2 O
N
NH
(N,N'-bis(3-aminopropyl)ethylenediamine)nickel(II)
O
O
I
NH
HN
H
NH
HN
H
CH3CN
N
CH3I
N
CH3CN
N
alkylation
condensation
cyclam
1,4,8,11-tetraazacyclotetradecane
1,4,7,10-tetraazacyclodocecane (cyclen)
H3C
N
N
N
NaBH4
95% EtOH, N2
reduction
H3C
2
N
N
N
N
H 3C
N
N
4
3
tetracycle
bridged cyclam
methylated tetracycle
cis-decahydro-1H,6H,-3a,5a,8a,10a-tetraazapyrene
cis-decahydro-2a,4a,6a,8a-tetraazacyclopent[fg]acenaphthylene
3a,8a-dimethyl-cis-decahydro-5a,10a-diaza-3a,8a-diazoniapyrene
2a,6a-dimethyl-cis-decahydro-4a,8a-diaza-2a,6a-diazoniacyclopent[fg]acenaphthylene
CH3
CH3
CH3
N
N
I
1
N
CH3
CH3
N
N
N
MCl2 in glovebox
CH3CN or DMF
complexation
N
Cl
Br2
MeOH
N
Cl
N
NH4PF6
oxidation
Cl
M
M
N
N
Cl
N
CH3
CH3
5
divalent complex
PF6
6
trivalent complex
Characterization
IR
UV-Vis
Magnetic Moment
Cyclic Voltammetry
Conductance
NMR
Elemental Analysis
Mass Spectrometry
Part 1—Organic Synthesis
Course Text and Assigned Readings
Desire2Learn On-Line Quiz for each chapter for a total of 35pts out of 210pts total
Notes on the Organic Synthetic Part
• Students work in pairs to make:
– Cyclam Starting Material
– One of two possible Cross-Bridged Ligands: Bcyclam or Bcyclen
• Pre-Lab lecture prior to each lab:
–
–
–
–
Fairly short—need the time in the lab
Covers: reactions of the day, safety, techniques
Detailed “Procedure” sheets are handed out
Primary Literature and Notebook pages distributed in “Inorganic Lab Manual”
• Organic Compound Characterization
– Cyclam synthesis is one-pot, so only final product characterized
– Each step of the Bridged Ligand synthesis is worked up and characterized
– GC-Mass Spec, 1H NMR, and 13C NMR is required for each compound
• Purification techniques: column chromatography, vacuum distillation
• Each student writes two lab reports: Cyclam and Bridged Ligand
– 25pts each for a total of 50pts out of 210pts total for the class
Notes on Part 2—Inorganic Synthesis
• Student partners shuffled—keep bridged ligand, paired by metal
– Each student will make a unique complex: [Fe(Bcyclam)Cl2]PF6
– Synthetic steps and characterization organized by metal ion
• Labile M2+ salts complexed to Ligands in Inert Atmosphere Glovebox
– Cr, Mn, Fe, Co are air sensitive; Ni, Cu are not
– Bridged ligands are air/water sensitive due to extreme basicity
• Chemical Oxidation to air stable M3+ complex eases characterization
– Cr, Mn, Fe oxidized by Br2; Co oxidized with air under acidic conditions
– Ni, Cu are air stable at 2+ and will not be oxidized to 3+
Metal complexes produced in Fall 2007.
From left: Mn3+, Fe3+, Co3+, Ni2+, Cu2+.
Part 3—Inorganic Characterization
Notes on Inorganic Characterization Part
• Pre-Lab: Theory, Data Workup, and Conclusions for our Complexes for
a different technique each week—Powerpoint Lecture
- More time for pre-lab as characterization is quicker than synthesis
- I work up actual data for a different technique each week
• Students rotate to different instrument(s) each week w/parter
- SWOSU only has one instrument of each type
- Elemental Analysis and Electrospray Mass Spectrometry sent off-site
- Data Analysis for these covered during NMR slot (already know NMR)
• Handout on Procedure for each instrument/technique
- Specific to SWOSU’s instrument holdings
- Instructor (and TA) rotate among groups troubleshooting problems
• A written lab report for the Inorganic Synthesis and Characterization
is written in the same format as above. 50pts out of 210pts total.
Reporting Their Results
• Scientific Research isn’t finished until the results are communicated
• Each student prepares a manuscript containing all experimental
procedures, results, discussion, and conclusions
• “Cantaurus” (Bulldog) format is required
• Format adapted from Prof. Jonathan Frye (McPherson College)
• Each student is given a formatted template file in Word
• “Guide to Authors” adapted from Prof. Frye as well
• A general introduction and general experimental are provided
– This is not a literature course; I don’t ask them to justify the project
– The general experimental provides sources of chemicals, instrument details
• Each student prepares a poster, following a generic template
The Synthesis and Characterization of Co(AcBcyclam)PF6
Jonas Lichty and Timothy J. Hubin. Dept. of Chemistry, Southwestern Oklahoma State University
–
N
An Improved MRI Contrast Agent?
O
NO
O O
OH2
Gd
O
O
N O
O
-Modulate magnetic properties of water
-Utilize Gd3+ because of its high
magnetic moment as a result of its
seven unpaired electrons
-The more open coordination sites
available to interact with water, the
better the resolution
-Complex must be stable, because Gd3+
is toxic to humans
-Gd3+ is 9 – coordinate, ligand is
octadentate, so only one site is available
to interact with water
Mass Spectrum
O
N
O
OH2
OH2
OH2
O
N
Gd
N
N
O
4000.00 3500.00 3000.00 2500.00 2000.00 1500.00 1000.00 500.00
wavenumber
Why Cobalt? There is an abundance of information on cobalt complexes, so
comparisons can be made with similar complexes.
O
HO
N
N
N
N
NH HN
O
O
H
H
L2
N
N
N
N
H
N
BnBr
N
H
95%
N
[Co L]Cl
•
NH4PF6
MeOH
N
EtOH
C 35.31%
C 26.83%
C 35.32%
H2, Pd/C, HOAc
N
N
1. ICH2CO2Et
2. OH -
O
N
N
OH
N
OH
6.2
II
6.0
Co L
5.8
O 5.4
5.2
5.0
4.8
4.6
Ser i es1
350
400
450
H 3.80%
H 5.26%
N 10.29%
N 8.80%
N 10.31%
+
-
600
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
1.8
71
70
69
68
67
66
65
64
O
O
+ Cl
Conclusions
-The synthesized Co3+ complex of 4, 11 – diacetato – 1, 4, 8, 11 –
tetraazabicyclo[6,6,2]hexadecane was pure.
-From the UV-Vis we can conclude that AcBcyclam is a strong field ligand
-NMR, Mass Spec, and IR have all been assigned
-Cobalt is the first metal put into this ligand that gives an NMR (diamagnetic)
-X – ray crystal structure confirms predicted geometry
650
700
NMR Data
N
[Co L][PF6] + NH4
550
The energy of the lowest energy absorption
band can be used to estimate the ligand field
strengths of the ligands in the complexes.
- This has been calculated for the complex and
for cis – [CoL2]+[CO3]-. The results were nearly
identical. (both strong field ligands)
-This similarity means that the addition of the
cross bridge has not affected the ligand field
strength, even though it made the ligand more rigid.
Co
N
500
63
62
61
60
Crystal Structure [Also need Magnetic Moment and Conductance]
O
N
III
[Co L]Cl
III
5.6
N
He
H 5.19%
Overall Yield 63%
for three steps.
Purity confirmed by
Elemental Analysis
to 0.4% CHN.
Identity confirmed
by NMR comparison
to ligand
2Br-
O
MeOH/MeCN
O2, HCl, H2O
H
HN
Complex Synthesis
LH2
Pure
NaBH4
N
N
NH
+
H
N
N
Crude
[CoL][PF6]
. NH PF . MeOH
4
6
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
300
Wavelength (nm)
Overall Yield 56% for four steps.
Purity confirmed by
Elemental Analysis to 0.4% CHN.
Identity confirmed by
NMR comparison to literature.
L3
N
III
N
CH3CN
CH3CN
NH HN
Co L
N
Ligand Synthesis:
NH HN
II
N
CH3
L
CoCl2
N
6
Calculated
[CoL][PF6]
CH3
NH HN
Spectra of [CoL][PF ]
UV-Vis UV-Vis
Spectrum
OH
O
•
IRSpectrum
Spectrum
IR
for [CoL][PF6]
-Ethylene cross – bridge makes it more
“rigid”, which makes the complex more
stable
-The ligand field strength (avg strength of
metal-donor bonds) of this cross – bridged
ligand is comparable to similar ligands
without cross – bridges
-The ligand leaves two more open
coordination sites on Gd3+
Elemental Analysis
–
•
Characterization of the Complex
absorbance
N
•
Introduction
Absorbance
•
–
Acknowledgements
-Dr. Tim Hubin
--Dr. David VanderVelde, of the University of Kansas
-Dr. Steven Archibald, of the University of Hull (U.K.)
59
58
57
56
55
III. Outcomes
• Point Distribution (Fall 2009)
–
–
–
–
–
–
Ligand Synthesis Lab Reports: 2 @ 25 pts = 50 pts
Metal Complex Synthesis and Complexation Lab Report = 50 pts
Textbook On-Line Quizzes: 7 @ 5 pts = 35 pts
Poster = 25 pts
Aggregate 2006-2009 (n = 22)
Written Paper = 50 pts
10
TOTAL = 210 pts
8
6
• Grade Distribution
4
2
0
A
Spring 2006 (n = 6)
3
B
C
Fall 2007 (n = 10)
1
0
A
B
C
D
Fall 2009 (n = 6)
3
4
3
2
1
0
2
D
2
1
0
A
B
C
D
A
B
C
D
Course Evaluations by Students (n = 19)
Question 2: Initially, my interest in this subject
was…
Possible Responses
Very High (1)
High (2)
Moderate (3)
Low (4)
Very Low (5)
Number
7
7
5
0
0
Percent
37%
37%
26%
0%
0%
Aggregate Mean This
Course
Aggregate Mean
This Course
Hubin Mean F2005S2009
Chemistry/Physics
Mean
University Mean
Possible Responses Number
Very High (1)
15
High (2)
3
Moderate (3)
1
Low (4)
0
Very Low (5)
0
Aggregate Mean
1.89 This Course
Question 6: Course required meaningful
work and study.
Possible Responses Number
Strongly Agree (1)
14
Agree (2)
4
Sometimes Agree (3)
1
Disagree (4)
0
Stongly Disagree (5)
0
Question 3: At this time, my interest in this
subject is…
Percent
74%
21%
5%
0%
0%
1.32
1.57
1.67
1.74
Percent
79%
16%
5%
0%
0%
Aggregate Mean
This Course
Hubin Mean F2005S2009
Chemistry/Physics
Mean
University Mean
1.12
1.51
1.62
1.59
1.26
Question 9: Course expanded my
knowledge, comprehension, and/or skills
Possible Responses Number
Strongly Agree (1)
18
Agree (2)
1
Sometimes Agree (3)
0
Disagree (4)
0
Stongly Disagree (5)
0
Aggregate for Questions 6-20
Strongly Agree (1)
Agree (2)
Sometimes Agree (3)
Disagree (4)
Stongly Disagree (5)
Mean of the Means Items 6-20
Aggregate Mean This Course
Hubin Mean F2005-S2009
Chemistry/Physics Mean
University Mean
Percent
95%
5%
0
0
0
1.05
1.63
1.71
1.67
Question 16: Instructor demonstrated
enthusiasm for the course subject.
Possible Responses Number
Strongly Agree (1)
18
Agree (2)
1
Sometimes Agree (3)
0
Disagree (4)
0
Stongly Disagree (5)
0
Aggregate Mean
This Course
Hubin Mean F2005S2009
Chemistry/Physics
Mean
University Mean
Percent
95%
5%
0
0
0
1.05
1.62
1.47
1.47
Student Evaluation Comments
• “This has been the best lab I have ever been in…I really liked how the lab was one
long experiment.”
• “I really found this course to be a great exposure to synthetic chemistry. I have
learned many useful skills that I will continue to use.”
• “This lab has been great. It feels like I am accomplishing a lot more. I am learning
how to prepare a journal article. It has been a very good experience.”
• “I have enjoyed the way the lab is set up. Lab feels like I am accomplishing
something instead of just doing an experiment and throwing it away.”
• “The lab portion of the course was a very helpful mini research experience.”
• I love Inorganic Chemistry Lab. Sometimes it is tough, but everything is interesting.
We have fun in lab and learn a lot…
• Great lab. Required application of knowledge and skills while expanding on both.
• Excellent teaching, fantastic techniques, and clear, concise work meaningful &
relevant to subject.
• This lab made me enjoy Inorganic. It actually made me like Chem. Labs again.
• This lab required a lot of effort. Dr. Hubin is a very nice instructor but the course
work is really tough.
Publishable Work?
SPRING 2006
• “Dichloro(4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane)iron(III) hexafluorophosphate”
McClain, J. M.; Maples, D. L.; Maples, R. D.; Matz, D. L.; Harris, S. M.; Nelson, A. D.-L.; Silversides, J. D.;
Archibald, S. J.; Hubin, T. J. Acta Cryst. C, 2006, C62, m553.
•
“Synthesis and Characterization of the chromium(III) complexes of ethylene cross-bridged cyclam and
cyclen ligands” Maples, D. L.; Maples, R. D.; Hoffert, W. A.; Parsell, T. H.; van Asselt, A.; Silversides, J. D.;
Archibald, S. J.; Hubin, T. J. Inorg. Chim. Acta 2009, 362, 2084-2088.
FALL 2007 (In Preparation)
• “Chloro(4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane)copper(II) chloride”
• “Dibromo(4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane)cobalt(III) hexafluorophosphate”
Fall 2009 (In Preparation)
• “Dichloro(4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane)cobalt(III) hexafluorophosphate”
Lessons Learned
• This is a lot of work
• Things will go wrong. Will you be able to “fix” them?
– Re-extracting five water layers over the weekend
– Re-making two cobalt complexes because of an unexpected oxidation
outcome
• Consider your project carefully before diving in
– Semester-long project vs. several week project as part of “normal” lab
– Scope of project and equipment needed may make it impractical
• Rewarding for students and instructor
– Confidence
– Understanding
– Publications