Transcript Chris Roca - Harlem Children Society

Creating an Ion & Molecular Sensor By
Combining Phenyl Mercaptoacetamide &
Benzyl Mercaptoacetamide Ligands with
Preferable Metals
Submitted by: Chris Roca
Mentor: Duncan Quarless, Ph.D.
Undergraduate Asst. Mentor: Alicia Bowen
ABSTRACT
Phenyl mercaptoacetamide (PMA) & Benzyl mercaptoacetamide (BMA)
were synthesized to observe their imitative relevance for fabricating the
structure and reactivity of metallocysteinate proteins that are involved in
metal transport.
These ligands were used to observe if the type of reaction that takes place
between them and the metal cations, which are Zinc (Zn2+) and Cobalt
(Co2+), can produce an ion detecting molecule.
Xylenol Orange was used as a color indicator to determine the extinction
(metal concentration dependence) which is used from Beer’s law A= EBC
and examine the visible spectroscopy of the various solutions, which
determines the relative concentration of complexed and free indicators.
Although no major results are yet found, zinc appears to be the least
discriminate of the metal cations with respect to xylenol orange. Cobalt
showed a lower extinction than Zinc which meant more concentration was
needed than Zinc.
The purpose of such an experiment is to see if these ligands can be an
alternative for ion detection when combined with a metal, which for the
moment seems to be Zinc.
INTRODUCTION
 Ion recognition continues to be a major research goal for many
supramolecular chemist groups around the world.
 Phenyl mercaptoacetamide (PMA) & Benzyl mercaptoactamide (BMA)
are ligands or in other words they are a molecule that bonds to the
central metal atom of a compound.
 What is expected to happen is that the ligands, BMA and PMA, would
react with the metals, Zinc (Zn) and Cobalt (Co), to form a molecule that
detects specific ions when the two come into contact.
 If successful this experiment can help produce an ion detecting agent
that is a novel sulfur based ligand, and these assays will likely have
relevance in analytical, environmental chemistry, as well as biomedical
imaging and drug discovery.
CHEMICALS
 Aniline
 Benzylamine
 Thioglycolic acid (mercaptoacetic acid)
 Cobalt acetate
 Zinc acetate
 pH 5 buffer
 Methanol
MATERIALS
LAB EQUIPMENT
 Thermometers
 Weighing scales
 Assorted glassware (Volumetric flasks, Erlenmeyer flasks, Buchner funnels,
etc)
 Ultra violet Light (UV/vis) spectrophotometer
 Infrared (IR) spectroscopy apparatus
 Nuclear Magnetic Resonance (NMR) Spectroscopy apparatus
SYNTHESIS OF BMA & PMA
Phenyl Mercaptoacetamide
Benzyl Mercaptoacetamide
METHODS
 BMA & PMA were synthesized from benzyl amine and aniline,
respectively
 Samples were recrystallized from methanol
 Checked melting point of samples
 Tested purity of samples using GC-MS (gas chromatograph with mass
spectrophotometer)
 Created pH 5 buffer for use in metal reactions
 Created metal solutions using zinc acetate and cobalt acetate in
methanol
 Xylenol Orange indicator was added to metal solutions which were then
tested in uv/vis spectrophotometer to determine the extinction
coefficients for metal xylenol orange complexes
 Tested BMA & PMA using 1H NMR (nuclear magnetic resonance) to test
the purity of solutions, and to characterize the compounds
 Tested for impurities and characterization using infrared spectroscopy
Rotating Around the Carbon - Amide Bond
The Absorbance Dinstinction of Zn & Co at Different Concentrations ( W/ XO indicator)
0.4
0.35
0.3
0.25
Absorbance
Co
0.2
Co (double conc)
Zn
0.15
Zn (double conc)
0.1
0.05
0
400
450
500
550
600
-0.05
Wavelength
650
700
750
Comparison Between Co & Co (PMA) Absorbance (W/ XO Indicator)
0.4
0.35
0.3
Absorbance
0.25
0.2
Co
Co (PMA)
0.15
0.1
0.05
0
400
450
500
550
600
-0.05
Wavelength
650
700
750
Comparison Between Zn & Zn (PMA) Absorbance (W/ XO Indicator)
0.18
0.16
0.14
Absorbance
0.12
0.1
Zn
0.08
Zn (PMA)
0.06
0.04
0.02
0
400
450
500
550
600
-0.02
Wavelength
650
700
750
Cobalt Extinction in Various Concentrations (1 ml, 3 ml, and 5 ml)
0.4
0.35
0.3
absorbance
0.25
0.2
co x 1
co x 3
co x 5
0.15
0.1
0.05
0
400
450
500
550
600
-0.05
w avelength
650
700
750
RESULTS
 No major results yet found
 In the UV/vis spectrophotometer Zinc was shown to have a more
drastic extinction pattern in XO than Cobalt did in XO
 Zinc is a better candidate than Cobalt for such an experiment
 Impurities were seen in the BMA & PMA when tested using IR
spectroscopy
 The NMR machine is currently malfunctioning, therefore, our
samples have yet to be tested
FUTURE WORKS
 Other metals will be tested as well such as Copper (Cu2+), Lead
(Pb2+), and Mercury (Hg2+)
 The NMR machine will be finally used soon, so we can test
magnetic resonance with BMA & PMA
 A better synthesis of PMA & BMA to try to make them 100% pure
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REFERENCES
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ACKNOWLEDGEMENTS
 Mr. Edward Irwin
 Duncan Quarless, Ph. D.
 Alicia Bowen
 Dr. Sat Battacherya
 HCS Staff