Transcript (1) and New York University (2)

Molecular Recognition by PicolylamineBased Tripodal Ligands and Its Application
in Sensing and Asymmetric Catalysis
Amanda Mickley,1 Patrick Carney,1 Steven Lopez,2
Jennifer Lee,2 and Zhaohua Dai1,*
Chemistry Departments of Pace University (1) and New York University (2)
Objective
• Improve the selectivity in the detection of Hg(II) through a
stereochemical approach which systematically employs
chiral podand, piperidine bearing ligands sulfur atoms;
• Improve Hg(II) sensing sensitivity by using circularly
polarized fluorescence excitation (CPE);
• Systematically develope Fe(II) complexes of TPA-based
chiral podands, piperidines and quinuclidines as green
asymmetric catalysts for better product control and
prediction in alkane hydroxylation by H2O2. Elucidate its
mechanism
• Elucidate mechanism to facilitate the better understanding
of the interactions operating the above-mentioned
molecular recognition events
Chiroptical Fluorescence Sensors for Mercury
1st Genearation Sensor for Mercury
Ratiometric Fluorescent Sensor
Hg2+
Chiroptical Response
HgII
CuII
CH3
Pattern Recognition:
Signal Selectivity
Hg2+
O
S
HO
N
N
-1
N
Next Generation Sensors for Hg2+
O
HO
O
S
HO
N
N
HOOC
N
O
O
COOH
1
OH
O
O
OH
O
O
HOOC
OH
COOH
N
S
HO
N
Zn
0
1
2
3
2+
Total Zn (M)
0
-5
H
200 220 240 260 280 300 320 340
(n m )
2
+ (R,R)-2
-5
-10
-15
-20
Zn
-25
N
H
5
lysozyme
0
2+
F (V)
10
O
5
18
16
14
12
10
8
6
4
2
0
F307 (V)
d 15
F (V)
O
We intend to use these ligands
to further develop circularly
polarized fluorescence
excitation (CPE), which is
based on fluorescence-detected
circular dichroism, which gives
better contrast and eliminates
many spectral interferences.
(c)
2+
-30
200 220 240 260 280 300 320 340
 (nm)
I
O
S
O
O
+
N
O
N
N
AcO
O
OAc
O
S
O
N
N
N
O
O
O
O
O
hydrolysis
1.
O
O
O
O
O
O
O
Exact Mass: 1221.30
Molecular Weight: 1222.23
O
O
Alkane Hydroxylation
R1
Chiral-TPA Fe(II) Complexes
R1
*
CH2
R2
CH
H2O2
OH
R2
• Converting saturated C-H bonds directly into
alcohols
• Important to synthetic organic chemistry, fuel
industry and other industries using petrochemical
feed stock
• Helpful in modeling electron-transfer processes in
biological systems, and producing new catalysts
Fe(II)-TPA as Catalysts
Ligands: Achiral; Complexes: Octahedral
K. Chen and L. Que, Jr, JACS, 2001, 123, 6327
Products: Regio-selective, Diastereo-selective
•Not enantio-selective
Rigidification Enhances Enantiomeric
and Regional Selectivity
M. S. Chen, M. C. White. Science, 2007, 318, 783.
Our Approach
Make Chiral Ligands and use their Fe-(II) complexes as
catalysts
N
N
Systematically rigidify the chiral ligand to improve
enantio- and regio- selectivity
N
N
Put Br on ligands to increase reactivity according DFT
calculation
N
N
N
H
N
H
H
Chiral podand
N
N
H
N
H
N
N
piperidine
N
N
H
H
N
H
quinuclidine
Podand and Piperidine Ligands
Br
Br
N
N
N
N
H
H
C21H20Br2N4
Exact Mass: 486.01
Synthesis of Quinuclidines
HC COOC2H5
CH
+ H2C
H2C COOC2H5
COOC2H5
O
1) HCl, reflux
C2H5OH + Na
oxalyl chloride
HC CH2 C OH
COOC2H5
o
2) 190 C
3
Br
N
CH3NHOCH3
O
HC CH2 C Cl
O
Br
O
Li
CH3
HC CH2 C
HC CH2 C N
3
OCH3
3
3
Br
Br
Br
(+)DIP-Cl
Br
N
HC CH2 CH
3
OH
NH3
N
MsCl
HC CH2 CH
N
OMs
Br
N
N
H
N
H
N
o
3
50 C
H
29
SSS-29
Br
Br
Br
N
N
H
N
H
N
H
C22H19Br3N4
m/e: 577.91 (100.0%),
579.91 (97.6%), 575.92
(34.3%), 581.91 (31.9%),
SSS-29 Purity and Cu(II) Complex
Acknowledgement
• Prof. James Canary (NYU)
• Prof. Demosthenese Athanasoupolos (Pace)
• Kirill Grinberg (Midwood High School)
Funding:
ACS Petroleum Research Fund
Research Corporation for Science Advancement
Pace University Scholarly Research Fund
Pace University Kenan Faculty Development Fund