1. The BODIPY complex is an intensely coloured, fluorescent dye that is coveted for its sharp absorption
and emission peaks, high quantum yields, redox stability, and good solubility in many solvents. While its
intense fluorescence and bioorthagonality make it an attractive candidate for biological fluorescent tag
applications, a wide range of research has invested in the use of BODIPY for dye-sensitized an organic
solar cell (DSSC) applications. Straying from the classic silicon-based photovoltaic cell, DSSC’s utilize a
donor-spacer-acceptor model which consists of electron rich donor groups and electron withdrawing
acceptors spaced by a conjugated BODIPY core. Typically, the most onerous of the accepting group due
to the consequent destabilization of the BODIPY complex. To this end, the range and scope of
nucleophilic addition is explored herein to better guide our synthetic methodologies towards acceptor
incorporation.
This poster will explore the synthesis, and will compare the optical and electronic properties of a series of
BODIPY dyes synthesized using the Wittig reaction and Schiff base formation reactions commonly used
in organic synthesis. The structure/property relationships of a series of novel dyes was studied, and
compared to the properties of their pentamethyl and formyl BODIPY predecessors using 1H-NMR and
UV-Vis spectroscopy. A comparison of the electrochemical properties of the dyes was also conducted
using cyclic voltammetry.
Exploring Nucleophilic Additions in BODIPY Derivatives and
a Study of their Optical and Electronic Properties
Sahana Sritharan, Malek El-Aooiti, Pratheesha Pathmadas, Mariya-Nikol Leshchyshyn, and Bryan D. Koivisto*
Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto ON, Canada, M5B 2K3
Chemistry and Biology Department - Fourth Annual Research Symposium - Wednesday, August 19th, 2015
Introduction
1H-NMR Cyclic Voltammetry
a Data collected using 0.1 M NBu4PF6 DCM solutions at 100 mVs−1 and referenced to a [Fc]/[Fc]+
internal standard followed by conversion to NHE; [Fc]/[Fc+] = +765 mV vs. NHE in DCM;
Summary
We would like to thank Dr. Krimo Toutah, Ben Fischer, and the
Koivisto group for the their mentorship and guidance throughout
the course of this research. Furthermore, we would like to thank
Dr. Bryan Koivisto for allowing us the opportunity to conduct this
research and for his supervision of the project.b low energy or visible transitions from UV-Vis of BODIPY family in DCM.
The addition of the vinyl ester and the Schiff bases results in the
destabilization of the BODIPY core. This makes the proton in
the 2-position particularly more susceptible to nucleophilic
attack.
(400 MHz, CDCl3, varying concentrations)
ppm
Wittig Reaction
Imine Formation
After synthesizing a series of novel Schiff-base BODIPY dyes,
and acrylic ester dye, the compounds were characterized using
NMR, UV-Vis, and CV to study the effects of the electron
withdrawing and donating groups on the electronic and optical
properties of the dyes. The presence of the ester and the Schiff
base systems resulted a notable bathochromic shift in the
absorption maxima of the dyes. Destabilization of the BODIPY
core was also observed using 1H-NMR spectroscopy. This was
determined by the downfield shift of the proton on the 2-position
resulting from the electron desheilding effects of the varying
substituents. Finally, the CV data suggest a reduced HOMO-
LUMO band gap, resulting in more efficient charge transfer.
These dyes have proved themselves to be promising candidates
for the purposes of creating next-generation photovoltaic cells.
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2
Synthetic Pathway
Imine Formation
Imine Formation
Acknowledgments
Figure 2: Superimposed UV-vis absorption spectra of BODIPY and its isolated derivatives
Compound
E1/2 (V vs NHE)a
Ered Eox
1 -1.05 1.50
2 -0.87 1.77
3 -- 1.82
4 -- --
5 -0.92 0.63
6 -- 1.93
Figure 3: Cyclic voltammogram of formyl BODIPY
Figure 1: Comparison of the desheilding of the proton on the 2-position of the various dyes
*
*
0
1
2
3
4
5
6
7
8
9
10
400 420 440 460 480 500 520 540 560 580 600
(ε×104M-1cm-1)
λ (nm)
1
2
3
4
5
6
Compound
UV-visb λmax (ε)
nm (×104 M-1cm-1)
1 497(8.3)
2 493(1.5)
3 521(5.5)
4 514(0.5)
5 517(0.9)
6 520(6.1)
UV-Vis
Note: Ignore signals
labelled with a “
*”
Donor Acceptor
π-spacer