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 ×

10

4 M

-1 c

m-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