Assessing Electronically Excited States
of Cobalamins via Absorption
Spectroscopy and Time-Dependent
Density Functional Theory
Megan J. Toda, Pawel M. Kozlowski and Tadeusz Andruniów
Abstract In the field of B 12 chemistry, absorption spectroscopy, hand in hand
with computational modeling, has played an important role in describing electronically excited states of vitamin B 12 derivatives, also known as cobalamins. This
chapter focuses on the current understanding of absorption properties of cobalamins
from both spectroscopic and computational points of views. The main emphasis is
on methylcobalamin (MeCbl), adenosylcobalamin (AdoCbl), and cyanocobalamin
(CNCbl). In addition, we will discuss some other unique derivatives including antivitamins, non-alkyl cobalamins, as well as reduced and super-reduced forms. Due to
the complexity and the size of these systems, computational analysis is almost exclusively represented by density functional theory (DFT) and time-dependent DFT (TDDFT) methods. Proper DFT functional choice is paramount in predicting electronic
transitions and simulating the full spectrum reliably. At this juncture in the field of
B 12 chemistry, it is indisputable that the BP86 functional is the proper choice for the
assessment of the electronically excited states of cobalamins.
1 Introduction
Vitamin B 12 and its family of derivatives, otherwise known as cobalamins (Fig. 1),
are among the most complex organometallic naturally occurring compounds. Cobalamins contain over one hundred eighty atoms. There are certain features of these
M. J. Toda · P. M. Kozlowski
Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville,
KY 40292, USA
e-mail: megan.toda@louisville.edu
P. M. Kozlowski
e-mail: pawel.kozlowski@louisville.edu
T. Andruniów (B)
Advanced Materials Engineering and Modelling Group, Department of Chemistry,
Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27,
50-370 Wrocław, Poland
e-mail: tadeusz.andruniow@pwr.edu.pl
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_8
219
of Cobalamins via Absorption
Spectroscopy and Time-Dependent
Density Functional Theory
Megan J. Toda, Pawel M. Kozlowski and Tadeusz Andruniów
Abstract In the field of B 12 chemistry, absorption spectroscopy, hand in hand
with computational modeling, has played an important role in describing electronically excited states of vitamin B 12 derivatives, also known as cobalamins. This
chapter focuses on the current understanding of absorption properties of cobalamins
from both spectroscopic and computational points of views. The main emphasis is
on methylcobalamin (MeCbl), adenosylcobalamin (AdoCbl), and cyanocobalamin
(CNCbl). In addition, we will discuss some other unique derivatives including antivitamins, non-alkyl cobalamins, as well as reduced and super-reduced forms. Due to
the complexity and the size of these systems, computational analysis is almost exclusively represented by density functional theory (DFT) and time-dependent DFT (TDDFT) methods. Proper DFT functional choice is paramount in predicting electronic
transitions and simulating the full spectrum reliably. At this juncture in the field of
B 12 chemistry, it is indisputable that the BP86 functional is the proper choice for the
assessment of the electronically excited states of cobalamins.
1 Introduction
Vitamin B 12 and its family of derivatives, otherwise known as cobalamins (Fig. 1),
are among the most complex organometallic naturally occurring compounds. Cobalamins contain over one hundred eighty atoms. There are certain features of these
M. J. Toda · P. M. Kozlowski
Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville,
KY 40292, USA
e-mail: megan.toda@louisville.edu
P. M. Kozlowski
e-mail: pawel.kozlowski@louisville.edu
T. Andruniów (B)
Advanced Materials Engineering and Modelling Group, Department of Chemistry,
Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27,
50-370 Wrocław, Poland
e-mail: tadeusz.andruniow@pwr.edu.pl
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_8
219