4th EucheMs chemistry congress

Poster Session 1
s949
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - inorganic Chemistry
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PhotoinduCed CAtALytiC wAter reduCtion
to hydroGen By new CoBALt CoMPLexeS
BASed on tetrA- And PentAdentAte
nitroGenAte LiGAndS
A. CALL 1 , z. CodoLA 1 , M. CoStAS 1 ,
J. LLoret-fiLLoL 1
1 Universitat de Girona, Departament de Química, Girona,
Spain
Currently, one of the most appealing research areas is the
discovery and study of new electro- or photo-chemical catalysts
based on earth-abundant elements able to generate fast and
efficiently H from the reduction of water. 2 [1] Remarkable example
of electro- and photochemical water reduction catalysts has been
shown recently. [2] Nevertheless, regardless of the fast development
of the field, only few examples of well-defined, water and oxygen
robust catalysts have been developed. [3]
With this aim, we become interested in the development of
well-defined, robust and modular homogeneous catalytic systems
which their electronic and steric properties were easily tunable.
Hence, we presented a new family of catalysts for water
reduction based on iron, nickel and cobalt complexes with robust
tetra- and pentadentate nitrogenate ligands derivates from the
basic 1,4,7-triazacyclononane structure. Preliminary studies show
that not only all cobalt complexes [4] are active photo-induced
catalysts but also the H formation activity and efficiency may be
2
modulated by the electron-drawing properties of the ligand
achieving up to 420 TON in less than an hour.
In this contribution the catalytic efficiency versus the
photosensitizers used such as Ir, Ru or organic dyes and sacrificial
electron donors such as Et N, TEOA or ascorbic acid will be
3
discussed. Finally, key intermediates will the postulated based on
ongoing mechanistic studies.
references:
1. Teets, T. S. Nocera, D. G. Chem. Commun. 47, 9268-9274
(2011).
2. a) Wang, M. Na, Y. Gorlov, M. Sun, L. Dalton Trans.,
6458-6467 (2009).
b) Gärtner, F., et al. Chem. Eur. J. 17, 6425-6436 (2011).
c) Helm, M. L. et al. Science 333, 863-866 (2011).
3. a) McNamara, W. R. J. Am. Chem. Soc. 133, 15368-15371
(2011).
b) Singh, W. M. Angew. Chem. Int. Ed. 51, 1-5 (2012)
4. Artero, V. Angew. Chem. Int. Ed. 50, 7238-7266 (2011).
Keywords: water reduction; hydrogen; cobalt; water splitting;
4 th EucheMs chemistry congress
P - 0 1 7 7
reACtivity of dinuCLeAr Pt(ii) CoMPLexeS
ContAininG BidentAte n,n- And n,S-donor
LiGAndS
S. hoChreuther 1 , r. PuChtA 1 , r. vAn eLdiK 1
1 Friedrich-Alexander-University Erlangen-Nuremberg,
Department of Chemistry and Pharmacy, Erlangen, Germany
The cytostatic activity of cis-diamminedichloroplatium(II)
– cisplatin – was discovered in 1969 by Barnett Rosenberg and
this development marked a turning point in the treatment of
cancer. However, there are a number of problems that need to be
considered using cisplatin, viz. there are numerous side effects,
the anti-tumor activity is limited to certain types of cancer, and
some tumors develop a resistance during the therapy.
Besides new mononuclear complexes with improved
properties (carboplatin and oxaliplatin), a new class of
multinuclear Pt(II) complexes has been developed by Farrell and
his group. [1]
We have now synthesized a series of dinuclear Pt(II)
complexes in our group in which the two Pt(II) centers are
connected by an aliphatic chain of variable length. Furthermore,
a chelating ligand system was used that contain either exclusively
N-donor atoms (NNpy) or a mixed N- and S-donor system
(NSpy). These chelating systems stabilize the complex toward
further nucleophilic attack and inhibit the decomposition of the
dinuclear system. [2]
Cytostatic active platinum compounds react in the cell with
DNA as well as with sulfur containing substances, which leads to
loss of cytostatic activity. In our studies we focused on kinetic
measurements to examine substitution reactions with thiourea as
a strong sulfur nucleophile to gain a closer look into the reactivity
of these complexes. The rate constants of substitution can then be
compared for the two systems and amongst each other as a
function of chain length. A detailed discussion of our latest results
will be presented. [3]
references:
1. Farrell, N.; Qu, Y. Inorg. Chem. 1989, 28, 3416.
2. Hochreuther, S.; Puchta, R.; van Eldik, R. Inorg. Chem.
2011, 50, 8984
Hochreuther, S.; Puchta, R.; van Eldik, R. Inorg. Chem.
2011, 50, 12747.
3. Hochreuther, S.; van Eldik, R. Inorg. Chem.2012, 51,
3025.
Keywords: platinum; cytotoxicity; kinetics; reaction
mechanisms; ligand effects;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc