Thesis Research Proposal
By: Rubenier Montano-Serrano
Mentor: Raphael G. Raptis
The increasing global population requires energy alternatives to non-renewable sources
that we are using today. Although solar energy is being used widely, in many developed
countries it hasn’t reached the expectations needed to solve the energy demands of today and the
near future. Photovoltaic is the field of technology and research related to the application of solar
cells for energy by converting sunlight directly into electricity. We propose the synthesis of
artificial antennas to improve the efficiency of photovoltaic cells. The cells we know today are
mainly made of transparent semiconducting oxides like SiO2, but the most advanced technology
does not pass the 10% of electricity conversion from sunlight. To solve this problem a new area
of research in photovoltaic cells focuses in Organic Photovoltaic Cells that mimic natural
antennas and obtain better conversion efficiencies. These molecular devices absorb light and
generate electrons to create a charge separation state in order to produce current. To produce this
state we need an electron donor and an electron acceptor.
There are many examples of electron donors like porphyrins, oligothiphenes, and
carotenes. But the insufficiency of good electron acceptors has moved the research for the almost
exclusive use of fullerenes. Fullerenes are good electron acceptors but require more energy than
the donors can reach in order for the fullerenes to accept a second electron.1 Also fullerenes have
an inconvenient lack of solubility; this extremely affects the uniformity of photovoltaic cells.
We propose the use of Fe8(μ4-O)4(μ-pz*)12Cl4 which has been demonstrated to be a very
good electron acceptor. 2 This molecular cluster can accept up to four electrons, but the most
important point to note here is the low energy needed to reduce the cluster: Two electrons are
accepted at an energy lower than that needed for the fullerene to accept the first electron. We
predict that more than one electron can be accepted using the available electron donors. This step
has never before been achieved in the photovoltaic cells research. If we improve the accepting
capacity we will be able to generate more current and therefore increase the efficiency of the
conversion from sunlight to electricity. Controlling and designing these molecular devices is part
of the fourth generation of Nanotechnology. Preparing these nanosystems is relevant for the
advancement of the science and for development of sustainable energy generation. Functional
nanomaterials research is needed to consider solar energy as a good alternative for daylight
working hours, but we also need to store enough energy to use it at nighttime.
Batteries are a good option, while the storage of H2 from hydrolysis driven by solar
energy is another option. We receive daily more energy from sunlight that the global demand of
one year. 3 Like natural antennas we suggest the artificial preparation of a photosynthetic center
that can produce H2 by hydrolysis. Within the photosynthesis a chain of electron transfer events
take place, leading to charge separation. The charge imbalance created becomes the motor that
powers the synthesis of ATP. Mimicking this process using porphyrins as sunlight traps to excite
electrons, we can generate an artificial charge separation device. The components of this antenna
could be an oligothiophene or a carotene which will act as the electron donor, coupled to a
porphyrin which absorbs sunlight and generates the electrons, and the Fe8 cluster that we are
suggesting as the electron acceptor. This system is called a triad and the charge separation will
look like: Donor +⋅ - Chromophore – Acceptor -⋅ (Scheme 1).
The Fe8 cluster is an inorganic complex surrounded by pyrazolate ligands that provide the
functional groups which impart solubility in diverse organic solvents, contrary to fullerenes.
Using pyrazolates we have the flexibility to change a functional group at the fourth position in
order to vary the way to link the complex to donor molecules. Pyrazoles with an aldehyde or an
amine in the fourth position can react to make an amide covalent bond. Examples of these
reactions exist for some triads in literature. 4,5 Another alternative is the use of pyridinylpyrazole
to attach the cluster noncovalently to a porphyrin center. 6 We have already worked on the
preparation of substituted pyrazole ligands and characterization of Fe8(μ4-O)4(μ-pz)12Cl4.
We are proposing our plans for the next year to be the synthesis a characterization of the
electron acceptor molecule. During the next semester we are going to synthesize an Fe cluster
using FeCl3 as starting material with the desired substituted pyrazoles and characterize the
resulting inorganic complex (Scheme 2). Although X-ray crystallography will be the best
analytical option to determine the structure, we can also use other spectroscopic techniques like
Elemental Analysis, IR, UV-Vis and NMR. The focus for the second semester will be the
understanding of the electrochemistry of the cluster and finding the appropriate electron donor
molecule to attach to our complex.
Scheme 2. 8 FeCl3 + 24 R-pzH + 20 Et3N → Fe8(μ4-O)4(μ-R-pz)12Cl4
Where R can be CHO-, NH2- or C5NH5-.
Guo, F.; Ogawa. K.; Kim, Y.G.; Danilov, E.O.; Castellano, F.N.; Reynolds, J.R.; Schanze, K.S. Phys. Chem. Phys.
2007, 9, 2724-2734.
Baran, P.; Boca, R.; Chakraborty, I.; Giapintzakis, J.; Herchel, R.; Huang, Q.; McGrady, J.E.; Raptis, R.G.;
Sanakis, Y. and Simopoulos, A. Inorg. Chem. 2008, 47, 645-655.
Morton, O. Nature 2006, 443, 19-22
Kanato, H.; Narutaki, M.; Takimiya, K.; Otsubo, T.; Harima, Y. Chem. Lett. 2006, 35, 668-669.
Kuciauskas, D.; Lidell, P.A.; Hung, S.C.; Lin, S.; Stone, S.; Seely, G.R.; Moore, A.L.; Moore, T.A.; Gust, D. J.
Phys. Chem. B 1997, 101, 429-440.
Kira, A.; Tomokazu, U.; Matano, Y.; Yoshida, K.; Isoda, S.; Park, J.K.; Kim, D.; Imahori, H. J. Am. Chem. Soc.
2009, xxx, 000.
List of Publications and Presentations
By: Rubenier Montano-Serrano
1. Research Letters in Nanotechnology Vol. 2009, Article ID 971423, 5 pages: “Nanostructural
Formation of Pd-Co Bimetallic Complex on HOPG Surfaces: A XPS and AFM Study” by Lisandra
Arroyo-Ramírez, Rubenier Montano-Serrano, Raphael Raptis and Carlos R. Cabrera
2. Nanotech 2007, vol.4, chapter 2. Nanoparticles pages 385-386:
“The use of Molecular Precursors for the Preparation of Pd/Co-Alloy Nanoparticles” by
R. Montano-Serrano, C. Moiras and R.G. Raptis
1. XXXII Senior Technical Meeting of the ACS, Rincón, PR November 21, 2008: SEGQuim:
Enhancing the Academic Experience in Chemistry Graduate School
2. AAAS Caribbean Division Scientific Meeting, October 4, 2008 Río Piedras, PR: Molecular
Precursors for Preparing Pd/Co and Pd/Cu-Alloy Nanoparticles
3. Latin American Federation of Chemical Associations (FLAQ) 28th Latin American Chemical
Congress San Juan, PR July 27-August 1, 2008: The use of Molecular Precursors for the Preparation
of Pd/Co and Pd/Cu-Alloy Nanoparticles
4. ACS 235th National Meeting & Exposition New Orleans, LO April, 2008: The use of Molecular
Precursors for the Preparation of Pd/Co and Pd/Cu-Alloy Nanoparticles
5. 28st Puerto Rico Interdisciplinary Scientific Meeting (PRISM) 43st Junior Technical Meeting
Arecibo, PR March 8, 2008: The use of Molecular Precursors for the Preparation of Pd/Co and
1. Nano Science and Technology Institute (NSTI) Nanotech Santa Clara, CA May 20-24, 2007: The
use of Molecular Precursors for the Preparation of Pd/Co-Alloy Nanoparticles
2. WAESO Tempe, AZ April 2007: The use of Molecular Precursors for the Preparation of Pd/Co-
1. XXX Senior Technical Meeting of the ACS, Dorado, PR November 3-4, 2006:
Pd2Co(4-Br-Me2pz)4Cl4.2 Et3NH and Co2Pd(4-Br-Me2pz)4Cl4 .2 Et3NH Molecular Precursors for
2. AAAS Caribbean Division Scientific Meeting, October 28, 2006 Bayamón, PR: The use of
Pd2Co(4-Br-Me2pz)4Cl4 and Co2Pd(4-Br-Me2pz)4Cl4 Molecular Precursors for the Preparation of
3. Second Transdisciplinary Research Conference Mayaguez, PR May 5, 2006: Heterobimetallic
Molecular Precursors and studies of CoPd2(Me2Ipz)4Cl4 Nanoparticles on HOPG
4. 26st Puerto Rico Interdisciplinary Scientific Meeting (PRISM) 41st Junior Technical Meeting
Cayey, PR March 11, 2006: Synthesis of Molecular Precursors for Metallic Nanoparticles
1. AAAS Caribbean Division Bayamón, PR December, 2005: Molecular Precursors of Metallic
2. XXIX Senior Technical Meeting of the ACS, Lajas, PR November 4, 2005: Molecular Precursors
of Metallic Nanoparticles
1. ACS 233th National Meeting & Exposition Chicago, IL March, 2007: The use of Molecular
Precursors for the Preparation of Pd/Co-Alloy Nanoparticles