The Catalyst Review May 2024 - 3

Independent Perspective
The views expressed are those of the individual author and may not reflect those of The Catalyst Review or TCGR.
To expand on The Catalyst Review's Breakthrough Announcement in February, featuring Dr. Gregory Arzoumanidis
and his team's latest development in Artificial Photosynthesis, Dr. Michail Paraskevas joins Dr. Arzoumanidis to
provide additional context.
Artificial Photosynthesis - A Novel Approach
By Michail Paraskevas and Gregory G. Arzoumanidis*
Titanium Oxy-dichloride (TiOCl2
natural photosynthesis. Direct capturing of atmospheric CO2
and H2
)/2-phenyl indole complexes - a " living " chemical system energized by visible light emulating
and H2
mechanism based on a cascade of self-organized organotitanium intermediates.
We report herein an unprecedented self-organized chemical " living " system emulating natural photosynthesis, featuring direct
atmospheric capturing (DAC) of CO2
(Titanium Oxydichloride) or PI/Ti(OH)2
Cl2
complexes, reacting with CO2
O (humidity) under ambient temperature and pressure, with subsequent autonomous CO2
reduction with H2O protons to long-chain aliphatic oxygenated products. This system originates from easily accessible 2-phenyl indole
(PI) complexes with TiCl4, at PI/TiCl4 molar ratios of 2:1, 1:1, and 1:2, energized by visible light, after hydrolysis by air humidity to the
corresponding PI/TiOCl2
All three types of PI/TiCl4
complexes give similar results. The 2:1 complex is preferred and was selected for detailed study.
The porous, air-exposed 2PI.TiCl4 powder operates independently, dynamically and unceasingly over a period of several weeks,
energized by visible light, constantly absorbing H2O and CO2 from the air, while simultaneously undergoing color changes from dark
brown to khaki and green. Besides hydrolysis and DAC of CO2
, the system operates as a cascade of several additional continuous,
intertwined, but essentially independent processes:
* Visible light photocatalytic reduction of TiIV
to TiIII and TiII. Formation of peroxotitanium complexes, with enhanced
photoabsorption in the visible range. Photocatalytic water oxidation, N-oxidation of the PI ligand.
* Reduction of the organotitanium carbonates (captured CO2
) to CO, H2CO and CH3
hydrogen transfer from atmospheric water. Photocatalytic coupling of H2
* Subsequent construction of oxygenated organic compounds with linear carbon chains, C2
system-generated formaldehyde as the building block.
* PI ligand exchange with donor molecules THF, formaldehyde. Adducts formation with H2
Their formal participation in the visible light photo-catalytic process.
CO and CH3OH to form HOCH2
to C7
O, HCl, HOCH2
* PI photocatalytic oligomerization.
These spontaneous cascade processes were monitored by Maldi-Tof spectra, supported by proton and 13
OH coordination complexes, with
CH2
OH.
and beyond, using
CH2
OH.
to generate organotitanium carbonates.
O, generating linear long-chain organic products. Proposed
C NMR, along with IR spectra.
The elucidated structures of several process intermediates constitute supporting evidence for understanding the modus operandi for the
entire photocatalytic system.
Verification and identification of over thirty coordination compounds generated by the system, primarily organotitanium intermediates
designated in sequential groups, and other organic products like a PI continuum of oligomers, provide supporting evidence of proposed
individual mechanisms within the overall process. Currently, the system may be regarded as a primary model, or the prototype for
new applications using related structural assemblies (molecular machines), anticipating delivery of improved outcomes. Analogous
systems incorporating other metals (Zr, Hf, V), photoactive monodentate or polydentate ligands as substitutes of PI, other halides and
pseudohalides, are obvious choices.
TCGR has not independently verified or duplicated these results. *Dr. Arzoumanidis looks forward to receiving feedback from readers,
ideally with their own investigation efforts. He can be reached at arzoumandis@gmail.com.
Your Authors
Dr. Michail Paraskevas is a third-generation chemist.
He received his BSc in 2002 from the University of
Parma (Italy), his MSc in 2006 from the National and
Kapodistrian University of Athens (Greece) and his
PhD in 2013 from the National Technical University
of Athens (Greece). His field of expertise covers
organic and catalysis to inorganic/organometallic and
analytical chemistry. Since 2009, he has worked as
an R&D Scientific Advisor on several projects regarding reinforcement
of thermoplastics with CNTs and TiO2
nanoparticles and graphene
synthesis. He joined the Guangdong Technion Israel Institute of
Technology in 2019 as a Lecturer and Lab Manager.
The Catalyst Review
Gregory Arzoumanidis, Chem. Diploma Aristotle
U. Thessaloniki, Greece; PhD U. Stuttgart,
Germany; Postdoc MIT; MBA UConn; has been an
industrial Research Chemist with expertise in olefin
polymerization catalysis, development of new industrial
organic and inorganic catalytic processes (aniline,
anthraquinone, hypophosphorous acid) and scale-up/
commercialization of polypropylene catalysts. With over 50 years of
experience in organotitanium/-zirconium chemistry, he is now proposing
new Ti/Zr complexes for cancer therapy and as photocatalysts in artificial
photosynthesis. Email: arzoumandis@gmail.com.
May 2024
3

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