|
Department
chemistry of complex compounds
PEKHNYO
Vasyl Ivanovych
Head of department
Corresponding Member of the Ukrainian National Academy of Sciences
Professor, Doctor of Chemistry
Deputy director in charge of scientific work of the Institute
Winner of Ukrainian State Prize in the field of science and technology.
phone: 424-25-11
e-mail: pekhnyo@ionc.kiev.ua
V.I. Pekhnyo (born in 1952) graduated with honors from the National University of
Uzhgorod in 1974. In 1974-1976, he was senior engineer at the "Tochpribor" plant,
in 1976- 1979 post-graduate student at the IGIC of the Ukrainian NAS, from 1979
till now: senior engineer, junior, senior, leading research assistant, head of
the department of the chemistry of complex compounds (since 12.01.2001), deputy
director of the IGIC of the Ukrainian NAS (03.10.2001). In 1982, he became a
Candidate of Science, since 1997 he is Doctor of Science and since 2002 Professor.
In 2003, he was elected Corresponding Member of the Ukrainian NAS.
V.I. Pekhnyo has been awarded with a certificate of honor of the Ukrainian Cabinet
of Ministers (2004) and a certificate of honor of the Ukrainian NAS (2002). Among
the authors he is a winner of Ukrainian State Prize in the field of science and
technology (1996).
V.I. Pekhnyo is the author of 273 scientific works, published in leading Ukrainian
and foreign editions, among which there are 29 inventor’s certificates and patents
for inventions and more 100 articles.
V.I. Pekhnyo is a representative of the scientific school of chemists headed by
the Member of the Ukrainian NAS Sergei Vasilyevich Volkov, which is known in CIS
and other countries.
Vasyl Ivanovych is a well-known scientist in the field of inorganic chemistry,
whose scientific achievements are associated with a very topical problem, namely
the chemistry of simple and coordination compounds of precious metals and a number
of nonferrous metals and metalloids in aqueous, nonaqueous, mixed and molten
multifunctional O-, N-, P-, S-, Se-, Te- containing solvents-reagents.
The results of studies on this subject have been presented more than once at
Ukrainian and international conferences: since 1979 at all Ukrainian conferences
on inorganic chemistry, Chugaev conferences on coordination chemistry, Chernyaev
conferences on chemistry, the analysis and technology of platinum metals, IX th
Conference on Nonaqueous Solvents (1984, Pittsburgh, USA), XXIV th Congress on
Magnetic Resonance (1988, Poznan, Poland), XII th European Conference on
Crystallography (1989, Moscow, Russia), XI th Symposium on Nuclear Quadrupole
Resonance (1991, London, Great Britain), 30 th International Conference on
Coordination Chemistry (1994, Kyoto, Japan), 36 th Congress of IUPAC (1997,
Geneva, Switzerland), European conferences on molecular melts (1998, Porqueroles,
France; 2000, Karebaksminde, Denmark), NATO Seminar on Ionic Solvents (2000, Crete,
Greece), VIII th International Conference on Crystal Chemistry (2002, Lviv,
Ukraine), II nd International Seminar on Catalysis Problems (2006, Saint-Petersburg,
Russia), XIII th International Conference on Bioinorganic Chemistry (2007, Vienna,
Austria), 38 th International Conference on Coordination Chemistry (2008,
Jerusalem, Israel), etc. V.I. Pekhnyo read scientific papers by invitations at the
Universities of Dresden, Bonn, Vienna.
The subjects of scientific research carried out under the guidance of V.I. Pekhnyo
are social and are aimed at the solution of topical problems of today:
- creation of efficient, goal-directed action low-toxicity drugs on the
basis of new synthesized precious metal compounds for the treatment of the most
common diseases: cancer, cardiovascular, virus (including HIV) diseases;
- development of waste-free methods of low energy intensity for the
comprehensive processing of mineral and secondary raw materials containing
precious metals and metalloids, which meet the present-day nature conservation
requirements;
- development of novel materials for the creation of energy-saving
and energy-converting articles.
In modern medicine, the best effect in the treatment of cancer and cardiovascular
diseases is achieved by the combination of surgical methods, radio- and
chemotherapy. The main task of chemotherapy is goal-directed delivery of
low-toxicity substrate to the disease affected organ. The task of chemists is
undoubtedly to develop methods for the synthesis of novel compounds – the basis
of drugs of the new generation which meet the above requirements.
When developing methods for the synthesis of novel coordination compounds, a
complex problem: combination of cytostatic agent (metal ion) and vehicle for
drug delivery (organic molecule - ligand) in one compound has been solved.
Low-toxicity ions of precious and other metals (Ru, Rh, Pd, Zn, Ga, Ge) and
practically nontoxic derivatives of phosphonic acids, hydrazones, salicylaldimines,
carbothioamides, etc serve these objectives; some of them are already used in
medical practice.
Modern industry and everyday life are characterized by a high level of application
of electrically powered devices, stable and long operation of which requires
ensuring certain operation conditions, such as current magnitude stability.
At the present time, multifunctional ceramics are intensively investigated to
create materials for current protection elements. Ceramic based on four component
system of the general composition
CuxNi1-x-yCo2yMn2-yO4,
which is characterized by a wide rated resistance range
(from few Ω to hundreds of kΩ) and high temperature sensitivity,
is promising in this aspect.
An especially topical problem of today is search for alternative energy sources,
one of which can be the sun. Silicon-based cells are known and used. At the same
time, chalcogenide-based cells, mainly CuInSe2-based solid solutions,
which are characterized by higher factor of conversion of solar to electrical
energy, are more promising. In recent years, scientists have been intensively
investigating the system Cu(In,Ga)(S,Se)2//Cd(S,Se) to
determine of the optimal composition which is not prone to degradation
processes.
It is in these areas that research is carried out, and good results have
been obtained by the team headed by V.I. Pekhnyo.
As a result of the works carried out, synthesis methods have been developed,
and several hundreds of new coordination compounds and substitutional solid
solutions have been synthesized, whose properties and structure have been
uniquely determined from results of vibration, electron, X-ray photoelectron,
polynuclear NMR spectroscopy, X-ray structural, elemental chemical analysis and
quantum-chemical calculations. On the basis of generation of the experimental
results obtained, new important research results have been obtained in the field
of the chemistry of precious metals in aqueous, nonaqueous, mixed solutions-reagents
and melts, the most significant of which are:
- It has been found that depending on medium pH, heating time, the concentration
and stoichiometry of the original reactants, which determine the original forms
of ligand and metal ion, mono- and binuclear complexes of cationic, anionic and
molecular type are formed in aqueous and mixed media.
- It has been proved that Ru, Rh and Pd show in the compounds under
investigation the most characteristic oxidation states +3 and +2, form
coordination polyhedra of pseudooctahedral and deformed square-planar structure
and are surrounded by donor atoms of ligand; in the case of coordinative
nonsaturation, the first coordination sphere of the central atom is complemented
by synthesis medium ligands.
- In the case of interaction between palladium salts and phosphonic acids,
the formation of complex species of anionic type, the degree of ligand
deprotonation in which depends on medium pH, has been proved; the deformed
square-planar environment in them is formed, depending on the form of original
palladium salt, by chlorine anions or ammonia molecules and a phosphonic acid
molecule coordinated in bidentate fashion by oxygen atoms or oxygen and nitrogen
atoms; the presence of conformation isomers in solutions has been substantiated
and proved experimentally (on the basis of NMR spectroscopic data).
- In the case of interaction of Ru and Rh chlorides with hydrazone derivatives,
the formation of coordination polyhedra of pseudooctahedral structure, in which
the ligand molecules are coordinated in bi- or tridentate cyclic fashion by
oxygen, sulfur, nitrogen atoms, and the functional groups (C=O), (C=S), (C-N)
and (OH) depending on synthesis conditions has been proved. The type of complex
compounds (anionic, cationic or molecular) is determined by the tautomeric form
of ligand, which depends on synthesis medium pH and the naturel of substiuents
(electron donating or electron withdrawing ones).
- In the case of interaction between platinum metal chlorides and
salicylaldimine and carbotioamide derivatives, it has been proved that
the influence of the nature of ligand on the type of the coordination
compounds formed is due to the different spatial arrangement of the
nucleophilic donor center of functional groups and to the presence of
intramolecular hydrogen bonds; increase in the number of donor centers
leads to an increase in ligand denticity, facilitates the change into another
tautomeric form and makes intramolecular rearrangement possible.
- In the case of interaction between precious metals and nonaqueous chalcogen
halides, in has been found that the form of coordinated molecules (di- or
tetrachloride form) is determined by the reaction form of metal complex
species.
- It has been proved that the chalcogen halides in the systems under
investigation are multifunctional agents; different ratio of chemically
bonded halogen and chalcogen leads to a change in their chemical activity
and influences the form and structure of the compounds formed with them by
metal ions.
- The presence in these compounds of peripheral quasi-octahedral EHal6
polyhedra with strong bond (E-Hal) of the EHal3 grouping and weak
donor-acceptor interaction between chalcogen atoms of the central
atom environment has been theoretically substantiated and experimentally
verified for the first time.
- For semiconducting ceramic of the blend composition
Cu0.1Ni0.1Co1.6Mn1.2Î4,
the main laws governing the distribution of Cu, Co, Ni, Mn and oxygen
throughout the sample volume depending on temperature, sintering and
annealing time have been established, increase in the concentration
of Cu, Co, Ni atoms and decrease in Mn and oxygen concentration in
the direction from the center to the surface of sample have been
established; at same time, the concentration of the elements is
stable at the depth of 30 ?m from the sample surface; the concentration
of Mn+4, Mn+2 and Mn+3 depends mainly on
annealing time.
- It has been proved for radiation-resistant solid solutions of
Cu(In,Ga)(S,Se)2//Cd(S,Se) chalcogenides that the change in
the efficiency of conversion of solar to electrical energy is caused by
the occurrence of a solid-phase reaction at the interface between the
constituents with the formation of an intermediate quaternary gamma phase.
The above factors determine both the chemistry of platinum metals and a number
of transition metals in aqueous, nonaqueous, mixed O-, N-, P-, S-, Se-,
Te-containing solvents-reagents and the manifestation of multifunctional
properties of the latter.
Most important practical results:
- For complexes of palladium with a number of phosphonic acids, cytotoxic
activity against Ehrlich’s carcinoma and lymphatic leukemia L 1210, which
is comparable with cisplatin ([Pt(NH3)2Cl2]) activity, but with much lower
renal and hematologic toxicity, has been established in vivo and in vitro;
selective accumulation of palladium in bones, mainly of the spinal column,
has been established, by which cytostatic delivery at the right address: to
the tumor affected bones has been demonstrated; the results obtained make it
possible to use in prospect the compounds synthesized as the basis of new
anticancer drugs.
- The selective accumulation of cytostatic (Pd ion) in bones makes it
possible to use in prospect the compounds obtained not only in the
treatment of cancer diseases of bones, but also in the localization of
metastases that arise in this region in the case of cancer diseases of
mammary and thyroid glands.
- Cardioprotective action of complex of Rh(III) with salicylaldimine
has been established; the use of this complex prevents the development
of heart reperfusion damages; it has been shown that the activation
of mitochondrial pores of cells with phenylarsenoxide suppresses cardiac
fitness, introduction of a solution of Rh(III) complex prevents
uncontrolled opening of cell pores, localizes the action of phenylarsenoxide,
which models the processes occurring in stress situations,
normalizes the action of the heart twice as quickly as in control;
the complex can be an effective for the creation of new cardioprotective drugs.
- On the basis of synthesized and investigated complexes of precious
metals with chalcogen halides, environmentally appropriate methods of
low energy intensity for the comprehensive processing of concentrates,
industrial waste and secondary raw materials containing precious metals
with practically complete recovery of all constituents of raw materials,
have been developed.
- Highly sensitive procedures for the extraction spectrophotometric
determination of a number of precious metals in the case of their joint
presence in the form of ionic associates with astraphloxine have been
developed, which can find application in practice.
- The optimal composition of Cu-, Co-, Ni- and Mn- based oxygen-containing
ceramics, the basis of the current protection elements of electrically
powered devices, has been developed, which is on a par with the best
analogs.
- The optimal composition of radiation-resistant stable-in-use solid
solutions of Cu, In, Ga, Cd chalcogenides, the basis of cells for the
conversion of solar to electrical energy, has been established, and a
technology for their production has been developed.
The scientific and technical developments of V.I. Pekhnyo have been supported
by a decision of the Presidium of the Ukrainian NAS and within the framework of
numerous works under economic agreements, grants of the Ukrainian Ministry of
Education and Science, INTAS grants, six international STCU grants. The research
has been carried out in collaboration with colleagues from institutes under the
Ukrainian NAS: V.G. Kurdyumov Institute of Metal Physics, A.A. Bogomolets
Institute of Physiology, R.Ye. Kavetskii Institute of Experimental Pathology,
Oncology and Radiobiology; Institute of the Air Force under Ukrainian Ministry
of Defence; A.V. Nikolaev Institute of Inorganic Chemistry of the Sibirian
Department of the Russian Academy of Sciences, R.Agladze Institute of Inorganic C
hemistry and Electrochemistry of the Georgian Academy of Sciences, Institute of
Inorganic Chemistry in Padova (Italy), Taras Shevchenko National University of
Kyiv, Ivan Franko National University of Lviv, Lesya Ukrayinka National University
of Volyn; foreign institutions of higher education: University of Bielefeld
(Germany), Piere and Marie Curie University of Paris (France), Massachusetts
Institute of Technology (Boston, USA); a number of Ukrainian industrial
enterprises: research-and-production enterprise "Karat" (Lviv), state enterprise
"Arsenal Plant" (Kyiv), etc.
V.I. Pekhnyo takes part in organizational and research and educational work,
supervises the work of two post-graduate students; under his guidance, 6
candidate’s theses have been defended, one these are in preparation
for defense.
Being the deputy director in charge of scientific work of the V.I.
Vernadskii Institute of General and Inorganic Chemistry of the Ukrainian NAS,
Vasyl Ivanovych is engaged in scientific and organizational work. He is a
member of the research council of the Ukrainian NAS for the problem
"Inorganic Chemistry", the specialized council for the defence of theses for a
candidate’s and doctor’s degree at the V.I. Vernadskii Institute of General
and Inorganic Chemistry of the Ukrainian NAS, the editorial board of the
"Ukrainskii Khimicheskii Zhurnal" Journal; he was a long time a member of the
expert council for chemical sciences at the Higher Certifying Commission of
Ukraine.
At the same time, Professor V.I. Pekhnyo is engaged in educational work,
heads the department of information technologies, gives a course of lectures
to the students of the State University of Mukachev.
|
|
