NAS Ukraine
Department 2

chemistry of complex compounds

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 inventors 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 Cu0.1Ni0.1Co1.6Mn1.24, 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 Ehrlichs 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 candidates 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 candidates and doctors 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.
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