Metal complexes as catalysts and ferments in various chemical and biological processes

Chemistry in Moldova had a special start through the research of coordinative compounds. This research has created a foundation for the development of inorganic, organic, physicochemical, analytical, ecological and quantum chemistry. This branch of chemistry has become the engine of chemical research in the Republic of Moldova and has placed the country at the forefront of many countries in this field.

Chemistry has become one of the three main fields, along with physics and materials science, which have brought prestige to the scientific community of the Republic of Moldova. The positioning of Moldova on the 38th place in the world ranking of sciences is a remarkable achievement.

However, it should be noted that unfortunately, the reforms in the scientific system have negatively affected research in Moldova. Although the chemistry of coordination compounds continues to maintain the level of research, sustained action is required to avoid rapid degradation. It is essential to get involved in the management of science and to pay special attention in order not to lose the history of science in Moldova.

It is important to promote investment in research, encourage international collaboration and provide support to researchers. These measures could contribute to the maintenance and continuous development of the chemistry of coordination compounds and other scientific fields in the Republic of Moldova.

 Here are some of the scientists who received the Nobel Prize for their contributions to the chemistry of coordination compounds and the chemistry of enzymes:

Alfred Werner (1866-1919): awarded the Nobel Prize in Chemistry in 1913 for his development of the theory of coordination compounds and his contributions to the development of chemistry.

Henry Taube (1915-2005): awarded the Nobel Prize in Chemistry in 1983 for his work on electron transfer reactions in coordination compounds.

 Eduard Buchner (1860-1917): awarded the Nobel Prize in Chemistry in 1907 for his discovery that fermentation can take place outside of living organisms, thus developing the foundations of enzyme chemistry.

 Daniel Shechtman (b. 1941): awarded the Nobel Prize in Chemistry in 2011 for his discovery of quasicristals, which have relevance in understanding the structure and functioning of some enzymes.

 Chemists from Romania  who contributed to the development of the chemistry of coordinative compounds:

Gheorghe Spacu (1883-1985): a prominent Romanian chemist known for his work in coordination chemistry and the chemistry of transition metal complexes. He obtained about 1000 new complex combinations, which enriched the coordinative chemistry.

Marius Andruh (n.1954): a renowned Romanian chemist who has made important contributions to the understanding of metal-ligand interactions and the design of new coordination compounds.

Chemists from the Republic of Moldova who contributed to the development of the chemistry of coordinative compounds

Anton Ablov (1905-1968) - the founder of the Scientific School in the field of chemistry of coordination compounds in the Republic of Moldova. Scientific concerns have been focused on the study of the effect of trans interaction in the class of cobalt(III) dioximates.

Nicolae Gărbălău (1931-2006) - the founder of the Scientific School in the Field of Chemistry of Coordination compounds, macrocyclic and supramolecular compounds. Through his research, he contributed to the development of new methods – the templar synthesis of topochemical reactions.

 The metal coordination complexes play a crucial role in chemistry, science, and society. These compounds are formed when a central metal ion or atom is surrounded by a group of ligands, which are typically molecules or ions that donate electrons to the metal ion. The metal coordination complex is formed through coordination bonds, which are typically formed through the donation of electron pairs from the ligands to the metal ion.

The metal coordination complexes are of great importance in biochemistry due to their involvement in a wide range of biological processes. In biological systems, coordination complexes often consist of metal ions coordinated to specific ligands, which play crucial roles in various biochemical reactions and functions.

Let's explore each of these roles in more detail:

Metal Complexes as Catalysts ["Catalysis by Metal Complexes"/ Piet W. N. M. van Leeuwen/ Wiley-VCH/ 2005, 317 p.]

 Some common examples of metal complexes used as catalysts include:

a. Transition Metal Complexes ["Transition Metal Complexes"/ F. Albert Cotton/, Journal Accounts of Chemical Research, 1975, Vol. 8, nr 11, Pag. 379-386].

Transition metals such as platinum, palladium, and ruthenium are commonly used in catalysis. For instance, platinum complexes are used as catalysts in fuel cells for the oxidation of hydrogen, while palladium complexes are employed in cross-coupling reactions.

b. Homogeneous Catalysis [ “Homogeneous Catalysis with Metal Complexes: Fundamentals and Applications / Gheorghe Duca/ Springer/2012, 478p.]

Metal complexes can act as homogeneous catalysts, where the catalyst is in the same phase as the reactants. They can coordinate with reactant molecules and undergo reversible coordination and ligand exchange processes, thereby facilitating the desired chemical transformations.

c. Heterogeneous Catalysis ["Heterogeneous Catalysis: Principles and Applications"/Jens K. Nørskov, Felix Studt, Frank Abild-Pedersen, and Thomas Bligaard / Springer/ 2014, 400p.].

 Metal complexes can also be immobilized on solid supports, creating heterogeneous catalysts. These catalysts are widely used in industrial processes. For example, transition metal complexes supported on solid materials like zeolites or metal oxides can catalyze important reactions such as hydrogenation and oxidation.

d. Quantum chemistry [“Modern Quantum Chemistry: Introduction to Advanced Electronic Structure Theory”/Attila Szabo, Neil S.Ostlund/ Mineola, New York, 1996, 461p.]

It provides a theoretical framework to predict the behavior of metal complexes. provides a powerful set of tools for understanding the electronic structure, bonding and reactivity of metal complexes. It enables to predict the properties of metal complexes,facilitating the design of catalysts and new functional materials.

 e. Metal Complexes as Ferments (Enzyme Mimics): ["Metal Complexes as Artificial Enzymes for Catalyzing Nucleic Acid Reactions"/ Yan Zhao and Weihong Tan/ Journal Accounts of Chemical Research/ 2011, Vol.44, nr.12, pag. 1356-1366].

In recent years, metal complexes have gained attention as enzyme mimics or artificial enzymes. These complexes can replicate some of the functions of natural enzymes, which are biological catalysts. The advantages of metal complex catalysts over enzymes include stability, synthetic tunability, and ease of synthesis. Some examples of metal complexes functioning as enzyme mimics include:

 a. Metalloporphyrins:   ["Metalloporphyrins in Catalytic Oxidations"/ Zeev Gross and A. Ghosh/Wiley/2000, 325p.]

Metalloporphyrins, particularly those containing iron or manganese, are widely studied as enzyme mimics due to their ability to perform redox reactions and oxygen activation. They can mimic the functions of heme-containing enzymes like cytochrome P450.

 b. Metalloenzymes: [ "Metalloenzymes in Denitrification: Applications and Environmental Impacts"/ Claudio A. Bonomo, Esteban A. Dell'Acqua, and Lina Giannuzzi/Springer/ 2016, 235p.].

Metal complexes can be designed to mimic the active sites of metalloenzymes, such as metallohydrolases and metalloproteinases. These complexes can catalyze a variety of reactions, including hydrolysis, oxidation, and reduction.

 c. Biomimetic Catalysis: "Biomimetic Catalysis: From Understanding to Application"/Gerard Roelfes and Gerard van Koten/Wiley-VCH/2011, 524p.

Metal complexes can be tailored to mimic specific enzymatic reactions, such as DNA cleavage, biomolecule recognition, and asymmetric catalysis. These biomimetic catalysts offer a synthetic approach to perform complex transformations found in nature.

Metal complexes as catalysts and ferments have found applications in various fields, including pharmaceuticals, chemical synthesis, energy conversion, and environmental remediation. Their versatility and tunability make them valuable tools for designing efficient and selective catalysts, as well as for gaining insight into enzymatic processes.

President of the Chemical Society of Republic of Moldova, 

Acad. Prof. Gheorghe DUCA