 Welcome to this course on Transition Metal Organometallics in Catalysis and Biology. We have been talking about all the types of applications of Transition Metal Organometallics in catalysis so far, and today we are going to move on to a very interesting topics about the Transition Metal Organometallics in Biology, and hence we would be covering the field of bio-organometallic chemistry. Now bio-organometallic chemistry can be seen in conjunction with bio-inorganic chemistry, this is bio-inorganic and bio-organometallic. We are going to be primarily focusing on bio-organometallic part, and there is a subtle distinction between bio-inorganic and bio-organometallic chemistry, and let me elucidate that before we focus on bio-organometallic aspect of the chemistry discussion. Bio-inorganic chemistry is an inter-tissue plenary field overseeing applications of metal compounds in biological biochemical worlds. So, these consist of compounds which are inorganic, organometallic and so on and so forth. So, bio-inorganic chemistry is a much broader field of applications of Transition Metal complexes, which can be inorganic as well as organometallic in applications complexes and their applications in biological and biochemical worlds, whereas the one that we will be talking about and which is not often much spoken about is bio-organometallic chemistry. Bio-organometallic chemistry is a newly evolving field that explores the utility of challenging organometallic compounds that are extremely sensitive to water. So, one aspect is that bio-organometallic chemistry explores the challenging organometallic compounds. They are challenging because they are extremely sensitive to water in biological worlds, biological and biochemical worlds of exclusive aqueous environments. So, these sort of summarize the challenges that one encounters in bio-organometallic chemistry. So, the field is a newly evolving field that looks into utility of organometallic compounds in biological and aqueous biochemical worlds of aqueous environments. And the challenge over here arises from the fact that organometallic compounds are unstable in water. So, this is a very exciting aspect of bio-organometallic chemistry and that we are going to be focusing more on bio-organometallic chemistry in this lecture the applications of bio-organometallic compounds in biological world. So, this is the focus of today's talk and nonetheless this field is evolving and growing into maturity. And the bio-organometallic chemistry has evolved in several directions and mainly I will summarize the different directions of bio-organometallic chemistry. So, this has been used for therapeutic purpose. So, this involves organometallic compounds which are used for therapy. So, that is one direction in which organometallic is currently evolving. Then the other is in bio-analysis and sensors. Also, there is considerable amount of not considerable, but notable amount of organometallic compounds in enzymes, proteins and peptides. This is what arises from the presence of organometallic compounds in biochemical world. Also, bio-organometallic chemistry in molecular recognition in aqueous making medium. This is an expanding important area of work. Last but not the least, these are also used for toxicology environment. So, what one can summarize from here is that given the fact that bio-organometallic chemistry is quite new, nonetheless the field has spread in several directions and we are going to be reviewing some of these great applications of organometallic chemistry, a bio-organometallic compounds in all of these or some of these areas. To begin with, transition metals has a wide utility in several purposes, medicinal values. I am going to present a summary of various metals and their applications. For example, silver is used for syphilis, ulcers, parasite diseases, mercury for antiseptics, antimony for this is called leishmaniasis, then copper for Menke disease, cobalt as well as a furodynamic therapy, iron, hypotension, platinum, cancer, HIV, then a bunch of metals, technetium, yttrium, gadolinium, gallium, barium, chromium, diagnostic and imaging, and strontium, radium, polonium, somerium, radiopharmaceuticals. The least sort of expand beyond to other metals, we will see, for example, gold in rheumatoid arthritis, cancer, then magnesium in hypothyroidism, then manganese photodynamic therapy, vanadium insulin mimics, then silver antibacterial studies, diagnostics and imaging, zinc, Menke disease, palladium cancer, photodynamic therapy, HIV, and lithium depression, mental health. So, what we see is that there is a great utility of various transition metal compounds, some of them inorganic, some of them organometallic in the pharmaceutical world, and they sort of have beneficial effect in treatment of wide range of diseases. Now, focusing on bioorganometallic chemistry, we are going to look into organometallic compounds of these metals, which are either existing in biological world, or they have utility as pharmaceuticals in medicinal chemistry. So, these are the two main focus that we are going to look upon during this course of this lecture. And to start with, we will talk about organometallic molecule, which is present in biological world, and this is this vitamin B12. So, vitamin B12 is an organic molecule, which is a part of vitamin, particularly one specific vitamin called methyl cobalamin, where there is a metal carbon bond present within a cobalt, within a prosthetic group containing cobalt, and this is a molecule, which is occurring naturally, and hence it is kind of wonderful to see an organometallic compound being present in a biological world, where the predominant exclusive environment medium is a aqueous medium. So, in terms of bioorganometallic chemistry, the first name which comes to mind is vitamin B12 or methyl cobalamin. So, vitamin B12 is an important water soluble vitamin involved in red blood cell production, brain health, DNA synthesis. Deficiency of vitamin B12 can cause serious symptoms, including fatigue, nerve damage, digestive issues, and neurological problems, like depression and memory loss. So, this is very important. Biodipines are molecules, body cannot create, and they are required in minor quantities, and they have to be supplied by some from the food chain. So, coenzyme B12, another form of vitamin B is called coenzyme B12, which is a cofactor form of vitamin B12. So, instead of there is another known form, which is called cyanocobalamin, is a synthetic form of vitamin B12, which is formed during the isolation. Cyanide group is bound to cobalt instead of a methyl, and that is not found in nature. So, what nature contains is this methyl cobalamin, which contains this methyl cobalt bond. So, let me just draw the structure of methyl cobalamin CONH2, and this is hydrogen CONH2 NH, methyl OH, methyl methyl, and methyl cobalt and methyl. So, there is an organometallic group, and this cobalt is coordinated to this adenosine moiety, as shown over here, and this is called methyl cobalamin. The structure was solved by Dorothy Hodgkin, in which the cyanide methyl was replaced by a cyanide group. Then there is another bioorganometallic molecule, which is known, which is shown over here. This is a coenzyme B12, and the structure of it is CONH2, CONH2, methyl, nitrogen, hydrogen, is a double bond CONH2, CONH, methyl, oxygen, OH, OH, 8, nitrogen, methyl, methyl. Here also is a methyl, which is missing, and methyl, then nitrogen, CONH2, methyl, methyl, nitrogen, this, CONH2, methyl, CONH2, and that also has a metal carbonyl bond with cobalt being bound to adenosine moiety. So, here we have two molecules, two organometallic compounds, one is methyl cobalamin, the other is coenzyme B, both containing a metal carbon bond over here, as well as over here, that are present in biological world and is very crucial. So, with this, we come to end of today's discussion, where we are exploring the various facets of organometallic chemistry, and we have looked into the utility of the field of bioorganometallic compounds in terms of medicinal purpose, as well as of their presence in biological world. And to start with, we have looked into the structure of two molecules, one is methyl cobalamin as well as coenzyme B2, B12, these are derived from vitamin B12, which are organometallic compounds found in nature, and this is supposed to be the first organometallic compound to have been discovered in natural system in a gross environment. So, with this, more on this discussion about the organometallic compounds in biology, as we continue in the next lecture. Till then, goodbye and thank you.