A coordination compound is any substance in which a metal is a central atom and is surrounded by multiple nonmetal atoms or groups of atoms (ligands). Coordination compounds are synthesized through Lewis acid-base reactions and feature distinctive physical and chemical properties. From metallurgy and pigment production to biology and medicine, coordination compounds are widely used in numerous industrial and scientific areas. Here are ten reasons why coordination complexes are so crucial:
#1. Hemoglobin Carries Oxygen to the Tissues
Hemoglobin is a metalloprotein with iron as a central metal atom, making it a coordination compound. This protein is found in red blood cells and is responsible for delivering oxygen to the tissues. Iron enables hemoglobin to pick oxygen molecules up as we breathe the air and carry them to tissues throughout the body. Since hemoglobin consists of four iron-containing subunits, each hemoglobin molecule is capable of transporting four oxygen molecules.
#2. Chlorophyll Enables Plants to Obtain Energy from the Sun during Photosynthesis
Chlorophyll is a magnesium-containing coordination compound in which magnesium is right in the center of the modified porphyrin ring. Chlorophyll is an essential complex that plays a crucial role in photosynthesis, during which chlorophyll molecules absorb sunlight and store it in forms of energy. Plants then use this energy to convert carbon dioxide and water into glucose. In order for chlorophyll to facilitate the photosynthetic process, magnesium ions stabilize the chlorophyll molecules and keep the electrons in an excited state to transfer them down an electron transport chain.
#3. Vitamin B12 Is the Only Vitamin Containing a Metal Ion
Vitamin B12, also referred to as cobalamin, is a cobalt-containing coordination complex. This water-soluble vitamin is involved in many vital processes, such as red blood cell and DNA formation, the development and proper functioning of brain and nerve cells, and many more. When taken as a supplement, Vitamin B12 can promote metabolism and help patients with digestive problems.
#4. Many Enzymes Are Coordination Compounds
Enzymes are proteins that act as biological catalysts and increase the rate of literally every chemical reaction occurring in our cells. The enzymes found in our body enable us to perform vital tasks, such as metabolism and respiration. As a matter of fact, many enzymes are coordination compounds, and therefore, are commonly known as metalloenzymes. Some common metalloenzymes include carbonic anhydrase, nitrogenase, superoxide dismutase, hydrogenase, Vitamin B12-dependent enzymes, and chlorophyll-containing enzymes.
#5. Coordination Compounds Are Used as Anti-Cancer Drugs
Metal-based coordination compounds have been widely used to treat cancer. Two of the most common heavy metal-containing chemotherapy drugs are carboplatin and cisplatin. These are coordination complexes containing platinum. While carboplatin is an alkylating agent and is typically used to treat ovarian cancer, cisplatin is best known for being able to treat testicular cancer. Still, both coordination complexes are used for curing a wide range of cancers, including but not limited to lung, cervical, and bladder cancers.
#6. Coordination Compounds Are Involved in the Treatment of Patients Poisoned with Heavy Metal Ions
Heavy metal poisoning is often caused by heavy metals such as arsenic, cadmium, chromium, lead, and mercury. Prolonged exposure to heavy metals can permanently damage your organs or increase the risk of cancer. Understanding how coordination compounds work allows healthcare professionals to treat heavy metal poisoning. BAL (British Anti-Lewisite) and EDTA (ethylenediamine tetraacetic acid) are two chemicals used for treating arsenic and lead poisoning, respectively. The consumption of both leads to the production of coordination compounds.
#7. Coordination Complexes Are Used in X-Ray Crystallography and Nuclear Magnetic Resonance
Hexaamminecobalt (III) chloride is the chloride salt of the cobalt-containing coordination compound. The complex is widely used in X-ray crystallography and NMR, allowing scientists to solve the structure of DNA and RNA molecules. In these structural biology methods, hexaamminecobalt (III) chloride stabilizes the tertiary structure of the backbone consisting of alternating sugar and phosphate groups.
#8. Coordination Compounds Are Used as Dyes and Pigments
Coordination compounds have been used as dyes and pigments from ancient times. For example, the ancient Greeks used a metal-containing hydroxyanthraquinone complex as a red dye called madder dye. Besides, copper phthalocyanine, also known as phthalocyanine, is a bright blue pigment widely used in industrial coatings, textile, and paper production. In addition, metal complexes of azo compounds are also commonly used as dyes and pigments.
#9. Coordination Compounds Are Helpful for Quantitative and Qualitative Analysis
Coordination complexes are widely used in different branches of analytical chemistry. Some of the common analytical techniques involving the use of coordination compounds are titrimetric analysis, gravimetric analysis, liquid-liquid extraction, and multiple types of chromatography. Besides, many chemicals used during quantitative and qualitative analysis (e.g., EDTA) function by producing colored metal complexes. So, whether directly or not, coordination compounds play an important role in numerous analytical methods.
#10. Coordination Compounds Are Involved in Metallurgy
Metallurgy is a process through which metals are extracted in their pure form. On the other hand, hydrometallurgy is a branch of metallurgy that involves the use of aqueous media to obtain metals from ores and waste materials. Coordination compounds are widely used in metallurgy and hydrometallurgy. For instance, these complexes are useful for the extraction of nickel and cobalt. This is because the metal ions present in the coordination compounds grant them unique abilities to selectively dissolve and precipitate metals.