Polymorphism: Meaning, Types, Applications and Importance

Crystals are solid materials in which the constituent atoms are arranged in a fixed pattern and its regular surface framework portrays its internal symmetry. The basic units of solids are atoms or atoms that have combined into molecules. Crystals are called solids at all temperatures below their melting point.

In chemistry, polymorphism is a condition when a solid chemical substance exhibits more than one crystalline form. Crystalline substances can be characterised and distinguished based on the unit cell structure. The crystal’s forms may vary physically and sometimes in chemical properties, but the solutions are identical.

Let’s see the different types of polymorphism, applications of polymorphism, and the relation between isomorphism and polymorphism.

Polymorphism

Polymorphism is a state in which a solid chemical compound exists in more than a single crystalline form. At times, the forms differ in physical and chemical properties, even though their solutions and vapours are identical.

The word ‘polymorphism’ comes from the Greek roots ‘poly’ (many) and ‘morphe’ (form). Eilhardt Mitscherlich, a German scientist, observed differences in the crystalline forms of numerous elements and compounds in the 1820s. It gained more application scope in the 21st century after extensive drug research started.

Now that we know what is polymorphism and its origin, let’s study different types of polymorphism. There are different types of polymorphism, namely: Mono-Tropic Polymorphism and Enantiotropic Polymorphism.

Also, read about Organic Chemistry here.

Types of Polymorphism

Different types of polymorphism can be classified into two main categories based on the stability of the solid crystals when exposed to a range of factors like temperature, pressure, etc.

• Monotropic Polymorphism: Monotropic polymorphism is a process in which one polymorph, among others, stays stable at every temperature range.
• Enantiotropic Polymorphism: Unlike monotropic polymorphism, the polymorphs of enantiotropic polymorphism exhibit different stabilities. Some polymorphs may be stable at low temperature, whereas others can be stable at the high-temperature range, and vice versa.

Study about the Development of Periodic Table here

Relation between Isomorphism and Polymorphism

Isomorphism and polymorphism differ in many aspects. Polymorphism is the existence of a compound in more than one crystalline form, while Isomorphism is the existence of two or more compounds having the same morphology.

The key difference between polymorphism and isomorphism is that isomorphism can be defined as the presence of the same morphology in various substances, while polymorphism is the presence of different morphologies of the same substance.

Isomorphism is absent in elements while polymorphism is present in elements. Isomorphous substances have identical shapes while polymorphous substances have different shapes.

Study more about Emulsions & Suspensions here.

Importance of Polymorphism

Polymorphism is highly important in the pharmaceutical industry and for the development of medicinal drugs. Bioavailability and solubility are important aspects of drug delivery and polymorphism affect both of them.

The structure of a solid crystal is essential to determine how effective a drug is and the effects it can have on the human body. Due to variations in the solubility of polymorphs, one polymorph may be therapeutically more successful than another polymorph of a similar product. In several areas, a particular drug receives regulatory approval for only one of its polymorphs. So, we can say that polymorphism is vital in the field of medicine.

Learn more about Solutions here.

Polymorphism Applications

Polymorphism has several applications and can also be found in day-to-day activities. Here are some applications of polymorphism:

• An example of polymorphism that most people encounter daily is common salt (sodium chloride), which is used for food preparations. Sodium chloride exists in the shape of cubes or needles. The cube can be extracted from seawater, while the needles cannot be separated from seawater as they are too large to dissolve. The different shapes follow the property of entropy, where more energy is added to disordered sodium and chlorine atoms, and they take up a more structured order.
• Many scientists have tried to implement polymorphism in drug creation that would best fit a particular patient’s needs. Polymorphic differences exist between people and their ability to metabolise medications, causing some to react adversely. The importance of polymorphism in this is that it could potentially target the issues by being able to take on different forms and treat a wider range of symptoms or disorders better than conventional medications.
• Polymorphism is also seen in agrochemicals such as malathion. They also find usage as a control agent. It is also used in pharmaceuticals such as salicylic acid and cholesterol-lowering drugs, commercial dyes and pigments, including phthalocyanine green (blue).

In this article, we have discussed in detail polymorphism and its various applications in the real world. Visit the Testbook website where you can find multiple courses on various subjects for free. Download the Testbook App from the google play store and take advantage of this opportunity now.