As a common structural unit in secondary metabolites of organisms, nitrogen compounds widely exist in nature. Because of their unique physiological and pharmacological activities, high endogenicity and low toxicity, nitrogen compounds are often used as structural units in medicine and agriculture, and have been widely applied in medicine, herbicides, pesticides, fungicides, etc. Among the nitrogen compounds, the number of nitrogen compounds containing thiazole ring, pyridine compounds, indoles compounds and piperidone compounds is especially large, and a large number of new compounds are synthesized every year. Many nitrogen compounds including thiazole, pyrazole, pyrimidine, piperidine, pyridine and indoles have been widely used in medicine synthesis.
Due to the special biological activity of materials containing thiazole in nature, thiazole and its derivatives can not only relieve pain and inflammation, but also be used as fungicides, as well as anti-parasite, anti-tuberculosis, anti-rheumatism and anti-cancer. Nitrogen compounds containing pyridine rings are widely used in the synthesis of drugs for the treatment of cardiovascular and cerebrovascular diseases, allergies, psychosis and AIDS.
Medicine: Nitrogen compounds have played an essential role in the process of drug development. From the epochal penicillin to the present fourth generation cephalomycin, the human health benefits a lot from nitrogen compounds. In addition, nitrogen compounds also exist in the antihypertensive drug (Reseipine), the pyrimidine antagonists with antitumor activity, synthetic analgesics, barbiturates and sedatives.
Fig. 1 Synthesis of Piribedil for the treatment of Parkinson’s disease (Journal of American Chemical Society 2009, 1766-1774)
Organic pigment: The development of nitrogen compounds has laid a solid foundation for the development of pigments. Since the development of organic pigments, the continuous expansion of the application field has put forward new and higher requirements for the products of organic pigments. For example, the cyclic amide group was introduced into azo pigment, and the high-grade benzimidazolone azo pigment was produced by increasing the polarity of pigment molecules, which increased the water-solubility of the pigment.
Pesticide: In terms of pesticides, nitrogen compounds have emerged and gradually become the mainstream of new pesticides research and development. There are fungicides, herbicides and many super-efficient pesticides containing nitrogen compounds. The ultra-high efficiency of nitrogen compound pesticide not only reduces the cost, but also minimizes the environmental impact. Moreover, most of the new pesticides containing nitrogen compounds have little toxicity to warm-blooded animals like birds and animals.
Dye-sensitized solar cell: The complex of nitrogen compound and ruthenium in dye-sensitised solar cells has been more and more widely used owing to its advantages. The complexes possess special chemical stability, good excited state reactivity, long life of excited states, high quantum yield and excellent luminous performance.
Fig. 2 Synthesis of pyridyl-based dyes for solar cells (Dalton Transactions 2008, 6940-6947)