Different Schiff Bases—Structure, Importance and Classification

Abstract

Schiff bases are a vast group of compounds characterized by the presence of a double bond linking carbon and nitrogen atoms, the versatility of which is generated in the many ways to combine a variety of alkyl or aryl substituents. Compounds of this type are both found in nature and synthesized in the laboratory. For years, Schiff bases have been greatly inspiring to many chemists and biochemists. In this article, we attempt to present a new take on this group of compounds, underlining of the importance of various types of Schiff bases. Among the different types of compounds that can be classified as Schiff bases, we chose hydrazides, dihydrazides, hydrazones and mixed derivatives such as hydrazide–hydrazones. For these compounds, we presented the elements of their structure that allow them to be classified as Schiff bases. While hydrazones are typical examples of Schiff bases, including hydrazides among them may be surprising for some. In their case, this is possible due to the amide-iminol tautomerism. The carbon–nitrogen double bond present in the iminol tautomer is a typical element found in Schiff bases. In addition to the characteristics of the structure of these selected derivatives, and sometimes their classification, we presented selected literature items which, in our opinion, represent their importance in various fields well.

A study of the photochemical behaviour and relaxation mechanisms of anti–syn isomerisation around quinazolinone –N–N bonds

“…17 Their properties of chemical and biological signicance [18][19][20] can be attributed to the presence of the double bond (N]C or N]N), oen acting as a linkage between aromatic systems. 21,22 Schiff bases have applications in many elds, 23 e.g. pharmacology, 24,25 medicine, 26 catalysis, 27 dyes 28,29 and photoswitching materials.…”

Some Aromatic Schiff Bases and Their Metal Complexes

“…Nowadays, one of the greatest imperatives is the synthesis and characterization of new drugs with enhanced activity and safer application [1]. One of the promising groups of compounds in this field is undoubtedly Schiff bases and their metal complexes, due to the ease of synthesis, interesting coordination properties, and wide range of possible applications [2][3][4]. Research has shown that aromatic carbonyl compounds form stable Schiff bases, while those with aliphatic compounds are prone to polymerization.…”

Photofunctions in Hybrid Systems of Schiff Base Metal Complexes and Metal or Semiconductor (Nano)Materials

“…There are many original papers, as well as excellent reviews on the current state of knowledge in chemistry of such compounds concerning their synthesis methods, crystal structure and useful properties including bioactive, magnetic, catalytic, electrochemical and photoluminescent ones [ 10 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. The current review focuses on very interesting photofunctions observed in hybrid systems built of Schiff base metal complexes and various materials, such as metal or semiconductor nanoparticles, as well as polymer matrices.…”