Pub Date : 2018-07-18DOI: 10.5772/INTECHOPEN.76986
S. Pal
Pyridine (C 5 H 5 N) is being the simplest six-membered heterocycles, closely resembles its structure to benzene. The “N” in benzene ring has its high electronegativity influence on resonance environment and produces markedly different chemistry from its carbon ana - log. The presence of nitrogen and its lone pair in an aromatic environment makes pyri dine a unique substance in chemistry. The sp 2 lone pair orbital of “N,” directed outward the ring skeleton, is well directed to have overlap with vacant metal orbital in producing an σ bonding interaction. This causes pyridine to be a ligand and has been utilized with all transition metals in producing the array of metal complexes. A rich literature of metal complexes is now available with pyridine and its derivatives. Innumerable complexes have been synthesized with academic as well as industrial importance. To shed a light on ligating capability of pyridine, transition metal complexes with pyridine, and its deriva tive is presented in this chapter.
{"title":"Pyridine: A Useful Ligand in Transition Metal Complexes","authors":"S. Pal","doi":"10.5772/INTECHOPEN.76986","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.76986","url":null,"abstract":"Pyridine (C 5 H 5 N) is being the simplest six-membered heterocycles, closely resembles its structure to benzene. The “N” in benzene ring has its high electronegativity influence on resonance environment and produces markedly different chemistry from its carbon ana - log. The presence of nitrogen and its lone pair in an aromatic environment makes pyri dine a unique substance in chemistry. The sp 2 lone pair orbital of “N,” directed outward the ring skeleton, is well directed to have overlap with vacant metal orbital in producing an σ bonding interaction. This causes pyridine to be a ligand and has been utilized with all transition metals in producing the array of metal complexes. A rich literature of metal complexes is now available with pyridine and its derivatives. Innumerable complexes have been synthesized with academic as well as industrial importance. To shed a light on ligating capability of pyridine, transition metal complexes with pyridine, and its deriva tive is presented in this chapter.","PeriodicalId":20827,"journal":{"name":"Pyridine","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84178866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-18DOI: 10.5772/INTECHOPEN.77969
P. Pandey
Pyridine (C5H5N), an aromatic compound where all the pi electrons are shared by a ring, forms one continuous circle of electrons besides the alternate double bonds shared by every atom on the circle. Pyridine is a unique type with nitrogen on the ring to provide a tertiary amine by undergoing reactions such as alkylation and oxidation. Amine is responsible for the slight dipole on the ring because electrons are drawn more toward the nitrogen being electronegative (lone pair electrons on the nitrogen) than other atoms in the ring. The H nuclear magnetic radiation (H-NMR) shows three signals at the ortho, meta, and para positions on the molecule in respect of three different chemical shifts. These chemical shifts are the result of the different electron densities for each of these atoms. As a result, this is not stable as other aromatic compounds (Figure 1).
{"title":"Introductory Chapter: Pyridine","authors":"P. Pandey","doi":"10.5772/INTECHOPEN.77969","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.77969","url":null,"abstract":"Pyridine (C5H5N), an aromatic compound where all the pi electrons are shared by a ring, forms one continuous circle of electrons besides the alternate double bonds shared by every atom on the circle. Pyridine is a unique type with nitrogen on the ring to provide a tertiary amine by undergoing reactions such as alkylation and oxidation. Amine is responsible for the slight dipole on the ring because electrons are drawn more toward the nitrogen being electronegative (lone pair electrons on the nitrogen) than other atoms in the ring. The H nuclear magnetic radiation (H-NMR) shows three signals at the ortho, meta, and para positions on the molecule in respect of three different chemical shifts. These chemical shifts are the result of the different electron densities for each of these atoms. As a result, this is not stable as other aromatic compounds (Figure 1).","PeriodicalId":20827,"journal":{"name":"Pyridine","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83818527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-18DOI: 10.5772/INTECHOPEN.74719
Y. Hamada
Pyridine is a unique aromatic ring. Although pyridines are used industrially, pyridine moieties are present in many natural products, such as vitamins, coenzymes, and alkaloids, and also in many drugs and pesticides. Pyridine moieties are often used in drugs because of their characteristics such as basicity, water solubility, stability, and hydrogen bond-forming ability, and their small molecular size. Because pyridine rings are able to act as the bioisosteres of amines, amides, heterocyclic rings containing nitrogen atoms, and benzene rings, their replacement by pyridine moieties is important in drug discovery. Recently, we synthesized a series of BACE1 inhibitors by in silico conformational structure-based drug design and found an important role of pyridine moiety as a scaffold. In this chapter, we describe the important role of pyridines in medicinal chemistry and the development of β-secretase inhibitors possessing a pyridine scaffold for the treatment of Alzheimer’s disease.
{"title":"Role of Pyridines in Medicinal Chemistry and Design of BACE1 Inhibitors Possessing a Pyridine Scaffold","authors":"Y. Hamada","doi":"10.5772/INTECHOPEN.74719","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.74719","url":null,"abstract":"Pyridine is a unique aromatic ring. Although pyridines are used industrially, pyridine moieties are present in many natural products, such as vitamins, coenzymes, and alkaloids, and also in many drugs and pesticides. Pyridine moieties are often used in drugs because of their characteristics such as basicity, water solubility, stability, and hydrogen bond-forming ability, and their small molecular size. Because pyridine rings are able to act as the bioisosteres of amines, amides, heterocyclic rings containing nitrogen atoms, and benzene rings, their replacement by pyridine moieties is important in drug discovery. Recently, we synthesized a series of BACE1 inhibitors by in silico conformational structure-based drug design and found an important role of pyridine moiety as a scaffold. In this chapter, we describe the important role of pyridines in medicinal chemistry and the development of β-secretase inhibitors possessing a pyridine scaffold for the treatment of Alzheimer’s disease.","PeriodicalId":20827,"journal":{"name":"Pyridine","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86613962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-18DOI: 10.5772/INTECHOPEN.75636
S. Satoh
This chapter describes our recent findings on diverse biological effects of pyridinecarbox - ylic acids, both pyridine- di -carboxylic acids (PDCAs) and pyridine- mono -carboxylic acids (PCAs), on plant growth processes. PDCA analogs promoted flowering and extended dis - play time (vase life) of cut flowers of spray-type carnation. 2,3-PDCA and 2,4-PDCA were most active in the promotion. Apart from these actions, some of PDCAs and PCAs stimu - lated root and shoot growth of lettuce, carrot, and rice seedlings. Studies on structure– activity relationship of the chemicals showed that one of the most effective chemicals was pyridine-3-carboxylic acid. Pyridine-3-carboxylic acid is known as vitamin B3 (niacin) and safe for human and animals. These findings suggested the possibility to develop PDCAs and PCAs as novel flower-care agents as well as growth-promoting agents which will be used for vegetable cultivation. inhibited it in lettuce, carrot, and rice seedlings. We explored the promoting activities of 2,3-PDCA to other PDCA analogs and pyridine-mono-carboxylic acid (PCA) analogs. Also, we carried out a preliminary investigation on the possible biochemical and molecular mechanism of PDCA, mainly with 2,4-PDCA. This chapter describes the details of the effects of 2,4-PDCA and related chemicals on flower opening and display time in carna tion flowers, as well as the promotion of seedling growth in some agricultural crops. GA GA GA 3 in petals of opening flowers Os 2 reached Os 4–6 in 4 days in the control flowers. treatment accelerated flower opening, and all the treated flowers reached Os 4–6 in 2 days. We measured GA 3 content in the non-treated flowers at days 0–4 and found that the GA 3 level tended to be decreased in the course of flower opening. We also measured GA 3 content in 2,4-PDCA-treated flowers at day 1, when the treated flowers showed a significant increase in the number of open flowers. We observed a tendency that GA 3 content in the 2,4-PDCA-treated flowers was lower than that in the control. The GA 3 content in the control flowers was 48.5 ± 10.0 pmol·g −1 FW, whereas it was 26.6 ± 14.3 pmol·g −1 FW in the 2,4-PDCA-treated flowers. There was no significant difference between the control and the treated samples by t -test at P < 0.05. These results showed 2,4-PDCA increases the gene expression of the growth suppressor, GAI, and decreases the GA level, suggesting that GA signaling and action are altered by 2,4-PDCA treatment. such changes are contradictory to the enhancement of flower opening, which that 2,4-PDCA
{"title":"Diverse Promotive Action of Pyridinecarboxylic Acids on Flowering in Ornamentals and Seedling Growth in Vegetable Crops","authors":"S. Satoh","doi":"10.5772/INTECHOPEN.75636","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.75636","url":null,"abstract":"This chapter describes our recent findings on diverse biological effects of pyridinecarbox - ylic acids, both pyridine- di -carboxylic acids (PDCAs) and pyridine- mono -carboxylic acids (PCAs), on plant growth processes. PDCA analogs promoted flowering and extended dis - play time (vase life) of cut flowers of spray-type carnation. 2,3-PDCA and 2,4-PDCA were most active in the promotion. Apart from these actions, some of PDCAs and PCAs stimu - lated root and shoot growth of lettuce, carrot, and rice seedlings. Studies on structure– activity relationship of the chemicals showed that one of the most effective chemicals was pyridine-3-carboxylic acid. Pyridine-3-carboxylic acid is known as vitamin B3 (niacin) and safe for human and animals. These findings suggested the possibility to develop PDCAs and PCAs as novel flower-care agents as well as growth-promoting agents which will be used for vegetable cultivation. inhibited it in lettuce, carrot, and rice seedlings. We explored the promoting activities of 2,3-PDCA to other PDCA analogs and pyridine-mono-carboxylic acid (PCA) analogs. Also, we carried out a preliminary investigation on the possible biochemical and molecular mechanism of PDCA, mainly with 2,4-PDCA. This chapter describes the details of the effects of 2,4-PDCA and related chemicals on flower opening and display time in carna tion flowers, as well as the promotion of seedling growth in some agricultural crops. GA GA GA 3 in petals of opening flowers Os 2 reached Os 4–6 in 4 days in the control flowers. treatment accelerated flower opening, and all the treated flowers reached Os 4–6 in 2 days. We measured GA 3 content in the non-treated flowers at days 0–4 and found that the GA 3 level tended to be decreased in the course of flower opening. We also measured GA 3 content in 2,4-PDCA-treated flowers at day 1, when the treated flowers showed a significant increase in the number of open flowers. We observed a tendency that GA 3 content in the 2,4-PDCA-treated flowers was lower than that in the control. The GA 3 content in the control flowers was 48.5 ± 10.0 pmol·g −1 FW, whereas it was 26.6 ± 14.3 pmol·g −1 FW in the 2,4-PDCA-treated flowers. There was no significant difference between the control and the treated samples by t -test at P < 0.05. These results showed 2,4-PDCA increases the gene expression of the growth suppressor, GAI, and decreases the GA level, suggesting that GA signaling and action are altered by 2,4-PDCA treatment. such changes are contradictory to the enhancement of flower opening, which that 2,4-PDCA","PeriodicalId":20827,"journal":{"name":"Pyridine","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86538807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-18DOI: 10.5772/INTECHOPEN.75046
A. A. A. Hamid
Owing to the growing interest and unique properties of pyridines as bases, effects of sub - stitution and substituent modification on electron density enrichment of the pyridyl nitro gen, and thus the effectiveness of pyridine as metal ion-stabilizers will be introduced in this chapter. Pyridines of the structure C 5 (S)nH 5 -nN (S = substituent) that have been inten - sively studied theoretically were selected as examples to prove the concept of this chapter. Computational results in the reviewed reports showed that: substitution and substituent modification significantly affect the electronic enrichment of nitrogen atom of the pyridine. The conclusions extracted from the covered investigations were employed to promote pyri - dines to act as efficient stabilizers for the coordinated metal ions. In coordination chemistry, these kinds of coordinated complexes are highly demanded in the field of chemosensation.
由于吡啶作为碱的兴趣和独特的性质，取代和取代基修饰对吡啶基氮电子密度富集的影响，以及吡啶作为金属离子稳定剂的有效性将在本章中介绍。本文选取了理论上研究较多的结构为c5 (S) nh5 - nn (S =取代基)的吡啶作为例子来证明本章的概念。综述报告的计算结果表明:取代和取代基修饰对吡啶氮原子的电子富集有显著影响。从所涵盖的研究中提取的结论被用来促进吡啶作为有效的稳定剂的配合金属离子。在配位化学中，这类配位配合物在化学感觉领域有很高的需求。
{"title":"Substituent Effect on Pyridine Efficacy as a Chelating Stabilizer","authors":"A. A. A. Hamid","doi":"10.5772/INTECHOPEN.75046","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.75046","url":null,"abstract":"Owing to the growing interest and unique properties of pyridines as bases, effects of sub - stitution and substituent modification on electron density enrichment of the pyridyl nitro gen, and thus the effectiveness of pyridine as metal ion-stabilizers will be introduced in this chapter. Pyridines of the structure C 5 (S)nH 5 -nN (S = substituent) that have been inten - sively studied theoretically were selected as examples to prove the concept of this chapter. Computational results in the reviewed reports showed that: substitution and substituent modification significantly affect the electronic enrichment of nitrogen atom of the pyridine. The conclusions extracted from the covered investigations were employed to promote pyri - dines to act as efficient stabilizers for the coordinated metal ions. In coordination chemistry, these kinds of coordinated complexes are highly demanded in the field of chemosensation.","PeriodicalId":20827,"journal":{"name":"Pyridine","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87986722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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