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Substituent

About: Substituent is a research topic. Over the lifetime, 42877 publications have been published within this topic receiving 516716 citations. The topic is also known as: side chain & side group.


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Journal ArticleDOI
TL;DR: A previously introduced nomenclature for leukotrienes is extended on the basis of the nature of the cysteine substituent and the total number of double bonds in new and earlier described compounds.

147 citations

PatentDOI
TL;DR: In this paper, a liquid crystal material which at least contains a compound having a molecular structure such that the material exhibits a liquid-crystal phase, the molecular structure of the compound being selected from one of the following structures: the structure, a simple ortho-substituted derivative of the structure, and a derivative in which a simple bridging group is contained between two of the orthopositions of the said structure wherein X and Y are different parasubstituents of the kind which promote liquid crystal behaviour.
Abstract: OF THE DISCLOSURE A liquid crystal material which at least contains a compound having a molecular structure such that the material exhibits a liquid crystal phase, the molecular structure of the compound being selected from one of the following structures: the structure ; a simple ortho-substituted derivative of the structure ; and a derivative of the structure in which a simple bridging group is contained between two of the ortho-positions of the said structure wherein X and Y are different para-substituents of the kind which promote liquid crystal behaviour, the para-substituent X being a group selected from the following list: an alkoxy group having more than one carbon atom; an alkyl group; an acyloxy group; and an alkenyl group; and the para-substituent Y being selected from the following list: a cyano group; a benzene ring substituted in the para-position by a cyano group; and a plurality of directly para-linked benzene rings in which the end ring remote from the substituent X is substituted in the para-position by a cyano group. The material may be the said compound or it may be a multi-component solution or mixture containing it. The liquid crystal material may be nematic, smectic or cholesteric depending on the selection of the substituents X and Y. A device such as a twisted nematic effect device, incorporating the material may be operated at low temperatures. The material does not suffer from significant chemical and/or photochemical decomposition when used in a liquid crystal device.

146 citations

Journal ArticleDOI
TL;DR: Analyses of the individual atom-atom pair radial distribution functions, and in particular those for C···Cl(-), have revealed that hydrogen bonding to the first methylene or methyl units of the substituent groups is important.
Abstract: A detailed investigation of hydrogen bonding in the pure ionic liquids [C4C1im]Cl and [C2C1im]Cl has been carried out using primarily molecular dynamics techniques. Analyses of the individual atom–atom pair radial distribution functions, and in particular those for C···Cl–, have revealed that hydrogen bonding to the first methylene or methyl units of the substituent groups is important. Multiple geometric criteria for defining a hydrogen bond have been applied, and in particular the choice of the cutoff angle has been carefully examined. The interpretation of hydrogen bonding within these ionic liquids is highly angle dependent, and justification is provided for why it may be appropriate to employ a wider angle criteria than the 30° used for water or alcohol systems. The different types of hydrogen bond formed are characterized, and “top” conformations where the Cl anion resides above (or below) the imidazolium ring are investigated. The number of hydrogen bonds undertaken by each hydrogen atom (and the c...

146 citations

Journal ArticleDOI
TL;DR: In this paper, a series of salicylideneaniline (SA) derivatives 1 and 2 were prepared to study the substituent effect on the chromic properties.
Abstract: A series of salicylideneaniline ( SA ) derivatives 1–3 were prepared to study the substituent effect on the chromic properties. Compounds 1 and 3 , introduced naphthyl group on the A ring in the parent compound SA , exhibited the solvatochromism, thermochromism and photochromism, while compound 2 , introduced the naphthyl group on the B ring in SA , did not show the solvatochromism or thermochromism. The discussion in this study is mainly focused on the behaviour of compounds 1 and 2 . The UV absorption spectra of 1 dramatically changed with increasing the solvent polarity as well as cooling temperature, suggesting that 1 takes Z -NH form in polar solvents at room temperature or even in non-polar solvents at below 120 K. Compound 1 emits fluorescence (FL) only at low temperature with small Stokes shift, while 2 exhibits fluorescence emission with considerably large Stokes shift. On UV irradiation, 1 in benzene underwent intramolecular hydrogen atom transfer to give E -NH form. The large Stokes shift observed in 2 indicates that 2 takes E -OH form even at low temperature in any solvents, and underwent intramolecular hydrogen atom transfer in the excited state to give Z -NH form, which emits the fluorescence at low temperature, or undergoes isomerization around CC double bond to give E -NH form. The potential energy diagrams for 1 and 2 were also determined.

146 citations

Patent
10 Dec 1979
TL;DR: In this article, the formulae for anti-hypertensives are defined, and the substituent is a carboxyalkyl dipeptide derivatives and related compounds.
Abstract: Carboxyalkyl dipeptide derivatives and related compounds which are useful as antihypertensives, and having the formulae: wherein R and R 6 are the same or different and are hydroxy, alkoxy, alkenoxy, dialkylamino alkoxy, acylamino alkoxy, acyloxy alkoxy, aryloxy, alkyloxy, substituted aryloxy or substituted aralkoxy wherein the substituent is methyl, halo, or niethoxy, amino, alkylamino, dialkylamino, aralkylamino or hydroxyamino; R 1 is hydrogen, alkyl of from 1 to 20 carbon atoms, including branched, cyclic and unsaturated alkyl groups; substituted alkyl wherein the substituent is halo, hydroxy, alkoxy, aryloxy amino, alkylamino, dialkylamino, acylamino, arylamino, guanidino, imidazolyl, indolyl, mercapto, alkylthio, arylthio, carboxy, carboxamido, carbalkoxy, phenyl, substituted phenyl wherein the substituent is alkyl, alkoxy or halo; aralkyl or heteroaralkyl, aralkenyl or heteroaralkenyl, substituted aralkyl, substituted heteroaralkyl, substituted aralkenyl or substituted hetereoaralkenyl, wherein the substituent is halo or dihalo, alkyl, hydroxy, alkoxy, amino, aminomethyl, acylamino, dialkylamino, alkylamino, carboxyl, haloalkyl, cyano or sulfonamido, aralkyl or hetereoaralkyl substituted on the alkyl portion by amino or acylamino; R 2 and R 7 are hydrogen or alkyl; R 3 is hydrogen, alkyl, phenylalkyl, aminomethylphenyl- alkyl, hydroxyphenylalkyl, hydroxyalkyl, acetylaminoalkyl, acylaminoalkyl, acylaminoalkyl aminoalkyl, dimethyl- aminoalkyl, haloalkyl, guanidinoalkyl, imidazolylalkyl, indolylalkyl, mercaptoalkyl and aikylthioalkyl; R 4 is hydrogen or alkyl; R 5 is hydrogen, alkyl, phenyl, phenylalkyl, hydroxyphenylalkyl, hydroxyalkyl, aminoalkyl, guanidinoalkyl, imidazolylalkyl, indolylalkyl, mercaptoalkyl or alkylthioalkyl; R and R 5 may be connected together to form an alkylene bridge of from 2 to 4 carbon atoms, an alkylene bridge of from 2 to 3 carbon atoms and one sulphur atom, an alkylene bridge of from 3 to 4 carbon atoms containing a double bond or an alkylene bridge as above, substituted with hydroxy, alkoxy or alkyl and the pharmaceutically acceptable salts thereof.

146 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023660
20221,273
2021568
2020787
2019753
2018858