Determination of ionization constants by spectrophotometry

Albert, Adrien; Serjeant, E. P.

doi:10.1007/978-94-009-5548-6_4

Cited by 60 publications

(57 citation statements)

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“…These values are higher than that of the 5-propynylated 2'-deoxyuridine 1a (14.92). The pK a -value changes were also noticeable; they were determined UV-spectrophotometrically [33] (from pH 1.5 to 11.50) at 220 -350 nm. The 5-alkynyl-2'-deoxyuridines showed the following pK a values: 8.7 for 1b and 8.8 for 1c.…”

mentioning

confidence: 97%

Nucleosides and Oligonucleotides with Diynyl Side Chains: Base Pairing and Functionalization of 2′‐Deoxyuridine Derivatives by the Copper(I)‐Catalyzed AlkyneAzide ‘Click’ Cycloaddition

Seela

Sirivolu

2007

Helvetica Chimica Acta

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Oligonucleotides containing the 5‐substituted 2′‐deoxyuridines 1b or 1d bearing side chains with terminal CC bonds are described, and their duplex stability is compared with oligonucleotides containing the 5‐alkynyl compounds 1a or 1c with only one nonterminal CC bond in the side chain. For this, 5‐iodo‐2′‐deoxyuridine (3) and diynes or alkynes were employed as starting materials in the Sonogashira cross‐coupling reaction (Scheme 1). Phosphoramidites 2b–d were prepared (Scheme 3) and used as building blocks in solid‐phase synthesis. Tm Measurements demonstrated that DNA duplexes containing the octa‐1,7‐diynyl side chain or a diprop‐2‐ynyl ether residue, i.e., containing 1b or 1d, are more stable than those containing only one triple bond, i.e., 1a or 1c (Table 3). The diyne‐modified nucleosides were employed in further functionalization reactions by using the protocol of the CuI‐catalyzed Huisgen–Meldal–Sharpless [2+3] cycloaddition (‘click chemistry’) (Scheme 2). An aliphatic azide, i. e., 3′‐azido‐3′‐deoxythymidine (AZT; 4), as well as the aromatic azido compound 5 were linked to the terminal alkyne group resulting in 1H‐1,2,3‐triazole‐modified derivatives 6 and 7, respectively (Scheme 2), of which 6 forms a stable duplex DNA (Table 3). The Husigen–Meldal–Sharpless cycloaddition was also performed with oligonucleotides (Schemes 4 and 5).

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mentioning

confidence: 97%

Nucleosides and Oligonucleotides with Diynyl Side Chains: Base Pairing and Functionalization of 2′‐Deoxyuridine Derivatives by the Copper(I)‐Catalyzed AlkyneAzide ‘Click’ Cycloaddition

Seela

Sirivolu

2007

Helvetica Chimica Acta

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“…6, No. 3;2014 27 The pKa values for Schiff bases (1-3) and their yellow orange isomers were determined (Albert et al, 1974) successfully by potentiometric titration method. Results collected in this investigation were tabulated in Table 4.…”

Section: Methodsmentioning

confidence: 99%

Determination of Structures for Some Syn and Anti Isomeric Anil Schiff Bases by Some Spectroscopic and Physical Methods

Azzouz¹,

Hyali²

2014

IJC

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Originally, three aromatic anil Schiff bases were synthesized by reactions of salicylaldehyde with o-,m-and p-phenylene diamine by a standard method, in the presence of azeotrope forming solvent. Two syn and anti isomeric Schiff bases having yellow and orange colors were separated by fractional recrystalization in ethanol, when primary aromatic amine used having o and p-phenylene diamine structures. Mean while m-phenylene diamine gave a single yellow anti isomeric compound.The main aim of the study was the determination of structures for these five syn and anti Schiff base isomers by the available physical methods. These were performed by using melting points, UV-IR spectra and pKa values for these amphiprotic substances. Results collected in this investigation were interpreted and discussed by proper scientific way depending on experimental data collected.

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“…The pH-dependent absorption spectra show the presence of isosbestic point. The pK a values have been evaluated from the absorbance vs. pH data by the general method of Albert and Sergeant [22] using eq 3 where, Abs Ψ , Abs HOx and Abs Ox represent the absorbance of partially ionized, unionized and completely ionized form of oxime respectively at particular pH.…”

Section: Determination Of Acid Dissociation Constant (Pk a ) By Albermentioning

confidence: 99%

Acid Dissociation Constants and Molecular Descriptors of Some Xylene Linked Bispyridinium Oximes

Singh¹,

Soukup²,

Doležal³

et al. 2015

MMSL

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SummaryThe present article is aimed at determination of acid dissociation constants (pK a ), lipophilicity (logP) and hydrogen bond acceptor (HBA) and donor (HBD) counts of some novel xylene-linked bispyridiniumoxime based AChE reactivators. The choice was supported by their use in the therapy of acute intoxication with organophosphorus AChE inhibitors. UV-Vis spectrophotometry has been used to measure experimental pK a values at 27°C, while software Marvin Sketch (chemaxon) has been used to estimate structure based computational pK a , logP values and hydrogen bonding parameters. The results were compared with standard oximes (HI-6 and obidoxime) under similar conditions. All the calculated pK a values lie in the range of 7.45-9.85 which is well in agreement with most of the oxime reactivators studied so far.

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Determination of ionization constants by spectrophotometry

Cited by 60 publications

References 0 publications

Nucleosides and Oligonucleotides with Diynyl Side Chains: Base Pairing and Functionalization of 2′‐Deoxyuridine Derivatives by the Copper(I)‐Catalyzed AlkyneAzide ‘Click’ Cycloaddition

Nucleosides and Oligonucleotides with Diynyl Side Chains: Base Pairing and Functionalization of 2′‐Deoxyuridine Derivatives by the Copper(I)‐Catalyzed AlkyneAzide ‘Click’ Cycloaddition

Determination of Structures for Some Syn and Anti Isomeric Anil Schiff Bases by Some Spectroscopic and Physical Methods

Acid Dissociation Constants and Molecular Descriptors of Some Xylene Linked Bispyridinium Oximes

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