The keto-enol type tautomerism in anti-thyroid drugs and their selenium analogues are described. The commonly used anti-thyroid drug methimazole exists predominantly in its thione form, whereas its selenium analogue exists in a zwitterionic form. To understand the effect of thione/thiol and selone/selenol tautomerism on the inhibition of peroxidase-catalysed reactions, we have synthesized some ...

A series of naphthaldehydes, including a Mannich base, have been investigated by UV-Vis spectroscopy, NMR and theoretical methods to explore their potential tautomerism. In the case of 4-hydroxy-1-naphthaldehyde concentration dependent deprotonation has been detected in methanol and acetonitrile. For 4-hydroxy-3-(piperidin-1-ylmethyl)-1-naphthaldehyde (a Mannich base) an intramolecular proton t...

Capillary Gas Chromatography (CGC) is capable of determining underivatized cyclophosphamide (CPA) using SCOT OV 275 columns. Then CPA is subjected to in situ degradation resulting in formation of a cyclization product which can be determined selectively in biological fluids. In routine bioanalysis however cyclization products of CPA metabolites might interfere, e.g. 4-keto CPA. In the present s...

Fapy-adenine, Fapy-guanine, Tautomerism, Solvent Effect The results of theoretical geometry prediction of formamidopyrimidine(fapy)-adenine and fapy-guanine tautomers are presented. Among 54 potential tautomeric structures of fapyadenine the most stable structure corresponds to the diamino-keto isomer. The solvent effect has insignificant influence on the fapy-adenine tautomers succession. The ...

Two new chemically stable [acid and base] 2D crystalline covalent organic frameworks (COFs) (TpPa-1 and TpPa-2) were synthesized using combined reversible and irreversible organic reactions. Syntheses of these COFs were done by the Schiff base reactions of 1,3,5-triformylphloroglucinol (Tp) with p-phenylenediamine (Pa-1) and 2,5-dimethyl-p-phenylenediamine (Pa-2), respectively, in 1:1 mesitylen...

We present a detailed CASSCF study of the mechanism of excited-state intramolecular proton transfer (ESIPT) in the o-hydroxyphenyl triazine class of photostabilizers. The valence-bond analysis of the ground state and the two pipi* excited states permits a simple chemical interpretation of the mechanistic information. Our results show that the barrier to enol-keto tautomerism on the ground-state...

Physical and coding properties of poly (5-aminouridylic acid) and of 5-aminouridine-containing trinucleotides. Crystal structure and conformation of 3-deaza-4-deoxyuridine. 5-Substituents in the uridine moiety and their effect on the conformation of ApU type dinucleoside phosphates. Restriction or amplification of wobble recognition: The structure of 2-thio-5-methylaminomethyluridine and the in...