Synthesis of new double (spin and fluorescence) sensor reagents and labels

Abstract

Dedicated to Prof. András Lipták on the occasion of his 70th birthday.New double (spin and fluorescence) sensors were synthesized from aminocoumarin, pyrene and 4-nitrobenzofurazan dyes and from five-or six-membered nitroxides or their diamagnetic derivatives with aromatic nucleophylic substitution, Suzuki cross-coupling reaction and acylation reactions. The new compounds exhibit fluorescence emission between 382-529 nm affording various utilization possibilities. Introduction.Fluorescent probes and sensors have attracted attention because of their high sensitivity and an exceptional ease of handling relative to their radioactive counterparts [1]. Connection of a fluorophore with a nitroxide free radical or its sterically hindered amine precursor results in a double (fluorescent and spin) sensor reagent, based on a nitroxide free radical (as an acceptor) fluorescence emission quenching of a fluorophore (as a donor) and the mechanism of the quenching has been well-documented in several cases [2,3]. The redox-status of the nitroxide or its amine precursor has a great influence on fluorescence emission intensity and this idea was utilized in design of new double sensor reagents. These reagents can be used in analytical chemistry to detect Reactive Oxygen Species (ROS) by electron spin resonance spectroscopy (EPR) and by fluorescence spectroscopy [4,5] or fluorophore attached nitroxides can be utilized as redox-indicators [6]. In our laboratory several new type donoracceptor pairs have been synthesized based on dansyl [7], aminophthalimide [8], benzazole [9] and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) [10] type fluorophores. Till now, the most successful one has been the 3-[N-(β-diethylaminoethyl)-N-dansyl] aminomethyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrole, so-called "DanePy", which is widely used in the singlet oxygen detection in plant physiology under oxidative stress conditions [11]. Another challenge in this area is the synthesis of doublelabel molecules combining advantages of the fluorescent labeling and the spin labeling. Because of the dynamic quenching in these donor-acceptor pairs, the lifetime of the

Fluorescence probes to detect lipid-derived radicals

“…The fluorescence properties of NBD-Pen were matched to those of NBD-Me (Supplementary Table 1 and previous reports 22 ). The peak excitation and emission wavelengths exhibited solvatochromic red shifts with increased solvent polarity, as previously reported with NBD-aminohexanoic acid 23 .…”

A New Application of Spin and Fluorescence Double-Sensor Molecules

“…The solvent was a 1:9 mixture of ACN and distilled water solution [ 18 ] and was used in every experiment as a solvent. The synthesis of 3-hydroxymethyl-1-oxyl-4-(pyren-1-yl)-2,2,5,5-tetramethyl-2,5-dihydro-1 H -pyrrole radical and tetrakis(3,5-dicarboxylatophenoxy)-cavitand was carried out in our institute according to published methods [ 12 , 13 ], and their 1 H NMR scan was taken. The applied solvent (acetonitrile) and human serum albumin was purchased from Merck (Darmstadt, Germany).…”

“…Fluorophores as light-sensitive molecules have been in the limelight of clinical research as well since many are used as antibacterial [ 9 ], antifungal [ 10 ], and chemotherapeutic agents [ 11 ]. Since pyrene is widely considered a useful compound for determining solvent environments, 3-hydroxymethyl-1-oxyl-4-(pyren-1-yl)-2,2,5,5-tetramethyl-2,5-dihydro-1 H -pyrrole radical [ 12 ] ( Figure 1 , 1 ) was used in this study as a model molecule for a pharmaceutical agent in a system containing human serum albumin (HSA). This study focuses on the nitroxide 1 interaction with HSA and with the tetrakis(3,5-dicarboxylatophenoxy)-cavitand [ 13 ] ( Figure 1 , 2 ).…”

4‐Amino‐TEMPO as N‐Nucleophile in Palladium‐Catalyzed Aminocarbonylation

“…A synthetic approach to dibenzamido‐TEMPO derivatives as stable monoradicals and biradicals starting from chlorodinitrobenzoic acid chlorides was developed using 4‐amino‐TEMPO . 4‐Amino‐7‐nitrobenzofurazan derivative containing a TEMPO moiety was obtained by reacting 4‐chloro‐7‐nitrobenzofurazan with 4‐amino‐TEMPO . A homologous series of di‐TEMPO biradicals formed from two 4‐amino‐TEMPOs linked by oligomethylene chain was investigated using the electron spin resonance (ESR) spectroscopy .…”