Pyrene modified

Wanninger-Weifi C, Valis L, Wagenknecht H-A (2008) Pyrene-modified guanosine as fluorescent probe for DNA modulated by charge transfer. Bioorg Med Chem 16 100-106... 

Mayer, E., Valis, L., Huber, R., Amann, N. and Wagenknecht, H. A. (2003). Preparation of pyrene-modified purine and pyrimidine nucleosides via Suzuki-Miyaura cross-couplings and characterization of their fluorescent properties. Synthesis 2335-2340. 

Figure 25.4 The bay region dihydrodiol epoxide route of benzo[a]pyrene. (Modified from Dipple, A. 1985.

Figure 7 Guest-induced dissociation of the association dimer of pyrene-modified y-CDs.

Calixarenes modified with a reporter site are equally competent chemosen-sors for the detection of a variety of analytes according to Scheme 6, especially when the analyte is cationic. The tt-cavity of a tetraanionic resorcin[4]arene readily binds cationic guests, a feature that Inouye et al. have exploited in the development of an acetylcholine chemosensor [358], The fluorescence from a pyrene-modified N-alkylpyridinium is strongly quenched upon its association with the tetraphenolate form of resorcin[4]arene (24). This quenching is consis-... 

Following this same approach, Jin and coworkers have prepared a nearly identical pyrene-modified calixarene, 38, where the methoxy groups are replaced by ester functionalities [377], Na+ and K+ ions perturb the relative intensities of excimer and monomer emission in much the same manner as 37. Unlike 37, however, 38 is not sensitive to Li+ ion. 

This conformation would place the chromophore residue into a stacked situation within the adjacent DNA bases while replacing the counterbase of the complementary strand. To obtain more structural information, NOESY experiments were performed on the pyrene-modified nucleosides. The spectra of the modified pyrimidines Py-dU and Py-C clearly showed a significant NOESY cross peak between H-6 of the dU part or the C part, respectively and H-2 of the corresponding 2 -deoxyribose moiety. The NOESY cross peak was comparably as strong as the cross peaks between H-2 and H-l or H-3, respectively. These NMR results can only be explained with the preferred anti conformation of these nucleosides. 

By use of the nucleoside Py-dU we prepared a range of pyrene-modified duplexes by phosphoramidite chemistry [29]. The covalently attached pyrene group is located outside the DNA base stack. On excitation intramolecular ET in the Py-dU group represents injection of an excess electron into the DNA base stack. The differences between the prepared DNA duplexes are the bases located next to the Py-dU group. 

FIG. 4 Fluorescence emission spectra of a solution of lysozyme and pyrene-modified polyfacrylamido methylpropanesulfonate) in 0.25 M NaCl and at varying pH. pH 12.0 (1), 11.0 (2), 10.0 (3), and 9.0 (4). Excitation wavelength 295 nm. The decrease of the intensity at 340 nm (essentially tryptophane) and the increase at 400 nm (pyrene) indicates the energy transfer from lysozyme to the polyelectrolyte. (Reprinted with permission from Ref. 21. Copyright 1995 John Wiley Sons, Inc.)... 

In connection with the 2 2 complex between y-CD and pyrene, we prepared pyrene-modified y-CD (D). This modified y-CD forms a stable association dimer and exhibits a strong pyrene excimer emission around 470 nm (5). The association dimer was converted into a 1 1 host-guest complex upon est action (eq. 1 in Figure 1), and consequently the excimer emission decreased with increasing guest concentration (Figure 2). The extent of the decrease of the excimer emission intensity to the original... 

The C5 position of dU has been used to attach a variety of labels or reporter groups, in particular fluorophores ° (see section 3.5). The pyrene-modified analogue (39) has been used to detect RNA bulge conformations in the HIV-TAR RNA sequence where the fluorescence is greatly enhanced,and as a donor for the red emitter nile red (40) when the two dyes are adjacent in duplex DNA the result is white light that is emitted upon excitation of (39). A zinc-porphyrin complex has been added to C5 of dU for use in electron transfer. Norbornene has been attached via an alkyne linker for post-synthetic modification with nitrile oxides in a copper-free Click reaction, " and various dienes have been attached for Diels-Alder tagging of DNA. The photoaffinity tag (41) has been incorporated into DNA adjacent to a damaged DNA base (8-oxo-dG or thymine dimer) such that when exposed to repair systems, the repair enzyme is trapped by the diazirine for mass spectroscopic characterisation. ... 

On the other hand, Sasaki and coworkers inserted a pyrene-modified crown ether into liposomes. The lateral distribution of the crown ether in the membrane depends on the presence of metal ions, and the relative intensity of... 

The discovery of the fluorescence variation of pyrene-modified y-CD 1 upon addition of guests prompted the use of fluorophore-modified CD as chemosensors [9,10]. The pyrene-modified y-CD forms an association dimer in aqueous solution and exhibits excimer emission around 470 nm. The addition of a guest into the solution of the pyrene-modified y-CD causes a remarkable decrease in the excimer emission and an increase in the monomer emission around 378 and 397 nm. The guest-induced circular dichroism and absorption variations of 1 substantiated that this fluorescence variation occurs associated with the conversion from the association dimer to a 1 1 host-guest complex (Fig. 1). Since the... 

Fig. 1. Guest-induced conformational change of pyrene-modified y-cyclodextrin.

Kumar et reported the synthesis of pyrene-modified nucleotides and their effects in secondary nucleic acid structures. Pyrene was attached to the 5 -position of thymidine (26a) or to the 2 -position of 2 -deojgairidine via a triazolomethylene linker (26b), or via a triazole linker (26c). These nucleosides were converted into their phosphoramidites and then incorporated into oligonucleotides, and analysed by thermal stability and fluorescence studies. These experiments indicated that these oligonucleotides can act as specific recognition probes. 

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