1086-00-6Relevant articles and documents
Two pyrenylalanines in dihydrofolate reductase form an excimer enabling the study of protein dynamics
Chen, Shengxi,Wang, Lin,Fahmi, Nour Eddine,Benkovic, Stephen J.,Hecht, Sidney M.
, p. 18883 - 18885 (2012)
Because of the lack of sensitivity to small changes in distance by available FRET pairs (a constraint imposed by the dimensions of the enzyme), a DHFR containing two pyrene moieties was prepared to enable the observation of excimer formation. Pyren-1-ylalanine was introduced into DHFR positions 16 and 49 using an in vitro expression system in the presence of pyren-1-ylalanyl- tRNACUA. Excimer formation (λex 342 nm; λem 481 nm) was observed in the modified DHFR, which retained its catalytic competence and was studied under multiple and single turnover conditions. The excimer appeared to follow a protein conformational change after the H transfer involving the relative position and orientation of the pyrene moieties and is likely associated with product dissociation.
Radiation-induced C-C Bond Cleavage in 1,2-Diarylethanes as Model Compounds of Coal. Part 2. Pulse and Steady-state Radiolysis of 1,2-Di(pyren-1-yl)ethane in Tetrahydrofuran, Dimethoxyethane and Toluene in the Presence of Sodium Dihydridobis(2-methoxyethoxy)aluminate
Solar, Sonja,Getoff, Nikola,Haenel, Matthias W.,Richter, Udo-Burckhard
, p. 891 - 904 (1993)
1,2-Di(pyren-1-yl)ethane (1,2-DPE) has been used as a model for coal to study the C-C bond cleavage of the ethano linkage in the radiolysis of solutions containing NaAlH2(OCH2CH2OCH3)2 .Transient species were investigated by pulse radiolysis of solutions of 1,2-DPE, 1-methylpyrene (1-MP) and pyrene (P) in THF, DME and toluene in the absence and the presence of NaAlH2(OR)2.In the presence of the latter stabilized and long-lived radical anion/sodium cation pairs of 1,2-DPE, 1-MP and P were generated even in the non-polar solvent toluene.The reaction mechanisms differ substantially for the ether solvents (THF or DME) and solutions in toluene.In the case of the ether solvents (SH) NaAlH2(OR)2 acts as a scavenger for solvent radical cations SH.+ and solvent cations SH(H(+)) generated through ionization.This produces stabilized sodium cation/electron pairs (Na(+), es(-)) which reduce the aromatic substrates to their radical anion/sodium cation pairs.The prevailing species generated in the radiolysis of solutions in toluene are electronically excited molecules of the solvent and the substrate from which the excited triplet molecules are preferentially reduced to radical anions by NaAlH2(OR)2 in an electron-transfer process.Steady-state radiolysis ((60)Co γ-rays) of solutions of 1,2-DPE in THF, DME or toluene containing NaAlH2(OR)2 resulted in the C-C bond cleavage of the ethano linkage.This is attributed to the unstable dianion (1,2-DPE(2-), 2Na(+)) formed in two successive reductions via (1,2-DPE.-, Na(+)).UV-VIS spectroscopy and product analysis showed that the radiation-induced reduction of 1,2-DPE, 1-MP and P requires lower doses in THF and DME than in toluene.However, reactions of (1,2-DPE.-, Na(+)) with THF and DME to form substrate-solvent addition products limit C-C bond cleavge (16percent in THF and 32percent in DME).The inertness of toluene towards such side reactions makes the radiation-induced cleavage process of 1,2-DPE in this solvent (despite of the higher dose required) much more efficient than in THF and DME, yielding after hydrolysis up to 52percent 1-MP.Radiation-induced reduction of polycyclic arenes in the NaAlH2(OR)2-toluene system is very useful for investigating the radical anions of these arenes by UV-VIS and EPR spectroscopy, since essentially no other interfering species are formed.
Mixed bifunctionality. 4. Antitumor activity of alkylating derivatives of polycyclic aromatic hydrocarbons as a function of structure and of vehicle.
Peck,O'Connell
, p. 68 - 70 (1972)
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A spiropyran with enhanced fluorescence: A bright, photostable and red-emitting calcium sensor
Sylvia, Georgina M.,Heng, Sabrina,Bachhuka, Akash,Ebendorff-Heidepriem, Heike,Abell, Andrew D.
, p. 1240 - 1244 (2018)
A rationally designed, pyrene-spiropyran hybrid Ca2+ sensor (Py-1) with enhanced fluorescence intensity compared to a standalone spiropyran analogue is presented. Importantly, Py-1 retains the characteristic red emission profile of the spiropyran, while fibre-based photostability studies show the sensor is stable after multiple cycles of photoswitching, without any sign of photodegradation. Such properties are of real advantage for cell-based sensing applications. An interesting observation is that, Py-1 presents with two excitation options; direct green excitation (532 nm) of the photoswitch for a red emission, and UV excitation (344 nm) of the component pyrene, which gives rise to distinct blue and red emissions. This proof-of-concept hybrid sensing system presents as a more general approach to brighter spiropyran-based sensors.
Fluorescence emission control and switching of oxymethylcrowned spirobenzopyrans by metal ion
Ahmed, Saleh A.,Tanaka, Mutsuo,Ando, Hisanori,Tawa, Keiko,Kimura, Keiichi
, p. 6029 - 6036 (2004)
Oxymethylcrowned spirobenzopyran 1 and pyrenylspirobenzopyran 2 were synthesized, and fluorescence emission of their corresponding merocyanine form was examined in the presence of metal ions. For 2, fluorescence emission derived from the pyrene moiety was completely quenched by photoinduced electron transfer (PET) of the nitrogen atom when the merocyanine form was not produced, namely, without metal ions. However, when 2 was converted to the merocyanine form by the complexation of its crown ether with a metal ion, fluorescence resonance energy transfer (FRET) from the pyrene to the merocyanine moieties took place to produce fluorescence emission. This result demonstrates that the spirobenzopyran isomerization can function as a fluorescence emission switch. Fluorescence quantum yield measurement for 1 and 2 showed that fluorescence emission depends on the binding metal ion in which the fluorescence quantum yield generally increased with the increase of metal ion radius.
Trace level Al3+ detection in aqueous media utilizing luminescent ensembles comprising pyrene laced dynamic surfactant assembly
Dey, Nilanjan,Bhattacharya, Santanu
, p. 2352 - 2359 (2018/02/20)
Easily synthesizable amphiphilic probes have been designed for the detection of Al3+ exclusively at mesoscopic interfaces. The surface charge of the surfactant assemblies and the fluidity of the lipid aggregates show pronounced effects on the extent of Al3+ detection. Excellent sensitivity has been observed specifically in the presence of anionic surfactants and the lipid membranes with more sol-like characteristics. Moreover, a variation in the modes of Al3+ complexation is observed on shifting from one regioisomer to another. For instance, the para isomer exhibits a 1:2 stoichiometry with the Al3+ ion, while for the ortho-isomer, it is a 1:1 interaction. Considering the excellent sensitivity of the probe molecule towards Al3+, the present system has been utilized for the estimation of soluble aluminum content in acidic soil samples as well as in pharmaceutical tablets. Low-cost paper strips are developed for rapid, on-site detection of Al3+ without involving advanced instruments or trained technicians. Finally, the bioimaging of Al3+ is achieved in cervical cancer (HeLa) cells.
