1086-00-6Relevant academic research and scientific papers
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.
A Probe for the selective and parts-per-billion-level detection of copper(II) and mercury(II) using a micellar medium and its utility in cell imaging
Kumari, Namita,Jha, Satadru,Misra, Santosh K.,Bhattacharya, Santanu
, p. 1059 - 1064 (2014)
A novel colorimetric probe 1 based on the picolyl moiety has been designed and synthesized. Probe 1 is composed of a pyrene and a bispicolyl amine (BPA) unit, in which the BPA moiety acts as a binding unit and the binding phenomenon is sensed from the changes in the signaling subunit. The probe detects Cu 2+ specifically in water and both Cu2+ and Hg2+ efficiently in neutral Brij-58 micellar media. The probe shows a color change visible to the naked eye upon addition of metal ions. Notably, in a micellar medium, probe 1 can detect both the Cu2+ and Hg2+ ions even at parts-per-billion levels. Furthermore, the probe shows ratiometric detection of both the metal ions making the sensing quantitative. The two metal ions could be discriminated both visibly under a UV lamp and with the use of fluorescence spectroscopy. The probe could be also used in biological cell lines for the detection of both Hg2+ and Cu2+ ions.
A sugar-aza-crown ether-based fluorescent sensor for Cu2+ and Hg2+ ions
Hsieh, Yu-Chi,Chir, Jiun-Ly,Yang, Shih-Tse,Chen, Shau-Jiun,Hu, Ching-Han,Wu, An-Tai
, p. 978 - 981 (2011)
A sugar-aza-crown ether (SAC)-based fluorescent sensor 4 was prepared. It contains a pyrene as the fluorophore and its fluoroionophoric properties toward transition metal ions were investigated. Chemosensor 4 exhibits highly selective recognition toward Cu2+ and Hg2+ ions among a series of tested metal ions in methanol solution. The association constants for 4Cu 2+ and 4Hg2+ in methanol solution were calculated to be 7.4 × 101 M-1 and 4.4 × 103 M -1, respectively. Chemosensor 4 formed complexes with the Cu 2+ or Hg2+ ion at a 1:1 ligand-to-metal ratio with a detection limit of 1.3 × 10-4 M Cu2+ and 1.26 × 10-5 M Hg2+, respectively.
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.
Synthesis of porphyrin-dendrimers with a pyrene in the periphery and their cubic nonlinear optical properties
Morales-Espinoza, Eric G.,Lijanova, Irina V.,Morales-Saavedra, Omar G.,Torres-Zuniga, Vicente,Hernandez-Ortega, Simon,Martinez-Garcia, Marcos
, p. 6950 - 6968 (2011)
Dendrons of pyrene derivatives were attached to a porphyrin core. A marked effect in solution for the dendrimers was observed in the absorption spectra. All the compounds obtained were characterized by 1H-, 13C-NMR, FTIR, UV-vis, MALDI-TOF or FAB+ mass spectrometry and elemental analysis. The cubic nonlinear optical behavior of some the synthesized compounds was tested via Z-Scan measurements in spin-coated film samples.
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.
Bispyrene/surfactant assemblies as fluorescent sensor platform: Detection and identification of Cu2+ and Co2+ in aqueous solution
Ding, Liping,Wang, Shihuai,Liu, Yuan,Cao, Jianhua,Fang, Yu
, p. 8866 - 8875 (2013)
A cationic bis-pyrene derivative was prepared and its assemblies with anionic surfactant to function as fluorescent sensor platforms for heavy metal ions in aqueous solution were evaluated. Optical spectroscopy measurements illustrated that both UV-vis absorption and fluorescence emission spectra of bis-pyrene could be well enhanced in the assemblies with the anionic surfactant, SDS. Moreover, fluorescence quenching studies revealed that the sensitivity of bis-pyrene/SDS assemblies is highly dependent on the concentration of SDS. The optimized sensor platform exhibited not only a high sensitivity towards both Cu2+ and Co2+ in aqueous solution with detection limits lower than 100 nM but also a high selectivity towards these two metal ions over a series of divalent metal ions including Ba2+, Ca2+, Hg2+, Mg2+, Ni2+, Pb2+, Zn 2+, Cd2+, and Fe3+. The high sensitivity was demonstrated to be due to the electrostatic interaction between the metal cations and the anionic surfactants, which dramatically increases the local concentration of metal ions in the near vicinity of pyrene moieties. Moreover, the metal ion target could be identified by addition of glycine to the quenched system, where a dramatic turn-on fluorescence was observed for the Cu 2+-quenched system whereas a further turn-off fluorescence was found for the Co2+-quenched system. Furthermore, the recovery of Cu 2+-quenched fluorescence could be utilized to provide a turn-on fluorescence sensor for neutral amino acids. 2013 The Royal Society of Chemistry.
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.
Sugar thiacrown-ether appended calix[4]arene as a selective chemosensor for Fe2+ and Fe3+ ions
Ling, Irene,Hashim, Rauzah,Sabah, Karem J.
, p. 88038 - 88044 (2015/11/09)
A new fluorescent chemosensor derived from sugar-thiacrown-ether appended calix[4]arene, coupled with pyrene units was designed and synthesized. Upon the addition of Fe2+, or Fe3+, changes were observed in both the fluorescence and absorption spectra. The fluorescence intensities are significantly quenched indicating high selectivity for these two metal ions over other transition metals investigated.
