Excimer–monomer fluorescence changes by supramolecular disassembly for protein sensing and quantification

2021 ◽  
Vol 57 (76) ◽  
pp. 9776-9779
Author(s):  
Hongxu Liu ◽  
Jenna Westley ◽  
S. Thayumanavan
Keyword(s):  
Excimer Fluorescence ◽  
Protein Sensing ◽  
Monomer Fluorescence ◽  
Excellent Selectivity

A binding-induced supramolecular dissociation strategy is developed with the ratio of monomer and excimer fluorescence as the tool for protein sensing and quantification, exhibiting excellent selectivity.

‘Excimer’ fluorescence - X. Spectral studies of 9-methyl and 9, 10-dimethyl anthracene

1966 ◽  
Vol 291 (1427) ◽  
pp. 570-582 ◽  
Keyword(s):  
Transition Probabilities ◽  
Entropy Change ◽  
Radiative Transition ◽  
Fluorescence Yield ◽  
Concentration Quenching ◽  
Spectral Studies ◽  
Quantum Yields ◽  
Excimer Fluorescence ◽  
Excimer Formation ◽  
Monomer Fluorescence

The monomer and excimer fluorescence spectra and quantum yields of solutions of 9-methyl anthracene and 9-10-dimethyl anthracene in several solvents were observed as a function of concentration and temperature ( T ). The monomer and excimer fluorescence quantum efficiencies, the molar excimer/monomer fluorescence yield K , and the Stern–Volmer concentration quenching parameter K' , were determined at room temperature. K was observed as a function of T , and the excimer binding energy B evaluated. At high T, K for a given solute is independent of the solvent, indicating that B , ∆ S , the entropy change on excimer formation, and ( k fD ) 0 /( k fM ) 0 , the ratio of the excimer and monomer radiative transition probabilities in vacuo , are solvent-independent molecular properties. It is proposed that the excimer structure of any compound is similar to that of two adjacent molecules in the crystal lattice, with a reduced intermolecular spacing, and that the excimer fluorescence polarization is that of the 1 L a — 1 A monomer fluorescence. This model accounts for the different types of photodimerization behaviour in the meso -substituted anthracenes. It is proposed that all concentration quenching in aromatic hydrocarbons is due to the formation of excimers and/or stable photodimers.

Intramolecular excimer fluorescence from folded ground state rotamers of N,N'dimethyl-N,N'-dipyrenylurea protophanes

2003 ◽  
Vol 81 (6) ◽  
pp. 770-776 ◽  
Author(s):  
Frederick D Lewis ◽  
Todd L Kurth
Keyword(s):  
Ground State ◽  
Fluorescence Spectra ◽  
Fluid Solution ◽  
Absorption And Fluorescence Spectra ◽  
Model Compounds ◽  
Excimer Fluorescence ◽  
Decay Times ◽  
Intramolecular Excimer ◽  
Rotational Equilibrium ◽  
Monomer Fluorescence

The molecular structure, absorption, and fluorescence spectra of N,N'-dimethyl-N,N'-di-1-pyrenylurea and N,N'-dimethyl-N,N'-di-2-pyrenylurea have been investigated and compared to the properties of N,N,N'-trimethyl-N'-pyrenylurea model compounds. Di-1-pyrenylurea exists as a mixture of folded (E,E) syn- and anti-rotamers that interconvert via flipping of one of the pyrene rings to an unfolded (E,Z) rotamer geometry. The symmetric di-2-pyrenylurea exists as a single folded (E,E) conformation which is in equilibrium with a less-stable, unfolded (E,Z) rotamer. The absorption and fluorescence spectra of the dipyrenylureas at 77 K in a rigid glass are similar to those of monopyrenylurea model compounds. However, in fluid solution, the dipyrenylureas exhibit excimer fluorescence and very weak monomer fluorescence which have identical decay times. This behavior is attributed to fast rotational equilibrium between folded rotamers which exhibit excimer fluorescence and unfolded rotamers which exhibit monomer fluorescence. The behavior of the dipyrenylureas is compared with that of other systems that form intramolecular pyrene excimers and diarylureas.Key words: excited state rotamers, dipyrenylureas, pyrene excimers, ureaphane.

'Excimer’ fluorescence III. Lifetime studies of 1:2-benzanthracene derivatives in solution

1964 ◽  
Vol 277 (1369) ◽  
pp. 270-278 ◽  
Keyword(s):  
Light Source ◽  
Fluorescence Yield ◽  
Response Functions ◽  
Fluorescence Lifetimes ◽  
Concentrated Solutions ◽  
Excimer Fluorescence ◽  
Methyl Derivatives ◽  
Excimer Formation ◽  
Lifetime Studies ◽  
Monomer Fluorescence

Observations were made of the fluorescence lifetimes of 1:2-benzanthracene and fourteen of its methyl derivatives in dilute deoxygenated cyclohexane solutions. 1:2-benzanthracene and its 5-, 6- and 10-methyl derivatives were also studied in more concentrated solutions. The time response functions of the monomer and excimer fluorescence components were measured by two independent methods, namely the phase and modulation fluorometer and the pulsed light source techniques. The quantum efficiency of the monomer fluorescence in dilute solutions, and the relative excimer/monomer fluorescence yield I D I M in concentrated solutions, were also observed. The results are analyzed to determine the rate parameters of monomer and excimer fluorescence and of excimer formation and dissociation. It is found that only about half the collisions between excited and unexcited monomers result in excimer formation. This behaviour differs from that of pyrene and it is indicative of weaker excimer interaction in the 1:2-benzanthracene derivatives. The factors determining I D I M are discussed.

‘Excimer’ fluorescence V. Influence of solvent viscosity and temperature

1964 ◽  
Vol 280 (1381) ◽  
pp. 289-297 ◽  
Keyword(s):  
Transition Probability ◽  
Radiative Transition ◽  
Quantum Yields ◽  
Excimer Fluorescence ◽  
Diffusion Controlled ◽  
Relative Quantum ◽  
Fluorescence Characteristics ◽  
Steric Configuration ◽  
Monomer Fluorescence ◽  
Influence Of Solvent

The fluorescence characteristics of pyrene solutions in seven different solvents were studied at temperatures from – 100 to 90 °C. Observations were made of the relative quantum yields of excimer and monomer fluorescence and of the fluorescence spectra and time characteristics. The data, which were analyzed to determine the rate parameters and their associated activation energies, are consistent with an excimer formation process which is diffusion-controlled and reversible. The pyrene excimer binding energy B = 0·40 (± 0·01) eV and its radiative transition probability k f D = 1·2 x 10 7 s -1 are independent of the solvent and of the temperature. This indicates that the excimer has a stable steric configuration.

Monomer and Excimer Fluorescence of 2-Phenylindole in p-Xylene at 20 °C Studied by Frequency-Domain Fluorometry

1993 ◽  
Vol 48 (12) ◽  
pp. 1173-1176
Author(s):  
A. Kawski ◽  
I. Gryczyński ◽  
B. P. Maliwal ◽  
G. Piszczek
Keyword(s):  
Frequency Domain ◽  
Decay Time ◽  
Modulation Frequency ◽  
Fluorescence Decay ◽  
Excimer Fluorescence ◽  
Fluorescence Decay Time ◽  
The Mean ◽  
Concentrated Solution ◽  
Monomer Fluorescence ◽  
Frequency Domain Fluorometry

Abstract The effect of 2-phenylindole (2PI) concentration in p-xylene upon the fluorescence decay time was investigated by frequency-domain fluorometry. The fluorescence decay of a dilute (10~ 5 M) 2PI solution in p-xylene at 20 °C is single exponential with the mean decay time t = 1.87 ns and practically independent of the observation wavelength (A obs) in the fluorescence band. The fluores-cence decay in a highly concentrated solution (6 x 10" 3 M) is heterogenic and depends on A obs . For a given modulation frequency (~ 200 Hz), the fluorescence phase shifts at the longwave observation (440-480 nm) distinctly exceed 90°, thus clearly indicating that the observed (excimer) fluorescence results from a process taking place in the excited state. The fluorescence decays were measured at seven values of A obs (360-480 nm), and all the results were analyzed comprehensively (tj and t 2 are equal for all A obs ; the amplitudes are different). The lifetimes of the excimer state is relatively short (~3.5 ns). Radiative (r e) and non-radiative (t,) rate constants for monomer fluorescence of 2PI in p-xylene were determined using appropriate data from photo-and radioluminescence measure-ments.

‘Excimer’ fluorescence VII. Spectral studies of naphthalene and its derivatives

1965 ◽  
Vol 284 (1399) ◽  
pp. 551-565 ◽  
Keyword(s):  
Fluorescence Spectra ◽  
Entropy Change ◽  
Spectral Studies ◽  
Pure Liquid ◽  
Methyl Ethyl ◽  
Excimer Fluorescence ◽  
Mean Values ◽  
Fluorescence Characteristics ◽  
Excimer Formation ◽  
Monomer Fluorescence

The fluorescence spectra of solutions of naphthalene and fourteen of its methyl, ethyl, dimethyl and trimethyl derivatives were observed as a function of molar concentration c at 20 °C and as a function of temperature from 20 to -70 °C. All the compounds show similar excimer fluorescence characteristics with mean values of the excimer binding energy B = 0.28 ± 0.03 eV and of the excimer interaction energy V' m = 0.765 ± 0.03 eV, with the exception of 1,8-dimethyl naphthalene (B = 0.14 eV) in which excimer formation is sterically hindered. The monomer fluorescence quantum efficiencies and ionization potentials were also determined. The fluorescence spectra of liquid 1,6-dimethyl naphthalene and its solutions in three solvents were observed, and the rate parameters and the entropy change ∆ S on excimer formation were determined, B and ∆ S (= -19.1 cal mole -1 deg -1 ) have similar values in the pure liquid and in cis -decalin and dilute ( c ≤ 1 m) cyclohexane solutions, but slight differences occur in n -heptane and concentrated (c > 1 m ) cyclohexane solutions.

π-Facial Selectivity in 1,3-Dipolar Cycloaddition Reactions of α-Methylidene-γ-lactone Substituted by 4-Methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl Group in γ-Position

2002 ◽  
Vol 67 (3) ◽  
pp. 353-364 ◽  
Author(s):  
Petr Melša ◽  
Ctibor Mazal
Keyword(s):  
Double Bond ◽  
Carboxylic Acid ◽  
Nitrile Oxide ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Enantiomerically Pure ◽  
Nitrile Imine ◽  
Facial Selectivity ◽  
Excellent Selectivity

Diastereoselectivity of 1,3-dipolar cycloaddition reactions of benzyl azide, diazomethane, a nitrile oxide and a nitrile imine to α-methylidene-γ-lactone dipolarophile was effectively controlled by a bulky γ-substituent, 4-methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl in γ-position of the dipolarophile. The dipoles added from the less hindered face of the double bond with an excellent selectivity. Enantiomerically pure dipolarophile was prepared from the easily available (S)-5-oxotetrahydrohydrofuran-2-carboxylic acid.

scholarly journals OBP14 (Odorant-Binding Protein) Sensing in Adelphocoris lineolatus Based on Peptide Nucleic Acid and Graphene Oxide

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 422
Author(s):  
Wenhua Tian ◽  
Tao Zhang ◽  
Shaohua Gu ◽  
Yuyuan Guo ◽  
Xiwu Gao ◽  
...  
Keyword(s):  
Peptide Nucleic Acid ◽  
Antennal Lobe ◽  
Behavioral Regulation ◽  
Dual Roles ◽  
Protein Sensing ◽  
Physiological Functions ◽  
Adelphocoris Lineolatus ◽  
Regulation Strategies ◽  
Odorant Binding

OBPs play a crucial role in the recognition of ligands and are involved in the initial steps of semiochemical perception. The diverse expression of OBP genes allows them to participate in different physiological functions in insects. In contrast to classic OBPs with typical olfactory roles in A. lineolatus, the physiological functions of Plus-C OBPs remain largely unknown. In addition, detection of the expression of insect OBP genes by conventional methods is difficult in vitro. Here, we focused on AlinOBP14, a Plus-C OBP from A. lineolatus, and we developed a PNA-GO-based mRNA biosensor to detect the expression of AlinOBP14. The results demonstrated that AlinOBP14 plays dual roles in A. lineolatus. The AlinOBP14 is expressed beneath the epidermis of the vertex and gena in heads of A. lineolatus, and it functions as a carrier for three terpenoids, while AlinOBP14 is also expressed in the peripheral antennal lobe and functions as a carrier for endogenous compounds such as precursors for juvenile hormone (JH) and JHⅢ. Our investigation provides a new method to detect the expression of OBP genes in insects, and the technique will facilitate the use of these genes as potential targets for novel insect behavioral regulation strategies against the pest.

scholarly journals Immobilization of an Iridium(I)-NHC-Phosphine Catalyst for Hydrogenation Reactions under Batch and Flow Conditions

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 656
Author(s):  
Henrietta Kovács ◽  
Krisztina Orosz ◽  
Gábor Papp ◽  
Ferenc Joó ◽  
Henrietta Horváth
Keyword(s):  
Catalytic Activity ◽  
Ion Exchange ◽  
Heterogeneous Catalyst ◽  
Aqueous Phase ◽  
Levulinic Acid ◽  
Flow Reactor ◽  
High Catalytic Activity ◽  
Flow Conditions ◽  
Hydrogenation Reactions ◽  
Excellent Selectivity

Na2[Ir(cod)(emim)(mtppts)] (1) with high catalytic activity in various organic- and aqueous-phase hydrogenation reactions was immobilized on several types of commercially available ion-exchange supports. The resulting heterogeneous catalyst was investigated in batch reactions and in an H-Cube flow reactor in the hydrogenation of phenylacetylene, diphenylacetylene, 1-hexyne, and benzylideneacetone. Under proper conditions, the catalyst was highly selective in the hydrogenation of alkynes to alkenes, and demonstrated excellent selectivity in C=C over C=O hydrogenation; furthermore, it displayed remarkable stability. Activity of 1 in hydrogenation of levulinic acid to γ-valerolactone was also assessed.

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