Fluorescence Emission Behavior Research Articles

Strongly Coupled Excitonic States in H-Aggregated Single Crystalline Nanoparticles of 2,5-Bis(4-methoxybenzylidene) Cyclopentanone

This paper reports that extremely strongly coupled excitonic states were formed in H-aggregated monocrystalline nanosheets and semicrystalline nanowires of coplanar organic molecules of 2,5-bis(4-methoxybenzylidene) cyclopentanone, due to the highly regular face-to-face stacking of molecular excitons. It was demonstrated that the spectral absorption and fluorescence emission behaviors are dependent on the routes of molecular aggregation and the ordered degree of molecular arrangement in aggregated nanoparticles. In particular, the H-type aggregation of molecules through a highly ordered molecular arrangement in the monocrystalline nanosheets led to the formation of a new exciton coupling state with an energy band higher than that in normal semi-/noncrystalline H-aggregation. A strong symmetric absorption at higher energy bands was thus observed in the solution of nanosheets. Furthermore, the strongly coupled excitonic state may hold all the oscillator strength, leading to the extinction of the original intramolecular electronic transitions of individual molecules and the appearance of new strong absorption and fluorescence emissions at high-energy bands. These results show a perspective that the ability to control the molecular structure and its arrangement in aggregates holds promise for creating novel optical properties in molecular materials.

Cocrystallization and Encapsulation of a Fluorophore with Hexameric Pyrogallol[4]arene Nanocapsules: Structural and Fluorescence Studies

Throwing light on encapsulation: The fluorescent probe molecule 4-[3-(9-anthryl)propyl]-N,N-dimethylaniline (C gray, N blue) crystallizes either exo or endo to the cavity of pyrogallol[4]arene hexamers (O red) and displays markedly different fluorescence emission behavior as a result. In the exo array, the guest alters the packing of the hexamer by forming channels through the extended structure in the solid state (see picture).

Combination of fluorescent switch and electrochemical switch based on a photochromic diarylethene

A new photochromic diarylethene with oligothiophene side arm substituents has been synthesized. This diarylethene undergoes excellent photoisomerization with UV/Vis light irradiation, and shows fluorescence emission and electrochemical behavior. Both the fluorescence emission and oxidation/reduction potential are reversible based on the ring-opening and ring-closing photoisomerization of diarylethene with UV/Vis light irradiation, which may be used as a fluorescent and electrochemical switch. In addition, a combination of photochromism and electrochromism is observed for the diarylethene: the ring-closing reaction can be triggered by electrochemical oxidation while the ring-opening reaction must be photochemically driven.

Structure−Property Relationships in Conjugated Donor−Acceptor Molecules Based on Cyanoanthracene: Computational and Experimental Studies

[reaction: see text] Two series of pi-conjugated bipolar compounds, namely, 9-phenyl-10-anthronitriles (PAN series) and 9-phenylethynyl-10-anthronitriles (PEAN series), having inherent redox centers have been synthesized and their electronic absorption, fluorescence emission, and electrochemical behavior have been studied. Electrochemiluminescence of these molecules bearing weak, strong, and spin-polarized donors is also studied. The observed electronic properties are explained with the help of results obtained from density functional theory (DFT- B3LYP/6-31G) calculations. The structure-property relationships of all the molecules are discussed.

New Advances in Fluorogenic Anion Chemosensors

The development of anion chemosensors is an area of recent interest. We make here a comprehensive review of new advances on anion chemosensing, reported in the literature during the year 2004. The review follows a classification of the sensing systems based on design principles. It comprises: the binding site-signalling subunit approach, the displacement approach and the use of fluoro-chemodosimeters. The first two approximations are based on the use of a suitable anion coordination site coupled with a signalling unit which signals the anion coordination process via changes in its fluorescence behaviour. The two basic subunits are covalently linked in the binding site-signalling subunit approach and not in the displacement approach. In both approaches the fluorescence variation is reversible. The third way to the development of fluorogenic chemosensors is the use of chemodosimeters (also called reagents or reactands) that work usually through irreversible chemical reactions coupled with drastic changes in the fluorescence emission behaviour.

ChemInform Abstract: Synthesis and Fluorescence Emission Behavior of anti‐[2.3](3,10)Phenanthrenophane: Overlap Between Phenanthrene Rings Required for Excimer Formation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Fluorescence Emission Behavior of anti-[2.3](3,10)Phenanthrenophane: Overlap between Phenanthrene Rings Required for Excimer Formation

Abstract Novel anti-[2.3](3,10)phenanthrenophane 3, prepared by the intramolecular [2 + 2] photocycloaddition of 1,3-bis(3-vinyl-10-phenanthryl)propane, exhibited monomer fluorescence. This is in a remarkable contrast with the excimer fluorescence emission from anti-[2.3](3,9)phenanthrenophane 2 with slightly larger overlap between phenanthrene rings than in anti-3.

Influence of Reverse Micellar Environments on the Fluorescence Emission Properties of Tryptophan Octyl Ester

A number of recent studies have presented perspectives on the hydrophobic fluorescence probe tryptophan octyl ester (TOE). This molecule has attracted notable attention as a suitable model for the natural fluorophore tryptophan, in case of membrane proteins. We report here, for the first time, the fluorescence emission behaviour of TOE in reverse micelles of aerosol-OT (AOT) in n-heptane, containing different amounts of water. Relevant studies in representative homogeneous solvent media are also included for comparison. The fluorescence emission parameters (especially emission maximum, relative intensity, and anisotropy) of TOE are found to exhibit significant variation upon changes in the water/surfactant molar ratio (w0) of the reverse micelles. Fluorescence decay studies on TOE which we have also performed, indicate biexponential decay kinetics in reverse micelles as well as in homogeneous solvent media. The implications of these findings are examined in relation to the potentialities of TOE as a novel fluorescence probe for membrane proteins present in water restricted environments prevailing at the interfaces of biomembranes (for which reverse micelles serve as ideal model systems).

Synthesis and fluorescence emission behavior of novel anti-[2. n](3,9)phenanthrenophanes

Novel syn- and anti-[2. n](3,9)phenanthrenophanes ( n=3,4) were successfully prepared by the intramolecular [2+2] photocycloaddition of α,ω-bis(3-vinyl-9-phenanthryl)alkanes. The anti-isomer of n=3 was found to give excimer fluorescence in spite of the only partially overlapping phenanthrene rings, although that of n=4 gave monomer fluorescence.

Polycyclic aromatic hydrocarbon solute probes Part XII: Dissimilar fluorescence excitation/emission behavior between alkylpyrene and alkylcoronene derivatives and the parent pah molecule

Fluorescence excitation and emission behavior are reported for methylcoronene, 1,2-dimethylcoronene, 2-isopropyl-pyrene, 4-isopropylpyrene, 2,4,7,10-tetraisopropylpyrene, 1,3,6,8-tetraisopropylpyrene, 1,3,5,7,9-pentaisopropylpyrene, 2,7-di- tert-butylpyrene, 2,7-di-(dimethylpropyl)pyrene, 1,3,6,8-tetracyclopentylpyrene and 1,3,6,8-tetracyclohexylpyrene dissolved in various organic solvents of varying solvent polarity. Experimental results are used to test a potential screening method for determining whether a given alkyl-substituted polycyclic aromatic hydrocarbon (PAH) solute is likely to exhibit probe character, as evidenced by a systematic variation in the ratios of the fluorescence intensities of select emission bands with solvent polarity. Of the eleven solutes studied, only 4-isopropylpyrene, methylcoronene and 1,2-dimethylcoronene showed useful solvent polarity probe character. 1,3,6,8-Tetraisopropylpyrene, 1,3,5,7,9-pentaisopropylpyrene, 1,3,6,8-tetracyclohexylpyrene and 1,3,6,8-tetracyclopentylpyrene exhibited slight probe behavior; however, the dynamic ranges covered in emission intensity ratios were believed to be too small for many practical applications when compared against the experimental uncertainty associated with the measured values.

Characterization of the Fluorescence Emission Properties of 7-Azatryptophan in Reverse Micellar Environments

The amino acid analogue 7-azatryptophan has attracted significant recent attention as a novel optical probe for protein structure, function and dynamics. We report here, for the first time, its fluorescence emission behavior in a membrane mimetic model system, namely reverse micelles of aerosol-OT in n-heptane, containing varying amounts of added H2O or D2O. Upon increase in the water/surfactant molar ratio from 0.5 to 50 the emission maximum undergoes a pronounced red shift (by 20 nm), which is accompanied by dramatic quenching of the fluorescence emission and sharp decrease in its average lifetime. These data are used to infer the microenvironments of the fluorophore in the reverse micelles. Furthermore, the highly sensitive dependence of the fluorescence emission parameters of 7-azatrytophan on the water content of the reverse micelles highlights its suitability as a probe for water restricted environments, with possible applications to interfacial regions of biomembranes.

Adaptation of fluorescence excitation-emission micro-spectroscopy for characterization of single hydrocarbon fluid inclusions

Until now, fluorescence characteristics of hydrocarbon fluid inclusions have been limited in measurement by the requirement to use bandpass filters, dichroic mirrors and neutral density beamsplitters/quartz wedges in the optical light path. Measurements have generally been restricted to monitoring emission spectra from ca. 400 nm and above because the microscope arrangements have used fluorescence “cubes” optimized for specific excitation wavelengths such as the emission lines in the mercury spectrum. This has meant that only those lines can be used to excite an inclusion and recording of excitation spectra is not possible. Well established luminescence techniques of excitation-emission and synchronous excitation-emission spectroscopy have been expanded into the micro-scale domain by the use of a commercially available luminescence spectrometer adapted to a microscope via UV-transparent Suprasil R fiber optic cables. These techniques were developed to pursue non-destructive fingerprinting of individual hydrocarbon fluid inclusions by use of the quantitative parameters of optimum excitation wavelength and Stokes' shift. The technique of fluorescence excitation and emission micro-spectrometry (FLEEMS) has been tested on different hydrocarbon fluid inclusion samples from reservoir rocks of the Norwegian continental shelf and from a Norwegian on-shore hydrocarbon bearing diabase dyke. This new technology readily allows unique luminescence information to be extracted for discrimination of hydrocarbon fluid inclusions with visually identical fluorescence color and emission behavior in the visible region. Spectroscopic information in the range of 240–800 nm is accessible with a wavelength accuracy better than 0.25 nm and reproducibility better than 0.05 nm for both excitation and emission. Signal/noise ratios are higher than previously available for microscopic applications. This technology can readily be adapted to most brands of microscopes in a modular way without any irreversible microscope customization.

Spectrochemical Investigations of Preferential Solvation. Part 3. Extension of the Khossravi-Connors-Skwierczynski Two-Step Competitive Solvation Model to Fluorescence Emission Behavior of Polycyclic Aromatic Hydrocarbon Solvent Polarity Probes Dissolved in Binary Solvent Mixtures

Abstract The Khossravi-Connors-Skwierczynski step-wise competitive exchange model, which has previously led to successful descriptive expressions for solvent effects on solubility, surface tension and molecular complex formation, is modified to model fluorescence emission behavior of polycyclic aromatic hydrocarbon solutes dissolved in binary solvent mixtures. Expressions are derived for calculating numerical values of the various step-wise exchange equilibrium constants from measured emission intensity ratios in mixed solvents and from measured absolute emission intensities in both pure solvents. Computation procedure is illustrated using measured fluorescence properties of pyrene, benzo [e] pyrene, benzo [ghi] perylene, coronene, methylcoronene and 1,2-dimethylcoronene in n-heptane+ 1,4-dioxane and n-heptane + tetrahydrofuran mixtures. Also discussed are similarities and differences between the newly-derived expressions and ones based upon a recently published spectrofluorometric probe method, and the s...

Spectroscopic Properties of Polycyclic Aromatic Compounds. Part IV: Effect of Solvent Polarity and Nitromethane on the Fluorescence Emission Behavior of Select Bipolycyclic Aromatic Hydrocarbons

Fluorescence emission behavior is reported for 1,1′-binaphthalene, 2,2′-binaphthalene, 9,9′-bianthracene, 9,9′-biphenanthrene, 1,1′-methylene-bisnaphthalene, and 1,1′,2,2′-tetrahydro-5,5′-biacenaphthylene dissolved in organic nonelectrolyte solvents of varying polarity, refractive index, and dielectric constant. Fluorescence measurements are used to classify the six bipolycyclic aromatic hydrocarbon (bi-PAH) solutes as either solvatochromic probe or nonprobe molecules, depending upon whether measured fluorescence properties vary with solvent nature. Of the bi-PAHs studied, only 9,9′-bianthracene exhibited probe character. Possible correlations between 9,9′-bianthracene's maximum intensity emission wavelength and select functions of solvent refractive index and dielectric constant were examined. Also reported is the effect that nitromethane has on bi-PAH fluorescence emission intensities.

Spectroscopic Investigation of Fluorescence Quenching Agents. Part IV: Selectivity of Nitromethane for Discriminating between Alternant versus Nonalternant Polycyclic Aromatic Hydrocarbons in Solvents of Differing Polarities

To further assess the applicability of nitromethane as a selective quenching agent for alternant vs. nonalternant polycyclic aromatic hydrocarbons in HPLC analysis, we measured the effect that it has on the fluorescence emission behavior of 96 different polycyclic aromatic hydrocarbons dissolved in a binary ethyl acetate/acetonitrile solvent mixture. Nitromethane quenching results are compared with previously reported acetonitrile, aqueous/acetonitrile, and toluene/acetonitrile solvent mixtures. Results of these measurements revealed that the “selective quenching” rule is obeyed for the vast majority of PAHs in all solvents considered thus far, with the coronene derivatives being the only major exceptions.

Spectrochemical investigations of preferential solvation: fluorescence emission behavior of select polycyclic aromatic hydrocarbon solute probes dissolved in mixed solvents

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectrochemical investigations of preferential solvation: fluorescence emission behavior of select polycyclic aromatic hydrocarbon solute probes dissolved in mixed solventsWilliam E. Acree Jr., Sheryl A. Tucker, and Denise C. WilkinsCite this: J. Phys. Chem. 1993, 97, 43, 11199–11203Publication Date (Print):October 1, 1993Publication History Published online1 May 2002Published inissue 1 October 1993https://doi.org/10.1021/j100145a014RIGHTS & PERMISSIONSArticle Views159Altmetric-Citations47LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (617 KB) Get e-Alerts

Spectrofluorometric Probe Method for Examining Preferential Solvation in Binary Solvent Mixtures

A spectrofluorometric method is developed to examine preferential solvation of a probe molecule dissolved in binary solvent mixtures. The method assumes that the solvational sphere around every fluorophore is solvated by only one type of solvent component and that each solvated fluorophore contributes to the measured emission intensity. Expressions derived from the model are illustrated with the use of observed fluorescence emission behavior of 3,4-dihydrobenzo[ghilperylene dissolved in binary n-heptane + 1,4-dioxane and dibutyl ether + acetonitrile solvent mixtures, which were measured as part of the present study.

Spectroscopic Investigation of Fluorescence Quenching Agents. Part III: Effect of Solvent Polarity on the Selectivity of Nitromethane for Discriminating between Alternant versus Nonalternant Polycyclic Aromatic Hydrocarbons

To better assess the applicability of nitromethane as a selective quenching agent for alternant versus nonalternant polycyclic aromatic hydrocarbons in HPLC, TLC, and HPTLC analysis, we measured the effect that it has on the fluorescence emission behavior of 96 different polycyclic aromatic hydrocarbons dissolved in binary toluene/acetonitrile solvent mixtures. Results of these measurements revealed that the “selective quenching” rule is obeyed for the vast majority of PAHs, with the coronene derivatives being the only major exceptions. Fluorescence emission spectra are also reported for benzo[g]chrysene, naphtho[2,3g]chrysene, 4 H-benzo[c]cyclopenta[mno]chrysene, dibenzo[ghi,mno]fluoranthene (commonly called corannulene), rubicene, diacenaphtho[l,2j:l‘,2'l]fluoranthene, 10-methyl-benzo[b]fluoranthene, 3-methoxybenzo[k]fluoranthene, and 3-hydroxybenzo[k]fluoranthene in organic nonelectrolyte solvents of varying polarity. Calculated emission intensity ratios failed to vary systematically with solvent polarity, and all nine of the aforementioned solutes were thus classified as nonprobe molecules.

Spectroscopic Investigation of Fluorescence Quenching Agents: Effect of Nitromethane on the Fluorescence Emission Behavior of Select Cyclopenta-PAH, Aceanthrylene, and Fluorene Derivatives

Nitromethane is examined as a selective fluorescence quenching agent for “alternant” alkyl-substituted polycyclic aromatic hydrocarbons (PAHs). Fluorescence emission behavior is reported for 11 H-benz[bc]aceanthrylene, 4 H-cyclopenta[def]phenanthrene, 4 H-cyclopenta[def]chrysene, 13 H-dibenzo[a,g]fluorene, 13 H-dibenzo[a,i]fluorene, 4 H-benzo[b]cyclopenta[mno]chrysene, 4 H-cyclopenta[pqr]picene, 7 H-dibenzo[c,g]fluorene, 9 H-benz(6,7)indeno[1,21]phenanthrene, 4 H-benzo[b]cyclopenta[jkl]triphenylene, 13 H-dibenz[bc,k]aceanthrylene, 13 H-dibenz[bc,l]aceanthrylene, and 4 H-benzo[def]cyclopenta[mno]chrysene dissolved in organic solvents of varying polarity and in acetonitrile or aqueous-acetonitrile solvent mixtures at various nitromethane concentrations. Results of these measurements show that nitromethane quenches fluorescence emission of the thirteen solutes studied, which is in complete agreement with what would be expected on the basis of the fact that all solutes are “alternant” polycyclic aromatic hydrocarbons.

Spectroscopic Properties of Polycyclic Aromatic Compounds: Examination of Nitromethane as a Selective Fluorescence Quenching Agent for Alternant Polycyclic Aromatic Nitrogen Hetero-Atom Derivatives

Nitromethane is examined as a selective fluorescence quenching agent for alternant polycyclic aromatic nitrogen hetero-atoms (PANHs). Fluorescence emission behavior is reported for 1-azapyrene, 2-azapyrene, 4-azapyrene, 4-azachrysene, 12-azabenzo[a]pyrene, phenanthro[9, 10g]isoquinoline, phenanthro[2,3h]isoquinoline, phenanthro[3,2h]-isoquinoline, 2-azabenz[a]anthracene, 1-azabenz[a]anthracene, 9-azabenz[a]anthracene, dibenzo[c,i]phenanthro[1,10,9,8anmlk]phenanthridine, diphenanthro[9,10,1def;1',10',9'hij]phthalazine, and benz[de]isoquino[1,8gh]quinoline dissolved in acetonitrile or aqueous-acetonitrile solvent mixtures at various nitromethane concentrations. Results of these measurements show that nitromethane does quench fluorescence emission of ten of the solutes studied; however, phenanthro-[2,3h]isoquinoline, 9-azabenz[a]anthracene, benz[de]isoquino[1,8gh]-quinoline, and dibenzo[c,i]phenanthro[1,10,9,8anmlk]phenanthridine are notable exceptions.