Nonconjugated Chromophores Research Articles

Identification of residual non-biodegradable organic compounds in wastewater effluent after two-stage biochemical treatment

AbstractThe main non-biodegradable compounds (soluble microbial product – SMP) of wastewater from the Maotai aromatic factories, located in the Chishui river region, were analyzed by UV spectroscopy, and by solid-phase extraction followed by gas chromatography coupled to mass spectrometry, after a two-stage biochemical treatment. The UV-Vis spectra revealed that the wastewater contained two double-bonds in conjugated systems (conjugated diene or α, β- unsaturated ketone, etc.) and simple non-conjugated chromophores containing n electrons from carbonyl groups or the like. The residual organic non-biodegradable substances were identified using SPE-GC/MS analysis as complex polymers containing hydroxyl, carbonyl, and carboxyl functional groups with multiple connections to either benzene rings or heterocyclic rings. As these compounds are difficult to remove by conventional biochemical treatments, our findings provide a scientific basis for the design of efficient new strategies to remove SMP from wastewater.

Cover Picture: Switchable Ambient‐Temperature Singlet–Triplet Dual Emission in Nonconjugated Donor–Acceptor Triarylboron–PtII Complexes (Chem. Eur. J. 25/2009)

AbstractSinglet–triplet dual emission has been achieved in single molecules containing triarylboron and N‐(2′‐pyridyl)‐7‐azaindole chromophores. The structure of a Pt(II) complex and its dual emission spectrum are depicted in the cover picture. In their Full Paper on page 6131 ff., S. Wang et al. demonstrate that metal chelation and nonconjugated chromophores with a common excitation wavelength facilitate singlet and triplet dual emission in solution at ambient temperature that originate from two separate parts of the molecule.magnified image

Synthesis of Star Polymer Architectures with Site-Isolated Chromophore Cores

We report the synthesis of star polymers with site-isolated chromophores obtained by nitroxide-mediated polymerization and reversible addition−fragmentation chain transfer techniques through the “arm first” method. Linear polymer precursors such as α-alkoxyamine-terminated polystyrene (PS) and thioester-terminated poly(acrylic acid) (PAA) were prepared followed by the addition of fluorescent divinyl cross-linkers derived from the fluorene and thiophene families. We first synthesized organic soluble star polymers containing hexyl-functionalized fluorene and thiophene cross-linkers with PS. Second, ethylene oxide (EO)-functionalized fluorene cross-linkers were incorporated into PAA linear precursors to give water-soluble star polymers with site-isolated chromophore core units. The photoluminescence increased significantly while the emitting wavelength corresponded with highly dilute, nonconjugated chromophores in solution. This effect is indicative for a highly localized concentration of chomophores in the star polymer cores that are covalently connected but do not show the typical effects of concentrated monomers in solution such as aggregation, fluorescence quenching, and a red shift of emission wavelength. The site isolation of chomophores in star polymers leads to nanostructures with highly photoluminescent core units while the emanating linear polymers are available for further functionalizations.

Design of a new molecular fluorescent signalling system acting via both electron and energy transfer

A new molecular fluorescent signalling compound has been designed and synthesized in this work. In a molecule, there are two non-conjugated chromophores included, one of them acts as an electronic acceptor and energy transfer donor, while the other is used as an acceptor of energy transfer. The advantages of this design are as follows: first, it can lead to a long-wavelength emission upon excitation at a short wavelength after the system was protonized. The second is that this system offers a large flexibility in choosing dyes with different wavelength of absorption and emission.

Fluorescence quenching in bichromophoric systems with nonconjugated chromophores: 5-substituted derivatives of l,3,5-triaryl-2-pyrazoline

The spectral and fluorescent properties of l,3,5-triphenyl-2-pyrazoline derivatives with acceptor substituents in benzene ring in the 5 position of the pyrazoline cycle were investigated. The corresponding pyrazoline derivative, in which phenyl radical in the 5 position is replaced by a fragment with an extended conjugated system-2.5-diphenyloxazolyl-was studied as well. The noticeable decrease in fluorescence quantum yield in comparison with the nonsubstituted molecule is characteristic of the compounds studied, which belong to the broader class of bichromophoric molecules with nonconjugated chromophores. The existence of excited states of “ mixed ” or “cross” (charge transfer) type, formed with participation of occupied molecular orbitals of one chromophoric fragment and vacant molecular orbitals of another, is typical of such a bichromophoric system. On the basis of our experimental and theoretical data, the assumption was made that the fluorescence quenching in the investigated bichromophoric molecules could be connected with the thermal population of the excited states of “mixed” type.

Synthesis of (R,R) and (S,S) bicyclo[3.3.0]octane-2,6-dione interactions between non-conjugated chromophores

Optically pure bicyclo[3.3.0]octane-2,6-dione is easily obtained with a yield of 4% for each enantiomer from 1,5-cyclooctadiene in 5 steps, by resolution of the intermediate diol with menthyloxyacetic acid. Its CD is 60% larger than twice the CD of a corresponding monoketone indicating interactions between non-conjugated chromophores.

Spectroscopic manifestation of association of biscyanine dyes with nonconjugated chromophores in low polarity solvents

Spectroscopic manifestation of association of biscyanine dyes with nonconjugated chromophores in low polarity solvents

ChemInform Abstract: Interaction Between Non‐Conjugated Chromophores. Part 29. Circular Dichroism of Planar, Exocyclic s‐cis‐Butadienes Remotely Perturbed

ChemInformVolume 19, Issue 24 Physical Organic Chemistry ChemInform Abstract: Interaction Between Non-Conjugated Chromophores. Part 29. Circular Dichroism of Planar, Exocyclic s-cis-Butadienes Remotely Perturbed Z. ZOU, Z. ZOU Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this authorL. SCHWAGER, L. SCHWAGER Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this authorP.-A. CARRUPT, P.-A. CARRUPT Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this authorP. VOGEL, P. VOGEL Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this author Z. ZOU, Z. ZOU Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this authorL. SCHWAGER, L. SCHWAGER Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this authorP.-A. CARRUPT, P.-A. CARRUPT Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this authorP. VOGEL, P. VOGEL Inst. chim. org., Univ., CH-1005 LausanneSearch for more papers by this author First published: June 14, 1988 https://doi.org/10.1002/chin.198824052Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume19, Issue24June 14, 1988 RelatedInformation

Characterization of Lignin in Situ by Photoacoustic Spectroscopy

Photoacoustic spectroscopy is a recently developed nondestructive analytical technique that provides ultraviolet, visible, and infrared absorption spectra from intensely light scattering, solid, and/or optically opaque materials not suitable for conventional spectrophotometric analysis. In wood and other lignocellulosics, the principal ultraviolet absorption bands, in the absence of photosynthetic pigments, arise from the aromatic lignin component of the cell walls. Photoacoustic spectra of extracted lignin fragments (milled wood lignin) and synthetic lignin-like polymers contain a single major absorption band at 280 nanometers with an absorption tail extending beyond 400 nanometers. Photoacoustic spectra of pine, maple, and oak lignin in situ contain a broad primary absorption band at 300 nanometers and a longer wavelength shoulder around 370 nanometers. Wheat lignin in situ, on the other hand, exhibits two principle absorption peaks, at 280 nanometers and 320 nanometers. The presence of absorption bands at wavelengths greater than 300 nanometers in intact lignin could result from (a) interacting, nonconjugated chromophores, or (b) the presence of more highly conjugated structural components formed as the result of oxidation of the polymer. Evidence for the latter comes from the observation that, on the outer surface of senescent, field-dried wheat culms (stems), new absorption bands in the 350 to 400 nanometer region predominate. These new bands are less apparent on the outer surface of presenescent wheat culms and are virtually absent on the inner surface of either senescent or presenescent culms, suggesting that the appearance of longer wavelength absorption bands in senescent wheat is the result of accumulated photochemical modifications of the ligin polymer. These studies also demonstrate photoacoustic spectroscopy to be an important new tool for the investigation of insoluble plant components.

Fluorescence characteristics of compounds containing nonconjugated chromophores with common aromatic ring

Fluorescence characteristics of compounds containing nonconjugated chromophores with common aromatic ring

Electronic Energy Transfer between Non-conjugated Chromophores

MODEL compounds incorporating inflexible, insulating nor-bornane frames to hold donor and acceptor chromophores with a fixed separation distance and orientation have proved useful in energy transfer studies1–10. We report the investigation of two new sets of such compounds. Each set consists of donor and acceptor chromophores held: (a) 7.5 A apart by a single-bridged norbornane frame; and (b) 10 A apart by a double-bridged exo-endo-1,4 : 5,8-dimethano-1,2,3,4,4a,5,6,7,8, 8a-decahydronaphthalene frame. For reference purposes, model compounds containing each individual donor and acceptor chromophore on a single-bridged frame were also prepared.

Excited state interactions between nonconjugated chromophores. Unusual polar photochemical methanol additions and reductions in the 1,3-diarylpropene system

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExcited state interactions between nonconjugated chromophores. Unusual polar photochemical methanol additions and reductions in the 1,3-diarylpropene systemStephen S. HixsonCite this: J. Am. Chem. Soc. 1972, 94, 7, 2505–2507Publication Date (Print):April 1, 1972Publication History Published online1 May 2002Published inissue 1 April 1972https://doi.org/10.1021/ja00762a052RIGHTS & PERMISSIONSArticle Views35Altmetric-Citations11LEARN 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 (396 KB) Get e-Alerts Get e-Alerts

Photochemical detection of intramolecular energy transfer between nonconjugated chromophores in rigid model compounds

Irradiation of the 4,5-benzotetracyclo[6,3,1,02,7,09,11]dodecane-10-spiro-9′-fluorene-3,6-dione (III) with light absorbed only by the tetralindione chromophore led to rearrangement of the fluorenespirocyclopropane system to dibenzofulvene. The photorearrangement of the ‘isolated’ acceptor chromophore, the tricyclo[3,2,1,02,4]-octane-3-spiro-9′-fluorene (V), to 2-(fluornen-9-ylidene)bicyclo[2,2,1]heptane was studied separately by direct and sensitized excitation. The photochemical quantum yield of the intramoleculary sensitized reaction in (III) was comparable to that of the intermolecularly sensitized photoisomerization of (V). This is consistent with an efficient energy transfer from the n,π* triplet of the ketone to the lowest π,π* triplet of fluorene in model compound (III). The fluorenespirocyclopropane system is well suited for use as acceptor in model compounds, having nonconjugated donor and acceptor chromophores inflexibly connected to the same molecular frame. The energy transfer efficiency in such compounds can be evaluated quantitatively from the extent of acceptor rearrangement on selective excitation of the donor. The mechanism of the photoisomerization is discussed.

Interaction of nonconjugated chromophores in rigid model compounds

Spectroscopic techniques and photochemistry were used to evaluate the interaction between an electronically excited chromophore and a different one in its ground state in rigid model compounds. These inflexible compounds are better suited for transfer work than binary mixed solutions of donor and acceptor since both the separation distance and the mutual orientation of the two chromophores are known, and complicating factors such as intermolecular transfer and complex formation are excluded by work at high dilution. Phenanthrene (P) and p-dimethoxybenzene (D) were rigidly connected to an inert spirocyclopropane-norbornane σ-frame. The S1 → S0 and T1 → S0 emissions of the two chromophores are found at different wavelengths and therefore can be detected separately. The emission and excitation spectra of the model compound were compared to those of an equivalent one-to-one mixture of each chromophore rigidly attached to the same inert frame. The dilute mixture shows the fluorescence and phosphorescence of each of the two components. In the model compound, however, the D fluorescence is definitely absent. The mechanism is consistent with efficient singlet energy transfer from the selectively excited D to P combined with partial back transfer from the T2 state of P to the lowest triplet of D.

Intramolecular triplet-triplet energy transfer between nonconjugated chromophores with fixed orientation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntramolecular triplet-triplet energy transfer between nonconjugated chromophores with fixed orientationNicolae Filipescu, John R. DeMember, and Fredrick L. MinnCite this: J. Am. Chem. Soc. 1969, 91, 15, 4169–4173Publication Date (Print):July 1, 1969Publication History Published online1 May 2002Published inissue 1 July 1969https://doi.org/10.1021/ja01043a026RIGHTS & PERMISSIONSArticle Views70Altmetric-Citations25LEARN 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 (601 KB) Get e-Alerts Get e-Alerts

Cage formation subsequent to intramolecular triplet-energy transfer

Although most work on intramolecular energy-transfer between nonconjugated chromophores has relied on measurements of donor and/or acceptor emission, it is evident that by proper choice of molecular system, a photochemical reaction of the acceptor could replace its emission. In the Diels–Alder adduct of 1,4-naphthoquinone with cyclopentadiene, the donor tetralin-1,4-dione (D) has been shown to transfer intramolecularly its lowest triplet energy to the isolated norbornylene double bond (N). Following energy migration, the excited olefinic acceptor attacks the π-system of the benzene nucleus in (D) to form a cage product by intramolecular cycloaddition. Sensitization experiments, control reactions, and low-temperature emission spectra verified the path followed by the excitation energy. Apparently the mechanism requires a change in steric conformation prior to cage formation. The intramolecular photochemical cycloaddition in the analogous p-benzoquinone–cyclopentadiene adduct is also discussed.

Intramolecular energy transfer between nonconjugated chromophores. Effect of rigid perpendicular orientation

Intramolecular energy transfer between nonconjugated chromophores. Effect of rigid perpendicular orientation

Intramolecular Electronic Energy Transfer between Nonconjugated Chromophores in Some Model Compounds

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntramolecular Electronic Energy Transfer between Nonconjugated Chromophores in Some Model CompoundsAngelo A. Lamola, Peter A. Leermakers, Gary W. Byers, and George S. HammondCite this: J. Am. Chem. Soc. 1965, 87, 11, 2322–2332Publication Date (Print):June 1, 1965Publication History Published online1 May 2002Published inissue 1 June 1965https://doi.org/10.1021/ja01089a004RIGHTS & PERMISSIONSArticle Views211Altmetric-Citations79LEARN 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 (1 MB) Get e-Alerts Get e-Alerts

Optical Rotatory Dispersion Associated with Dissymmetric Non-conjugated Chromophores. An Extension of the Octant Rule1-3

<b>Optical Rotatory Dispersion Associated with Dissymmetric Non-conjugated Chromophores. An Extension of the Octant Rule</b>^1-3