Photophysical characterization of trans-4,4′-disubstituted stilbenes

Papper, Vladislav; Pines, Dina; Likhtenshtein, Gertz I.; Pines, Ehud

doi:10.1016/s1010-6030(97)00234-7

Cited by 92 publications

(84 citation statements)

References 32 publications

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“…(B) Close-up view of the terminal groups of NT1 diene chromophore and NS1stilbene chromophore in nNOS red ; FAD is omitted for clarity (12)(13)(14). moiety were similar, with a maximum similar to the related 4-N, N-dimethylamino-4′-nitrostilbene (16,18). NS1 had an absorption maximum at λ max ¼ 460 nm with an extinction coefficient ε ¼ 21;000 M −1 cm −1 in DMSO (SI Appendix , Fig.…”

Section: Resultsmentioning

confidence: 99%

Rational design of a fluorescent NADPH derivative imaging constitutive nitric-oxide synthases upon two-photon excitation

Wang

Tarus

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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We report the structure-based design and synthesis of a unique NOS inhibitor, called nanoshutter NS1, with two-photon absorption properties. NS1 targets the NADPH site of NOS by a nucleotide moiety mimicking NADPH linked to a conjugated push-pull chromophore with nonlinear absorption properties. Because NS1 could not provide reducing equivalents to the protein and competed with NADPH binding, it efficiently inhibited NOS catalysis. NS1 became fluorescent once bound to NOS with an excellent signalto-noise ratio because of two-photon excitation avoiding interference from the flavin-autofluorescence and because free NS1 was not fluorescent in aqueous solutions. NS1 fluorescence enhancement was selective for constitutive NOS in vitro, in particular for endothelial NOS (eNOS). Molecular dynamics simulations suggested that two variable residues among NOS isoforms induced differences in binding of NS1 and in local solvation around NS1 nitro group, consistent with changes of NS1 fluorescence yield. NS1 colocalized with eNOS in living human umbilical vein endothelial cells. Thus, NS1 constitutes a unique class of eNOS probe with two-photon excitation in the 800-950-nm range, with great perspectives for eNOS imaging in living tissues.chemical biology | inhibition of enzymatic catalysis | structure-based design and molecular modeling | two-photon fluorescence imaging | fluorescence spectroscopy I n mammals, NO is a gaseous signaling mediator that exerts a wide range of key physiological functions, including blood pressure regulation, neurotransmission, and immune responses (1). NO is formed by nitric-oxide synthases, a family of hemoproteins that catalyzes the oxidation of L-arginine leading to L-citrulline and NO (2, 3). NOS catalysis is driven by reducing equivalents supplied by NADPH. NOS enzymes are constituted by oxygenase and reductase domains linked by a calmodulin (CaM)-binding domain. The oxygenase domain binds the heme, L-arginine, and the cofactor (6R)-5,6,7,8-tetrahydro-L-biopterin (H 4 B). The reductase domain binds two flavins, FMN and FAD, and NADPH (4). CaM binding allows the electron transfer from FMN to the heme (2, 3). The biological activities of NO are closely linked to the specific NOS isoform involved in its synthesis and deregulation of its biosynthesis leads to various pathologies (5). Data support the notion that inhibition of the inducible and neuronal isoforms iNOS and nNOS have therapeutic utility in the treatment of a variety of diseases, including septic shock, neurodegeneration, inflammation, and cancer (5, 6). It was shown that the endothelial isoform eNOS participates in tumor initiation and maintenance, thus its inhibition could be beneficial in this context (7,8). Based on crystallographic studies (9, 10), much effort was dedicated to the development of specific NOS inhibitors by targeting the heme site. However, most of these inhibitors are not specific and cannot avoid NOS uncoupling and formation of deleterious radical oxygen species (ROS) at the reductase domain. Although the struct...

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Section: Resultsmentioning

confidence: 99%

Rational design of a fluorescent NADPH derivative imaging constitutive nitric-oxide synthases upon two-photon excitation

Wang

Tarus

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…The excited state behaviour of 4,4Ј-substituted organic stilbenes has been studied intensively. [8,[80][81][82][83][84][85][86] For the excited state of the molecule, a three-state kinetic scheme is suggested (Scheme 4). [86] The ground state molecule (E) can be excited into the emissive state E* (planar geometry) in which the molecule is suggested to have biradicaloid character.…”

Section: Polarity Increases From Left To Right; Diethyl Ether (A) Etmentioning

confidence: 99%

“…A well-known example of such a push-pull conjugated system is trans 4-dimethylamino-4Ј-nitrostilbene (DANS), [4] a member of the trans 4,4Ј-disubstituted stilbene family (Scheme 1), which has been studied predominantly for its special photophysical and NLO properties. [5][6][7][8] Currently, conjugated systems containing transition metals attract much attention, [9][10][11][12][13] especially because the optoelectronic properties of these systems can be affected by changing the metal ion, the coordinating anions and ligands or by changing the nature of the connecting conjugated system. Interesting examples of metal-organic conjugated molecules studied for their NLO properties are the ferrocene-functionalized donor-acceptor complexes reported by McCleverty and coworkers.…”

Section: Introductionmentioning

confidence: 99%

Luminescent and Electronic Properties of Stilbenoid NCN‐Pincer Pt^II Compounds

et al. 2007

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A series of novel 4,4Ј-disubstituted organic-organometallic stilbenes were synthesized, that is, the 4Ј-substituted stil--in which R = C 2 H 2 C 6 H 4 -RЈ-4Ј with RЈ = NMe 2 , OMe, SiMe 3 , H, I, CN, NO 2 ) (1-7). In these compounds the PtCl grouping can be considered to be present as a donor substituent. Their synthesis involved a Horner-Wadsworth-Emmons reaction of [PtCl(NCN-CHO-4)] (9) with the appropriate phosphonate ester derivatives (8a-g). Under these reaction conditions, the C-Pt bond in aldehyde 9 was not affected, and the platinated stilbene products were obtained in 53-90 % yield. The solidstate structures of complexes 1, 2 and 5-7 were determined by single-crystal X-ray diffraction, which revealed interesting bent conformations for 2, 5 and 7. Linear correlations were found between both the 13 C{ 1 H} (C ipso to Pt) and the

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“…Indeed, the rates of some reactions in the excited state for a series of molecules differing in substituents could be correlated with the Hammett constants of the substituents, which were derived for reactions proceeding in the ground state. Of the rich array of photochemical phenomena one can mention the reaction of photoisomerization of 4,4 0 -disubstituted stilbenes [10] as well as their photochemical characterization [11] which have been studied from the point of view of the impact of substituents on excited state processes. It was shown that for the compounds fluorescence quantum yield U and lifetime s f were mainly determined by the cis-trans photoisomerization rate and about a half of the log(1/s f ) and log U data points (in different solvents) show a linear dependence on (r X -r Y ), where X and Y are substituents at 4 and 4 0 positions, and r X , r Y -the Hammett constants for substituents in the para position to a functional group in benzene ring, generally known as r p .…”

Section: Introductionmentioning

confidence: 99%

Excited state substituent constants: to Hammett or not?

Sadlej-Sosnowska

Kijak

2011

Struct Chem

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In this study, an answer has been sought to several questions: Can substituents' impact on the electronic properties of molecules in the excited singlet states be summed up by a set of substituent constants? Are the well known, ground state Hammett r constants practical for this purpose? To answer these questions, the potentials and charges on atoms of the functional groups in two classes of compounds, p-substituted benzoic acids and p-substituted nitrosobenzenes, were regressed against r p . It appeared that all correlations found in the ground state of the molecules also hold in the excited state, with lower correlation coefficients in the latter. An attempt has also been made to find a molecular characteristic which could be useful in a comparison of the acidic properties of benzoic acids (in gas phase) in the first excited and ground states.

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Photophysical characterization of trans-4,4′-disubstituted stilbenes

Cited by 92 publications

References 32 publications

Rational design of a fluorescent NADPH derivative imaging constitutive nitric-oxide synthases upon two-photon excitation

Rational design of a fluorescent NADPH derivative imaging constitutive nitric-oxide synthases upon two-photon excitation

Luminescent and Electronic Properties of Stilbenoid NCN‐Pincer Pt^II Compounds

Excited state substituent constants: to Hammett or not?

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Photophysical characterization of trans-4,4′-disubstituted stilbenes

Cited by 92 publications

References 32 publications

Rational design of a fluorescent NADPH derivative imaging constitutive nitric-oxide synthases upon two-photon excitation

Rational design of a fluorescent NADPH derivative imaging constitutive nitric-oxide synthases upon two-photon excitation

Luminescent and Electronic Properties of Stilbenoid NCN‐Pincer PtII Compounds

Excited state substituent constants: to Hammett or not?

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Luminescent and Electronic Properties of Stilbenoid NCN‐Pincer Pt^II Compounds