Vibronic absorption spectra of naturally occurring conjugated polyenynes. Evidence for localized excitations

Smulevich, Giulietta; Marzocchi, Mario P.; Vincieri, Franco Francesco; Coran, Silvia A.; Alberti, Massimo Bambagiotti

doi:10.1039/p29870001431

Cited by 5 publications

(4 citation statements)

References 3 publications

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“…9 The D 2 spectrum clearly reveals better resolution than the ABS spectrum. 36 The broad features in ABS due to the overlapping contribution of numerous weak fundamentals, overtones, and combinations are suppressed in the D 2 spectrum where the origin and the prominent vibrations are selectively enhanced. 22,37,38 The vibrational structure ͑Fig.…”

Section: 4-dihydroxyanthraquinone (14-dhaq)mentioning

confidence: 98%

Intramolecular hydrogen bonding and excited state proton transfer in hydroxyanthraquinones as studied by electronic spectra, resonance Raman scattering, and transform analysis

Marzocchi¹,

Mantini²,

Casu³

et al. 1998

The Journal of Chemical Physics

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The scheme of energy levels previously proposed to describe dual excitation and emission associated to excited state intramolecular proton transfer (ESIPT) of some hydroxyanthraquinones (HAQ’s) has been made more quantitative in the present paper. The zero-point energy and the frequency of the νOH mode for the HAQ’s have been calculated on the basis of the Lippincott–Schroeder double-minimum potential for the O–H⋯O hydrogen bond. The second derivative absorption (D2) spectra show that the vibrational structures of the electronic excited state of HAQ’s giving rise to ESIPT are characterized by the progression of the νOH stretching mode. The νOH mode in the ground state is observed as a very strong band in the vibrational structure of the short wavelength emission for HAQ’s showing ESIPT. The combined resonance Raman band assignment of four hydroxyanthraquinones and transform analysis show that the visible transition involves the hydrogen bonded cycle and induces proton transfer in the excited state in most cases. On the basis of the isotopic effects, some vibrations of the hydrogen bonded cycle, namely the νC=O, δC=O, νCOH, and δOH modes, have been identified. The transform method, including the combined analysis of the absorption and D2 spectra in terms of sum-over-states, was checked by directly deriving the displacement parameters (Franck–Condon factors) of 1,4-DHAQ from the high resolution free-jet spectrum. The values of the displacement parameters of the νOH mode are quite large for the HAQ’s showing ESIPT, while are negligible for 1,4-DHAQ. High values of the displacement parameters for the other vibrations of the hydrogen bonded cycle were found for all HAQ’s.

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Section: 4-dihydroxyanthraquinone (14-dhaq)mentioning

confidence: 98%

Intramolecular hydrogen bonding and excited state proton transfer in hydroxyanthraquinones as studied by electronic spectra, resonance Raman scattering, and transform analysis

Marzocchi¹,

Mantini²,

Casu³

et al. 1998

The Journal of Chemical Physics

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“…The second-derivative technique was also applied to a series of related naturally-occurring polyenynes, whose chromophoric fragments ranged from three to six conjugated groups. These results account for the structural characteristics, including steroisomerism, of a given sequence of triple and double bonds providing a complete fingerprint of the polyenyne chromophore [32]. In another paper, the application of the MS-MS technique for the rapid monitoring of some γ-butyrolactone ring and related lignans of O. aquatica fruits infusion was reported [33].…”

Section: S Telephium (Crassulaceae) (mentioning

confidence: 85%

1968–2008: 40 Years of Franco F. Vincieri's Natural Products Research

Bilia

2008

Natural Product Communications

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This paper presents an overview of Prof. Vincieri's accomplishments in his career as a researcher in the field of pharmacognosy (pharmaceutical biology), analytical phytochemistry and pharmaceutical technology applied to herbal drug preparations at the Department of Pharmaceutical Sciences of the University of Florence. This article is a recognition of his valuable contributions to these research fields, especially for his outstanding and innovative interdisciplinary studies on the quality control of herbal drugs, herbal drug preparations, herbal medicinal products, botanical food supplements, and some "special foods" such as grapes, wines, olives and olive oil.

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“… Unlike the 1 H NMR spectrum of Dipentyl-4 (Figure S29), that of 3MeCy-4 (Figures b and S24) exhibits resonance signal pairs at 6.65 and 6.53 ppm and 3.47 and 3.41 ppm that are assigned to the asymmetric olefinic (H A and H A′ ) and acetylenic (H B and H B′ ) protons, respectively. As is the case with the organotriflates, the UV/vis absorption spectra of the dienediyne comonomers (Figures S26 and S31) are nearly identical, each dominated by a narrow absorption band with a λ max at 319 nm ( 3MeCy-4 , ε = ∼11890; Dipentyl-4 , ε = ∼12680 (L mol –1 cm –1 )) and a low-energy shoulder at 332 nm that is ascribed to vibronic coupling phenomena that are common among polyenynes and polyynes. , …”

mentioning

confidence: 99%

“…As is the case with the organotriflates, the UV/vis absorption spectra of the dienediyne comonomers (Figures S26 and S31) are nearly identical, each dominated by a narrow absorption band with a λ max at 319 nm (3MeCy-4, ε = ∼11890; Dipentyl-4, ε = ∼12680 (L mol −1 cm −1 )) and a low-energy shoulder at 332 nm that is ascribed to vibronic coupling phenomena that are common among polyenynes and polyynes. 27,28 Use of the 5,5-substituted cyclopentadiene-based comonomers enabled room temperature Pd-catalyzed Sonogashira polycondensation polymerizations (Scheme 1a) to afford soluble dark purple solids after purification. The GPC chromatograms of 3MeCy-PCE and Dipentyl-PCE (Figures S33 and S34) are predominantly monomodal, showing number-average molecular weights M n of 25.1 kDa (Đ = 2.2, THF, polystyrene standards) and 5.4 kDa (Đ = 2.2, THF, polystyrene standards), respectively, suggesting that the sterically demanding pentyl groups impede carbon−carbon cross-coupling as a result of steric congestion around the catalyst center.…”

mentioning

confidence: 99%

Poly(cyclopentadienylene ethynylene)s: Breaking Conventional Polyenyne Motifs

et al. 2017

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Conjugated polyenynes comprising dienyne constituents have been synthesized for the first time, expanding the architectural scope of this unique polymer class. The poly(cyclopentadienylene ethynylene)s (PCE)s are soluble in common organic solvents, a rare feature among polyenynes, and possess physicochemical properties that are influenced by the structure of their solubilizing groups. A comparative analysis between the PCEs and other soluble polyenynes, poly(arylene ethynylene)s, and a hybrid of both polymer classes show among other characteristics that the inclusion of cyclopentadienes into the conjugated backbone significantly reduces electronic transition energies while completely suppressing photoluminescence.

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Vibronic absorption spectra of naturally occurring conjugated polyenynes. Evidence for localized excitations

Cited by 5 publications

References 3 publications

Intramolecular hydrogen bonding and excited state proton transfer in hydroxyanthraquinones as studied by electronic spectra, resonance Raman scattering, and transform analysis

Intramolecular hydrogen bonding and excited state proton transfer in hydroxyanthraquinones as studied by electronic spectra, resonance Raman scattering, and transform analysis

1968–2008: 40 Years of Franco F. Vincieri's Natural Products Research

Poly(cyclopentadienylene ethynylene)s: Breaking Conventional Polyenyne Motifs

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