Semi-empirical AM1 and PM3 molecular orbital calculations on the mechanism of the hydrolysis of unsaturated lactones: substituted (E )-5,5′-diphenylbifuranylidenediones and 3,7-diphenylpyrano[4,3-c]pyran-1,5-diones

Bowden, Keith; Fabian, Walter M. F.; Kollenz, G.

doi:10.1039/a606098f

Cited by 12 publications

(4 citation statements)

References 33 publications

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“…The conjugated polymer 1 depicted in Figure 1 was synthesized by the organometallic palladium route. 29 The other structure (2) in the same figure was also synthesized, but it was only used as a theoretical procedure to reduce computational costs because, for alkoxy compounds, the length of the lateral chain bonded to oxygen does not interfere in the electronic properties of the conjugated backbone, as reported elsewhere, 57 and was confirmed by optical absorption (OA) measurements. 58 But this length does interfere with the semicrystalline solid state structure given by the lamellar phases induced by the interdigitation of the lateral branch chains.…”

Section: Methodsmentioning

confidence: 99%

Controlling Bandgap Energy and Multivibronic Modes of a Poly(2,5-thiophene-1,4-dialkoxyphenylene) Derivative by Gamma Photons

et al. 2011

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In this work, the influence of γ radiation on electronic, structural, and vibrational properties of a poly(2,5-thiophene-1,4-dialkoxyphenylene) derivative is studied by optical absorption and photoluminescence. A Gaussian fit of emission spectra within Franck-Condon vertical transitions formalism was carried out in order to understand how vibronic coupling is affected by the dose, because an unexpected luminescence behavior was observed. Aiming to understand the ionizing radiation-matter interaction processes, we employed a molecular modeling procedure, through the use of a semiempirical method (AM1) applied to conjugated oligomers' conformational structure and equilibrium geometries, to clarify the defects induction for the used doses. From AM1 optimized structures, electronic transitions were calculated by ZINDO/S-CI semiempirical method to measure the chain scission degree. Moreover, with the results presented in this work, it is possible to come up with a new physical-chemical route to treat and increase conjugated polymers' efficiency. Finally, we believe that the present paper contributes to the literature about defects on conjugated polymers.

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Section: Methodsmentioning

confidence: 99%

Controlling Bandgap Energy and Multivibronic Modes of a Poly(2,5-thiophene-1,4-dialkoxyphenylene) Derivative by Gamma Photons

et al. 2011

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“…[10,11] On the other hand, Pechmann dye can be thermally rearranged in protic solvents or under basic conditions to an endo-fused six-membered lactone dimer (rearranged Pechmann lactone, RPLN, IV) with a concomitant colour change from red to yellow. [12] Both lactones are fluorescent (in yellow and green, respectively) in nonpolar solvents. In contrast, amidation of IV to endofused mono-and dilactams (rearranged Pechmann lactamlactone, RPLMN, V and rearranged Pechmann lactam, RPLM, VI, respectively) is accompanied by a blueshift.…”

Section: Introductionmentioning

confidence: 99%

Thiophene‐Containing Pechmann Dyes and Related Compounds: Synthesis, and Experimental and DFT Characterisation

Kantchev

Norsten

Tan

et al. 2011

Chemistry A European J

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Attaching 2-thienyl residues to the Pechmann dye core chromophore (5,5-exo-dilactone situated around a C-C double bond) results in a novel magenta-coloured compound (UV/Vis spectroscopy λ(max) =570 nm in CHCl(3)), which can be rearranged to a yellow 6,6-endo-dilactone (λ(max) =462 nm in CHCl(3)). Single and double amidation results in pronounced redshift in the 5,5-exo series (violet, λ(max) =570 nm and blue, λ(max) =606 nm in CHCl(3), respectively) but pronounced blueshift in the 6,6-endo series (yellow, λ(max) =424 nm and pale yellow bordering on colourless, λ(max) =395 nm in CHCl(3), respectively). Incorporation of a 3-alkyl substituent on the thiophene ring allows for sharp increase of solubility in organic solvents concomitant with fine-tuning of the colour: a redshift in 5,5-exo-dilactones but a blueshift in 5,5-exo-dilactams. DFT computations demonstrate that both lactone classes are planar regardless of the presence of a 3-alkyl group. The lactam derivatives are non-planar: the thiophene-core chromophore dihedral angles increase on going from 5,5-exo to 6,6-endo and from thiophene to 3-alkyl thiophene. Depending on the core heteroatom (O vs. N-alkyl), ring junction (5,5-exo vs. 6,6-endo) and 3-thiophene substituent (H vs. alkyl), two, three, four or six conformers are possible. All of these conformers were characterised by DFT and were found to be very close in energy at both IEFPCM/B3LYP/DGDZVP and SMD/M06/DGDZVP levels of theory. Within each conformer set, the HOMO and LUMO energies were within 0.05 eV and the predicted λ(max) values (TD-DFT) within 10 nm, and this implies low sensitivity of the optical and electronic properties to conformation. Cyclic voltammetry measurements of selected compounds demonstrated good matching to the HOMO and LUMO energies from IEFPCM/B3LYP/DGDZVP computations. M06-2X was the best DFT functional for TD-DFT, giving predicted λ(max) values within about 20 nm.

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“…Such an approach has proved to give reliable results in related reactions. 3,21 Using H 2 O as a reagent implies that, besides addition to the carbonyl carbon, proton transfer to the oxygen atom is also necessary. Hence the activation energy for such a process will be considerably higher than that for a simple addition.…”

Section: Calculationsmentioning

confidence: 99%

Base-catalysed hydrolysis of ?-lactones: reactivity-structure correlations for 3-(substituted phenoxy- and thiophenoxymethylene)-(Z )-1(3H )-isobenzofuranones

Bowden

Ranson

Perjéssy

et al. 1998

J. Phys. Org. Chem.

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Rate coefficients were measured for the base-catalysed hydrolysis of a series of substituted 3-(phenoxyor thiophenoxymethylene)-(Z)-1(3H)-isobenzfuranones (3-phenoxy-or thiophenoxymethylenephthalides) in 70% (v/v) aqueous dioxane at 30.0°C, in addition to the carbonyl stretching frequencies in chloroform and tetrachloromethane following deconvolution and band separation, when required. The Hammett reaction constants for the alkaline hydrolysis of the 3-/4-substituted phenoxy and thiophenoxy series are ca 0.75 and 1.10, respectively. These results are related to electrostatic field and resonance effects. Successful correlations between the carbonyl stretching frequencies and substituent constants and the rates of alkaline hydrolysis were found. Computational studies using the semi-empirical AM1 method correctly model both the details of the mechanistic pathway and the substituent effects.

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Semi-empirical AM1 and PM3 molecular orbital calculations on the mechanism of the hydrolysis of unsaturated lactones: substituted (E )-5,5′-diphenylbifuranylidenediones and 3,7-diphenylpyrano[4,3-c]pyran-1,5-diones

Cited by 12 publications

References 33 publications

Controlling Bandgap Energy and Multivibronic Modes of a Poly(2,5-thiophene-1,4-dialkoxyphenylene) Derivative by Gamma Photons

Controlling Bandgap Energy and Multivibronic Modes of a Poly(2,5-thiophene-1,4-dialkoxyphenylene) Derivative by Gamma Photons

Thiophene‐Containing Pechmann Dyes and Related Compounds: Synthesis, and Experimental and DFT Characterisation

Base-catalysed hydrolysis of ?-lactones: reactivity-structure correlations for 3-(substituted phenoxy- and thiophenoxymethylene)-(Z )-1(3H )-isobenzofuranones

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