Influence of the electron donor groups on the optical and electrochemical properties of borondifluoride complexes of curcuminoid derivatives: a joint theoretical and experimental study

Canard, Gabriel; Ponce-Vargas, Miguel; Jacquemin, Denis; Guennic, Boris Le; Felouat, Abdellah; Rivoal, Morgane; Zaborova, Elena; D’Aléo, Anthony; Fagès, Frédéric

doi:10.1039/c6ra25436e

Cited by 28 publications

(21 citation statements)

References 48 publications

(44 reference statements)

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“…The cyclic voltammograms (CVs) of the five compounds were recorded in DCMc ontaining 0.1 m of (nBu) 4 NPF 6 and display two-electron irreversible oxidation and reduction wavesc onsistent with the electrochemical properties of curcuminoids-BF 2 ( Figure S2). [23] The oxidation and reduction half-wavep otential values (Table S1) are very close to those obtained fort he reference compounds,s howingt hat tethering two curcuminoid-BF 2 units does not change significantly their electrochemical behavior in solution.…”

Section: Synthesis and Electrochemical Propertiessupporting

confidence: 71%

Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF₂ Dimers

Catherin

Uranga-Barandiaran

Brosseau

et al. 2020

Chemistry A European J

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We describe the synthesis of a series of covalently linked dimers of quadrupolar curcuminoid‐BF2 dyes and the detailed investigation of their solvent‐dependent spectroscopic and photophysical properties. In solvents of low polarity, intramolecular folding induces the formation of aggregated chromophores, the UV/Vis absorption spectra of which display the optical signature characteristic of weakly‐coupled H‐aggregates. The extent of folding and, in turn, of ground‐state aggregation is strongly dependent on the nature of the flexible linker. Steady‐state and time‐resolved fluorescence emission spectroscopies show that the Frenkel exciton relaxes into a fluorescent symmetrical excimer state with a long lifetime. Furthermore, our in‐depth studies show that a weakly emitting excimer lies on the pathway toward a photocyclomer. Two‐dimensional 1H NMR spectroscopy and density functional theory (DFT) allowed the structure of the photoproduct to be established. To our knowledge, this represents the first example of a [2π+2π] photodimerization of the curcuminoid chromophore.

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Section: Synthesis and Electrochemical Propertiessupporting

confidence: 71%

Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF₂ Dimers

Catherin

Uranga-Barandiaran

Brosseau

et al. 2020

Chemistry A European J

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“…However, the difluoroboron complex of acetylacetone provides a pathway to dyes with the dioxaborine core incorporated into the polymethine chain as the central electron acceptor group of the D–π–A–π–D system. Only bis‐styryls of this type ― borondifluoride complexes of curcumin analogues ― have been reported hitherto (Figure ) . Their absorption maximum ranges from 450 to 650 nm, shifting bathochromically and gaining intensity with increasing electron‐donating ability of a substituent in the benzene rings , .…”

Section: Introductionmentioning

confidence: 99%

“…Their absorption maximum ranges from 450 to 650 nm, shifting bathochromically and gaining intensity with increasing electron‐donating ability of a substituent in the benzene rings , . Their photophysical, NLO, and electrochemical properties were studied in detail by a group of French scientists . The NIR emission of difluoroborinated curcuminoids makes them suitable candidates for NIR imaging, which has attracted considerable attention because it allows deep tissue penetration, shows low auto‐fluorescence background, and causes less damage to biological samples.…”

Section: Introductionmentioning

confidence: 99%

D–π–A–π–D Dyes with a 1,3,2‐Dioxaborine Cycle in the Polymethine Chain: Efficient Long‐Wavelength Fluorophores

et al. 2018

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The nitrile group in newly synthesized 5‐cyano‐2,2‐difluoro‐4,6‐dimethyl‐1,3,2‐dioxaborine is shown to significantly increase the acidity of the methyl groups. This allows the cyanine condensation with both methyl groups to form D–π–A–π–D dyes in which the dioxaborine cycle is a part of the polymethine chain. There, the reactivity of the remaining methyl group in the semi‐product is reduced enough to perform the reaction stepwise, giving access to nonsymmetric derivatives. The synthesis of dyes with various electron donor termini [indole, benzothiazole, pyran, 4‐(dialkylamino)phenyl] and with different polymethine chain lengths is reported. The obtained compounds show intense absorption and fluorescence in the red and NIR region, their fluorescence brightness (the product of the molar extinction and the fluorescence quantum yield) attaining a value of 200,000 m–1 cm–1. They are characterized by small‐scale positive solvatochromism, yet their fluorescence quantum yield is much more sensitive to ambient polarity. Time‐dependent (TD)DFT calculations have been performed to study the electronic structure of the new dioxaborines and reveal the nature of the long‐wavelength electronic transitions in those molecules.

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“…Nevertheless, we test three protocols here, in order to pinpoint the best option for the investigated dyes. We can classify the studied systems as: curcuminoids (1) 40 , characterized by two donor groups attached to a dioxaborine moiety through π-conjugated chains, hemicurcuminoids (2) 41,42 , with one donor group connected to the dioxaborine fragment by a π-connector while the other one is linked through a single bond; their ethynylene analogues (3) 41 , and 2'-hydroxy-chalcones (4) [43][44][45] . In Scheme 2, we can observe the complete panel of borondifluoride β-diketonate complexes studied in the first stage of this work.…”

Section: Assessment Of the Theoretical Approachesmentioning

confidence: 99%

“…Herein we perform a detailed TD-DFT study of the relationships between absorption/emission properties and structural features of a large set of borondifluoride βdiketonate complexes based on four families of dyes: curcuminoids 40 , hemicurcuminoids 41,42 , their ethynylene analogues 41 and 2'-hydroxy-chalcones (Scheme 2) [43][44][45] . As a first step, we…”

Section: Introductionmentioning

confidence: 99%

Searching for new borondifluoride β -diketonate complexes with enhanced absorption/emission properties using ab initio tools

et al. 2018

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The rational design of fluorophores with enhanced absorption/emission properties increasingly relies on theoretical chemistry, as new ab initio methods suited for electronically excited-states reduce the gap between calculated and experimental results. In this framework, Time-Dependent Density Functional Theory (TD-DFT) emerges as an attractive option as it often provides accurate results at a moderate computational cost. Here, we perform a TD-DFT-SOS-CIS(D) study of a panel of 18 borondifluoride β-diketonate complexes that can be classified as: curcuminoids, hemicurcuminoids, their ethynylene analogues, and 2'-hydroxychalcones. First, we reproduce the experimental 0-0 energies with refined models considering the impact of vibrational and solvent effects, the latter through both linear response and twostate specific approaches. We also evaluate the impact of double excitations by using the SOS-CIS(D) scheme to correct the TD-DFT estimates. In addition, we carry out a vibronic simulation for a representative system. Next, we analyze the obtained key structure-property relationships leading to pronounced bathochromic shifts, and finally, based on the obtained results, we propose a panel of related compounds looking for systems with absorption and emission maxima located at longer wavelengths.A-π-D molecules. As a consequence, the lowest-energy absorption and emission bands display a significant intramolecular charge transfer (CT) character 16,21 which allows a fine tuning of the optical properties, depending on the strength of the donor group, e.g., the absorption and emission maxima are redshifted when strong pushing groups are used 22 . In addition, a wide gap between absorption and emission maxima, that is a large Stokes shift, is desired for many practical applications, as it allows to reduce losses arising from selfabsorption 23 . Among the different strategies used to induce both bathochromic shifts and enhanced Stokes shifts, the incorporation of electron donor groups 24-26 and the extension of the π-conjugation path 27-29 have proven to be particularly effective.A key parameter in the theoretical study of all dyes is the 0-0 Energy ( ) that can be defined as the difference between the excited state (ES) and ground state (GS) energies calculate the AFCP values by using an adiabatic TD-DFT protocol, taking into account solvent effects through a refined PCM model, and accounting for double excitations through the SOS-CIS(D) approach. Additionally, we carried out a vibronic analysis within the Franck-Condon approximation, and we use electronic density difference (EDD) maps and charge-an approach well suited for local ES. On the other hand, one can select one of the State-Specific (SS) formalism, that use the one-particle density matrix to correct the gas-phase transition energies, a scheme suited for CT ES. Two SS models are available in Gaussian: the iterative one of Improta and co-workers 53 , simply referred to as "SS" in the following, and the perturbative corrected Linear Response (cLR) 54 method of Mennuc...

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Influence of the electron donor groups on the optical and electrochemical properties of borondifluoride complexes of curcuminoid derivatives: a joint theoretical and experimental study

Cited by 28 publications

References 48 publications

Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF₂ Dimers

Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF₂ Dimers

D–π–A–π–D Dyes with a 1,3,2‐Dioxaborine Cycle in the Polymethine Chain: Efficient Long‐Wavelength Fluorophores

Searching for new borondifluoride β -diketonate complexes with enhanced absorption/emission properties using ab initio tools

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Influence of the electron donor groups on the optical and electrochemical properties of borondifluoride complexes of curcuminoid derivatives: a joint theoretical and experimental study

Cited by 28 publications

References 48 publications

Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF2 Dimers

Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF2 Dimers

D–π–A–π–D Dyes with a 1,3,2‐Dioxaborine Cycle in the Polymethine Chain: Efficient Long‐Wavelength Fluorophores

Searching for new borondifluoride β -diketonate complexes with enhanced absorption/emission properties using ab initio tools

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Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF₂ Dimers

Exciton Interactions, Excimer Formation, and [2π+2π] Photodimerization in Nonconjugated Curcuminoid‐BF₂ Dimers