Bis(pentafluorophenyl)-<i>o</i>-carborane and its arylthio derivatives: synthesis, electrochemistry and optical properties

Shida, Naoki; Owaki, Satoshi; Eguchi, Hiroshi; Nishikawa, Takanobu; Tomita, Ikuyoshi; Inagi, Shinsuke

doi:10.1039/d0dt02205e

Cited by 10 publications

(8 citation statements)

References 25 publications

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“…10−13 While it has been demonstrated that these scrambling reactions can be overcome through the use of direct carbon−carbon bonds, this strategy limits the use of other readily available substrates. 9,14,15 Previous work from our group and others suggests that this scrambling effect can be overcome through the development of substituted perfluoroaromatic monomers with the appropriate bond angles, such that reverse substitution reactions are disfavored. 10,11 By developing polymerizable-substituted perfluoroaromatic compounds with these properties, these systems could be readily utilized for the preparation of a variety of postmodified polymer architectures.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Yet, while many of these perfluoroaromatic systems are promising for the preparation of novel polymer architectures, these systems have displayed some drawbacks. Previous work from other groups as well as our own has demonstrated that perfluoroaromatics, such as perfluoropyridine, can demonstrate a high degree of chemical reversibility with heteroatom nucleophiles depending upon the structural nature of the nucleophile as well as the reaction conditions resulting in so-called “scrambling” reactions around the perfluoroaromatic ring. − While it has been demonstrated that these scrambling reactions can be overcome through the use of direct carbon–carbon bonds, this strategy limits the use of other readily available substrates. ,, Previous work from our group and others suggests that this scrambling effect can be overcome through the development of substituted perfluoroaromatic monomers with the appropriate bond angles, such that reverse substitution reactions are disfavored. , By developing polymerizable-substituted perfluoroaromatic compounds with these properties, these systems could be readily utilized for the preparation of a variety of postmodified polymer architectures. , …”

Section: Introductionmentioning

confidence: 99%

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Toward Taming the Chemical Reversibility of Perfluoropyridine through Molecular Design with Applications to Pre- and Postmodifiable Polymer Architectures

et al. 2021

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Polymer functionality greatly determines many of the key properties of these materials, such as glass-transition temperature, electrical and thermal conductivity, thermal stability, mechanical strength, and processability. Despite the importance of polymer functionality in determining material properties, the synthesis of functional polymers, with well-defined molecular weights and compositions, can still present a significant challenge, with many of the methods related to pre- or postpolymerization modification lacking synthetic scope, or requiring harsh functionalization conditions or transition-metal coupling reactions to install the desired functionality. Perfluoroaromatic systems are promising for the preparation of novel polymer architectures given that they can be readily functionalized using simple nucleophilic chemistries under very mild basic conditions. While promising, these systems have displayed some drawbacks. Previous work has shown that perfluoroaromatics, such as perfluoropyridine, can demonstrate a high degree of chemical reversibility with heteroatom nucleophiles. If the synthetic potential of these systems is to be realized, then a strategy for the rational design of stable monomers must be developed. Herein, we report the design, synthesis, and characterization of a series of unexplored heteroatom-based ring-opening metathesis polymerization (ROMP)-active monomers containing a reactive perfluoropyridine pendent group, which can be used to readily prepare a wide variety of aryl ether-functionalized polymers, using both pre- and postpolymerization modification strategies. We also establish a direct connection between the dihedral angle of the monomer and its propensity to undergo reversible addition reactions, establishing functional criteria for the design of pre- and postmodifiable systems.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Toward Taming the Chemical Reversibility of Perfluoropyridine through Molecular Design with Applications to Pre- and Postmodifiable Polymer Architectures

et al. 2021

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“…It should also be noted that fluorescence quenching through the CT state may not be the sole mechanism for o -CB–fluorophore systems where a parallel conformation between the C 1 –C 2 bond and fluorophores (φ = 0°) is structurally prohibited such as the cases of disubstituted o -CBs. 26 , 69 , 79 In these cases, other mechanisms such as photoinduced electron transfer between two fluorophores are more likely for fluorescence quenching.…”

Section: Resultsmentioning

confidence: 99%

“…Different functionals [BP86 , (GGA), B3LYP (hybrid), CAM-B3LYP (range-separated), and M06-2X (meta-hybrid)] were employed for the TDDFT optimization of three main excited-state conformations for benchmarking purposes. We note that B3LYP has been widely preferred for the excited-state investigation of o -CB– Ant as well as other carborane–fluorophore systems. ,− ,,,,− In general, this functional shows good agreement for the absorption and emission energies of these systems. However, one should also note that it can sometimes be problematic for pure CT states as it is shown to underestimate the excited-state energies for such transitions. − In Tables S1–S3 and Figure S3, we compare the results of our benchmark calculations.…”

Section: Methodsmentioning

confidence: 92%

Revisiting the Role of Charge Transfer in the Emission Properties of Carborane–Fluorophore Systems: A TDDFT Investigation

2022

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In this study, we performed a detailed investigation of the S 1 potential energy surface (PES) of o -carborane–anthracene ( o -CB– Ant ) with respect to the C–C bond length on o -CB and the dihedral angle between o -CB and Ant moieties. The effects of different substituents (F, Cl, CN, and OH) on carbon- or boron-substituted o -CB, along with a π-extended acene-based fluorophore, pentacene, on the nature and energetics of S 1 → S 0 transitions are evaluated. Our results show the presence of a non-emissive S 1 state with an almost pure charge transfer (CT) character for all systems as a result of significant C–C bond elongation (C–C = 2.50–2.56 Å) on o -CB. In the case of unsubstituted o -CB– Ant , the adiabatic energy of this CT state corresponds to the global minimum on the S 1 PES, which suggests that the CT state could be involved in emission quenching. Despite large deformations on the o -CB geometry, predicted energy barriers are quite reasonable (0.3–0.4 eV), and the C–C bond elongation can even occur without a noticeable energy penalty for certain conformations. With substitution, it is shown that the dark CT state becomes even more energetically favorable when the substituent shows −M effects (e.g., −CN), whereas substituents showing +M effects (e.g., −OH) can result in an energy increase for the CT state, especially for partially stretched C–C bond lengths. It is also shown that the relative energy of the CT state on the PES depends strongly on the LUMO level of the fluorophore as this state is found to be energetically less favorable compared to other conformations when anthracene is replaced with π-extended pentacene. To our knowledge, this study shows a unique example of a detailed theoretical analysis on the PES of the S 1 state in o -CB– fluorophore systems with respect to substituents or fluorophore energy levels. Our findings could guide future experimental work in emissive o -CB– fluorophore systems and their sensing/optoelectronic applications.

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“…Therefore, many types of the aryl-modified o-carborane dyads exhibit the aggregation-induced emission (AIE) property. [27,[44][45][46][47][48][49][50] Correspondingly, intense emission was observed around 400 nm in solution thio-CBH, meanwhile significant emission band around 650 nm was obtained in aggregation and crystal. From the solvatochromic behavior (Figures S2 and S3 and Table S2) and longer lifetimes, it was suggested that the emission band in the longer wavelength region should be obtained from the ICT state.…”

Section: Resultsmentioning

confidence: 99%

Rational design for thermochromic luminescence in amorphous polystyrene films with bis‐o‐carborane‐substituted enhanced conjugated molecule having aggregation‐induced luminochromism

et al. 2021

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We designed the triad molecule, bis-o-carborane-substituted bis(thienylethynyl) benzene, as a filler for realizing thermochromic luminescent behaviors based on conventional polymer films, such as polystyrene. From the optical measurements, it was found that the triad can show solid-state emission and dual-luminescent properties with variable intensity ratios depending on media. From the mechanistic studies including the experiments with the methyl-substituted model compound, it was revealed that dual emission should be originated from the locally excited and twisted intramolecular charge transfer states, and the latter emission band is significantly enhanced in the solid states. We prepared amorphous films containing variable concentrations of the triad with the spin-coating method and investigated optical properties. It was found that intensity ratios were drastically changed by altering the concentration of the triad. By increasing the proportion of the triad, aggregation occurred, and emission color was apparently varied through the changes in intensity ratios of the dual emission property. Based on the aggregationinduced luminochromic property of the triad, thermochromic luminescence was finally realized by heating the amorphous films. The rational design for obtaining thermochromic luminescent amorphous films is illustrated in this paper.

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Bis(pentafluorophenyl)-o-carborane and its arylthio derivatives: synthesis, electrochemistry and optical properties

Abstract: The synthesis of bis(pentafluorophenyl)-o-carborane is reported, which is further thiolated by nucleophilic aromatic substitution (SNAr) reaction to give emissive materials in the solid state following aggregation-induced emission (AIE) fashion.

Cited by 10 publications

References 25 publications

Toward Taming the Chemical Reversibility of Perfluoropyridine through Molecular Design with Applications to Pre- and Postmodifiable Polymer Architectures

Toward Taming the Chemical Reversibility of Perfluoropyridine through Molecular Design with Applications to Pre- and Postmodifiable Polymer Architectures

Revisiting the Role of Charge Transfer in the Emission Properties of Carborane–Fluorophore Systems: A TDDFT Investigation

Rational design for thermochromic luminescence in amorphous polystyrene films with bis‐o‐carborane‐substituted enhanced conjugated molecule having aggregation‐induced luminochromism

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