Photophysical and thermophysical behavior of D-π-A-type fluorinated diphenylacetylenes bearing an alkoxy and an ethoxycarbonyl group at both longitudinal molecular terminals

Yamada, Shigeyuki; Kataoka, Mitsuki; Yoshida, Kôji; Nagata, Masakazu; Agou, Tomohiro; Fukumoto, Hiroki; Konno, Tsutomu

doi:10.1016/j.jfluchem.2022.110032

Cited by 3 publications

(13 citation statements)

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“…Syntheses of CN-terminated 1 and CO 2 Et-terminated 2 were performed using the common synthetic intermediate 4 , which was prepared by a Pd(0)-catalyzed Sonogashira cross-coupling reaction according to our previous report [ 16 , 20 ]. The CN-terminated molecules 1a and 1b were synthesized in 26% and 66% yield, respectively, via an addition–elimination reaction between pentafluorobenzonitrile and 4-semifluoroalkoxy-substituted phenylethynyllithium, which was readily prepared from 4 .…”

Section: Resultsmentioning

confidence: 99%

“… Chemical structures of ( a ) PLLC molecules I – III obtained from the literature [ 11 , 12 , 13 ] and ( b ) fluorinated bistolane-type PLLCs IV–VI [ 14 , 15 ] and ( c ) fluorinated tolane-type PLLCs VII and VIII developed by our group [ 16 , 17 ]. …”

Section: Figures Scheme and Tablesmentioning

confidence: 99%

“…Our research group has successfully developed a family of donor-π-acceptor (D-π-A)-type fluorinated bistolane derivatives IV to VI ; however, their synthetic procedures were tedious and inefficient ( Figure 1 b) [ 14 , 15 ]. Furthermore, our group has also developed PLLC molecules VII and VIII ( Figure 1 c) using fluorinated tolanes as mesogens, which are easy to synthesize [ 16 , 17 ]. These molecules exhibit a nematic (N) phase with the LC phase as the only orientational order, and their Cry–N phase transition significantly reduces the fluorescence quantum yields (Φ PL ).…”

Section: Introductionmentioning

confidence: 99%

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Donor-π-Acceptor-Type Fluorinated Tolane Containing a Semifluoroalkoxy Chain as a Condensed-Phase Luminophore

et al. 2023

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Photoluminescent liquid-crystalline (PLLC) molecules, which can easily tune the PL behavior through the crystal (Cry)–LC phase transition, have attracted significant attention. Previously, we have demonstrated that the incorporation of a semifluoroalkoxy chain into π-conjugated mesogen is a promising approach for developing PLLC molecules with PL and SmA LC characteristics. We focused on the LC and PL characteristics of the molecules induced by the semifluoroalkoxy chain and fluorinated tolanes in the condensed phase. In this study, we developed cyano- or ethoxycarbonyl-terminated donor-π-acceptor-type fluorinated tolanes containing a semifluoroalkoxy flexible chain. The cyano-terminated fluorinated tolanes exhibited intense light-blue photoluminescence in the crystalline phase and did not exhibit any LC phase. In contrast, blue photoluminescence in the ethoxycarbonyl-terminated analogs was slightly weak; however, they exhibited Cry–SmA phase transition during the heating and cooling processes. The PL intensity of the ethoxycarbonyl-terminated fluorinated tolanes significantly decreased in the SmA phase; however, their PL colors changed during the Cry–SmA phase transition. This indicates that the developed tolanes are promising temperature-dependent PL materials, such as PL thermosensors or PL thermometers.

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Section: Resultsmentioning

confidence: 99%

Section: Figures Scheme and Tablesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Donor-π-Acceptor-Type Fluorinated Tolane Containing a Semifluoroalkoxy Chain as a Condensed-Phase Luminophore

et al. 2023

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“…[15] In contrast, 10-F with a COOEt group or 11-F with a COOH group was observed to show light-blue PL with a PL band at a λ PL of approximately 427 nm for 10-F and 435 nm for 11-F in dilute CH 2 Cl 2 solution. [22] 9-F with a CF 3 group had a very low Φ PL of 0.04 due to rapid internal conversion in dilute solution, whereas a slightly high Φ PL was observed in 10-F with a COOEt (0.19) and 11-F with a COOH (0.33). This is because 10-F and 11-F can form extreme structures between triple bonds and cumulative double bonds due to resonance effects in contrast to 9-F (Figure 11).…”

Section: Electronic Effect Of Longitudinal Terminal Substituent On Th...mentioning

confidence: 98%

“…To further clarify the electronic effect of terminal substituents introduced along the major molecular axis on the PL behavior, we investigated the PL behavior of fluorinated tolanes with an electron-withdrawing group (EWG) on the fluorinated aromatic rings or an electron-donating group (EDG) on the nonfluorinated aromatic rings (Figure 5). [15,22,23] The molecule 9-F with a CF 3 group at the longitudinal terminal position on the fluorinated aromatic ring exhibited ultraviolet (UV) emission with a PL band at a λ PL near 359 nm in hexane solution (Figure 10a; top). [15] In contrast, 10-F with a COOEt group or 11-F with a COOH group was observed to show light-blue PL with a PL band at a λ PL of approximately 427 nm for 10-F and 435 nm for 11-F in dilute CH 2 Cl 2 solution.…”

Section: Electronic Effect Of Longitudinal Terminal Substituent On Th...mentioning

confidence: 99%

Development of Donor‐π‐Acceptor‐Type Fluorinated Tolanes as Compact Condensed Phase Luminophores and Applications in Photoluminescent Liquid‐Crystalline Molecules

Yamada

Konno

2023

The Chemical Record

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Fluorinated tolanes, produced by introducing fluorine atoms into one of the aromatic rings of tolane, emitted almost no fluorescence in a solution state, but the fluorescence intensity increased dramatically in the crystalline state because of intermolecular H⋅⋅⋅F hydrogen bonds. The photoluminescent (PL) colors depend on the molecular orbitals, dipole moments, and molecular aggregated structures can be varied by controlling terminal substituents along the major molecular axis. The introduction of a long alkoxy or semifluoroalkoxy unit as a flexible chain into the terminal positions along the major molecular axis induced the formation of a liquid‐crystalline (LC) phase; fluorinated tolanes act both as luminophores and as mesogens, leading to the molecular design of new photoluminescent LC molecules (PLLCs). The results also indicated that a fluorinated tolane dimer, which consists of two fluorinated tolanes linked by a flexible alkylene spacer, also becomes a novel PLLC.

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Development of Hydrogen-Bonded Dimer-Type Photoluminescent Liquid Crystals of Fluorinated Tolanecarboxylic Acid

et al. 2022

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Functional molecules possessing photoluminescence (PL) and liquid-crystalline (LC) behaviors, known as photoluminescent liquid crystals, along with a small molecular structure, have attracted significant attention. Fluorinated tolane skeletons are small π-conjugated structures, which are promising candidates for such functional molecules. These structures were revealed to exhibit strong PL in solid state but no LC behavior. Based on a report on hydrogen-bonded dimer-type LC molecules of carboxylic acid, in this study, we designed and synthesized a series of fluorinated tolanecarboxylic acids (2,3,5,6-tetrafluoro-4-[2-(4-alkoxyphenyl)ethyn-1-yl]benzoic acids) as promising PLLC molecules. Evaluation of the LC behavior revealed that fluorinated tolanecarboxylic acids with a longer alkoxy chain than a butoxy chain exhibited nematic LC behavior. Additionally, fluorinated tolanecarboxylic acids showed intense PL in the solution and crystalline states. Notably, fluorinated tolanecarboxylic acid with an aggregated structure in the nematic LC phase also exhibited PL with a slight blue shift in PL maximum wavelength compared to the crystalline state. The present fluorinated tolanecarboxylic acid exhibiting PL and LC characteristics in a single molecule can be applied to thermoresponsive PL materials, such as a PL thermosensor.

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Photophysical and thermophysical behavior of D-π-A-type fluorinated diphenylacetylenes bearing an alkoxy and an ethoxycarbonyl group at both longitudinal molecular terminals

Cited by 3 publications

References 33 publications

Donor-π-Acceptor-Type Fluorinated Tolane Containing a Semifluoroalkoxy Chain as a Condensed-Phase Luminophore

Donor-π-Acceptor-Type Fluorinated Tolane Containing a Semifluoroalkoxy Chain as a Condensed-Phase Luminophore

Development of Donor‐π‐Acceptor‐Type Fluorinated Tolanes as Compact Condensed Phase Luminophores and Applications in Photoluminescent Liquid‐Crystalline Molecules

Development of Hydrogen-Bonded Dimer-Type Photoluminescent Liquid Crystals of Fluorinated Tolanecarboxylic Acid

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