New Fluorophores with Rod-Shaped Polycyano π-Conjugated Structures:  Synthesis and Photophysical Properties

Yamaguchi, Yoshihiro; Ochi, Takanori; Wakamiya, Tateaki; Matsubara, Yoichi; Yoshida, Zen‐ichi

doi:10.1021/ol0528991

Cited by 59 publications

(36 citation statements)

References 8 publications

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“…Consequently, a linear relationship is again obtained between the F F and s p + values in the solid state, as shown in Figure 8, which affords Equation (8). Although a similar linear relationship between the F F and s p values has been reported for other oligo(phenyleneethynylene) derivatives in solution, [24] such a relationship in a solid-state emission is unprecedented to the best of our knowledge. In a comparison of Equations (3) and (8), the higher intercept value with the smaller slope constant in Equation (8) demonstrates a trend that the value for F F in the solid state becomes higher than those in solution.…”

Section: Dnsupporting

confidence: 71%

Highly Emissive Diborylphenylene‐Containing Bis(phenylethynyl)benzenes: Structure–Photophysical Property Correlations and Fluoride Ion Sensing

Zhao¹,

Sakuda²,

Wakamiya³

et al. 2009

Chemistry A European J

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A series of 2,5-bis(dimesitylboryl)-1,4-bis(arylethynyl)benzenes 1-6 that contain various p-substituents on the terminal benzene rings, including NPh(2) (1), OMe (2), Me (3), H (4), CF(3) (5), and CN (6) groups, were synthesized, and the effects of the p-substituents on the absorption and fluorescence properties were investigated both in solution and in the solid state. Linear relationships were obtained not only between the Hammett sigma(p)(+) constants of the p-substituents and the absorption and fluorescence maxima, quantum yields, and excited-state dynamics parameters in solution, but also between the sigma(p)(+) constants and the fluorescence quantum yields in the solid state. An important finding extracted from these results is that the suppressed fluorescence quenching in the solid state is a common feature for the present laterally boryl-substituted pi-conjugated skeletons. Hence, the diborylphenylene can serve as a useful core unit to develop highly emissive organic solids. In fact, most of the derivatives showed more intense emission in the solid state than in solution. In addition to these studies, the titration experiment of 1 by the addition of nBu(4)NF was conducted, which showed the stepwise bindings of two fluoride ions with high association constants as well as a drastic change in the fluorescence spectra, while constantly maintaining high quantum yields (0.61-0.76), irrespective of the binding modes. This result also demonstrated the potential utility of the present molecules as an efficient fluorescent fluoride ion sensor.

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Section: Dnsupporting

confidence: 71%

Highly Emissive Diborylphenylene‐Containing Bis(phenylethynyl)benzenes: Structure–Photophysical Property Correlations and Fluoride Ion Sensing

Zhao¹,

Sakuda²,

Wakamiya³

et al. 2009

Chemistry A European J

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“…74−85 Furthermore, it has been found that donor/acceptor modification shown in structure A is superior to that shown in structure B for emission in the visible region ( Figure 4). 86,87 On the basis of these results (the effectiveness of donor/ acceptor tuning, Figure 3) and the superiority of tuning mode A (see Figure 4), 20 compounds (D/A-BPBs: Type I, Type II, Type III, Type IV, and Type V) were designed as shown in Figure 5.…”

Section: ■ Introductionmentioning

confidence: 99%

Highly Emissive Whole Rainbow Fluorophores Consisting of 1,4-Bis(2-phenylethynyl)benzene Core Skeleton: Design, Synthesis, and Light-Emitting Characteristics

et al. 2015

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To create the whole-rainbow-fluorophores (WRF) having the small Δλem (the difference of λem between a given fluorophore and nearest neighboring fluorophore having the same core skeleton) values (<20 nm) in full visible region (λem: 400-650 nm), the high log ε (>4.5), and the high Φf (>0.6), we investigated molecular design, synthesis, and light-emitting characteristics of the π-conjugated molecules (D/A-BPBs) consisting of 1,4-bis(phenylethynyl)benzene (BPB) modified by donor groups (OMe, SMe, NMe2, and NPh2) and an acceptor group (CN). As a result, synthesized 20 D/A-BPBs (1a-5d) were found to be the desired WRF. To get the intense red fluorophore (Φf> 0.7, λem > 610 nm), we synthesized new compounds (5e-5i) and elucidated their photophysical properties in CHCl3 solution. As a result, 5h, in which a 4-cyanophenyl group is introduced to the para-position of two benzene rings in the terminal NPh2 group of 5d, was found to be the desired intense red fluorophore (log ε = 4.56, Φf = 0.76, λem = 611 nm). The intramolecular charge-transfer nature of the S1 state of WRF (1a-5d) was elucidated by the positive linear relationship between optical transition energy (νem) from the S1 state to the S0 state and HOMO(D)-LUMO(A) difference, and the molecular orbitals calculated with the DFT method. It is demonstrated that our concept (Φf = 1/(exp(-Aπ) + 1)) connected with the relationship between Φf and magnitude (Aπ) of π conjugation length in the S1 state can be applied to WRF (1a-5d). It is suggested that the prediction of Φf from a structural model can be achieved by the equation Φf = 1/(exp(-((ν̃a - ν̃f)(1/2) × a(3/2)) + 1), where ν̃a and ν̃f are the wavenumber (cm(-1)) of absorption and fluorescence peaks, respectively, and a is the calculated molecular radius. From the viewpoint of application of WRF to various functional materials, the light-emitting characteristics of 1a-5i in doped polymer films were examined. It was demonstrated that 1a-5i dispersed in two kinds of polymer film (PST and PMMA) emit light at the whole visible region and have the small Δλem values (<20 nm) and the high Φf values (>0.6). Therefore, the present D/A-BPBs can be said to be the desired WRF even in the doped polymer film.

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“…In fact, several oligomers of ethynylene-extended arenes and heteroarenes have been designed and synthesised. [16][17][18][19][20][21] It has been shown that they function as nanoscale "molecular wires", with the extent of intramolecular conjugation dependent on the topology of the p system and the molecular length. [22][23][24] It is well known that both fluorene and anthracene are blue fluorophores whose derivatives have been widely used as emitting materials; in fact, some poly(fluorene-co-anthracene)s with controlled alternative fluorene and anthracene structures have been reported.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Photophysical Behaviour of Ethynyl Fluorenes and Ethynyl Anthracenes Investigated by Fast and Ultrafast Time‐Resolved Spectroscopy

et al. 2012

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Detailed investigations by time-resolved transient absorption and fluorescence spectroscopies with nano- and femtosecond time resolutions are carried out with the aim of characterising the lowest excited singlet and triplet states of three ethynyl fluorenes (1-3) and three ethynyl anthracenes (4-6) in solvents of different polarity. The solvent is found to modify the deactivation pathways of the lowest excited singlet state of compounds 1-4, thus changing their fluorescence, intersystem crossing and internal conversion efficiencies. The fluorescence and triplet yields gradually decrease, while the internal conversion quantum yield increases upon increasing the solvent dielectric constant. These experimental results, coupled with the marked fluorosolvatochromic effect, point to the involvement of an emitting state with a charge-transfer (CT) character, strongly stabilised by polar solvents. This is proved by ultrafast spectroscopic studies in which two transients, distinguished by characteristic spectral shapes assigned to locally excited (LE) and CT states, are detected, the CT state being the longer lived and fluorescent one in highly polar solvents. The intramolecular LE→CT process, operative in highly polar media, becomes particularly fast (up to ≈300 fs) in the case of the NO(2) derivative 1. No push-pull character is found for 5 and 6, which exhibit different photophysical behaviour; indeed, the solvent polarity does not modify significantly the dynamics of the lowest excited singlet states. Quantum mechanical calculations at the TDDFT level are also used to determine the state order and nature of the lowest excited singlet and triplet states and to rationalise the different photophysical behaviour of fluorine and anthracene derivatives, particularly concerning the intersystem crossing process.

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New Fluorophores with Rod-Shaped Polycyano π-Conjugated Structures: Synthesis and Photophysical Properties

Cited by 59 publications

References 8 publications

Highly Emissive Diborylphenylene‐Containing Bis(phenylethynyl)benzenes: Structure–Photophysical Property Correlations and Fluoride Ion Sensing

Highly Emissive Diborylphenylene‐Containing Bis(phenylethynyl)benzenes: Structure–Photophysical Property Correlations and Fluoride Ion Sensing

Highly Emissive Whole Rainbow Fluorophores Consisting of 1,4-Bis(2-phenylethynyl)benzene Core Skeleton: Design, Synthesis, and Light-Emitting Characteristics

Comprehensive Photophysical Behaviour of Ethynyl Fluorenes and Ethynyl Anthracenes Investigated by Fast and Ultrafast Time‐Resolved Spectroscopy

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