Blue two-photon excited fluorescence of several D-$pi;-D, A-$pi;-A, and D-$pi;-A compounds featuring dimesitylboryl acceptor*1

Cao, Du Xia

doi:10.1016/s0022-328x(04)00262-1

Cited by 5 publications

(7 citation statements)

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“…The well‐structured nature of these bands contrasts the typically broad and featureless absorptions of polyfluorenes;12 they are attributed to π–π* transitions with a strong component of π–n B * charge transfer. The latter is consistent with DFT calculations reported by Fang and co‐workers on 2,7‐bis(dimesitylboryl)‐9,9‐diethylfluorene 17. Both polymers are highly emissive in the blue‐violet region (PF‐BM Φ =84 %, PF‐BT Φ =81 % in CH 2 Cl 2 ; Figure 1), and the bands almost perfectly mirror the absorptions with very small Stokes shifts, indicative of a highly rigid structure 12…”

Section: Methodssupporting

confidence: 89%

“…The absorption spectra of PF‐BM and PF‐BT in CH 2 Cl 2 show bands with vibronic fine structure and maxima at approximately 390 nm that are red‐shifted by approximately 20 nm in comparison with the related molecular species 2,7‐bis(dimesitylboryl)‐9,9‐diethylfluorene17 (371 nm) and by more than 80 nm relative to parent dihexylfluorene. The well‐structured nature of these bands contrasts the typically broad and featureless absorptions of polyfluorenes;12 they are attributed to π–π* transitions with a strong component of π–n B * charge transfer.…”

Section: Methodsmentioning

confidence: 96%

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Universal Scaffold for Fluorescent Conjugated Organoborane Polymers

Jäkle

2009

Angewandte Chemie

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Conjugated organoboron polymers represent an attractive class of new materials with diverse potential applications, including as nonlinear optical materials, conduction and emission layers for organic light-emitting devices, and chemosensors for anions and toxic small molecules. [1] Typical methods for their synthesis are based on hydroboration polymerization techniques [2] and polycondensation reactions, [3,4] including the metal-catalyzed C À C bond formation of suitable preformed organoboron building blocks. [5, 6] An alternative highly modular approach is to prepare a universal reactive polymer scaffold that can easily be transformed into a range of other polymers with widely varying properties and applications through straightforward polymer modification procedures. [4,7,8] For instance, in the case of polyolefins the reactive poly(4-dibromoboryl styrene) is readily converted to 1) a range of polymeric Lewis acids with variable degree of Lewis acidity, 2) luminescent sensor materials with pendant anion binding sites, 3) solutionprocessable polymeric organoboron analogues of the wellknown OLED device material tris(8-hydroxyquinolinato)aluminum (Alq 3 ). Even new ligand frameworks for redoxactive metallopolymers become available. [9,10] A universal fluorescent conjugated organoboron polymer scaffold would be very desirable owing to the interesting effects relating to the extended p p -p* conjugation [1] via the empty boron p orbital throughout the polymer main chain. Moreover, use of a single precursor polymer has the great advantage that the electronic and photophysical characteristics can more reliably be compared for polymer chains of equal length and distribution. We report herein the successful synthesis of such a novel polymer framework based on polyfluorene and demonstrate its utility as a universal scaffold for luminescent fluorene polymers that feature tricoordinate aryl borane and tetracoordinate organoboron quinolate functionalities.The main challenge in the preparation of a reactive polymer [ArB(X)] n (Ar = arylene bridge, X = labile substituent) is the need to achieve excellent control over the condensation reaction such that the (disubstituted) linear polymer forms selectively, without conversion of the remaining labile halide substituent X on boron. We chose the poly(fluorenylborane) framework [FlB(Br)] n (Fl = 9,9-dialkyl fluorenyl) because of the high selectivity with which this reactive polymer scaffold can be prepared from simple precursor components and the high luminescence quantum efficiency typically associated with fluorene polymers. [11,12] In a first attempt, we treated the bifunctional organotin species Fl(SnMe 3 ) 2 with an equimolar amount of BBr 3 . However, owing to the extremely high reactivity of BBr 3 , the polymerization was difficult to control. Instead, we then decided to treat the preformed (and less reactive) aryl dibromoborane species Fl(BBr 2 ) 2 with the aryl ditin reagent Fl(SnMe 3 ) 2 in an organometallic polycondensation reaction (Scheme 1). [13] The polymerizatio...

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Section: Methodssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 96%

Universal Scaffold for Fluorescent Conjugated Organoborane Polymers

Jäkle

2009

Angewandte Chemie

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“…[1][2][3] The vacant p z -orbital on boron allows significant interactions with organic p-systems as p-acceptors. Such compounds exhibit strong fluorescence emission, 4,5 second and third order non-linear properties, 6,7 and can be used as emitting and/or electron transporting materials in organic light emitting diodes (OLEDs). [8][9][10][11] Due to their Lewis acidity, these materials show considerable anion sensing abilities, especially for fluoride.…”

Section: Introductionmentioning

confidence: 99%

“…[12][13][14][15][16] To stabilize the Lewis acid boron center, bulky aryl substituents, such as dimesitylboryl moieties (B(Mes) 2 , Mes = 2,4,6-Me 3 C 6 H 2 ), are widely used to enhance steric hindrance. 5,12,[17][18][19] The benzodiazaboroles investigated here follow, as shown in Fig. 1, a different approach: two neighbouring nitrogen atoms supply sufficient electron density in their p-orbitals to stabilize the whole boron-containing aromatic ring.…”

Section: Introductionmentioning

confidence: 99%

Solvatochromism and fluoride sensing of thienyl-containing benzodiazaboroles

Schwedler

Eickhoff

Brockhinke

et al. 2011

Phys. Chem. Chem. Phys.

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Static and time-resolved fluorescence studies were carried out to investigate the photophysical properties and fluoride sensing abilities of highly fluorescent thienyl-containing 1,3-diethyl-1,3,2-benzodiazaboroles. Absorption and fluorescence spectra were measured in various solvents, showing the fluorophores to emit in the visible wavelength region with colors varying from blue to orange and quantum yields ranging between 0.21 and 1. Measured Stokes shifts of 2898 cm(-1) to 9308 cm(-1) were used to calculate the difference between excited- and ground-state dipole moments of the fluorophores. Values up to 18.8 D are of the same magnitude as for designed polarity probes such as PRODAN, supporting the idea of internal charge transfer transitions. Quenching studies with pyridine observing static and time-resolved fluorescence revealed a purely dynamic quenching mechanism and low Lewis acidity of the boron within the benzodiazaborolyl moiety compared to other triarylboranes. In contrast to this, quenching with fluoride was shown to stem from adduct formation. Reversible complexation of fluoride follows a simple mechanism for multi-functionalized benzodiazaboroles 2b and 2c, while those containing only one benzodiazaborole moiety (1 and 2a) show a more complicated behaviour, which might be explained by aggregation. Combining a benzodiazaborole group and a dimesitylborane function results in spectrally switchable fluoride sensors 3a and 3b, since the two boron sides can be deactivated for fluorescence in a stepwise manner.

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“…Tricoordinate boron-containing π - conjugated materials have attracted increasing attention due to their intriguing electronic and photophysical properties, which arise from their unique ability to accept electrons through the p π –π* conjugation between the vacant p orbital on the boron atom and the π* orbital of the π - conjugated framework . When an appropriate electron donor is present, the electron-accepting ability of the boron center makes organoboron compounds display intense intramolecular charge transfer (CT) transitions, which have been exploited extensively in a wide range of applications, such as nonlinear optical materials, , two-photon absorption and emission materials, , organic light-emitting diodes, − and chemical sensors for fluoride and cyanide anions. − …”

mentioning

confidence: 99%

Through-Space Charge-Transfer Emitting Biphenyls Containing a Boryl and an Amino Group at the o,o′-Positions

Pan

Zhao

et al. 2011

Org. Lett.

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A new class of organoboron compounds containing a boryl and an amino group at the o,o'-positions of biphenyls display bright through-space intramolecular charge transfer fluorescence owing to the close contact between the boryl and the amino groups. Binding of the fluoride ions results in the remarkable blue shift and color change of the fluorescence, enabling colorimetric and ratiometric fluoride ion sensing.

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Blue two-photon excited fluorescence of several D-$pi;-D, A-$pi;-A, and D-$pi;-A compounds featuring dimesitylboryl acceptor*1

Cited by 5 publications

References 0 publications

Universal Scaffold for Fluorescent Conjugated Organoborane Polymers

Universal Scaffold for Fluorescent Conjugated Organoborane Polymers

Solvatochromism and fluoride sensing of thienyl-containing benzodiazaboroles

Through-Space Charge-Transfer Emitting Biphenyls Containing a Boryl and an Amino Group at the o,o′-Positions

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