Abstract:Doping of π-conjugated
polymers or molecular compounds with
trivalent boron atoms has recently emerged as a viable strategy to
produce new materials with intriguing properties and functions. The
combination of boron with furan moieties has been only scarcely explored
so far, although the resulting furan-based materials have several
notable features, including favorable optoelectronic properties and
improved sustainability. Herein, we investigate the doping of α-polyfurans
with a varying number of boron atoms. … Show more
“…The higher molecular weight sample of PFB3T’‐B showed multiple series of peaks due to one or two additional thiophene units, which still primarily correspond to cyclic products. The formation of cyclic rather than linear conjugated polymers has been reported for Suzuki‐Miyaura polycondensation reactions with suitably shaped (kinked) monomers, [19] but has to our knowledge only rarely been observed [5l,14e,f] in Stille polymerization of thiophenes. In our case, cyclic tetramers and pentamers are obtained preferentially, possibly also aided by the bent shape of the dithienylborane building blocks (Figure 4b).…”
Main‐chain boron‐containing π‐conjugated polymers are attractive for organic electronic, sensing, and imaging applications. Alternating terthiophene‐borane polymers were prepared and the effects of regioisomeric attachment of the conjugated linker and variations in the electronic effect of the pendent aryl groups (2,4,6‐tri‐tert‐butylphenyl, Mes*; 2,4,6‐tris(trifluoromethyl)phenyl, FMes) examined. Pd2dba3/P(t‐Bu)3‐catalyzed Stille polymerization of arylbis(2‐thienyl)borane and arylbis(3‐thienylborane) with 2,5‐bis(trimethylstannyl)thiophene at 120 °C gave polymers with appreciable molecular weight but MALDI‐TOF MS analyses showed evidence of unusually prominent homocoupling. These defects could be suppressed by using brominated rather than iodinated monomers, more hindered 2,5‐bis(tri‐n‐butylstannyl)thiophene as comonomer, and Pd2dba3/P(o‐tol)3 as the catalyst at 100 °C. Under these conditions, macrocyclic species with n=3–10 repeating units formed preferentially according to MALDI‐TOF MS analyses. Photophysical studies revealed a prominent effect of the regiochemistry and the nature of the pendent aryl groups on the absorption and emission, giving rise to orange, yellow‐green, blue‐green, and blue emissive materials respectively. The electronic effects were rationalized through DFT calculations on bis(terthiophene) model systems.
“…The higher molecular weight sample of PFB3T’‐B showed multiple series of peaks due to one or two additional thiophene units, which still primarily correspond to cyclic products. The formation of cyclic rather than linear conjugated polymers has been reported for Suzuki‐Miyaura polycondensation reactions with suitably shaped (kinked) monomers, [19] but has to our knowledge only rarely been observed [5l,14e,f] in Stille polymerization of thiophenes. In our case, cyclic tetramers and pentamers are obtained preferentially, possibly also aided by the bent shape of the dithienylborane building blocks (Figure 4b).…”
Main‐chain boron‐containing π‐conjugated polymers are attractive for organic electronic, sensing, and imaging applications. Alternating terthiophene‐borane polymers were prepared and the effects of regioisomeric attachment of the conjugated linker and variations in the electronic effect of the pendent aryl groups (2,4,6‐tri‐tert‐butylphenyl, Mes*; 2,4,6‐tris(trifluoromethyl)phenyl, FMes) examined. Pd2dba3/P(t‐Bu)3‐catalyzed Stille polymerization of arylbis(2‐thienyl)borane and arylbis(3‐thienylborane) with 2,5‐bis(trimethylstannyl)thiophene at 120 °C gave polymers with appreciable molecular weight but MALDI‐TOF MS analyses showed evidence of unusually prominent homocoupling. These defects could be suppressed by using brominated rather than iodinated monomers, more hindered 2,5‐bis(tri‐n‐butylstannyl)thiophene as comonomer, and Pd2dba3/P(o‐tol)3 as the catalyst at 100 °C. Under these conditions, macrocyclic species with n=3–10 repeating units formed preferentially according to MALDI‐TOF MS analyses. Photophysical studies revealed a prominent effect of the regiochemistry and the nature of the pendent aryl groups on the absorption and emission, giving rise to orange, yellow‐green, blue‐green, and blue emissive materials respectively. The electronic effects were rationalized through DFT calculations on bis(terthiophene) model systems.
“…Over the past decades, boron-containing conjugated π-systems have frequently been employed to construct color-tunable π-conjugated polymers. [84][85][86][87] In a different approach, Wang, Li and co-workers demonstrated that multicolor emission that is dependent on the degree of polymerization can be achieved by chromophore assembly of nonconjugated side-chain functionalized polymers PB8 (Figure 3B). [88] They utilized a stimulus-responsive boron chromophore that exhibits different emission colors in its closed (red, tetracoordinate boron) and open conformation (blue, tricoordinate boron).…”
Section: Assembly Of Luminescent Boron Polymersmentioning
Boron-containing molecules and polymers are attractive as powerful tunable Lewis acids for small molecule activation and catalysis, as luminescent materials for organic electronic device and (bio)imaging applications, and as smart chemical sensors. While the characteristics of the boron-containing building blocks are attractive in and of themselves, their assembly into higher order supramolecular materials offers access to unique properties and emerging functions. Herein, we highlight recent achievements in the field of aggregated organoboron materials. We discuss how supramolecular interactions can be exploited to precisely control the structure of the assemblies and impact their functions as luminescent materials, recyclable and smart catalyst systems, chemical sensors, stimuli-responsive and self-healing materials.
“…The boron (B) atom is a special member of the main-group elements. Implanting B atom with an empty p-orbital endowed OCPs with intriguing optoelectronic properties that are distinct from other OCPs. ,− For example, OCPs with a tricoordinate B-center exhibited excellent toxic material (F/CN anions and amines) sensing properties. , Introducing tricoordinate or tetracoordinate B-building blocks with strong electron-withdrawing characteristics into polymeric backbones efficiently lowered the LUMOs of OCPs, consequently enhancing the electron-accepting and electron-transporting characteristics. ,− …”
Doping
the boron (B) element endowed organic π-conjugated
polymers (OCPs) with intriguing optoelectronic properties. Herein,
we introduce a new series of thienylborane-pyridine (BN) Lewis pairs via the facile reactions between thienylborane and
various pyridine derivatives. Particularly, we developed a “one-pot”
synthetic protocol to access BN2 with an unstable 4-bromopyridine
moiety. Polycondensations between the BN Lewis pairs
and distannylated thiophene afforded a new series of BN-cross-linked
polythiophenes (BN-PTs). Experiments revealed that BN-PTs exhibited highly uniform chemical structures, particularly
the uniform chemical environment of B-centers. BN-PTs
showed good stability in the solid state. PBN2 even maintained
the uniform B-center under high temperature or moisture conditions.
The studies further suggested that the presence of topological BN structures endowed the polymers with strong intramolecular
charge separation character. As a proof of concept, a representative BN-PT was tested as the catalyst for photocatalytic hydrogen
evolution.
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