Optical Properties of Benzotriazole-Based Conjugated Polyelectrolytes

Colorful Luminescence of Conjugated Polyelectrolytes Induced by Molecular Weight

Due to their distinctive intrinsic advantages, the nanoaggregates of conjugated polyelectrolytes (CPEs) are fascinating and attractive for various luminescence applications. Generally, the emission luminescence of CPEs is determined by the conjugated backbone structure, i.e., different conjugated backbones of CPEs produce emission luminescence with different emission wavelength bands. Here, we polymerized the bis(boronic ester) of benzothiadiazole and an alkyl sulfonate sodium-substituted dibromobenzothiatriazole to provide PBTBTz-SO₃Na with different molecular weights via controlling the ratio of the monomer and the catalyst. Theoretically, the CPEs with the same molecular structure usually display similar photoelectronic performances. However, the resulting PBTBTz-SO₃Na reveal a similar light absorption property, but different luminescence. The higher molecular weight is, the stronger the fluorescence intensity of PBTBTz-SO₃Na that occurs. PBTBTz-SO₃Na with different molecular weights have different colors of luminescence. It is well known that the molecular aggregates often led to weaker luminescent properties for most of the conjugated polymers. However, PBTBTz-SO₃Na exhibits a higher molecular weight with an increasing molecular chain aggregation, i.e., the nanoaggregates of PBTBTz-SO₃Na are beneficial to emission luminescence. This work provides a new possible chemical design of CPEs with a controllable, variable luminescence for further optoelectronics and biomedicine applications.

In-Situ Synthesis of TiO2@GO Nanosheets for Polymers Degradation in a Natural Environment

Plastic photodegradation naturally takes 300-500 years, and their chemical degradation typically needs additional energy or causes secondary pollution. The main components of global plastic are polymers. Hence, new technologies are urgently required for the effective decomposition of the polymers in natural environments, which lays the foundation for this study on future plastic degradation. This study synthesizes the in-situ growth of TiO₂ at graphene oxide (GO) matrix to form the TiO₂@GO photocatalyst, and studies its application in conjugated polymers' photodegradation. The photodegradation process could be probed by UV-vis absorption originating from the conjugated backbone of polymers. We have found that the complete decomposition of various polymers in a natural environment by employing the photocatalyst TiO₂@GO within 12 days. It is obvious that the TiO₂@GO shows a higher photocatalyst activity than the TiO₂, due to the higher crystallinity morphology and smaller size of TiO₂, and the faster transmission of photogenerated electrons from TiO₂ to GO. The stronger fluorescence (FL) intensity of TiO₂@GO compared to TiO₂ at the terephthalic acid aqueous solution indicates that more hydroxyl radicals (•OH) are produced for TiO₂@GO. This further confirms that the GO could effectively decrease the generation of recombination centers, enhance the separation efficiency of photoinduced electrons and holes, and increase the photocatalytic activity of TiO₂@GO. This work establishes the underlying basic mechanism of polymers photodegradation, which might open new avenues for simultaneously addressing the white pollution crisis in a natural environment.

Benzyne–azide polycycloaddition: a facile route toward functional polybenzotriazoles

An efficient benzyne–azide polycycloaddition is established and functional poly(benzotriazole)s are produced under mild reaction conditions.

Facile alkylation of 4-nitrobenzotriazole and its platelet aggregation inhibitory activity

We explored the facile alkylation of 4-nitrobenzotriazole under basic conditions and the synthesized derivatives were tested for their potential ADP induced platelet aggregation inhibition activity in comparison with standard drug ticagrelor (selective P2Y12 inhibitor). The nitro group at 4-position is highly activating toward alkylation reactions (under strong basic conditions) and resulted in formation of degradation product like 3-nitrobenzene-1,2-diamine which make isolation of alkyl products very difficult. We optimized the reaction under mild basic condition (potassium carbonate and DMF) which is devoid of any degradation product. This is perhaps the first report of 4-nitrobenzotriazole derivatives possessing platelet aggregation inhibitory activity. Generally activity increases with increase in length of alkyl chain and 1-alkyl positional isomers were found to be more potent than 2-alkyl isomers. The benzoyl derivative was found to be the most potent [compound 22; (4-Nitro-1H-benzotriazol-1-yl)(phenyl)methanone; IC₅₀=0.65±0.10mM] which may be attributed to electronegative oxygen atom and aromatic ring. Benzyl derivatives [compound 20; 1-Benzyl-4-nitro-1H-benzotriazole; IC₅₀=0.81±0.08mM, compound 21; 2-Benzyl-4-nitro-2H-benzotriazole; IC₅₀=0.82±0.19mM] and sulfonyl derivative [compound 23; 1-[(4-Methylphenyl)sulfonyl]-4-nitro-1H-benzotriazole; IC₅₀=0.82±0.19mM] are also found to be highly active. Furthermore, all compounds possess P2Y12 binding affinity as confirmed by VASP/P2Y12 phosphorylation assay.