From Controllable Attached Isolation Moieties to Possibly Highly Efficient Nonlinear Optical Main-Chain Polyurethanes Containing Indole-Based Chromophores

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation-cyclization-iodination-alkylation sequence

A library of 19 differently substituted 3-iodoindoles is generated by a consecutive four-component reaction starting from ortho-haloanilines, terminal alkynes, N-iodosuccinimide, and alkyl halides in yields of 11-69%. Initiated by a copper-free alkynylation, followed by a base-catalyzed cyclizive indole formation, electrophilic iodination, and finally electrophilic trapping of the intermediary indole anion with alkyl halides provides a concise one-pot synthesis of 3-iodoindoles. The latter are valuable substrates for Suzuki arylations, which are exemplified with the syntheses of four derivatives, some of them are blue emitters in solution and in the solid state, in good yield.

A series of dendronized hyperbranched polymers with dendritic chromophore moieties in the periphery: convenient synthesis and large nonlinear optical effects

Excellent optical transparency and NLO coefficients were achieved by introducing dendritic chromophore moieties to the periphery of dendronized hyperbranched polymers.

Dendronized hyperbranched polymers containing isolation chromophores: design, synthesis and further enhancement of the comprehensive NLO performance

New dendronized hyperbranched polymers (DHPs) constructed by dendronized monomers, exhibit good comprehensive NLO performance, especially for thermostability.

Main chain dendronized hyperbranched polymers: convenient synthesis and good second-order nonlinear optical performance

By using low generation dendrimers as macromonomers, two main chain dendronized hyperbranched polymers, with good comprehensive nonlinear optical performance, were prepared conveniently with satisfying yields through a one-pot “A₃ + B₂” approach.

The integration of an “X” type dendron into polymers to further improve the comprehensive NLO performance

Three polymers were designed and synthesized, by utilizing an “X” type dendrimer containing five nitro-based azo chromophore moieties, which exhibit good processability and good nonlinear optical performance, especially for NLO thermostability.

Dendrimers with large nonlinear optical performance by introducing isolation chromophore, utilizing the Ar/ArF self-assembly effect, and modifying the topological structure

By the combination of divergent and convergent approach, a new series of NLO dendrimers (G1-PFPh-NS-GL to G3-PFPh-NS-GL) was conveniently prepared with satisfied yields through the powerful "click chemistry" reaction, in which perfluoroaromatic rings were introduced in the periphery, two types of chromophores were arranged with regular AB structure, and their topological structure was improved to a more spherical shape. All the dendrimers demonstrated good processability, and G1-PFPh-NS-GL exhibited the highest NLO effect of 221 pm/V among the three dendrimers.

From nitro- to sulfonyl-based chromophores: improvement of the comprehensive performance of nonlinear optical dendrimers

Through the combination of the divergent and convergent approaches, coupled with the utilization of the powerful Sharpless "click-chemistry" reaction, two series of sulfonyl-based high-generation NLO dendrimers were conveniently prepared with high purity and in satisfactory yields. Thanks to the perfect three-dimensional (3D) spatial isolation from the highly branched structure and the isolation effect of the exterior benzene moieties and the interior triazole rings, these dendrimers exhibited large second harmonic generation coefficient (d33) values up to 181 pm V(-1), which, to the best of our knowledge, is the highest value so far for polymers containing sulfonyl-based chromophore moieties. Meanwhile, compared with the nitro-chromophore-based analogues, their optical transparency and NLO stability were improved in a large degree, due to the lower dipole moment (μ) and the special main-chain structure of sulfonyl-based chromophore in these dendrimers.

Spectroscopic and quantum mechanical study of three novel azo-materials containing indole and sulfonyl based chromophores

In this essay, three novel nonlinear optical (NLO) azo-materials containing indole and sulfonyl based chromophores were studied in-depth by using Fourier transform (FT) IR, FT-Raman spectra and density functional theory (DFT). The scaled theoretical results were shown to be in good agreement with the experimental data. In addition, the computed (1)H nuclear magnetic resonance (NMR) and UV-vis absorption wavelengths were also discussed compared with experimental data. The large β values calculated by the DFT methods showed that the studied molecules were good NLO materials, and the molecule which owned a larger substituent group on the indole chromophore moieties had a larger value. Furthermore, simultaneous infrared and Raman activity suggested that intramolecular charges might transfer through the conjugated framework from the electronic donor group to electronic acceptor group. The HOMO-LUMO gap analysis and molecular electrostatic potential (MEP) maps also supported this viewpoint.

New hyperbranched polytriazoles containing isolation chromophore moieties derived from AB4 monomers through click chemistry under copper(I) catalysis: improved optical transparency and enhanced NLO effects

By modifying a synthetic procedure, two new hyperbranched polytriazoles (HP1 and HP2) containing isolation chromophores were synthesized successfully through click chemistry reactions under copper(I) catalysis. For the first time, these two polymers were derived from an AB(4)-type monomer, although they contain different end-capping chromophores. They are soluble in normal polar organic solvents and are well characterized. Thanks to the presence of the isolation chromophore, the two polymers demonstrate good nonlinear optical (NLO) properties and optical transparency, making them promising candidates for practical applications.