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Donor-acceptor chromophores were almost quantitatively introduced into the side chains of a polystyrene derivative by sequential "click chemistry"-type addition reactions as an efficient postfunctionalization method. The first click reaction is the conventional Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC), and the second one is the atom-economic addition of strong acceptor molecules, such as tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ), to the aniline-substituted electron-rich alkynes. Steric hindrance was found to be an important factor in determining the reactivity of alkyne-acceptor addition reactions. All obtained polymers showed good solubility in common organic solvents, and they were fully characterized by GPC, 1 H NMR and IR spectroscopy, and elemental analysis. After the acceptor addition, the polymers showed an intense charge-transfer (CT) band centered at ca. 480 nm for the TCNE adducts and ca. 710 nm for the TCNQ adducts. Electrochemical measurements of these polymers also revealed well-defined oxidation and reduction potentials, offering consistency between the electrochemical and optical band gaps. The second harmonic generation (SHG) coefficients (d 33 and d 15 ) of the polymer thin films were evaluated by SHG measurements before and after corona poling at 150 °C, a temperature that was determined on the basis of thermal analyses. The results show that the TCNE adducted polymers possess better SHG properties than the corresponding TCNQ adducted polymers, probably reflecting the superior chromophore mobility within the polymers.

Two series of well-defined brush polymers bearing a triazole moiety on each bristle were prepared from the click chemistry reactions of a poly(glycidyl azide) (PG) and a poly(4-azidomethylstyrene) (PS) with alkyne derivatives. The thin-film morphologies and properties, especially electrical memory performances, of these triazole-containing brush polymers were investigated in detail. The brush polymers with a triazole ring substituted with an alkyl or alkylenylphenyl group in the bristle exhibited only dielectric characteristics. By contrast, the other brush polymers bearing a triazole ring substituted with phenyl or its derivatives with a longer π-conjugation length in the bristle demonstrated excellent unipolar permanent memory behaviors with low power consumption, high ON/OFF current ratios and high stability and reliability under ambient air conditions. Furthermore, their memory type could be tuned to p-or n-type by the incorporation of an electron-donating or -accepting group into the phenyl unit linked to the triazole moiety. Overall, this study presents the first demonstration of the azide-alkyne click chemistry synthesis of triazole moieties with substituent(s) that exhibit a resonance effect; this approach is a very powerful synthetic route to develop electrical memory polymers suitable for the low-cost mass production of high-performance, polarity-free programmable memory devices.

The donor-acceptor chromophores constructed in the side chains of polystyrene derivatives by alkyne-acceptor click reactions clearly distinguished between hard and soft metal ions due to the diff erent color changes. The chromophores also showed the chemodocimetric sensing ability of some specifi c anions.Donor-acceptor chromophores were introduced into the side chains of a polystyrene derivative through the efficient click postfunctional addition reaction between dialkylaniline-activated alkynes and small acceptors, such as tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The resulting polystyrenes were fully characterized by GPC, 1 H NMR, IR spectroscopy, and elemental analysis. After the postfunctionalization, the polymers were highly colored due to the formed donor-acceptor chromophores in the side chains and these chromophores showed a colorimetric sensing behavior for some metal ions and anions. Some hard-to-borderline metal ions were always recognized by the dialkylanilino nitrogen atom, resulting in a decrease in the charge-transfer (CT) band intensity of the donor-acceptor chromophores. However, the recognition site of the soft Ag + ion was the cyano nitrogen atoms due to readily formed multivalent coordination, leading to a bathochromic shift in the CT bands for both TCNE-and TCNQ-adducted polymers. This remarkable dual colorimetric detection of two different types of metal ions was achieved by the elegant design of polymeric chemosensors. On the other hand, it was found that the dicyanoethene moieties of the side chain chromophores serve as a chemodosimeter for some anions. For example, the CN À ion underwent a nucleophilic addition reaction to the electron-deficient ethene moieties, resulting in a dramatic decrease in the CT bands. All types of sensing behavior of both cations and anions were visually recognized. The use of small molecular model compounds enabled the estimation of the kinetic parameters and the product structures. † Electronic supplementary information (ESI) available: Monomer synthesis, thermogravimetric analysis, electrochemistry, X-ray crystal structure, UV-vis-near IR spectra upon the addition of metal ions, 1 H NMR characterization of model compound with CN À monoadduct, and competitive experiments. See

Organic donor-acceptor dyes, formed by a high-yielding [2 + 2] cycloaddition-retroelectrocyclisation process between aniline-substituted alkynes and tetracyanoethylene (TCNE) or 7,7,8,8tetracyanoquinodimethane (TCNQ), were employed as novel photosensitizers without carboxylic acid anchoring groups in dye-sensitized solar cells (DSSCs). The efficient adsorption of the donor-acceptor dyes onto TiO 2 was confirmed by UV-vis and IR spectroscopies. The photovoltaic performances of the DSSCs suggested that the triphenylamine derivatives 3 and 4 provide higher current densities (J sc ) as compared to the corresponding dimethylaniline counter molecules 1 and 2. This was mainly due to the excellent charge-separation efficiencies and lower charge-recombination rates of the triphenylamine moieties. It was also found that the devices sensitized by the TCNQ-adducted dyes 2 and 4 display open-circuit voltages (V oc ) higher than those of the TCNE-adducted counter dyes 1 and 3. All these results were reasonably explained by the J-V curve fitting based on the equivalent-circuit model as well as the comparison between the absorption and incident-photon-to-current-conversion efficiency (IPCE) spectra.View Article Online a 0.25 cm 2 TiO 2 electrode composed of a transparent layer (15 mm) and scattering layer (10 mm) in CH 3 CN containing 2 M LiI and 0.025 M I 2 .This journal is