Electrofluorochromism has attracted great attention due to the intelligence optoelectronic and sensing applications. The intrinsically switchable fluorophores with high solid-state fluorescence are regarded as key for ideal electrofluorochromic materials. Here, we reported an AIE-active polyamide with diphenylamine and tetraphenylethylene units, showing high fluorescence quantum yield up to 69.1% for the solid polymer film and stable electrochemical cycling stability. The polyamide exhibited reversible color and emission switching even in hundreds of cycles, and the fluorescence on/off contrast ratio was determined up to 417, which is the highest value to our knowledge. Furthermore, as the response time is vital for the real-life applications, to speed up the response of electrofluorochromism, a porous polymer film was readily prepared through a facile method, notably exhibiting high fluorescence contrast, long-term stability and obviously improved response, due to the sharply increased surface area. Therefore, the AIE-functionalization combining the porous structure strategy will synergistically and dramatically improve the electrofluorochromic performance, which will also promote their practical applications in the near future.

A novel semi-aromatic polyamide with bis(diphenylamino)-fluorene moieties was designed and synthesized, which exhibited highly stable electrochromic/electrofluorescent dual-switching properties.

Multiple stimuli-responsive fluorescent materials have gained increasing attention for their fundamental investigation and intelligent applications. In this work, we report design and synthesis of a novel polyamic acid bearing oligoaniline, triphenylamine, and fluorene groups, which served as sensitive units and fluorescence emission unit, respectively. The resulting polymer exhibits multiple stimuli-responsive fluorescence switching behavior triggered by redox species, pH, electrochemical, and pressure stimuli. Every fluorescence switching mechanism upon each stimulus was studied in detail. The interactions and energy transfer between sensitive units and emission unit are largely responsible for this fascinating fluorescent switching behavior. This work provides a deep understanding of the optical switching essence upon these stimuli, opening the way for the development of new fluorescent sensing applications.

Electrofluorochromic (EFC) materials have aroused great interest owing to their interesting ability of tuning fluorescence in response to the applied potential. However, some crucial characteristics, such as response speed, fluorescence contrast, and switching stability, are still not well realized to meet the requirements of practical applications. Herein, we designed and synthesized a novel polyamide-bearing aggregation-induced emission (AIE)-active tetraphenylethylene (TPE) and a highly conjugated triphenylamine (TPA) pendant group. The rational combination of the highly conjugated TPA and TPE caused the resultant polymer to exhibit highly integrated electrochromic (EC) and EFC performances including multiple color-changing (colorless to green to blue), fast response speed (1.8/1.1 s for EC and 0.4/2.9 s for EFC process), high fluorescence contrast (82 at the duration time of 20 s), and excellent long-term stability over 300 cycles. The strategy of AIE functionality by combing a highly conjugated redox unit demonstrates a synergistic effect to prepare high-performance emission/color dual-switchable materials, greatly promoting their applications in sensors, smart windows, and displays.

Porphyrin-graphene composites have attracted increasing attention due to a number of intriguing functions, and their photoelectrical and catalytic performances are expected to be modulated through different approaches. In the present study, a designed polymer based on phenyl sulfone, (p-amino)phenylhydroquinone, and a symmetrical dinaphthylporphyrin were covalently attached to a graphene oxide (GO) sheet. The formation of the nanohybrid was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Raman, ultraviolet-visible (UV-vis) absorption, steady and transient fluorescence spectroscopy techniques. The nonlinear optical and optical limiting performances of the hybrid were investigated using Z-scan measurements at 532 nm and 1064 nm. For comparison, a porphyrin functionalized GO hybrid was synthesized as a reference. At the same linear transmittance, the polymer functionalized GO exhibited a stronger optical limiting response and a larger nonlinear extinction coefficient than the individual GO, porphyrinated polymer, and porphyrin functionalized GO hybrid analogue, and its intrinsic photophysical mechanism was discussed in detail. More importantly, further improvement of its nonlinear optical properties can be achieved by the chemical reduction of the hybrid. The enhanced nonlinear optical performance originated from the effective combination of nonlinear scattering, reverse saturable absorption, and a possible photo-induced electron/energy transfer mechanism from donor porphyrin moieties in the polymer backbone to acceptor graphene. Our result might provide a new avenue for the development of graphene-porphyrin materials in the field of photocatalysis, nonlinear optics, and optoelectronic devices.

A series of novel organosoluble polyamides (4a–4e) bearing fluorene-based triphenylamine unit were prepared. These polyamides showed improved stability of electrochromic and electro-switchable fluorescence properties.

Electrochromic (EC)/electrofluorochromic (EFC) bifunctional materials are receiving great attention because of their promising applications in optoelectronic devices. However, the development of ideal EC/EFC bifunctional materials is still a great challenge because of the poor integration of EC/EFC performances (optical contrast, response speed, and switching stability). Herein, we reported two novel diphenylamine-based mixed valence (MV) polyamides (S-HPA and P-HPA) with spirobifluorene (2,7-positions) and pyrene (1,6-positions) as bridged fluorescence units, respectively, showing impressive cyclability and fluorescence contrast with rapid switching. Through the formation of an effective electronic coupling between the two nitrogen centers using spirobifluorene/pyrene bridges, we demonstrated that different bridges have significant effects on the thermal and electrooptical characteristics of polyamides. In addition to lower fluorescence quantum yield and glass transition temperature, the S-HPA exhibited superior cyclability (contrast change <3.4%/14% over 500/300 cycles for EC/EFC switching), higher color/fluorescence contrast (64%/304%), and faster switching time (<2.6 s), mainly owing to the shorter conjugated length and more twisted configuration of the spirobifluorene bridge. The design principle of MV polymers with fluorophore bridges proposed here will be a promising way to realize high-performance EC/EFC devices and will also provide new insights into their future development and applications.

A series of electrochromic and photoluminescenceactive polyamides 4a-4e were prepared from a novel dicarboxylic acid, N,N-di(4-carboxyphenyl)-2-amino-9,9-dimethylfluorene, and five diamines via a condensation polymerization. These polyamides were amorphous and readily soluble in many solvents. The glass transition temperatures were in the range of 281-339 8C and the 10% weight loss temperatures in nitrogen were in excess of 490 8C. The polyamides exhibited strong fluorescence in either solution or solid states. The polyamides 4a-4d showed reversible electrochemical redox with color changing from colorless to grey-green. Specially, the polyamide 4e with 2-diphenylamino-(9,9-dimethylamine) group in both diamine and dicarboxylic acid residues exhibited multicolored electrochromic behaviors. Furthermore, the fluorescence of these polyamides could be reversibly electroswitched with a high contrast up to 221.4, enabling their potential applications in dual-switching electrochromic/electrofluorescent materials. V C 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 213-222