Front Cover: In article number 1900289 by R. M. Gamini Rajapakse, Davita L. Watkins, and co‐workers, electrochemical copolymerization affords near infrared‐II (100–1700 nm) absorbing copolymers with intrinsic conductivities over a wide potential window, even where it is nominally undoped. This study showcases the advantages of electro‐polymerization toward tailoring of next generation optoelectronic materials.
Doxorubicin (DOX) is an anticancer drug commonly used in treating cancer; however, it has severe cytotoxicity effects. To overcome both the adverse effects of the drug and mineral deficiency (i.e., hypomagnesemia) experienced by cancer patients, we have developed magnesium oxide (MgO) nanoflakes as drug carriers and loaded them with DOX for use as a targeted drug delivery (TDD) system for potential application in cancer therapy. The synthesis employed herein affords pure, highly porous MgO nanoparticles that are void of the potentially harmful metal contaminants often discussed in the literature. Purposed for dual therapy, the nanoparticles exhibit an impressive 90% drug loading capacity with pH dependent drug releasing rates of 10% at pH 7.2, 50.5% at pH 5.0, and 90.2% at pH 3. Results indicate that therapy is achievable via slow diffusion where MgO nanoflakes degrade (i.e., dissolve) under acidic conditions releasing the drug and magnesium ions to the cancerous region. The TDD system therefore minimizes cytotoxicity to healthy cells while supplying magnesium ions to overcome hypomagnesemia.
Thienothiadiazole‐bisthiophene (TTDT2) and diketopyrrolo–pyrrole–bisthiophene (DPPT2) are successfully electro‐copolymerized with terthiophene (T3) as an initiator and linker at low oxidative potentials. AC impedance analysis, absorption spectroscopy, and elemental composition via SEM‐EDX support the formation of donor–acceptor (D–A) type alternating block copolymers, poly(T3‐TTDT2), and poly(T3‐DPPT2). Unique optical properties that span into the near infrared‐II(>1000 nm) region and inherent electrical conductivity at the p‐type regime, n‐type regime, and in between the two regimes (i.e., typical insulator region) are observed. This study showcases the advantages of electro‐polymerization toward tailoring of next generation opto‐electronic materials.
Using electro-copolymerization as a versatile tool in synthesizing alternating and block copolymers, we have designed conjugation polymers with unique optical properties and excellent conductivities in comparison to conventional conjugated polymers.
Donor-acceptor (DÀ A) polymers have excellent electronic and optical properties that allow for their use in multiple areas of research, ranging from field-effect transistors to biosensing. However, traditional chemical polymerization strategies to form DÀ A polymers often require extensive purification and generate large amounts of waste. Electro-copolymerization of complex isoindigo-based copolymers is explored as a way to overcome traditional synthetic challenges. Herein, the electropolymerization and characterization of four isoindigo-based DÀ A copolymers are studied with: II-EDOT-T 3 , II-Thio-T 3 , II-Thio-T 3-TTDT 2 , and II-EDOT-T 3-TTDT 2. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis are used to confirm the composition of the polymers. Electrochemical impedance measurements show electron-transport resistance (R e) values as low as 74.7 Ω at selected potentials, indicating that highly conductive copolymers are present. These p-doped polymers exhibit absorption bands within the near-infrared region (NIR) with optical band gaps as low as 0.790 eV. Results confirm the electro-synthesized DÀ A copolymers exhibit excellent optical properties in the solid state and enhanced conductivity relative to conventional polymers; thus, affording materials with uses in a broad spectrum of applications.
Electropolymerization has become a convenient method for synthesizing and characterizing complex organic copolymers having intrinsic electronic conductivity, including the donor (D)–acceptor (A) class of electronically conducting polymers (ECPs).
The electrochromic properties and application of electronically conducting polymers (ECPs) (PTRPZ-EDOT) consisting of a 3,4ethylenedioxythiophene (EDOT) and the heteroacene-based molecular scaffold, 6H-pyrrolo[3,2-b:4,5-b′] bis [1,4] benzothiazine (TRPZ), are reported. Known for its high electron mobility and conducting properties, the novel TRPZ scaffold was synthesized to possess two EDOT molecules termini affording TRPZ-EDOT. Electropolymerization of TRPZ-EDOT resulted in remarkable spectroscopic and conductive properties suitable for electrochromic device fabrication. Using atomic force microscopy (AFM), the average surface roughness and surface topography of PTRPZ-EDOT polymer thin films were determined. Spectroelectrochemical data showed that the polymer achieved switching times of 4.07 (coloration) and 0.47 s (bleaching) at 539 nm. The PTRPZ-EDOT film exhibits an optical contrast of 36−44% at 539 nm between its neutral and colored states, respectively. The NIR region from 1000 to 1700 nm shows the appearance of charge carrier bands with a 0−1 V potential range. An electrochromic device was successfully fabricated from PTRPZ-EDOT, showcasing the potential and applicability of the polymer material for advanced technologies such as smart windows, flexible electrochromic screens, and energy storage devices.
The challenges faced with current fluorescence imaging agents have motivated us to study two nanostructures based on a hydrophobic dye, 6H-pyrrolo[3,2-b:4,5-b’]bis [1,4]benzothiazine (TRPZ). TRPZ is a heteroacene with a rigid, pi-conjugated structure, multiple reactive sites, and unique spectroscopic properties. Here we coupled TRPZ to a tert-butyl carbamate (BOC) protected 2,2-bis(hydroxymethyl)propanoic acid (bisMPA) dendron via azide-alkyne Huisgen cycloaddition. Deprotection of the protected amine groups on the dendron afforded a cationic terminated amphiphile, TRPZ-bisMPA. TRPZ-bisMPA was nanoprecipitated into water to obtain nanoparticles (NPs) with a hydrodynamic radius that was <150 nm. For comparison, TRPZ-PG was encapsulated in pluronic-F127 (Mw = 12 kD), a polymer surfactant to afford NPs almost twice as large as those formed by TRPZ-bisMPA. Size and stability studies confirm the suitability of the TRPZ-bisMPA NPs for biomedical applications. The photophysical properties of the TRPZ-bisMPA NPs show a quantum yield of 49%, a Stokes shift of 201 nm (0.72 eV) and a lifetime of 6.3 ns in water. Further evidence was provided by cell viability and cellular uptake studies confirming the low cytotoxicity of TRPZ-bisMPA NPs and their potential in bioimaging.
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