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Polymers containing the 1,4-diketo-pyrrolo[3,4-c]pyrrole (diketopyrrolopyrrole, DPP) unit are highly desirable for optoelectronic devices. However, the requirements for the substituents flanking the DPP unit at the 3,6-positions are limited to aryl groups due to the lack of synthetic methods to prepare other substituted DPP. This paper describes the synthesis, characterization, and application of the first vinyl-flanked DPP polymers: DPP-vinyl-thiophene-vinyl (PDPPVTV) and DPP-vinyl-thiophene-thiophene (PDPPVTT). The position of the vinyl group is varied to determine its effect on the physical and optoelectrical properties of the polymers. The semicrystalline polymers record moderate molecular weights (Mn∼ 25–30 kDa), good solubility in chloroform, and high thermal stabilities (Tdonset ∼ 400 °C). Both polymers have broad absorption bands in the solid state (abs λmax∼ 800 nm) that extend into the near-infrared (NIR) region (900–1000 nm). PDPPVTThas two orders of magnitude higher hole mobility than PDPPVTV(0.25 vs 0.0018 cm2V–1s–1) and is used as a coating material in a MoS2FET device. The PDPPVTT/2D MoS2hybrid device shows higher photoresponsivity in the NIR region (103A/W at 800 nm and 102A/W at 1050 nm) than the pristine MoS2photodetector (102A/W at 800 nm and 0 A/W at 1050 nm).

An effective design strategy with an efficient synthetic route to xanthene-based far-red to near-infrared dyes is reported. The dyes were prepared by the Suzuki cross-coupling of the electron-poor fluorescein ditriflate with the electron-rich boronic acid/ester-functionalized pyrrole (2C/3C) and indole (2D/3D) moieties. Upon treatment with trifluoroacetic acid, the closed nonfluorescent forms of the dyes (2Cand 2D) ring-opened to their fluorescent forms (3Cand 3D). The absorption maxima were 665 and 704 nm, while the emission maxima were 717 and 719 nm for 3Cand 3D, respectively. The closed forms of the dyes were soluble in chloroform and acetonitrile. To test the efficacy of the dyes as probes, a turn-off fluoride ion probe was prepared from 3C, which consisted of a silyl ester receptor. The probe responded strongly to low concentrations of fluoride, carbonate, and acetate ions, weakly to phosphate ions, but not to the other halogens. Moreover, the probe can detect the minimum concentration of F–in water.

Side chain alkyl groups have become the standard for incorporating solubilizing groups into conjugated polymers. However, the variety of alkyl groups available and their location on the polymer’s backbone can contribute to the packing of the polymer chains in many different ways, resulting in many different morphologies in the polymer that can affect its properties and performances. In this paper, we investigate the effects on the conductivity of nine phenothiazine-containing polyaniline derivatives (P1–P9) with alkyl or aryl side chains on the phenothiazine core while also varying the number of methyl groups on the p-phenylenediamine unit. 1H nuclear magnetic resonance spectroscopy, ultraviolet–visible spectroscopy, differential scanning calorimetry, scanning electron microscopy, atomic force microscopy, and wide-angle X-ray scattering (WAXS) were all used to study the polymers’ structures, physical and thermal properties, and morphologies. The t-butylphenyl substituent on the phenothiazine core seems to provide more rigidity in the polymer’s backbone resulting in higher Tgfor series 3, while series 2 containing the 2-hexyldecyl-substituted polymers had the lowest Tg, which is attributed to the large volume of the side chain, that limits interchain interactions. Consequently, series 2 had the lowest conductivity. However, the strongest effect on the conductivity was seen from the tetramethyl groups on the PPDA unit, which resulted in the lowest conductivity in each series due to torsional strain (twisting) in the polymer’s backbone. The WAXS data suggest mostly amorphous films; thus, the conductivity in these materials seems to be dominated by a multiscale charge transport phenomenon that occurs in amorphous conjugated materials. Our results will aid in the understanding of side chain engineering of PANI derivatives for their optimum performances.

A NIR II emissive dye was synthesized by the C–H bond functionalization of 1-methyl-2-phenylindolizine with 3,6-dibromoxanthene. The rhodindolizine (RhIndz) spirolactone product was nonfluorescent; however, upon opening of the lactone ring by the formation of the ethyl ester derivative, the fluorophore absorbs at 920 nm and emits at 1092 nm, which are both in the NIR II region. In addition, 4-cyanophenyl- (CNRhIndz) and 4-methoxyphenyl-substituted rhodindolizine (MeORhIndz) could also be prepared by the C–H activation reaction.

This manuscript describes an unprecedented and efficient synthesis of a new DPP scaffold, 2,5-dibutyl-3,6-dimethyl-1H,2H,4H,5H-pyrrolo[3,4-c]pyrrole-1,4-dione (DMDPP), containing methyl groups at the 3,6-positions as a precursor to preparing 3,6-divinyl-substituted DPP compounds. Subsequently, following the synthesis of DMDPP, we performed an efficient and mild C–H functionalization of the methyl groups with a variety of aromatic aldehydes to synthesize the first examples of 3,6-divinyl-substituted DPP compounds in moderate to good yields.

Alternating donor–acceptor copolymers are important materials with readily tunable optical and electronic properties. Direct arylation polymerization (DArP) is emerging as an attractive synthetic methodology for the synthesis of these polymers, avoiding the use of prefunctionalized building blocks. However, challenges remain in achieving well‐defined structure, high molecular weight, and impurity‐free polymers. Herein, a study to synthesize three well‐defined donor–acceptor copolymers through DArP is presented. Comparison of 1H NMR and 13C NMR, as well as optical and electrochemical properties analysis for the polymers and corresponding oligomers provides evidence for the regioregular structure of the polymers. On the basis of the chemical structure of poly(IIDCBT) and the solution electrochemical studies we surmised poly(IIDCBT) could potentially be an electron transport material for organic field‐effect transistors (OFETs), and we determined an electron mobility of 1.2×10−3cm2V−1s−1for this material. Direct arylation polymerization: A detailed study of palladium catalyzed direct arylation reactions of dicyanobenzothiadiazole for the synthesis of small molecule oligomers and polymers is described. Optical and electronic properties of the resulting materials are presented.

The article discusses immunization information system assessments done in Kenya in 2015 and in Ghana in 2016 using a new World Health Organization (WHO) and U.S. Centers for Disease Control and Prevention assessment methodology. Topics mentioned include the attributes of high-quality immunization information systems, data quality challenges common to Kenya and Ghana, and the Data Quality Audit methodology developed by WHO in 2001.

•Household contact remains a major source of transmission of COVID-19.•Sleeping in the same bedroom as the primary case increases the odds of SARS-CoV-2 infection.•Eating food prepared by the primary case increases the odds of SARS-CoV-2 infection.•Household dimension ≤2,000 square feet increases the odds of sleeping in the same bedroom.•Innovative mitigation efforts are needed for feasibility and adherence in households.

Few xanthene-based near-infrared (NIR) photoacoustic (PA) dyes with absorbance >800 nm exist. As accessibility to these dyes requires long and tedious synthetic steps, we designed a NIR dye (XanthCR-880) with thienylpiperidine donors and a xanthene acceptor that is accessible in 3–4 synthetic steps. The dye boasts a strong PA signal at 880 nm with good biological compatibility and photostability, yields multiplexed imaging with an aza-BODIPY reference dye, and is detected at a depth of 4 cm.

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Several letters to the editor are presented in response to articles published in previous issues, including "Trees Are the Ark That Can Save Us" in the November 2007 issue, "Wellspring of Courage: International Leader Zainab Salbi" in the July 2007 issue and a response by the editors to a letter to the editor about yoga and multiple sclerosis.

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