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The potency of heteroatom-doping in reshaping optoelectronic properties arises from the distinct electronegativity variations between heteroatoms and carbon atoms. By incorporating two heteroatoms with differing electronegativities (e.g., B = N), not only is the architectural coherence of π-conjugated systems retained, but also dipolar traits are introduced, accompanied by unique intermolecular interactions absent in their all-carbon analogs. Another burgeoning doping strategy, featuring the heteroatom–boron–heteroatom motif (X–B–X, where X = N, O), has captured growing attention. This configuration's coexistence of the boron-heteroatom unit and an isolated heteroatom stimulates mutual modulation in the dipole of the boron-heteroatom unit and the heteroatom's electronegativity. In this Feature article, we present an encompassing survey of XBX-doped π-conjugated systems, elucidating how the integration of the X–B–X unit induces transformative structural and property changes within π-conjugated systems. [ABSTRACT FROM AUTHOR]

The incorporation of heteroatoms and/or heptagons as the defects into helicenes expands the variety of chiroptical materials with novel properties. However, it is still challenging to construct novel boron‐doped heptagon‐containing helicenes with high photoluminescence quantum yields (PLQYs) and narrow full‐width‐at‐half‐maximum (FWHM) values. We report an efficient and scalable synthesis of a quadruple helicene 4Cz‐NBN with two nitrogen‐boron‐nitrogen (NBN) units and a double helicene 4Cz‐NBN‐P1 bearing two NBN‐doped heptagons, the latter could be formed via a two‐fold Scholl reaction of the former. The helicenes 4Cz‐NBN and 4Cz‐NBN‐P1 exhibit excellent PLQYs up to 99 % and 65 % with narrow FWHM of 24 nm and 22 nm, respectively. The emission wavelengths are tunable via stepwise titration experiments of 4Cz‐NBN‐P1 toward fluoride, enabling distinguished circularly polarized luminescence (CPL) from green, orange (4Cz‐NBN‐P1‐F1) to yellow (trans/cis‐4Cz‐NBN‐P1‐F2) with near‐unity PLQYs and broader circular dichroism (CD) ranges. The five structures of the aforementioned four helicenes were confirmed by single crystal X‐ray diffraction analysis. This work provides a novel design strategy for construction of non‐benzenoid multiple helicenes exhibiting narrow emissions with superior PLQYs. [ABSTRACT FROM AUTHOR]

The incorporation of heteroatoms and/or heptagons as the defects into helicenes expands the variety of chiroptical materials with novel properties. However, it is still challenging to construct novel boron‐doped heptagon‐containing helicenes with high photoluminescence quantum yields (PLQYs) and narrow full‐width‐at‐half‐maximum (FWHM) values. We report an efficient and scalable synthesis of a quadruple helicene 4Cz‐NBN with two nitrogen‐boron‐nitrogen (NBN) units and a double helicene 4Cz‐NBN‐P1 bearing two NBN‐doped heptagons, the latter could be formed via a two‐fold Scholl reaction of the former. The helicenes 4Cz‐NBN and 4Cz‐NBN‐P1 exhibit excellent PLQYs up to 99 % and 65 % with narrow FWHM of 24 nm and 22 nm, respectively. The emission wavelengths are tunable via stepwise titration experiments of 4Cz‐NBN‐P1 toward fluoride, enabling distinguished circularly polarized luminescence (CPL) from green, orange (4Cz‐NBN‐P1‐F1) to yellow (trans/cis‐4Cz‐NBN‐P1‐F2) with near‐unity PLQYs and broader circular dichroism (CD) ranges. The five structures of the aforementioned four helicenes were confirmed by single crystal X‐ray diffraction analysis. This work provides a novel design strategy for construction of non‐benzenoid multiple helicenes exhibiting narrow emissions with superior PLQYs. [ABSTRACT FROM AUTHOR]

The optimal selection of sweet spots for the exploitation of tight oil reservoirs is very important when formulating a development programme. Sweet spots for the exploitation of tight oil reservoirs are closely related to reservoir quality, hydrocarbon source rock quality and completion quality. In this study, criteria for the classification of sweet spots are established using a tight reservoir of fine sandstone in the first member of the Qingshankou Formation in Daqingzijing Oilfield, China as the study site. The results indicate that the vast majority of the research area includes type I and type II sweet spots. Type I sweet spots are located in the west and northwest of the research area and in the central region around wells H71 and H116; type II are located in the northeast and south of the research area, as well as in the region around the type I sweet spots. In the well region of type I sweet spots, the oil/gas is relatively enriched, and the fracability of the reservoir stratum is strong; these are key areas for tight oil development in the research area. Comparison of the evaluation results with well testing data indicates that the effect of well fracturing is obvious for type I sweet spots and the corresponding oil yield is high. The results of well fracturing are also adequate for type II sweet spots and the oil output can reach industry standards, although the corresponding yield is relatively low. Wells in non-sweet spots are unlikely to be fractured successfully, and even if they are, the oil output cannot reach industry standards. [ABSTRACT FROM AUTHOR]