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We describe here a facile synthesis of 9-arylfluorenes and spirobifluorenes from readily available 1,1-diarylmethylamines and iodoarenes through Pd-cataylsed C(sp2)–H arylation and a sequential deaminative annulation. The reaction features high efficiency and simplicity of operation, constituting an interesting shortcut to access fluorene compounds. [ABSTRACT FROM AUTHOR]

An efficient [3+3] benzannulation of Morita–Baylis–Hillman carbonates with 1-indanylidenemalononitrile was achieved under metal-free reaction conditions selectively delivering a wide range of functional multi-substituted fluorene or fluorenone compounds in high yields, respectively (up to 86% yield). Moreover, experiments and quantum chemical calculations were also performed to study the mechanism of the transformation. [ABSTRACT FROM AUTHOR]

The synthesis of [1,1′-bis(o-carboranyl)]boranes was achieved through the deprotonation of 1,1′-bis(o-carborane) reagents followed by salt metathesis with (iPr)2NBCl2. X-ray crystallography confirms planar central BC4 rings and Gutmann–Beckett studies reveal an increase in Lewis acidity at the boron center in comparison to their biphenyl congener, 9-borafluorene. [ABSTRACT FROM AUTHOR]

Open-shell diradicaloids have been intensively investigated recently due to their attractive and unique optical, electronic and magnetic properties. However, open-shell diradicaloids with non-planar conjugated frameworks are less studied, especially helical-shaped π systems. In this work, we synthesized tetraindeno-based singlet biradicals in a helical geometry, bridged by a curved cyclobutenyl o-quinodimethane molecule. Large diradical characters and extremely small singlet–triplet energy gaps, as well as unusual half-field transitions (forbidden ΔMs = 2) were revealed for these 3D diradicals. [ABSTRACT FROM AUTHOR]

The future of 89Zr-based immuno-PET is reliant upon the development of new chelators with improved stability compared to the currently used deferoxamine (DFO). Herein, we report the evaluation of the octadentate molecule DFO-HOPO (3) as a suitable chelator for 89Zr and a more stable alternative to DFO. The molecule showed good potential for the future development of a DFO-HOPO-based bifunctional chelator (BFC) for the radiolabelling of biomolecules with 89Zr. This work broadens the selection of available chelators for 89Zr in search of improved successors to DFO for clinical 89Zr-immuno-PET. [ABSTRACT FROM AUTHOR]

We report a novel fluorene-based polyelectrolyte carrying hexafluorophosphate counterions to dope into PCBM as an electron transporting layer (ETL). Inverted planar heterojunction perovskite solar cells showed improved photovoltaic performance, including short-circuit current density, the fill factor, and power conversion efficiency, compared with the one using pure PCBM as an ETL. [ABSTRACT FROM AUTHOR]

Two types of one-handed exact helical polymers, coil- and screw-shaped polymers, were synthesized by the two-point-covalent-linking protocol using C2-chiral spirobifluorene (SBF) and C2- or Cs-symmetric anthraquinone spacers. Central to this protocol is a new aromatic ring-forming reaction based on the stepwise reductive cyclization of bis(aryloxy group)-substituted anthraquinone derivatives. The helical structures of the polymers annulated by aromatic skeletons exhibited high thermal stability attributed to the rigid C2-chiral SBF units and the covalently two-point-connected structure. [ABSTRACT FROM AUTHOR]

The biosynthesis of diazobenzofluorene kinamycins requires a hitherto uncharacterized B-ring contraction. Via detailed genetic and enzymatic analyses we unambiguously characterized the conserved pairs of oxidases, AlpJ and AlpK homologs, as nature's machinery for benzofluorenone formation, which paves the way for the investigation of the following diazo assembly. [ABSTRACT FROM AUTHOR]

Polymorphism is observed in 9,9-diarylfluorene-based organic semiconductors. The effects of rich phase behavior on the charge transport and photoluminescence properties of these semiconductors are investigated. Polymorphism control is a rational way to tailor the optoelectronic functions of their films. [ABSTRACT FROM AUTHOR]

Fluorene-based bis(dioxaborole)s and a poly(dioxaborole) were used to optically detect Lewis bases. Studies of the binding mechanism and signal transduction indicated that the response from these dioxaboroles was sensitive, reversible and cross-reactive. The polymer exhibited enhanced response due to extended conjugation through the dioxaboroles. [ABSTRACT FROM AUTHOR]

Two types of exact helical polymers, screw-shaped and coil-shaped, consisting of right-angled C2-chiral 9,9′-spirobifluorene skeletons were selectively synthesized based on a two-point-connection protocol by controlling the connecting direction between the monomers. [ABSTRACT FROM AUTHOR]

The back cover page of the February 2016 issue of the journal "Chemical Communications" is presented.