The quest for planar sp2-hybridized carbon allotropes other than graphene, such as graphenylene and biphenylene networks, has stimulated substantial research efforts because of the materials’ predicted mechanical, electronic, and transport properties. However, their syntheses remain challenging given the lack of reliable protocols for generating nonhexagonal rings during the in-plane tiling of carbon atoms. We report the bottom-up growth of an ultraflat biphenylene network with periodically arranged four-, six-, and eight-membered rings of sp2-hybridized carbon atoms through an on-surface interpolymer dehydrofluorination (HF-zipping) reaction. The characterization of this biphenylene network by scanning probe methods reveals that it is metallic rather than a dielectric. We expect the interpolymer HF-zipping method to complement the toolbox for the synthesis of other nonbenzenoid carbon allotropes.

The rapid development of organic electronics is closely related to the availability of molecular materials with specific electronic properties. Here, we introduce a novel synthetic route enabling a unilateral functionalization of acenes along their long side, which is demonstrated by the synthesis of 1,2,10,11,12,14‐hexafluoropentacene (1) and the related 1,2,9,10,11‐pentafluorotetracene (2). Quantum chemical DFT calculations in combination with optical and X‐ray absorption spectroscopy data indicate that the single‐molecule properties of 1 are a connecting link between the organic semiconductor model systems pentacene (PEN) and perfluoropentacene (PFP). In contrast, the crystal structure analysis reveals a different packing motif than for the parent molecules. This can be related to distinct F⋅⋅⋅H interactions identified in the corresponding Hirshfeld surface analysis and also affects solid‐state properties such as the exciton binding energy and the sublimation enthalpy.

Optoelectronic properties of molecular solids are important for organic electronic devices and are largely determined by the adopted molecular packing motifs. In this study, we analyzed such structure‐property relationships for the partially regioselective fluorinated tetracenes 1,2,12‐trifluorotetracene, 1,2,10,12‐tetrafluorotetracene and 1,2,9,10,11‐pentafluorotetracene that were further compared with tetracene and perfluoro‐tetracene. Quantum chemical DFT calculations in combination with optical absorption spectroscopy data show that the frontier orbital energies are lowered with the degree of fluorination, while their optical gap is barely affected. However, the crystal structure changes from a herringbone packing motif of tetracene towards a planar stacking motif of the fluorinated tetracene derivatives, which is accompanied by the formation of excimers and leads to strongly red‐shifted photoluminescence with larger lifetimes.

As traightforward method for post-complexation derivatizations of diastereo-and enantiomerically pure biscyclometalated benzoxazole and benzothiazole iridium(III) complexes is reported.T riflate-and bromine-functionalized iridium(III) complex dimers, represented as [Ir(m-Cl)(C^N) 2 ] 2 , were converted to the corresponding diastereomeric complexes, represented as Ir(C^N) 2 (N^O), using readily available chiral salicyloxazolines and salicylthiazolines as ancillary ligands, which are represented as N^O. The Ir(C^N) 2 (N^O) complexes, formed as mixtures of diastereomers, were then resolved by flash chromatography and the diastereomerically pure complexes Ir(C^N) 2 (N^O) subjected to Suzukic rosscouplings. The post-complexation cross-couplings proceed without affecting the metal-located stereocenter and hence provide post-complexation derivatized non-racemic iridium(III) complexes, which were not easily accessible with previousm ethods. This strategy expands the toolboxt o accessf unctionalized non-racemic iridium(III) complexes for diversea pplicationsi nt he life sciences,m aterials sciences, and catalysis.

The crystallization and polymorph control of rigid polar molecules by solvent polarity was investigated for the case of 1,2,9,10,11-pentafluorotetracene (F 5 TET), an extended π-conjugated molecule with large in-plane dipole moment. Liquid assisted crystallization from polar solvents results in a dipoleparallel molecular arrangement with a crisscross packing. By contrast, nonpolar solvents lead to a more stable polymorph, which exhibits a dipole-antiparallel arrangement with a slip-stacked packing. Since for both polymorphs no solvents are incorporated in the crystal lattice, we attribute the different growth modes to a screening of the electrostatic forces by the solvent during nucleation. The results emphasize that solvent polarity must be considered when exploring the polymorphic landscape of molecular materials, which is particularly important for organic semiconductors that typically consist of π-conjugated molecules with rather low solubility, thus hampering normal solution crystallization.