C-H-activated Csp2-Csp3 diastereoselective gridization enables ultraviolet-emitting stereo-molecular nanohydrocarbons with mulitple H···H interactions.

Gridization is an emerging molecular integration technology that enables the creation of multifunctional organic semiconductors through precise linkages. While Friedel-Crafts gridization of fluorenols is potent, direct linkage among fluorene molecules poses a challenge. Herein, we report an achiral Pd-PPh3-cataylized diastereoselective (>99:1 d.r.) gridization based on the C-H-activation of fluorene to give dimeric and trimeric windmill-type nanogrids (DWGs and TWGs). These non-conjugated stereo-nanogrids showcase intramolecular multiple H…H interactions with a low field shift to 8.51 ppm and circularly polarized luminescence with high luminescent dissymmetry factors (|gPL | = 0.012). Significantly, the nondoped organic light-emitting diodes (OLEDs) utilizing cis-trans-TWG1 emitter present an ultraviolet electroluminescent peak at ~386 nm (CIE: 0.17, 0.04) with a maximum external quantum efficiency of 4.17%, marking the highest record among nondoped ultraviolet OLEDs based on hydrocarbon compounds and the pioneering ultraviolet OLEDs based on macrocycles. These nanohydrocarbon offer potential nanoscafflolds for ultraviolet light-emitting optoelectronic applications.

Structure-Property Relationship of Macrocycles in Organic Photoelectric Devices: A Comprehensive Review.

Macrocycles have attracted significant attention from academia due to their various applications in organic field-effect transistors, organic light-emitting diodes, organic photovoltaics, and dye-sensitized solar cells. Despite the existence of reports on the application of macrocycles in organic optoelectronic devices, these reports are mainly limited to analyzing the structure-property relationship of a particular type of macrocyclic structure, and a systematic discussion on the structure-property is still lacking. Herein, we conducted a comprehensive analysis of a series of macrocycle structures to identify the key factors that affect the structure-property relationship between macrocycles and their optoelectronic device properties, including energy level structure, structural stability, film-forming property, skeleton rigidity, inherent pore structure, spatial hindrance, exclusion of perturbing end-effects, macrocycle size-dependent effects, and fullerene-like charge transport characteristics. These macrocycles exhibit thin-film and single-crystal hole mobility up to 10 and 26.8 cm2 V-1 s-1, respectively, as well as a unique macrocyclization-induced emission enhancement property. A clear understanding of the structure-property relationship between macrocycles and optoelectronic device performance, as well as the creation of novel macrocycle structures such as organic nanogridarenes, may pave the way for high-performance organic optoelectronic devices.

Spiro-based diamond-type nanogrids (DGs) via two ways: 'A1B1'/'A2 + B2' type gridization of vertical spiro-based fluorenol synthons.

Regular or well-defined nanogrids with atomically precise extension sites offer an opportunity for covalent nano-architectures as well as frameworks. Previously, we discovered organic nanogrids based on the 2,7-linkage of fluorene via Friedel-Crafts gridization. However, the regularity of nanogrids is not always based on the actual molecular backbone, which leads to ineffective linkage for the more regular complex nanogrids such as nano-windows. Herein, we report the introduction of spirobifluorene, which has more orthogonal shapes, to fix the backbone of nanogridons with regards to the diarylfluorenes. The diamond-type nanogridons (DGs) obtained as a result have the potential feature of cross extension, which is different from their ladder-type counterparts, although they both have four well-defined extension sites. In order to screen efficient monogridon modules, we designed two types of DGs (spiro[fluorene-9,8'-indeno[2,1-b]thiophene] (SFIT)-based DGs-1 and spirobifluorene-based DGs-2) and compared their synthetic routes. The results show that the Friedel-Crafts (F-C) gridization of the A1B1 synthon (A1B1 mode) offers DGs-1 in 44-50% yields, while the F-C gridization of A2 + B2 synthons (A2 + B2 mode) is more efficient and gives DGs-2 in 64% yield. Furthermore, unlike in the A1B1 mode, the dehydroxylated byproduct and linear polymers were not observed in the A2 + B2 mode.

Stereoselective gridization and polygridization with centrosymmetric molecular packing.

The gridarenes, with well-defined edges and vertices, represent versatile nanoscale building blocks for the installation of frameworks and architectures but suffer from difficulty in stereoselective control during their synthesis. Here we report a diastereoselective gridization of superelectrophilic diazafluorene-containing substrates (AmBn) with crescent shapes into Drawing Hands grids (DHGs). The meso-selectivity reaches 75.6% diastereomeric excess (de) during the gridization of A1B1-type substrates and maintains ~80% de during the polygridization of A2B2-type monomers. Such stereocontrol originates from the centrosymmetric molecular packing of two charge-delocalized superelectrophiles with synergistically π-π stacking attractions and coulombic repulsions. As meso-stereoregular structures show 20∼30 nm in length, the rigid ring/chain-alternating polygrids have a Mark-Houwink exponent of 1.651 and a molecular weight (M) dependence of the hydrodynamic radius Rh ∼ M1.13. Via the simulation of chain collapse, meso-configured polygridarenes still adopt rod-like conformations that facilitate the high rigidity of organic nanopolymers, distinguished from toroid backbones of rac-type polygrids.