No abstract

Designing structural order in electronically active organic solids remains agreat challenge in the field of materials chemistry.Now,2Dpoly(arylene vinylene)s prepared as highly crystalline covalent organic frameworks (COFs) by basecatalyzeda ldol condensation of trimethyltriazine with aromatic dialdehydes are reported. The synthesized polymers are highly emissive (quantum yield of up to 50 %), as commonly observed in their 1D analogues poly(phenylene vinylene)s.The inherent well-defined porosity (surface area ca. 1000 m 2 g À1 , pore diameter ca. 11 for the terephthaldehyde derived COF-1) and 2D structure of these COFs also present an ew set of properties and are likely responsible for the emission color, which is sensitive to the environment. COF-1 is highly hydrophilic and reveals ad ramatic macroscopic structural reorganization that has not been previously observed in framework materials.

The black crystalline (aza)­triangulene-based covalent organic framework TANG-COF was synthesized from its trinitro-TANG precursor via a one-pot, two-step reaction involving Pd-catalyzed hydrogenation and polycondensation with an aromatic dialdehyde. High crystallinity and permanent porosity of the layered two-dimensional (2D) structure were established. The rigid, electron-rich trioxaazatriangulene (TANG) building block enables strong π-electron interactions manifested in broad absorptions across the visible and NIR regions (E g ≈ 1.2 eV). The high HOMO energy of TANG-COF (−4.8 eV) enables facile p doping, resulting in electrical conductivity of up to 10–2 S/cm and room-temperature paramagnetic behavior with a spin concentration of ∼10%. DFT calculations reveal dispersion of the highest occupied band both within the 2D polymer layers (0.28 eV) and along their π-stacked direction (0.95 eV).

We report the first transformation between crystalline vinylene-linked two-dimensional (2D) polymers and crystalline cyclobutane-linked three-dimensional (3D) polymers. Specifically, absorption-edge irradiation of the 2D poly(arylenevinylene) covalent organic frameworks (COFs) results in topological [2+2] cycloaddition cross-linking the π-stacked layers in 3D COFs. The reaction is reversible and heating to 200C leads to a cycloreversion while retaining the COF crystallinity. The resulting difference in connectivity is manifested in the change of mechanical and electronic properties, including exfoliation, blue-shifted UV-Vis absorption, altered luminescence, modified band structure and different acid-doping behavior. The Li-impregnated 2D and 3D COFs show a significant ion conductivity of 1.8×10 −4 S/cm and 3.5×10 −5 S/cm, respectively. Even higher room temperature proton conductivity of 1.7×10 -2 S/cm and 2.2×10 -3 S/cm was found for H2SO4-treated 2D and 3D COFs, respectively.

We report a series of highly emissive azatriangulenetrione (TANGO) solids in which the luminescent properties are controlled by engineering the molecular packing by adjusting the steric size of substituents. The co‐alignment of “phosphorogenic” carbonyl groups within the π‐stacks results in an almost pure triplet emission in HTANGO, TCTANGO, TBTANGO and TITANGO, while their rotation by ≈60° in the sterically hindered tBuTANGO leads to an almost pure singlet emission. Despite strong π‐interactions, aggregation‐induced quenching and triplet–triplet annihilation are avoided in HTANGO and TCTANGO which display efficient phosphorescence in the solid state. To our knowledge, HTANGO with the solid‐state phosphorescence quantum yield of 42 % at room temperature is the most efficient phosphor composed of the 1st/2nd raw elements only.