Carlos

A novel non-fullerene electron acceptor (ITIC) that overcomes some of the shortcomings of fullerene acceptors, for example, weak absorption in the visible spectral region and limited energy-level variability, is designed and synthesized. Fullerene-free polymer solar cells (PSCs) based on the ITIC acceptor are demonstrated to exhibit power conversion efficiencies of up to 6.8%, a record for fullerene-free PSCs.

π-Extended thiadiazoles 4–8 fused with various electron-donating heteroaromatic moieties have been designed and synthesized. Just like thiadiazoles 1–3 synthesized previously, 4–8 exhibit intramolecular charge-transfer (CT) interactions, moderate-to-good fluorescence quantum yields of up to 0.78, and electrochemical amphoterism. In comparison with 1–3, the benzannulation in thiadiazoles 4–7 moderately extends the π conjugation and significantly increases the stability of the cationic species formed upon electrochemical oxidation. The fluorescence quantum yields increase remarkably from 3 to 6 and 7 due to the efficient suppression of nonradiative intersystem crossing resulting from the benzannulation. The properties of 4–8 strongly reflect the different species annulated to the pyrrole rings, namely benzothiophene, naphthalene, and benzofuran. Eleven crystals, including poly- and pseudopolymorphic crystals of 1 (1-Crys.(Y) and 1-Crys.(G)), 2 (2-Crys.(O) and 2-Crys.(G)), 4 (4-Crys.(O) and 4-Crys.(G)), and 6 (6-Crys.(O) and 6-Crys.(G)), were obtained and characterized by X-ray crystallography. The fluorescence colors and efficiencies are distinct for each poly- and pseudopolymorph of 1, 2, 4, and 6. It has been suggested that both the extent of the electronic interactions in the π-stacked dimers and the presence of excitonic interactions originating in the 1D face-to-face slipped columns affect the fluorescence wavelengths of the poly- and pseudopolymorphs.

π-Extended thiadiazoles: The photophysical and electrochemical properties of a series of π-extended thiadiazoles fused with electron-donating heteroaromatic moieties are disclosed. These compounds form poly- and pseudopolymorphic crystals, and the fluorescence properties in the crystalline state are significantly affected by the molecular arrangement (see figure).

The synthesis of metal–organic frameworks with large three-dimensional channels that are permanently porous and chemically stable offers new opportunities in areas such as catalysis and separation. Two linkers (L1=4,4′,4′′,4′′′-([1,1′-biphenyl]-3,3′,5,5′-tetrayltetrakis(ethyne-2,1-diyl)) tetrabenzoic acid, L2=4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid) were used that have equivalent connectivity and dimensions but quite distinct torsional flexibility. With these, a solid solution material, [Zr₆O₄(OH)₄(L1)_2.6(L2)_0.4]⋅(solvent)_x, was formed that has three-dimensional crystalline permanent porosity with a surface area of over 4000 m² g⁻¹ that persists after immersion in water. These properties are not accessible for the isostructural phases made from the separate single linkers.

Two linkers of equivalent connectivity but quite distinct torsional flexibility are used to produce [Zr₆O₄(OH)₄(L1)_2.6(L2)_0.4]⋅(solvent)_x that combines both structural and chemical stability in a metal–organic framework. Such a combination is not accessible for the single-linker isostructural phases. The resulting Zr-based MOF has three-dimensional channels and a high surface area of 4184 m² g⁻¹.