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Covalent triazine frameworks (CTFs) with aromatic triazine linkages have recently received increasing interest for various applications because of their rich nitrogen content and high chemical stability. Owing to the strong aromatic C=N bond and high chemical stability, only a few CTFs are crystalline, and most CTFs are amorphous. Herein we report a new general strategy to give highly crystalline CTFs by in situ formation of aldehyde monomers through the controlled oxidation of alcohols. This general strategy allows a series of crystalline CTFs with different monomers to be prepared, which are shown to have higher thermal stability and enhanced performance in photocatalysis as compared with the less crystalline or amorphous CTFs. This open-system approach is very simple and convenient, which presents a potential pathway to large-scale industrial production of crystalline CTFs.

Covalent triazine frameworks (CTFs) with aromatic triazine linkages have recently received increasing interest for various applications because of their rich nitrogen content and high chemical stability.O wing to the strong aromatic C=N bond and high chemical stability,o nly af ew CTFs are crystalline,a nd most CTFs are amorphous.H erein we report anew general strategy to give highly crystalline CTFs by in situ formation of aldehyde monomers through the controlled oxidation of alcohols.T his general strategy allows as eries of crystalline CTFs with different monomers to be prepared, which are shown to have higher thermal stability and enhanced performance in photocatalysis as compared with the less crystalline or amorphous CTFs.This open-system approach is very simple and convenient, which presents ap otential pathway to large-scale industrial production of crystalline CTFs.

Reactions of gold salts with various π-conjugated dialkynes have led to two homologous series of binuclear alkynylgold(I) complexes, linear rigid-rod Cy3PAu−C≡C−(CHCH) n −C≡C−AuPCy3 (n = 1−3, all-trans) (2a−c) and photochromic LAu−C≡C−DTE−C≡C−AuL (DTE = 1,2-di(2-methylthien-3-yl)cyclopentene or 1,2-di(2-methylthien-3-yl)-3,3,4,4,5,5-hexafluorocyclopentene) (L = PCy3, tricyclohexylphosphine or PPh3, triphenylphosphine) (4a−d). The photophysical properties of these complexes have been investigated. The emission spectra exhibited a progressive red-shift with increasing length of the bridge between the two Au(I) in the linear metal complexes 2. Photochromic alkynylgold(I) complexes 4 also exhibited fluorescence properties, and the emission wavelength was found to change upon variation of the dithienylethene (DTE) linkers as well as of the auxiliary phosphine ligands. It is revealed that the binuclear alkynylgold complexes with DTE units show photochromic behavior and that the efficiencies of the photochromic processes and conversions from the open- to the closed-ring isomers in the photostationary state (PSS) are greatly improved upon the introduction of gold. The photochromic process was also found to show complete reversibility, with restoration of the luminescence and NMR signals upon exposure to visible light.

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