Synthesis and structural characterization of three copper coordination polymers with pyridine derivatives from hydro(solvo)thermal in situ decarboxylation reactions of 2,5-dicarboxylpyridine

The hydro(solvo)thermal self-assembles of CuI, KI and 2,5-dicarboxylpyridine [2,5-(COOH)2py] in different molar ratios in H2O/alcohol solutions produced three Cu coordination polymers as 2-D [N-C2H5py][Cu3I4] 1, 1-D [N-CH3py][Cu2I3] 2 as well as 1-D [Cu(2-COOpy)2]H2O 3 (N-C2H5py=N-ethylpyridine, N-CH3py=N-methylpyridine, 2-COOpy=2-carboxylpyridine). N-C2H5py in 1 and N-CH3py in 2 derived from the solvothermal in situ simultaneous decarboxylation and N-alkylation reactions of 2,5-(COOH)2py. The semi-decarboxylation reaction of 2,5-(COOH)2py into 2-COOpy occurred in the preparation of 3. X-ray single-crystal analysis revealed that CuI is transformed into a 2-D [Cu3I4]− layer in compound 1 and a 1-D chain in compound 2, templated by [N-C2H5py]+ and [N-CH3py]+, respectively. Compound 3 is a divalent Cu compound. The Cu(II) centers with a 4+2 geometry are coordinated by μ3-mode 2-COOpy ligands. All of the title compounds were characterized by CHN analysis, IR spectrum analysis and TG analysis. Compounds 1 and 2 exhibit fluorescence properties with the maximum emissions at 581 nm for 1 and 537 nm for 2.

Graphical abstractThree compounds were obtained via in situ metal–ligand hydro(solvo)thermal reactions of 2,5-(cooh)2py with cui. Three types of in situ reactions occurred for 2,5-(cooh)2py: decarboxylation n-ethylated in 1, n-methylated in 2 and semi-decarboxylation in 3.Figure optionsDownload full-size imageDownload as PowerPoint slide