2.1 | Materials
Chemical reagents were commercially available and used without further
purification.
Co(NO3)2ยท6H2O (98%) was
obtained from Sigma-Aldrich. Pyrazine (99%) and
2,5-dihydroxyterephthalic acid (97%) were provided by Shanghai Aladdin
Bio-Chem Technology Co., LTD. N, N-dimethylformamide (DMF, AR), ethanol
(AR) and methanol (AR) were obtained from Sinopharm Group Co., LTD.