2. Materials and experiments
2.1. Materials
chromium (III) nitrate nonahydrate
(Cr(NO3)3ยท9H2O) and
1,4-ben-zenedicarboxylic acid (H2BDC) were obtained from
J&K (China). N-methylimidazolium and chlorobutanol were purchased from
Shanghai Bide Pharmatech Ltd. N,N -dimethylforma-mide (DMF),
methanol and ethyl acetate were obtained from Beijing Chemical Works.
All chemicals were utilized directly from commercial purchases and
without additional purification.