Impact of Synthesis Parameters on the Formation of Defects in HKUST-1

By employing various synthetic conditions, such as Cu(NO3)(2).3H(2)O and Cu(BF4)(2).6H(2)O as copper ion sources and different solvents, defect-engineered analogues of metalorganic framework (MOF) [Cu-3(BTC)(2)] (HKUST-1; BTC = 1,3,5-benzenetricarboxylate) with isophthalate (IP) incorporation (DEMOFs) were synthesised and characterised by powder XRD, SEM, IR spectroscopy, thermogravimetric analysis, NMR spectroscopy and N-2 sorption. The results show that the choice of counter ions impacts the properties of the samples especially at high concentrations of IP. The combination of DMF and Cu(BF4) (2).6H(2)O turns out to be superior for DEMOFs with IP incorporation up to 25 %. Ultrahigh-vacuum IR spectra recorded upon CO adsorption together with the results of X-ray photoelectron spectroscopic studies show the generation of coordinatively unsaturated Cu+ sites. The results suggest the presence of two different defect types, that is, missing-linker defects and missing paddlewheels for high concentrations of IP.