Multi Variant Surface Mounted Metal-Organic Frameworks

Hybrid surface mounted metal-organic frameworks (h-SURMOFs) of multi variant core-shell (cs) and core-shell-shell (css) structures (SURMOF A-B and A-B-C, A: [Cu-2(bdc)(2)(dabco)]; B: [Cu-2(NH2-bdc)(2)(dabco)]; C: [Cu-2(ndc)(2)(dabco)], bdc = 1,4-benzenedicarboxylate; NH2-bdc = 2-amino-1,4-benzenedicarboxylate; ndc = 1,4-naphtalenedicarboxylate; dabco = 1,4-diazabicyclo[2.2.2]octane) with specific crystallographic [001] orientation and incorporated amino groups at a controllable depth within the bulk are deposited via liquid phase epitaxial (LPE) approach on pyridyl-terminated self-assembled monolayers (SAM). The location of the (amino) functionality can be precisely controlled through tuning the thickness (number of deposition cycles) of each sub-multilayer block according to the LPE deposition protocol. The chemo-selective and location-specific post deposition (chemical) modification of the amino groups in the cs and css-type h-SURMOF samples is achieved. The h-SURMOFs allow one to probe functional groups at certain location in the volume of hybrid MOF crystallites attached to surfaces as thin film coatings. Multiplex adsorption kinetics of FPI (FPI = 4-fluorophenyl isothiocyanate) is observed in h-SURMOFs due to their multi-variant pore structures in samples of A-B and A-B-C. Conceptually, the stepwise LPE growth method enables fabrication of hybrid SURMOFs and incorporation of multi-variant functionalities into one homogeneous thin film material, providing precisely tunable pore environment for selective adsorption, separation, etc.