Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, One Shields Ave., Davis, California 95616, USA.
Langmuir. 2013 Jun 25;29(25):8140-5. doi: 10.1021/la4012839. Epub 2013 Jun 13.
Metal-organic framework (MOF) porosity relies upon robust metal-organic bonds to retain structural rigidity upon solvent removal. Both the as-synthesized and activated Cu and Zn polymorphs of HKUST-1 were studied by room temperature acid solution calorimetry. Their enthalpies of formation from dense assemblages (metal oxide (ZnO or CuO), trimesic acid (TMA), and N,N-dimethylformamide (DMF)) were calculated from the calorimetric data. The enthalpy of formation (ΔHf) of the as-synthesized Cu-HKUST-H2O ([Cu3TMA2·3H2O]·5DMF) is -52.70 ± 0.34 kJ per mole of Cu. The ΔHf for Zn-HKUST-DMF ([Zn3TMA2·3DMF]·2DMF) is -54.22 ± 0.57 kJ per mole of Zn. The desolvated Cu-HKUST-dg [Cu3TMA2] has a ΔHf of 16.66 ± 0.51 kJ/mol per mole Cu. The ΔHf for Zn-HKUST-amorph [Zn3TMA2·2DMF] is -3.57 ± 0.21 kJ per mole of Zn. Solvent stabilizes the Cu-HKUST-H2O by -69.4 kJ per mole of Cu and Zn-HKUST-DMF by at least -50.7 kJ per mole of Zn. Such strong chemisorption of solvent is similar in magnitude to the strongly exothermic binding at low coverage for chemisorbed H2O on transition metal oxide nanoparticle surfaces. The strongly exothermic solvent-framework interaction suggests that solvent can play a critical role in obtaining a specific secondary building unit (SBU) topology.
金属-有机骨架（MOF）的孔隙率依赖于坚固的金属-有机键，以在去除溶剂后保持结构刚性。通过室温酸溶液量热法研究了 HKUST-1 的合成和激活的 Cu 和 Zn 多晶型物。从量热数据计算了它们从致密组装体（金属氧化物（ZnO 或 CuO）、均苯三甲酸（TMA）和 N，N-二甲基甲酰胺（DMF））形成的生成焓。合成的 Cu-HKUST-H2O([Cu3TMA2·3H2O]·5DMF)的生成焓（ΔHf）为每摩尔 Cu 为-52.70±0.34 kJ。Zn-HKUST-DMF([Zn3TMA2·3DMF]·2DMF)的ΔHf 为每摩尔 Zn 为-54.22±0.57 kJ。脱水的 Cu-HKUST-dg[Cu3TMA2]的ΔHf 为每摩尔 Cu 为 16.66±0.51 kJ/mol。Zn-HKUST-amorph[Zn3TMA2·2DMF]的ΔHf 为每摩尔 Zn 为-3.57±0.21 kJ。溶剂通过每摩尔 Cu 稳定 Cu-HKUST-H2O 达-69.4 kJ，通过每摩尔 Zn 稳定 Zn-HKUST-DMF 至少-50.7 kJ。溶剂的这种强化学吸附与过渡金属氧化物纳米颗粒表面上化学吸附的 H2O 在低覆盖率下强烈放热结合的程度相似。强放热的溶剂-骨架相互作用表明溶剂可以在获得特定的二级结构单元（SBU）拓扑结构中发挥关键作用。
