Metal‐ion‐dependent, Solvent‐mediated Structural Transformation and Simultaneous Partial Transmetalation of an srs Framework into Desulfurization‐efficient Co‐Cu‐HKUST‐1

[Co2(BTC)(Cl)(DMA)3] (1) (BTC3– = benzene‐1,3,5‐tricarboxylate, DMA = N,N‐dimethylacetamide) obtained from the reaction between Co2+ and H3BTC in DMA features a three‐dimensional srs framework built of 3‐connected {Co2(COO)3} as secondary building units and BTC3– as spacers. When exposed to DMA solution of Cu(NO3)2, 1 was progressively transformed into the first heterometallic Co‐Cu‐HKUST‐1 ([Co0.14Cu2.86(BTC)2]) (2) of such kind via unusually solvent‐mediated structural transformation and simultaneous partial transmetalation. While the mechanism for such conversion is proposed based on systematic studies, 2 was revealed to be an equally efficient desulfurization adsorbent as the homometallic Cu‐HKUST‐1 in removing thiophene (0.142 mmol S per gram of adsorbent). However, when exposed to Zn(NO3)2 solution in DMA for longer time, 1 retained its framework with limited metal‐ion exchange, resulting in the formation of [Co1.93Zn0.07(BTC)(Cl)(DMA)3] (3). Possible reasons responsible for the formation of 2 and 3 through different routes could be due to the less solubility and more thermodynamic stability of 2 in comparison with those of 1, and the different coordination geometries which Co2+, Zn2+ and Cu2+ prefer.