For comparison, bulk CoMo6Sx was prepared under similar conditions but with higher reaction temperature using bare CoMo6O24 without NU1K (Figure ). Also prepared for comparison were Mo7O24@NU1K and MoSx@NU1K; see Supplementary Information. 17 Characterization. CoMo6O24@NU1K and CoMo6S24@NU1K unit cells, as seen by the Bragg peak positions on powder Xray diffraction (Figure ), resemble that of NU1K, except for a decrease in the intensity of diffraction peaks at 2θ=7.44° corresponding to a decrease in the coherency of planes with a spacing of 1.0 nm (highlighted in yellow in Figure ). The diffraction pattern matches well with a predicted/simulated pattern where the POM is located between two nodes in inter-channel windows (c-pores). BET surface areas calculated from N2 isotherms of CoMo6O24@NU1K (1588 m 2 /g) and CoMo6S24@NU1K (1160 m 2 /g) are significantly smaller than that of bare NU1K (2236 m 2 /g; Figure ). In part, the decreases reflect increases in sample mass. The cluster@NU1K isotherms show a type IV feature, similar to that of NU1K, which is associated with the filling of mesopores. Isotherm-derived pore size distributions (PSDs) indicate for both samples contraction of mesopore and micropore widths (Figure ) -a phenomenon that has been associated elsewhere with displacement or elimination of node-ligated formate ions when followed by thermal activation. More striking are the large decreases in the volume of the triangular micropores, an indication that the c-pore-sited clusters extend into the triangular channels/pores. The decrease with CoMo6S24@NU1K is greater than with CoMo6O24@NU1K, of S relative to O.