Inspired by earlier work, 58 spectral simulations were then performed to enable a more quantitative analysis (Figure ). The only free parameters in the simulations are D// and D ⊥ . The simulations shown in Figure suggested that CO2 diffusion along the framework pores takes a value of D// = D// = 1.5(4) × 10 -9 m 2 s -1 . This value is comparable to liquid water diffusion at ambient conditions, and is 4 orders of magnitude slower than the diffusion of free CO2 gas. For diffusion of CO2 between the MOF pores, we were only able to conclude an upper limit of D ⊥ < 10 -13 m 2 s -1 , and it was not possible to conclude whether or not D ⊥ had non-zero value. These findings show that the CO2 diffusion between the MOF channels is at least 10,000 times slower than diffusion along the MOF channels, i.e. the diffusion is very strongly anisotropic. This finding has implications for the practical applications of these materials, and suggests that rod-like crystals are in-fact not desired for practical applications due to their long diffusion pathways, and the possibility of poor blockage leading to inaccessible regions of the material.