MOF Open Metal Site Catalysis

Substrate Feed

Substrate concentration 18

Diffusion rate (pore mobility) 1.0×

Active Site

Lewis-acid capture radius 0.55

Catalytic rate k_cat (s⁻¹) 2.0

Active Site State

OPEN — awaiting substrate

Live Readouts

Turnovers (this site)

TOF (site⁻¹ min⁻¹)

0.0

Residence time (bound)

—

Free substrates

How it works

Many metal-organic frameworks (e.g. MOF-74, UiO-66-based catalysts) expose a coordinatively unsaturated open metal site once solvent ligands are removed by activation. That exposed metal ion acts as a Lewis acid: it can bind an incoming substrate molecule, polarize/activate it, and release a transformed product — the same open-slot chemistry behind heterogeneous single-site catalysis.

This simulation treats each substrate as a particle undergoing Brownian diffusion inside the pore. When one enters the capture radius of an unoccupied site, it binds with a probability set by a first-order rate law; while bound, it converts to product on a stochastic clock set by k_cat:

P(bind in Δt)   = 1 − exp(−k_on · Δt)
P(react in Δt)  = 1 − exp(−k_cat · Δt)
TOF = turnovers / (active sites · time)

This is the discrete, single-molecule analogue of Michaelis–Menten kinetics: at low substrate concentration, turnover is limited by how often a molecule diffuses into capture range (diffusion-limited); at high concentration and low k_cat, it is limited by the chemical step itself (reaction-limited). Turnover frequency (TOF) — product molecules released per active site per unit time — is the standard metric used to compare real MOF catalysts.

Substrate concentration — number of molecules diffusing in the pore volume; more molecules raise collision frequency with the site.
Diffusion rate — how fast substrates random-walk through the pore (proxy for temperature / pore confinement).
Capture radius — the effective reach of the open metal site's Lewis-acid field (site accessibility / steric openness).
k_cat — the intrinsic chemical turnover rate of the bound intermediate once captured.

Substrate (unreacted) Product (released) Open metal site

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.