Pore diameter dependence of catalytic activity: p-nitrobenzaldehyde conversion to an aldol product in amine-functionalized mesoporous silica.

The reaction yield for conversion of p-nitrobenzaldehyde (PNB) to an aldol product in amine-functionalized mesoporous silica nanoparticles (MSN) exhibits a 20-fold enhancement for a modest increase in pore diameter, d. This enhanced catalytic activity is shown to reflect a strong increase in the "passing propensity," P, of reactant and product species inside the pores. We find that P ≈ 0, corresponding to single-file diffusion, applies for the smallest d which still significantly exceeds the linear dimensions of PNB and the aldol product. However, in this regime of narrow pores, these elongated species must align with each other and with the pore axis in order to pass. Thus, P reflects both translational and rotational diffusion. Langevin simulation accounting for these features is used to determine P versus d. The results are also augmented by analytic theory for small and large d where simulation is inefficient. The connection with the catalytic activity and yield is achieved by the incorporation of results for P into a multi-scale modeling framework. Specifically, we apply a spatially coarse-grained (CG) stochastic model for the overall catalytic reaction-diffusion process in MSN. Pores are treated as linear arrays of cells from the ends of which species adsorb and desorb, and between which species hop and exchange, with the exchange rate reflecting P. CG model predictions including yield are assessed by Kinetic Monte Carlo simulation.

[1]  Harry A. Stern,et al.  Bridging the gap between long time trajectories and reaction pathways , 2003 .

[2]  Christopher W. Jones,et al.  Tuning cooperativity by controlling the linker length of silica-supported amines in catalysis and CO2 capture. , 2012, Journal of the American Chemical Society.

[3]  G. Marin,et al.  Effects of amine structure and base strength on acid-base cooperative aldol condensation , 2015 .

[4]  Christopher W. Jones,et al.  Cooperative Catalysis with Acid–Base Bifunctional Mesoporous Silica: Impact of Grafting and Co-condensation Synthesis Methods on Material Structure and Catalytic Properties , 2012 .

[5]  V. S. Lin,et al.  Cooperative catalysis by general acid and base bifunctionalized mesoporous silica nanospheres. , 2005, Angewandte Chemie.

[6]  V. S. Lin,et al.  Interplay between Anomalous Transport and Catalytic Reaction Kinetics in Single-File Nanoporous Systems , 2011 .

[7]  T. E. Harris.  Diffusion with “collisions” between particles , 1965, Journal of Applied Probability.

[8]  V. S. Lin,et al.  Controlling reactivity of nanoporous catalyst materials by tuning reaction product-pore interior interactions: statistical mechanical modeling. , 2013, The Journal of chemical physics.

[9]  Aleksandar Donev,et al.  Brownian dynamics of confined rigid bodies. , 2015, The Journal of chemical physics.

[10]  F. Perrin,et al.  Mouvement brownien d'un ellipsoide - I. Dispersion diélectrique pour des molécules ellipsoidales , 1934 .

[11]  Toshinori Mori,et al.  Neutron Scattering Study on Dynamics of Water Molecules in MCM-41 , 1999 .

[12]  Q. Wei,et al.  Brownian motion of arbitrarily shaped particles in two dimensions. , 2014, Langmuir : the ACS journal of surfaces and colloids.

[13]  Christopher W. Jones,et al.  Kinetic and Mechanistic Examination of Acid–Base Bifunctional Aminosilica Catalysts in Aldol and Nitroaldol Condensations , 2016 .

[14]  A. Schreiber,et al.  Freezing and melting of water confined in silica nanopores. , 2008, Chemphyschem : a European journal of chemical physics and physical chemistry.

[15]  D. Sholl,et al.  Normal, single-file, and dual-mode diffusion of binary adsorbate mixtures in AlPO4-5 , 1997 .

[16]  J. Michaelis,et al.  Tuning single-molecule dynamics in functionalized mesoporous silica. , 2009, Chemistry.

[17]  Andrés J. García,et al.  Boundary Conditions for Diffusion-Mediated Processes within Linear Nanopores: Exact Treatment of Coupling to an Equilibrated External Fluid , 2017 .

[18]  D. Fushman,et al.  An efficient computational method for predicting rotational diffusion tensors of globular proteins using an ellipsoid representation. , 2006, Journal of the American Chemical Society.

[19]  Takeshi Kobayashi,et al.  Substrate inhibition in the heterogeneous catalyzed aldol condensation: A mechanistic study of supported organocatalysts , 2012 .

[20]  Hahn,et al.  Single-file diffusion observation. , 1996, Physical review letters.

[21]  F. Jiao,et al.  Nanostructured cobalt oxide clusters in mesoporous silica as efficient oxygen-evolving catalysts. , 2009, Angewandte Chemie.

[22]  C. Steefel,et al.  Molecular dynamics simulations of water structure and diffusion in silica nanopores , 2012 .

[23]  W. Sachtler,et al.  Neopentane Conversion Catalyzed by Pd in L-Zeolite: Effects of Protons, Ions, and Zeolite Structure , 1993 .

[24]  R. Dowben,et al.  A general ellipsoid cannot always serve as a model for the rotational diffusion properties of arbitrarily shaped rigid molecules. , 1979, Proceedings of the National Academy of Sciences of the United States of America.

[25]  James W. Evans,et al.  Kinetic Monte Carlo Simulation of Statistical Mechanical Models and Coarse-Grained Mesoscale Descriptions of Catalytic Reaction-Diffusion Processes: 1D Nanoporous and 2D Surface Systems. , 2015, Chemical reviews.

[26]  David Chandler,et al.  Transition path sampling: throwing ropes over rough mountain passes, in the dark. , 2002, Annual review of physical chemistry.

[27]  Victor S-Y Lin,et al.  Mesoporous silica nanoparticles for intracellular delivery of membrane-impermeable proteins. , 2007, Journal of the American Chemical Society.

[28]  D. Sholl.  Characterizing adsorbate passage in molecular sieve pores , 1999 .

[29]  Generalized hydrodynamic treatment of the interplay between restricted transport and catalytic reactions in nanoporous materials. , 2012, Physical review letters.

[30]  F. Perrin,et al.  Mouvement Brownien d'un ellipsoide (II). Rotation libre et dépolarisation des fluorescences. Translation et diffusion de molécules ellipsoidales , 1936 .

[31]  C. Rödenbeck,et al.  Tracer Exchange and Catalytic Reaction in Single-File Systems , 1995 .

[32]  John Waldron,et al.  The Langevin Equation , 2004 .

[33]  Sidney Redner,et al.  A guide to first-passage processes , 2001 .

[34]  Mark S Gordon,et al.  Silanol-Assisted Carbinolamine Formation in an Amine-Functionalized Mesoporous Silica Surface: Theoretical Investigation by Fragmentation Methods. , 2016, The journal of physical chemistry. B.

[35]  J. García de la Torre,et al.  Hydrodynamic properties of rigid particles: comparison of different modeling and computational procedures. , 1999, Biophysical journal.

[36]  F. Rey,et al.  Heterogeneous catalysts obtained by grafting metallocene complexes onto mesoporous silica , 1995, Nature.

[37]  James Wei,et al.  Diffusion and reaction in high-occupancy zeolite catalysts—I. A stochastic theory , 1991 .

[38]  K. Wynne,et al.  Stokes-Einstein-Debye failure in molecular orientational diffusion: exception or rule? , 2014, The journal of physical chemistry. B.

[39]  M. Mavrovouniotis,et al.  A CONSISTENT CORRELATION APPROACH TO SINGLE FILE DIFFUSION WITH REACTION , 1999 .

[40]  V. Bloomfield,et al.  Hydrodynamic properties of macromolecular complexes. I. Translation , 1977 .

[41]  I. Slowing,et al.  Langevin and fOkker-Planck analyses of inhibited molecular passing processes controlling transport and reactivity in nanoporous materials. , 2014, Physical review letters.

[42]  J. B. Higgins,et al.  A new family of mesoporous molecular sieves prepared with liquid crystal templates , 1992 .

[43]  Christopher W. Jones,et al.  Molecular Dynamics Simulations of Aldol Condensation Catalyzed by Alkylamine-Functionalized Crystalline Silica Surfaces. , 2016, Journal of the American Chemical Society.

[44]  K. Herwig,et al.  Observation of fractional Stokes-Einstein behavior in the simplest hydrogen-bonded liquid. , 2007, Physical review letters.

[45]  W. Briels,et al.  An elementary singularity-free Rotational Brownian Dynamics algorithm for anisotropic particles. , 2015, The Journal of chemical physics.

[46]  S. Prager,et al.  Variational Treatment of Hydrodynamic Interaction in Polymers , 1969 .

[47]  Kai Sun,et al.  Brownian motion of boomerang colloidal particles. , 2013, Physical review letters.

[48]  S. Anthony,et al.  Translation-rotation decoupling of colloidal clusters of various symmetries. , 2008, The Journal of chemical physics.