Confinement has been shown to contribute to the dynamics of small molecules within nanoscale hydrophobic or hydrophilic cavities. Enclosure within a confined space can also influence energy transfer pathways, such as the enhancement of fluorescence over thermal relaxation. In this paper, the effect of confinement on the thermodynamic properties and reaction kinetics of small hydrophobic molecules confined in a soft polymeric template is detailed. A quasi-elastic neutron scattering experiment identified a substantial decrease in translational diffusion of pyrrole after solubilization within a hydrophobic cavity. This decrease in mobility is due to pyrrole’s closer packing and increased density under confinement vs the bulk liquid. The decreased mobility and increased density explain the spontaneous polymerization reaction of pyrrole observed within the cavity. The precise characterization of the polymerization kinetics under confinement found that the reaction is independent of pyrrole concentration, consistent with the close packing density. Kinetic data also show that confinement dimensionality finds a thermodynamic expression in the transition state entropy. The dynamics and kinetics experiments reported here offer rare empirical insight into the important influence that cavity geometry places on the reactions they host.
REFERENCES
1.
A. J.
Orr-Ewing
, “Taking the plunge: Chemical reaction dynamics in liquids
,” Chem. Soc. Rev.
46
, 7597
–7614
(2017
).2.
D.
Laage
, T.
Elsaesser
, and J. T.
Hynes
, “Water dynamics in the hydration shells of biomolecules
,” Chem. Rev.
117
, 10694
–10725
(2017
).3.
R.
Garcia-Meseguer
and B. K.
Carpenter
, “Re-evaluating the transition state for reactions in solution
,” Eur. J. Org. Chem.
2019
, 254
–266
.4.
S.
Essafi
and J. N.
Harvey
, “Rates of molecular vibrational energy transfer in organic solutions
,” J. Phys. Chem. A
122
, 3535
–3540
(2018
).5.
K.
Renggli
et al., “Selective and responsive nanoreactors
,” Adv. Funct. Mater.
21
, 1241
–1259
(2011
).6.
D.
Lensen
, D. M.
Vriezema
, and J. C. M.
van Hest
, “Polymeric microcapsules for synthetic applications
,” Macromol. Biosci.
8
, 991
–1005
(2008
).7.
A.
Dhakshinamoorthy
and H.
Garcia
, “Catalysis by metal nanoparticles embedded on metal–organic frameworks
,” Chem. Soc. Rev.
41
, 5262
(2012
).8.
H.
Cheng
et al., “Hierarchically self-assembled supramolecular host-guest delivery system for drug resistant cancer therapy
,” Biomacromolecules
19
, 1926
–1938
(2018
).9.
L.
Zhao
, J.
Cai
, Y.
Li
, J.
Wei
, and C.
Duan
, “A host–guest approach to combining enzymatic and artificial catalysis for catalyzing biomimetic monooxygenation
,” Nat. Commun.
11
, 2903
(2020
).10.
S.
Horike
, S.
Shimomura
, and S.
Kitagawa
, “Soft porous crystals
,” Nat. Chem.
1
, 695
–704
(2009
).11.
Y.
Fang
et al., “Catalytic reactions within the cavity of coordination cages
,” Chem. Soc. Rev.
48
, 4707
–4730
(2019
).12.
C.
Deraedt
and D.
Astruc
, “Supramolecular nanoreactors for catalysis
,” Coord. Chem. Rev.
324
, 106
–122
(2016
).13.
J.
Li
et al., “Capture of nitrogen dioxide and conversion to nitric acid in a porous metal–organic framework
,” Nat. Chem.
11
, 1085
–1090
(2019
).14.
X.
Li
and C.
Malardier-Jugroot
, “Synthesis of polypyrrole under confinement in aqueous environment
,” Mol. Simul.
37
, 694
–700
(2011
).15.
X.
Li
and C.
Malardier-Jugroot
, “Confinement effect in the synthesis of polypyrrole within polymeric templates in aqueous environments
,” Macromolecules
46
, 2258
–2266
(2013
).16.
M.
McTaggart
, M.
Jugroot
, and C.
Malardier-Jugroot
, “Biomimetic soft polymer nanomaterials for efficient chemical processes
,” in Green Processes for Nanotechnology: From Inorganic to Bioinspired Nanomaterials
(Springer
, 2015
).17.
H.
Zhao
and S. L.
Simon
, “Synthesis of polymers in nanoreactors: A tool for manipulating polymer properties
,” Polymer
211
, 123112
(2020
).18.
C.-G.
Wu
and T.
Bein
, “Conducting polyaniline filaments in a mesoporous channel host
,” Science
264
, 1757
–1759
(1994
).19.
M.
Tarnacka
et al., “Following kinetics and dynamics of DGEBA-aniline polymerization in nanoporous native alumina oxide membranes–FTIR and dielectric studies
,” Polymer
68
, 253
–261
(2015
).20.
B.
Sanz
, N.
Ballard
, Á.
Marcos-Fernández
, J. M.
Asua
, and C.
Mijangos
, “Confinement effects in the step-growth polymerization within AAO templates and modeling
,” Polymer
140
, 131
–139
(2018
).21.
J. M.
Giussi
, I.
Blaszczyk-Lezak
, M. S.
Cortizo
, and C.
Mijangos
, “In-situ polymerization of styrene in AAO nanocavities
,” Polymer
54
, 6886
–6893
(2013
).22.
T.
Uemura
, Y.
Kadowaki
, N.
Yanai
, and S.
Kitagawa
, “Template synthesis of porous polypyrrole in 3D coordination nanochannels
,” Chem. Mater.
21
, 4096
–4098
(2009
).23.
T.
Uemura
et al., “Conformation and molecular dynamics of single polystyrene chain confined in coordination nanospace
,” J. Am. Chem. Soc.
130
, 6781
–6788
(2008
).24.
T.
Uemura
, N.
Yanai
, and S.
Kitagawa
, “Polymerization reactions in porous coordination polymers
,” Chem. Soc. Rev.
38
, 1228
–1236
(2009
).25.
M.
Malvaldi
, S.
Bruzzone
, and F.
Picchioni
, “Confinement effect in diffusion-controlled stepwise polymerization by Monte Carlo simulation
,” J. Phys. Chem. B
110
, 12281
–12288
(2006
).26.
P. G.
de Gennes
, “Kinetics of diffusion-controlled processes in dense polymer systems. I. Nonentangled regimes
,” J. Chem. Phys.
76
, 3316
–3321
(1982
).27.
Y. P.
Koh
, Q.
Li
, and S. L.
Simon
, “Tg and reactivity at the nanoscale
,” Thermochim. Acta
492
, 45
–50
(2009
).28.
I.
Teraoka
, “Polymer solutions in confining geometries
,” Prog. Polym. Sci.
21
, 89
–149
(1996
).29.
M.
McTaggart
, C.
Malardier-Jugroot
, and M.
Jugroot
, “Self-assembled biomimetic nanoreactors I: Polymeric template
,” Chem. Phys. Lett.
636
, 216
–220
(2015
).30.
J.
Villa
et al., “How important are entropic contributions to enzyme catalysis?
,” Proc. Natl. Acad. Sci. U. S. A.
97
, 11899
–11904
(2000
).31.
L.
Xie
, M.
Yang
, and Z.-N.
Chen
, “Understanding the entropic effect in chorismate mutase reaction catalyzed by isochorismate-pyruvate lyase from: Pseudomonas aeruginosa (PchB)
,” Catal. Sci. Technol.
9
, 957
–965
(2019
).32.
J.
Åqvist
, M.
Kazemi
, G. V.
Isaksen
, and B. O.
Brandsdal
, “Entropy and enzyme catalysis
,” Acc. Chem. Res.
50
, 199
–207
(2017
).33.
J. P.
Richard
, “Protein flexibility and stiffness enable efficient enzymatic catalysis
,” J. Am. Chem. Soc.
141
, 3320
–3331
(2019
).34.
M.
McTaggart
, C.
Malardier-Jugroot
, and M.
Jugroot
, “Self-assembled biomimetic nanoreactors II: Noble metal active centers
,” Chem. Phys. Lett.
636
, 221
–227
(2015
).35.
M. N.
Groves
, C.
Malardier-jugroot
, and M.
Jugroot
, “Environmentally friendly synthesis of supportless Pt based nanoreactors in aqueous solution
,” Chem. Phys. Lett.
612
, 309
–312
(2014
).36.
37.
M.
Bée
, “La diffusion quasiélastique des neutrons; introduction et principes généraux
,” J. Phys. IV
10
, Pr1-1
(2000
).38.
U.
Balucani
and M.
Zoppi
, Dynamics of the liquid state
(Clarendon Press
, 1995
), Vol. 10.39.
Y.
Tan
and K.
Ghandi
, “Kinetics and mechanism of pyrrole chemical polymerization
,” Synth. Met.
175
, 183
–191
(2013
).2021
Crown
You do not currently have access to this content.
