Mesostructured silica studied by silicon filtered reverse cross-polarization solid state NMR

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Mesostructured silica studied by silicon filtered reverse cross-polarization solid state NMR

Guillaume Laurent, Niki Baccile, Jocelyne Maquet, Christian Bonhomme, Florence Babonneau

To cite this version:

Guillaume Laurent, Niki Baccile, Jocelyne Maquet, Christian Bonhomme, Florence Babonneau. Mesostructured silica studied by silicon filtered reverse cross-polarization solid state NMR. Interna-tional school on high-field NMR spectroscopy for solids and liquids, May 2006, Les Houches, France. �hal-01881960�

1_H 29_Si 1_H 29_Si 1_H 29_Si N(CH₃)₃ (CH₂)_n

Small and large OH signal

x16 x16

- Signal from polar

head at low t_CP2

- Strong OH signal

N(CH₃)₃

(CH₂)_n

Mesostructured silica studied

by silicon filtered reverse cross-polarization solid state NMR

Nano-organised silica powders, prepared from self-assembly of surfactants and siliceous species, have done their breakthrough in the early ‘90s and, ever since, the interest of the material’s community is growing continuously because of the extreme versatility of the process and the important number of possible applications achievable. Despite numerous contributions to the subject, some basic information concerning interactions at organic/inorganic interface has not been clarified yet. This poster will try to show how some advanced solid state NMR experiences can contribute to give more insights to some structural problems at the silica/surfactant interface and host-guest interactions between silica and embedded molecules.

Introduction

Me so structure d Silica: Beck e t A l., Nature 19 92 Surfactant aqueous solution Si(OEt)₄ precursor (t = 0) t = 2 min t = 3 hrs SiO₂ SiO₂ SiO₂ SiO₂ Calcination

CTA

+

– SiO

₂

interactions

SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 a = 44 Å a b SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 a = 44 Å 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 a = 44 Å a b a b SiO₂ X -Si-OH Si-OH Si-OH SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 a = 44 Å a b SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 a = 44 Å 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 0 _{2 3 4 5 6} d10 In te nsity 2 d11 d20 a = 44 Å a b a b SiO₂ X -Si-OH Si-OH Si-OH SiO2 SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ a = 44 Å a b SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ a = 44 Å 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ a = 44 Å a b a b Si-O -Si-O -Si-O -+ SiO₂ SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ a = 44 Å a b SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH3 CH3 N+ CTAB Br- CH3 CH3 CH3 N+ 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ a = 44 Å 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ 0 _{2 3 4 5 6} d10 Int ensity 2 d11 d₂₀ a = 44 Å a b a b Si-O -Si-O -Si-O -+ Reverse CP-MAS 1_H-29_Si-1_H B₀= 7.04 T; MAS= 14 kHz

CTA

+

is further away from surface in acid-based materials

Direct and counter-ion mediated interaction

Guillaume LAURENT, Niki BACCILE, Jocelyne MAQUET, Christian BONHOMME and Florence BABONNEAU

Laboratoire de Chimie de la Matière Condensée de Paris, CNRS-UMR-7574, Université Pierre et Marie Curie, Paris

Acid catalyzed material Basic catalyzed material

-No silanol signal - CTAB signal stronger than

silanol SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH₃ CH₃ N+ 0 _{2 3 4 5 6} d₁₀ In ten sit y 2 d_{11 d20} a = 44 Å a b SBA-3 phase 2D-hexagonal (p6m) Acidic conditions CTAB Br- CH3 CH₃ CH₃ N+ CTAB Br- CH3 CH₃ CH₃ N+ 0 _{2 3 4 5 6} d₁₀ In ten sit y 2 d_{11 d20} a = 44 Å 0 _{2 3 4 5 6} d₁₀ In ten sit y 2 d_{11 d20} 0 _{2 3 4 5 6} d₁₀ In ten sit y 2 d_{11 d20} a = 44 Å a b a b +

SiO

₂

+ + -X -1_{H single pulse} t_cp1=3ms t_cp2 variable ns=1104 Reverse hetcor 1_H-29_Si-1_H dec. 1_H 29_Si Contact time CP Acquisition t₁ t₂ dec. 1_H 29_Si Contact time CP Acquisition dec. 1_H 29_Si Contact time CP Acquisition t₁ t₂ t_CP Normal hetcor 1_H-29_Si Normal hetcor Reverse hetcor

•Signal enhancement

•Resolution enhancement

2D heteronuclear correlation

SiO

₂

Benzoic Acid impregnation

ns=800, td₁=64, si₁=256, t_cp=3ms, B₀=9.4T ns=800, td₁=59, si₁=256, t_cp1=t_cp2=3ms, B₀=9.4T

2D silicon filtered noesy

1_H 1_H t_m=10ms ns=180 x2 1_H 1_H t_m=140µs ns=360 1_H 1_H t_m=1ms ns=360 td₁=128, si₁=256, t_cp1=3ms, t_cp2=5ms, B₀=7.04T

•Probing only

1

_{H close to}

silica

First row

t_m=140µs

t_m=1ms

t_m=10ms

- peaks on one side of the