Supporting Information

Structure-Directing Agent Governs theLocation of Silanol Defects in Zeolites.

Eddy Dib,∗ Julien Grand, Svetlana Mintova, and Christian Fernandez∗

Laboratoire Catalyse et Spectrochimie, ENSICAEN, Université de Caen, CNRS, 6 Bd. duMaréchal Juin, 14050 Caen, France

E-mail: eddy.dib@ensicaen.fr; christian.fernandez@ensicaen.fr

Synthesis

Materials

Tetra-n-propyl-ammonium hydroxide (TPAOH,20 wt. % in water solution, Alfa Aesar) andtetra-ethyl orthosilicate (TEOS, 98%, Aldrich)were used without further purification. Doublydeionized water was used throughout the syn-thesis and post-synthesis treatments. Syntheseswere carried out in 100 cm3 polypropylene bot-tle (PP bottle) at autogenous pressure withoutagitation.

Pure silica MFI-type zeolites

The following molar composition of the precur-sor suspension was used for the synthesis of MFIzeolites: 1.0 SiO2 : 0.12 (TPA)2O : 20 H2O. Ina typical synthesis, 5.0 g of TEOS was added to5.85 g of TPAOH and 3.95 g of water with stir-ring at room temperature (pH =12). The ob-tained water-clear suspension was stirred for 3h at room temperature and further hydrolyzedfor 4 h on an orbital shaker. The final suspen-sion was subjected to hydrothermal treatmentat 363 K for 8 h. After crystallization, the sus-pension was purified and the nanometer-sized

∗To whom correspondence should be addressed

crystals were purified by high-speed centrifuga-tion (20000 rpm, 20 min). The obtained solidproduct was washed with hot doubly deion-ized water (heated at 343 K for 30 min) tillthe pH reaches 7.5. The nanometer-sized crys-tals were subjected to freeze drying in order toprevent irreversible agglomeration. The freeze-dried samples were calcined at 823 K (heatingrate 2 K/min) in air for 6 h.

CharacterizationThe crystallinity of the as-synthesized zeoliteswas characterized thoroughly by XRD and mi-croscopic measurements.

Figure S1: Powder XRD pattern of pure-silicaMFI-type zeolites as-synthesized.

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X-ray diffraction

The high crystallinity of the MFI-typenanometer-sized zeolites were revealed by pow-der X-ray diffraction (XRD) patterns, obtainedwith a PANalytical XPert Pro diffractometerusing Cu Kα radiation (λ = 1.5418 Å, 45 kV,40 mA) (figure S1).

Figure S2: (a) SEM and (b) TEM pictures pure-silica MFI-type zeolites as-synthesized.

Electron microscopy

The crystal size and homogeneity of the samplewere determined by scanning electron micro-scope (SEM) using a MIRA-LMH (TESCAN)equipped with a field emission gun using an ac-celerating voltage of 30.0 kV. More informationwere provided by high-resolution transmissionelectron microscopy (HRTEM), using a JEOLModel 2010 FEG system operating at 200 kV(figure S2).

Figure S3: TGA analysis of pure-silica MFI-typezeolites as-synthesized.

Thermal analysis

The thermo-gravimetric analysis (TGA/DTA)measurements were carried out on a SETSYS1750 CS evolution instrument (SETARAM).The sample was heated from 298 to 1173 Kwith a heating ramp of 5 K/min (flow rate: 40mL/min) (figure S3).

Nuclear magnetic resonance13C{1H} cross polarization (CP) and conven-tional 29Si magic-angle spinning (MAS) NMRspectra were acquired respectively at 125.7 and99.3 MHz on a Bruker Avance III-HD 500 (11.7T), using 4.0-mm outer diameter probe. Ra-diofrequency powers of 125 and 50 kHz and re-cycle delays of 2 and 30 s were used respectively.1H decoupling of 60 kHz were used during theacquisition and a contact time of 5 ms was usedin the case of 13C{1H} NMR. (see figure S4).

Figure S4: (a) 13C{1H} CP and (b) 29Si MASNMR spectra of pure-silica MFI-type zeolites as-synthesized.

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Two-dimensional DQ androtor-encoded DQ (BaBa)experimentsProton is by far the most abundant and sen-sitive nucleus in NMR. It is obviously an ad-vantage when there is a low concentration ofprotons in the sample. However, it can alsobe a drawback in the reverse case, when theconcentration of protons is high, because of theoccurrence of strong dipolar couplings directlyrelated to the internuclear distance, which pre-vent to obtain well-resolved spectra.To overcome this problem, magic angle spin-

ning (MAS) technique and several homonucleardecoupling sequences have been developed inthe last decades, which make possible to recordliquid-like 1H NMR spectra for solid samples.1,2

However, enhancing the resolution of the1H NMR spectra lead invariably to a lossof precious structural and dynamical informa-tion. Thus, the so-called recoupling techniquesaiming to reintroduce the anisotropic interac-tions has been developed.3,4 Among the mostvaluable recoupling techniques, the double-quantum/single-quantum (DQ-SQ) correlationmethods are used to restore the through-spacedipole-dipole coupling while preserving the highspectral resolution provided by fast MAS spin-ning.Spiess and co-workers developed an original

approach to measure the internuclear distancebetween protons in several organic systems inthe presence of multi-core interactions by usingrotor-encoded DQ experiments.5,6 The spinningsideband patterns that appear in the indirectdimension of such experiments are directly re-flecting the dipolar couplings, which can be ex-tracted by simulation. Using this method, the1H-1H distances can be determined.7Conventional proton (1H) magic-angle spin-

ning (MAS) and two-dimensional 1H-1Hdouble-quantum (DQ) NMR spectra were ac-quired at 500 MHz using 1.9-mm outer diameterzirconia rotors spun at 40 kHz, a radiofrequencypower of 100 kHz and a recycle delay of 2 s.The recoupling of the DQ coherence was per-

formed following the well-known BaBa pulse se-

τR2

τR2

τR2

τR2

L

X XY YX XY Y

I

I I’t1 t2

Excitation Conversion

Figure S5: Scheme of the DQ-SQ correlation NMRpulse sequence (BaBa) used in this work. The block(I) consist in a series of 90◦ pulses separated byhalf rotor period delays. In this block the pulsesare phase-cycled as indicated. A first block (pos-sibly repeated L times) is used for the creation ofdouble quantum coherence and a second one (I’)for the conversion of the DQ coherence to observ-able single-quantum signal. For the conventionalrotor-synchronized DQ spectra, the delay t1 is in-cremented by an integer multiple of the rotor pe-riod. For the rotor-encoded DQ experiment whichproduce sidebands in the indirect dimension, thedelay is incremented by a small fraction of the ro-tor period (typically 1/10 which then produce 10spinning sidebands)

Figure S6: Rotor-encoded DQ 1H NMR spectrumof the as-synthesized TPA-silicalite-1. The experi-ment is performed in non synchronized rotor con-ditions.

quence.8 The incremented delay in the indirectdimension (δt1) is equal to 50 µs (i.e., two times

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Figure S7: A) Spinning sideband pattern (ssb)for the proton resonance at 10.2 ppm. top spec-trum: experimental spinning sideband pattern;model a) best modeled spectrum; model b-c) modelspectra to show the sensitivity of simulation toa change of the 1H. . . 1H distances as indicated.B) Map of the normalized squared residuals be-tween experimental (ye) and modeled (ym) spec-tra: S =

∑i (yei − ymi)

2/∑

i yei2 as a function

of the OH. . .OH and CH3. . . OH distances (an ar-ray of 40 by 40 spectra is used to draw the map).Labels (a) to (d) show the location of the modelspectra in A

the rotor spinning period) (see figure S5).The rotor-encoded BaBa experiment was

recorded using t1 increment much smaller thana rotor period gives rise to a spinning sideband

(ssb) pattern in the DQ dimension, which hasbeen shown to be only due to the presence ofthe homonuclear dipolar coupling interactions(see figure S6).An accurate determination of the dipole-

dipole distance is then straightforward from thesimulation of this ssb pattern in Figure S7.

Simpson simulations

The simulation of rotor-encoded 1H–1H DQspinning-sideband experiments was done usingthe freely available Simpson software.9 A typi-cal TCL script used for the Simpson simulationof such experiments is given in the followinglisting, adapted from a similar script publishedin ref (10). Due to the rapidly prohibitive lengthof such computation we have limited the inter-action to 5 spins (2 protons in two different OHgroups and 3 protons in a methyl.The results of the Simpson simulations are

reported in fig. S7.

Triple-quantum experiments

As shown above, the spinning sideband pat-terns obtained in the rotor encoded 1Hdouble-quantum NMR experiment of theTPA-silicalite-1 show a doublet for both theCH3. . . HO and OH. . . HO correlation peaks(figure S6). No triplet of spinning sidebandsis observed in the DQ dimension, converselyto the case of ZSM-12 reported by Shantz etal.11 where three silanols are in close vicinity.However, the diagonal peak observed at 10.2ppm in the BaBa (DQ) experiment (see figure1 in the main manuscript) for the OH groupsproves that they are not isolated. Therefore,we assume as stated in the main manuscriptthat these protons are mainly arranged bypairs in the MFI channels. In order to con-firm this hypothesis, it seems interesting toperform triple-quantum (TQ) filtered experi-ments which can exhibit diagonal and cross-peaks only if at least 3 protons are coupled. Asshown by Eden and Brinkmann,12,13 MQ phase-cycled symmetry-based pulse sequence such as[S0S

′0]3

1 with S0 = RN νn and S ′0 = RN−νn are

among the most efficient methods to create TQ

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Figure S8: TQ-SQ correlation spectrumrecorded using the R421 symmetry based pulsesequence. Only correlations between the propylprotons can be detected.

coherences. Due to the strong spin diffusionin proton spin systems, it is important to usethe shortest excitation and reconversion blockduration for such experiments. Therefore wechoose the R421 sequence, which make the over-all excitation (and conversion) duration equalto 6 rotor periods, i.e., 150µs.Figure S8 displays the TQ-SQ correlation

spectrum of the TPA-MFI zeolite. It showsmainly a diagonal correlation peak between themethyl protons (Hγ). Additionally off-diagonalpeaks appear between the propyl protons. Asexpected no correlation peak appears betweenthe silanols (δ = 10.2 ppm δTQ = 30.6 ppm), showing that there are not forming tripletsas in the ZSM-12. Note however that whenthe excitation time is increased, correlations be-tween the silanols at 10.2 ppm begin to be de-tected. However new correlation peaks are alsodetected between the silanols and all protonsof the propyl chain. The latter shows that thecorrelation peaks in this case are mainly due tothe proton spin diffusion and therefore can notbe interpreted in terms of local proximities.

Simpson script for computing rotor-encoded DQ experiments

spinsys {

# define the observation channel andnuclei systemchannels 1Hnuclei 1H 1H 1H 1H 1H

# OH chemical shiftsshift 1 10.20p 0 0 0 0 0shift 2 10.20p 0 0 0 0 0

# methyl proton chemical shiftshift 3 1.0p 0 0 0 0 0shift 4 1.0p 0 0 0 0 0shift 5 1.0p 0 0 0 0 0

# OH ... OH dipolar interactiondipole 1 2 -4452.8217 0 0 0

# OH ... methyl proton dipolar interactiondipole 1 3 -2966.9764 0.0 163.9 0dipole 1 4 -2966.9764 120.0 163.9 0dipole 1 5 -2966.9764 240.0 163.9 0

# methyl protons dipolar interactiondipole 3 4 -26763.7665 60 90 0dipole 3 5 -26763.7665 180 90 0dipole 4 5 -26763.7665 300 90 0

}

par {proton_frequency 500073117.4spin_rate 40000variable ssb 10variable i 1variable j 1variable rf 100000variable N 2sw spin_rate*ssbnp 2048crystal_file rep10gamma_angles 15start_operator I1zdetect_operator I1zverbose 1101

}

proc pulseq {} {global par

# here we keep only coherence between OHand CH3 protons (all others arediscarded)

5

matrix set 1 coherence {{1 1 0 0 0}{-1 -1 0 0 0}{1 0 1 0 0}{-1 0 -1 0 0}{1 0 0 1 0}{-1 0 0 -1 0}{1 0 0 0 1}{-1 0 0 0 -1}{ 0 1 1 0 0}{ 0 -1 -1 0 0}{ 0 1 0 1 0}{ 0 -1 0 -1 0}{ 0 1 0 0 1}{ 0 -1 0 0 -1}

}

maxdt 1.0

# 90 pulseset p90 [expr 0.25e6/$par(rf)]

# timing rotor synchronisationset tau2 [expr

0.5e6/$par(spin_rate)-2*$p90]

# dwell timeset dw [expr 1e6/$par(sw)]

for {set i 0} {$i < $par(ssb)} {incri} {

reset [expr $i*$dw]

delay $dwstore [expr $i+2*$par(ssb)]

# BaBa-2 block (2 rotor periods) for thecosine partreset [expr $i*$dw]pulse $p90 $par(rf) 0delay $tau2pulse $p90 $par(rf) 0pulse $p90 $par(rf) 90delay $tau2pulse $p90 $par(rf) 270pulse $p90 $par(rf) 0delay $tau2pulse $p90 $par(rf) 0pulse $p90 $par(rf) 270delay $tau2pulse $p90 $par(rf) 90

store $ifor {set j 1} {$j < $par(N)} {incr

j} {prop $i

}store $i

# BaBa-2 block (2 rotor period) for thesine partreset [expr $i*$dw]pulse $p90 $par(rf) 45delay $tau2pulse $p90 $par(rf) 45pulse $p90 $par(rf) 135delay $tau2pulse $p90 $par(rf) 315pulse $p90 $par(rf) 45delay $tau2pulse $p90 $par(rf) 45pulse $p90 $par(rf) 315delay $tau2pulse $p90 $par(rf) 135

store [expr $i+$par(ssb)]for {set j 1} {$j < $par(N)} {incr

j} {prop [expr $i+$par(ssb)]

}store [expr $i+$par(ssb)]

}

# Acquisitionresetprop 0store [expr 3*$par(ssb)]filter 1prop 0acqresetprop 0filter 1prop [expr $par(ssb)]acqfor {set i 1} {$i < [expr $par(np)/2]}

{incr i} {resetprop [expr 3*$par(ssb)]prop [expr (($i-1) %

$par(ssb))+2*$par(ssb)]store [expr 3*$par(ssb)]filter 1

6

prop [expr $i % $par(ssb)]acqresetprop [expr 3*$par(ssb)]filter 1prop [expr $i % $par(ssb) +$par(ssb)]acq

}}

proc main {} {global par

set f [fsimpson]set g [fdup $f]for {set i 1} {$i < $par(np)} {incr i

2} {set re [findex $f $i -re]set im [findex $f [expr $i+1] -re]fsetindex $g [expr ($i+1)/2] $re $im

}

for {set i [expr $par(np)/2+1]} {$i <=$par(np)} {incr i} {fsetindex $g $i 0.0e0 0.0e0

}

# save computed datafsave $g $par(name).fidfunload $ffunload $g

}

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