Intergrowth Family MFI--ION

Periodic Building Unit


Periodic Building Unit (PerBU):	Pentasil i layer

Layer symmetry	P -1

2D cell parameters	a = 20.09 Å	b = 13.14 Å	gamma = 90°
Comment	Adjacent pentasil chains in the layer are related by inversion centers

Connector

	Unit	-ION chain

References
	Villaescusa, L.A., Jian Li, J., Mayoral, A., Gao, Z.R. and Camblor, M.A.
		"Sandwich-Type Zeolite Intergrowths with MFI and the Novel Extra- Large Pore IDM‐1 as Ordered End-Members"
		Chem. Mater., 33, 7869-7877 (2021)

Connectivity pattern

Examples

The layers are stacked along the [001] direction using the following connectivity patterns

Symmetry Operation^*	Translation^*	Comment	Image
m	None	direct connection
m	None	connection via -ION chains
		If connectors are present on both sides of a layer, they are related to one another by the inversion centers in the layer.

^* relative to the previous layer

Alternative description
The intergrowth structure can be viewed as a stacking of 4 different layers:
   1   Pentasil i layer   (green)
   2   mirror image of the Pentasil i layer   (light green)
   3   layer of -ION chains   (blue)
   4   inverted layer of -ION chains   (dark blue)

The rules for stacking are that:
   1 can only be followed by 2 or 3
   2 can only be followed by 1 or 4
   3 can only be followed by 2
   4 can only be followed by 1

The stacking 1 2 1 2 1 2 is that of polymorph MFI.
The stacking 1 3 2 4 1 3 2 4 is that of polymorph -ION.


Effect on channel system
	The presence of connectors creates a dumbbell-shaped 16-ring opening to the sinusoidal channel along the [100] direction. Without the connectors, this is a round 10-ring opening.

Simplest ordered end members

Connectors are shown in blue. The different shades indicate that that they are not identical, but related to one another by an inversion center.
Adjacent PerBUs generated by the same connectivity pattern (with or without connectors in between) are shown with different shades of the same color for clarity.

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Polymorph MFI

Cell Parameters:	orthorhombic	P n m a: (# 62)
	a = 20.0900 Å	b = 19.7380 Å	c = 13.1420 Å
	α = 90.000°	β = 90.000°	γ = 90.000°
	Volume =	5211.3 Å³
Framework Density (FD_Si):	18.4

	Ring sizes (# T-atoms):	10 6 5 4
	Channel dimensionality:	Topological (pore opening > 6-ring): 3-dimensional

Maximum diameter of a sphere:
	that can be included	6.36 Å
	that can diffuse along	a: 4.7 Å	b: 4.46 Å	c: 4.46 Å
		addional volume data

Composite Building Units:


mor	cas	mfi	mel

In this space group and setting, the PerBUs are stacked along [010]

	Note: This polymorph corresponds to the ordered framework MFI

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Polymorph -ION

Cell Parameters:	orthorhombic	P n m a: (# 62)
	a = 20.0314 Å	b = 34.8780 Å	c = 13.2653 Å
	α = 90.000°	β = 90.000°	γ = 90.000°
	Volume =	9391.2 Å³
Framework Density (FD_Si):	17.0

	Ring sizes (# T-atoms):	16 10 6 5 4
	Channel dimensionality:	Topological (pore opening > 6-ring): 3-dimensional

Maximum diameter of a sphere:
	that can be included	6.75 Å
	that can diffuse along	a: 4.93 Å	b: 4.52 Å	c: 4.52 Å
		addional volume data

Composite Building Units:


mor	cas	stf	mfi	mel

In this space group and setting, the PerBUs are stacked along [010]

	Note: This polymorph corresponds to the ordered framework -ION

Disorder Example



	Simple example of a random stacking of MFI and -ION polymorphs

	The straight 10-ring channels along the stacking direction are not blocked by the random disorder.