IM-18: DO Family

Periodic Building Unit (PerBU):

Layer of isolated zig-zag chains

Layer symmetry

2D cell parameters

a = 10.48 Å

b = 7.55 Å

gamma = 90°

To facilitate understanding of the connectivity patterns shown below, O atoms that connect to a single row of d4r units have been highlighted in the layer of isolated zig-zag chains shown to the right.

Intergrowth Family IM-18

2-dimensional disorder of the units connecting ordered layers

Periodic Building Unit

Connecting unit

	Connecting unit	d4r

References


		Cichocka, M.O., Lorgouilloux, Y., Smeets, S., Su, J., Wan, W., Caullet, P., Bats, N., McCusker, L.B., Paillaud, J.L. and Zou, X.D.
			"Multidimensional disorder in zeolite IM-18 revealed by combining transmission electron microscopy and X-ray powder diffraction analyses"
			Crystal Growth Des., 18, 2441-2451 (2018)

Connectivity pattern

Examples

Positions of d4r unit connectors in a row
There are two possible positions for a row of d4r units above two neighboring zig-zag chains in the layer. The position of the first d4r unit (along a) determines the positions of all the other d4r units in that row.

Symmetry Operations	Translation	Comment	Image
	0	d4r units in position 1
	1/2a	d4r units in position 2


Second row identical to first with no shift along a	Second row shifted by 1/2a with respect to first

Examples

Disorder along c: stacking of the layers of connectors
Each layer of zig-zag chains is generated from the previous one (gray) by a mirror plane (green) or a translation of 1/4a. The zig-zag layers themselves are ordered along c. However, the d4r units in the connecting layers can also be disordered along c, making the disorder 2-dimensional (along both b and c). The rows of d4r unit connectors can be stacked along the [001] direction using either of the following connectivity patterns

Symmetry Operations	Translation^*	Comment	Image
	1/4a
	-1/4a

^* relative to the previous layer of connectors

Effect on channel system
The disorder can block one or both of the straight 10-ring channels (e.g. those present in polymorphs A and B) when both d4r positions are present in a single layer of d4r units (see polymorph C).

Simplest ordered end-members

Connectors are shown in light blue.
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.


Polymorph EOS

Cell Parameters:	monoclinic	P 1 2/m 1 (# 10)
	a = 9.0869 Å	b = 7.5548 Å	c = 10.4762 Å
	α = 90.000°	β = 108.333°	γ = 90.000°
	Volume =	682.7 Å³
Framework Density (FD_Si):	17.6

	Ring sizes (# T-atoms):	10 8 6 5 4
	Channel dimensionality:	Topological (pore opening > 6-ring): 3-dimensional

Maximum diameter of a sphere:
	that can be included	4.96 Å
	that can diffuse along	a: 3.72 Å	b: 4.43 Å	c: 3.01 Å
		[0 1 0] : 4.43 Å
		addional volume data

Composite Building Units:


	d4r		mtw

In this space group and setting, the ordered connecting rows are along [001] and the layers are stacked along [100]

	Note: This polymorph corresponds to the ordered framework EOS


Polymorph IM-18_B

Cell Parameters:	orthorhombic	P m m a (# 51)
	a = 17.1828 Å	b = 7.5138 Å	c = 10.4477 Å
	α = 90.0000°	β = 90.0000°	γ = 90.0000°
	Volume =	1348.9 Å³
Framework Density (FD_Si):	17.8

	Ring sizes (# T-atoms):	10 8 6 5 4
	Channel dimensionality:	Topological (pore opening > 6-ring): 3-dimensional

Maximum diameter of a sphere:
	that can be included	5.1 Å
	that can diffuse along	a: 3.88 Å	b: 4.54 Å	c: 2.88 Å
		[0 1 0] : 4.54 Å
		addional volume data

Composite Building Units:


	d4r		mtw

In this space group and setting, the ordered connecting rows are along [001] and the layers are stacked along [100]

	Note: This polymorph has NOT been observed as a pure ordered material


Polymorph ITW

Cell Parameters:	monoclinic	C 1 2/m 1 (# 12)
	a = 10.4496 Å	b = 15.0277 Å	c = 8.9537 Å
	α = 90.000°	β = 105.640°	γ = 90.000°
	Volume =	1354.0 Å³
Framework Density (FD_Si):	17.7

	Ring sizes (# T-atoms):	8 6 5 4
	Channel dimensionality:	Topological (pore opening > 6-ring): 2-dimensional

Maximum diameter of a sphere:
	that can be included	4.73 Å
	that can diffuse along	a: 2.78 Å	b: 1.54 Å	c: 3.95 Å
		addional volume data

Composite Building Units:


	d4r

In this space group and setting, the ordered connecting rows are along a and the layers are stacked along [001]

	Note: This polymorph corresponds to the ordered framework ITW