IM-18: DO Family

Intergrowth Family IM-18

Periodic Building Unit


	Periodic Building Unit (PerBU):	Layer of isolated zig-zag chains

	Layer symmetry	P m m (2)

	Comment	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.

Connector

	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

Symmetry Operation^*	Translation^*	Comment	Image
	0	d4r units in position 1
	1/2a	d4r units in position 2
	1/4a
	-1/4a

^* relative to the previous layer of connectors

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.

Disorder along b: arrangements of the rows of d4r unit connectors
The arrangement of the rows of d4r units is not necessarily periodic along b. Each row can be the same as the neighboring one or shifted by 1/2a.

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

	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 [001] and the layers are stacked along [100]

	Note: This polymorph corresponds to the ordered framework ITW