ECNU-23: DO Family

Periodic Building Unit (PerBU):

Layer symmetry

2D cell parameters

a = 10.50 Å

b = 13.86 Å

gamma = 90°

To facilitate understanding of the connectivity patterns shown below, O atoms that connect to a single row of 4-ring units have been highlighted in the CFI layer shown to the right.

Intergrowth Family ECNU-23

2-dimensional disorder of the units connecting ordered layers

Periodic Building Unit

Connecting unit

	Connecting unit	4-ring

References


		Liu, X., Yi Luo, Y., Mao, W., Jiang, J., Xu, H., Han, L., Junliang Sun, J. and Wu, P.
			"3D electron diffraction unravels a new zeolite ECNU-23 from the “pure” powder sample of ECNU-21"
			Angew. Chem. Int. Ed., 59, 1166-1170 (2020)

Connectivity pattern

Each CFI layer is generated from the previous one by a mirror plane. The CFI layers themselves are fully ordered in 3 dimensions. However, the rows of 4-ring unit connectors can be disordered along both b and c, making the disorder in this family 2-dimensional.

Examples

Positions of 4-ring unit connectors in a row
There are two possible positions for a row of 4-ring units above the CFI layer. The position of the first 4-ring unit (along a) determines the positions of all the other 4-ring units in that row.

Symmetry Operations	Translation	Comment	Image
	0	4-ring units in position 1
	1/2a	4-ring units in position 2

Examples

Disorder along b: layers formed by the rows 4-ring unit connectors
The arrangement of the rows of 4-ring units is not necessarily periodic along b. Each row can be the same as the neighboring one or shifted by 1/2a.

First row	Next row	Comment	Image
position 1	position 1	shift of 0a^*
position 1	position 2	shift of 1/2a^*

^* relative to the previous row of connectors

Examples

Disorder along c: stacking of the layers of connectors
The 4-ring units in the connecting layers can also be disordered along c. The rows of 4-ring unit connectors can be stacked along the [001] direction using either of the following connectivity patterns

First layer	Second layer	Comment	Image
position 1	position 1	shift of 0a + 1/2b ^*
position 1	position 2	shift of 1/2a + 1/2b ^*

^* relative to the previous row of connectors

Effect on channel system
The disorder does not block the channel system. However, the 8-ring channel becomes sinusoidal when both 4-ring positions are present in a single layer of 4-ring units (i.e. it is no longer straight as in polymorph A or B below).