CIT-13: DO Family

Periodic Building Unit (PerBU):

Layer symmetry

2D cell parameters

a = 10.50 Å

b = 13.50 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 CFI layer shown to the right.

Intergrowth Family CIT-13

2-dimensional disorder of the units connecting ordered layers

Periodic Building Unit

Connecting unit

	Connecting unit	d4r

References


		Kang, J.H., Xie, D., Zones, S.I., Smeets, S., McCusker, L.B. and Davis, M.E.
			"Synthesis and characterization of CIT-13, a germanosilicate molecular sieve with extra-large pore openings"
			Chem. Mater., 28, 6250-6259 (2016)

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 d4r unit connectors can be disordered along both b and c, making the disorder in this family 2-dimensional.

Examples

Positions of d4r unit connectors in a row
There are two possible positions for a row of d4r units above the CFI 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

Examples

Disorder along b: layers formed by the rows 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.

First row	Next row	Comment	Image
position 1	posotopn 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 d4r units in the connecting layers can also be disordered along c. The rows of d4r 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 10-ring channel becomes sinusoidal when both d4r positions are present in a single layer of d4r units (i.e. it is no longer straight as in polymorph A or B below).