Table 1 Internal volumes of host molecule cryptophane-A and derivatives 1 and 2, guest volumes, and packing coefficients.

From: Crystallographic observation of 'induced fit' in a cryptophane host–guest model system

Guest

Host

Internal volume (Å3)*

Guest volume (Å3)

Packing coefficient †

'Collapsed'

CS-2

—

—

—

Partial occupancy

CC-1‡

87

—

—

H2O

Crypt-A

88

18

0.20§

MeOH

2

84

33

0.39

Xe

2 (conf. 1)∥

89

42

0.47

 

2 (conf. 2)∥

87

42

0.48

 

1

85

42

0.49

 

Crypt-A

89

42

0.47

CDCl3

2 (conf. 1)∥

102

72

0.71

 

2 (conf. 2)∥

98

72

0.73

  1. *Internal volumes were calculated using Deep View/Swiss Pdb Viewer.
  2. †Packing coefficient is guest volume divided by host internal volume.
  3. ‡Diffuse electron density was observed inside the CC-1 cavity, which cannot be assigned to an encapsulated guest but is likely due to trace water.
  4. §This value is based on one bound water molecule, whereas partial electron density corresponding to water in seven different positions was observed.
  5. ∥Some crystal structures gave two conformers, which differed slightly in the orientations of the side chains and in their calculated internal volumes.
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