Probing the conformational properties of guest molecules in solid inclusion compounds via EXAFS spectroscopy: bromine K-edge EXAFS studies of the bromocyclohexane/thiourea and trans-1-bromo-2-chlorocyclohexane/thiourea inclusion compounds

1995 ◽  
Vol 91 (10) ◽  
pp. 1497 ◽  
Author(s):  
Ian J. Shannon ◽  
Matthew J. Jones ◽  
Kenneth D. M. Harris ◽  
M. Rafiq H. Siddiqui ◽  
Richard W. Joyner
Keyword(s):  
Inclusion Compounds ◽  
Exafs Spectroscopy ◽  
Solid Inclusion ◽  
Guest Molecules ◽  
Conformational Properties

Structural properties of the guest species in diacyl peroxide/urea inclusion compounds: an X-ray diffraction investigation

1990 ◽  
Vol 431 (1882) ◽  
pp. 245-269 ◽  
Keyword(s):  
Single Crystal ◽  
Structural Properties ◽  
Inclusion Compounds ◽  
X Ray Diffraction ◽  
Channel Axis ◽  
Guest Molecules ◽  
X Ray ◽  
Urea Inclusion Compounds ◽  
Diacyl Peroxide ◽  
Urea Inclusion

In this paper we report single crystal X-ray diffraction studies of urea inclusion compounds containing diacyl peroxides (dioctanoyl peroxide (OP), diundecanoyl peroxide (UP), lauroyl peroxide (LP)) as the guest component. In these inclusion compounds, the host (urea) molecules crystallize in a hexagonal structure that contains linear, parallel, non-intersecting channels (tunnels). The guest (diacyl peroxide) molecules are closely packed inside these channels with a periodic repeat distance that is incommensurate with the period of the host structure along the channel axis. Furthermore, there is pronounced inhomogeneity within the guest structure: within each single crystal, there are regions in which the guest molecules are three-dimensionally ordered, and other regions in which they are only one-dimensionally ordered (along the channel axis). Although it has not proven possible to ‘determine’ the guest structures in the conventional sense, substantial information concerning their average periodicities and their orientational relationships with respect to the host has been deduced from single crystal X-ray diffraction photographs recorded at room temperature. For OP/urea, UP/urea and LP/urea, the guest structure in the three-dimensionally ordered regions is monoclinic, and six types of domain of this monoclinic structure can be identified within each single crystal. The relative packing of diacyl peroxide molecules is the same in each domain, and the different domains are related by 60° rotation about the channel axis. For each of these inclusion compounds, the offset between the ‘heights’ of the guest molecules in adjacent channels is the same ( ca . 4.6 Å (4.6 x 10 -10 m)) within experimental error, suggesting that the relative interchannel packing of the guest molecules is controlled by a property of the diacyl peroxide group. In addition to revealing these novel structural properties, the work discussed in this paper has more general relevance concerning the measurement and interpretation of single crystal X-ray diffraction patterns that are based on more than one three-dimensionally periodic reciprocal lattice. Seven separate reciprocal lattices are required to rationalize the complete X-ray diffraction pattern from each diacyl peroxide/urea crystal studied here.

scholarly journals Homogeneous photochemical reactions in solid inclusion compounds

2002 ◽  
Vol 58 (s1) ◽  
pp. c143-c143
Author(s):  
T. Lavy ◽  
M. Botoshansky ◽  
N. Shakkour ◽  
S. Speiser ◽  
M. Kaftory
Keyword(s):  
Inclusion Compounds ◽  
Photochemical Reactions ◽  
Solid Inclusion
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