4th EucheMs chemistry congress

wednesday, 29-Aug 2012
s844
chem. Listy 106, s587–s1425 (2012)
solid state Chemistry Materials chemistry/New materials
Novel Materials and Molecular interactions
o - 4 1 2
PorouS AMorPhouS orGAniC CAGeS:
An exPeriMentAL And MoLeCuLAr dynAMiC
SiMuLAtion Study.
S. JiAnG 1 , A. trewin 1 , A. CooPer 1
1 University of Liverpool, Department of Chemistry, Liverpool,
United Kingdom
Email: aicooper@liv.ac.uk
The design of porous organic molecular solids where
packing is dictated by weak van der Waals forces is attracting
considerable attention. We have developed a series of organic cage
molecules that can be used for the construction of self-assembled
crystalline porous materials. Furthermore, we have found these
cage molecules can badly pack, creating permanent porosity in
the amorphous solid state. Interestingly, the gas selectivity in these
amorphous cage materials can be fine tuned by varying the ratio
of reagents in the reaction. A better understanding of this
phenomenon will aid in the optimization and development of
industrial applications of these amorphous materials in separation
and catalytic process.
An alternative approach for characterizing these amorphous
materials is based on molecular simulations. We developed a
methodology to generate simulated structures of amorphous cage
materials. All simulated models are characterized by their porosity
with surface area, pore size distribution, density and microporous
volume. The results show good agreement with available
experimental data. The dynamic diffusion of gas molecules
(mainly H , N ) through cavities or pores of amorphous organic
2 2
cages were investigated using MD simulations. The trajectory of
H in amorphous cage 1 exhibits a broader range of displacement
2
compared to N , which indicates a faster diffusion of H .
2 2
Therefore, amorphous cage 1 displays gas selectivity for H over 2
N . We also suggest that the enhanced porosity in these amorphous
2
solids results predominantly from the extrinsic porosity.
references:
1. Jiang, S.; Jones, J. T. A.; Hasell, T.; Blythe, C. E.;
Adams, D. J.; Trewin, A.; Cooper, A. I. Nat Commun
2011, 2, 207
Keywords: Molecular dynamics; Micropore materails; Cage
compounds; Nanostructures;
Novel Materials and Molecular interactions
4 th EucheMs chemistry congress
o - 4 1 3
AMinoGuAnidine And diAMinoGuAnidine AS
AdAPtive CAtioniC BuiLdinG BLoCKS in
orGAnoSuLfonAte StruCtureS
d. G. duMitreSCu 1 , M. BArBoiu 2 , A. vAn der Lee 2 ,
y. M. LeGrAnd 2
1 University Politehnica of Bucharest, FACSM Organic
Chemistry Department, Bucharest, Romania
2 Institut Européen des Membranes, Adaptive Nanostructures,
Montpellier, France
Crystal engineering is a very delicate process which depends
on many factors, and, as a consequence the final structure can
rarely be predicted. Crystal engineering usually overcomes these
obstacles by relying on strong, directional interactions like
hydrogen bonding and dipolar forces.
The structural backbone of one of the most versatile and
widely used systems, guanidinium-sulfonate assemblies, is a
honeycomb lattice of R2 (8) H-bond rings which assemble into
2
ribbons and larger R3 (12) patterns. The numerous papers
6
published on this subject provide ample amounts of data on the
effect of organic R substituent on crystal packing and overall
structure type (bilayer, brick etc.).
To our knowledge no attempt was made to change the
cationic component in these systems, the guanidinium moiety.
The aim of the current work is to investigate the structural
versatility of aminoguanidine and diaminoguanidine as cationic
components together with representative organic sulfonates.
The 7 new crystal structures demonstrate the versatility of
these new cationic components to form supramolecular
hydrogen-bonding assemblies. Furthermore, aminoguanidine
proved to be adaptable, by forming a R2 (10) dimer in the
2
structures where the total number of hydrogens available of
H-bonding exceeds the total number of H-bond acceptors.
Diaminoguanidine presented this motif in all the structures
studied, with the orientation of the elongated dimer mimicking
the width of the organic group from the sulfonates.
Keywords: crystal engineering; hydrogen-bond patterns;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc