4th EucheMs chemistry congress

thursday, 30-Aug 2012
s848
chem. Listy 106, s587–s1425 (2012)
solid state Chemistry Materials chemistry/New materials
Molecular and Hybrid Porous Crystals
o - 5 1 5
ModeLLinG CoMPLex StruCture, PoroSity,
And Co-oPerAtive diffuSion BehAviour in
MoLeCuLAr PorouS orGAniC MAteriALS
A. trewin 1 , M. LewiS 1 , d. hoLden 1 ,
J. JordAnoviC 1 , K. JeLfS 1 , A. CooPer 1
1 University of Liverpool, Chemistry, Liverpool, United Kingdom
Materials with molecular-scale porosity are important in a
wide range of applications such as gas storage, molecular
separation, and heterogeneous catalysis. Understanding complex
gas sorption behaviour can give important information about the
[1, 2]
structural properties of a material and gas uptake mechanisms.
We are developing novel methodologies for investigating the
structure, time-dependent pore connectivity, co-operative
diffusion mechanisms, and stepped gas sorption uptake behaviour.
Discrete molecules tend to pack efficiently in the solid state
resulting in minimal void volume, hence very few molecular
materials exhibit permanent porosity. Molecular porous materials
are able to respond locally to the presence of a guest leading to
the potential for diffusion of molecules that would not be expected
by analysis of the static crystalline structure.
Here, we analyse molecular porous solids, for example Cage
3 that packs to form a diamondoid 3-D pore structure running
through restrictive cage windows. [3, 4] We show that by analysing
the dynamic surface area properties of the molecular material
as guest molecules diffuse, we can identify and understand
the co-operative diffusion mechanisms. This will allow us to
potentially design materials with porosity tailored for a specific
application.
references:
1. T. Tozawa et al,Nature Mater. 2009, 8, 973–978.
2. J. T. A. Jones et al, Angewandte Chemie 2011, 123, 775–779;
3. J. T. A. Jones et al, Nature 2011, 474, 367–371;
4. S. Jiang et al, Nat Commun 2011, 2, 207.
Keywords: Microporous materials; Molecular dynamics;
Surface analysis; Solid state structures;
Hybrid Zeolites and Nanochemistry
4 th EucheMs chemistry congress
o - 5 1 6
eni CArBon SiLiCAteS: truLy hyBrid
orGAniC-inorGAniC zeoLiteS
r. MiLLini 1
1 Eni s.p.a. - refining&marketing division, San Donato Milanese
Research Center - Physical Chemistry Dept., San Donato
Milanese, Italy
ECS materials form a new class of porous crystalline
organic-inorganic hybrid aluminosilicates recently discovered,
whose synthesis resembles that of zeolites, involving the
hydrothermal treatment of a reaction mixture composed by
NaAlO and a bridged silsesquioxanes [(R'O) Si–R–Si(OR') ,
2 3 3
R = alkyl or aromatic groups; R' = Me or Et] as sources of alumina
and silica, respectively. A set of ECS materials has been
synthesized so far, by varying the nature of the bridged
silsesquioxanes and the synthesis conditions. The characterization
of these materials demonstrated that most part of the silica
precursor does not undergo Si-C hydrolysis and are present
unchanged in the crystalline phases. Though challenging because
of the complexity of the XRD patterns, the determination of the
crystal structure of some ECS materials was successful, providing
important information on their characteristics. The ECS structures
known so far consist of a stacking of alternating inorganic and
organic layers and possess microporous systems, whose
architecture varies from a phase to another. Taking into account
the materials obtained with R = phenylene, different situations
exist. ECS-2 is a clathrasil-like structure since the arrangement of
the phenylene rings in the organic layers produces large cages not
open to the exterior. In the structure of ECS-3 the relative
arrangement of the phenylene rings generates an open porosity
running within the organic layer only. More interesting is
ECS-14 because it represents the first example of hybrid material
with the structure related to a known zeolite framework type, i.e.
AFI common to AlPO-5 and the silica SSZ-25 phases.
The 12-membered ring linear channels are present even in
ECS-14, crossing the inorganic and organic layers which stack
along [001]. For other ECS materials, the structure determination
is in progress and the results will be illustrated and discussed to
provide an overview of this interesting class of materials.
Keywords: Zeolites; Microporous materials; Layered
compounds; X-ray diffraction; Electron diffraction;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc