Article

Charge separation in mesoporous aluminosilicates

Research on Chemical Intermediates (impact factor: 0.7). 04/2012; 34(5):551-564. DOI:10.1163/156856708784795699

ABSTRACT EPR spectroscopy has been used to investigate spontaneous and/or photo-induced electron transfer between adsorbed organic
molecules and the mesoporous aluminosilicate MCM-41 host. Spontaneous electron transfer occurs from the host to electron acceptor
molecules with sufficiently favourable reduction potentials (TCNE, TCNQ, 1,4-benzoquinone, 1,4-naphthaquinone and 1,4-anthraquinone),
provided the MCM-41 contains aluminium and the radical anion yield correlates with the aluminium content of the host. The
semiquinone radical anions are interacting strongly with exposed Al3+ sites, whereas the TCNE and TCNQ radical anions are loosely bound and can be washed from the host. Radical cation formation
is observed when electron donor molecules with favourable oxidation potentials are adsorbed in MCM-41 containing aluminium,
and the radical cations formed interact with exposed Al3+ sites. This work shows that aluminium-containing MCM-41 contains both electron donating and electron accepting sites which
may intervene in intra-molecular charge separation processes in adsorbed organic molecules.

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Keywords

1,4-anthraquinone
 
adsorbed organic molecules
 
Al3+ sites
 
aluminium content
 
aluminium-containing MCM-41
 
electron donor molecules
 
EPR spectroscopy
 
favourable oxidation potentials
 
favourable reduction potentials
 
intra-molecular charge separation processes
 
mesoporous aluminosilicate MCM-41 host
 
photo-induced electron transfer
 
radical anion yield correlates
 
Radical cation formation
 
radical cations
 
semiquinone radical anions
 
spontaneous
 
Spontaneous electron transfer
 
TCNQ
 
TCNQ radical anions
 

Hongxian Han