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A Neutral Zwitterionic Molecular Solid
Author(s) -
ElGhayoury Abdelkrim,
Mézière Cécile,
Simonov Sergey,
Zorina Leokadiya,
Cobián Manuel,
Canadell Enric,
Rovira Carme,
Náfrádi Bálint,
Sipos Balázs,
Forró László,
Batail Patrick
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001875
Subject(s) - zwitterion , protonation , chemistry , deprotonation , adduct , redox , crystallography , hydrogen bond , dication , ionic bonding , electron transfer , stereochemistry , ion , molecule , photochemistry , inorganic chemistry , organic chemistry
We report on the acid ethylenedithiotetrathiafulvaleneamidoglycine (EDT‐TTF‐CO‐NH‐CH 2 ‐CO 2 H; 1 ; EDT‐TTF=ethylenedithiotetrathiafulvalene) and the 1:1 adduct [(EDT‐TTF) .+ ‐CO‐NH‐CH 2 ‐(CO 2 ) − ][(EDT‐TTF)‐CO‐NH‐CH 2 ‐(CO 2 H)]⋅CH 3 OH ( 2 ), a new type of hydrogen‐bonded, 1:1 acid/zwitterion hybrid embrace of redox peptidics into a two‐dimensional architecture, an example of a system deliberately fashioned so that oxidation of π‐conjugated cores toward the radical‐cation form would interfere with the activity of the appended ionizable residues in the presence of a templating base during crystal growth. First‐principles calculations demonstrate that, notwithstanding preconceived ideas, a metallic state is more stable than the hole‐localized alternatives for a neat 1:1 neutral acid/zwitterion hybrid. The inhomogeneous Coulomb field associated with proton‐shared, interstacks OH⋅⋅⋅O hydrogen bonds between the ionizable residues distributed on both sides of the two‐dimensional π‐conjugated framework leads, however, to a weak hole localization responsible for the activated but high conductivity of 1 S cm −1 . This situation is reminiscent of the role of the environment on electron transfer in tetraheme cytochrome c , in which the protonation state of a heme propionate becomes paramount, or ion‐gated transport phenomena in biology. These observations open rather intriguing opportunities for the construction of electronic systems at the interface of chemistry and biology.