In:
Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), Vol. 9, No. 33 ( 2021), p. 10777-10786
Abstract:
Electrocrystallization of tetramethyl-bis(ethylenedithio)-tetrathiafulvalene (TM-BEDT-TTF) (1) as pure ( S , S , S , S ) and ( R , R , R , R ) enantiomers in the presence of ( n -Bu 4 N) 2 (Mo 6 O 19 ) and chloroform or bromoform afforded a series of four isostructural enantiopure radical cation salts [( S / R )-1] 9 (Mo 6 O 19 ) 5 ·(CHX 3 ) 2 (X = Cl, Br) crystallizing in the trigonal non-centrosymmetric space group R 32. In the formula unit there are six donors of type A and three donors of type B showing, respectively, (ax, ax, eq, eq) and all-ax conformations (ax = axial, eq = equatorial) of the methyl substituents. The donors form a hexagonal network in the ab plane with a helical twist between them leading to lateral orbital overlap interactions. Electrocrystallization of the racemic donor provided the compound [( rac )-1] 2 (Mo 6 O 19 ) which crystallized in the monoclinic system P 2 1 / n . Single crystal resistivity measurements show semiconducting behaviour of the enantiopure materials with a relatively high room temperature conductivity of 0.8–1.2 S cm −1 , but rather insensitive to applied pressures of up to 2.3 GPa. Analysis of the electronic structure of the conducting solids through extended Hückel tight-binding band structure calculations indicates a Mott insulator behaviour explaining the semiconducting character and suggests that these compounds are valuable candidates for Dirac cone materials. Further insight into the conducting properties is provided by preliminary field effect transistor measurements.
Type of Medium:
Online Resource
ISSN:
2050-7526
,
2050-7534
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2021
detail.hit.zdb_id:
2702245-6
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