Diapositive 1

About This Presentation

Title:

Diapositive 1

Description:

Marc Fourmigu . Chimie, Ing nierie Mol culaire et Mat riaux (CIMMA) ... Para-phenylenediamine oxidizes into radical cation, then into dication ... – PowerPoint PPT presentation

Number of Views:104

Avg rating:3.0/5.0

Slides: 58

Provided by: Four74

Category:

more less

Transcript and Presenter's Notes

Title: Diapositive 1

1
Chemistry of Molecular Conductors an Overview
Marc Fourmigué Chimie, Ingénierie Moléculaire
et Matériaux (CIMMA) UMR 6200 CNRS-Université
dAngers, UFR Sciences, Bât. K, 2 bd Lavoisier,
49045 ANGERS , France
E mail marc.fourmigue_at_univ-angers.fr
The Chemistry Dpt. Angers University
2
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Toward a control of the solid state
structures
VI. From the macro to the nano scale
Theoretician's dreams

3
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Toward a control of the solid state
structures
VI. From the macro to the nano scale
Theoretician's dreams

4
I. PREREQUISITES

Cristalline molecular conductors
? charge carriers
? delocalized and strong intermolecular
interactions
for sizeable band dispersion
Stable radical molecules (charged or neutral)
Solid state organization favoring intermolecular
interactions
but avoiding localized single bond formation

5
PREREQUISITES

Cristalline molecular conductors
? charge carriers
? delocalized and strong intermolecular
interactions
Stable radical molecules (charged or neutral)
Solid state organization favoring intermolecular
interactions
but avoiding localized single bond formation

6
TWO-STEP REDOX SYSTEMS
Deuchert, K. Hünig, S. Angew. Chem. Int. Ed.
Eng. 1978, 17, 875.
7
TWO-STEP REDOX SYSTEMS DONOR MOLECULES
E1/2 0.33 V vs. ECS E1/2 0.71 V
vs. ECS
Tetrathiafulvalene oxydizes into radical cation,
then into dication
8
TWO-STEP REDOX SYSTEMS ACCEPTOR MOLECULES
TCNQ reduces into radical anion, then into dianion
9
PREREQUISITES

Cristalline molecular conductors
? charge carriers
? intermolecular interactions
Stable radical molecules (charged or neutral)
Solid state organization favoring intermolecular
interactions but avoiding localized single bond
formation

10
A DELOCALIZED, TWO-ELECTRON SINGLE BOND
(TMTSF)22(Re6S6Cl8)2- 2 TMTSF pour un dianion
Dicationic dimers formation of a s bond
between two p type orbitals eclipsed
conformation leads to optimized
overlap diamagnetic, insulating salt
11
STABILIZATION OF MIXED VALENCE
(TTF)2(Re6S5Cl9)- 2 TTF for 1 monoanion
Cationic dimers bond-over-ring configuration
with a decreased overlap mixed-valence
dimer paramagnetic salt and the elementary
building block for conducting, mixed-valence
systems
K. Boubekeur, PhD. Thesis, University of Rennes
(France) 1988
12
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Toward a control of the solid state
structures
VI. From the macro to the nano scale
Theoretician's dreams

13
II. HISTORICAL DEVELOPMENTS
11 TCNQ salts exhibit a large variety of
conducting behaviors, depending on DE
Eox(donneur) Ered(TCNQ)
If DE lt 0, r 1 Full charge transfer charge
transfer salt If DE gt 0.25, r 0 neutral
complex charge transfer complex If 0 lt DE lt
0.25, 0 lt r lt 1 partial charge transfer, mixed
valence salt
14
TTF-TCNQ
Uniform segregated stacks (1D system) Metallic
conductivity Metal-insulator transition at TMI
54 K
15
TTF-TCNQ
Charge Transfert r 2 x 0.295
0.59 Incommensurate Periodicity 3.39 ? stacking
parameter below Peierls transition
16
TTF-TCNQ ANALOGS
HMTTF-TCNQ TMI 48, 43 K 2.38a x 2.78b x c r
0.72
HMTSF-TCNQ T 24 K Toward semi-metal a x 2.7b x
c with r 0.74
TSF-TCNQ TMI 29 K 2a x 3.15 b x c r 0.63
TCNQ is not necessary ! Cation radical salts
with spectator anions (Br, BF4, ClO4, PF6,
) obtained by chemical (Br2, I2, ) or
electrochemical oxidation (electrocristallization)

17
ELECTROCRYSTALLIZATION
Electrocrystallization of cation radical
salts (Bechgaard, Fabre) galvanostatic
oxidation of donor molecule Cation radical
salts precipitate on the anode if proper
conditions such as ? current density, ?
solvent(s), ? temperature, ?
concentrations, are found (evt. many trials)
P. Batail, K. Boubekeur, M. Fourmigué, J.-C. P.
Gabriel Chem. Mater. 1998, 10, 3005-3015.
18
FABRE (TMTTF) BECHGAARD (TMTSF) SALTS
First organic superconductors (Bechgaard,
Jérome, 1980) Pseudo 1D systems with dimerized
stacks quarter-filled ? half-filled systems A
very rich low-dimensional solid state physics
D. Jérome, Chem. Rev. 2004, 104, 5565
19
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Toward a control of the solid state
structures
VI. From the macro to the nano scale
Theoretician's dreams

20
III. SYNTHETIC ACTIVITY ON DONOR MOLECULES
21
CHALCOGEN SUBSTITUTIONS
Replacement of S with heavier (or lighter)
elements to increase the band dispersion
DTDAF D. Lorcy, N. Bellec, Chem. Rev. 2004, 104,
5185.
22
CHALCOGEN FUNCTIONALIZATION 2D STRUCTURES

Substituting with outer chalcogen atoms - - to
increase the 2D character
to suppress the Peierls transition
to stabilize metallic behavior
evt. to reach superconducting phases

23
2D STRUCTURES OF BEDT-TTF SALTS
Layered structures a, b, k, l, q phases
24
(BEDT-TTF)2(IBr2)
A-G pairs interacting along ab and along b 2D
electronic structure with closed Fermi
surface Superconducting transition at 3 K
R. P. Shibaeva, E. B. Yagubskii, Chem. Rev. 2004,
104, 5347 and refs therein
25
ROLE OF DISORDER IN BET-TTF SALTS
(BET-TTF)2Br.(H2O)3 A non-disordered, metallic
salt down to 2 K 2D Fermi surface and electronic
structure
C. Rovira, Chem. Rev. 2004, 104, 5289
26
UNSYMMETRICAL TTF DERIVATIVES
From 2D (EDT-TTF salts) to 1D (EDO-TTF salts)
systems Metal-insulator transition in
(EDO-TTF)2PF6 0,0,1,1, charge ordering
pattern
Synthesis J.-. Fabre, Chem. Rev. 2004, 104,
5133 (EDO-TTF)2PF6 A. Ota, H. Yamochi, G.
Saito, J. Mater. Chem. 2002, 12, 2600 S.
Aoyagi, K. Kato, A. Ota, H. Yamochi, G. Saito, H.
Suematsu, M. Sakata, M. Takata, Angew. Chem.
Int. Ed. 2004, 43, 3670.
27
SPATIAL EXTENSION OF THE TTF CORE (I)
A. Gorgues, M. Sallé, P. Hudhomme, Chem. Rev.
2004, 104, 5151.
28
SPATIAL EXTENSION OF THE TTF CORE (II)
Fused systems (Mizaki, Yamada) 2D metallic salts
with BDT-TTP and BDH-TTP These are NOT TTFs
anymore !
J. Yamada, H. Akutsu, H. Nishikawa, K Kikuchi,
Chem Rev. 2004, 104, 5057.
29
TTF DIMERS
Numerous molecules described Very few conducting
systems Solubility problems
M. Iyoda, M. Hasegawa, Y. Miyake, Chem. Rev.
2004, 104, 5085 M. Fourmigué, C. Mézière, E.
Canadell, D. Zitoun, K. Bechgaard, Adv. Mater.
1999, 11, 766
30
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Toward a control of the solid state
structures
VI. From the macro to the nano scale
Theoretician's dreams
Perspectives

31
IV. SYSTEMATIC INVESTIGATIONS OF COUNTER IONS
A. The basic library
Small, diamagnetic, spherical, tetrahedral or
octahedral anions Cl, Br, BF4, ClO4,
ReO4, PF6, AsF6, SbF6 Linear anions I3,
IBr2, ICl2, AuI2, Au(CN)2, Ag(CN)2 Larger,
tetrahedral, evt. magnetic anions GaCl4,
FeCl4, InBr4, FeBr4, MnCl4, CoCl4,
CuBr4 Larger, complex anions Pt(CN)42,
Cr(CN)63, Fe(CN)5(NO)2
32
IV. SYSTEMATIC INVESTIGATIONS OF COUNTER IONS
B. The polymeric library
Cyanide and thiocyanate anions Cu(NCS)2,
CuN(CN)2X, Cd(NCS)3 Bimetallic, oxalate
bridged anions MnCr(ox)3, MnRh(ox)3 PbI3,
Pb5/6?1/6I2
33
IV. SYSTEMATIC INVESTIGATIONS OF COUNTER IONS
C. The Big is beautiful library
Cluster anions Re6S5Cl9, Re6S6Cl82,
Re6S7Cl73, Mo6Cl142, Polyoxometallate
anions Mo6O192, PMo12O403, SiW12O404,
CoW12O406 Oxalate anions (H3O)Cr(ox)3 Coor
dination complex anions Cr(NCS)4(phen),
Cr(NCS)4(isoq)2
34
IV. SYSTEMATIC INVESTIGATIONS OF COUNTER IONS
D. The Dithiolene library
Magnetic complexes M(mnt)2, M Ni, Pt, Pd, Co,
Fe, Au Conducting complexes Ni(dmit)2,
Pd(dmit)2
R. Kato, Chem. Rev. 2004, 104, 5319.
35
IV. SYSTEMATIC INVESTIGATIONS OF COUNTER IONS
E. The organic/organometallic library
Radical anions TCNQ?, TCNQF4?, DCNQI?,
chloranil? Carboxylates, sulfonates,
phenolates, Polycyano anions C(CN)3,
CC(CN)232, C3C(CN)232, Organometallic
Cu(CF3)4, Ag(CF3)4, Au(CF3)4, Au(C6F5)2
U. Geiser, J. A. Schlueter, Chem. Rev. 2004, 104,
5203
36
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Toward a control of the solid state
structures
VI. From the macro to the nano scale
Theoretician's dreams
Perspectives

37
FIRST CONCLUSIONS
Synthetic chemistry of donor molecules
BDT-TTP or BDH-TTP good surprises are still
possible Dimeric systems are still largely
unexplored Functionalisation of the donor core
opens new perspectives The donor/counter ion
couple has been explored extensively Evolution
toward single component conductors (A.
Kobayashi, E. Fujiwara, H. Kobayashi, Chem. Rev.
2004, 104, 5243) Evolution toward
multi-functional materials (E. Coronado, P.
Day, Chem. Rev. 2004, 104, 5419) (T. Enoki, A.
Miyazaki, Chem. Rev. 2004, 104, 5449) Toward a
control of the organic/inorganic interface
Hydrogen bonding, halogen bonding Toward a
control of the crystal size and shape L.B.
films, Thin layer electrocrystallization What
theoreticians expect ?
38
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Control of the solid state structures
VI. From the macro to the nano scale
Theoretician's dreams

39
CONTROL OF THE SOLID STATE STRUCTURES
Hydrogen bonding Electrostatic, attractive,
directional interaction Hydrogen bond
motifs Cooperativity
Halogen bonding XX distances shorter than
the van der Waals radii Anisotropic electron
density (polar flattening)
40
TTFs FOR HYDROGEN BONDING
Phosphonates
Alcohols
Acids
Amides
Uracils
Imidazoles
M. Fourmigué, P. Batail, Chem. Rev. 2004, 104,
5379.
41
ACTIVATION OF HYDROGEN BONDING
(EDT-TTF-CONHMe)2Cl?H2O, 2D electronic
structure Metallic down to 2 K Activation of the
a-H atom Deactivation of the carbonyl O atom
42
ACTIVATION OF HYDROGEN BONDING
TTF-imidazole/Chloranil 1D electronic
structure TMI 170 K Activation of the a-H atom
of the TTF-imidazole Deactivation of the N-
atom Activation of the carbonyl O atom in the
chloranil anion
T. Murata, Y. Morita, K. Fukui, K. Sato, D.
Shiomi, T. Takui, M. Maesato, H. Yamochi, G.
Saito, K. Nakasuji, Angew. Chem. Int. Ed 2004,
43, 6343
43
TTFs FOR HALOGEN BONDING
Monohalogenated
Di-halogenated
Tetra-halogenated
M. Fourmigué, P. Batail, Chem. Rev. 2004, 104,
5379.
44
ACTIVATION OF HALOGEN BONDING
I ??? Br SrvdW 3.85 Å, exp 3.21 Å I ???
N(?C) SrvdW 3.55 Å, exp 2.88 Å
T. Imakubo, H. Sawa, R. Kato, Synth. Metals 1995,
73, 117.
45
ACTIVATION OF HALOGEN BONDING
(EDO-TTF-I2)2Ni(mnt)2 I ???
N(?C) SrvdW 3.55 Å, exp 3.041 Å
Mixed-valence metallic salt Segregated stacks
of EDO-TTF-I2 and Ni(mnt)2 Conducting EDO-TTF-I2
stacks halogen-bonded to 1D ferromagnetic
Ni(mnt)2 chains
J. Nishijo, E. Ogura, J. Yamaura, A. Miyazaki, T.
Enoki, T. Takano, Y. Kuwatani, M. Iyoda, Solid
State Commun. 2000, 116, 661.
46
ACTIVATION OF HALOGEN BONDING
(EDT-TTF-I2)2Pb5/6I23 a mixed-valence
metallic salt with the lacunary Pb5/6?1/6I2
polyanion with PbI2 structure Idonor??? Ianion
3.81, 4.09 Å (van der Waals gap 4.95 Å in PbI2)
T. Devic, M. Evain, Y. Moelo, E. Canadell, P.
Auban-Senzier, M. Fourmigué, P. Batail, J. Am.
Chem. Soc. 2003, 125, 3295.
47
CONCLUSIONS ON HYDROGEN/HALOGEN BONDING
? Hydrogen- or halogen bonding interactions
coexist with delocalized band structures for
metallic conductivity ? Hydrogen- or halogen
bonding interactions are enhanced in such salts
because of their (in part) electrostatic nature
? No superconductivity observed to
date Question to theoreticians Does the
rigidity of hydrogen- or halogen bonding in the
solid prevents a lattice softness required for
superconductivity ?
48
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Control of the solid state structures
VI. From the macro to the nano scale
Theoretician's dreams
Perspectives

49
FROM THE MACRO TO THE NANO SCALE
Bulk crystals the bigger, the best ?
electrocrystallization (P. Batail, K. Boubekeur,
M. Fourmigué, J.-C. P. Gabriel, Chem. Mater.
1998, 10, 3005-3015) ? reverse-current
electrocrystallization for very small
crystals (S. Hünig et al. Eur. J. Inorg. Chem.
1999, 899) Thin crystals for optical
measurements (transmission) for microelectronic
applications ? confined electrocrystallizatio
n (M. Thakur, R. C. Haddon, S. H. Glarum, J.
Cryst. Growth 1990, 106, 724) (A. Deluzet, S.
Perruchas, H. Bengel, P. Batail, S. Molas, J.
Fraxedas, Adv. Funct. Mater. 2002, 12, 123)
50
FROM THE MACRO TO THE NANO SCALE
Langmuir-Blodgett films Donor or acceptor
molecules made amphiphilic Mixedvalence
required for conductivity obtained by ? post
doping (I2) ? electrochemically during or after
deposition ? by combining donor and
acceptor The film structure strongly influences
the conductivity Controlling the intermolecular
interactions in 2D ? Toward hybrid
organic/inorganic multi-layers Langmuir-Blodgett
films (M. Clemente-Leon, E. Coronado, P.
Delhaes, C. J. Gomez-Garcia, C. Mingotaud, Adv.
Mater. 2001, 13, 574) Review article D. R.
Talham, Chem. Rev. 2004, 104, 5479.
51
CHEMISTRY OF MOLECULAR CONDUCTORS

I. Prerequisites
II. Historical developments
III. Synthetic activity on donor molecules
IV. Systematic investigations of counter ions
First conclusions
V. Control of the solid state structures
VI. From the macro to the nano scale
Theoretician's dreams

52
THEORETICIANS DREAMS
Th. Giamarchi (in Chem. Rev. 2004, 14,
5037) The Bechgaard salts are, in some sense,
too interesting materials, with too many
phenomena occuring at once. To better understand
these phenomena, it would be good to have other
compounds in which some degree of simplification
or new physics occurs. Three main directions
highlighted ? Non-dimerized systems ?
Interchain coupling ? Mott gap and doping
53
DREAM No 1 NON-DIMERIZED SYSTEMS

? Donor chains in Bechgaard salts are slightly
dimerized, hence
the conduction band splits into two bands and the
upper band is half filled
Electronic localization is associated with ¼ and
½-Umklapp electron
scattering processes
A non-dimerized, quarter-filled system is
expected to be a Mott insulator
with ¼ -Umklapp scattering only
Experimental realization in EDT-TTF-CONMe22AsF6

54
A QUARTER-FILLED SYSTEM EDT-TTF-CONMe22AsF6

? CH???O hydrogen bonds rigidify the stacks
along c
In both HT Pnma and LT P21/c forms, molecules
within a stack are
related to each other via a glide plane, hence
the uniform stacks

K. Heuzé, M. Fourmigué, P. Batail, C. Coulon, R.
Clérac, E. Canadell, P. Auban-Senzier, S. Ravy,
D. Jérome, Adv. Mater. 2003, 15, 1251.
55
DREAM No 2 INTERCHAIN COUPLING