chemistry and physics of low dimensional molecular conductors

Size: px

Start display at page:

Download "chemistry and physics of low dimensional molecular conductors"

Phoebe Edwards
6 years ago
Views:

1 chemistry and physics of low dimensional molecular conductors Patrick Batail UMR CNR 6200 MOLTECH Angers Ecole du GDR MICO 5-11 juin 2010 AUOI d (EDT-TTF-CONMe 2 ) 2 AsF 6 cristaux et photo Cécile Mézière

2 TTF HO TMTTF TMTF

3 a typical molecular metal: (TMTF) 2 + PF 6

electrocrystallization an invaluable tool for the construction of electroactive molecular solids one single, day-to-weeks experiment achieves: carriers generation carriers stabilization by

4 electrocrystallization an invaluable tool for the construction of electroactive molecular solids one single, day-to-weeks experiment achieves: carriers generation carriers stabilization by delocalization/localization within stacks / slabs (intermolecular conjugation) electrostatic self-assembly / auto-templating into bi-continuous O-I hybrid frameworks allows: halogen-bonded co-assembly into ternary systems upon engaging neutral functional p-conjugated spacers

in the presence of NaI Best crystals typically under controlled rhythmic reversal of the current flow in the

5 I org I inorg halogen bonding interactions associate in CH 3 CN : EDT-TTF- I 2 with either : the corner-sharing, perovskite-layerlike 2D polymer (BuNH 3+ ) 2 (PbI 4 2 ) or the edge-sharing 2D polymer PbI 2 in the presence of NaI Best crystals typically under controlled rhythmic reversal of the current flow in the e-cell (0.7 s in oxidation coupled to 0.3 s in reduction), see Hünig et al. Eur. J. Inorg. Chem 1999, 899. Thomas Devic

ÉVAIN, Y. MOËLO, E. CANADELL, P. AUBAN-ENZIER, M. FOURMIGUÉ, P. BATAIL J. Am.

6 e-crystallization upon controlled rythmic reversal of dc current flow poor crystal quality at constant current rythmic reversal 1 mm 1 mm T. DEVIC, M. ÉVAIN, Y. MOËLO, E. CANADELL, P. AUBAN-ENZIER, M. FOURMIGUÉ, P. BATAIL J. Am. Chem. oc. 125, 3295 (2003) early example, see Hünig et al., Eur. J. Inorg. Chem. 1999, 899

7 b-(i 2 -EDT-TTF) + 2[(Pb 5/6 1/6 I 2 ) 1/3 ] 3 ingle crystals!! a bi-continuous hybrid composite T. Devic pseudo-intercalation of b-slab into lacunar, edge-sharing (CdI 2 -type), [Pb (1-x) I 2 ] ( 2x) hexagonal single layers interfacial Halogen-bonding : C I I = 3.81 and 4.09 Å charge balance from lead site occupancy

8 electrocrystallization laboratory d-(edt-ttf-conme 2 ) 2 AsF 6 et d-(edt-ttf-conme 2 ) 2 Br b-(edt-ttf-i 2 ) 2 + [(Pb 5/6 1/6 I 2 ) 1/3 ] 3 b-(edt-ttf-i 2 ) 2 + [(Pb 2/3+x Ag 1/3 2xx I 2 ) 1/3 ] 3 x 0.05 b -(EDT-TTF-I 2 ) 2 PbI 3 H 2 O Kagome (EDT-TTF-CONH 2 ) 6 [Re 6 e 8 (CN) 6 ] single crystals by Cécile Mézière June 2006 b-(edt-ttf-i 2 ) 2 [HO 2 C CH=CH CO 2 ] 1-x [ O 2 C CH=CH CO 2 ] x [(rac), (R) et ()-(EDT-TTF-Me-Oxazoline)] 2 X (X = AsF 6, PF 6, Au(CN) 2 ) chemistry and physics of intermolecular interactions act in unisson

9 objectif cet après-midi : crystal engineering of p-conjugated systems: getting familiar with redox chemistry and intermolecular interactions how to reveal a hidden structural detail relevant to pertinent features of a complex electronic structure and lying behind a beautiful low dim physics

10 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and bands (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts 6. modify / control electronic structure 6.1 tune stoichiometry 6.2 tune anion charge 6.3 ternary phases by halogen bonding 6.4 [H + ]/[hole] mixed valence 6.5 chemical pressure

11 November 2004 Volume 104 Number 11

12 OUTLINE 1. electrocrystallization 2. redox chemistry

13 iegfried Hünig s Reversible 2-teps Redox ystems of the Violene Type X X n -e +e X X n -e +e resonance / conjugation X X n Y Y n -e +e Y Y n -e +e Y Y n Hückel formalism: treat heteroatom/group as a perturbation Chem. Rev. 104, 5535 (2004)

14 X X n -e +e X X n -e +e X X n -e -e TTF TTF + TTF 2+ tetrathiafulvalene

15 iegfried Hünig s Reversible Two-teps Redox ystems of the Violene Type X X n -e +e X X n -e +e resonance / conjugation X X n Y Y n -e +e Y Y n -e +e Y Y n NC CN NC CN NC CN NC CN NC CN NC CN TCNQ 2 TCNQ TCNQ Chem. Rev. 104, 5535 (2004)

16 Hückel formalism: treat heteroatom/group as a perturbation propene k p k i p i j j j

17 propene

18 TTF HO TMTTF TMTF

19 characterization of redox properties: cyclic voltammetry experiments I V

21 Torrance Mol. Cryst. Liq. Cryst. 1985, 126, 5567 p-donor vs p-acceptors

22 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure

23 intermolecular interactions p p -p p overlap, p-p, vdw, H- and Hal-bonding direct the structure weak Directing the tructures and Collective Electronic Properties of Organic Metals: the Interplay of Overlap Interactions and Hydrogen Bonds K. HEUZÉ, M. FOURMIGUÉ, P. BATAIL, E. CANADELL, P. AUBAN-ENZIER Chem. Eur. J. 5(9), (1999) Activation of Hydrogen and Halogen Bonding Interactions in Crystalline Molecular Conductors M. FOURMIGUE, P. BATAIL Chem. Rev. 104, (2004)

24 p-p interactions interactions between p-conjugated closed shell molecules quadrupoles quadrupoles interactions + + repulsion + + C. A. Hunter and J. K. M. anders, J. Am. Chem. oc. 1990, 112, 5525

25 C. A. Hunter and J. K. M. anders, J. Am. Chem. oc. 1990, 112, 5525

26 pentacene, a paradigm for p-p interactions / stacking herring-bone pattern of intermolecular interactions C. A. Hunter and J. K. M. anders, J. Am. Chem. oc. 1990, 112, 5525

27 hydrogen bonds 1) normal hydrogen bonds 2) weak hydrogen bonds: C sp3 H X and C sp2 H X D H d+ A d electrostatic, between an H-bond donor and an H-bond acceptor directional vanishes very slowly with distance Fourmigué, Batail Chem. Rev. 2004, 104, 5379

28 O H O et N H O: normal hydrogen bonds NH 4+ OH 2 19 kcal mole ev HO H Cl 13.5 kcal mole ev HO H OH 2 5 kcal mole ev CH X: weaker hydrogen bonds HC C H OH kcal mole ev H 2 C=C H OH 2 1 kcal mole ev 1 kcal mole 1 = ev Chem. Rev. 2004, 104, 5382

29 [C 6 H 5 NH 3+ ][Me 3 TTF PO 3 H ] e [Me 3 TTF + PO 3 H ] a neutral, zwitterionic radical A. Dolbecq et al. Chem. Eur. J., 2(10), (1996)

30 REDOX ACTIVATION TRONG H-bond acceptor character DENIED! O N Me H H izeable H-bond donor character Redox state (off/on) Intermolecular interactions Molecular recognition (binding strenght) - e + e Competition : charges and spins localization (magnetism) vs delocalization (transport). + Chem. Commun (2003) O H N H Me ENHANCED!

31 b -(EDT-TTF-CONHMe) 2 [Cl H 2 O] O N H d + Cl - d + H.+ not involved Chem. Mater. 2000, 12, b HOMO-HOMO interaction energies I ev II III IV V

32 b -(EDT-TTF-CONHMe) 2 [Cl H 2 O] Chem. Mater. 2000, 12,

33 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension)

34 low dimensional molecular solids intermolecular interactions (those which direct the structure: p p -p p overlap, vdw, H- and Hal-bonding) are weak understanding crystal and electronic structure correlation: easier (back of the envelop arguments) in materials with stronger, covalent and/or ionic interactions it is a much more delicate task to look for such correlations for systems with weak interactions because we lack the kind of feeling and control of the relative weight of the different interactions, all of which are weak

extended-hückel tight-binding band structure calculations Grant Whangbo Hoffmann Burdett Mori Canadell anisotropy of the system in the momentum space Purpose:

35 extended-hückel tight-binding band structure calculations Grant Whangbo Hoffmann Burdett Mori Canadell anisotropy of the system in the momentum space Purpose: how to reveal a hidden, apparently innocuous structural detail relevant to pertinent features of their electronic structures and lying behind a beautifull physics?

36 basic concepts: orbitals and bands in one-dimension working with small, simple things:

39 a n c 0 c 1 c 2 c 3 c 4 k = e ikna c n n Roald Hoffmann Angew. Chem. Int. Ed. 1987, 26,

41 Band Width that the bands extend unsymmetrically around their origin (energy of a free H atom at ev) is a consequence of the inclusion of overlap: for two levels, a dimer: E ± = H AA ± H AB 1 ± AB the bonding E + combination is les stabilized than the antibonding one E is destabilized

42 orbitals and bands in one dimension

44 see how they run: k = e ikna c n p x along x : x? the band of p orbitals runs down from zone center to zone edge

45 stack of square planar d 8 PtL 4 complexes try predict the approximate band structure of K 2 Pt(CN) 4 and K 2 Pt(CN) 4 Br 0.3 without calculation eclipsed staggered the Pt Pt distance has been shown to be inversely related to the degree of oxidation of the materials

46 topology of d block orbitals

47 types of overlap p d type : strong, axis of rotation type p: medium, lateral, co-planar type d: weak, face-to-face

48 inventory of all possible modes of overlap within pairs of orbitals s, p or d along z z overlap type only between orbitals s, p or d z 2 p p x, p y, d xz or d yz d d x 2 y 2 or d xy

49 try and see how they run (along z)? a p band out of N p orbitals: runs up, moderate yet sizeable dispersion a p band out of d xz s: runs down, moderate yet sizeable dispersion a band out of d z2 s: runs up, dispersion is large a d band out of d xy s: runs up, barely (not quite flat though)

50 Bloch functions at the zone center (k = 0) and the zone edge (k = p/a)

51 (2p z ) i orbitals of the 4 carbon atoms (i = 1, 2, 3, 4) of cyclobutadiene

52 z y x

53 d x 2 y 2 interacts strongly with 4 ( type) 4 y x d z d x 2 y 2 1

54 the d orbitals of square-planar ML 4 unit

55 d d p

56 predicted considerations of band width and orbital topology extended Huckel calculation at Pt Pt = 3.0 Å

57 Pt(II) d 8 where are the electrons? e F K 2 [Pt II (CN) 4 ] 3H 2 O K 2 [Pt II (CN) 4 ]Br 0.33 H 2 O

59 more than one unit per unit cell : chemists fold bands too!

60 More than one electronic unit in the unit cell. Folding bands.

62 butadiene A A

63 butadiene

64 butadiene A A

65 a

67 stays still there before going back down (equilibrium) V that goes in = V that goes out

68 goes through a mid-point in energy where the net number of bonding states equals that of antibonding states

69 folding bands

70 a = 3a a = 4a

72 band diagram of a dimerized system. Peierls. electron count. 2k F the chemist s intuitive feeling for what a model chain of hydrogen atoms would do:

73 H n, uniform chain H n, dimerized chain orbitals at the Fermi level for the chain (H 2 ) n

74 band diagram of the dimerized system (H2)n

76 electron count 2 molecules Pt(CN) 4 per unit cell a = 10 3 e F 2p a x = 2 x 5p 6a K 2 [Pt II (CN) 4 ]Br 0.33 H 2 O 3p/6a 4p/6a 5p/6a

77 K 2 [Pt II (CN) 4 ]Br 0.33 H 2 O electron # is: 2 x 5p 6a e F 3p/6a 4p/6a 2 k F = p 3a = a* 3 in the momentum space

78 2.4 polyacetylene

79 N

80 frontier p orbitals LUMO HOMO low lying states

81 N

82 N N

83 discrete, fully ionic dimers in [(TTF + ) 2 ][(I 3 ) 2 ] HO TTF + HO TTF + HO TTF + HO TTF + strong bonding: type p p p p overlap eclipsed and diamagnetic HO TTF + + HO TTF +

84 discrete, mixed valence dimer in (TTF) 2 + [Re 6 5 Cl 9 ] HO TTF + HO TTF + HO TTF HO TTF + HO TTF + + HO TTF + milder bonding: p type p p p p overlap slipped and paramagnetic

85 3.360 Å Å vdw p p recouvrements p p p p ( ) + p (TTF) 2 2+ (TTF) 2 +

86 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts

87 TCNQ N N C C C C N N LUMO

88 TTF TCNQ

89 between C 2pz s

90 antibonding (k = 0)

91 bonding Y (k = p/b)

92 TTF TCNQ E(k) 0 k F p/b k

93 at = 0, the in-phase combination is bonding

94 TTF TCNQ = 0.59 E(k) 0 k F p/b k uncommensurate band filling

95 TTF TCNQ recent first principles B calculation by Pablo Ordejón and Enric Canadell Barcelona

97 TTF-TCNQ Jérome Chem. Rev. 2004, 104, 5565

98 TMTF-DMTCNQ = 0.5!! Peierls transition suppressed at 9 kbars!! Metallic down to liquid helium temperatures under 10 kbars instead of 0.59 in TTF-TCNQ Jérome Chem. Rev. 104, 5575 (2004)

99 Jérome Chem. Rev. 2004, 104 p. 5575

100 TMTF-DMTCNQ = 0.5!! Peierls transition suppressed at 9 kbars!! Metallic down to liquid helium temperatures under 10 kbars instead of 0.59 in TTF-TCNQ Jérome Chem. Rev. 104, 5575 (2004)

101 a typical molecular metal: (TMTF) 2 + PF 6

102 TTF HO TMTTF TMTF

103 the molecule is symmetric 3.66 Å 3.63 Å centers of symmetry allow for any amount of dimerization 2 to 1 e e e e 2 molecules per unit in chain along a Bechgaard and Fabre salts

104 a typical molecular metal: (TMTF) 2 PF = 3 e F 0 p/2a p/a 0 p/a a = 2a p/4a

105 dimerization slightly dispersed in transverse direction also E F (TMTF) 2 PF 6 2 bands 3 electrons half-filled band (a*/2, 0) (0,0) (0, b*/2) (a*/2, b*/2) ( a*/2, b*/2)

106 nesting vector

107 Jérome Chem. Rev. 2004, 104, p and p. 5577

108 Jérome Chem. Rev. 2004, 104 p. 5578

109

110 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts 6. modify / control electronic structure

111 Roald Hoffmann How Chemistry and Physics Meet in the olid tate Angew. Chem. Int. Ed. Engl. 1987, 26, Jeremy K. Burdett Chemical Bonding in olids Oxford University Press, 1995 Christophe Iung, Enric Canadell Description orbitalaire de la structure électronique des solides 1. De la molécule aux composés 1D Ediscience international, Paris, 1997 Roger Rousseau, Marc Gener, Enric Canadell tep-by-step construction of the electronic structure of molecular conductors: Conceptuals aspects and applications Adv. Funct. Mater. 2004, 14, 201

112 Chem. Rev. 1991, 91,

113 1D / 2D Band tructures and Fermi urfaces

114 very pure samples the combination of very pure samples and admixtures of 1D/2D F makes for a rich low dimensional physics, especially under high B s see, Mark V. Kartsovnik Chem. Rev. 2004, 104, 5737

a series of 2D metals yet with two different types of charge carriers with different dimensionality a-(bedt-ttf) 2 [M + Hg 2+ (QCN ) 4 ] M = Tl, K, NH 4 ; Q =, e Mark V. Kartsovnik Chem. Rev.

115 a series of 2D metals yet with two different types of charge carriers with different dimensionality a-(bedt-ttf) 2 [M + Hg 2+ (QCN ) 4 ] M = Tl, K, NH 4 ; Q =, e Mark V. Kartsovnik Chem. Rev. 2004, 104, 5737 all exhibit giant dh oscillations: 2D closed sections of F (16% of first Brillouin zone) rooom temperature crystal structures, B and F very similar some exhibit a density wave instability: nested 1D parts of F Rousseau, Figueras, Canadell J. Mol. truct. (Theochem) 1998, 424, 135 see also Organic uperconductors by Ishiguro, Yamaji, aito pringer-verlag 1998

116 modifying the electronic structure 0 p/a

117 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts 6. modify / control electronic structure 6.1 tune anion charge

118 [Ti 2 F 8 (C 2 O 4 )] 2 [Ta 2 F 11 ] [(TMTF) ] 2( +) 3 [Ti 2 F 8 (C 2 O 4 )] [(TMTF)] + 3 [Ta 2 F 11 ] ynth. Met. 1988, 22, 201 ynth. Met. 1991, 41-43, 1939

119 predict band diagram and conductivity uniform chains metallic e F 6 2 i.e. 4 electrons in three bands: highest one is empty insulating 6 1 i.e. 5 electrons in three bands: highest one is half-filled 0 k p/b 0 k p/b b = 3b 3:1 2 p/6a 3:1

120 predict band diagram and conductivity trimerized chains metallic e F insulating 3:1 2 p/6a 3:1 b = 3b

121 [Ti 2 F 8 (C 2 O 4 )] 2 [Ta 2 F 11 ] Y [(TMTF) ] 2( +) 3 [Ti 2 F 8 (C 2 O 4 )] [(TMTF)] + 3 [Ta 2 F 11 ]

122

123 molecular engineering and band filling change the anion charge change electron count by tuning the stoichiometry Modulating the Framework Negative Charge Density in the ystem BDT-TTP + /[Re 6 5 Cl 9 1 ]/[Re 6 (/e) 6 Cl 8 2 ]/[Re 6 7 Cl 7 3 ]: Templating by Isosteric Cluster Anions of Identical ymmetry and hape, Variations of Incommensurate Band Filling, and Electronic tructure in 2D Metals. PERRUCHA, K. BOUBEKEUR, E. CANADELL, Y. MIAKI, P. AUBAN-ENZIER, C. PAQUIER, P. BATAIL J. Am. Chem. oc. 130(11), (2008)

124 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts 6. modify / control electronic structure 6.1 tune anion charge 6.2 tune stoichiometry

125 Morita-Nakasuji s TTF-imidazole N N H N N H Angew. Chem. Int. Ed. 43, 6343 (2004)

126 Morita-Nakasuji s TTF-imidazole e Cl Cl O N N H N N H N N H O Cl Cl redox activated hydrogen bonding allows to control stoichiometry Angew. Chem. Int. Ed. 43, 6343 (2004)

127 e N N H N N H N N H O O O O redox activated hydrogen bonding allows control of stoichiometry

128 (TTF-Im) 2 (CHL) redox activated hydrogen bonding allows control of stoichiometry

129 (TTF-Im) 2 (CHL) P 1 uniform stacks

130 (TTF-Im) 2 (CHL) TTF Im + spin only Heisenberg chain of spins on uniform chloranil stacks

131 (TTF-Im) 2 (CHL)

132 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts 6. modify / control electronic structure 6.1 tune anion charge 6.2 tune stoichiometry

133 EDT-TTF-CONH 2 vs Re 6 e 8 (CN) 6 ] 4 /3 Batail et al. Chem. Rev. 2001, 101, 2037 redox active, luminescent, hexanuclear, molecular chalcogenide cluster 0.3 V/CE asaki, Fedorov et al. Chem. Lett. 1999, 1121 how H-bonding express octahedral symmetry of inorganic cluster anion

134 6 EDT-TTF-CONH 2 + Re 6 e 8 (CN) 6 ] 4 /3 3

135 R3 a = (2) Å a = (2) V = Å 3 Kagome net = 1/2

136 (EDT-TTF-CONH 2 ) 6 (4- )+ [Re 6 e 8 (CN) 6 ] (4- ) b HOMO-HOMO intradimer ev interdimer ev Canadell

137 (EDT-TTF-CONH 2 ) 6 (4- )+ [Re 6 e 8 (CN) 6 ] (4- ) NO OVERLAP 2D Canadell

138 (EDT-TTF-CONH 2 ) 6 (4- )+ [Re 6 e 8 (CN) 6 ] (4- ) e F ( = 0) e F ( = 1) Canadell

139 single crystal esr H H Coulon, Clérac

140 ER conductivity d 0 / 2 1/ 2 = 8 cm -1

141 carriers at room temperature: (EDT-TTF-CONH 2 ) 6 (3.92)+ [Re 6 e 8 (CN) 6 (4) ] e cluster, diamagnetic [Re 6 e 8 CN) 6 3( ) ] e, Jahn-Teller active, paramagnetic = ½ cluster (EDT-TTF-CONH 2 ) 6 (4)+ [Re 6 e 8 (CN) 6 ] (4) (EDT-TTF-CONH 2 ) 2 (1)+ (EDT-TTF-CONH 2 ) 2 (1)+ (EDT-TTF-CONH 2 ) 2 (2)+ below transition charge disproportionation charge ordering

142 (TTF) 2 2+ (TTF) 2 +

143 triclinic 100 K charge localization coupled to molecular motion [EDT-TTF-CONH 2 + ] 2 téphane Baudron Lika Zorina [EDT-TTF-CONH 2 ] 2 +

Mott localization below 200 K 100 300 T(K) mixed

144 Mott localization below 200 K T(K) mixed valence, slipped fully oxidized, more ecliped 2+ charges are ordered 2+ XRD vs P: andra Carlsson, Dave Allan, Paul Attfield - U of Edimburg

145 Conclusion: Mott localization M-I transition coupled to phase transition molecular motion (softness of interfacial H-bond interactions). A. BAUDRON, P. BATAIL, C. COULON, R. CLERAC, E. CANADELL, V. LAUKHIN, R. MELZI, P. WZIETEK, D. JEROME, P. AUBAN-ENZIER,. RAVY, J. Am. Chem. oc. 127(33), (2005)

146 try and control the property HOW? keeping with Kagome lattice change anion charge!

147 substitute one Re(III) for one Os(IV) [Re III 6e 8 (CN) 6 ] 4 [Re III 5Os IV e 8 (CN) 6 ] 3 Baudron, Batail + Tulski, Long France-Berkeley Program

148 (EDT-TTF-CONH 2 ) 4 (3)+ [Re 5 Ose 8 (CN) 6 ] (3) (EDT-TTF-CONH 2 ) 6 (4)+ [Re 6 e 8 (CN) 6 ] (4)

149 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts 6. modify / control electronic structure 6.1 tune anion charge 6.2 tune stoichiometry 6.3 ternary phases by halogen bonding

150 O H O et N H O: normal hydrogen bonds NH 4+ OH 2 19 kcal mole ev HO H Cl 13.5 kcal mole ev HO H OH 2 5 kcal mole ev CH X: weaker hydrogen bonds HC C H OH kcal mole ev H 2 C=C H OH 2 1 kcal mole ev halogen bonds: comparable to normal hydrogen bonds C Cl N C 2.4 kcal mole ev CF 3 I NH 3 6 kcal mole ev 1 kcal mole 1 = ev Chem. Rev. 2004, 104, 5382

151 halogen bonding in the solid state: as strong and even more directional than hydrogen bonding d r max C X d +d r min direction of maximum attractive electrostatic interaction towards electron-rich (lone pairs) region of Lewis bases polar flattening O, C=O, C= sp 3 and sp 2 amines (pyridine) N C goups I>Br>Cl Fourmigué, Batail Chem. Rev., 104(11), (2004)

152 halogen bonding in the solid state: as strong and even more directional than hydrogen bonds C X 1 2 X C type I 1 = 2 X X C C type II 1 = 90, 2 = 180 Desiraju et al. JAC, 111, 8725 (1989) Fourmigué, Batail Chem. Rev. 104, (2004)

153 EDT TTF + [Re 6 e 8 (CN) 6 ] 4 also probing the extend of a covalent component to halogen bonding: * C I N C I I C I a current crystal engineering issue

154 (EDT-TTF) 8 (p-bib) [Re 6 e 8 (CN) 6 ] Anne-Lise Barrès 8:1:1 n:2:1 n:3:1

155 halogen-bonded co-polymer I I (EDT-TTF) 8 (p-bib) [Re 6 e 8 (CN) 6 ]

156 (EDT-TTF) 8 (p-bib) [Re 6 e 8 (CN) 6 ] A.-L. BARRÈ, A. EL-GHAYOURI, L. V. ZORINA, E. CANADELL, P. AUBAN-ENZIER, P. BATAIL Chem. Commun (2008)

157 OUTLINE 1. electrocrystallization 2. redox chemistry 3. intermolecular interactions, and their redox activation, direct the structure 4. orbitals and band (in one dimension) 5. decipher B of TTF-TCNQ, Bechgaard salts 6. modify / control electronic structure 6.1 tune stoichiometry 6.2 tune anion charge 6.3 ternary phases by halogen bonding 6.4 [H + ]/[hole] mixed valence 6.5 chemical pressure

158 d (EDT-TTF-CONMe 2 ) 2 X, X = AsF 6, Br genuine 3/4-filled band Mott insulators H H O NMe 2 H H C 1 symmetry H K. HEUZÉ, M. FOURMIGUÉ, P. BATAIL, C. COULON, R. CLÉRAC, E. CANADELL, P. AUBAN-ENZIER,. RAVY, D. JÉROME Adv. Mater. 15, (2003)

159 Me 2 N O H Me 2 N O H Me 2 N O H Me 2 N O H [±c/2] NMe 2 O H NMe 2 O H NMe 2 O H NMe 2 O H apply glide plane P2 1 /c

glide plane imposed by the C 1 Molecular ymmetry P2 1 /c @ 150 K t t glide planes @ 1/4 and 3/4 along b glide plane imposes stack

160 glide plane imposed by the C 1 Molecular ymmetry P K t t glide 1/4 and 3/4 along b glide plane imposes stack uniformity non dimerized, 2 molecules, 1 hole per unit along chain: band is ¼-filled with holes t = + 71 mev despite criss-cross overlap:

161 band structure and Fermi surface: a sizeable t Transfer integrals Br vs [AsF 6 ] Z along stack X total bandwidth is 0.31 ev for AsF 6 : very similar to (TMTTF) 2 Br which, however, has a small dimerization gap of ev Enric Canadell

162 Mott insulator!!: the underlying mechanism for fermions localization can only come from the quarter-filling umklapp AsF 6 - Mott gap mostly controlled by the on-site and nearest neighbor interactions Auban-enzier Jérome Adv. Mater. 15, (2003)

163 decrease Mott gap by applying chemical pressure: V (AsF 6 ) = V (Br ) + 76 Å 3 7 kbar

164 band structure and Fermi surface: a sizeable t Transfer integrals Br vs [AsF 6 ] Z along stack X total bandwidth is 0.31 ev for AsF 6 : very similar to (TMTTF) 2 Br which, however, has a small dimerization gap of ev Enric Canadell

165

166 (EDT-TTF-CONMe 2 ) 2 X Transport sous pression : c (P) à T ambiante X = AsF 6 (1bar) = 0.03 (.cm) -1 X = Br (1bar) = 1 (.cm) -1 Conductivité (.cm) X = Br (EDT-TTFCONMe 2 ) 2 X T = 295K X = AsF P. Auban-enzier C. Pasquier D. Jérome Pression (kbar) (TMTTF) 2 PF 6 ) (1bar) = 40 (.cm) -1 forte augmentation de (P) à basse pression (régime localisé) puis dépendance linéaire (idem (TM) 2 X) (régime métallique) à partir de X= AsF 6 : décalage de 7 kbar / X=Br et de 15 kbar / (TMTTF) 2 PF 6 Conductivité (.cm) AsF 6 X = Br X = AsF 6 (EDT-TTFCONMe 2 ) 2 X T = 295K Pression (kbar) Br = 7 kbar

167 Temperature (K) NON-DIMERIZED Q-1D ¼ filled systems (EDT-TTF-CONMe 2 ) 2 X, X=AsF 6, Br X = AsF 6 X = Br 1000 T CO ( P)) Conductor 1D T T* 100 Insulator CO P CO ( P)) T MI ( ) Conductor 2D T MI () 10 T AF ( 13 C T 1 ) Antiferromagnetic T AF ( 1 H T 1 ) T MI ( // ) Insulator CDW FL Pressure (kbar) D dim = 0 CO with AF ground state, no P, no DW, no C CO / AF CDW FL Phase diagram of quarter-filled band organic salts, [EDT-TTF-CONMe 2 ] 2 X, X =AsF 6 and Br P. AUBAN-ENZIER, C. R. PAQUIER, D. JEROME,. UH,. E. BROWN, C. MEZIERE, P. BATAIL Phys. Rev. Lett. 102, (2009)

168 INGLE CRYTAL 13 C NMR AsF 6 13 C NMR pectrum recorded at T = 200 K and applied field B = T. For arbitrary orientations, there are four non-equivalent sites (labelled A1, A2, B1, B2) teve uh, tuart E. Brown, UCLA

169 T 1-1 (s -1 ) AsF sites A1,A2 sites B1,B2 13 C T 1-1 (T) Charge rich site B 10 1 Charge depleted site A A B temperature(k) B / A = 9 / 1 T 1-1 (B) / T 1-1 (A) = ( B / A ) 2 large and T independent charge ratio r B / r A = 9 / 1 10 <T< 200K Charge ratio 3 / 1 in (DI-DCNQI) 2 Ag, K.Hiraki, K. Kanoda., PRL 80, 4737 (1998) (TMTTF) 2 AsF 6, F. Zamborszky et al., PRB 66, (R) (2002)

170 full refinement and analysis of symmetry of 3D CO structure based on single crystal synchrotron X-ray data identify an anti-phase, static modulation wave of Br - atoms, in synchronicity with on-site localization of holes Leokadiya Zorina, ergey imonov, Cécile Mézière, Enric Canadell, teve uh, tuart E. Brown, Pierre Fertey, Pascale Foury-Leylekian, Jean-Paul Pouget, Patrick Batail J. Mater. Chem. 19, (2009)

171 (DI-DCNQI) 2 Ag REFINED WIGNER TRUCTURE T. Kakiuchi, Y. Wakabayashi, H. awa, T. Itou, K. Kanoda, Phys. Rev. Lett., 2007, 98, a-(bedt-ttf) 2 I 3 T. Kakiuchi, Y. Wakabayashi, H. awa, T. Takahashi, T. Nakamura, J. Phys. oc. Jpn., 2007, 76, (EDO-TTF) 2 PF 6. Aoyagi, K. Kato, A. Ota, H. Yamochi, G. aito, H. uematsu, M. akata, M. Takata, Angew. Chem. Int. Ed., 2004, 43, (BEDT-TTF) 2 RbZn(CN) 4 M. Watanabe, Y. Noda, Y. Nogami, H. Mori, J. Phys. oc. Jpn., 2004, 73, 921.

172 PAUL ATTFIELD s WORK ON CO IN INORGANIC powder neutron diffraction studies on half-doped manganites (Pr 0.5 Ca 0.5 MnO 3, TbBaMn 2 O 6, YBaMn 2 O 6 ) and magnetite (Fe 3 O 4 ) J. P. Attfield, olid t. c., 2006, 8, R. J. Goff, J. P. Wright, J. P. Attfield, P. G. Radaelli, J. Phys. Cond. Mat., 2005, 17, R. J. Goff, J. P. Attfield, Phys. Rev. B, 2004, 70, J. P. Wright, J. P. Attfield, P. G. Radaelli, Phys. Rev. Lett., 2001, 87,

173 Br Pmna at 300 K for averaged structure one independent molecule in asymetric unit do NOT allow for charge ordering

174 twinned monoclinic structure below 190 K Pmna Lika Zorina P2 1 /a keeps with local two-fold axial symmetry about a

175 Br MONOCLINIC P2 1 /a ORTHORHOMBIC Pmna Change in the γ lattice angle across the structural phase transition. Blue rhombuses and red circles below the transition are data points for the two different twin domains in the monoclinic phase.

176 P2 1 /a 150 K

177 Bruker 4-circle CCD, Angers ynchrotron OLEIL Pmna, 2?, 4 collected independent R 1 [I>2 (I)] a large collection of systematic absences reflections to work with in orthorhombic symmetry

178 compatible with Pmnn, P2nn, P P2nn analysis of synchrotron data

179 two independent molecules in asymetric unit 2b in agreement with CO

180

de-activated concerted mechanism long range

181 activation of large collections of CH O hydrogen bonds in synchronicity with CO: activated charge disproportionation carriers crystallize mixed valence metallic de-activated concerted mechanism long range electrostatic modulation Wigner structure Mott insulator

182 synchrotron data collected at Br absorption hedge modulation of Br displacements

183 P2nn anti-phase modulation

184 3D charge ordered structure P2nn compatible with ferroelectricty

185 Br static modulation wave

186 Pmna P2nn despites the occurrence of CO, stacks appear to remain essentially uniform

187 Résumé chimie et physique des interactions intermoléculaires faibles à l unisson dans les conducteurs moléculaires en basse dimension

A Variety of Ground States in Salts of Unsymmetrical TTFs. Marc Fourmigué

A Variety of Ground States in Salts of Unsymmetrical TTFs Marc Fourmigué Sciences Chimiques de Rennes, UMR 6226 CNRS-UR1 Equipe Matière Condensée et Systèmes Electroactifs Campus de Beaulieu, 35042 RENNES,