Joseph W. Lyding

Highly conductive metallophthalocyanine assemblies. Structure, charge transport, and anisotropy in the metal-free molecular metal H2(Pc)I

Abstract That a metal ion is not required for high electrical conductivity is unequivocally demonstrated by structural, charge transport, optical, and magnetic characterization of the simplest phthalocyanine “molecular metal” H 2 (Pc)I. The crystal structure consists of staggered H 2 (Pc) +0.33 units stacked at 3.251(3) A intervals and parallel chains of I − 3 counterions. At 300 K, σ ‖ = 700 Ω −1 cm −1 and σ ‖ σ⊥ > 500 . At 15 K, σ ∼ reaches a maximum of ca. 4000 Ω −1 cm −1 and falls only to ca. 3500 Ω −1‖ cm −1 at 1.5 K. Analysis of single crystal polarized specular reflectance data (ir to uv) yields ω p = 6360(30) cm −1 and a tight-binding bandwidth of 1.3(1) eV. The magnetic susceptibility is Pauli-like ( X S = 2.21(5) × 10 −4 emu mol −1 ) except for a small, sample dependent Curie component.

Cofacial assembly of partially oxidized metallomacrocycles as an approach to controlling lattice architecture in low-dimensional molecular "metals". Probing band structure-counterion interactions in conductive [M(phthalocyaninato)O]n macromolecules using nitrosonium oxidants

This contribution reports an integrated chemical and physicochemical investigation of the consequences of doping the cofacially joined metallomacrocyclic polymers [M(Pc)O],, M = Si and Ge, with the nitrosonium salts NOX-, X= BF4-, PF6-, and SbF6-. In the case of [si(Pc)o],, doped products {[si(Pc)O]X,], are obtained with a limiting stoichiometry y = 0.36 (essentially identical with band-fillings obtained with halogenaxidants). In contrast, NOXdoping results in decomposition of [Ge(Pc)O],. Upon incremental NOXdoping of [Si(Pc)O],,, transmission infrared spectra reveal the progressive growth of electronic absorption, and transmission optical spectra reveal the formation of Pc K radical cation species. Studies of the NOXdoping process by X-ray diffractometry suggest that it is largely inhomogeneous. Computer-assisted analysis of the { [Si(Pc)O]X,),, powder diffraction data (aided by judiciously chosen model compounds) indicates crystal structures closely analogous to those of {[S~(PC)O](I~)~,~,],,, {[S~(PC)O](B~,)~,,,},,, N ~ ( P C ) ( C I O ~ ) ~ , ~ , and N ~ ( P C ) ( B F ~ ) ~ , , ~ . The data can be indexed in the tetragonal space group P4/mcc, Z = 2, with a = 13.70 (7) A, c = 6.58 (4) A, phthalocyanine staggering angle = 40 (2) (X= BF,-); a = 13.98 (6) A, c = 6.58 (4) A; phthalocyanine staggering angle = 40 (2) (X= PF6-); a = 14.31 (4) A, c = 6.58 (4) A, phthalocyanine staggering angle = 40 (2) (X= SbF6-). It appears that the Xions are disordered along c. ESR spectra reveal nearly free electron g values, in accord with the ligand-centered T radical character of the oxidation. As a consequence of the pronounced unidimensionality and minimal interaction of the carriers with heavy atoms, X-band powder ESR line widths are rather narrow (2.9-0.36 G) and decrease in the order I< > SbF6> PF6> BF4-. For {[Si(Pc)O](BF,),,,},, the line width is virtually temperature-independent from 4 to 300 K. Variable temperature (4-300 K) static magnetic susceptibility studies of the {[Si(Pc)O]X,}, materials reveal a small, sample-dependent Curie-like component and a Pauli-like, weakly temperature dependent contribution. Within experimental error, the Pauli-like susceptibility is independent of X-. Optical reflectivity studies of these materials reveal a plasma edge in the infrared. A Drude analysis of the data yields plasma frequency and tight-binding bandwidth parameters which are essentially independent of X-. Four-probe electrical conductivity studies of polycrystalline {[Si(Pc)O]X,& samples reveal a sharp increase of conductivity with increasing y. The temperature dependence of the data can be most convincingly fit to a transport model involving fluctuation-induced carrier tunneling through parabolic potential barriers that separate the high conductivity regions. As for the other collective properties, the charge transport properties are relatively insensitive to X-. A thermochemical analysis (Born-Haber cycle) indicates that the energetics of [Si(Pc)O], doping with Br,, I,, and NOXare surprisingly similar. The small magnitude of the band structure-counterion interactions in the {[Si(Pc)O]X,J, materials is attributed both to the local electronic and molecular structure of the phthalocyanine subunits as well as the overall stacking rigidity imposed by the -(Si-0-), chains. The structural, optical, magnetic, and charge transport characteristics of low-dimensional molecular metalsn2 are a sensitive function of various electrostatic and covalent interactions that occur between the molecular array forming the band structure and charge-compensating off-axis counterions (e.g., the partially oxidized multimolecular assembly in A). The nature and magnitudes of these interactions doubtless have a crucial influence (1) (a) Department of Chemistry. (b) Department of Electrical Engineering and Computer Science. (2) (a) Proceedings of the International Conference on the Physics and Chemistry of Low-Dimensional Synthetic Metals (ICSM 84); Pecile, C.; Zerbi, G.; Bozio, R.; Girlando, A., Eds.; Abano Terme, Italy, June 17-22, 1984. Mol. Cryst. Liq. Cryst. 1985, 117-121. (b) Williams, J. M. Prog. Inorg. Chem. 1985, 33, 183-220. (c) Wudl, F. Acc. Chem. Res. 1984, 17, 227-232. (d) Greene, R. L.; Street, G. B. Science (Washington, DC) 1984, 226, 651-656. (e) Extended Linear Chain Compounds; Miller, J. S . , Ed.; Plenum Press: New York, 1982; Vols. 1, 2, and 3. ( f ) Proceedings of the International Conference on Low-Dimensional Conductors; Epstein, A. J.; Conwell, E. M., Eds.; Boulder, Colorado, August 9-14, 1981. Mol. Cryst. Liq. Cryst. 1981-1982, 77, 79, 81, 83, 85, 86, Parts A-F. (g) Jerome, D.; Schulz, H. J. Ado. Phys. 1982,31,299-490. (h) The Physics and Chemistry of Low-Dimensional Solids; Alcacer, L., Ed.; D. Reidel: Dordrecht, 1980. (i) Highly Conducting One-Dimensional Solids; Devreese, J. T.; Evrard, R. P.; van Doren, V. E., Eds.; Plenum Press: New York, 1979. X -

ENFORCED SEGREGATED STACKING IN METALLOMACROCYCLIC 'METALS. ' NEW INFORMATION ON PHTHALOCYANINE DONOR-ACCEPTOR INTERACTIONS.

Abstract The chemical, structural, optical and electrical conductivity characteristics of the cofacially joined metallophthalocyanine polymer [Si(Pc)O]n are probed in response to incremental doping by organic (dichlorodicyanoquinone) and inorganic (NO+BF4 −, NO+PF6 −) oxidants of greatly differing structural and electronic characteristics. The achievable degree of partial oxidation, the homogeneity of the doping process, and the macroscopic mechanism of charge transport appear to be remarkably similar.

Phthalocyanine-based electrically conductive, processible molecular/macromolecular hybrid materials

Abstract This contribution relates new information on the properties of electrically conductive, processible Ni(Pc)/polymer/I 2 hybrid materials. Both the temperature and composition dependence of the electrical conductivity of Ni(Pc)/Kevlar/I 2 fibres are strongly reminiscent of the behaviour of composites. Using a variant of our fibre spinning methodology, it is also possible to produce Ni(Pc)/Kevlar/I 2 ribbons. Polarized resonance Raman spectroscopy indicates that the ribbons are structurally anisotropic (Ni(Pc)I c axes are preferentially aligned in the extrusion direction), while four-probe transport measurements indicate significant anisotropy in the conductivity ( σ ‖ σ hu ≈ 8 where ‖ denotes the extrusion direction). This anisotropy is nearly temperature independent. Electrically conductive fibres can also be prepared using Nomex or poly( p -phenylene-2,6-benzobisthiazole) (PBT) instead of Kevlar as the host polymer.

Electrically conductive, processable polymeric materials constructed from metallophthalocyanines

Abstract This contribution describes an approach to producing new classes of macromolecular/macromolecular and molecular/macromolecular hybrid materials which can be spun into environmentally stable, flexible, oriented, electrically conductive fibers. Solutions of a phthalocyanine-containing macromolecular ( e.g. , [Si(Pc)O] n ) or molecular( e.g. , Ni(Pc)) ‘metal’ precursor and a host polymer ( e.g. , Kevlar) are wet-spun to yield, after halogen or electrochemical doping, strong, air-stable fibers with thermally activated electronic conductivities as high as 5 ω −1 cm −1 . X-ray diffraction and resonance Raman studies of the fibers reveal the presence of preferentially oriented Kevlar and {[Si(Pc)O]I 1.1 } n (or M(Pc)I) crystalline regions, the latter regions with the metallophthalocyanine stacking directions preferentially parallel to the longitudinal fiber axis.

Electronic Properties of The Conductive Polymers [Si(Pc)O]xy)N With Different Doping Agents

Abstract Electrically conductive polymers have been prepared from the cofacially joined metallophthalocyanine polymer [Si(Pc)o]na Optical and electrical properties are investigated as a function of the type and degree of the incremental doping added to form the {[Si(Pc)o] Xy }n systems. The dopants are: X = BF4 PF6, SbF6 and I. In spite of the variation in structural and electronic characteristics of the doping agents, there is a considerable similarity in the behavior of the electronic transport.

Metallophthalocyanine Based Low-Dimensional Polymers and Related Molecular Compounds. Charge Transport and Electronic Structure Studies of A Metal-Free “Molecular Metal”

Abstract Single crystals of H2(Pc)I behave as a “molecular metal” with σRT ≈ 700 Ω−1cm−1 (σ‖/σ⊥ ≈ 500) and σmax ≈ 4000 Ω−1cm−1. The static magnetic susceptibility is Paulilike, and a Drude analysis of the optical reflectivity yields a tight-binding bandwidth of 0.77(7) eV.