Synthesis of high-purity phthalocyanines (pc): High intrinsic conductivities in the molecular conductors H[sub 2](pc)I and Ni(pc)I
- Northwestern Univ., Evanston, IL (United States)
The authors show that one can prepare M(pc)I crystals, M = [open quotes]H[sub 2][close quotes] and Ni, with remarkably improved charge-transport properties by carefully avoiding impurities in the preparation of the M(pc) precursors. The purest H[sub 2](pc) (<60 ppm free-radical impurities) was prepared by a melt method in quartz and Teflon vessels while very pure Ni(pc) (170-250 pm) could only be obtained by metalation of the pure H[sub 2](pc). Template syntheses of Ni(pc) result in impure material and are to be discouraged for applications requiring very pure M(pc) materials. H[sub 2](pc)I and Ni(pc)I synthesized from the high-purity precursors remain metallic down to ca. 3 K, a far lower temperature than ever before observed. At this temperature the conductivities exhibit maximum values that are ca. 30-fold greater than at room temperature, not 5-7-fold as seen before, with absolute values of [sigma] [approximately] (1-2) [times] 10[sup 4] [Omega][sup [minus]1] cm[sup [minus]1]. The study of a series of Ni(pc)I compounds prepared from Ni(pc) parent materials exhibiting a range of purity levels further shows a strong correlation between the charge-transport properties and the level of paramagnetic impurities in the macrocycle precursor. However, the maximum conductivity appears to saturate at the lowest impurity concentrations, which suggests that the behavior exhibited by the best materials prepared are representative for the first time of the limiting, intrinsic charge-transport properties of H[sub 2](pc)I and Ni(pc)I. A full structure report for H[sub 2](pc)I-1 is presented also. The structure consists of metal-over-metal stacks of partially oxidized H[sub 2](pc) groups surrounded by linear chains of triiodide anions. H[sub 2](pc)I crystallizes with two formula units in the tetragonal space group D[sub 4h][sup 2]-P4/mcc with a = 13.931 [angstrom], c = 6.411 [angstrom], and V = 1244.2 [angstrom][sup 3] (T = 108 K).
- OSTI ID:
- 5035875
- Journal Information:
- Inorganic Chemistry; (United States), Vol. 32:16; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
HYDROGEN COMPLEXES
CHEMICAL PREPARATION
NICKEL COMPLEXES
PHTHALOCYANINES
ELECTRIC CONDUCTIVITY
IMPURITIES
LATTICE PARAMETERS
RADICALS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TETRAGONAL LATTICES
COMPLEXES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DYES
ELECTRICAL PROPERTIES
HETEROCYCLIC COMPOUNDS
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
SYNTHESIS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
360602 - Other Materials- Structure & Phase Studies
360606 - Other Materials- Physical Properties- (1992-)