Bismuth triple-decker phthalocyanine: synthesis and structure

Synthesis, Structure, and UV–Vis Characterization of Antimony(III) Phthalocyanine: [(SbPc)2(Sb2I8)(SbBr3)]2

A new antimony(III)–phthalocyanine complex with the formula of [(SbPc)2(Sb2I8)(SbBr3)]2 has been obtained in the reaction of pure antimony powder with phthalonitrile under the oxidation conditions by iodine monobromide vapors. The complex crystallizes in the centrosymmetric space group of the triclinic system. Both independent (SbPc)+ units exhibit non-planar conformation, since the Sb(III) is larger than the equilibrium cavity size of the ring and cannot be accommodated without its expansion; thus, the metal protrudes out of the cavity, forming a saucer shape. The centrosymmetric anionic unit of the crystal consists of two (Sb2I8)2− interacted anionic units forming (Sb4I16)4− anionic complex that interacts with two SbBr3 molecules to form [Sb6I16Br6]4− anionic aggregate. Each [Sb6I16Br6]4− anionic aggregate is surrounded by four (SbPc)+ cations forming a supramolecular centrosymmetric (SbPc)4[Sb6I16Br6] complex. Translationally related (SbPc)4[Sb6I16Br6] molecules form a stacking structure along the [100] and [011] directions with N4–N4 distances of 3.55 and 3.53 Å, respectively, between the back-to-back-oriented saucer-shaped (SbPc)+ units. The interaction between the building units of the crystal was analyzed using the Hirshfeld surface and the analysis of the 2D fingerprint plots. The UV–Vis absorption spectra of crystal 1 were taken in CH2Cl2 and toluene solutions in the concentration range from 10−5 to 10−6 mol/L. No significant changes related to aggregation in solutions were observed. The Q-band in toluene solution is red shifted by ~15 nm in comparison to that in CH2Cl2 solution. Oxidation of (SbPc)4[Sb6I16Br6] yields SbVPc derivative. Both SbIII and SbV phthalocyanine derivatives absorb near infrared light (600–900 nm), which should be intriguing from the point of view of potential use as photosensitizers for PDT and as an infrared cut filter for plasma display and silicon photodiodes.

Highly soluble tetrasubstituted lanthanide bis-phthalocyanines; synthesis, characterization, electrical properties and aggregation studies

We report the synthesis, characterization and electrical properties of lanthanide metal based bis-phthalocyanines, {M[Pc-(β-HHT)4]2} (HHT:1-hydroxyhexane-3-ylthio){ M [Formula: see text] Lu[Formula: see text] (2), Eu[Formula: see text] (3), and Yb[Formula: see text] (4)}. The interaction of bis-phthalocyanines with Ag[Formula: see text] and Pd[Formula: see text] metal ions were investigated by UV-vis spectroscopy and atomic force microscopy. Thin films of bis-phthalocyanine molecules were prepared by spin-coating method. The surface morphology of thin films were performed with Atomic Force Microscopy as further investigate. The electrical transport properties of ITO/Pc/Al devices were investigated. At low voltages all the films showed an ohmic conduction, whereas at higher voltage levels the conduction is dominated by space charged limited conduction with exponential distribution of trapping levels. Measurements of current density as a function of inverse temperature at constant applied voltage yielded a hole mobility values, μp[Formula: see text], [Formula: see text] and [Formula: see text] m2.sn[Formula: see text].V[Formula: see text] for lanthanium phthalocyanines. From the analysis of frequency, ω, dependence of electrical conductivity, σac. it was found that the [Formula: see text] obeys the power law given by σac = Aωs, in which the frequency exponent “s” decreases with temperature.

Synthesis, spectral and electrochemical properties of a novel phosphorous(V)-phthalocyanine

A novel phosphorous(V)-phthalocyanine, [ P ( tppc )( OH )( O )], where tppc denotes tetrakis{(2′,6′-dimethyl)phenoxy}phthalocyaninate, has been synthesized and its spectral properties in non-aqueous and aqueous media have been investigated. This compound has been found free from aggregation in EtOH whereas forms J-aggregates in CH 2 Cl 2 and acetonitrile, suggesting the presence of chemical interaction between the axial ligand and the surrounding solvent molecules. The most intense absorption band (Q-band) appears at 683 nm in EtOH , however, reaction with CF 3 COOH has given rise to a large red shift of the Q-band without lowering of its C 4 symmetry (evidenced by magnetic circular dichroism spectroscopy), indicating protonation at the axial site. Its fluorescence quantum yield has been determined (0.49 in EtOH ) and has been found much higher than those of the known Sb V or As V derivatives by more than one order of magnitude. The first reduction potential has been determined by cyclic voltammetry (-1.09 V vs. ferrocenium+/ferrocene) in CH 2 Cl 2. It is noteworthy that the Q-band maximum wavelength and the first reduction potential values are normal for conventional phthalocyanines despite the presence of pnictogen(V) in the cavity of the macrocyclic ligand.

Functional alcohol-soluble double-decker phthalocyanines: synthesis, characterization, electrochemistry and peripheral metal ion binding

In this study we report the preparation, physical characterization and electrochemistry of peripherally functionalized substituted ionophore double-decker lanthanide phthalocyanines, lanthanide bis-[(4,4″,4″,4‴)-tetrakis-(6-hydroxyhexylthio)phthalocyaninates], { M [ Pc ( S - C 6 H 13 OH )4]2} ( M = Pr III, Yb III, and Lu III). All benzenes on the double-decker phthalocyanines are functionalized with hydroxyhexylsulfanyl moieties for potential use as metal ion binding and surface anchors. The double-decker phthalocyanines synthesized from the anhydrous metal salts { Ln ( acac )3} and the corresponding 4-(6-hydroxyhexylthio)-1,2-dicyanobenzene exhibit ion-specific optical changes in the presence of Ag + and Pd 2+. Thio donors of the complexes coordinate to Ag + and Pd 2+ to give 4:1 metal-phthalocyanine complexes. Newly synthesized lanthanide double-decker phthalocyanines are soluble in methanol ( MeOH ), ethanol ( EtOH ), tetrahydrofuran ( THF ), dimethylformamide ( DMF ), dimethylsulfoxide ( DMSO ), chloronapthalene, quinoline and less soluble in i- PrOH and acetonitrile. Electrochemical studies reveal that all lanthanide-base complexes undergo ligand-based redox processes. The smaller HOMO-LUMO gaps of the complexes indicate the existence of strong π-orbital interactions between the rings of the sandwich. The newly synthesized compounds have been characterized by elemental analysis, FTIR, 1H and 13 C NMR, MS (ESI and Maldi-TOF), UV-vis and EPR spectral data.

Triple-decker cadmium phthalocyanine sandwich complexes: self-assembled EPR active complexes

The discovery and characterization of the first example of a bis-cadmiumtris-phthalocyanine triple-decker sandwich complex is reviewed. The compound, with each Pc ring substituted at the eight non-peripheral positions with hexyl chains, was obtained unexpectedly during recrystallization of the corresponding monomeric 1,4,8,11,15,18,22,25-octa-hexyl cadmium phthalocyanine from CH 2 Cl 2 and methanol. The scope for obtaining further examples of this new class of complex bearing different ring substituents is also described. A feature of the compounds is that they give an EPR signal. An electrochemical study has shown that the rest state of the core of the sandwich structure is a dianion arising from the imbalance of the charges on the two cadmium atoms and the three Pc 2- ligands. This is a spin 0 species. It is proposed that the free radical character arises because the potential for the first one-electron oxidation is unusually low for a phthalocyanine, allowing for the partial presence of the spin ½ species for non-peripherally substituted complexes and a more extensive presence of the EPR active redox state for peripherally substituted analogs. Results of chemical oxidation using iodine are also discussed. A spectroscopic and electrochemical study on the monomeric precursors revealed the mode of formation of the triple-decker complexes. It has been established that octa-alkyl cadmium phthalocyanines unexpectedly exist very predominantly as dimeric structures in CH 2 Cl 2 and these are proposed to be intermediates in the formation of the triple-decker complexes. Results from a series of cross experiments using differently substituted Pcs indicate that cadmium can be scrambled between a CdPc and a metal-free Pc . Furthermore, when either species is added to a solution of a triple-decker complex, the ligand from the added species becomes incorporated into new "mixed" triple-decker complexes. From these results it is proposed that the triple-decker structures are formed by self-assembly processes and that they can disassemble and reassemble in the solution phase. Preliminary measurements have identified ring substitution patterns that lead to higher oligomers.

Electrochemical and EPR studies of two substituted bis-cadmium tris-phthalocyanine complexes: elucidation of unexpectedly different free-radical character

The electronic and electron transfer behaviour of two examples of a recently discovered class of triple-decker sandwich complex based on three phthalocyanine ligands linked by two chelated cadmium ions has been investigated by EPR spectroscopy and cyclic voltammetry, square wave voltammetry and linear sweep voltammetry experiments. The two compounds, and , differ in the location of the eight alkyl groups attached to each of the phthalocyanine rings; at the non-peripheral sites in and the peripheral sites in . Quantitative comparison of the free radical character of and in solutions was undertaken by EPR spectroscopy and revealed that exists as a mixture of s = 0 and s = (1/2) species, whereas compound exists essentially as a spin (1/2) species alone. The electrochemical study of and was undertaken in both dichloromethane (CH(2)Cl(2)) and tetrahydrofuran (THF). The two compounds show comparable but subtly different redox behaviour which can only be attributed to the different locations of the substituents. Seventeen of the possible eighteen one-electron transfer processes could be identified for . The first oxidation wave for , both in THF and in CH(2)Cl(2) solutions, was encountered at ca. 160 mV lower potential than for implying that is much easier to initially oxidise than . This finding provides a rationale for the EPR results described above. In separate experiments, oxidation of and as solutions and spin-coated film formulations was achieved using iodine and was characterised by significant changes in the visible region absorption spectra of the compounds.

Electrochemical and spectroscopic detection of self-association of octa-alkyl phthalocyaninato cadmium compounds into dimeric species

The solution phase behaviour of non-peripherally substituted octa-hexyl cadmium phthalocyanine 3 and peripherally substituted octa-2-ethylhexyl cadmium phthalocyanine has been investigated in fresh solutions of CH(2)Cl(2), CHCl(3)-d(1) and THF/THF-d(8) using (1)H NMR spectrometry, UV-Vis spectroscopy, cyclic voltammetry, square wave voltammetry and linear sweep voltammetry. The compounds show an unexpected propensity to form dimeric species in CH(2)Cl(2) and CHCl(3)-d(1), and, in the case of , also to a lesser extent in THF/THF-d(8). This phenomenon is not observed for their metal-free analogues or . The electrochemical results provide particularly strong evidence for the dimeric structures. In particular both the first one-electron oxidation and one-electron reduction waves for 3 and 4, unlike those of and , are split. This is consistent with sequential oxidation/reduction of the two Pc ligands within a dimer. The dimeric species are likely to be the immediate precursors of the recently discovered bis-cadmium tris-phthalocyanine triple-decker sandwich complexes and formed from and over a period of time. The electrochemical data for compounds also show that (i) relative to the metal-free phthalocyanines, the cadmium phthalocyanines exhibit smaller formal reduction potentials for all but one of the observed electron transfer processes and (ii) the electron transfer processes associated with the peripherally substituted compounds, 2 and 4, are observed at more positive potentials than those for the corresponding non-peripherally substituted analogues 1 and 3.

Oligomeric Cadmium–Phthalocyanine Complexes: Novel Supramolecular Free Radical Structures

Certain cadmium-metallated phthalocyanines give rise to EPR active triple-decker sandwich complexes containing two Cd ions and three phthalocyanine (Pc) ligands. These have been shown to form when the ligands bear either eight non- peripheral alkyl or alkenyl substituents or eight peripheral 2-ethylhexyl groups. They can be derived either from three equivalents of a cadmium phthalocyanine precursor or from a 2:1 mixture of a cadmium phthalocyanine (CdPc) and a metal-free phthalocyanine (H(2)Pc). The mode of their formation has been investigated by a series of "cross" experiments. The results indicate that the triple-decker structures are formed by a self-assembly process. This is deduced from results that show that they can disassemble and reassemble with incorporation of differently substituted ligands derived from either an H(2)Pc or CdPc. The reassembled structures in these cross experiments can contain more than one ligand that originated from either the added CdPc or, and more surprisingly, the H(2)Pc compound. Mass spectrometry has also established that higher order oligomers can be formed when steric requirements between the alkyl substituents on adjacent rings in the stack are reduced. Thus an isotopic cluster for a Cd(5)Pc(6) complex has been observed when the eight peripheral substituents are hexyl chains and tetrameric complexes are formed when two different ligands are incorporated within a stack, with one carrying substituents at the peripheral sites and the other bearing substituents at the non-peripheral sites.

First example of a di-cadmium tris-phthalocyanine triple-decker sandwich complex

An unprecedented M(II)2Pc3 (M = Cd) triple-decker sandwich complex has been synthesized and characterised by single crystal X-ray crystallography; cyclic voltammetry shows an unusually large range of redox states and EPR spectroscopy indicates that the material exists in at least two redox states, one having spin (1/2).