Spectroscopic and redox properties of alkyl-substituted lutetium diphthalocyanines in dichloromethane

Lu(iii) bis-phthalocyanines containing carbazole moieties: synthesis, characterization, electrochemical properties and sensor applications

In this study, the synthesis and characterization of sandwich type Lu(iii) bis-phthalocyanines bearing electropolymerizable carbazole groups were evaluated and their electrochemical sensing properties studied towards DA, UA and AA.

Electronic structures and spectral properties of double- and triple-decker phthalocyanine complexes in a localized molecular orbital view

This paper reviews the studies on the electronic structures and spectroscopic properties of sandwich-type complexes M ( Pc )2 and M 2( Pc )3. The subjects discussed are as follows. (1) Electronic spectra of closed-shell Pc dimers and trimers. The complexes with closed-shell systems, such as [ Lu ( Pc )2]−, Sn ( Pc )2 and Lu 2( Pc )3, can be thought of as stacked systems composed only of Pc 2−. The excited states of these complexes can be described by locally excited and charge transfer configurations. The coupling terms of the configurations are written using orbitals localized on each Pc ring. Assignments of the observed absorption bands are discussed. Computational studies on the band assignments were carried out using a localized molecular orbital (LO) basis which maximizes orbital populations on one of the Pc rings. (2) Electronic structures of πelectron-deficient Pc dimers and trimers. Oxidation of [ Lu ( Pc )2]− or Lu 2( Pc )3 yields systems with π-electron deficiency or π-hole(s) residing on multiple Pc sites. The delocalized nature of the π-hole in Lu ( Pc )2 is elucidated by comparison of the electronic spectra of symmetric and asymmetric dimers composed of Pc and Nc ( H 2 Nc ≡ naphthalocyanine ). The band assignments of the dimer radicals are discussed. The Pc trimer radical shows an intense absorption band at about 5000 cm−1, which is 2000 cm−1 lower than the valence resonance band of Lu ( Pc )2. The two-electron-deficient complexes [ Lu ( Pc )2]+ and [ Lu 2( Pc )3]2+ also show intense near-IR bands at higher energy than the corresponding monoradical species. The interactions that determine the excitation energies of the near-IR bands of the π-electron-deficient species are elucidated.

Axially Polarized NIR Absorption Bands in Electron-deficient Lanthanide Phthalocyanine Dimers and Trimers

Absorption and MCD spectra of the two-electron oxidized lutetium phthalocyanine trimer [( Pc ) Lu ( CRPc ) Lu ( Pc )]2+ ( Pc ≡ phthalocyanine ; CRPc ≡ 15- crown -5- substituted Pc ) as well as the MCD spectrum of the oxidized lutetium Pc dimer [ Lu ( Pc )2]+ are reported. These ‘two-electron-deficient’ Pc stacks show absorption bands in the NIR region whose intensities are comparable with those of the Q bands. The band of [ Lu ( Pc )2]+ showed only an MCD B term with no A term contribution, from which we assign the band to a non-degenerate transition whose transition moments are perpendicular to the Pc planes. In both trimer and dimer cases the excitation energy is higher than that of the corresponding NIR band in the ‘one-electron-deficient’ Pc stack [( Pc ) Lu ( CRPc ) Lu ( Pc )]+ or [ Lu ( Pc )2], but the magnitudes of the shift were significantly different (1500 cm−1 in the trimer and 4500 cm−1 in the dimer). The energy shifts are shown to be represented by a pair of two-electron repulsion integrals in a localized orbital basis. The model reproduced well the direction and magnitude of the shifts using numerical values of the integrals.

Electrochemical and spectroscopic investigation of neutral, oxidized and reduced double-decker lutetium(III) phthalocyanines

The double-decker lutetium(III) phthalocyanine [( C 6 H 13 S )8 Pc ]2 Lu was investigated by electrochemical and spectroelectrochemical methods and comparisons made to previously investigated [( C 12 H 25 S )4 Pc ]2 Lu and ( Pc )2 Lu under the some experimental conditions. All three compounds undergo a single reversible one-electron oxidation and up to four reversible one-electron reductions in CH 2 Cl 2 containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). The octa- and tetra substituted phthalocyanine derivatives exhibit one oxidation and three or four reductions in solution while five reductions can be detected for the two compounds in a gel-like cast film membrane of tetraoctylphosphonium bromide (4 C 8 P + Br −) at a basal plane pyrolytic graphite electrode which was immersed in aqueous 0.5 M KCl . The half-wave potentials of these SR substituted complexes in CH 2 Cl 2 are negatively shifted by 210-490 mV from E1/2 values for the same compounds in the aqueous 4 C 8P+ Br − matrix and five reductions of these compounds are observed under the latter experimental conditions. The UV-visible spectra of the compounds were measured in five different oxidation states and ESR spectra were also characterized for the neutral and doubly reduced complexes. As was expected, [( Pc )2 Lu ]−,{[( C 6 H 13 S )8 Pc ]2 Lu }− and {[( C 12 H 25 S )4 Pc ]2 Lu }− are ESR silent while electrogenerated [( Pc )2 Lu ]2−, {[( C 6 H 13 S )8 Pc ]2 Lu }2− and {[( C 12 H 25 S )4 Pc ]2 Lu }2− show broad strong signals at g = 2.0046, 2.0041 and 2.0034 with linewidths of 13.9, 16.1 and 12.9, respectively. These signals are indicative of organic free radicals where the unpaired electrons of the dianion are delocalized over two macrocycles.

Synthesis, characterization and EPR spectroscopy of novel s-triazines bearing three oxygen-linked phthalocyanines

Compound 1 (2,4,6-tris(2-oxaphthalonitrile)- s -triazine) has been prepared by the reaction of 4-nitrophthalonitrile and cyanuric acid in dry DMF as the solvent in the presence of K 2 CO 3 as the base. An interesting s -triazine, containing three oxa metal phthalocyanines ( M = Zn , Co or Cu ) has been synthesized from compound 1, 4,5-bis(hexylthio)phthalonitrile and the corresponding anhydrous metal salts ( Zn ( OAc )2, CoCl 2 or CuCl ) by the method of statistically mixed condensation. The new compounds and phthalocyanines were obtained in sufficient purity after successive washings with different solvents and were characterized by elemental analysis, UV-vis, IR, NMR and EPR spectroscopy.

Synthesis, structure, spectroscopic properties, and magnetic properties of an octakis(alkylthio)-substituted lutetium(III) bisphthalocyanine

The synthesis of a new sandwich lutetium(III) bisphthalocyanine substituted with hexylthio groups (1), [(C6H1)S)8-Pc]2Lu, is described. The compound is very soluble in most common organic solvents and has been fully characterized (elemental analysis, IR, 1H and 13C NMR, UV-vis spectroscopy, mass spectrometry). The chemically oxidized and reduced forms have been formed and characterized. The crystal structure of the compound (1) has been determined by X-ray diffraction on a single crystal. It crystallizes in the monoclinic space group C2/c with a = 31.558(2) A, b = 32.755(2) A, c = 20.489(1) A, beta = 127.119(1) degrees, and Z = 4. The temperature dependence of the magnetic susceptibility, measured on polycrystalline samples and in the range 6-300 K, is in agreement with one unpaired electron per molecular unit as found for the unsubstituted derivative. The magnetic results can be modeled assuming one-dimensional chain of spin S = 1/2 with g = 2.04 and an antiferromagnetic coupling (J = -11.83 cm(-1), H = -2JSigmaSiSj).

From the Single- to the Triple-Decker Sandwich. Effect of Stacking on the Redox and UV-Visible Spectroscopic Properties of Lutetium(III) 1,2-Naphthalocyaninate Complexes

(1,2-Naphthalocyaninato)lutetium(III), bis(1,2-naphthalocyaninato)lutetium(III), and tris(1,2-naphthalocyaninato)dilutetium(III) have been synthesized in good yields. These complexes were characterized by UV-visible, (1)H NMR, and mass spectroscopies and by electrochemical techniques. Bis(1,2-naphthalocyaninato)lutetium(III) is compared to bis(2,3-naphthalocyaninato)lutetium(III): the good correspondance between the experimental data and theoretical results obtained by others is emphasized in this work. Stacking one to three macrocyclic rings is possible in the series of the 1,2-naphthalocyanine sandwich-like complexes with lutetium(III); as shown by UV-visible spectroelectrochemistry and voltammetry, this influences greatly the pi-conjugated systems, modifying spectacularly their spectroscopic and redox properties.