Tetra-2,3-pyrazinoporphyrazines with Externally Appended Pyridine Rings. 2. Metal Complexes of Tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazine:  Linear and Nonlinear Optical Properties and Electrochemical Behavior

Abstract

A series of metal complexes of tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazine, [Py(8)TPyzPzH(2)], having the general formula [Py(8)TPyzPzM].xH(2)O (M = Mg(II)(H(2)O), Mn(II), Co(II), Cu(II), Zn(II); x = 3-8) were synthesized by reaction of the free-base macrocycle with the appropriate metal acetate in pyridine or dimethyl sulfoxide under mild conditions. Clathrated water and retained pyridine molecules for the Mn(II) and Co(II) species are easily eliminated by heating under vacuum, the water molecules being recovered by exposure of the unsolvated macrocycles to air. Magnetic susceptibility measurements and EPR spectra of the materials in the solid state provide basic information on the spin state of the Cu(II), Co(II), and Mn(II) species. Colloidal solutions caused by molecular aggregation are formed in nondonor solvents (CH(2)Cl(2), CHCl(3)), a moderately basic solvent (pyridine), and an acidic solvent (CH(3)COOH), with the extent of aggregation depending on the specific solvent and the central metal ion. UV-vis spectral monitoring of the solutions after preparation indicates that disaggregation systematically occurs as a function of time leading ultimately to the formation of clear solutions containing the monomeric form of the porphyrazine. Cyclic voltammetry and thin-layer spectroelectrochemistry show that each compound with an electroinactive metal ion undergoes four reversible one-electron reductions, leading to formation of the negatively charged species [Py(8)TPyzPzM](n-) (n = 1 - 4). The stepwise uptake of four electrons is consistent with a ring-centered reduction, but in the case of the cobalt complex a metal-centered (Co(II) --> Co(I)) reduction occurs in the first process and only three additional reductions are observed. No oxidations are observed in pyridine or CH(2)Cl(2) containing 0.1 M tetrabuthylammonium perchlorate (TBAP). The nonlinear optical properties (NLO) of the species [Py(8)TPyzPzM] (M = 2H(I), Cu(II), Zn(II), Mg(II)(H(2)O)) have also been examined with nanosecond pulses at 532 nm in dimethyl sulfoxide solution. Reverse saturable absorption is shown by all of the [Py(8)TPyzPzM] species, which exhibit distinct behavior depending on the nature of M and extent of aggregation.

Tetrapyrazinoporphyrazines with different number of peripheral pyridyl rings: Synthesis, photophysical and photochemical properties

“…Tetrapyrazinoporphyrazines (TPyzPA) with eight pyridyl moieties have been investigated for their remarkable electron-deficient properties in electrochemistry both free and quarternized which allowed water solubility [9][10][11][12]. The same compounds have also been investigated for their non-linear optical properties [13].…”

Synthesis and EPR studies of vanadyl tetrakis(selenodiazole)porphyrazine

“…The annulated 1,2,5-selenodiazole rings in the porphyrazine macrocycle, which can easily undergo different transformations [10][11][12][13][14][15][16][17], open up a new synthetic approach to octaaminoporphyrazines. The metalation of free-base porphyrazine cores with metals such as Co(II), Ni(II), Zn(II), etc.…”

Azaphthalocyanines with extended conjugation through heteroaryl and aryl substituents: Photochemical and photophysical properties

“…In all the literature sources, only synthesis is the objective of research [9,10] of heteroaromatically substituted AzaPc, or the derivatives are investigated from the point of view of electrochemistry [11]. To the best of our knowledge, no investigations on the properties important for PDT have been carried out for the compounds involved in this study.…”