Dinuclear and Tetranuclear Copper(II) Complexes with a Ligand Bearing Phthalocyanine and Schiff-Base Coordination Sites

Abstract

Dinuclear and tetranuclear copper(II) complexes with a ligand bearing phthalocyanine and Schiff-base coordination sites were prepared and characterized. The dinuclear complex has two copper(II) phthalocyanine units linked by 2,6-diiminomethyl-4-methylphenol. The imino nitrogen (Schiff-base) coordinates to two more copper(II) ions to give a tetranuclear copper(II) complex composed of a hydroxo- and phenoxo-bridged copper(II) dinuclear unit and two copper(II) phthalocyanine units. Magnetic, spectroscopic, and electrochemical studies showed that there is no significant interaction among the two copper(II) phthalocyanine units and the hydroxo- and phenoxo-bridged dinuclear unit.

Low Symmetry Phthalocyanines and Their Analogues

“…63,188,193,375,381,382 Subsequent reaction with a second type of precursor results in the selective formation of the AABB compound. their related structures have also been formed via the further modification of -NO 2 , 101,105,240,311,316 -NH 2 , 98,109,271,272,309 -ROH, 120,242,278,279,289,310,320,322,388 -CHO, 113,245,319 and -CN 94 substituents. In an unconventional approach to Pc synthesis, two recent papers have reported the use of electrophilic substitution reactions of unsubstituted D 4h symmetry metal phthalocyanines to enhance the solubility properties by introducing peripheral substituents.…”

“…399,400 MCD spectra have been reported for a wide range of low symmetry Pc's. 98,105,106,111,123,124,127,130,137,140,169,[186][187][188][189][190][191]195,201,247,248,295,296,311,367,368,372,373,375,[399][400][401][402] In the absence of a 4-fold axis of symmetry, these spectra are usually dominated by coupled pairs of oppositely signed Gaussian-shaped B 0 terms rather than first derivative-shaped A 1 terms due to the lifting of excited state degeneracies. 399,400 The optical spectra of Pc's and their analogues are usually described in terms of Gouterman's 4-orbital model 403 (Figure 6) and Michl's perimeter model 404,405 (Figure 7).…”

“…The optical spectra of directly fused Pc dimers contain a complex set of bands in the Q band region, with the most intense band red-shifted relative to that of the monomer (Figure 17), due to the effect of exciton coupling. [125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141] As is the case with radially symmetric phthalocyanines, significant issues can be faced with aggregation when the symmetry is lowered, which can make key spectroscopic measurements including the optical and NMR spectra extremely challenging. 413 Careful selection of peripheral substituents can help to alleviate this problem.…”

“…124,127,136,186,310,320,323,367,372,375 The few recent examples have often tended to focus primarily on the redox properties of the central metal. 124,186,375 Data have been obtained for the redox couples of a wide range of Pc's and their analogues based on the use of cyclic and differential pulse voltammetry (CV and DPV) 53,62,86,98,122,124,127,128,131,133,135,136,140,183,186,189,192,195,[201][202][203]205 ,209,219,219,245,261,267,268,273,274,277,278,284,298,305,306,310,316,318,329,350,367,375,381,401,402,418 and Osteryoung square-wave voltammetry. 96,111,122,219,251,277,305,306,383 In the absence of an open shell central metal, the trends in the optical and redox properties tend to mirror each other and often provide similar information.…”

“…π-systems (Figure 3). [125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141] This topic was reviewed relatively recently in the context of radially symmetric complexes. 142 Many of the approaches described can be readily applied to low symmetry Pc's and Pz's.…”