No abstract

No abstract

We have developed the synthesis of unsymmetrical metalloporphyrazines of the form M[pz(A:B 3 )], where A and B refer to two different types of peripheral functionality, and have used it to prepare new bi-and trimetallic solitaire-porphyrazines in which A represents a mono-or bimetallic moiety. The macrocyclic complexes described are based on the binucleating ligand, [M(norphthalocyanine-2,3-dithiolate)] 2-, [M(norpc)] 2-. This can be thought of as a metalloporphyrazine where B is a fused benzo ring; A represents two thiolates fused at the -pyrrole positions to form a dithiolene moiety that can bind a transition-metal ion in addition to one within the macrocyclic cavity. solitaire-Porphyrazines have been synthesized by chelation of [(L-L)M′] 2+ to the [M(norpc)] 2-ligand where M ) "2H", Ni, Cu, or Mn-Cl, L-L is a bis(diphosphino) or bis(diamino) group and M′ ) Ni, Pd, or Pt. Crystal structures have been obtained for 11b, where the [H 2 (norpc)] 2-ligand coordinates the diphosphinopalladium moiety, [Pd-(dppf)] 2+ , by the two thiolate sulfur atoms at its periphery, and for 11h, with the diaminoplatinum moiety, [Pt-(teeda)] 2+ , bound to the periphery of the [Ni(norpc)] 2-ligand.In crystals of 11b and 11h, the molecules appear as face-to-face dimers. However, the dimer of 11b and the two crystallographically independent dimers of 11h each shows a distinctly different degree of overlap. The electronic absorption spectra of a series of porphyrazines in which the two peripheral sulfur atoms form thioether moieties with a modified benzyl-protecting group (6-10) show that the peripheral asymmetry of the macrocyclic framework causes a strong splitting of the (π-π*) Q-band. In contrast, when the peripheral sulfurs bind a metal ion to form solitaire-porphyrazines 11a-h, the optical spectra closely resemble that of the symmetrical pc, with unsplit Q band. The EPR spectrum of solitaire 11d, where M ) Cu, L-L ) a bis(diphosphino) cap, M′ ) Pd, has features consistent with other square-planar copper(II) porphyrins and phthalocyanines. Cyclic voltammograms of compound 11b shows two reversible ring reductions at potentials similar to those of H 2 (pc) as well as a reversible oxidation associated with the ferrocene portion of the Pd(dppf) moiety.

Peripherally-functionalized porphyrazines of the form M[pz(A n :B4-n )] (inset 1), where A and B symbolize functional moieties (e.g., a−d in Table ) fused directly to the β-positions of the pyrroles, have the potential to serve in a wide range of applications. Previously, we reported the synthesis of porphyrazinedi- and octathiolate ligands, M[pz(b3:c1)] and M[pz(c4)], respectively, where b is a fused benzo ring and c represents two thiolates fused at the β-pyrrole positions to form a dithiolene capable of the peripheral chelation of a metal ion. We describe here a general strategy that solves the more difficult problem of preparing and isolating the porphyrazinetetra- and hexathioethers and the porphyrazinetetra- and hexathiolates, with the focus being the trinuclear metal complexes of the trans- and cis-porphyrazinetetrathiolate isomers (trans- and cis-M[pz(b2:d2)]), denoted as gemini porphyrazines. Spectroscopic and electrochemical studies reveal that the physical properties of the cis- and trans-tetrathioether porphyrazines exhibit intriguing differences associated with their distinct molecular symmetries. These functionalized macrocycles have been used to prepare the trans- and cis-gemini porphyrazines 14 and 16, the two isomeric porphyrazinetetrathiolate macrocycles that are peripherally-metalated with two bis(triethylphosphine)platinum(II) moieties. The X-ray structure of the trans isomer, 14, is presented; it is the first structure of a porphyrazine or phthalocyanine having a trans-type substitution pattern.

The preparation of a bis-copper(II) complex of an expanded porphyrin is described. A single-crystal X-ray structural analysis of this complex showed the two metal centers to lie within the mean plane of the macrocycle with a rather short interatomic distance of 2.761(1) Å. The two metal centers are formally in the +2 oxidation state and are weakly antiferromagnetically coupled. The overall complex is thus dianionic.

We describe the complete synthesis and characterization of a new family of peripherally functionalized porphyrazines (pz's) with four, three, or two (in a trans conformation) bis[thioethoxy(ethoxy)ethanol] moieties appended at the pyrroles. These "polyetherol" groups serve as weak exocyclic binding sites for a number of metal ions and also provide solubility of the pz's in low molecular-weight alcohols and water. Electronic spectra of the modified porphyrazines exhibit distinct changes in the visible region (both absorbance and fluorescence) in response to treatment with Ag+, Pb2+, Cd2+, Cs+, and Ni2+ in solution. Such properties make these compounds intriguing candidates for incorporation into the transducer layers in optically based chemical sensors.

No abstract

No abstract