Synthesis, Electronic Spectroscopy, Cyclic Voltammetry, Photophysics, Electrical Properties and X‐ray Molecular Structures of meso‐{Tetrakis[4‐(benzoyloxy)phenyl]porphyrinato}zinc(II) Complexes with Aza Ligands

Abstract

The synthesis of the new meso-porphyrin tetrakis-[4-(benzoyloxy)phenyl]porphyrin (H 2 TPBP), the meso-{tetrakis-[4-(benzoyloxy)phenyl]porphyrinato}zinc(II) starting material [Zn(TPBP)] (1), and the 1,4-diazabicyclo[2.2.2]octane (dabco), pyrazine (pyz), 4,4′-bipyridine (4,4′-bpy), 4,4′-diaminodiphenylmethane (4,4′-mda), and 4-cyanopyridine (4-CNpy) coordination compounds with [Zn(TPBP)] (2-7) are described. The preparation of the dabco derivative in chlorobenzene leads to a crystalline monomeric five-coordinate zinc porphyrin species (2), whereas the synthesis in dichloromethane gives a five-coordinate zinc metalloporphyrin dimer (3) in the solid state. The pyrazine derivative crystallizes as a bis-pyrazine six-coordinate zinc metalloporphyrin (4). Complex 5 in the solid state is a dimer with 4,4′-bpy as a bridging ligand, whereas the 4,4′-mda species (6) is a five-coordinated monomeric zinc derivative in [a] 5004 Scheme 1. Schematic representations of the different coordination types for zinc porphyrins with bidentate N-donor ligands (L). Scheme 2. Bidentate N-donor ligands (aza ligands) used in this work.

Development of iridium porphyrin arrays by axial coordination through N-bidentate ligand: Synthesis and evaluation of the optical, electrochemical and thermal properties

“…The high correlation amongst the calculated and measured m/z values of each fragments peaks allows to confirm the axial coordination of two bipyridine molecules to the iridium metal center on the porphyrin cavity. These results are in agreement with the structure identified by 1 H NMR, where the upfield shifting proton resonances of ligand may be due to the shielding effect caused by the porphyrin ring current and indicate of metalloporphyrin selfassembly [16,22,33].…”

“…The success of this reaction was evidenced essentially by the wavenumber corresponding to the stretching of the C-N and C-C bonds, of the bipyridine moiety, around 1593, 1470 and 1407 cm À1 , and the absence of the band of CO at 2045 cm À1 [16,29]. The axial coordination of aza conjugated ligands, as bipyridine, has influence on the complexes vibrational waves, where the C@C stretch either on phenyl and porphyrin, the C-H bend in the phenyl and the C-N stretch in porphyrin are shifted to lower or higher energies [16,34]. The absence of a vibrational band at around 3300 cm À1 , typical of N-H vibrations, indicates that no demetallation occurred, which prove the stability of the metal complex.…”

“…The coordination of metal ions by porphyrins' ring core and axial conjugated ligands is a useful strategy in the construction of multicomponent metalloporphyrin-based molecular complexes, which can be very versatile for the preparation of building block polymers with interesting properties. Metalloporphyrins arrays have, lately, attracted high interest as a new class of porphyrinbased polymers with a wide range of applications, including catalysis, molecular sensors, electronics and new photonics materials, nonlinear optics, electrochromic and transport energy charge, biological and others [6,7,[14][15][16]. Electronic and electrical conductive properties are the most important characteristics of materials for such applications, thus they should be taken into account when develop novel metalloporphyrins systems.…”

Effect of the coordination of π-acceptor 4-cyanopyridine ligand on the structural and electronic properties ofmeso-tetra(para-methoxy) andmeso-tetra(para-chlorophenyl) porphyrin cobalt(ii) coordination compounds. Application in the catalytic degradation of methylene blue dye

“…The coordination of the 4-CNpy to the cobalt in complexes 1-2 is conrmed by the absorption bands at 2237 and 2234 cm À1 respectively corresponding to the n(C^N) stretching frequency which are slightly below that of the free 4-cyanopyridine compound (2243 cm À1 ) indicating that this axial ligand is coordinated to the Co(II) center metal through the pyridyl group and not the nitrile moiety. 5 The proton NMR spectroscopy is a very convenient technique to determine if a cobalt metalloporphyrin is a diamagnetic cobalt(III) complex or a paramagnetic cobalt(II) coordination compound with the 3d 6 and 3d 7 ground state electronic congurations of the Co(III) and the Co(II) cations, respectively. 20 For cobalt(III) meso-porphyrin derivatives, the b-pyrrolic and the phenyl ring protons are slightly shied compared to those of the corresponding free base porphyrins with a chemical shi values in the range [8.5; 9] ppm and between 8.5 and 7.5 ppm for the phenyl protons (Table 1).…”

“…The spectroscopic, structural, magnetic and electrochemical properties of metalloporphyrins involving several metal ions such as Fe(II), Fe(III), Zn(II), Cd(II), Sn(IV), Mg(II), Mn(III) and Co(II) have been investigated by our group for more than two decades. [1][2][3][4][5][6][7] The study of these tetrapyrrolic coordination compounds is of great importance because they provide good models for understanding the structural, electronic and magnetic properties of hemoproteins and heme-like enzymes such as cytochromes P450. Recently, porphyrins and porphyrin related compounds are nding crucial use in new applications such as catalysis in solar photovoltaic cells, [8][9][10] as chemical sensors 11,12 and as photosensitizing agents (PS) for photodynamic therapy (PDT).…”