Multicomponent Porphyrin‐Based Tetragonal Prismatic Metallacages and their Photophysical Properties

Abstract

Multicomponent coordination‐driven self‐assembly has proved to be a convenient approach to prepare advanced supramolecular coordination complexes (SCCs), especially for those with three‐dimensional structures. Herein, we report the preparation of three tetragonal prismatic cages via the self‐assembly of Pt(PEt3)2(OTf)2, three different linear dipyridyl ligands and porphyrin‐based sodium benzoate ligands. Due to the efficient charge separation in the coordination process of Pt(PEt3)2(OTf)2 with pyridine and carboxylic acid and the directionality of metal‐coordination bonds, these cages were prepared in high isolated yields (more than 90 %). The absorption and emission properties as well as the singlet oxygen quantum yields of these cages were also studied, showing their potential applications as contrast agents for bio‐imaging and photosensitizers for photodynamic therapy.

Pt(ii)-coordinated tricomponent self-assemblies of tetrapyridyl porphyrin and dicarboxylate ligands: are they 3D prisms or 2D bow-ties?

“…Interestingly, the previously reported 30 ESI-MS profile of a tricomponent SCC featuring (Et 3 P) 2 Pt II , H 2 TPP, and BDC revealed a prominent m / z peak at 1481.38, which possibly represented the [M-2PF 6 − ] 2+ species of the bow-tie complex [{(Et 3 P) 2 Pt} 4 (H 2 TPP)(BDC) 2 ] 4+ ·4(PF 6 − ). Although previous reports have assigned certain m / z peaks to [{(Et 3 P) 2 Pt} 8 (M′TPP) 2 (XDC) 4 ] 8+ ·8(X − ) prisms, 30,33,34,56,64 in light of our extensive X-ray crystallographic and NMR analyses, those peaks could be attributed to dimers of [{(Et 3 P) 2 Pt} 4 (M′TPP) (XDC) 2 ] 4+ ·4(X − ) bow-tie complexes (after the loss of certain counterions) instead of any prisms. Thus, in light of the discovery of M′TPP-based tricomponent bow-tie complexes and a better understanding of why the corresponding tetragonal prisms were not formed, it appears that careful 2D NMR and X-ray crystallographic studies are vital for accurate structural characterization of similar tricomponent SCCs.…”

“…The ZnTPP-based BT1-BT4 and H 2 TPP-based BT2 0 , BT3 0 , and BT4 0 displayed the respective [M-2TfO] 2+ peaks at m/z ¼ 1497.09, 1593. 58 ] 8+ $8(X À ) prisms, 30,33,34,56,64 in light of our extensive X-ray crystallographic and NMR analyses, those peaks could be attributed to dimers of [{(Et 3 P) 2 -Pt} 4 (M 0 TPP) (XDC) 2 ] 4+ $4(X À ) bow-tie complexes (aer the loss of certain counterions) instead of any prisms. Thus, in light of the discovery of M 0 TPP-based tricomponent bow-tie complexes and a better understanding of why the corresponding tetragonal prisms were not formed, it appears that careful 2D NMR and Xray crystallographic studies are vital for accurate structural characterization of similar tricomponent SCCs.…”

Pt(II)-Coordinated Tricomponent Self-Assemblies of Tetrapyridyl Porphyrin and Dicarboxylate Ligands: Are They 3D Prisms or 2D Bow Ties?

“…Et3P)2Pt}4(H2TPP)(BDC)2] 4+ •4(PF6 -) but was overlooked previously. Since none of the previously reported M¢TPP-based tricomponent SCCs displayed the expected 1 H NMR spectra that could have supported the proposed prism formation (vide supra),30,33,34,56,57 and our extensive 2D NMR and ESI-MS data discussed above as well as the single-crystal structures presented below unequivocally demonstrated the formation of bow tie complexes instead of any prisms, it is plausible that the m/z peaks that were previously ascribed to 8:2:4 [{(Et3P)2Pt}8(M¢TPP)2(XDC)4] 8+ •8(X -) prisms, were actually associated with the dimers of 4:1:2 [{(Et3P)2Pt}4(M¢TPP)(XDC)2] 4+ •4(X -) bow tie complexes (after loss of some counterions) instead of the proposed prisms. Alternatively, the bow tie complexes could have reorganized into prisms under certain electrospray ionization conditions, giving a false impression about the proposed prisms formation, which was not otherwise supported by any other experimental data.…”

Pt(II)-Coordinated Tricomponent Self-Assemblies of Tetrapyridyl Porphyrin and Dicarboxylate Ligands: Are They 3D Prisms or 2D Bow Ties?

“…Et3P)2Pt}4(H2TPP)(BDC)2] 4+ •4(PF6 -) but was overlooked previously. Since none of the previously reported M¢TPP-based tricomponent SCCs displayed the expected 1 H NMR spectra that could have supported the proposed prism formation (vide supra),30,33,34,56,57 and our extensive 2D NMR and ESI-MS data discussed above as well as the single-crystal structures presented below unequivocally demonstrated the formation of bow tie complexes instead of any prisms, it is plausible that the m/z peaks that were previously ascribed to 8:2:4 [{(Et3P)2Pt}8(M¢TPP)2(XDC)4] 8+ •8(X -) prisms, were actually associated with the dimers of 4:1:2 [{(Et3P)2Pt}4(M¢TPP)(XDC)2] 4+ •4(X -) bow tie complexes (after loss of some counterions) instead of the proposed prisms. Alternatively, the bow tie complexes could have reorganized into prisms under certain electrospray ionization conditions, giving a false impression about the proposed prisms formation, which was not otherwise supported by any other experimental data.Single-Crystal Structures of Bow TieComplexes.…”