Interfacial Molecular Assemblies of Metalloporphyrins with Two Trans or One Axial Ligands

Abstract

Molecular assemblies of metalloporphyrins trans-dichloro(5,10,15,20-tetra-p-tolylporphyrinato)tin(IV) (SnCl2TPPMe) and trans-dihydroxo(5,10,15,20-tetra-p-tolylporphyrinato)tin(IV) (Sn(OH)2TPPMe), which have two trans axial ligands, as well 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine iron(III) chloride (FeClTPPOMe) and 5,10,15,20-tetraphenyl-21H,23H-porphine manganese(III) chloride (MnClTPP), which have one axial ligand, are interfacially organized by Langmuir and Langmuir-Blodgett (LB) techniques. SnCl2TPPMe and Sn(OH)2TPPMe form nanofibrous structures which can display distinct supramolecular chirality, although the molecular units themselves are achiral, while FeClTPPOMe and MnClTPP form irregular nanoparticles that display negligible supramolecular chirality. An interpretation in terms of the effects of the axial ligands is proposed for this interesting phenomenon. Moreover, compared with assemblies of the diprotonated free-base porphyrins, which are fabricated by interfacial (air/2.4 M HCl) organization of free-base porphyrin, those of SnCl2TPPMe and Sn(OH)2TPPMe display higher stability in terms of supramolecular chirality. These results indicate that the assembly properties of metalloporphyrins can essentially be affected by the axial ligands that are attached to their chromophores, and that stable chiral porphyrin supramolecular associations can be easily produced by using achiral metalloporphyrins bearing two trans axial ligands.

Porphyrin Nanoassemblies via Surfactant-Assisted Assembly and Single Nanofiber Nanoelectronic Sensors for High-Performance H2O2 Vapor Sensing

“…Consequently, there might exist various aggregation styles in the assemblies, namely, face-to-face, back-to-back, and face-to-back configurations. 46 We tentatively suggest that these multiple packing configurations might be related to the observations that two kinds of J-like aggregates (namely, with or without an interplanar staggering angle) are formed in the formulated nanostructures. We, however, have to stress that a detailed understanding concerning this issue is still unclear at the present stage.…”

“…Different from ZnTPyP, there is an axial oxygen ligand anchored on the macrocycle of TiOTPyP, endowing it with a pyramidal geometry. Consequently, there might exist various aggregation styles in the assemblies, namely, face-to-face, back-to-back, and face-to-back configurations . We tentatively suggest that these multiple packing configurations might be related to the observations that two kinds of J-like aggregates (namely, with or without an interplanar staggering angle) are formed in the formulated nanostructures.…”

“…Consequently, the SDBS–H2TPyP interactions might be at a disadvantage status in the competition such that the strong H2TPyP–H2TPyP interactions dominate the assembly, facilitating the formation of irregular nanospecies. In contrast, compared to their counterparts of free-base porphyrins, Zn stands out of the porphyrin plane in zinc porphyrins. , This would lead to some changes in charge distribution and at the same time bring about steric hindrance between ZnTPyP molecules, thus weakening the porphyrin–porphyrin intermolecular interactions. ,, Accordingly, different from the case of H2TPyP, the role played by the SDBS–ZnTPyP interactions during the SAS of ZnTPyP could not be neglected. The result is that ZnTPyP/surfactant complexes, which are mainly driven by the hydrophobic interactions ,− ,, and π–π interactions between surfactant and ZnTPyP, are formed upon the meeting of ZnTPyP and SDBS in the oil (chloroform)-in-water medium.…”

“…Generally, free-base porphyrins have a nice planarity, ,,− favoring the intermolecular porphyrin–porphyrin interactions. Consequently, the SDBS–H2TPyP interactions might be at a disadvantage status in the competition such that the strong H2TPyP–H2TPyP interactions dominate the assembly, facilitating the formation of irregular nanospecies.…”

“…44,45 This would lead to some changes in charge distribution and at the same time bring about steric hindrance between ZnTPyP molecules, 45 thus weakening the porphyrinÀporphyrin intermolecular interactions. 36,38,46 Accordingly, different from the case of H2TPyP, the role played by the SDBSÀZnTPyP interactions during the SAS of ZnTPyP could not be neglected. The result is that ZnTPyP/surfactant complexes, which are mainly driven by the hydrophobic interactions 19,41À43,47,48 and πÀπ interactions 30 between surfactant and ZnTPyP, are formed upon the meeting of ZnTPyP and SDBS in the oil (chloroform)-in-water medium.…”