Synthesis and Properties of Porphyrin Nanotubes

Abstract

Discrete π‐conjugated zinc porphyrin nanotubes are investigated as molecular analogues of carbon nanotubes. These porphyrin nanotubes have a diameter of 2.4 nm (Zn–Zn distance) and lengths of up to 3.6 nm, measured to the van der Waals surfaces of the outer β‐pyrrole hydrogen atoms, or 4.5 nm measured to the para hydrogen atoms of the aryl groups. We explore three different strategies for synthesizing these nanotubes. The first two strategies use a template to achieve direct or sequential stave‐joining, respectively, and proceed via linear oligomers that pre‐define the length of the nanotube. These strategies are applied to synthesize porphyrin nanotubes containing 12‐ or 18‐porphyrin subunits, with ethynylene (C2) or butadiynylene (C4) links between the 6‐porphyrin nanorings. The third strategy involves the covalent stacking of pre‐formed 6‐porphyrin nanorings to form a 12‐porphyrin nanotube, without using a template to guide this coupling reaction. The nanotubes show strongly red‐shifted absorption spectra and low fluorescence quantum yields, indicating structural rigidity and extensive π‐conjugation.

Carbon Nanotubes for Mechanical Sensor Applications

“…Meanwhile, this hexagonalization was found also for other types of nanotubes, such as inorganic imogolites . Currently, the topic of organic nanotubes made from π‐conjugated molecular systems different to CNTs (e.g., porphyrins and other tetrapyrrolic constituents involved in photosynthesis) has emerged in applied research, as these superstructures show interesting relationships between their structure and their mechanical, optical, and electronic properties and a high degree of biocompatibility …”

Synthesis of Finite Molecular Nanotubes by Connecting Axially Functionalized Macrocycles

“…[9][10][11][12][13][14][15][16][17] One-dimensional hollow nanostructures feature confined tubular space and anisotropic properties, representing an emerging category of artificial materials with increasing functions and applications during the past decades. [18][19][20][21][22][23][24][25][26][27][28][29][30] With a number of noteworthy exceptions, [9][10][11][12][13][14][15][16][17][31][32][33][34][35][36][37] (metallo)organic nanotubes are mostly obtained through selfassembly via non-covalent interactions such as hydrogen bonds and/or - interactions. [38][39][40][41][42][43][44][45][46][47]…”

New thiophene-based conjugated macrocycles for optoelectronic applications

“…Hence, it is of great interest to investigate different or novel molecular systems to allow the discovery of crucial structure-activity relationships that will allow the development of newer materials with enhanced processability and performance. [32][33][34][35][36][37] In both polymer and small molecule based bulk-heterojunction (BHJ) organic photovoltaics (OPVs), the self-assembly of photoactive materials is crucial to generate efficient devices. 38,39 Efficient interaction between donor and acceptor materials is needed to facilitate charge separation, 40 and appropriate intermolecular organisation favours charge transport.…”

“…A great number of reports have made available protocols for the synthesis of macrocycles composed of a wide variety of aromatic moieties such as: benzene, carbazole, thiophene, perylene, porphyrin, BODIPY, furan, acetylene and so forth. 35,54,56,[63][64][65][66][67][68][69][70][71][72][73] Previous work reports the synthesis of cycles of different molecular lengths and cavity sizes. 74,75 Some also report the formation of stable supramolecular complexes with different substrates.…”