•The nanotubes of p-HTClPP and p-HTClPPCo were obtained by AAO template method.•Different molecular structure can tune gas sensing properties of these nanotubes.•The lower detection limit of p-HTClPPCo nanotubes to NO2 can reach 500 ppb at room temperature.In the present study, the nanotubes of 5-(4-hydroxyphenyl)-10, 15, 20-tri(4-chlorophenyl) porphyrin (p-HTClPP) (1) and 5-(4-hydroxyphenyl)-10, 15, 20-tri(4-chlorophenyl) porphyrin cobalt (p-HTClPPCo) (2) were successfully prepared by using anodize alumina oxide (AAO) template method. The p-HTClPP and p-HTClPPCo nanotubes have been confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electronic absorption spectra, fluorescence spectroscopy, fourier transform infrared spectroscopy (FT-IR), low-angle X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) techniques. Both p-HTClPPCo and p-HTClPP nanotubes showed excellent sensitivity, reproducibility and selectivity toward NO2. Especially the prepared sensor of p-HTClPPCo nanotubes exhibited faster response/recovery characteristics and lower detection limit of NO2 (up to 500 ppb) than that of p-HTClPP nanotubes, which pave a new avenue in the gas sensitive field.Highly ordered p-HTClPP and p-HTClPPCo nanotubes were fabricated by the template method for the first time. Especially the prepared sensor of p-HTClPPCo nanotubes exhibited faster response/recovery characteristics and lower detection limit of NO2, which illustrated the relationship between molecular structure, molecular arrangement and gas sensing properties.Download high-res image (141KB)Download full-size image

A sandwich-type (phthalocyaninato)(porphyrinato) europium double-decker complex Eu(TPyP){Pc-(OC8H17)8} [TPyP = meso-tetra(4-pyridyl)porphyrin; Pc-(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] (2) was designed and prepared. For comparative studies, Eu(TPyP)(Pc) (1) was also prepared. Highly ordered nanotubes of complexes 1 and 2 were successfully fabricated by using an anodized alumina oxide (AAO) template method. The nanotubes were comparatively investigated by electronic absorption spectra, scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS) techniques. Both nanotubes of complexes 1 and 2 showed good conductivities and presented an efficient gas sensing platform for the ultrasensitive detection of NO2 at room temperature. In particular, the detection limit and response/recovery times for the proposed sensors based on complex 2 were lower and faster than those of complex 1, indicating the significant effect of a molecular packing mode on tuning the gas sensing performance of organic semiconductors.

•The desirable nanotubes of ZnTAP have been obtained by AAO template method.•This is the first attempt to use porphyrin nanotubes for the detection of NO2.•This opens a new avenue for the inexpensive, ultrasensitive detection of toxic gases.Highly ordered nanotubes of 5, 10, 15, 20-tetrakis(4-aminophenyl)porphyrin zinc (ZnTAP) are fabricated by using nanoporous anodized aluminum oxide (AAO) membrane as the template. Electronic absorption spectra, fluorescence spectra, transmission electron microscope (TEM), scanning electronic microscopy (SEM), low-angle X-ray diffraction (XRD) techniques are adopted to characterize these nanotubes. The highly ordered nanotubes of ZnTAP show good conductivity and present an efficient gas sensor platform for the ultrasensitive detection of NO2 under room temperature. The proposed sensor shows high sensitivity, reproducibility and fast response/recovery behavior, and provides a promising avenue for improving the sensing performance.Ordered nanotubes of 5, 10, 15, 20-tetrakis(4-aminophenyl)porphyrin zinc were fabricated by template method for the first time. Highly reproducible and sensitive NO2 gas response characteristics were observed in these nanotubes.

•A new porphyrin dendrimer was designed and synthesized.•Solvent effect on the self-assembly of porphyrin dendrimer was first studied.•The semiconducting properties of self-assembled aggregates were investigated.The self-assembly properties of the porphyrin dendrimer complex in polar and non-polar solvents (methanol and n-hexane) have been comparatively studied. The present result appears to represent the first effort toward realization of controlling and tuning the morphology of self-assembled aggregates of porphyrin complexes through the solvent effect.A new porphyrin dendrimer complex (G2ZnPor) was designed and synthesized. Its self-assembly behavior and the semiconducting properties in polar and non-polar solvents (methanol and n-hexane) have been comparatively studied, indicating the effective influence of solvent on the morphology, dimension and the semiconducting properties of the assembled aggregates.

The single crystal molecular structure of the tris(phthalocyaninato) terbium triple-decker [(Pc)Tb{Pc(OC8H17)8}Tb(Pc)] was determined by X-ray single-crystal diffraction analysis. Its self-assembling properties in chloroform and n-hexane vapors were comparatively investigated using UV, SEM and XRD techniques. Intermolecular π–π interactions, in cooperation with the van der Waals interaction of the triple-decker complex [(Pc)Tb{Pc(OC8H17)8}Tb(Pc)] and solvent–solute interactions, lead to the formation of dendrite-shaped and cube-shaped nanostructures in chloroform and n-hexane vapors, respectively. UV and XRD results clearly reveal the effect of the solvent on tuning the intermolecular interaction, and in turn, the molecular packing mode in the self-assembled nanostructures of [(Pc)Tb{Pc(OC8H17)8}Tb(Pc)]. Furthermore, the single crystal structure obtained through the present study renders it possible to investigate the formation mechanism as well as the molecular packing conformation of self-assembled nanostructures in a more confirmed manner.Graphical abstractThe single crystal molecular structure of the tris(phthalocyaninato) terbium triple-decker [(Pc)Tb{Pc(OC8H17)8}Tb(Pc)] was determined by X-ray single-crystal diffraction analysis. Comparative studies of the self-assembly properties of this triple-decker complex clearly reveal the effect of the solvent on the tuning of the intermolecular interaction, and in turn, the molecular packing mode in self-assembled nanostructures.Highlights► The single crystal molecular structure of triple-decker has been determined. ► The effect of the solvent on tuning intermolecular interaction has been revealed. ► The better semiconducting properties of 1D nanostructure have been reported.

A novel unsymmetrical ferrocene–porphyrin derivative, namely 5-(4-ferrocamidophenyl)-10,15,20-triphenylporphyrin (H2FcPor), is designed, synthesized and characterized. The self-assembly properties of this novel ferrocene–porphyrin in methanol and n-hexane are comparatively investigated by scanning electron microscopy (SEM), the X-ray diffraction (XRD) technique, Fourier transform infrared (FT-IR) spectroscopy and electronic absorption spectroscopy. Intermolecular π–π interaction in cooperation with the solvent–solute interaction and the absence or presence of intermolecular hydrogen bonding leads to the formation of nanospheres and nanobelts in methanol and n-hexane, respectively. When applied as gas sensors, both the nanospheres and the nanobelts exhibit excellent gas sensitivity, and good stability and selectivity at room temperature for NO2 detection. Under the same measurement conditions, the detection limit and recovery times of nanobelt gas sensors are lower and faster than those for nanosphere gas sensors. Surprisingly, the nanospheres exhibit a normal n-type gas-sensing response to NO2, while the nanobelts display p-type gas-sensing behaviour in different NO2 concentration ranges. The abnormal sensing behavior with transition from n- to p-type NO2 sensing is tuned by solvent–porphyrin molecule interaction and molecular packing mode for the first time.

A sandwich-type (phthalocyaninato)(porphyrinato) europium double-decker complex Eu(TPyP){Pc-(OC8H17)8} [TPyP = meso-tetra(4-pyridyl)porphyrin; Pc-(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] (2) was designed and prepared. For comparative studies, Eu(TPyP)(Pc) (1) was also prepared. Highly ordered nanotubes of complexes 1 and 2 were successfully fabricated by using an anodized alumina oxide (AAO) template method. The nanotubes were comparatively investigated by electronic absorption spectra, scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS) techniques. Both nanotubes of complexes 1 and 2 showed good conductivities and presented an efficient gas sensing platform for the ultrasensitive detection of NO2 at room temperature. In particular, the detection limit and response/recovery times for the proposed sensors based on complex 2 were lower and faster than those of complex 1, indicating the significant effect of a molecular packing mode on tuning the gas sensing performance of organic semiconductors.