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Renewable superhydrophobic surfaces based on laminated polymer films with nanopillar array structures were prepared. Polymer nanopillar arrays exhibiting superhydrophobic properties were prepared by nanoimprinting using anodic porous alumina as a mold. The hydrophobic properties of the obtained polymer nanopillar arrays could be controlled and optimized by changing the geometrical structures of anodic porous alumina molds used for nanoimprinting. The polymer films were laminated using a photocurable monomer. The ordered polymer nanopillar array structures could be maintained even after delamination of the films. Renewed polymer nanopillar arrays exposed by peeling off the upper films exhibited a water contact angle higher than 150°. Using this process, superhydrophobic surfaces could be obtained repeatedly by delamination of a film even when superhydrophobicity deteriorated with the collapse of surface patterns. The obtained renewable superhydrophobic surfaces can be used for various applications requiring high durability.

Ordered anodic porous alumina with controlled-size holes on the order of a single-nanometer scale was obtained by the atomic layer deposition (ALD) of Al2O3 or TiO2. The thin metal oxide layers of uniform thickness were formed successfully on the inner wall of the hole of the ordered anodic porous alumina with high aspect ratios by ALD. The hole diameter of the ordered anodic porous alumina could be controlled precisely by adjusting the number of cycles of ALD. The obtained anodic porous alumina with an ordered hole arrangement of reduced holes will be applied to various application fields requiring uniform-sized holes on the order of a single-nanometer scale, such as the starting material for preparing various types of quantum effect devices.

Self-ordered anodic porous alumina with a long-range ordered hole arrangement having an inter-hole spacing of over 1.5 μm was prepared by anodization in a citric acid electrolyte containing a small amount of phosphoric acid. The inter-hole spacing of the ordered anodic porous alumina could be controlled within a range of 700 nm to 1.8 μm by adjusting the anodization conditions. The use of an electrolyte with a mixture of water and ethylene glycols, especially tetraethylene glycol, was effective for preparing ordered anodic porous alumina with large inter-hole spacings. The obtained anodic porous alumina is suitable for various applications that require highly ordered hole array structures with large inter-hole spacings.

Polymer nanofibers with controlled diameters were formed by continuous spinning using ordered anodic porous alumina as a spinneret. The diameter of the polymer nanofibers could be controlled by cha...

In this study, highly ordered anodic porous metal oxides of transition metals (W, Fe, Co, and Nb) were prepared by anodization combined with a pretexturing process. The formation of an array of dimples on the metal surface was achieved by dry etching using ordered anodic porous alumina as a mask. Subsequent anodization of the pretextured metals generated metal oxides (WO3, Fe2O3, Co3O4, and Nb2O4) with an ordered hole array structure because each dimple acted as a starting point for hole development. The hole periodicity of the resulting ordered anodic porous metal oxide could be controlled by changing the periodicity of the dimples formed on the substrate. Ordered anodic porous films obtained by this process could be used in various functional devices that require ordered hole array structures.

Anodic porous alumina templates with controlled microscale geometrical structures were prepared by a process combining mask formation and subsequent selective etching of the alumina layer. In this process, the anisotropic etching of anodic porous alumina allows the preparation of anodic porous alumina with microhole array patterns having high aspect ratios. The electrodeposition of Ni using the obtained alumina templates generated an array of Ni micropillars with high aspect ratios. The height of Ni micropillars could also be controlled by adjusting the thickness of the anodic porous alumina. The obtained Ni micropillar array with a high aspect ratio was applied as a mold for imprinting. The ordered microstructures of TiO2 with high aspect ratios were prepared by imprinting using the Ni mold.

Multilayered porous hollow spheres were obtained by the periodic anodization of small Al particles in different electrolytes and subsequent selective etching. The periodic anodization of small Al particles in concentrated H2SO4 and oxalic acid generated oxide layers on their surface with a periodically modulated solubility in the thickness direction. Hollow spheres composed of multilayered porous alumina shells were prepared by the subsequent etching of residual Al and the oxide layers formed in concentrated H2SO4. The resulting multilayered hollow spheres had a large specific surface area originating from their unique geometrical structure and are expected to find use in various applications such as catalysts, sensors, and drug carriers.

The fabrication of anodic porous alumina with anisotropic structures, i.e., an anisotropic hole arrangement and anisotropic elliptical hole shape, was demonstrated. Through the optimization of the pattern used for the pretexturing and the anodizing conditions, anodic porous alumina with holes having an elliptical cross section could be satisfactory obtained. The diameter of the elliptical nanoholes could be controlled by an additional wet-etching process. The obtained anodic porous alumina with elliptical nanoholes is expected to be applied to various functional optical devices, such as localized plasmonic devices, requiring control of the anisotropy of the incident light. Keywords: Anodization, Anodic porous alumina, Elliptical nanohole, Pretexturing

Anodic porous alumina membranes with site controlled through-holes were prepared by the formation of a masking layer on the surface of anodic porous alumina and subsequent selective second anodization in concentrated sulfuric acid to form a readily soluble layer. After the anodization, the residual Al substrate was removed, and the highly soluble alumina layer formed in concentrated sulfuric acid was dissolved selectively by wet etching. An advantageous point of this process is the controllability of the pattern of through-holes, and the preparation of large samples with selective through-holes is possible. The pattern of through-holes was controlled by changing the mask pattern formed on the surface of anodic porous alumina. The alumina membranes obtained by this process are expected to be used for various applications that require porous alumina membranes with site controlled through-holes.

Polymer micro/nano hierarchical structures were successfully formed by photo-nanoimprinting using anodic porous alumina molds. Anodic porous alumina molds with hierarchical structures were prepared by the anodization of an Al substrate with a micro-concave array. The obtained surfaces with hierarchical structures exhibited superhydrophobicity. The hydrophobic properties of the obtained samples were dependent on the surface structures and could be optimized by changing the micro- and nanopatterns in the hierarchical structure.

Nanoporous alumina spheres with an ordered hole arrangement were prepared through a two-step anodization of small Al particles. The hole periodicity in the ordered anodic porous alumina could be controlled by adjusting the anodizing conditions. Nanoporous hollow spheres were also obtained by removal of residual Al in an etchant. Additionally, nanoporous spheres loaded with Au nanoparticles on their surfaces were obtained through electrochemical or chemical deposition of Au nanoparticles. The obtained Au/alumina composite hollow spheres were used as a substrate for surface-enhanced Raman scattering measurements.

A new type of process for the fabrication of ideally ordered anodic porous alumina with the desired hole interval based on the deformation of a polymer template and the subsequent formation of a metal mold is described. In this process, a pattern composed of an ordered array of concave structures is first prepared on a polymer sheet by imprinting using a starting metal (Ni) mold, and the interval in the pattern is tuned through the deformation of the polymer sheet. The Ni mold with the pattern having the tuned interval is formed by the electroplating of Ni using the polymer sheet as a template. Finally, the pretexturing of Al by imprinting using the obtained Ni mold and subsequent anodization generate ideally ordered anodic porous alumina with the desired hole interval.

Geometrically controlled Li nanohole arrays with high aspect features were fabricated by a two-step replication process using ordered anodic porous alumina as a template. The use of an appropriate electrolyte for Li electrodeposition and organic solvent for the removal of the polymer (PMMA) template allowed the preparation of Li nanohole arrays with precisely replicated nanostructures. The application of a template with the structures for the electrodeposition of Li contributed to the suppression of the formation of Li dendrites, contributing to the precise replication.

We studied the formation of ideally ordered nanoporous zirconia by anodizing Zr having a texturing pattern. A texturing pattern was formed on a Zr surface by peeling off a sputtered zirconium film from a metal (Ni) mold having an ordered array of convexes. In contrast to texturing by nanoimprinting, the present texturing process never requires the pressing of a mold onto the Zr surface. During the anodization of Zr that has a texturing pattern on its surface, which is an ideally ordered array of concaves, each concave acted as a starting point of the formation of nanoholes. By the present process, porous anodic zirconia having an ideally ordered array of nanoholes was obtained. The interval between nanoholes in the porous anodic zirconia agreed with the texturing pattern.

We obtained monodisperse albumin particles by membrane emulsification using ordered anodic porous alumina with uniform-sized holes. The particle size could be controlled by adjusting the hole size in the alumina emulsification membrane using the linear relationship between the size of particle and the hole. We loaded a fluorescent dye into the albumin particles by adding it to the dispersed phase used for the emulsification. These monodisperse albumin particles with controlled size have potential for use in various applications, in particular, as drug carriers.

SnO2 nanofibers with uniform diameters were obtained by wet spinning using ordered anodic porous alumina as a spinneret, followed by heat treatment. Ordered alumina through-hole membrane is a suitable spinneret material for nanofiber spinning owing to its nanohole array structure with uniform-sizes holes. A polymer solution containing a Sn salt was used as a precursor solution for the wet spinning. Polymer nanofibers containing the Sn salt were continuously formed as the precursor passed through the alumina holes into a coagulating solution. Monodisperse nanofiber structures were successfully maintained, even after heat treatment at 600 °C. This process enabled the preparation of monodisperse SnO2 nanofibers with diameters below 100 nm, as well as the precise control of fiber diameter by changing the hole size of the porous alumina spinneret. The obtained SnO2 nanofibers will be useful in various functional devices.

Highly ordered Au nanorod arrays were fabricated using anodic porous alumina with elliptical nanoholes as an evaporation mask and applied as a substrate for measurements of surface-enhanced Raman scattering (SERS) spectra. Shape of nanoholes in anodic porous alumina obtained by self-ordering anodization process is usually circular. In the present study, elliptical nanoholes ordered in rectangular lattice were successfully fabricated by lattice conversion process using naturally ordered anodic porous alumina. The Au nanorod arrays were fabricated by thermal evaporation using the obtained anodic porous alumina. The SERS activity of the Au nanorods were higher than that of a circular Au nanodots.

Ideally ordered anodic porous TiO2 was fabricated by anodizing an Al/Ti layered specimen. A two-layered specimen composed of an Al top layer and a Ti underlying layer was prepared and then processed by nanoimprinting. The Al top layer was easily pretextured by nanoimprinting owing to its softness and it was straightforward to introduce an ideally ordered pore arrangement by anodization. This pore arrangement was transferred to the underlying Ti layer, resulting in ideally ordered porous structures in TiO2. This process can be applied to the high-throughput fabrication of ideally ordered anodic porous oxides other than TiO2 and also to other metals with high hardness. Keywords: Porous TiO2, Anodization, Imprinting process

Anodic porous alumina, which is a typical self-ordered nanohole array material formed by anodization of Al in an appropriate acid solution, has recently attracted increasing interest as a key material for the fabrication of functional devices1,2). For the various applications of ordered anodic porous alumina, the preparation of through-hole membranes is important. The fabrication process for porous alumina through-hole membranes has been investigated for a long time3). However, a facile and reliable process that does not require special techniques has not yet been established. To overcome this problem, we have been developing a new high-throughput process for fabricating through-hole alumina membranes4). This process is based on the new finding that through-hole membranes can be easily obtained by dissolving a two-layered sample in an appropriate etchant, which was formed by a first anodization under standard anodizing conditions and a subsequent anodization in concentrated H2SO4. This is because the oxide layer formed in the concentrated H2SO4 can be easily dissolved in an appropriate etchant. After the detachment of the membrane, the residual Al substrate could be repeatedly used for the preparation of ordered through-hole membranes. In this report, recent results of the preparation of ordered anodic porous alumina through-hole membranes and its applications will be presented. References 1) T. Yanagishita and T. Hidaka, M. Suzuki, and H. Masuda, J. Vac. Sci. Technol. B, 34, 021804 (2016). 2) H. Masuda and K. Fukuda, Science, 268, 1466 (1995). 3) H. Masuda and M. Satoh, Hpn. J. Appl/ Phys., 35, L126 (1996). 4) T. Yanagishita and H. Masuda, Electrochim. Acta, 184, 80 (2015).

Porous Al particles were prepared by anisotropic anodic etching of small Al particles. The anisotropic anodic etching was carried out in a Cl− containing electrolyte using a close-packed Al particle structure in which particles were electrically connected through the contact points between them. Anisotropic tunnel pits in the 〈100〉 direction of the Al crystal lattice were formed in the particles. After the etching, the porous Al particles could be dispersed from the close-packed structure easily. The average depth of the etching pits was ca. 25μm. The obtained porous Al particles will be useful for various functional devices which require large surface area, such as substrates for catalysts and electrodes for electrolytic capacitors. Keywords: Porous Al, Anode etching, Porous particles, Etching pits

Ordered anodic porous alumina through-hole membranes with a hole period larger than 500 nm were fabricated by two-layer anodization. Formation of the ordered anodic porous alumina with a hole period larger than 500 nm was carried out by anodization of Al in phosphoric acid or mixture of malic acid and phosphoric acid. Two-layered structures comprising porous alumina layers with different solubilities were formed by anodization using two electrolytes, one of which was 17.6 M sulfuric acid. The membranes were prepared by selectively etching the lower part of the alumina layer formed in 17.6 M sulfuric acid. The thickness of the membranes was controlled by adjusting the anodization time. The obtained membranes are expected to be used in various applications such as filtration membranes.

High-aspect nanostructure, such as a nanohole and a coaxial nanocable, are considered as a powerful candidate for a light waveguide. Especially, a coaxial nanocable can efficiently propagate the incident light because the coaxial nanocable does not have cut-off wavelength as seen in a nanohole. In addition, by reducing the opening size of the coaxial nanocable, the coaxial nanocable can propagate the light to an area less than a wavelength of the incident light beyond the diffraction limit. Therefore, the coaxial nanocable is expected to be applied to fabricate various types of functional optical devices, such as nanoimaging device and high-density optical recording device. However, it is still difficult to fabricate the high-aspect nanostructure with complicated geometrical features such as the coaxial nanocable because of fabrication difficulties. Until now, our group had been reported fabrication process of the high-aspect metal nanostructures using an anodic porous alumina and its optical property [1-3]. Anodic porous alumina has an ordered array of straight nanoholes having high aspect ratio. Due to this unique geometrical character, anodic porous alumina is commonly used as a starting material to fabricate nanostructures having high aspect feature. In our previous work, we reported fabrication of the coaxial nanocables having high aspect ratio using anodic porous alumna [3]. In addition, it was observed that the coaxial nanocable could efficiently propagate the visible light. In the present work, with the aim of improving the performance of the functional devices based on the coaxial nanocable, reduction of opening size of the coaxial nanocable and evaluation of the optical property were demonstrated. This fabrication process is expected to be applied to fabricate various types of functional optical devices requiring the fine coaxial nanocable. K. Nishio, M. Nakao, A. Yokoo, H. Masuda, Jpn. J. Appl. Phys., 42, L83 (2003). T. Kondo, N. Kitagishi, T. Yanagishita, H. Masuda, Appl. Phys. Express, 8, 06200 (2015). T. Kondo, R. Ichinose, M. Kurosawa, T. Yanagishita, H. Masuda, The 87th ECSJ Spring Meeting, 1C06 (2020).

Moth-eye structures composed of an ordered array of tapered pillars have attracted increasing interest owing to their application such as displays, lenses and solar cells. A large number of methods have been reported for the preparation of moth-eye structures. Among them, nanoimprinting is a promising method for the high-throughput preparation of moth-eye structures with large sample areas. In our previous works, we have reported that an ordered anodic porous alumina can be used for a nanoimprinting mold to prepare seamless moth-eye surfaces with large sample areas [1,2]. In this process, the moth-eye structures with optimized antireflection properties was obtained by adjusting the preparation conditions of porous alumina molds. One problem currently limiting the practical use of moth-eye structures is their low durability. This problem originates from the fine, high-aspect geometrical features of moth-eye structures. Improved durability is essential for practical application of moth-eye structures as antireflection surfaces. In the present report, we describe the preparation of renewable antireflection surfaces by nanoimprinting using an anodic porous alumina mold. Renewable antireflection surfaces were formed by the lamination of polymer thin films with moth-eye structured surfaces [3]. Thin-film lamination was performed using a photocurable monomer as an adhesive. A renewed low-reflectance moth-eye structured surface could be exposed by peeling the uppermost film from the sample. Each exposed surface with moth-eye structure successfully lowered the reflection of incident light. The obtained renewable antireflection surfaces are expected to be applicable to several types of optical devices requiring high durability, such as the surface panels of displays. T. Yanagishita, K. Nishio, and H. Masuda, Appl. Phys. Express, 2, 022001 (2009). T. Yanagishita, T. Hidaka, M. Suzuki, and Hideki Masuda, J. Vac. Sci. Technol. B, 34, 021804 (2016). T. Yanagishita, T. Kondo, and H. Masuda, J. Vac. Sci. Technol. B, 36, 031802 (2018).

Alumina through-hole membranes with an ordered array of holes were obtained by the wet etching of two-layered anodic porous alumina, which was formed by the first anodization of Al in an acid solution under standard conditions and the subsequent anodization in concentrated H2SO4. In this process, the detachment of the porous alumina membrane and through-holing could be achieved simultaneously by etching in an appropriate acid solution. This is because the oxide layers formed in concentrated H2SO4 were more easily dissolved than the oxide layer formed in the standared acid solution. After the detachment of the membrane, the residual Al substrate could be repeatedly used for the preparation of ordered through-hole membranes. The obtained through-hole membranes are expected to be used in various applications.

TiO2 hollow spheres with nanoporous structures on their surfaces were prepared by the anodization of small Ti particles and the subsequent leaching of the residual metal. The geometrical structures of the TiO2 porous layers could be controlled by changing the anodization conditions. Au-loaded TiO2 hollow spheres were also obtained by depositing Au nanoparticles on the surface of the TiO2 spheres. The obtained porous hollow spheres and metal loaded TiO2 composite hollow spheres can be applied to various types of functional devices.

Ideally ordered anodic porous TiO2 was fabricated through the pretexturing of Ti by nanoimprinting using a metal mold with an ordered array of convexes. The shallow concaves prepared by nanoimprinting acted as initiation sites for hole development during the subsequent anodization and generated ideally hexagonally ordered porous or nanotubular TiO2. The hole interval of the ideally ordered TiO2 could be controlled by changing the pretexturing pattern. This process is a key step towards the preparation of various types of functional devices requiring ideally ordered defect-free hole or pore arrangements. Keywords: Porous TiO2, Anodization, Ti, Imprinting process, Nanotubes

Porous Si particles were prepared by the barrel anode etching of small Si particles. The depth of the holes formed on the surface of the Si particles could be controlled by changing the anode etching time. The process reported here allows high-throughput preparation of small porous Si particles with controlled geometrical surface structures. The obtained porous Si particles can be applied in various types of functional devices.

Uniform-sized nanoparticles of metal oxides were fabricated by membrane emulsification using ordered anodic porous alumina as a membrane and subsequent solidification. The size of the nanoparticles could be controlled by adjusting the pore size of the anodic porous alumina membrane. This process allows the high throughput preparation of monodisperse nanoparticles of various types of metal oxide with controlled size due to the capability of continuous formation of monodisperse emulsion droplets through the porous membrane.

An anodic porous alumina mold with tapered holes was formed by a one-pod preparation process. In this process, one-pod of a mixed solution containing oxalic acid and phosphoric acid was used for both anodization and pore widening. The anodization proceeded during the on state of the applied voltage, while the pore widening proceeded during the off state. The shape of the tapered holes in anodic porous alumina could be controlled by adjusting the program composed of on and off periods. Moth-eye structures were formed by nanoimprinting using the obtained molds. These moth-eye structures effectively suppressed the reflection of incident light.

Arrays of carbon nanofibers with high aspect ratios were fabricated from polymer pillars prepared by nanoimprinting using anodic porous alumina mol ds. In the present study, arrays of polymer pillars with an aspect ratio of up to 120 were obtained by nanoimprinting using a photocurable monomer. Then, carbon nanofiber arrays were formed from the polymer nanofiber arrays. The ordered fine structures of the polymer nanofiber arrays were successfully maintained even after heat treatment for carbonization. The obtained carbon nanofiber arrays are expected to be useful for various applications.

Enlargement of the surface area of Al foils was carried out through the electrochemical insertion and deinsertion of Li. The electrochemical insertion and deinsertion of Li generated a fine porous structure on the surface of the Al foils. The specific surface area increased with the number of insertion and deinsertion cycles of Li and reached 300. This process can be applied to the effective enlargement of the surface area of Al foils, which is essential for increasing the capacitance of Al electrolytic capacitors. Keywords: Nanoporous film, Electrochemical alloying, Electrochemical dealloying, Lithiation, Delithiation

The fabrication of geometrically controlled nanodot arrays based on anodic porous alumina and their application as substrates used for surface-enhanced Raman scattering (SERS) measurements were studied. Ordered arrays of circular, square, and triangular Au nanodots were obtained using anodic porous alumina as an evaporation mask. The shape and arrangement of the nanodots were precisely controlled by adjusting the geometrical structure of the nanoholes in the anodic porous alumina. We also fabricated triangular nanodots that had sharp corners with a curvature radius of 15 nm. SERS spectra of pyridine molecules adsorbed on the Au nanodots were measured using the obtained nanodot arrays as substrates for measurements. The SERS intensity obtained from the triangular nanodot array was strongly enhanced compared with that obtained from the array of circular nanodots. The intensity of signals was dependent on the shape and arrangement of the nanodots. It is expected that nanodot arrays obtained by this fabricati...

Properties of newly developed Ru(II)-complex dye, cis -bis(isothiocyanato) (2,2′-bipyridyl-4,4′-dicarboxylato) ( N -(4-butoxyphenyl)- N -2-pyridinyl-2-pyridinamine)-ruthenium(II) (J13), having a triarylamine ligand have been studied in comparison with cis -bis(isothiocyanato) bis(2,2′-bipyridyl-4,4′-dicarboxylato)-ruthenium(II) (N3), as photosensitizers for solar cells employing electrodeposited porous ZnO thin films. Quantification of dye loading as well as change of the film morphology on extension of the soaking time in solutions of these dyes indicated spontaneous monolayer formation of the J13 dye, in contrast to the strongly aggregating N3 dye. Overloading of the N3 dye molecules not directly bound to ZnO caused decreased J sc as well as worsening of F.F. , so that the efficiency of the N3 cell created a peak with a moderate dipping time. On the other hand, the efficiency of the J13 cells simply saturated to a value of ca. 4% as the dye monolayer was formed, indicating its better chemical match with ZnO.

An anodic porous alumina with precisely controlled size and depth of holes was prepared and used for nanoimprinting of a polymer. As a typical application of nanoimprinting, antireflection (AR) structures of polymer were prepared. The obtained AR structure with optimized geometrical structures exhibited a low reflectance of less than 0.2 %. The present process allows the high throughput production of polymer AR structures with large sizes.

Renewable antireflection surfaces were formed by the lamination of polymer thin films with moth-eye structured surfaces. Moth-eye structures were prepared by nanoimprinting using an anodic porous alumina mold. Thin-film lamination was performed using a photocurable monomer as an adhesive. A renewed low-reflectance moth-eye structured surface could be exposed by peeling the uppermost film from the sample.Renewable antireflection surfaces were formed by the lamination of polymer thin films with moth-eye structured surfaces. Moth-eye structures were prepared by nanoimprinting using an anodic porous alumina mold. Thin-film lamination was performed using a photocurable monomer as an adhesive. A renewed low-reflectance moth-eye structured surface could be exposed by peeling the uppermost film from the sample.

Uniformly sized droplets of photocurable monomer were obtained through membrane emulsification using highly ordered anodic porous alumina as a membrane. Subsequent polymerization of the monomer generated polymer particles, whose sizes could be controlled by changing the size of the pores in anodic porous alumina. The size distribution was very narrow owing to the uniformity of pore size in the anodic porous alumina used for the emulsification.

The fabrication of functional surfaces with fine ordered structures from submicron to nanometer scales has attracted increasing attention due to its application in various fields. In the present report, fabrication of several types of functional ordered surfaces based on the highly ordered anodic porous alumina are described. Anodic porous alumina, which is formed by anodization of Al in acidic electrolyte, is a typical self-ordered material and is promising candidate for the nanofabrication. As typical example of the fabrication of ordered surfaces, the highly ordered structures of the anodic porous alumina could be applied to the mask processes, in which the metal dot arrays or hole arrays are formed on the substrates. Some typical examples of the application of the obtained ordered surfaces were also described

The optimization of antireflection (AR) structures of polymer composed of an ordered array of tapered pillars was studied. An anodic porous alumina mold with precisely controlled tapered holes was prepared and used for photoimprinting of the polymer. The reflectance of the obtained AR polymer structures with conical pillars was evaluated through the measurement of transmittance. Among the AR structures with pillars with various slopes, those with a gradually changing slope exhibited the lowest reflectance. The fabrication process will be effective for the formation of an AR surface with minimized reflectance over a large sample area.

A disodium tetrakis(phthalimide) palladium(II) complex, [Na2Pd(phthal)4] (1), was synthesized by reaction of four phthalimide molecules with Pd(OAc)2 in the presence of Et3N. The above and below axial sites of the Pd coordination plane formed the spaces suitable for capturing Na+ ions, which were coordinated with the four imidato oxygen atoms. The complex 1 was linked through the Na+ ions bridged by the water molecules, building an infinite chain structure along the crystallographic a axis. The four phthalimidato moieties contacted in the four orthogonal directions together through their π-π stacking interaction. Such a self-assembly of molecule 1 constructed nanopores with a pore size of ca. 3 × 4 Å in the crystals.