Porphyrin nanoassemblies via surfactant-assisted assembly and single nanofiber nanoelectronic sensors for high-performance H₂O₂ vapor sensing

Nonlinear Optical Properties of Zn(II) Porphyrin, Graphene Nanoplates, and Ferrocene Hybrid Materials

Following some previous work by some of us on the second order nonlinear optical (NLO) properties of Zn(II) meso-tetraphenylporphyrin (ZnP), fullerene, and ferrocene (Fc) diads and triads, in the present research, we explore the NLO response of some new hybrids with two-dimensional graphene nanoplates (GNP) instead of a zero-dimensional fullerene moiety as the acceptor unit. The experimental data, collected by Electric Field Induced Second Harmonic generation (EFISH) technique in CH2Cl2 solution with a 1907 nm incident wavelength, combined with Coupled-Perturbed (CP) and Finite Field (FF) Density Functional Theory (DFT) calculations, show a strongly enhanced contribution of the cubic electronic term γ(-2ω; ω, ω, 0), due to the extended π-conjugation of the carbonaceous acceptor moiety.

Femtosecond Laser-Assisted Device Engineering: Toward Organic Field-Effect Transistor-Based High-Performance Gas Sensors

Organic electronic-based gas sensors hold great potential for portable healthcare- and environment-monitoring applications. It has recently been shown that introducing a porous structure into an organic semiconductor (OSC) film is an efficient way to improve the gas-sensing performance because it facilitates the interaction between the gaseous analyte and the active layer. Although several methods have been used to generate porous structures, the development of a robust approach that can facilely engineer the porous OSC film with a uniform pore pattern remains a challenge. Here, we demonstrate a robust approach to fabricate porous OSC films by using a femtosecond laser-processed porous dielectric layer template. With this laser-assisted strategy, various polymeric OSC layers with controllable pore size and well-defined pore patterns were achieved. The consequent porous p-type polymer-based device exhibits enhanced sensitivity to the ammonia analyte in the range from 100 ppb to 10 ppm with remarkable reproducibility and selectivity. The micropattern of the active layer was precisely controlled by generating various pore densities in the predecorated templates, which results in modulated ammonia sensitivities ranging from 30 to 65% ppm^-1. Furthermore, we show that this approach can be used to fabricate flexible gas sensors with enhanced sensing performance and mechanical durability, which indicate that this femtosecond laser-assisted approach is very promising for the fabrication of next-generation wearable electronics.

Self-assembly of FeIII-TAML-based microstructures for rapid degradation of bisphenols

Iron(III)-tetraamidomacrocyclic ligand (Fe^III-TAML) activators have drawn great attentions due to the high reactivity to degrade organic pollutants. However, previous studies showed that the reactivity and stability of Fe^III-TAML were both strongly pH-dependent, which dramatically decrease at lower pH levels. Herein, Fe^III-TAML/DODMA (dimethyldioctadecylammonium chloride) microspheres with diameters ranging from 100 to 2000 nm were synthesized via a surfactant-assisted self-assembly technique. The newly synthesized Fe^III-TAML/DODMA composite exhibits superior reactivity compared to free Fe^III-TAML as indicated by the degradation of bisphenols (i.e., bisphenol A and its analogues) over a wide pH range (i.e., pH 4.5-10.0). Based on the adsorption results and quantitative structure-activity relationship (QSAR) models, the enhanced reactivity of Fe^III-TAML/DODMA is mainly ascribed to the hydrophobic sorption of bisphenols. Moreover, the enhanced ionization of the axial water molecule associated with Fe^III-TAML could further enhance the reactivity of synthesized microcomposites, which was confirmed by the results of infrared and Raman spectra. Furthermore, Fe^III-TAML/DODMA shows distinct acid-resistance as explained by the protection of the hydrophobic alkyl chains of DODMA. This novel method would provide a simple and effective strategy to expand the application of Fe^III-TAML in a wide pH range and render Fe^III-TAML/DODMA microstructure as a potential catalyst for treatment of bisphenol compounds.

The formation mechanism of ZnTPyP fibers fabricated by a surfactant-assisted method

Zn–N coordination and the sphere-to-rod transition of CTAB micelles contribute concertedly to the formation of ZnTPyP fibers.

The Emergence of Organic Single-Crystal Electronics

Organic semiconducting single crystals are perfect for both fundamental and application-oriented research due to the advantages of free grain boundaries, few defects, and minimal traps and impurities, as well as their low-temperature processability, high flexibility, and low cost. Carrier mobilities of greater than 10 cm²  V^-1  s^-1 in some organic single crystals indicate a promising application in electronic devices. The progress made, including the molecular structures and fabrication technologies of organic single crystals, is introduced and organic single-crystal electronic devices, including field-effect transistors, phototransistors, p-n heterojunctions, and circuits, are summarized. Organic two-dimensional single crystals, cocrystals, and large single crystals, together with some potential applications, are introduced. A state-of-the-art overview of organic single-crystal electronics, with their challenges and prospects, is also provided.

Photoresponsive Porphyrin Nanotubes of Meso-tetra(4-Sulfonatophenyl)Porphyrin and Sn(IV) meso-tetra(4-pyridyl)porphyrin

Porphyrin macrocycles and their supramolecular nanoassemblies are being widely explored in energy harvesting, sensor development, catalysis, and medicine because of a good tunability of their light-induced charge separation and electron/energy transfer properties. In the present work, we prepared and studied photoresponsive porphyrin nanotubes formed by the self-assembly of meso-tetrakis(4-sulfonatophenyl)porphyrin and Sn(IV) meso-tetra(4-pyridyl)porphyrin. Scanning electron microscopy and transmission electron microscopy showed that these tubular nanostructures were hollow with open ends and their length was 0.4–0.8 μm, the inner diameter was 7–15 nm, and the outer diameter was 30–70 nm. Porphyrin tectons, H₄TPPS42- : Sn(IV)TPyP⁴⁺, self-assemble into the nanotubes in a ratio of 2:1, respectively, as determined by the elemental analysis. The photoconductivity of the porphyrin nanotubes was determined to be as high as 3.1 × 10⁻⁴ S m⁻¹, and the dependence of the photoconductance on distance and temperature was investigated. Excitation of the Q-band region with a Q-band of SnTPyP⁴⁺ (550–552 nm) and the band at 714 nm, which is associated with J-aggregation, was responsible for about 34 % of the photoconductive activity of the H₄TPPS42--Sn(IV)TPyP⁴⁺ porphyrin nanotubes. The sensor properties of the H₄TPPS42-- Sn(IV)TPyP⁴⁺ nanotubes in the presence of iodine vapor and salicylate anions down to millimolar range were examined in a chemiresistor sensing mode. We have shown that the porphyrin nanotubes advantageously combine the characteristics of a sensor and a transducer, thus demonstrating their great potential as efficient functional layers for sensing devices and biomimetic nanoarchitectures.

Functional Supramolecular Gels Based on the Hierarchical Assembly of Porphyrins and Phthalocyanines

Supramolecular gels containing porphyrins and phthalocyanines motifs are attracting increased interests in a wide range of research areas. Based on the supramolecular gels systems, porphyrin or phthalocyanines can form assemblies with plentiful nanostructures, dynamic, and stimuli-responsive properties. And these π-conjugated molecular building blocks also afford supramolecular gels with many new features, depending on their photochemical and electrochemical characteristics. As one of the most characteristic models, the supramolecular chirality of these soft matters was investigated. Notably, the application of supramolecular gels containing porphyrins and phthalocyanines has been developed in the field of catalysis, molecular sensing, biological imaging, drug delivery and photodynamic therapy. And some photoelectric devices were also fabricated depending on the gelation of porphyrins or phthalocyanines. This paper presents an overview of the progress achieved in this issue along with some perspectives for further advances.

Encapsulation of Gold Nanorods with Porphyrins for the Potential Treatment of Cancer and Bacterial Diseases: A Critical Review

Cancer and bacterial diseases have been the most incidental diseases to date. According to the World Health Report 2018, at least every family is affected by cancer around the world. In 2012, 14.1 million people were affected by cancer, and that figure is bound to increase to 21.6 million in 2030. Medicine therefore sorts out ways of treatment using conventional methods which have been proven to have many side effects. Researchers developed photothermal and photodynamic methods to treat both cancer and bacterial diseases. These methods pose fewer effects on the biological systems but still no perfect method has been synthesized. The review serves to explore porphyrin and gold nanorods to be used in the treatment of cancer and bacterial diseases: porphyrins as photosensitizers and gold nanorods as delivery agents. In addition, the review delves into ways of incorporating photothermal and photodynamic therapy aimed at producing a less toxic, more efficacious, and specific compound for the treatment.

Mesoporous WO3 Nanofibers With Crystalline Framework for High-Performance Acetone Sensing

Semiconducting metal oxides with abundant active sites are regarded as promising candidates for environmental monitoring and breath analysis because of their excellent gas sensing performance and stability. Herein, mesoporous WO₃ nanofibers with a crystalline framework and uniform pore size is successfully synthesized in an aqueous phase using an electrospinning method, with ammonium metatungstate as the tungsten sources, and SiO₂ nanoparticles and polyvinylpyrrolidone as the sacrificial templates. The obtained mesoporous WO₃ nanofibers exhibit a controllable pore size of 26.3–42.2 nm, specific surface area of 24.1–34.4 m²g⁻¹, and a pore volume of 0.15–0.24 cm³g⁻¹. This unique hierarchical structure, with uniform mesopores and interconnected channels, could facilitate the diffusion and transportation of gas molecules in the framework. Gas sensors, based on mesoporous WO₃ nanofibers, exhibit an excellent performance in acetone sensing with a low limit of detection (<1 ppm), short response-recovery time (24 s/27 s), a linear relationship in a broad range, and good selectivity.

Control of post-growth processes for the selection of metallo-tetraphenylporphyrin nanowires

Controlling self-organization of small organic molecules in nanostructures with a desired shape and size is one of the main challenges in organic nanoelectronics. Here, a strategy for selectively growing uniaxially aligned nanowires of meso-tetraphenyl porphyrin-Zn(ii) (ZnTPP) is presented. ZnTPP is deposited on an organic single crystal, namely potassium hydrogen phthalate, by organic molecular beam epitaxy. The films typically display a rather rich surface morphology, characterized by the presence of nanowires and other nm-sized aggregates, most of them unstable over time. Post-growth processes occurring via quasi-Ostwald ripening both in air and in vacuum demonstrate an aging protocol in vacuum as a tool for the selection of ZnTPP nanowires, whose morphology and uniaxial orientation are demonstrated to be led by organic epitaxy. The ability of growing ZnTPP nanowires with a unique crystal structure and precise orientation gives the chance to observe the intrinsic optical anisotropy of the triclinic polymorph of ZnTPP crystal and establishes the role of intermolecular interactions, providing new perspectives in the study of the intrinsic physical properties of ZnTPP crystals.

Supramolecular assemblies of phenolic metalloporphyrins: Structures and electrochemical studies

The reactivity of two phenolic porphyrins bearing respectively catechol and gallol-derived meso substituents (5,10,15,20-tetrakis(3,4-dihydroxyphenyl)porphyrin and 5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin) with trivalent metallic ions (Fe, Mn, In) was studied. Six supramolecular compounds were obtained and structurally characterized by single crystal X-ray diffraction. In each compound, the supramolecular assembly was based on the axial coordination of a phenolate function to the metallic ion lying in the porphyrinic core. A great diversity of supramolecular architectures was accessible through such simple arrangements, and objects ranging from dimers to one-dimensional polymers were isolated. Some of these assemblies were further investigated in solution by mass spectrometry and by UV-vis absorption spectroscopy. For the iron-based materials, the redox behavior was studied in solution through cyclic voltammetry experiments in inert conditions and under air.

Gas Sensors Based on Nano/Microstructured Organic Field-Effect Transistors

Benefiting from the advantages of organic field-effect transistors (OFETs), including synthetic versatility of organic molecular design and environmental sensitivity, gas sensors based on OFETs have drawn much attention in recent years. Potential applications focus on the detection of specific gas species such as explosive, toxic gases, or volatile organic compounds (VOCs) that play vital roles in environmental monitoring, industrial manufacturing, smart health care, food security, and national defense. To achieve high sensitivity, selectivity, and ambient stability with rapid response and recovery speed, the regulation and adjustment of the nano/microstructure of the organic semiconductor (OSC) layer has proven to be an effective strategy. Here, the progress of OFET gas sensors with nano/microstructure is selectively presented. Devices based on OSC films one dimensional (1D) single crystal nanowires, nanorods, and nanofibers are introduced. Then, devices based on two dimensional (2D) and ultrathin OSC films, fabricated by methods such as thermal evaporation, dip-coating, spin-coating, and solution-shearing methods are presented, followed by an introduction of porous OFET sensors. Additionally, the applications of nanostructured receptors in OFET sensors are given. Finally, an outlook in view of the current research state is presented and eight further challenges for gas sensors based on OFETs are suggested.

Controlling the supramolecular polymerization and metallogel formation of Pt(ii) complexes via delicate tuning of non-covalent interactions

Direct influence of noncovalent ionic and hydrogen bonding interactions on supramolecular polymerization mechanisms and their impact on gel formation of luminescent platinum complexes have been comprehensively investigated.

Air–water interfacial assembly of all-aromatic-substituted double-decker phthalocyanine forms aligned nanoparticles

In this manuscript, unexpected supramolecular assembly of [Formula: see text]-conjugated molecules containing complex aromatic substituents was investigated. The air–water interfacial assembly of double-decker phthalocyanines containing sixteen phenol substituents (Ce(Pc2)[Formula: see text] and Y(Pc2)[Formula: see text] form aligned nanoparticles. Depending on the different surface pressure, the Ce(Pc2)[Formula: see text] self-assembled nanostructures can be regulated thoroughly. Although Ce(Pc2)[Formula: see text] and Y(Pc2)[Formula: see text] have only aromatic substituent groups, no H- or J-aggregation of [Formula: see text]-conjugated systems can be detected from the UV-vis spectra of the assemblies of these double-decker phthalocyanines. When the nanostructures of these assemblies were changed greatly, no corresponding changes of UV-vis spectra and FT-IR spectra could be detected. These unusual results can be understood from the balance between the hydrophilicity of aromatic substituents and the ether linkages of double-decker phthalocyanines and the surface pressure, and open new. approaches for supramolecular assembly of complex [Formula: see text]-conjugated systems.

Stimuli-triggered reversible switching mechanism between H- and J-type supramolecular assemblies of cationic porphyrins adsorbed on tungsten(VI) oxide surface

Supramolecular organic dye–inorganic semiconductor nanocrystal assemblies are potentially useful in a broad range of technologies and applications, including photovoltaic systems, but the molecular basis of the adsorption of dye molecules onto the semiconductor surfaces remains poorly understood. Herein, we investigated the pH-dependent adsorption and conformational change of two cationic porphyrin stereoisomers [5,10-diphenyl-15,20-di([Formula: see text]-methyl-4-pyridyl)porphyrin (cis-DMPyP) and 5,15-diphenyl-10,20-di([Formula: see text]-methyl-4-pyridyl)porphyrin (trans-DMPyP)] on the tungsten(VI) oxide (WO[Formula: see text] colloid nanoparticle in aqueous media by means of UV-vis absorption spectroscopy. In accordance with the combination of a modified Langmuir adsorption model and Kasha’s exciton coupling model, the molecular orientation and stacking arrangement of DMPyP derivatives on the WO[Formula: see text] colloid surface are discussed in detail. In the trans-DMPyP/WO[Formula: see text] aqueous system, trans-DMPyP molecules adopted flat-on orientation with respect to the WO[Formula: see text] colloid surface and eventually formed head-to-tail [Formula: see text]-dimers regardless of pH conditions. cis-DMPyP molecules in the acidic system also lay flat-on and mainly formed [Formula: see text]-dimers on the WO[Formula: see text] colloid surface, whereas ones in the neutral system exhibited a dominant edge-on orientation and had a higher tendency to form face-to-face [Formula: see text]-dimers. Additionally, we have also convincingly demonstrated the pH-triggered switchable [Formula: see text]-stacking geometry of cis-DMPyP molecules from [Formula: see text]- to [Formula: see text]-dimer and vice versa on the WO[Formula: see text] colloid surface. Such findings will undoubtedly provide a pertinent guideline for the rational design of stimuli-responsive organic-inorganic materials.

Strategies for Improving the Performance of Sensors Based on Organic Field-Effect Transistors

Organic semiconductors (OSCs) have been extensively studied as sensing channel materials in field-effect transistors due to their unique charge transport properties. Stimulation caused by its environmental conditions can readily change the charge-carrier density and mobility of OSCs. Organic field-effect transistors (OFETs) can act as both signal transducers and signal amplifiers, which greatly simplifies the device structure. Over the past decades, various sensors based on OFETs have been developed, including physical sensors, chemical sensors, biosensors, and integrated sensor arrays with advanced functionalities. However, the performance of OFET-based sensors still needs to be improved to meet the requirements from various practical applications, such as high sensitivity, high selectivity, and rapid response speed. Tailoring molecular structures and micro/nanofilm structures of OSCs is a vital strategy for achieving better sensing performance. Modification of the dielectric layer and the semiconductor/dielectric interface is another approach for improving the sensor performance. Moreover, advanced sensory functionalities have been achieved by developing integrated device arrays. Here, a brief review of strategies used for improving the performance of OFET sensors is presented, which is expected to inspire and provide guidance for the design of future OFET sensors for various specific and practical applications.

Platinized spherical supramolecular nanoassemblies of a porphyrin: facile synthesis and excellent catalytic recyclability

Porphyrin-based supramolecular nanoassemblies of a spherical morphology have been attracting broad interest owing to their wide application possibilities in numerous fields of paramount significance. Most of the existing assembly protocols, however, either suffer from the requirement of elaborately-designed yet tediously-synthesized ad hoc porphyrins, the use of surfactant templates, or accurate consideration of the experimental parameters etc. The initiation of a facile surfactant-free fabrication protocol performable under ambient conditions using commercial porphyrins as building blocks is strongly desired. We herein report that a commercial metal-free porphyrins, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TPPNH2), could be facilely organized to form well-defined discrete spherical nanoassemblies at room temperature by means of a simple reprecipitation method. We further find that the as-manufactured TPPNH2 nanospheres could work as photocatalysts towards the reduction of potassium tetrachloroplatinate(ii), leading to their self-platinization and the production of platinum/porphyrin nanosphere nanocomposites, wherein ultrathin Pt nanoparticles of a size of ca. 3 nm are immobilized on the porphyrin nanospheres. Significantly, by taking the advantage of their easy sedimentation from aqueous suspensions, we show that the as-produced composites could serve as qualified heterogeneous nanocatalysts in terms of their excellent catalytic stability and recyclability towards the reduction of 4-nitrophenol, where the catalytic reactivity exhibits only trivial changes even after the reactions have been repeated 8 times continuously. Taking into account the general concerns of porphyrins- and Pt-based nanostructures, this might provide a facile method for the construction of spherical porphyrin nanostructures with self-platinization capability. Meanwhile, considering the high cost and scarcity of Pt, our nanocomposites with excellent stability and recyclability likely have a bright future of potential uses.

Aggregation and metal-complexation behaviour of THPP porphyrin in ethanol/water solutions as function of pH

The effect of pH change on 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (THPP) with its aggregation as function of water-ethanol mixture was studied with UV-vis, fluorescence, Raman and computational analysis. In neutral pH, THPP was present as free-base and, increasing the water amount, aggregation occurred with the formation of H- and J-aggregates. The aggregation constant and the concentration of dimers were calculated, other information about the dimer aggregation were evaluated by computational study. In acidic pH, by the insertions of two hydrogens in the porphyrin rings, the porphyrin changed its geometry with a ring deformation confirmed by red-shifted spectrum and quenching in fluorescence; at this low pH, increasing the water amount, the acidic form (THPPH₂)²⁺ resulted more stable due to a polar environment with stronger interaction by hydrogen bonding. In basic pH, reached by NH₄OH, THPP porphyrin was able to react with alkali metals in order to form sitting-atop complex (M₂THPP) confirmed by the typical absorption spectrum of metallo-porphyrin, Raman spectroscopy and by computational analysis.

Porphyrins in troubled times: a spotlight on porphyrins and their metal complexes for explosives testing and CBRN defense

A critical perspective on (metallo)porphyrins in security-related applications: the past, present and future of explosives detection, CBRN defense, and beyond.

Fabrication of carbon nanotube-multiporphyrin array composites as light-sensitizer for photocurrent generation, photochromism of viologen and catalytic degradation of methyl orange

Multiporphyrin arrays were assembled on the surface of MWNTs to produce light-sensitive nano-composites with improved opto-electric conversion efficiency, photochromic, and photocatalytic performance.

Shape-Controlled Metal-Free Catalysts: Facet-Sensitive Catalytic Activity Induced by the Arrangement Pattern of Noncovalent Supramolecular Chains

Metal-free catalytic materials have recently received broad attention as promising alternatives to metal-involved catalysts. This is owing to their inherent capability to overcome the inevitable limitations of metal-involved catalysts, such as high sensitivity to poisoning, the limited reserves, high cost and scarcity of metals (especially noble metals), etc. However, the lack of shape-controlled metal-free catalysts with well-defined facets is a formidable bottleneck limiting our understandings on the underlying structure-activity relationship at atomic/molecular level, which thereby restrains their rational design. Here, we report that catalytically active crystals of a porphyrin, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, could be shaped into well-defined cubes and sheet-like tetradecahedrons (TDHD), which are exclusively and predominantly enclosed by {101} and {001} facets, respectively. Fascinatingly, compared to the cubes, the TDHDs display substantially enhanced catalytic activity toward water decontamination under visible-light irradiation, although both the architectures have identical crystalline structure. We disclose that such interesting shape-sensitive catalytic activity is ascribed to the distinct spatial separation efficiency of photogenerated electrons and holes induced by single-channel and multichannel charge transport pathways along noncovalent supramolecular chains, which are arranged as parallel-aligned and 2D network patterns, respectively. Our findings provide an ideal scientific platform to guide the rational design of next-generation metal-free catalysts of desired catalytic performances.

Fabrication of a Highly Sensitive Single Aligned TiO2 and Gold Nanoparticle Embedded TiO2 Nano-Fiber Gas Sensor

In this research, a single-aligned nanofiber of pure TiO₂ and gold nanoparticle (GNP)-TiO₂ were fabricated using a novel electro-spinning procedure equipped with secondary electrostatic fields on highly sharp triangular and rectangular electrodes provided for gas sensing applications. The sol used for spinning nanofiber consisted of titanium tetraisopropoxide (C₁₂H₂₈O₄Ti), acetic acid (CH₃COOH), ethanol (C₂H₅OH), polyvinylpyrrolidone (PVP), and gold nanoparticle solution. FE-SEM, TEM, and XRD were used to characterize the single nanofiber. In triangular electrodes, the electrostatic voltage for aligning single nanofiber between electrodes depends on the angle tip of the electrode, which was around 1.4-2.1, 2-2.9, and 3.2-4.1 kV for 30°, 45°, and 60°, respectively. However, by changing the shape of the electrodes to rectangular samples and by increasing distance between electrodes from 100 to 200 μm, electro-spinning applied voltage decreased. Response of pure TiO₂ single nanofiber sensor was measured for 30-200 ppb carbon monoxide gas. The triangular sample revealed better response and lower threshold than the rectangular sample. Adding appropriate amounts of GNP decreased the operating temperature and increased the responses. CO concentration threshold for the pure TiO₂ and GNP-TiO₂ triangular samples was about 5 ppb and 700 ppt, respectively.

Distance-Dependent Measurements of the Conductance of Porphyrin Nanorods Studied with Conductive Probe Atomic Force Microscopy

Protocols for nanopatterning porphyrins on Au(111) were developed based on immersion particle lithography. Porphyrins with and without a central metal ion, 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP) and 5,10,15,20-tetraphenyl-21H,23H-porphyrin cobalt(II) (CoTPP), were selected for study, which spontaneously formed nanorod geometries depending on concentration parameters. The elongated shapes of the nanorods offers an opportunity for successive distance-dependent conductive probe atomic force microscopy (CP-AFM) measurements along the length of the nanorods. To prepare patterns of TPP and CoTPP nanorods, a mask of silica mesospheres was placed on gold substrates to generate nanoholes within an alkanethiol matrix film. The nanoholes prepared by particle lithography with an immersion step were backfilled with porphyrins by a second immersion step. By controlling the concentration and immersion interval, nanorods of porphyrins were generated with one end of the nanostructure attached to gold within a nanohole. The porphyrin nanorods exhibited slight differences in dimensions at the nanoscale to enable size-dependent measurements of conductive properties. The conductivity along the horizontal direction of the nanorods was evaluated with CP-AFM studies. Changes in conductivity were measured along the long axis of TPP and CoTPP nanorods. The TPP nanorods exhibited conductive profiles of an insulating material, and the CoTPP nanorods exhibited profiles of a semiconductor. The experiments demonstrate the applicability of particle lithography for preparing unique and functional surface platforms of porphyrins to measure distance-dependent conductive properties on gold.

Luminescence emission-modulated based on specific two-photon compound of triazole-conjugated pyrene derivative

A two-photon absorption compound based on triazole-conjugated pyrene derivative was synthesized, and its tunable emission was investigated.

Supramolecular porphyrin-based metal–organic frameworks: Cu(ii) naphthoate–Cu(ii) tetrapyridyl porphine structures exhibiting selective CO2/N2 separation

Porphyrin-based MOFs with copper acetate or copper 1-naphthoate exhibit different pore structure and unique CO₂/N₂ selectivity.

Porphyrinoids for Chemical Sensor Applications

Porphyrins and related macrocycles have been intensively exploited as sensing materials in chemical sensors, since in these devices they mimic most of their biological functions, such as reversible binding, catalytic activation, and optical changes. Such a magnificent bouquet of properties allows applying porphyrin derivatives to different transducers, ranging from nanogravimetric to optical devices, also enabling the realization of multifunctional chemical sensors, in which multiple transduction mechanisms are applied to the same sensing layer. Potential applications are further expanded through sensor arrays, where cross-selective sensing layers can be applied for the analysis of complex chemical matrices. The possibility of finely tuning the macrocycle properties by synthetic modification of the different components of the porphyrin ring, such as peripheral substituents, molecular skeleton, coordinated metal, allows creating a vast library of porphyrinoid-based sensing layers. From among these, one can select optimal arrays for a particular application. This feature is particularly suitable for sensor array applications, where cross-selective receptors are required. This Review briefly describes chemical sensor principles. The main part of the Review is divided into two sections, describing the porphyrin-based devices devoted to the detection of gaseous or liquid samples, according to the corresponding transduction mechanism. Although most devices are based on porphyrin derivatives, seminal examples of the application of corroles or other porphyrin analogues are evidenced in dedicated sections.

Chemical Self-Doping of Organic Nanoribbons for High Conductivity and Potential Application as Chemiresistive Sensor

Intrinsically low electrical conductivity of organic semiconductors hinders their further development into practical electronic devices. Herein, we report on an efficient chemical self-doping to increase the conductivity through one-dimensional stacking arrangement of electron donor-acceptor (D-A) molecules. The D-A molecule employed was a 1-methylpiperidine-substituted perylene tetracarboxylic diimide (MP-PTCDI), of which the methylpiperidine moiety is a strong electron donor, and can form a charge transfer complex with PTCDI (acting as the acceptor), generating anionic radical of PTCDI as evidenced in molecular solutions. Upon self-assembling into nanoribbons through columnar π-π stacking, the intermolecular charge transfer interaction between methylpiperidine and PTCDI would be enhanced, and the electrons generated are delocalized along the π-π stacking of PTCDIs, leading to enhancement in conductivity. The conductive fiber materials thus produced can potentially be used as chemiresistive sensor for vapor detection of electron deficient chemicals such as hydrogen peroxide, taking advantage of the large surface area of nanofibers. As a major component of improvised explosives, hydrogen peroxide remains a critical signature chemical for public safety screening and monitoring.

Perylenetetracarboxylic-metal assemblies and anisotropic charge transport in a Cu(II) assembly

Structural diversity and uniformity of nanomaterials are usually prerequisites for many practical applications involving the oriented fabrication of various devices with full control over their desired physiochemical properties. Particularly in the optoelectronic field, ordered assembly inside cells is required not only for obtaining attractive configurations but also for playing an important role in the characteristics of photoconduction and conductivity. Here, we present a synergetic self-assembly driven by coordination and intermolecular interactions for the construction of organic-inorganic hybrids with multi-morphologies and tunable physical properties. 3,4,9,10-Perylenetetracarboxylic dianhydride was treated with base to produce various assemblies by coordination with metal ions, showing morphologies of nanowires, nanosheets, nanoribbons and nanorods. The organic π-spacer affords an extension in different directions through the suitable incorporation of metal ions with different coordination modes for the formation of metal-ligand complexes. Interestingly, the obtained nanorods were twisted rods with obvious screw threads on the rod wall, supporting the synergetic self-assembly. Then, anisotropic mobility measurements of the obtained Cu(2+)-ligand assembly were carried out to show the importance of the size- and shape-confined synthesis of the hybrids. By presenting a series of ordered metal-ligand complex superstructures driven by synergetic self-assembly, this work is expected to pave the way for future anisotropic measurements of complex assemblies.

Fully Integrated Organic Nanocrystal Diode as High Performance Room Temperature NO2 Sensor

Organic diodes consisting of molecular nano-pyramid structures sandwiched between metal and strained nano-membrane electrodes are created. The robust and smooth contacts provided by self-curled metal layers render the molecular nano-pyramids efficent channels for detecting nitrogen dioxide airflow.

Mussel inspired locomotive: the moisture induced actuation in a poly(vinyl alcohol) film containing melanin-like dopamine nano spheres

We report here for the first time a PVA film incorporated with PDNs that is capable of fast and perpetual motion driven by a humidity gradient.

Primary investigation of the optical limiting performance of cyclo[8]pyrrole with a wide optical limiting window

Cyclo[8]pyrrole (CP) was prepared and its UV/vis spectral and optical limiting properties for ns light pulse were investigated withZ-scan technical.

Porphyrin Supramolecular 1D Structures via Surfactant-Assisted Self-Assembly

One-dimensional (1D) solid-state supramolecular structures based on porphyrin chromophores arouse numerous expectations from the interdisciplinary scientific communities of supramolecular chemistry and advanced soft materials science. This stems from the intrinsic assembly capability of porphyrins to form various well-defined 1D assemblies, which have broad opportunities in the fields of advanced soft matter. A brief review on 1D porphyrin micro-/nanoassemblies constructed via surfactant-assisted self-assembly is presented here, in terms of addressing new ideas recently developed for controlled assembly, hierarchical organization, and new-type functional surfactants etc. The functionalization of the as-assembled 1D structures with regard to supramolecular photocatalysis, non-linear optics, nanoelectronic gas sensors, photoelectrochemical solar cells, etc. is highlighted.

Water Dispersible and Biocompatible Porphyrin-Based Nanospheres for Biophotonics Applications: A Novel Surfactant and Polyelectrolyte-Based Fabrication Strategy for Modifying Hydrophobic Porphyrins

The hydrophobility of most porphyrin and porphyrin derivatives has limited their applications in medicine and biology. Herein, we developed a novel and general strategy for the design of porphyrin nanospheres with good biocompatibility and water dispersibility for biological applications using hydrophobic porphyrins. In order to display the generality of the method, we used two hydrophobic porphyrin isomers as starting material which have different structures confirmed by an X-ray technique. The porphyrin nanospheres were fabricated through two main steps. First, the uniform porphyrin nanospheres stabilized by surfactant were prepared by an interfacially driven microemulsion method, and then the layer-by-layer method was used for the synthesis of polyelectrolyte-coated porphyrin nanospheres to reduce the toxicity of the surfactant as well as improve the biocompatibility of the nanospheres. The newly fabricated porphyrin nanospheres were characterized by TEM techniques, the electronic absorption spectra, photoluminescence emission spectra, dynamic light scattering, and cytotoxicity examination. The resulting nanospheres demonstrated good biocompatibility, excellent water dispersibility and low toxicity. In order to show their application in biophotonics, these porphyrin nanospheres were successfully applied in targeted living cancer cell imaging. The results showed an effective method had been explored to prepare water dispersible and highly stable porphyrin nanomaterial for biophotonics applications using hydrophobic porphyrin. The approach we reported shows obvious flexibility because the surfactants and polyelectrolytes can be optionally selected in accordance with the characteristics of the hydrophobic material. This strategy will expand the applications of hydrophobic porphyrins owning excellent properties in medicine and biology.

Aggregation behavior of tetraphenylporphyrin in aqueous surfactant solutions: Chiral premicellar J-aggregate formation

Porphyrin-surfactant interactions in aqueous solutions are known to result in the selfassembly of various supramolecular structures, including pigment-surfactant complexes, J- and H-aggregates, and solubilized dye species. Detailed studies on the mechanisms of the intermolecular interactions governing the above self-assembly processes allow to predict the aggregation state and hence, the photophysical properties of the dye-surfactant assemblies in order to perform a direct synthesis of the desired porphyrin-based nanostructures at the appropriate experimental conditions. This paper describes a novel example of the surfactant-induced J-aggregate formation from the diprotonated hydrophobic tetraphenylporphyrin species in submicellar aqueous anionic surfactant solutions. The above assemblies are characterized by a rod-like morphology and possess supramolecular chirality according to the CD measurements.

Morphology-controlled self-assembly of an organic/inorganic hybrid porphyrin derivative containing polyhedral oligomeric silsesquioxane (POSS)

An organic/inorganic hybrid porphyrin derivative, namely, metal-free tetrakisphenyl porphyrin-polyhedral oligomeric silsesquioxanes (H2 TPP-POSS) was synthesized by azide-alkyne click chemistry. The self-assembly behavior of H2 TPP-POSS was systematically studied in CHCl3 at different concentrations and in solvents with different polarities. Novel nanovesicles could be obtained through the self-assembly of H2 TPP-POSS in CHCl3 at a concentration lower than 10(-4)  m. Diffuse microrods formed at a concentration higher than 10(-4)  M. Additionally, the polarity of the solvent also greatly influenced the assembled morphologies, and a series of assembled morphologies, including crescent-shaped micelles, spherical micelles, doughnut-shaped vesicles, and ordered square sheets, could form in solvents with different polarities.

Reactive and ‘clickable’ electrospun polymeric nanofibers

This mini-review summarizes the design, synthesis and modification of various reactive and ‘clickable’ electrospun polymeric nanofibers to render them functional.

A general protocol for π-conjugated molecule-based micro/nanospheres: artificial supramolecular antenna in terms of heterogeneous photocatalysis

An oil-in-water-mediated surfactant-assisted assembly is initiated as a general method for π-conjugated molecules-based micro/nanospheres, supramolecular antenna with regard to heterogeneous photocatalysis has been realized using porphyrin spheres.

Controllable self-assemblies of sodium benzoate in different solvent environments

Sodium benzoate is an important and widely used food additive, however, it's self-assembly properties in diverse solvents have been rarely studied. Here, we systematically report its various self-assemblies in different solvents environments.