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Achieving organic room-temperature phosphorescence (RTP) in a solvent-free liquid state is a challenging task because the liquid state provides a less rigid environment than the crystal. Here, we report that an unsymmetrical heteroaromatic 1,2-diketone forms an organic RTP liquid. This diketone exists as a kinetically stable supercooled liquid, which resists crystallisation even under pricking or shearing stresses, and remains as a liquid for several months. The unsymmetrical diketone core is flexible, with eight distinct conformers possible, which prevents nucleation and growth for the liquid–solid transition. Interestingly, the thermodynamically stable crystalline solid-state was non-emissive. Thus, the RTP of the diketone was found to be liquiefaction-induced. Single-crystal X-ray structure analysis revealed that the diminished RTP of the crystal is due to insufficient intermolecular interactions and restricted access to an emissive conformer. Our work demonstrates that flexible unsymmetrical skeletons are promising motifs for bistable liquid–solid molecular systems, which are useful for the further development of stimuli-responsive materials that use phase transitions., Metal-free, single-component, unsymmetrical 1,2-diketone exhibits liquefaction-induced room-temperature phosphorescence. Desymmetrisation provides the supercooled liquid with notable kinetic stability and phase-dependent phosphorescence properties.

Crystal melting by light irradiation, that is, the phenomenon of photoinduced crystal-melt transition (PCMT), can dramatically change material properties with high spatiotemporal resolution. However, both the process and mechanism of PCMT remain unknown owing to a lack of suitable probes and the poor diversity of compounds exhibiting PCMT. Here, we report the first instance of PCMT with luminescence evolution. We show that a heteroaromatic 1,2-diketone crystal exhibits ON-OFF-ON luminescence changes under continuous ultraviolet irradiation, which can be ascribed to the sequential PCMT processes of crystal loosening and conformational isomerization before macroscopic melting. Single-crystal X-ray structural analysis, thermal analysis, and theoretical calculations of three diketones revealed that weak intermolecular interactions and the presence of a disordered layer in the crystal are essential for PCMT. Our results provide fundamental insights into the melting process of molecular crystals and should aid the molecular design of PCMT-active materials that are based on emissive compounds, as opposed to the classical molecular designing based on nonemissive photochromic scaffolds such as azobenzenes.

Isophlorins (two-electron-reduced porphyrins) with 20π antiaromaticity have been synthesized by metallation or core modification (replacing the inner NHs with less bulky atoms) thus far. The core-modification number (CMN) is an important factor for the stability of isophlorins against their oxidation to porphyrins. However, isophlorins with small CMN (≤ 2), i.e., without significant core modification, are difficult to synthesize and important for understanding their structure–antiaromaticity relationships. Herein, we report the synthesis of free-base (metal-free) antiaromatic isophlorins with no core modification (CMN=0) for the first time in the literature. β-Tetracyanoporphyrins were successfully reduced by hydrazine to their corresponding isophlorins under aerobic conditions. These porphyrin/isophlorin transformations are reversible. Their structure and antiaromaticity were studied via 1H NMR and UV-vis/near-infrared absorption spectroscopy, X-ray diffraction and theoretical calculations.

Aggregation-induced emission (AIE) has attracted considerable attention, and many types of molecules have been reported to show AIE. However, fully fused polycyclic π-systems remain unexplored as AIE luminogens because non-flexible structures are not suitable for AIE. Herein, we report a structure–AIE property relationship in a series of benzo- and/or thieno-fused pyrano[3,2-b]pyran-2,6-dione (PPD) derivatives. Although the π-conjugated skeleton is fully ring-fused and thus rigid, the benzo-fused PPDs exhibit AIE, while the bis-thieno-fused PPDs result in fluorescence quenching in the crystal. Notably, these contrasting behaviours do not depend on the substituents but on the peripheral fused aromatic rings, which does not follow the intuition that AIE is controlled by molecular flexibility. Vibrational analysis and investigation of photophysical rate constants revealed that in the benzo-fused PPDs the pyrone CO stretching vibrations are coupled strongly with the nonradiative decay, enabling AIE activity of the rigid skeleton. This coupling is not pronounced in the bis-thieno-fused analogues, demonstrating that the rigid skeleton can be AIE active through vibronic control. Our work reveals a way to integrate the wide application area of AIE with the promising optoelectronic functions of polycyclic fused π-systems.

The realization of molecular devices via metal–molecule–metal junctions necessitates the fabrication of a steady molecular bridging structure, where the number of bridging structures should be fixe...

We study the spin state of the π radical assemblies, which are created through converting nonmagnetic terbium (2,3,7,8,12,13,17,18-octaethylporphyrinate) (2,3,7,8,12,13,17,18-octaethylporphyrindiat...

Facile redox-induced aromatic-antiaromatic interconversions were accomplished by using β-tetracyano-21,23-dithiaporphyrin (CN4 S2 Por). Introduced cyano groups not only increased the reduction potential of the porphyrin core but also stabilized the antiaromatic isophlorin (CN4 S2 Iph) by π conjugation. The reduction of CN4 S2 Por with hydrazine in polar solvents quantitatively affords CN4 S2 Iph, even under ambient conditions. CN4 S2 Iph retains a nearly planar conformation and exhibits considerable antiaromaticity. Aerobic oxidation of CN4 S2 Iph to CN4 S2 Por occurs in nonpolar solvents. This study was conducted to contribute to the understanding of the structure-antiaromaticity relationship.

Single-crystal X-ray crystallographic analyses of two kinds of [tetraarylporphyrin]22+/[polyoxomatalate]4− (POM, SV2W10O40) complexes showed that the porphyrin and POM make three-dimensional polymeric structures, and no discrete molecular structure of [porphyrin]2[POM] units was identified. Although the two components (porphyrin and POM) can be dissociated in solution, thin films made by casting the solution partially retained the crystallographic structure, as judged from the reflection spectra and X-ray powder diffraction. A thin film of the complex between electrodes with a gap of 2 μm showed good conductivity, whereas the porphyrin and POM components separately measured under the same conditions were insulating. The I–V curves of the complex showed negative differential resistance (NDR), which can be explained by (1) conduction switching at a certain bias voltage and (2) the slow response of the conductance switching in the voltage scan time range. The increased conduction at a higher bias voltage was confirmed by AC impedance spectrometry. This is a new proposal for a mechanism of NDR phenomena.

Metal-free single component liquid, developed by desymmetrizing C2-symmetrical diketone, exhibits room-temperature phosphorescence (RTP) and phosphorescent thermochromism in air. The unsymmetrical flexible core with as many as eight conformers kinetically stabilizes the supercooled liquid state. The RTP is unique the liquid that benefits from external heavy atom effect and suppresses oxygen diffusion, while produces an emissive conformer.

In this study, organic solvent-dispersible nanoparticles of an FeII-1,2,4-triazole spin-crossover complex were synthesized. On mixing the suspension of the spin-crossover nanoparticles with a solution of single-walled carbon nanotubes (SWCNTs), the nanoparticles were strongly adsorbed on the hydrophobic SWCNT bundles, resulting in hybrid network structures. Variable temperature DC electrical conductivity measurements of the hybrid network thin films demonstrated that the conductivities of the composite films were switched by the spin transition of the nanoparticles.

An organic 1,2-diketone, which exhibits color change of room-temperature phosphorescence (RTP) upon mechanical stimulation, is reported. Experimental and theoretical investigations revealed that this mechanochromism is based on a molecular rotational isomerization associated with a crystalline-to-amorphous transition. In general, amorphization weakens intermolecular interactions, resulting in RTP quenching. In contrast, the present diketone shows an even higher phosphorescence quantum yield after amorphization, representing the first RTP-to-RTP mechanochromism of a metal-free organic molecule. We have disclosed that a planar conformer of the diketone, which is responsible for the RTP in the amorphous state, involves intramolecular chalcogen bonding. Having this noncovalent interaction, the diketone would be a promising platform for the design of mechanochromic and RTP-active organic materials; flexible enough for a large conformational change, while rigid enough to exhibit efficient RTP in the amorphous state.

This work mainly reports the observation of novel supramolecular structures of TbIII-5,15-bisdodecylporphyrin (BDP, C12P) double-decker complexes on the surfaces of single-walled carbon nanotubes (SWNTs) performed by scanning tunneling microscopy under an ultra-high vacuum and low temperature, atomic force microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy, and ultraviolet-visible spectroscopy. The molecules formed a well-ordered self-assembled helix-shaped array with regular periodicity on the tube surface. Additionally, some magnetic properties of the BDP-molecule as well as the resulting BDP-SWNT composites were investigated by superconducting quantum interference measurements. The molecule exhibits single-molecule magnetic (SMM) properties and the composite's magnetization increases almost linearly with decreasing temperature which is possibly due to the coupling between porphyrin molecules and SWNTs. Consequently, this may enable the development of more advanced spintronic devices based on porphyrin-nanocarbon composites.

Supramolecular structures of organic molecules on planar nanocarbon surfaces, such as highly oriented pyrolytic graphite (HOPG), have been extensively studied and the factors that control them are generally well-established. In contrast, the properties of supramolecular structures on curved nanocarbon surfaces like carbon nanotubes remain challenging to predict and/or to understand. This paper reports an investigation into the first study of the supramolecular structures of 5,15-bisdodecylporphyrin (C12P) on chiral, concentrated single-walled carbon nanotubes (SWNTs; with right-handed helix P- and left-handed helix M-) surfaces using STM. Furthermore, the study is the first of its kind to experimentally assign the absolute-handedness chirality of SWNTs, as well as to understand their effect on the supramolecular structures of organic molecules on their surfaces. Interestingly, these SWNT enantiomers resulted in supramolecular structures of opposite chirality based on the handedness chirality. With molecular modelling, we predicted the absolute-handedness chirality of SWNTs, before demonstrating this experimentally.

In this study, supramolecular structures of metalloporphyrin derivatives, i.e., Zn, Co, and Ni on a single-walled carbon nanotube (SWNT) surface have been investigated using microscopic and spectroscopic measurements as well as density functional theory calculations, to identify the effect of metalation on the supramolecular structures of porphyrins on a curved carbon surface (SWNT). By changing the central metal incorporated inside the porphyrin ring, different supramolecular structures can be observed on the SWNT surface using scanning tunneling microscopy, which displays the effect of different metal centers on the supramolecular structure. Although predicting or understanding supramolecular structures on the SWNT surfaces is still a big challenge, this study will serve as a helpful key point for further understanding, building new supramolecular architectures on SWNT surfaces and designing novel molecular architectonics of porphyrin/SWNTs-based devices.

Copper- and nickel-porphyrin complexes show extremely weak axial coordination ability without any electron-withdrawing groups. Herein, we report axial ligation on CuII- and NiII-porphyrins in a highly rigid cofacial porphyrin dimer with a bidentate ligand, 1,4-diazabicyclo[2.2.2]octane (DABCO). To the best of our knowledge, this is the first report on the use of CuII- and NiII-porphyrins for coordination-induced guest binding of porphyrin-based host molecules without the help of other metal ions. The high rigidity of the dimer induces guest binding through the cooperative effect of weak axial ligation. The results showed that CuII- and ZnII-complexes bind one DABCO molecule inside their cavities, whereas the NiII-complex binds two additional DABCO molecules outside to form a stable 6-coordinate paramagnetic NiII-complexes.

The room-temperature phosphorescence (RTP) of metal-free organic crystals is normally quenched by mechanical stimulation. Herein, we demonstrate the opposite mechanoresponse of turn-on RTP. A desymmetrization of a C2-symmetric 1,2-diketone creates space for molecular motion in the crystal, quenching the RTP from the crystal while maintaining that from the amorphous solid.

Replacing von-Neumann architecture with walled carbon nanotube (SWNT) with new neuromorphic chips is vital for computers to perform polyoxometalate POM) ion ([SV2W10O40]H4TPP) complex cognitive problem with low power and see the effect of higher POM concentration. We consume like our brain. The synaptic part of the use simple sonication method for SWNT/POM brain has been well studied via memristors but fabrication and study the spiking and spike time research on the artificial neurons is only limited to high interval behavior via electrical measurements. The power CMOS circuitry. Following the previous work, results show that the device can behave as an artificial by H. Tanaka et al.[2] herein we functionalize single neuron even at low voltages and hence can be used for low power neuromorphic computing., Proceedings of International Symposium on Applied Science 2019 (ISAS),18-19 October, 2019, Ho Chi Minh City University of Technology, Ho Chi Minh City, Vietnam

Compound 5,15-diphenyl porphyrin (DPP) has been synthesized and inserted with different kind of metal (Fe, Cu and Zn). Synthesis of DPP has been carried out through three stages reaction using pyrrole and benzaldehyde as starting materials. Identification of synthesized compounds of 5-phenyl dipyrromethane (DPM) and 5, 15-diphenyl porphyrin (DPP) was confirmed with H-NMR. Three different metals were then inserted into the cavity of DPP. Optical spectra of Cu, Fe, Zn-DPP was then investigated and compared with free-base DPP using UV/Vis spectrophotometer. The result showed that the yield reaction of DPM reached about 41.77% and DPP reached about 21.80%. Based on the spectra investigation of metal-DPP, it showed that DPP had different Soret and Q band when each Cu (II), Fe (II), Zn (II) was inserted into DPP. Moreover, Zn-DPP has Q band at to the rightest shifting than Cu-DPP or Fe-DPP which means it has the least excitation energy among them. Therefore, Zn-DPP has the more potential to be utilized for application such as DSSC.

The original single-molecule rectifier proposed by Aviram and Ratner is based on a donor-σ-acceptor structure, in which σ functions as the insulator to disconnect the π electronic systems of the two parts. However, there have been no reports on experimentally demonstrated highly efficient single-molecule rectifiers based on this mechanism. In this paper, we demonstrate single-molecule rectifiers with perpendicularly connected metal porphyrin-imide dyads. Our proposed molecule rectifiers use hydroxyl groups at both ends as weak anchoring groups. Measurements of the single-molecule current-voltage characteristics of these molecules clearly show that the rectification ratio reached a high value of 14 on average. Moreover, the ratio could be tuned by changing the central metal in the porphyrin core. All of these features can be explained by the energy-level shift of the molecular orbital using a model with three electronic parts.

In contrast to AI hardware, neuromorphic hardware is based on neuroscience, wherein constructing both spiking neurons and their dense and complex networks is essential to obtain intelligent abilities. However, the integration density of present neuromorphic devices is much less than that of human brains. In this report, we present molecular neuromorphic devices, composed of a dynamic and extremely dense network of single-walled carbon nanotubes (SWNTs) complexed with polyoxometalate (POM). We show experimentally that the SWNT/POM network generates spontaneous spikes and noise. We propose electron-cascading models of the network consisting of heterogeneous molecular junctions that yields results in good agreement with the experimental results. Rudimentary learning ability of the network is illustrated by introducing reservoir computing, which utilises spiking dynamics and a certain degree of network complexity. These results indicate the possibility that complex functional networks can be constructed using molecular devices, and contribute to the development of neuromorphic devices., Neuromorphic hardware is based on principles of neuroscience, and has the potential to provide higher-level brain functions. Here, the authors develop a neuromorphic network device, constructed from single-walled carbon nanotubes and polyoxometalate, that mimics nerve impulse generation.

Molecular structures for three oxidation forms (anion, radical, and cation) of terbium(III) bis(porphyrinato) double-decker complexes have been systematically studied. We found that the redox state controls the azimuthal rotation angle (φ) between the two porphyrin macrocycles. For [TbIII (tpp)2 ]n (tpp: tetraphenylporphyrinato, n=-1, 0, and +1), φ decreases at each stage of the oxidation process. The decrease in φ is due to the higher steric repulsion between the phenyl rings on the porphyrin macrocycle and the β hydrogen atoms on the other porphyrin macrocycle, which results from the shorter interfacial distance between the two porphyrin macrocycles. Conversely, φ=45° for both [TbIII (oep)2 ]-1 and [TbIII (oep)2 ]0 (oep: octaethylporphyrinato), but φ=36° for [TbIII (oep)2 ]+1 . Theoretical calculations suggest that the smaller azimuthal rotation angle of the cation form is due to the electronic interaction in the doubly oxidized ligand system.

Single molecule conductance (SMC) of a series of porphyrin derivatives, whose porphyrin units are connected through a phenylene bridge that have one or two thiolate end groups, was measured by a scanning tunneling microscopic break junction (STM-BJ) technique. The observed conductance values were analyzed by partial transmission probabilities (Ti) for the molecular parts using the equation G=G0∏iNTi . Unique combination of Ti was obtained, which indicates the validity of this analysis. By the analysis, the free-base porphyrin ring interacting with the gold electrode was found to show a greater transmission probability Tpor-Au than that of the bridge between thiolate and the gold electrode (TS-Au).

This review highlights the effective design criteria for lanthanide single-molecule magnets, which show strong magnetic blocking temperature up to 60 K. Increase in the anisotropy barrier and decrease in the quantum magnetization are attainable by controlling the ligand field, local molecular symmetry related to the coordination geometry of the complex, and magnetic dipole–dipole interactions between the lanthanide ions. With recent advances in this field, a new 2-coordinate complex, which is predicted to show a blocking temperature of more than 77 K, is also introduced. The existence of a proton in the nitrogen atom of porphyrin ligands quenches the single-molecule magnet because of the destruction of the symmetry, which can be possibly overlooked because of the disorder of the position of the proton in the crystals.

This work reports confirmation of the experimental assignment of the absolute-handedness chirality of single-walled carbon nanotubes (SWNTs). This was achieved by applying the scanning tunneling microscopy (STM) imaging technique to a supramolecular composite consisting of a metalized porphyrin derivative (nickel-5,15-bisdodecylporphyrin [Ni-BDP]) affixed to the surfaces of chiral-concentrated SWNTs (with right-handed helix P- and left-handed helix M-). On the basis of the handedness chirality, different chiral supramolecular structures of Ni-BDP were observed on the surfaces of the two SWNT enantiomers. The incorporation of a metal center into the porphyrin ring did not significantly affect the SWNT absolute-handedness chirality assignment, the large pi-system porphyrin ring being the crucial factor. These findings will effectively pave the way towards the clear selective synthesis, separation, chemistry, and applications of SWNT enantiomers.

Dinuclear rare-earth (TbIII , YIII ) triple-decker complexes with a fused diporphyrin (FP) and two tetraphenylporphyrin (TPP) ligands were synthesized in neutral, dianionic, and diprotonated forms. The neutral forms have large open shell biradical character, as determined from the temperature dependency of the magnetic susceptibility measurements and theoretical calculations. The coupling value (J=-1.4 kcal mol-1 , -487 cm-1 ) of the radical centers in the neutral form of the YIII complex indicates weak pairing interactions. Theoretical calculations on the neutral form reveal a significant biradical character (y=68 %). Furthermore, the TbIII complex exhibits multi-redox states, having more than eight clear peaks in the voltammetry curves. The optical (3700 nm, 0.33 eV) and electrochemical measurements (3400 nm, 0.36 eV) indicate that the neutral form has very small HOMO-LUMO energy gap. Despite the large biradical character, the neutral complexes are thermally stable and do not decompose on heating at 120 °C. These complexes with unique characteristics are promising candidates for use in molecular electronics, optics, and spintronics.

Direct structural evidence of the presence and location of the attached proton in the protonated form of rare earth bis(porphyrinato) double-decker complexes is obtained from an X-ray diffraction study of single crystals for a series of protonated forms of bis(tetraphenylporphyrinato) complexes [M(III)(tpp)(tppH)] (M = Tb, Y, Sm, Nd, and La). When CHCl3 is used as a solvent for crystallization of the complexes, their nondisordered molecular structures are obtained and the attached proton is identified on one of the eight nitrogen atoms. Use of other solvents affords another type of crystal, in which the position of the proton is disordered and thus the molecular structure is averaged. La complex also affords the disordered average structure even when CHCl3 is used for crystallization. A variable-temperature diffraction study for the Tb complex reveals that the dynamics of the proton in the nondisordered crystal is restricted.

Non-symmetric electric properties such as rectification, negative differential resistance, threshold gate, hysteresis effect, and integrated threshold gate are essential for realizing molecular brain computer, which are believed to withstand noise and fluctuations. Thus far, there is no fixed design principle for single-molecule electronic devices, mainly because the current–voltage (I–V) characteristics of such devices differ owing to differing conduction mechanisms. In the tunneling regime of the molecules, the I–V characteristics are essentially dependent on the density of states of the system, while in the hopping mechanisms, the molecules can be charged to change their electronic characteristics. To understand the principle, we have synthesized a series of molecules to study the electric properties of single molecules.

The first step towards the synthesis of single-molecule magnet (SMM)-based spintronics devices is the organization and manipulation of magnetic molecules on surfaces. Our previous studies on bulk crystals demonstrated that protonated porphyrinato double-decker complexes [Tb(Hoep)(oep)] (oep = 2,3,7,8,12,13,17,18-octaethylporphyrinato) are not SMMs; however, once a hydrogen is removed to produce their neutral radical forms, [Tb(oep)2], they convert to SMMs. These intriguing properties encouraged us to examine the electronic/spin properties of these complexes and their chemical conversion ability after their transfer onto a metal substrate, similar to the environment required for the practical application of SMMs. Herein, we conducted a single-molecule-scale conversion of the protonated bis(porphyrinato)terbium(III) double-decker complex [Tb(Hoep)(oep)], whose hepta-coordinated terbium ion changes into octa-coordinated [Tb(oep)2] on detaching a hydrogen atom by scanning tunnelling microscopy. This conversion can be caused by the injection of tunnelling electrons of energy 1.5–2.5 eV. We confirmed the conversion by analysing the topographic image and the spin state of the molecule. The latter was achieved by examining the Kondo resonance, which originated from the screening of the molecular spin by the conduction electrons of the metal. The Kondo resonance was not observed for [Tb(Hoep)(oep)] but was observed for the converted species, which agrees well with a model containing the [Tb(oep)2] molecule and Kondo resonance originating from the π-electron spin of the porphyrin ligand. Even though it is not possible to provide complete evidence of the SMM properties of the transferred molecule, we have demonstrated a possible path to realize the switch-on SMM properties of a single molecule.

Three tobacco types (Burley, Flue Cured, and Oriental) and eight cigarette brands were unequivocally identified using an electronic nose formed by only three sensors based on a single novel conducting polymer (PF-BTB) doped with different porphyrins (H2TPP, H2TPFP, and H2BTBOP). The synthesis and characterization of the polymer are also discussed. Small changes in the porphyrin structure caused significant changes in the electrical conductance response patterns of the sensors upon exposure to complex chemical matrixes, representing a novel approach for tuning the selectivity of chemiresistive sensors for e-nose application. This e-nose is fast, cheap, reliable, can be easily operated, and could be a valuable tool for border agents fighting cigarette smuggling around the world, helping them prevent losses of millions in tax revenues and sales.

Porphyrin derivatives are potential candidates as constituents of functional molecular devices because their electronic levels can be rationally manipulated by chemical modification. In this work, we deposit a porphyrin molecule with a hydroxyphenyl side group on Au(111), which is designed and synthesized as a basic unit for functional single molecule devices, and observe the bonding structure and electronic states with scanning tunneling microscopy (STM). The molecule changes configuration from a monomer to a cluster to a monolayer as the coverage increases, ruled by the H-bonding interaction through the hydroxyphenyl group and the steric repulsion by the isopentoxy groups. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) localized in the porphyrin macrocycle are observed at −1.1 and +1.1 eV, respectively, with respect to the Fermi level. We also deposit a para-phenylene-bridged porphyrin array on the surface using the electrospray method, and observe the local density of states along the array., Accepted 03 Sep 2015

This review highlights molecular design for nonlinear and nonsymmetric single-molecule electronic properties such as rectification, negative differential resistance, and switching, which are important components of future single-molecule information processing devices. Perspectives on integrated "molecular circuits" are also provided. Nonlinear and nonsymmetric single-molecule electronics can be designed by utilizing (1) asymmetric molecular cores, (2) asymmetric anchoring groups, (3) an asymmetric junction environment, and (4) asymmetric electrode materials. This review mainly focuses on the design of molecular cores.

Detection and use of physical noise fluctuations in a signal provides significant advantages in the development of bio- and neuro-sensing and functional mimicking devices. Low-dimensional carbon nanomaterials are a good candidate for use in noise generation due to the high surface sensitivity of these materials, which may themselves serve as the main building blocks of these devices. Here, we demonstrate that the addition of a molecule with high redox activity to a carbon nanotube (CNT) field-effect transistor provides tunable current fluctuation noise. A unique charge-trap state in the vicinity of the CNT surface due to the presence of the single molecule is the origin of the noise, which generates a prominent and unique slow discrete random telegraph signal in the device current. The power spectral density reveals the peculiar frequency limit of the fluctuation for different types of molecules depending on their redox activity and adsorption configuration. These results indicate that the detected noise will provide new opportunities to obtain electronic information for a single molecule combined with a nanotube surface, and that controllability of the noise may contribute to the expansion of noise utilization in future bio-inspired devices.

In this study, a simple and fast approach of band gap formation in a single layer graphene nanoribbon (sGNR) is demonstrated by using hexaazatriphenylenehexacarbonitrile (HAT-CN6) as an adsorbate molecule. sGNRs were successfully synthesized through the unzipping of double-walled carbon nanotubes followed by casting HAT-CN6 in acetone solution to alter the electronic properties of the sGNRs. Then, the electrical property of a sGNR was measured using a field effect transistor structure and also by point-contact current imaging atomic force microscopy. The results demonstrate the formation of electron trapping sites with the nanoparticles and the neck structure of the sGNR near the adsorbed region of the molecule. Therefore, the charge carriers on the sGNR can only pass through the neck region, which works similarly to a narrow sGNR. Such a narrow sGNR has a lateral confinement of charge carriers around the neck region; hence, the device becomes semiconducting. The fabricated semiconducting sGNR could be widely used in electronic devices.

This work uncovers the application of porphyrin dimers for the use in electroanalysis, such as potentiometric determination of ions. It also puts in question a current perception of an occurrence of the super-Nernstian response, as a result of the possible dimerization of single porphyrins within an ion-selective membrane. To study that, four various porphyrin dimers were used as ionophores, namely, freebase-freebase, Zn-Zn, Zn-freebase, and freebase-Zn. Since the Zn-freebase and freebase-Zn porphyrin dimers carried both anion- and cation-sensitive porphyrin units, their application in ISEs was utilized in both anion- and cation-sensitive sensors. With respect to the lipophilic salt added, both porphyrins dimers were found anion- and cation-sensitive. This allowed using a single molecule as novel type of versatile ionophore (anion- and cation-selective), simply by varying the membrane composition. All anion-sensitive sensors were perchlorate-sensitive, while the cation-selective sensors were silver-sensitive. The selectivity of the sensors depended primarily on the porphyrin dimers in the ion-selective membrane. Furthermore, the selectivity of cation-sensitive dimer based sensors was found significantly superior to the ones measured for the single porphyrin unit based sensors (precursors of the porphyrin dimers). Thus, the dimerization of single porphyrins may actually be a factor to increase or modulate porphyrin selectivity. Moreover, in the case of cation-sensitive sensors, the selectivity vastly depended on the order of porphyrin units in the dimer. This opens a new approach of regulating and adjusting sensitivity and selectivity of the sensor through the application of complex porphyrin systems with more than one porphyrin units with mix sensitive porphyrins.

Nonsymmetric electric properties such as rectification, negative differential resistance, threshold gate, hysteresis effect, and integrated threshold gate are essential for realizing molecular brain computers, which are believed to withstand noise and fluctuations. So far, there is no fixed design principle for single-molecule electronic devices, mainly because the current–voltage (I–V) characteristics of such devices differ owing to differing conduction mechanisms. In the tunneling regime of the molecules, the I–V characteristics are essentially dependent on the density of states of the system, whereas in the hopping mechanisms, the molecules can be charged to change their electronic characteristics. To understand this principle, we have synthesized a series of molecules to study the electric properties of single molecules.

In this paper, a new composite sensor for e-nose application is described. A modification in the regular pair conductive polymer/Lewis acid dopant is proposed, replacing the acid by free-base or metallated porphyrins. Sensors doped with different porphyrin species, using the same conductive polymer, led to a huge variation in response to selected analytes. Two different arrays (doped with free-base and metallated porphyrins) using these sensors were able to identify four organic solvents, used as standard analytes: propanone, ethyl acetate, ethanol and toluene. Both of them could distinguish the tested vapours.