Molecular Material Research Articles

Fenpicoxamid-Imprinted Surface Plasmon Resonance (SPR) Sensor Based on Sulfur-Doped Graphitic Carbon Nitride and Its Application to Rice Samples.

This research attempt involved the development and utilization of a newly designed surface plasmon resonance (SPR) sensor which incorporated sulfur-doped graphitic carbon nitride (S-g-C3N4) as the molecular imprinting material. The primary objective was to employ this sensor for the quantitative analysis of Fenpicoxamid (FEN) in rice samples. The synthesis of S-g-C3N4 with excellent purity was achieved using the thermal poly-condensation approach, which adheres to the principles of green chemistry. Afterwards, UV polymerization was utilized to fabricate a surface plasmon resonance (SPR) chip imprinted with FEN, employing S-g-C3N4 as the substrate material. This process involved the inclusion of N,N'-azobisisobutyronitrile (AIBN) as the initiator, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, methacryloylamidoglutamic acid (MAGA) as the monomer, and FEN as the analyte. After successful structural analysis investigations on a surface plasmon resonance (SPR) chip utilizing S-g-C3N4, which was imprinted with FEN, a comprehensive investigation was conducted using spectroscopic, microscopic, and electrochemical techniques. Subsequently, the kinetic analysis applications, namely the determination of the limit of quantification (LOQ) and the limit of detection (LOD), were carried out. For analytical results, the linearity of the FEN-imprinted SPR chip based on S-g-C3N4 was determined as 1.0-10.0 ng L-1 FEN, and LOQ and LOD values were obtained as 1.0 ng L-1 and 0.30 ng L-1, respectively. Finally, the prepared SPR sensor's high selectivity, repeatability, reproducibility, and stability will ensure safe food consumption worldwide.

Strong coupling in mechanically flexible free-standing organic membranes.

Strong coupling of a confined optical field to the excitonic or vibronic transitions of a molecular material results in the formation of new hybrid states called polaritons. Such effects have been extensively studied in Fabry-Pèrot microcavity structures where an organic material is placed between two highly reflective mirrors. Recently, theoretical and experimental evidence has suggested that strong coupling can be used to modify chemical reactivity as well as molecular photophysical functionalities. However, the geometry of conventional microcavity structures limits the ability of molecules "encapsulated" in a cavity to interact with their local environment. Here, we fabricate mirrorless organic membranes that utilize the refractive index contrast between the organic active material and its surrounding medium to confine an optical field with Q-factor values up to 33. Using angle-resolved white light reflectivity measurements, we confirm that our structures operate in the strong coupling regime, with Rabi-splitting energies between 60 and 80meV in the different structures studied. The experimental results are matched by transfer matrix and coupled oscillator models that simulate the various polariton states of the free standing membranes. Our work demonstrates that mechanically flexible and easy-to-fabricate free standing membranes can support strong light-matter coupling, making such simple and versatile structures highly promising for a range of polariton applications.

First Observation of Negative Capacitance in Molecular Ferroelectric Thin Films.

On the path of persisting Moore's Law, one of the biggest obstacles is the "Boltzmann tyranny," which defines the lower limit of power consumption of individual transistors. Negative capacitance (NC) in ferroelectrics could provide a solution and has garnered significant attention in the fields of nanoelectronics, materials science, and solid-state physics. Molecular ferroelectrics, as an integral part of ferroelectrics, have developed rapidly in terms of both performance and functionality, with their inherent advantages such as easy fabrication, mechanical flexibility, low processing temperature, and structural tunability. However, studies on the NC in molecular ferroelectrics are limited. In this study, the focus is centered on the fabricated high-quality thin films of trimethylchloromethyl ammonium trichlorocadmium(II), and a pioneering investigation on their NC responses is conducted. The findings demonstrate that the NC exhibited by molecular ferroelectrics is comparable to that of conventional HfO2 -based ferroelectrics. This underscores the potential of molecular material systems for next-generation electronic devices.

A Memristive Oscillator

AbstractMemristors, or more generally “memristive systems,” are nonlinear electric components that change their resistance depending on a set of state variables. Meanwhile, negative differential resistance (NDR) is an uncommon electrical property that occurs in a few nonlinear electric components. Such a nonlinear property is now widely used in amplifiers and oscillators. It finds that one of the bilayer‐type nickel‐dithiolene complexes shows nonlinear transport with the NDR property and self‐oscillates under a bias current by simply adding a capacitor in parallel. Surprisingly, the Lissajous figure of this molecular material shows a “pinched hysteresis loop” typical of a memristor, and an inductive reactance emerges when a bias current or voltage is applied to the sample. Herein, a new type of oscillator that uses the NDR and hidden inductive properties of a memristive system is reported. The findings suggest that a memristive system can mimic other passive elements, such as an inductor, and can oscillate itself without having them in the circuit. The oscillation mechanism is straightforward and applicable to a wide variety of memristive materials, including resistors with large negative temperature coefficients, discharge tubes, and even nerve cells in the living body.

2.2]Paracyclophane‐Based Double Helices: Tunable Circularly Polarized Luminescence Driven by Self‐Assembly

AbstractAchieving high luminescence dissymmetry factors and quantum yields in the solid state remains a significant challenge in developing circularly polarized luminescence (CPL) materials. This study presents the synthesis of double helices based on planar chiral [2.2]paracyclophane ([2.2]PCP) and tetraphenylethylene (TPE), which exhibit chiroptical and aggregation‐induced emission (AIE) properties. In particular, the double helix with long alkyl chains demonstrates tunable CPL activity driven by self‐assembly, exhibiting dissymmetry factors ranging from 10−4 to 10−2. Notably, doped PMMA films show an amplified dissymmetry factor of 0.058 and a high quantum yield of up to 51%. The designed molecules represent an ideal molecular functional material for generating efficient CPL with controllable dissymmetry factor and high emission efficiency in the solid state. This opens up possibilities for applications in chiroptical sensing, data storage, and light‐emitting devices based on solid‐state materials.

Application of SFEM Method to Analyse Crack Parameters of Ultra High Molecular Weight Polyethylene Material

The application of numerical methods, today occupies a much needed place for modeling, and for finding solutions to any problem related to fatigue and damage to materials. This article deals numerically with the evolution of the stress intensity factor and the integral of the contour J in I mode, of an initial rectilinear crack of languor a=0.7, 1.4, 2.1, 2.8 and 3.5mm, with different ratio, a/w=0.1, 0.2, 0.3, 0.4 and 0.5mm. By the stretching finite element method (SFEM) of the (UHMWPE) Ultra High Molecular Weight Polyethylene material. On the other hand, the creation of the parametric mesh based on the computer language (FORTRAN) and to create a model of the square crack front with 5 contours of size L=1mm. In addition, the simulation was done by Abaqus 16.3.1 code. The maximal circumferential stress criterion MCSC were applied. Other materials like Alu20- 17 and Steel XC65-90 were used to make the comparison. Crack parameters, such as stress intensity factors KI, KII and J-contour integral were evaluated. The results obtained in our work have justified that there is proportionality between the three materials.

Superlubricating UHMWPE composites with functionalized carbon nanotubes reinforcement applicable to artificial joints

Polyelectrolyte-grafted ultra-high-molecular-weight polyethylene (UHMWPE) has been proven efficient in friction and wear reduction. However, owing to the damaged molecular structure and material stability, the modified material experiences compromised mechanical and tribological properties under immersed, aqueous working environment. To achieve enhanced material strength and water resistance, carbon nanotubes (CNTs) were modified and used as reinforcing agent. Nanoindentation tests and macroscopic reciprocating friction tests have shown significant improvements in mechanical and tribological properties: friction coefficient and wear rate down to 0.0086 and 5.6 × 10−8 mm3(Nm)-1 under saline-lubricated conditions, which maintained relatively stable during 120-day saline pre-soaking. This combination of strong hydration lubrication and superior material strength offers a promising design of superlubricating artificial cartilage with high wear resistance and long lifetime.

Distyrylbenzene-based semi-conducting molecular material for OLED applications: Synthesis, characterization and TD-DFT calculations

New semi-conducting molecular materiel (M-DSB) based on the distyrylbenzene π-conjugated system was synthesized via the Wittig reaction. The structural properties of M-DSB, displaying three different stereoisomers E-E, Z-Z and Z-E, were investigated through density functional theory (DFT) optimization. The detailed TD-DFT analysis provided insights into the structure-property relationships and revealed good agreement with experimental data. This photoactive material exhibits nearly the same UV–visible spectra in dilute solution and as solid thin film, with a maximum absorption at 363 nm and an optical gap of 2.99 eV. A broad and red-shifted photoluminescence spectrum was obtained in the solid state with blue emission compared to the solution which shows purplish blue emission with relatively narrow emission. The HOMO/LUMO energy levels were calculated by cyclic voltammetry measurements and indicate a p-type semiconductor material. The temperature and frequency dependence of the conductivity shows an activation energy value of about 0.89 eV for the M-DSB thin layer. Impedance spectroscopy of the ITO/M-DSB/Al device indicates a typical behavior of a single relaxation process and confirms that the electrical response becomes faster and the mobility of the charge carriers is enhanced by increasing the temperature.

Thermal pyrolysis properties and security performance of molecular perovskite energetic crystal (C6N2H14) (NH4) (ClO4)3 (DAP-4)

DAP-4 (C6N2H14) (NH4) (ClO4)3 has been synthesized recently as an ammonium perchlorate-based molecular perovskite energetic material with higher stability and outstanding performances. In this study, rapid thermal cracking infrared spectroscopy is applied to study the thermal pyrolysis properties and combustion process of DAP-4. Under different temperatures and pressure with a heating rate of 1000℃·s-1, the gaseous products in the rapid pyrolysis process are mainly CO, CO2, H2CO, HCN, and HCl. Above 700ºC, the pressure affects the ratio of the gas products, but the temperature does not. Based on the relative ratio of the different gas products, a thermal pyrolysis mechanism was proposed. The heat of explosion (ΔHdet), enthalpy of combustion(ΔcHθ), and standard enthalpies of formation (ΔfHθ) are determined to be -2527.39kJ·mol-1, -2492.06kJ·mol-1 and -483.96kJ·mol-1, respectively. The self-catalytic heating time is 99.5min, the temperature at the initial detection point is 280.1 ℃, and the maximum temperature rise rate is 49.1 ℃·min-1. The thermal safety experimental results showed that DAP-4 has a relatively good security performance. This study provides new insight into the mechanism of pyrolysis of DAP-4 as a potential energetic material.

Alkaline earth metal Atom-Doped Aza-Single-Strand pyridine Helix M@SP-Helix (M = Be, Mg, and Ca) as high-performance candidates for Single-Molecular redox SPDT NLO molecular switches

Redox molecular switch is undoubted to be a good choice for the requirement of terminal molecular device. By doping an alkaline earth metal atom into the aza-single-strand pyridine helical ligand to form M@SP-Helix (M = Be, Mg, and Ca), the alkaline earth metal atom not only act the role of providing two electrons but also the type of them can significantly affect the distribution region of every two electrons on SP-Helix in the in the redox process. Our results found that the electronic and vibrational static first hyperpolarizabilities as well as the frequency-dependent first hyperpolarizability exhibit high-performance single-pole double-throw (SPDT) nonlinear optics (NLO) switching effects from its oxidized state (off form) to neutral (on form) and to reduced states (on form) as obtaining four electrons by twice. Notably, the electronic first hyperpolarizability is increased approximately 1003- and 1.34 × 106-fold from 35 to 3.51 × 104 and 4.69 × 107 au for Ca@SP-Helix. Therefore, this work can provide a theoretical reference that the alkaline earth atom doping is an important method to design high-performance NLO molecular switch material.

Hydrogen Bond Reorganization‐Enabled Dielectric Pulsing Effects in Polar Polymers

AbstractPhase transition and relaxation, both essentially molecular motions, are critical mechanisms that determine the mechanical, electrical, optical, and thermal behaviors of polymer materials. For decades, hydrogen bonding has played an essential role in the modulation of molecular motions and material properties. However, in the design of stimulus‐responsive dielectric materials and the modulation of their properties, the role of hydrogen bonding has been rarely investigated, and its effect on dielectric response behavior remains elusive. Here, observations and proof that hydrogen bond reorganization is able to act as the origin of the dielectric pulsing effect in polar semicrystalline polymers by in situ testing is presented. A two‐step hydrogen bond reorganization drives molecular chain relaxation in polar semicrystalline polymers causing a strong dielectric response behavior, opening up the possibility of modulating dielectric response behavior through hydrogen bonding. Moreover, electrode polarization can synergize with interfacial and dipolar polarizations to enhance the dielectric pulsing effect. This study also provides a blow‐spinning method for preparing large‐area, flat, flexible, lightweight, and recyclable thermo‐responsive dielectric films by continuous, efficient, and low‐cost processing.

High-Speed Modulation of Polarized Thermal Radiation from an On-Chip Aligned Carbon Nanotube Film.

Spectroscopic analysis with polarized light has been widely used to investigate molecular structure and material behavior. A broadband polarized light source that can be switched on and off at a high speed is indispensable for reading faint signals, but such a source has not been developed. Here, using aligned carbon nanotube (CNT) films, we have developed broadband thermal emitters of polarized infrared radiation with switching speeds of ≲20 MHz. We found that the switching speed depends on whether the electrical current is parallel or perpendicular to the CNT alignment direction with a significantly higher speed achieved in the parallel case. Together with detailed theoretical simulations, our experimental results demonstrate that the contact thermal conductance to the substrate and the conductance to the electrodes are important factors that determine the switching speed. These emitters can lead to advanced spectroscopic analysis techniques with polarized radiation.

Preparation and combustion performance of molecular perovskite energetic material DAP-4-based composite with Titanium powder

Preparation and combustion performance of molecular perovskite energetic material DAP-4-based composite with Titanium powder

Design of Fullerene20-thieno[2,3-c]pyrrole-4,6(5H)-dione-fullerene20 for Opto-nonlinear applications: Quantum Mechanical Study

Background:
 Many organic compounds are studied because of their nonlinear optical properties, which are crucial in photonics, optical switches, modulators, optical data storage, and other devices that use light to transport information. In experimental and theoretical researches, nonlinear optical phenomena, primarily resulting from interactions between matter and strong electric fields, have received considerable attention. Materials like these have numerous applications in science, engineering, and technology.
 Materials and Methods: Fullerene 20 has been adopted as an electron donor, which was considered an NLO molecular material, while the thieno[2,3-c]pyrrole-4,6(5H)-dione has been adopted as an electron acceptor. Fullerene20-thieno[2,3-c]pyrrole-4,6(5H)-dione-fullerene20 (FTPDF), as D-A-D, has been designed for nonlinear optical applications. Fullerene20-thieno[2,3-c]pyrrole-4,6(5H)-dione-fullerene20 (FTPDF) was studied to determine its linear and nonlinear optical properties. For FTPDF, nonlinear optical properties were calculated with DFT/B3LYP using the basis set 6-31G(d,p). Various quantum calculations determine the structural and symmetry properties of Fullerene20-thieno[2،3-c]pyrrole-4،6(5H)-dione-fullerene20.
 Results: The rotation increases the electric dipole moment µtot, average linear polarizability αo and the first hyperpolarizability βtot. And the anisotropic polarizability ∆α is smaller than the average polarizability, and the present structure has few deviations from spherical symmetry. FTPDF shows µx-switch behavior. In particular, the rotation can raise the possibility for a new type of molecular βx-switch.
 Conclusion: The Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) energies estimated by DFT for the investigated molecules have been reported here. Fullerene20-thieno[2,3-c]pyrrole-4,6(5H)-dione-fullerene20 has an increased first hyperpolarizability, making it a novel material suitable for the development of optoelectronic devices.

Microdissection of the supraoptic nucleus and posterior pituitary gland from fresh unfixed tissue

The rat supraoptic nucleus (SON) contains magnocellular neurons that project long axons that terminate in the posterior pituitary gland. To perform molecular characterization of these regions, such as transcriptome and methylome profiling, it is necessary to obtain large quantities of high-quality RNA and DNA. Prior methods to isolate molecular material from these small regions required fixing or freezing and laser microdissection of whole tissue, which can compromise recovery and integrity. We have established a straight-forward method of dissecting out the SON and posterior pituitary gland from fresh, unfixed tissue that allows for the isolation of RNA or DNA without compromising nucleic acid integrity. Furthermore, this method can be used as a framework for the microdissection of any region of the brain to isolate any sensitive material. In this manuscript, we describe step-by-step instructions from the macro scale dissection, to brain sectioning, and finally the microdissection of the appropriate tissue.•Transcardial perfusion without fixative prevents the shortcomings of nucleic acid cross-linking.•A fast method and the maintenance of tissue in ice-cold HBSS during dissection and sectioning prevents nucleic acid degradation.•A vibratome is used for the sectioning of fresh brain tissue without freezing or gelatin embedding (i.e. cryostat or microtome).

Non-aqueous calcium-based dual-ion batteries with an organic electrode of high-rate performance

Calcium-based batteries are considered a promising candidate for the sustainable energy storage system of the next generation because of the abundance of Ca. However, the development of Ca-based batteries is hindered by the incompatibility between metallic Ca and common electrolytes as well as the absence of calcium-ion-hosted materials with good performance and cycling stability. Herein, we firstly investigate a small molecular organic material, 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), as the calcium-ion host for calcium-ion batteries (CIBs) in the non-aqueous electrolyte. Spectroscopic, structural, and computational studies reveal that PTCDI with an enhanced Ca2+-storage degree can increase the solubility of reduced PTCDI due to the reduced π-π interaction, suppressed by the saturated electrolyte owing to the high redeposition rate to form a PTCDI film with strengthened hydrogen bonds, which facilitates a fast enolization reaction for Ca2+ storage. A cell assembled with the PTCDI negative electrode and carbon-based positive electrode exhibits a high-power density >3000 W kg−1, a high energy density of ∼150 Wh kg−1, and superior reversible capacity of 80 mAh g−1 at 5 A g−1. The assembled CIB even demonstrates the high-rate performance (90 mAh g−1 at 1 A g−1) and ultra-stable cyclability over 4000 cycles with negligible decay at -10 °C, suggesting the promising future as low-temperature batteries.

Toward Conductive Additive Free Organic Electrode for Lithium-Ion Battery Using Supramolecular Columnar Organization.

With the aim to meet the greatest challenge facing organic batteries, namely the low conductivity of the electrodes, the electrochemical properties of a series of substituted perylene diimides able to form semi-conductive columnar material are investigated. Depending on the substituent group, a strong influence of this group on the reversibility, redox potential but especially on the gravimetric capacity of the electrodes is observed. In the case of substitution by a simple propyl group, the corresponding diimide shows a complete electrochemical activity with only 10% by mass of conductive additive and even shows a half-capacity activity without any additive and without particular electrode engineering. Extensive research has highlighted the intrinsic reactivity of the columnar material but also its perpetual rearrangement during charge/discharge cycles. This study shows that the amount of conductive additive can be significantly reduced by adapting the design of the molecular material and favoring the assembly of redox units in the form of a conductive column.

Evading the Illusions: Identification of False Peaks in Micro‐Raman Spectroscopy and Guidelines for Scientific Best Practice

AbstractMicro‐Raman spectroscopy is an important analytical tool in a large variety of science disciplines. The technique is suitable for both identification of chemical bonds and studying more detailed phenomena like molecular interactions, material strain, crystallinity, defects, and bond formations. Raman scattering has one major weakness however: it is a very low probability process. The weak signals require very sensitive detection systems, which leads to a high probability of picking up signals from origins other than the sample. This complicates the analysis of the results and increases the risk of misinterpreting data. This work provides an overview of the sources of spurious signals occurring in Raman spectra, including photoluminescence, cosmic rays, stray light, artefacts caused by spectrometer components, and signals from other compounds in or surrounding the sample. The origins of these false Raman peaks are explained and means to identify and counteract them are provided.

Evading the Illusions: Identification of False Peaks in Micro-Raman Spectroscopy and Guidelines for Scientific Best Practice.

Micro-Raman spectroscopy is an important analytical tool in a large variety of science disciplines. The technique is suitable for both identification of chemical bonds and studying more detailed phenomena like molecular interactions, material strain, crystallinity, defects, and bond formations. Raman scattering has one major weakness however: it is a very low probability process. The weak signals require very sensitive detection systems, which leads to a high probability of picking up signals from origins other than the sample. This complicates the analysis of the results and increases the risk of misinterpreting data. This work provides an overview of the sources of spurious signals occurring in Raman spectra, including photoluminescence, cosmic rays, stray light, artefacts caused by spectrometer components, and signals from other compounds in or surrounding the sample. The origins of these false Raman peaks are explained and means to identify and counteract them are provided.

Effects of graphene pull‐out on the interfacial mechanical properties of alumina/graphene nanocomposite ceramic tool materials: Molecular dynamics analysis and material preparation

AbstractThe interfacial mechanical properties of the alumina/graphene (Al2O3/GR) nanocomposite ceramic tool materials were studied by molecular dynamic simulations. The effects of pull‐out velocity of graphene, system temperature, vacancy defect, and wrinkled graphene on the interfacial mechanical properties were investigated. Results show that a large interfacial shear stress (382 MPa) exists between the Al2O3/GR interface. The maximum pull‐out force and interfacial shear stress increase with increasing graphene pull‐out velocity. The increase of temperature reduces the maximum pull‐out force and interfacial shear stress. Moreover, the load transfer capacity is reduced and the creep of the matrix occurs. These factors reduce the fracture toughness of the Al2O3/GR nanocomposites. A moderate amount of vacancy defects in graphene increases the interfacial pull‐out force and shear stress of Al2O3/GR nanocomposite ceramic tool. Compared with Al2O3/GR nanocomposite ceramic tools, the interfacial interaction energy and shear stress of pleated graphene and Al2O3 were increased by 13.87% and 41.08% respectively, with better toughening and reinforcement. The results are of significance in further understanding of the interfacial mechanical properties at the nanoscale and then beneficial to improve the mechanical properties and engineering performance of Al2O3/GR composite ceramic materials.